CROSS-REFERENCE TO RELATED APPLIC'ATION(S)
[OROl] 'This application rs being fled on May 6, 201 5. as a PCT International Patent
5 application and cIaim5 priority io U.S. Patent Application Serial No. 611989,335 filed on
May 6. 2014. thc disclosure of \vhich is incorporated hcrcin by reference it1 its entirety.
[@GO31 Work machines can be used to mow material, such as p'allets. dirt, and101
10 debri5. I;.xamples of \rtork lnachines inciude fork lifts, wheei loaders. back loaders,
excataiots, backhoes, bull dozers, telehandlers, etc. The work machines typically include
a work implenient (e.g., a fork) connected to the work machine. The work implements
attat-[~ectio tllc work rnachincs are typically powered by a 11)~draulics ystenl. ?‘lie hy~iralrlic
system cm include a l~ydraulicp ump that is pawereci by a pnme mover, such as a diesel
IS engine. The hydraulic pump can be corlnected to hydraulic actuttors by a sct of valves 10
control flow of pressurized hydraulic fluid to the hydraulic actuators. The pressurized
hydraulic fluid causes the hydraulic actuators to extend. retract, or rottate and thereby cause
the work implsmetit to move.
[11003] The work machine may furthcr include a propulsion system adapted to propel
20 the ~lriikm achine. The propulsion systeni may includc a hydraulic pump that is powercd
by the prime mover. 'The propl~lsions ystcnl nray inciudc a hydrostatic drivc.
SUMMARY
10t1041 One aspect of the present disclosure relates to a method of propeliirig a inobiie
work vehkle wit11 a hybrid propulsion mode and a hydrostatic propulsion mode. The
25 method includes: I) dztermining if a cment propulsion mode is the hybrid propulsion
mode; 2) determining if a selected propulsio~in iode is the I~ydrostaticp ropulsion mode:
3) enterins a first transition mode from the l~ybricpi ropuiulsioii mode if tl~cse lected
propulsion mode is the hydrostatic propulsion mode and the current propulsion mode is
thc hybrid propulsidn niode; and 4) sening an engine-pump displacenient Lirgct vIrLien in
the first frarisition mode. hi certain embodinienrs, the rnerhod may iricl~ded etermining if
the current propulsion mode is rhe hybrid propulsion mode, the hydrostatic propulsion
niode, or a no-propulsion modc; and cietemlining if the selceteii priiilulsion mode is the
hybrid propulsion mode, the hydroshti~:p ropulsion mode, or the no-propulsion mode.
.5 The method may fi~rt~iiei~r cludes ubstanltially inarching the engine-pump displacement
target to a system flow consuinption, when in the first transition mode, and closing an
acc~mmlator isolation vaive when an engine-pump flow output matches t.hc system flow
consumption, whcn in thz first transition mode. The nielhorl rnay fixther iric!udc closing
the accun~ulatoris olation ~jalvew hen both the engine-pun~pfl ow output matches the
10 system flow coi?su~nption and a drive-motor pressure wte of change is greater than a
predetermined value when in the first transitian mode. The method may further include
entering a second transition mode lron~th e hydrostatic propulsion mode if the selecterl
propulsion Inode is the hybrid propulsion mode and the current propulsion mode is the
hydrostatic propulsion mode.
15 [0005j Another aspect of thc present dis~.losurer elates to a n~cthodo f configuring a
propulsion mode of a mobile work vehicle from a hyb.brid propulsion mode to a hydrostatic
propulsiori mode. The method include\: I) determining if a selected propulsion niode is
the hydrostatic propulsion mode; 2) c o i ~ f i ~ r i na gdr ive motor displacement targel of a
drive motor to full displacen~enitf the selected propulsion mode is the Ilydrostatic
20 propulsion mode; 3) substantially nlatchirig an engine-pump displacement target to a
systein flow consuniption if the seiectcd propulsion rnode is the liydrostatic propulsion
n~odea; nd 4) closing an ac~.mnulatori solation valve 1~11ena n engine-puny flow output
n~abhssth e system flow ccinsuin~ptiona nd the selected propulsion mode is the 11ydrost.atic
propuisiorl mode.
25 [0006j A variety of additional aspects will be set forth in tlle description that follows
These aspects car] relate to individual reaturea aid to combinations orfeatures. It is to be
undersiood that bod1 the foregoing gcnerai description and the fulloeing detailed
description are exemplary and expianator). only and are not restrictive of the broad
concepts upon .which the cmbodirnents disclosed herein are bised.
DESCRIPTION OF TiIE DM\VTNGS
[@OW?] Non-limiting and nun-cxhausthc crnhudiinents arc described w-it11 ~cfercnccro
the foliowing fiksres, which are not necessarily itraw? to scale. wherein like reference
numerals refer to Lie parts throughout the va:ious views unless otherwise specified.
5 [0008] Figurc 1 is a schcnlatic diagram of a hydraulic system ha~iilgfe atures that are
cxanlples according tci thc p~i~sciploefs the prescnt discl~surc:
[@@09] Figure 2 is a schematic diapanm of rllc hydraulic system of Fipre 1 krther
illustrating a control system of the hyckiulic system:
[@@I@] Figure 3 is the schematic diagraril of Figure 1 further illustrating a first mode of
I0 the hydran6c systnn;
[@@II ] Figure 4 is the schematic ciiapram of Figure 1 filrthm illustrating a second
mode of the hydraulic system;
[@@2I1 Figure 5 is the schematic d i z ~ a mof Fi-are 1 furtlscr i1Jwtrati11.g a third mode
of the I~ydraulics ystcn~;
IS t00131 Figure 5 is the schematic diagzm of Figure 1 hriher illustrating a fourth mode
of the hydraulic syatern;
[@@I41 Fig~~7r cis thc sclienlatic diagram of Figure 1 hrther illustrating a fifth modc
of the hydraulic systc~n:
[@@I51 Figure 8 i s a schematic ciiagam of another hydraulic system having features
20 that are examples according to the principles of tlie pre~enct iisclos~ire;
[@@I61 Figwe 9 is a sclieniatic top plan view of a work vehicle iilcludiig the l~ydraulic
system of Figures 1 or 8 according to the pril~ciplcso f the present disclosure;
[@@I71 Figure 10 is a schematic diagram of still another hydraulic sysiem having
features that are examples according to the principles of the present disclosure;
25 [0018] Figure I 1 is a state chart of a transniiss~onm odc supcn~isoryc ontrol system
according to the prim-iples of the present di\rlosure, the state chart including a hybrid
mode. a hydrostaric mude, and two transition modes between the hybrid mode and the
hydrostatic n~ode:
[0013] Figure !1 is a s~~pelvisofrlyo w chart including a Lransmission mode process, a
drive silotor supervisoiy process, an m~inaen d pump ~upervisoryp rocess, and a valve
supeniisory process according to the principles of the Ivcsent disclosure;
[0020] Figure 13 is a t~ansmiusion~ nodcfl owchart suitable for usc in the transnv,sion
5 macie prc~cr'sso f Figure 12;
100211 Fi_mre 14 ir a drive motor superviso~yf low cl~arstu it-able for use wit11 the drive
nlotor supervisory procebs of Figu~e 12:
[0022] Figure 15 is an a~ginaen d pum~ps upervisc)ry tiovi chart suitable for use wit11
thc engine rind punif) supervibory process of Figure 12; and
10 100131 Figure 16 is a valve supen.isory flow chart suitable for use uith the valve
supeniwy process oTFigure 12.
[0024] Various embodiments will be described in detail with reference to the
drawings, vlrherein lilie reference nunierals represent lke parts and assemblies throughout
15 the several views. Reference to various embodin~entsd oes not limit the scope of the
claims attached hereto. Additionally, any examples set fonh in this specification are not
intended to be limiting and merely set forth some of the many possible embodiments for
tl~acp pended claims.
[0025] The present disloswe relates gcnerally to hydraulic ckuit architectures for
20 use in work vehiclca. A hydraulic circuit arcliitccturc, in accordance with the principles of
the present disclosure, can include a propel circuit and a work circuit. In crtrtain
enibodirnents. the propel ci~cuiat nd the work circuit can be powfled by a Panie hydraulic
pump stnlcnlre (e.g., a hydraulic pump or a hydraulic ~~u~nl>/motoInr )c.e rtain
emboctiments, the hydrsdic pump structure includes a single drive pump (e.g., only one
25 p w , only one pumping rotating graup, only one purnp'motor, etc.). Tn certain
embodiments, the propel circuit can include a hydraulic accumulator and a hydraulic
propulsion punll~:nlotor for powering propubion elements (e.g., wheels, tracks, etc.) of the
vlrork vehicle through a drivetrain. The work circuit can include various actuators for
poweririg work coniponents such as lifts, clamps, booms, buckets, blades, and/or otha
btructurea. The various asttrators iriay iriclude hyiira~~lciycl inders. hydraulic motors, etc.
