Specification
The present invention relates to a method for controlling a drive
system of a vehicle, in particularly a hybrid vehicle. The drive
system comprises a combustion engine with an output shaft, a
gearbox with an input shaft, an electrical machine that compris¬
es a stator and a rotor, and a planetary gear that comprises a
sun gear, a ring gear and a planet wheel carrier.
The output shaft of the combustion engine is connected with a
first of said components of the planetary gear so that they rotate
as a unit with a first speed of rotation. The input shaft of the
gearbox is connected with a second of said components of the
planetary gear so that they rotate as a unit with a second speed
of rotation. The rotor of the electrical machine is connected with
a third of said components of the planetary gear so that said
third component rotates with a third speed of rotation.
The drive system comprises a control unit that is adapted to
control the electrical machine so that it provides a third compo¬
nent of the planetary gear with a speed of rotation that together
with the speed of rotation of the output shaft of the combustion
engine results in that the input shaft of the gearbox receives a
requested speed of rotation. The combustion engine comprises
an idle state and an active state, where the speed of rotation at
the idle state is lower than the speed of rotation at the active
state.
The present invention further relates to a drive system for a vehi
e according to above.
PRIOR ART
Hybrid vehicles can be operated by a primary motor that can be
a combustion engine and a secondary motor that can be an
electrical machine. The electrical machine is equipped with at
least a battery for storing electrical energy and a control equip¬
ment for controlling the flow of electrical energy between the
battery and the electrical machine. The electrical machine can
accordingly alternating work as a motor and as a generator in
dependency of the operational condition of the vehicle. When
the vehicle is slowed down, the electrical machine generates
electrical energy that is stored in the battery. The stored electri¬
cal energy is utilized later on for the operation of the vehicle.
The electrical machine can be arranged in a position between a
clutch mechanism and the gearbox in the vehicle. For reason of
limited space, it is suitable to connect the electrical machine di¬
rectly with the input shaft of the gearbox.
There are disadvantages with using a conventional clutch mechanism
that disconnects the input shaft of the gearbox from the
combustion engine during change of gear in the gearbox. When
the vehicle starts from a stand still position the discs of the
clutch mechanism glides towards each other. Accordingly, the
discs are heated up. This heat results in an increased fuel consumption
and wear of the discs of the clutch. A conventional
clutch mechanism is further relatively heavy and costly. It also
requires a relatively large space in the vehicle.
Conventional drive systems are arranged so that they only offer
a few number of operational modes that are adapted for the
main loads of the operation of the vehicle. The operation of the
vehicle by means of controlling the combustion engine and the
electrical machine are controlled based on the main operational
condition of the vehicle and with regards to maintaining charge
level of the battery of the vehicle at a certain level. The combus¬
tion engine results in noise and release of exhaust gases, which
are desirable to avoid in certain situations. For example, when
driving the vehicle inside buildings, such as a bus depot, a park¬
ing house, etcetera, or in areas where the requirement on re
lease of noise and exhaust gases are higher than what is possible
with the ordinary operation of a vehicle. It is also in certain
situation desirable to in short-terms reduce the fuel consumption
of the vehicle.
US 6,354,974 discloses a drive system for a hybrid vehicle. The
hybrid vehicle comprises a combustion engine and an electrical
machine that is arranged on the output shaft of the combustion
engine. The purpose is here to create a compact drive unit that
does not require utilizing a conventional clutch mechanism. The
conventional clutch mechanism has been replaced by a planetary
gear and three pieces of friction clutches. By means of the
friction clutches, different operational condition can be created
for the vehicle. The use of friction clutches results in energy
losses.
SUMMARY OF THE INVENTION
A first objective of the present invention is to provide a method
for controlling a drive system of a vehicle with the purpose of
allowing the vehicle to be driven in environments where noise
and exhaust level from the combustion engine are not permitted
or are not desirable, and with higher torque compared with prior
art. A second objective with the present invention is to provide a
method for controlling a drive system so that the fuel consump¬
tion temporarily is terminated. A third condition with the present
invention is to provide a method for controlling a drive system
that results in lower energy loss compared with prior art.