In a preferred etnbodiment, the hydraulic architecture is used on a forklift SO (see Figure
9) where the propulsiun circuit powas a drivetrain 1 I 4 c ouplcd to drive wl~eels5 4 of thc
forklift in, and the work circuit includes vaivii~ga nd actuatw (e.g., I~ydrru~lcicy linders)
5 for raising arid loweririg a Sork 52 of rhe forkiiii 50, fix front-to-back tilting of the Sork 52,
and for lefi and righi shifting of the fork 52.
[8026] In certain embodiments, the hydraulic accumulator of the propulsion circuit can
he used to provide nu~nerousf u~ictionsa nd betlefits. For example, the provision of the
hydraulic accumulator allows the Ilyctraulic pmnp!motor and prime mover po~veringth e
10 propulsion circuit lo be cclnsislenily operated at peak efficiency or near peak efficiency.
Moreover, accu~nulatede nergy in the hydraulic accumulator can be used to provide power
for starting a power source ('e.g., a prime mover, a. diesel algine, or other engine) useci to
drive the hydraulic purnp:mutor. Additiondily, the hydraulic accumulator can be used to
provide propulsion fw~ctionalitye ven when the power source coupled to ihe hydraulic
15 punlphnotor is not ol?erating. Similarly, the hydraulic accu~nulatorc an be useit to provide
work circuit functionality even when the power source coupled to the hydraulic
pumpirnotor is not operating. Furthemlore, by operating the propulsion hyckaulic
purnpi~notora s a motor during braking/deceleration events, energy corresponding to the
deceleration of thc work vehicle can be back-fed and stored by the hyclraulic acculnulator
20 for barer re-use ti) enhance overall eficiericy of the work vehicle.
180271 In certain c.inbodimen$, one ( i s , a singlej hydraulic pump!motor je.g., a
hydraulic pump/motor 10'2, shown at Figure I ) is used to power both the propulsion circuit
and the working circuit. In such an embodiment, a circuit selector (i.e., a mode selector)
can be provided for selectively placing a high pressure sick of the hydraulic pun~pimotor
22 in fluid communication with either the propuision circuit or the working circuit. The
circuit selector car1 include one or more valves. Furthermore, a across-over valve can he
provided for selectively providing fluid comm~micailoab etween the propulsioni circuit and
the work circuit. By opening the cross-over valve, power from the hydraulic aci:umulator
can be used to drive one or niore actuators of the work circuit thereby allowing for
30 actuation of thc actuatoxx of the work circuit, evcn when tl~peo wer sourec is turned off.
When the cirwit selector has placed tl~peu n~p!motor in fluid coinn~unicationw ith the
propulsion circuit for propelling the work vehicle, the various components of the work
circuit can be acluaied by opening the cross-over valve. !?tdditionally, when the circuit
selector has placed the pump~motor in fluid cornn~unicationu 4tlith the work circuit, he
byctraulic accumulator can be useii to pl-itvide for propulsion and steering of the work
vehicle. It will be appreciated that a slezring colnponeni is preferably incorporated into
5 il~hey drai~licp rc>pulsionc ircuit. Wen the power source is tunled off, the hydraulic
accmi~ulatorc all be used ro power the steering colnpoi~e~p~owt,e r the propulsion elements,
and/or powcr the various colnponcnts of the work circuit. It will bc apprcciated that such
activities can be condacted individually or simultaneously. The cross-over valve can
provide a variable size orifice.
10 [00281 In certain embodiment\. the hydraulic pumpirnoior coicpled to the power source
is a11 upcn ciicuit pun1p;rnotol having a rotating group and a swash plate that IS adjustablc
to control an amouni of hydraul~cf luid displaced by thc pu~np/nlotorp er rotatlon of a
pump/motoi shah by the powel source. In cerlain enlbotlinents, the swaeh plate has an
owr-center conilgtration. When the punlp~nloioris operating as a punlp. the swash plate
15 is on a first side of ccnter and Blc powcr so1rrl.c rotates thc punip/motor shaft in a first
direction such that hydraulic fluid is pumped tlirough the pu~npimotor from a low pressure
side in fluid conlrnunicatior~ with a reservoiritark to a high pressure bide 111 tluluid
communica~ionm ith thc circuit selector. When t1:c hydraulic pumlzniotor is operated as a
motor, the swash platc may bc moved to a second sidc of center and hydraulic fluid from
20 thz hydraulic accumulator is d~rectedth rough tile pimnlp;n~otorf rom the high pressurc side
to thc low pressure side thclcby causing the pumpimotor shaft to rotare in the same
rotational direction that the puinp!moior sl-(aft rotatcs whcn driven by the power source. In
this way. hydraulic energy from the hydraulic accumulator can be used to start nioder
including use of the power source.
25 [0029j 'The lrropulsion pump:motor can also he an open circuit punup/nlotor having a
low pressure side connecled to ihe reseix~oir:tarlk and a high pressure side that corlmcts to
the hydraulic pump/motor coupled to the power source though the circuit selector. Tlle
propulsion pump:motor can include a rotating group and a \wash pfate that can be adjusted
to control displacement of the propulsion pumpimotor for each rzvolution uf a sl~afoi f the
30 propulsion pwnpmotor. The swash platc can bc an over-center swash plate that allou7s for
bi-directional rotation of the shaft of the propulsion pump/n~otor.F or cxa~nplew, hen the
swash plate is on a tirst side of center. hydraulic fluid flow through the pumpimotor from
the high pressure side to the low pressure sidc can drive tire shaft in a cloclcwise direction.
In contrast, v:hcn thc swash piatc is on a second bide of ccntcr, ilydiauiic fluid flow
tluough tire p101111Ision pumpiinotor In a dirc~,tionii olu the high 13rcssure sicic to the low
pressure side causes rotation of the sllafi ill a coi~nlerclackwise direction. In this way, the
S propulsion purnpiinotor can be used ro drive rile work vehicle in bat11 forward and
realward directions. Moreover, during a braking event. thc propulsion pun~pin~orocarn
hnction as a pump and can ctirect hydraulic fluid from thc rcsslvoir to the hydraulic
accuniulator to charge the hydixulis awurnulator thereby capturing energy associated with
the decclcration. Tl~ust,h e propulsion punll_l:motora nd the hydraulic accuniulator provide
10 a brakingdcceleration anci encrgy storage hnctiou. it will bc appreciated that in othcx
embodin~ents( e.g., an embodiment iIlustrated at Fihwre 8>,w iving can be used in
cornbination with non-over-center pun~pimotorsto provide the same or similar
ht~ctionalitya s the over-center pun~p/motorsd escribed above. The non-over-center
puinl~in~otoarnsd the valving can be nscd as ihe hydraulic pumpi3notor couple~tio the
15 power source, a? shown at Figure 8. andior can be iised as the propulsiori hydraulic
pumpinlotor k i t is coupled to the drivetrain.
[80301 Fur-ther details of such a hy&aulic circuit architecture are described and
iliustrated at U.S. Patent Publication US 2013:028011 I A1 which is hereby incorpomfed
by reference in its entirety. Figures 1-10 illust~atev arious hycil-aulic circuits and a ~:ontrol
20 system 500 arid further illustrate the hydra~ilicc ircuit architecture in a context of a work
rnachirie 50. Mcfhods of operating such a hydraulic circuit arclctecture are described and
illustrated hereinafter.
(00311 According to the pri!~cipleso f rhe present disclosure. meti~odso f opcraling the
hydrdulic circuit architechne provide sn~ootha nd beneficial use of thc work machinc 50.
25 HydrauIic hybrid veliiclc~ty pically operate at pressures below a maxin~ums ystem
operating pressure lo allow for energy storage capacity in an accutnulator and to increase
operating displacen~ento f a pump and rnoror tci increabe punlp and rnutor efficiency.
However, this tyipically limits the torque that can be dslivered quickly to a drivetrain when
climbing a hill, accelerating hard. or any other tiinz that high torque is desired. This lack
30 of instantaneous torque can bc clitniuatcd by isolating thc high pressure accunulator from
the syste~na nd operating the vchicic in a typical hydrostatic mode where lxcssure @nd
thcreby torque) can be raised veiy quickly and to pressure le\.els that rnay exceed an
operating pressure of the high presswe accumulator.
[B)Q32j Turning now lo Figure 1 I, an example txansrnissiori mode supenrisory control
srate machine 650 is jlh%trdtsted according to the principles of the pl.esmt disclosure. 4 s
5 depicted, the coirtrol state machine 651) incltides a hybrid mode 060, a hydrostatic mode
670, a first transition rnode 680, and a second tramitian mode hY(:l. The first lransirion
mode 680 is activated when irai~sitioningi iorn the hybrid mode 660 to the hydrostatic
mode 670. Likewise, the second trarrsition inode 690 is activated wi~entr ansitioning from
the hydrostatic mode 670 to the hybrid mode 660. At: depicted. a path 692 illustrates a
10 switch from the hyhrid inode 660 to the first rrar~sitionm ode 680. Likewise, a path 694
illustraies sra.itir.lling from the first lraasition inode 680 to the hydrostatic mode 670.