These objectives are achieved with the previous mentioned
method that is characterised in that the drive system comprises
a braking device (28) comprising an active state in which the
combustion engine (2) is prevented from rotating and a passive
state in which the combustion engine (2) is allowed to rotate,
that the output shaft of the combustion engine is connected to
the sun gear so that they rotate as a unit with a first speed of
rotation, that the input shaft of the gear box is connected to the
planet wheel carrier so that they rotate as a unit with a second
speed of rotation and that the rotor of the electric machine is
connected to the ring gear so that the ring gear rotates with a
third speed of rotation, the method comprising the steps:
- arranging the planetary gear in the released state, the combustion
engine in the active state, and the braking device in the ac¬
tive state,
- receiving information on a requested torque for the operation
of the vehicle, and
- controlling the electrical machine so that the requested torque
is provided while maintaining the combustion engine in the inac¬
tive state, the braking device in the active state and the plane¬
tary gear in the released state.
By arranging the combustion engine in the inactive state, the
braking device in the active state and the planetary gear in the
released state, and thereafter driving the vehicle exclusively by
means of the electrical machine, noise and exhausts gases from
the vehicle are reduced.
At pure electrical driving, the combustion engine is inactive and
the vehicle is operated only by the electrical machine. In this
driving mode, the electrical machine will be geared up according
to the transmission ratio of the planetary gear so that torque of
electrical machine is geared up to a stronger torque and the rotational
speed of the electrical machine is geared down. This is
preferable because it provides higher torque in the gearbox,
which facilitates the use of the electrical machine in its maxi¬
mum power range due to the higher rotational speed of electrical
machine. A higher speed of rotation of the electrical machine is
also favorable for reducing energy loss in the electrical machine.
The braking device is arranged in the active state with the pur¬
pose of preventing the combustion engine to rotate together with
the electrical machine when the electrical machine exclusively
provides torque for the operation of the vehicle. The combustion
engine is maintained standing still or mainly standing still by
means of the active state of the braking device. There is a risk
that the combustion engine is damaged if the combustion engine
rotates together with the electrical machine, in particularly be¬
cause the speed of rotation of the electrical machine is larger
than the speed of rotation of the combustion engine in the active
state.
By means of the method, the electrical machine allows the vehi
cle to be operated independently and without being restricted by
the combustion engine. It is therefore possible to use the higher
speed of rotation of electrical machine for the operation of the
vehicle that results in less energy loss compared with a lower
speed of rotation.
The configuration with the output shaft of the combustion engine
connected to the sun gear, the input shaft of the gearbox con¬
nected to the planet wheel carrier and the rotor of the electric
machine connected to the ring gear entails the advantage that
the combustion engine can be locked in a standing state without
the planet wheel carrier being locked. The planet wheel carrier
is thus free to rotate and thereby fatigue damages resulting from
loading the same point of the planetary wheel axles, which hap
pens if the planet wheel carrier is locked from rotation.
According to an embodiment of the invention, the planet wheel
carrier and the sun gear are locked to each other when the
planetary gear is arranged in the locked state and the planet
wheel carrier and the sun gear are released from each other
when the planetary gear is arranged in the released state.
According to an embodiment of the invention, the gearbox com¬
prises at least a forward gear and at least a reverse gear, the
method comprises:
- receiving information on if the vehicle is in a stand still state or
a movable state,
- If the vehicle is in the stand still state, the planetary gear is
arranged in the released state, the combustion engine is a r
ranged in the inactive state and the braking device in the active
state, and
- arranging the gearbox in a forward gear and the electrical ma¬
chine is controlled so that a positive torque generated, or
- arranging the gearbox in a reverse gear and the electrical ma¬
chine is controlled so that a negative torque is generated.
The method comprising that from a stand still state arranging
the gearbox in a forward gear and to control the electrical ma¬
chine so that a positive torque is generated is preferable when
the combustion engine later on is to be started. The method
comprising that from a stand still state arranging the gearbox in
a reversed gear and to control the electrical machine so that a
negative torque is generated is preferable when the combustion
engine later is to be started.
According to an embodiment of the invention, the method comprises:
- receiving information on whether the vehicle is in a stand still
state or a movable state,
- if the vehicle is in the movable state, the braking device is ar¬
ranged in the active state until the combustion engine is in a
stand still position or mainly stand still position before the plane¬
tary gear is arranged in the released state. By means of first
slowing down the combustion engine to the stand still position
before the planetary gear is opened, it is assured that the elec¬
trical machine can not rotate the combustion engine.
According to an embodiment of the invention, the method com¬
prises:
- arranging the combustion engine in the inactive state by
means of terminating feeding of fuel to the combustion engine.