Eirniiarly, a path 696 illustrates s\vitching from the hydrostatic mode 670 to the second
transition mode 690. Atid, a path 698 illustrates switching fiorn the second transition
mode 690 to the l~ybridm ode 660. As depicted, the supervisory control staie n~achine6 50
15 includes transmission n~odcs6 60, 670 and hvo transitional mdcs 680, 690. In other
embodin~entsa, dditional modes, additional transition modes, an#or additional paths
between thC various modes rnay be inciuded.
100331 A state of the transmission state machine 650 is detem~inedb y the combination
of a selected transrnissiori mode 652 and a current transmission rnode 654 and their
20 respective values as detamineci by the logic outlined in the flow charts 750A and 7508 of
Figure 13. 'The hybrid mode 660 of the control state machine 650 may include functional
and operdtional characteristics of and/or may activate a hybrid propel niode 84, further
described hereinafter. When the selected transmission mode 652 is set to the hybrid
props1 mode 84, and the current transmjssion mode 554 is set to the hybrid propel mode
25 84. the state of the transmission state machine 650 is set to the hybrid propel mock 660.
The hydrostatic mode 670 likev.ise may include operational aid fuiclional characteristics
of and/or inay activate a hydrosialic mode 86, further described hereinafter. When the
selected transmissjon mode 652 is set to the hydrostatic mode 86. and the current
transmission rnode 654 is set to the hydrostidtic ~noiie8 6, the slate of the Wans~nissions tale
30 machine 650 is set to the hydrostatic propcl mode. 670.
[0034] depicted at Figure I 1. the transmission mode suparvisory control state
machine 650 (i.e., tile supervisory controller) has the two states of the hybrid inode 660
and the hydrostatic rnode 670. In other embodinlenrs, additional states nlay be included.
For exainple, a ~vorkc ircuit state that ii~cludeso perational and functional characteristics of
andor activates a work circuit primary mode 82, described hereinafter, may be included.
[0035l 'The transition modes 680,690 are defined to control transiticlnal behavior
5 between the states (iSO. 670. In particular, the first transition mode 680 controls tile
transitional behavior ~vhzrsi witching from the hybrid mode state 660 to rhe hydrostatic
rilode state 67G. Likewise, the second Wansition mode 690 controls the transitional
behavior wl~eas witciiing from the hyiirosiatic niode state 670 to the hybrid ]node state
660. In other enibottimeias. other trznsitional modes inay be defined to and froin the
10 various other stales (e.g. a state ir~cludingo perational and functional characteristics of
and/or activatii~gth e work circuit prinrary mode 82).
[(I8361 The current transmission mode 654 is defined by the existing statc of thc valves
and systenl actuators. Thc sclected transmission mode 552. is defined by operator
behavior. ?'he state of the transmission mode of the control state machine 650 detines the
15 hybrid sysfern component behavior when in the hybrid mode 660. Likewise. the slate of
the transmission rnode of the control state machine 650 defiiles the hydrostatic systernl
conlponent behavior when in the hycirostatic niode 670. When in the first wansitioi~n iode
680, the selected transmission mode 652 is the hydrostatic mode 86, and thL- cunent
transrnission inode 654 is tile hybrid propel mode 84. Likewise, when in ihe second
21) transition mode 690, the selected transniission mode 652 is set io the hybrid prq~enli ode
84, and the airrent transrnission mode 654 is set to the hyd~ostaticn lodit 86. The state
machine 650 is cxecuted on every computational loop of the supervisory algorilfim, in
certaii embodiments. In the depicted embodiment, the current lmnsmission n~odeis
deternlined first, and the selected transmission mode is deternlined second.
25 [8037j Turning now to fi-me 12, an example supervisory flow chart 700 is illustrared
according to the principles of the present disclosure. In pammkar, the supe~visoryfl ow
cIlwl700 includes a transmission mode process 750. As depicted, the transmission mode
process 750 includes a cuneni lraiis~nissionm ode process 750A and a selected
transmission mode process 750B. A path 705 illustrates nansferring from the current
30 transmission mode prcxess 750A to the selected trtansn~issionm ode process ?50B. The
supervisory I3o1.i char: 700 fkther includes a nzotor s~~pervisoprryo cess 850. A path
715 illustrates transfirring from the trxnsn~issionm ade process 750 to tbe drive rnotor
supervisory process 850. The supervisory flow chafi ?(:I0 fiirther iricludes an engine aiid
pullip supervisory process 900. A path 725 iilustratex transfering fiotn the drive nlotur
arpelvisory process 850 to the engine and puoql supervis~)ryp rocess 900. 'The
n~pemisoryf low charr 700 further includes a valve supervisory process 950. As depicted,
5 a path 7.35 illustrates iransferrii~gf iorn the engine an3 pump supervisory process 9r)O to
the valve supervisory process 450. .A path 745 also illustrates transferrii~gf iorn the valve
sul?erviso~yp rocess 9 0t ~ tl~ctr a~lsmissionm ode process 750.
[06381 Turning now to Firare 13, a11 example flow chart illustrating the transmission
mode process 750 is illustrated according to the principles of the present disclosure. The
10 iransniission rnode flow chart 750 includes a currerit trarralnissiori mode process 7SOA and
a selected frai~missionn iode process 7508. The currerit trarisrnission mode process 751iA
detern~inesth e cl~rrenot r existing state of the transmission. This deinmnination is based on
the ktlown valve and actuator states and/or the commanded valve and actuator states if
some or all of the valve position sensors are not available. The current haiismissioi~n iode
15 654 is detcnnincd by what nmde is currently being exmutcd on a work machinc 50. Thc
current transmission mode process 750A is thereby a process used to calculate the current
transniission node 654. The selected transmission mode process 750B is a process used
to select the next transmission mode state based oti operator coiitrolied parameters and the
existing sensors, valves, and actuator states of the work nrachine 50. 'The transmission
20 rnode flow chart 750 includes a pluralicy of tests and evaluations to determine ihe current
trararnission rnode 654 znd the selected transniission niode 652.
[0039] A first test set 800 of the current tian~missionm ode process 75OA includes a
test 802 to determine if the operator desires to accelerate or dezclerate. The first tcst sct
800 also incluries a tcst 80.3 to detennine if an accu~nulatori solaiio~v~al ve 210 is
25 energbed (i.e., open). The first test set 800 further includes a test 806 to detennine if a
previously selected transmission mode 6521) is the hybrid propel mode 84. Logical ~ a h ~ e s
of ~esulfso f each uf tl~ete sts 802, 804. arid 806 are ANDecl at a logical AKD 808. In
particular, the output of each test 802. 804, and 8U6, eic. are all binary and combined at the
AKD @te 808 ui11g Bo~leaillo gic.
50 [OB4Bj 'The nansmission mode flow chm 750 further i~icludesa second test set 8 19.
The second test bet 810 il~cludesa test X i l to determine if h eo perator debire5 to
accelerate the work machine 50. The secorid rest set 810 includes a test 812 lo determine
if a prirne mover ii!l (e.g.. an engine; it; ''oil" lie., running). The secondtsst set 811)
include... a lest R13 to dcteriniie ifthe accr~rnulatoris olation valve 210 is de..encrgized
(i.e., closed). 'The second test set 810 includes a tcst 814 to dciennine if a work circuit
valve 206 tie., an engins pump on valve) is de-energized (i.e., closedj. 'T'he second test
5 set 881 0 includes a test 8 15 to determine if a main isc:lation valve 208 is de-energized (i.e.,
open). The second test set 810 iiicludes a test 810 to determine ifa displaceineilt of a
drive motor 108 (e.g., a pu~np:motori has reached a n~axinlu~dnis placcn-tent. The sccond
test set 8 10 includes a test 81 7 to deterrriir~ci f thc previously selected transmission mode
652p is the hydrosfaiic mode 86. And, [he second test set 8 10 includes a test 81 8 to
1 i) deterlnil~cif a hydrostatic mode enable variable has been set to "aiabled". 1,ogical values
of results of each of the tests 81 1-81 8 are ANDed at a logical AN13 819. In pdrt~culat~h,e
output of each test 81 1-818, etc. are all binary and coinbilled ai the AND g t e 819 using
Boolean logic.
[OO11] The transmissioa mode flow chart 750 further kclucles a third set of tars 820.
15 Tl~tch ird set of tests 820 inclucics a tcst 8%1 to detaminc if thc curmit transmission mode
654 is the hyb~idp ropel mode 84. The third test set 820 includes a test 822 to determine if
a larget pressure of the pumpimotor 102 is greater tl~ana hydrostaiic entry pressure. The
target pressure refers to the desired pressure that puinp!motor 108 and punlpinlotor 102
should be operating at in order to achieve the operator commands. The hydrostatic entry
20 pressure is a calibration that the target pressure rieeds to exceed in order to prevent the
system frc1111e ntering hydrostatic mode 86 at too low of a con~inar~dT.h e hydrostatic
entry pressure sets the minimum threshold of target pressure to enter the hydroseatic node
86. 1"ne third test set 820 includes a test 82.1 to (jeternline if the pressure taxget of the
pumpimolo~ 102 is greater than a current prcssure d e n acc~miulator 11 6. The third rest
25 set 820 includes a test 824 to determine if an accelerator pedal percentage of full scale
activation is greater than a threshold percentage for rqucsti~lge ntry to the hydrostatic
mode 86. 'The third test set 820 includes a test 825 to (letennine if the hy(1rostatic mocie 86
is enabled. The tests 818 and 82.5 may be conlbined in certain embobodirnents. The third
test set 820 includes a test 826 to deicrinine ifa flow demand of a work circuit 300 is less
30 than a hycbostatic entry Cow. The hydrostatic entry flow is a calibration or preset constant
value that prevents hydrostatic mode entry if ioo rnuch work circuit flow demand is
present (,e.g., if work circuit flow demand exceeds a predetermkled value). The third test
set 820 includes a tmt 827 to determine if a current speed of thc work mac:hine 50 is less
than a inaxinlurn hydrostarit: rritry speed The third test set R2(! includes a test 1128 to
determine if vehicle hot ?;hid is nut preventing entry to the hydrostatic niode 86. kiot shift
is changing the fonvard-i~eutral-rcxierssew -itch ji.e.: the FNR switch) direction illtent to the
opposite of the current dirwtion of travel. in other words, putting the work machine 50 in
5 reverse while IraveIi~ylo rward and vice-a-versa. ~kriclt,l ie third test set 820 includes a test
829 to determine if a conditional tin~erh as expired. A conditional timer means that the
conciitionai. tcsts 822-827 must bc true for a prcdctcnnincct timc bcfo~cte st 829 will
become triic. The test 829 prescnts signal rmise from making (i.e., causing) a switch to a
new state. Logical values of results of each of the tesis 82 1-829 are logically AXDed at a
l i) logical 4.ND 83 1. In particular, the output of each test 82 1-829, etc, are all bina~ya nd
combinecl at the AND gate 83 1 using Boolean logic.
tOO421 'T'he transmissio~n~io de flow cl~art7 50 inciudes a fourth set of tests 833. 'lJ~e
fo~ulhse t of tests 833 inclutles a tint subset of tests 834 and a second subset of tests 835.
The first subset of tesis 834 includes a tesi 836 io deterniine if the cwrent trailsrnission
15 mode 654 is the hydrospatic mode 86. The first sllbsct of tests 834 inclucics a tcst 837 to
determine if the pressure target of the pun~pin~oto1r0 8 is less than the current pressure of
tlie accumiiiator 116. The tagel pressure refers io the desired pressure that punipimotor
108 and pump:n~otor 102 dlouid be operating at in order to achieve the operator
conimands. The first subset of tests 834 includes a test 838 to cietcnnine if the acceleratcrr
20 pedal percentage of hi1 scale activation is less than a thresliold hydrostatic exit
percenrage. The first subset of tesis 834 includes a test 839 to determine if the operator
desires the work n~a~hi5n0e to decrierate. 'I'he fi.~sstu bset of tests 834. iilcludes a test 840
to determine if the operator desires the work machine 50 to be in neutral. The first subset
of tests 834 includes a test 841 to determine if a slate of the prime mover 104 is "OF'.
25 And, the f i ~ sfub set of tests 834 includes a test 842. to determine if any faults are present
in the control systeni 500. I,ogical values of results of cach of the tests 536-842 are
logically OKed at a logical OK 846. h~ particular, the output of each test 836-842, etc. are
all binary and combined at the OR gate 846 using Boolea11 logic.
[0043] The second subset of tests 835 of the fo~rrtlsi zt of tests 833 includes a test 843
30 that detcmines if a conditional timer has rxpked. A conditional timer means that the
conditional tests 836-842 nlwt be true for a prcdetennhed time before test 843 will
become truz. The test 84: prevents hignal noise frorn inaking (i.e., carrsing) a switch to a
flew state.
[0044] Logical values of results of each of the logical OR 846 and the results of tlic
second subset of tests 835 are iogicaily ANlJed at a logical AND 848. h~ particular, the
5 output of each of the OK gate 446 and the test 843, etc, are all binary and combined at the
AND gate 848 using Booiean logic.
IQ0451 As ilhistratcd at Figure 13, the nansmission mode flow chart 750 nlay spirt at a
start position 752. As illilstrated at Figtire 12, the path 745 is a portion of a loop of the
supervisory flow char: 700. As ithistrated at Figure 13, the path 745 may begin at the star1
10 position 752 or may flow from a valve supcnrisory flow process 950. The path 745, in
each case, brings control to a decision point 754 that determines if the AND outpui ol the
logical AND gate 808 is true (e.g., is a Boolean ''1"). lithe logical hVD 808 is true. the
current transmission n:ode 654 is the hybrid propcl mode 84 and is regista ed as such at
block 756. If the output of tlie logical AND gate S08 is not true (e.g., i s a Boolean '"O"),
15 control advances to a decision point 758 that determines if the logical AND 819 is true. If
the logical AND 819 is true, tl~cu rlent transmission mode 654 is the hydrostatic mode S6
anci is registered as such at block 760. If the logical AND 819 is not true, the current
trilnsmission =ode 654 remalns as previow.1~ registttred (i.e.. does not change) at bio~.h
762. Thc results of either the bloch 756, thz block 760, or the block 762 are transmiited ae
20 coniro! pasbcs alang the path 705 fiom thc current tranmission mode process 750A of the
transmission mode flow chhrt 750 tn the selccteci tra~~smn~ssmioond e process 750B of the
transmission mode flaw chart 750.
[OB46] The selected transmission mode process 750B of the transmission mode flow
chart 750 receives the. infornration from the cu~renttr ansndssion mode process 75OA. The
25 results of the current transmission mode process 750A are carried along with resulis from
the selected Wansmission mode process 750H. The path 705 brings control to a decision
point 774 where the logical AND 831 is evaluated. If the logical AND 831 is true, the
selected transmission mode 652 is the hydrostatic inode 86 and is set and registered as
such at block 776. If the logical AND 83 1 k not true, co~~fraodlv ances to a decision point
30 758 where the logical AND 848 is evaluated. If the logical AND 848 is true, tlie selected
transmission mode 652 i3 the hybrid propel mode 84 and is set and registered as such at
black 780. If the logical AND 848 is not tnle, the selected transmission mode 652 remains
as the previously selected transmission mcxle 6521, ar~dis registered as such at block 782.
The results of the current trans~nissionm ode jxocess 75011 and thc selected trar~sinissiorl
mode process 75OH are transk~~etitd t he drive iuotor supervisory tlow cirart 850 along the
path 715.
5 [48047j Turning now to Figure 14. an example flow ckart illustrating the drive motor
supervisory process 850 is ilh~stratitda ccortiiiig to the pririciples of the present disclosure.
The drive motor supervisory fiow chart 850 begins at the selected transnlission mode
process ?50H, a dt he path 715 transfers ca~~trtool a decision point 860 that deternines
whether the selected 'miinsmission inode 652 is the hyilrostatiic mock 86. Tf the result is
10 "yes",c ontrol is translerred to block 870. atid a di~plac~~noeft itth e drive motor 108 (is.,
the p~mmpimotir)is set to 100%. If the selmted transmission mode 652 is not the
iqidrosfafic mode 86, control is transferred to block 880 where the displdcenmnent of the
drive motor 108 is set accorditig to a normal hybrid drive motor displacement target
calculation. The drive motor displacement target is released to an electronic control unit
15 502 at stcp 890. Control thcn passes to the enginc and pump supcn~isoryp rocess 900.
[0048] Turning now lo Figure 15, an exan~plefi ow chart illustrating the engine and
pump supe~visoxyp rocess 930 is illustrated according to thc principles of the present
Liisc:losure. The engine and pump sltpervisory flow chari 900 begins at the current
transmission inode process 750A. Cont-rol is trarisirred io a decision point 902 where the
20 current trdnsn~issionm ode 654 is queried to see if it is set to the hydrostatic mode 86. If
the result is "yes", control advances to block 912 wilere an engine state target is set to
"on". The engine state target value of "on" is stored and released to the control system at
step 932. Control then passes io blwk 914 urhere hydrostatic flow and pressure; targets of
the pumphnotor 102* in cooperation with tile prime n~ovcr 104, are calculated. Control
25 then nansfers to block 91 6 where a hydrostatic mode engine speed target is calcu~ated.
The engine speed target is stored aid released to the control system at step 936. Confrol
then passes io block 918 where a hydrostatic mode erigine pump displacement target is
calculated. The resulting engine. pump displacement target is stored and released to the
system ai step 9938. If the result of decision point 902 is "no", cor~f~ios lt rmsferred to
30 block 922 where a hybrid mode engine state target is calculated. The resulting engine
state target is stored and released to the control system at the step 932. Control is then
transferred u, block 924 where hybrid mode flow and presswe targets of the pumpimotor
102, in cooperation with the prirne mover i04, are calculated. Control is then iransfexed
to block 926 where a 1:ybrid mode engine speed target is calculated. The resulting engine
speed targct is stored and reieased to the control system at the step 936. Control is then
transferred to block 928 where a hybrid mode engine pump displacen~entta rget is
5 calculated. The resulting engine pump displacenlent target is stored atid released io tlie
control system at the step 938. Upon the engine siate targel. tlne engine speed larget, and
the engine pump displacen~cntta rget being caiculatcd, cirnnol is passed to the valve
sul~ervisol?p; rocess 950.
100491 Turning now to Figure 16, an example flow chart illustrating the valve
10 supeivisory process 950 is illustrated according to the principles of the present disclosure.
The valve supervisory flow clrart 950 begins ai tile selected transn~issionm ode process
750H. The valve supervisory- flow chart 9.50 incluiies a first set of tests 980 and a secand
set of tests 990. The first set of tests 980 include a test 981 that determines if the
acculnulator isolation vahe 210 is energized (i.e., is open). The set of tests 980 includes a
I5 test 982 that dctcrn~inesif tl:e sclcctcd transmission no tic 652 is the hydrostatic mode 86.
The set of tests 980 includes a test 983 that detemiincs if a drive motor pressure mte of
change is grealer tl~anze ro. A pressure rate of change greater than zera indicates iliat the
engine punq) is providing more flow into tlie ssysten: than the motor* valves, and other
llydraulic coniponclxts are consuining. If the valve closes allen this value is negative, the
20 system may cavitate. The set oftesk 980 includes a test 984 that determines if the engine
speed target is greater illan a nlini~nurni~ ydrostatics peed for the engine (i.e., tile prime
mover I04j. The set of tests 980 includes a test 985 that detemnines if the engine speed
status is greater than a minimum hycbostatic engine speed. And, the set of tests 980
iricludes a test 986 that determines if a hydraulic pressure at the drive motor 108 tie., lhe
25 lpulnpimolor) is greater than a current pressure at tllc hydra~~laicc ulnulator 116. Logical
values of results of each of the tcsts 981-986 arc ANLIed and stored at a logical AND 987.
111 particular, the output of each test 981-985, etc. are all binary and coinbined at the AND
gate 987 Boolean logic.
[0050] Thz second set of tebts 990 u~cludesa fxsl test 991 that determines if the
30 accumulaior isolation valve 2Ili is de-energizcd LC.. closed). TIlc sccond set of tcsts 990
includes a test 992 that determines if the currcnt pressure at the drivc motor 108 is below a
minimum hydrostatic mode entry pressure. And, the seccmd set of .tests 990 includes a test
?9? tkat deterniines if the prime mover 1114 (e.g.. the engine) is "ofr'. Logical values of
results of each of the tests 991-993 are ORed and stored at a logical OR 9 4 . I11 particular,
thc ontlx~ot f each test 991-093, rtc. are all binary and combined at the OR gate 991 using
Hoolcan logic.
5 [8)651] ljpon control entering the valve sul>en~borfylo w chart 950, a decision point
$152 evaluates wherher the logical AND 987 is true. If the logical .AND 987 is true. cotitrol
passes to block 954 where the accum~llatoirs olation valve 210 is closed (i.e., de-energize).
If the logical value of the AND 987 is not true, control passes ti? decision point 956 where
the logical OR 994 is evaluated. Jf the logical value of tlie OR 994 is "true", control
10 passes to block 958 where the accumulaior isolatiorl valve 211) is opened (i.e., energized).
if the logical value of the OR 994 is not true, co~iiroils transferred to block 960 where a
cuxent shtc of the accun~ulatoris olation valve 210 is ~nai.ntained.U pon the valve
supervisory flow cfiaxt 950 beire completed, control is yassed along path 745 to the
transtnission mode process 750.
IS [0052] According to the principles of ihe present disclosure and as illustrated at
~igures1:-7a, hydraulic system 100 (i.e., a I~ydraulicc ircuit architecture) is adapted to
power the drivetrain 114 of the work macrhhe 50 (i.e., a work vehicle, a mobile work
vehicle, a forklift, a lift truck, a fork truck, a wheel loader, a digger, an excavator, a
backhoe loader, dc.). The hydraulic system 100 may be furlher adapted to power a vvo~k
20 circuit 300 of the work nlachine 50. Th.e hydraulic systein 100 rnay be adapted to power a
steering control unit 600 (e.g., a hydraulic steering circuitj of thc work machine 50. 4s
depicted at Figure 9, the work machine 50 uicludes a work attachment 52 (e.g., the fork, a
work cotnpolient, eic.j, at least one drive 54, and at Ieast one steer wheel 56. In
certain cnlbodirnenis, one or more drive wheel 54 may be conibined with one or more
25 steer \wheel 56. In certain embodin~entst,h e work machine 50 may include only a single
drive hydraulic pump.
100531 The hyctraulic systern I00 is adapted to recover energy and store the energy in
a hydraulic accumulator 116 for rcuse. For example, wlicn the work macI~nc5 0 is
decelerated, the drivetctain 114 inay deliver kiiictic encrky to thc hydraulic system I00 and
30 thereby store the energy in the I~yciraulica ccumulator 116. The hyckaulic system 100 is
also adapted to quickly starl a prinie mover 104 (e.g., the internal cornbuslion engine) of
the work nnlachine 50 with the energy stored in tile l~ydraulica ecunlulalor 116. The
t~yclraulics ysienj 100 may be adapted to power the drivetrain 114, the work circuit 300,
and/or the steering conrrol unit 6iiO without the jlrinle mover 104 mnning by drawing
hydraulic powel. from the liyd~.autica ccumulator 116, lo certain enlbodiments. thc prinle
mover 104 may drive only a single l1yc1wulic pimlp. III certain emboclin~ents, tbe I. ,rnne '
5 mover 104 may drive only a singlz hydraulic pun~yt,h at powers the cirivetrain 114 and the
work circuit 300. In certain embodiments, the prirne nlover 104 niay drive oniy a single
Ilydmulic pump that powers at least the ilrjvetrain I 14 and the work circuit 300. 117 certain
en~bodirnents. tkic prime mover 104 inay drive only a single hydraulic pump erst powers
the drivetrain 1 14, the work circuit 300. and the steering control unit 600. In ceriain
10 embodin~entst,h e prime nlover 104 may drive oniy a single hyrlraalic pump that at least
po\vers the drivetrain 1 14, the work circuit 300, and the steering control unit 600.
[OOS4] 'The I~ydraulics ystem li)O operates in various modes depending on demands
placed on the work machine 50 (e.g., by an operator). A control systern 5ii0 monitors an
operator interface 506 of the work nmhine 50 and also monitors various sensors 5 10 and
15 opcraring pdramctcxs of the hyciraulic system 100. As illustrated at Figurc 2, signal lines
508 may facilitate communication within the control system 500. The ctrnnol system 5(10
i-valuates input received fiom the operator interface 506. In certain en~bodimentsa. n
electronic coIltrol unit 502 monitors the. various sensors 5 10 and operating parameters of
the hyciranlic systern 100 to configure the hydraulic system 100 into the most appropi.iate
20 mode. The modes include a work circuit prinrary mode 82, as illuslraled ai Figure 3; the
hybrid propel mode 84, as illustrated at Figures 4 and 5, and a hydrostatic mode 86. as
illustrated at Figxes 6 and 7. The electronic control unit 502 may ~nonjtorth e operator
interface 506, the prime mover 104, and en\.ironmental conditions (e.g. ambient
temperatuse). Memory 504 (e.g., RAM memory) tnay be used within the electronic
25 control unit 502 to store execuizble code, the operating parameters. the input fiom the
operator interface, etc.
[OU55] In the work circuit primary mode 82 (see Figure 3). power from he primc
mover 104 is directly supplied to the work circuit 300 by the hydraulic system 100, and
power from the hydraulic accumulator 116 is delibered to the drivetrain 114 by the
30 hydraulic systcm 100. In certain embodiments, power for the stcering control unit 600 is
also take11 from the hydraulic accumulator 116 in the work circuit primaly mode 82. The
work circuit prin~aym ode 82 may be selected when power de~wandsb y the drivetrain 1 14
are low, relatively low, anclior are anticipated to be low, and power demands and/or
hydraulic flow demaiids by the v.rork circilit 300 are high. relatively high, andlor are
anticipated to be high. Such conditions may occur, fay example. when thc work machine
50 is mwing slowly or is stationary and thc work atiaehment 52 is being used extensively
5 arid/or w-iih high loadinig. I11 $he work circuit primary mode 82, the steering conirol unit
600 may receive power frmn the hydraulic accun~ulsior 11 6.
[@US61 Tlie hybrid propel made 83 (scc Figures 4 and 5) may bc med when the powcr
delnand from thc driveWdin 114 1s donsir~atco ver the power dernand of the work circuit
300. The hybrid propel mode 84 nlay also be used when it is desired to recapture energ
10 from the deceieration of the work. niashlne 50 The hybrid propel rnode 84 may filrflier bc
used lo power the \wrh niachlne 50 bsithout the prime niovel 104 rumng or running full
time. 1-or cxample, the hybrid propel modc 84 allows thc pnme mover 104 to be shut
down upon sumciznt pressure existing in the hydraulic accilmulator 1 16. Uport depletion
of rhe hydiaulic accumulator I16 to a Iobser pressme, the hybrid prope! modc 84
15 hydraul~callyrc atails the prime niovcr 104 thereby recharging the l1~7draulica cc~insulator
116 and also providing power to the work machine 50 from the prime n~over 104. In the
hybrid propel mode 84. the breering co~ihoul nit 600 niay receike power fiom the
11ydraulic accu~niliator 1 16 and/or the prime inover 104.
[OM71 The hydrostatic rnodc 86 (see Figures 6 and 7) may be used \.ihen the demands
20 of the drivetrain 114 arc high, relatively high, and/or arc anticipated to be high. For
example, when the work machine 50 is drivcn at a high speed, when the work ~nachine5 0
is driven up an incline, and/or when thz drivetrain 114 is under a high load. The
hydrostatic mode 86 niay be used when the demands ofthe drivetrain 1 14 are sufficic~~ily
high to require a pressure within thc Ilydrdulic accumuiatox 116 to be in excess of a
25 pressure rating and/or a working pre.ssure of the hydraulic aecunlulafor i 16. The pressure
rating m ~ othre working pressure of ilie hy(lrai11ic accumuIator 116 can cor~espondirigly
be loivered in a hydraulic system that can switch between a anode (e.g., the hydrostatic
mode 86) where the hydraulic accumulator I 16 is isolated and a mode (e.g., the hybrid
propel mode 84) where the hyctraulic accumulator 116 is cormected. In the hydrostatic
30 inode 86, [he steering control unit 600 rnay reccive power from the prime mover 104.
[0058] The ctjnirol systein SO!) may ri~pidiys witcli botween the work circuit primary
mode 82, the hybrid propel niode E4, and/or the hydrosiatic mode 86 to cotltitluously
adjust thc hydraulic systeni 108 to the demands of tlic work lilachinc 50.
100591 'T'uri~ingn ow to Figure I , the hydraulic systern 100 is illustrated as a schenlatic
5 diagram. The hydraulic system 100 is powered by the prime mover 104 which is
comiened to a pumpi~notor1 02. I11 certain embodiments. the ~>umplmotoIr0 2 rnay be
replaced with a pump. As depicted. the liydraulic systenl 100 allows the liydrauiic
punlpimotor 102 to be a single pump/motor (or a single pump) tl~apt owers the drivetrain
114, the work circ.uit 300, and/or the steering control imit 6OO. By configuring the
10 hydraulic systern 100 with tlie single pnmpiniotor (or the si~igtep ump); a cost of the
hydraulic system 100 niay be reduced, a weight of the l~ydraulics ystem 100 may be
reduced, the efficiency of the hyd~auiics ystein 100 may be increased by reducing the
parasitic losses of ariditior~acl omponents, andor a packaging size of the hydraulic systern
100 rnay be reduced.
IS [0050] As depicted, the hycfraulic pilmpimotor 102 arid the prune mover 104 may be
assembled inlo an engine pump assembly 106. In ccrtain embodiments, the prime mover
104 turns in a singlc rotatio~~dailr ection (c.g., a clockwise cilrection), atid thus, the
hy&aulm pumpintotor 1112 may rotate in the sil~glero tat~onadl irection oft he prime
mover 104. Power may bc trarbferrcd between thc hydraulic purlipinlotor 102 and the
21) prime nlover 104 by a shaft (e.g., an input!output shaft of the hyciraul~cp un~p/motor1 02
may be conne~%etdo. a cr~nkshafot f thc prime mover 104). The polver is typically
transferred from the prirne move1 104 to the hydrauilic pumplmotor 102 when the
hydraulic pump/motor 102 is s~ipplyingh ydraulic power ro the hydraulic ac~uinulator1 16.
the drivewain 1 14. the work circuit 300. anit'or the stce~ingco ntrol unit 600. The power
25 may be wailsf~esflr om the hydraulic pump:motor 102 to the prime inovm 104 whm the
liydraulic pumpimotor 102 is starting the prime mover 104, during engine braking, ets.
[0051] The hydraulic pumpimotor 102 may be a variable displacement punip(motor.
The hydraulic pumplmotor 102 may bc an over-center pimnipirnotur. The hydraulic
pumph~~oto10r 2 includes a11 inlet 1021 (i.e., a low prcssure side) that rcceives hyckaulie
30 fluid from a tank 1 18 via a low pressure line 440, and the hydraulic pumpimotor 102
includes an outlet 10211 (i.e., a high pressurz side) that is connecleri to a high plessure line
400 of [he hydraulic puinplmotor 107. When the prirne mover 104 supplies power to the
iiydrauiic p~unpimotor1 02, l~yd~auifilcu id is drawn froin the lank 118 into the inlet 1021
of [hi. hydraulic puinp'motor 102 and expelled from !he outlet 10211 of the hydi.aulic
punlp'~notor 102 at a 11ighcr pressuse. h.1 certain embodiments, power may bc delivered
from the hydraulic pump;inotor i 02 to the prime mover 104 when a swash plate of the
5 hydra~dicp ump/motor 102 is positioned over cenier and high pressure hydraulic fluid
froin the high pressure line 400 is driven Dackvvards tluough the hydraulic puinp:n~oror
102 and ejected to the 1i.w pressure line 440 axid to the rank 11 8. Alternatively, as
ili~istrateda t Figure 8, a reversing valve 103 of a hydrxulic system 100' can be med to
cause the prin~em over 104 to be backdriven w-it11 a I~ydraulicp umpiinotor 102'- similar lo
10 thc I~ydraulicp urnl~ln~oto1r0 2.
[0062j .4 flow control device 202 (e.g., a rcl~efv alve) includes a connection to tl~c
high pressure line 400. Upon llydraulic fluid pressure wlthln the high pressure line 400
reaching a predetermined linut, thz flow cori~odle vice 202 opens and dumpa a portion of
the hydraulic f l ~ ~tiod th e tank 118 and tlnereby protecting the high pressure tine 300 from
15 reaching an over prcssure condition
100631 A flow co~itrodl evice 206 is coi~nectedb ctvieen thc high pressure linc 400 and
a high pressure line 406 of tlie work ci~cui3t 00. In the depicted embodiment. the flow
control device 206 is a work circuit valve.
100641 A flow control device 208 is connected between the high prcssure line 400 and
20 a high pressure line 402. As depicted, the high presame line 402 rnay be connected to an
inlet 108h (i.e., a high pressure sidc) of a pump/motor 108. Thc flow cont~odl evice 20s
may be an isolation valvc. In ccriajn enibodilnents, the flow control device 206 and tl~c
flobv control device 208 may be combined into a single three-way valve 207 (see Fi~are
8)
25 [0065] The high pressure line 4 02 is conu~ectzd lo the hydladic accumulator 1 1 6 by a
thid flow control device 210. In the depicted embodiinent, the fluid flow control debice
2 10 is an isolation valve for the hydrauljc accumulator 116 . In tl~ede picted embodirnent,
the fluid flow control device 210 and the hy&aulic accumulator 11 6 are connected by an
accun~ulattvli nz 404.
30 [0066] Thz high pressure line 402 is f d i e r connected io he high pressure line 406 by
a $low control device 212 and another flow control devicc 224. In the depicted
enlbodirnent, the flow control device 212 is a Valvistor3I proportional ilo\v control device,
and the now coni:ol ilevicc 224 is a check valve that prevents hydmulic fluid from the
high pressure lirle 406 fr~?xne ntering the high prcssure line 402. in the depictcd
embodiment, the fl(jw conlrol devices 212 and 224 are connected in series along a cross-
5 over now line 408 that connects lhe high pressure line 402 anci the high prehiure line 406.
111 other embodiments, a single flow control device may be used along the cross-ova flow
line 408,
[00671 Certain aspects of the propijlsion systen~o f the TVOmI.a~c hine SL1 will now be
ctescribed. 'The propulsion system inch~desth e pu~np!motor 108 that both transmits and
10 receives power. lo arrd froni the drivetrain 114 via an output shaft 110. In paeicular, the
output shaft 1 10 is connecteif to P gear box 112. As illustrated at Figure 9, the gear boa
112 may include a difkrenfial counmted to a pail. of the drive whecls 54. In otlser
emboilirnerits. a hydraulic pumpirnotor may he iricluded at each of the drive wheels 54,
and the differential may not be used. \\'hen sending power to the drivetrain 114. the
15 punrp:motor 108 nray acceieratc the work machine 50, rnay move the work machine 50 up
an incline, and/or may othem~isep rovide overall movement to the work machine 50.
W1ieii the work rnachirie 50 decelerates andor travels down an incline, the puxnpi~nolor
108 niay receive energy froin the drivetrain 114. When the hydraulic system 1i)O is in the
hybrid propel mode 84 or the work drcuit primary mode 82, the pump!mi!tor 108 may
20 send hydraulic energv to the hydraulic accumulaior I 16. In particular, the pump:'motor
I08 rnay rczeive hydraulic fluid froin the talk 118 via the low pressure line 440 and
pmsurize the hyclraulic fluid and send it tJirough the high pressure line 402 through the
fluid flow control device 210 and the accumulator line 404 and into the hyctraulic
accurnulalor 1 16.
25 [0068] The pumpinlotor 108 may be clriven by hydraulic power froni the hyclraulic
accunl~~laio1r 1 6 or the hydraulic pump!motor 102. In particular. when the hydraulic
bystein 100 is in the work cireuit primary niode 82, the pumnp/motor 10s receivcs the
hyctraulic power from the hydraulic accumulator 116, .ds illustrated at Figme 3. When the
hyctraulic system 100 is in the hybrid propel mode 84. a\ illustrated at Figures 4 arid 5. the
30 pumpimotor 108 may rcceivc hydraulic power from either thc hydraulic pu~np/inotor 102.
tbe hydrauiic accumulator 1 16, or both the l~ydraulicp onqwnotor 102 and tlte hydrai~lic
accumulator 116. \%en the hydraulic system 100 is in the hydrostatic mode 86. as
illustrated at Figures 6 and 7, [hi. purnphnolo: 108 receives power from the liydrmlic
pumpi~-notor 102. Iio\vri,er, the purnpiinotor 108 may deliver power to the l~ydraulic
punlphaotor 102 and the prirne ~uover 104 may thcreby provide engine braking.
LO0691 A relief valve i'. 14 may be connecied hetwecn the hi& pressure line 402 and
5 the tank 118. Feedback from the high pressure line 4(!2 mag be given to the hydraulic
punlp;niotor 102 by way of a p~nnp/niotorc ontrol pressure valve 220 (e.g. a pressure
reducing valve). In particular, a poult of use filter device 222 is connected between the
high pressme liile 402 and the pun~pimotor control Ixcssurc valve 220. The punlphnotor
controI pressure valve 220 may feed a pressure signal to the hydraulic pun~plniotor 102
10 and thereby control ilie t~ydra~ilpicu mpin~oior1 02 in oerlain embodiments andlor in
certain 111odi.s.
[08)70] In thc depictcd embodiment, the stscring control unit 600 ruteivcs hydiaulic
powa from the h~ghp ressure line 402. In particular, an intemediatc pressme steering lme
420 is connected to the high pressure ln~e40 2 *ia a steering feed valve 218 (e.g., a flow
I5 corltroi vake) and a steeling feed valve 216 (e.g., a pressure reducing valve). A return
linc 422 is corinectcd bctwcen the steering control unit 600 and the tank 118.
[Q571] Various components may be uicluded in a manifold block 200. Fur exaniple,
the flow control device 202, the flow conrrol dcvice 206, &c flow control dcvice 208, the
fluid flow control device 210, the flow control device 21 2, the relief valve 2 14, the
20 pumpimc>tor control pressure valve 230. the device 222. andior the flow control device 224
may be included in the manifold block 200.
[0572] Turning now to Figure 2, a schematic diagram of the control system 500 is
chown w~tha schematic diagtam of the hydraulic sysirm 100. As can be scnl, the
hydraulic system 100 monitors a plurality of sensors indicating the state of the hydraulic
25 system 100. Tr~eco ntrol systern 500 further maniton the operator ititerI-ace 506 the~eby
allowing an operator ro t&e control of the hydraulic system 100 and thereby take control
of the work machine 50. 'Tl~e electronic control unit 502 of the controi systenl5GO may
perform calculations that model the hydmulic sybtein 100 in the various moder and
thereby d2tennine the optimal mode and thereby select thc optimal mode for the given
311 working conditions and the given operator input. Under certain conditions, tl~cm ode of
the hydrdulic system I00 is selected to maximize fuel zsciency of the work machine 50.
In other conditions, the nlocie of the hydraulic sysrenl 100 is selected to nlaxirnize
perforxilance of the hydraulic system 100 and thereby the work machinic 50. The
electronic control unit 502 may learn a working cycle that the work macl~ine5 0 repeatedly
~mderttakes. By learning the kvclrking cycle. the electronic conlrol unit 502 can maximize
S efficiency for the wclrking cycle and identify when the work machine 50 is in the working
cyck. Tlie eiccl~onicc ontrol unit 502 tnap scvitcli modes differently depending on wllich
working cyclc the work ma~:line 50 is in. By switching modes throughout the working
cycle, various parameters of the hydraulic system 100 can be optiniized for efficiency or
perfomlance. For example, charge pressure of the l~>rdrauliacc cumulator 116, swash plate
10 angle of the l~ydraulicp u~np~n~o1t0o%ra nct!or the l?u1np?'motor1 08, andlor tl~cti ming of
starting and stopping the prime mover 104 may be detern~inedb ased on the working cycle
of tlie work machine 50. The control system 500 may emulate a conventional work
machine such that the work machine 59 behaves and feels like the conventional work
machine to the oilerator.
15 [OW31 Turning now to Figure 3. thc work circuit primary mode 82 is ilhstrated. The
work circuit primary mode 82 is selected by the control system 590 wlten the work
attach~nznt5 2 is under heaty use, sustained use. and/or use that rzquires high volumelric
flow ratcs of hydraulic fluid. The drivetrain 113 of the work machine 50 is operational in
the work circuit prirna~yn ~ode8 2. In particular, the hydraulic accuniulator 1 I h can supply
20 powei to and receive pourer from il~ep~ inipimotor1 08. LTp.~pont lie hydraulic accumulats~
I16 being depleied to a given lcvel. the control system 500 may quickly switch the
hyclraujlic system 100 into the hybrid propel mo~fe8 4 to recharge thc hydraulic
accumulator 1 16. Upon the hyctraulic accumtllator 1 1o be~ngre charged to a given
pressure level, the control system 500 may return the hyhulic system 100 to the work
25 circuit primary mode 82.
I00741 Tunling now to Figure 4, the hybrid propel mode 84 is illustrated. I11
palticular, a hybiid mode 84a is illustrated. The hybrid mode 84a alli)vtvttsh e exchange of
energy between the hydraulic pumpimotor 102. the hydraulic accumulator 116, and the
p ~ ~ ~ ~ p h n1o08i.o Irn p,&cular, the hydraulic pumpimoior 102 may supply hydraulic
30 power to the hydraulic accumulator 116 for rhe purpose of rcchargir~gt he hydraulic
acc~~mulato1 1r 6. Thc hydraulic pun~p:nlotor I02 may separately or sintultaneously
supply power to the pumpinlotor I08 to propel the work machine 50. The hydraulic
accunibtlator i 16 may supply power to the hy~8niulicp unip/niotor. 102 for the purpose of
starting the prime mover 104. Separately or sirnultai~eouslyth~e hydraulic accuriiulator
11 6 niay supply power to the puinpi~uotor 108 to pl.opel the woik machine 50. 'Uic
pump:'molu~ 108 may alpply hydraulic fluid power to the hyciraalic acc;cuinulator i 15 and
5 thereby charge the hydraulic accrrmulaior 116. Seperarely (,I. sim~iftaneousljl, the
pumpitnotor 108 inay provide power to the hydraulic pump;rnotor 102. The power supply
to ihc hydraulic pump/mator 102 can be used to start thc priine mover 104 andior to
provide engine blaking (e.g., upoir the hydraulic accuinutator i 16 being full). \'hen the
hydraulic system 100 is in the hybrid mode b4a, the work circ~tit3 00 may be cut off' from
10 hydraulic fluid power. In this case, the work circuit 3O0 niay havc no tienland for
hyciraulic: power.
100751 'Turning now to Figure 5, the hybrid pr~y~nelol de 84 ic again ilhatrated. hl
palricuiar, a hybrid triode 84b is illustrated. The hybrid mode 84b is similar ti, the hybrid
mode 84a except that the cross-over flow line 408 is open allowlrng hydraulic fluid power
15 from the high pressure line 402 to be siilppl~hedt o the work chcuit -300. In the hybrid mode
84b, the hydrauiic pump/motor 102, the hydraulic at.cun~uiator 116, and/or thc
pl;mpiinoior 108 may supply hydraulic power ta the vv,ork circuii 300.
[OR761 The hybrid piupel mods 84 may be preferred when the work machine 50 is
uniiergoing a moderate workload, and/or when high efficiency and/or energ recovery
20 from the dri~etrain1 14 is dcsirrd.
[0077] Turning irow to Figure 6, rhe hydrostatic niode 86 is illustrated. In particular a
I~ydroktaticm ode 86a is illustrated. The hydrostatic modr 86a may be used when the
drivetrain 114 of the work machine 50 is under heavy load For exanlple, when the work
rnachine 50 is driver] at high torqu~~pow;eanrd /or when thc -ork machinr 50 is dnven up
25 an incline. When tile hydraulic system I00 is operated in tlic hydrostatic mode 86a,
hyclraulic pressure within the high pressure line 400 and the high pressure line 402 may
exceed a working preswre m&or a rated pressure of the hydlautic accumuIator i 16. By
switching between the hybrid propel mode 84 and the hyitrosratic niodc 86, Ihe hydra~~iic
system 100 may undertake tasks that result in high prescures in thc high pressure line 491
30 without exposing the hydraulic awumulator 1 16 to the high pressures. Thus, the benefits
of the hybrid propel mode 84 can be enjayed u4thout requiring that the accumulator 116
havc a pressure mtiilg that matches the rnawimunl pressuie rating of the hydraulic
pi'n~p'niotor 102. By bypassing (e.g., isoliiting'i the accurnulaior 1 I6 with the illlid flow
contrcl device 210, the hydraulic sysiein 10!i does not need to wait [or the accuinulator
11 6 tci be pressurized up to the desired working pressure. When the hydraulic system 100
is in the hydrostatic mode 86a, thc work circuit ili0 may be cut off from i~ydraulicf luid
5 power. In this case. the work circ~ii3t 00 may have no demand for hydraulic power.
[0078] Turning now to Figure 7, the hydrostatic mode 86 is further illustrated. In
parricular, a hydrostatic mode 86b is illust~ated.T he l~ydrostaticm ode 86b is similar to
thc hydrostatic node Mba, cxcept that the cress-over flow line 408 is open allowing
hydixulic fluid power from the high pressure line 402 to be supplied to the work circuit
10 300. In the liydwstatic mode 86b, the hydraulic pumpinlotor 102 attdhr the pump;n~otor
I08 nyay supply hydraulic power to the work circuit 300.
[0079] Turning now to Figure 8, a system forming a second embodimei~ot f the
principles of the present disclosure is presented. The system incluctes tile hydraulic system
100', mentioned abilve. As many of the concepts and features are sirnilar to the first
1.5 embodiment, shown at Figures 1-7, the description for the first embodiment is hereby
incorporaied by reference for the second embodiment. Where like or sin~ila; features or
elements are shown, the. same reference numbers wili be used where possible. 'Tbe
following description for the second ernbodiment will be limited primarily to the
differences beixveeri Ihe firs! rwld secol:d en~bodiments. In the hydraulic systeni IOO', the
20 flow sol~trc~del.v ice 205 and the flow control device 208 of the l~ydraulics ysten~1 00 have
becn replaced by the single three-way valve 207. In addition, the flow control cievice 212
arid the flow coritrol device 224 of the liydraulic system 100 has been repbaced by an onoff
electrically controlled valve 2 12' and a constant flow valve 224'. The substitution of
the on-off electrically controlled valve 21 2' and the constant flow valve 224' can be further
25 made in other enlbodimaits of d ~pere sent diselostne. Likewise, the flow control device
212 and the flow control device 224 can be substituted in the present embodirnent.
[0080] Turning now to Figure 9, a schematic layout ofthe work rnachine 50 is
illustrated. In tl~dce picted embociimant, the work machine 50 is a fork truck.
[0581] Tuniing now to Figure 10, a sqstern forming a third embodirnent of the
30 principles of the present disclosure is schenlaiically illustrated. The system includcs a
hydraulic system 100". As with the hydraulic system 100, the hydraulic syatzm 100''
similarly power?; the work circuii 300. However, in the hydraulic system 100" a hydraulic
punlp 107 is used to provide hydraulic power to the ivolk circuit 300. The hydraulic pump
107, in turn, is connected by a shaft 109 to a pumpilnoror 102". A clutch 105 is opcrably
connected between the prime rnaver 104 and the hyl)id~aulipc uinp!ntotor 102". A low
5 pressure accitniulatilr ! 17 (is., a storage accumularor) is Curther included cunnecied to a
low pressure side of the hydraulic pump!n~otor 102".
[0082] By piacmg thc hydraulic pumplinolor 102" at a zero surash plate displacement
angle, power <-anf low from thc pnmc mover 1\14 thro~lght he clutch 105 and illto thc
hydraulic pump 107 Thus, pourer from die prime mover 104 can directly power the work
10 circuit 300. While the pllnle mover I04 is directly powering the \v./orli circuit 300, the
hydraulic accuri~ulaior 116 call be both supplying and receiving powcr from the
purn11,'motor I08 'rl~us,t he hydrat~lsi~ys tem 100" Iras a ~nodcsi nmifar to t11c work circuit
primary mode 82, illustrated at Fig~nc3
[00831 Hydraulic power from the hydraulic accuntuldtor 116 can be used to start the
15 prime tnover 104. In particular, hydraulic power flows from the hydraulic accmuiatar
116. through fluid flow control dcvicc 2 10, atid into the hydraulic pumpinlotor 102". Thc
c l u t ~Il 0~5 <,an be engaged and thereby thc i~ydraulicp mn~p:motor 102" can stan the priine
mover 104.
100841 Thc hydraulic pun~p/motor 102", the hydraulic accumulator 1 16, the
20 pumpirnolor 108. arid the prime mowr 104 can operate in a hybrid propel mode similar to
the hybrid propel mode 84 \%en hydraulic power is requiied by the work circuit 300, the
Ilydraulic p u ~ n10 7 can rweivc power from tlie hyriraulic punlp!motor 102" via the shaft
109. 'Thus, thr: hydraul~cs ystem IOU" has a mode similar to tlie hybrid mode 84b,
illustrated at Figure 5.
25 [0085] The hydraulic accu~nulator1 16 can b~1is olated from the punip!motor 108 by
clositig the fluid flow control device 210. In this way, the hydraulic system 100" can
operate in a hydrostatic mode similar to the hydrostatic n~ode8 6. If the work circuit 300
requires hymauiic power, the hydraulic pump 107 may receive power front the Ilydrdulic
pun~p/~tioto1r0 2" tia the shaft 109.
[0086] thccordir~g io ihe principles of the present disclosure, an example algorithni
may be incorporated in the col~trool i'the hydral~lics ystcin 100. The exampIe algoritl~rii
includes nine major conlponenis.
[00871 r he first major somponcnr t:f tl~ccx aiall4e aigoritbni is ~cic~tinthge hydrostatic
5 mode (e.p., the hydrostatic mode S6j w~thth e transmission mode su~ervisurw hen the
rollowing coridiiions, are met.
LO0881 Current mode is hybrid mode AND
(00891 Pressure targei is greater than a specific calibration AND
[BJ09O] Pressure targel is grealer than the high presswe accwn~ulator
pressure AND
100911 Accelerator pe&ai coirmiand (e.g., percentage) is greater than a
calibrated value je.g., SOU!] AND
10092j Hydrostatic mode is enabled ANTI
LO0931 Work circuit tlow demand is zero AND
(610941 Vehicle speed is less than a specific calibraiio11 (e.g., 7 hPH) hVD
[0095] Vehicle is hot siliftedat low specific calibrated speed OR vehicle is
not hot shifted
[O09A] The sccond major componcrit of the example algorithm includes: a)
nsun~ptioinf the seiected propulsion mode is the Ilyctrastatic propulsion mode; and
closing an a&cuniulator isolation valve whai arl engine-ptunp flow output matches
the systcnl flow c~onsun~ptioalrlid Ihe selected propulsion mode is tl~eh ydrostatic
propulsion mode.
17. The nlctl~odo f clainl 16, further conlprisi~igc onfiguring a drive motor
displacement target of a drive motor to a pre-detznnined displacenlent if the selected
propulsion mode is the hydrosratic propulsion mode.
18. The method of claim 17, wherein the pre-determined diqlacemerlt is fdl
displaccrnel~t.
19. The method of claim 16, wherein the hybrid propulsion mode includes pressure
based control and the hydrostatic propulsion mode includes displaceinzilt based control.
20. The method of clairn 14, further comprising calculating the system flow
consumption and thereby mai~~tainirfllgo w continuity when closing the aaunmlator
isolation valve.
21. Thit nlethod of claim 20, urherein the calculating of the system flow consu~nprion
incltrdes calculating a flow coraumption of a work circuit.
22 The mcthod uf clam 20, \+here111t he calculatlr~go fihe sybiein flu\+ col~slunption
1nc.1odss calculatillg a flow consunlptlon of a stce~~ncigic uit
23 Thc method of claim 16, u7hercii1 derrmiilrng if the selected propubion mode is
thc I~ydrostaticp ropulsion modc includes c~,aluaringi f an accclcratioll request of a11
operator requires a propuision pressure target that is greater than an acc~lmulatopr wssure
24. The method of claim 16, wherein deterniining if the selected propulsion Inode is
the hydroststir prop~rision mode irkclitdes ifetermining if the hydrostatic propulsion mode
is enabled.