According to an embodiment of the invention, the method com¬
prises:
- if the requested torque is negative when driving the vehicle
and if the operation of the vehicle exclusively with the electrical
machine is desired, the combustion engine is arranged in the
inactive state by means of terminating feeding fuel to the com¬
bustion engine and the braking device is arranged in the active
state. The combustion engine is quickly slowed down to a stand
still position by means of both terminating the feeding of fuel to
the combustion engine and arranging the braking device in the
active state. Preferably, the termination of feeding of fuel and
arranging the braking device in the active state are performed
essentially at the same time.
According to an embodiment of the invention, the gearbox com¬
prises at least a forward gear and at least a reverse gear, the
method comprises:
- arranging the planetary gear in the released state, arranging
the combustion engine in the inactive state, and arranging the
braking device in the active state,
- If the requested torque is negative when driving the vehicle,
the combustion engine is arranged in the inactive state by
means of terminating feeding of fuel to the combustion engine
and arranging the gearbox in the reverse gear. The combustion
engine is quickly slowed down to a stand still position by means
of both terminating feeding of fuel to the combustion engine and
arranging the gearbox in the reverse gear. Preferably, terminat¬
ing feeding of fuel and arranging the gearbox in the reverse
gear is done at the same time.
According to an embodiment of the invention, the gearbox com
prises at least a forward gear and at least a reverse gear, the
method comprises:
- arranging the planetary gear in the locked state, the combustion
engine in the terminated state, and the braking device in the
active state,
- if the requested torque is negative when driving the vehicle,
the combustion engine is arranged in the inactive state by
means of terminating feeding of fuel to the combustion engine
and arranging the gearbox in the reversed gear. The combustion
engine is quickly slowed down to a stand still position by means
of both terminating feeding of fuel to the combustion engine and
arranging the gearbox in the reverse gear. Preferably, the termi¬
nation of feeding fuel and arrangement of the gear box in the
reversed gear is done at the same time.
A fourth objective of the present invention is to provide a meth
od for controlling a drive system so that the fuel consumption
under certain situation is reduced. The fourth objective is
achieved by means of an embodiment of the invention in which
the drive system comprises means for determining the charge
level of the battery for the operation of the electrical machine,
wherein the method is initiated with the steps:
- receiving information on the charge level of the battery,
- determining whether the charge level of the battery exceeds a
first level,
- if the charge level of the battery exceeds the first level, the
subsequent steps in the method are performed, otherwise the
method is terminated.
The operational mode is initiated on basis of the charge level of
the battery. If the charge level of the battery exceeds a first lev¬
el, the operation is initiated where the electrical machine exclu
sively operates the vehicle. The first charge level of the battery
is preferably a level that corresponds to that the battery is essentially
fully charged, in which it is preferable to initially oper¬
ated the vehicle exclusively by means of the electrical machine.
According to an embodiment of the invention, the drive system
comprises means for determining the charge level of the battery
for operation of the electrical machine, wherein the method
comprises:
- receiving information on the charge level of the battery,
- determining whether the charge level of the battery is lower
than a second level,
- if the charge level of the battery is lower than the second level,
the method is terminated, otherwise the method is continued.
The method is terminated on basis of the charge level of the
battery. If the charge level of the battery is lower than a second
level, the operational mode is terminated where the electrical
machine exclusively operates the vehicle. The second charge
level of a battery is preferably a level where it is necessary to
charge the battery by means of energy generated from the combustion
engine.
The present invention also relates to the previously mentioned
drive system. The drive system is characterised in that the drive
system comprises a braking device comprising an active state in
which the combustion engine is prevented from rotating and a
passive state in which the combustion engine is allowed to ro¬
tate, and a control unit adapted to arrange the planetary gear in
the released state, the braking device in the active state and the
combustion engine in the inactive state, and to control the electrical
machine on basis of the requested torque while maintain¬
ing the combustion engine in the inactive state, the braking de¬
vice in the active state and the planetary gear in the released
state, the output shaft (2a) of the combustion engine being con¬
nected to the sun gear ( 10) so that they rotate as a unit with a
first speed of rotation (n1 ) , the input shaft (3a) of the gear box
being connected to the planet wheel carrier ( 12) so that they rotate
as a unit with a second speed of rotation (n2) and the rotor
(9b) of the electric machine being connected to the ring gear
( 11) so that the ring gear ( 11) rotates with a third speed of rota¬
tion (n3).
According to an embodiment of the invention, the planet wheel
carrier and the sun gear are locked to each other when the
planetary gear is arranged in the locked state and the planet
wheel carrier and the sun gear is released from each other when
the planetary gear is arranged in the released state.
According to an embodiment of the invention, the braking device
acts on any of a flywheel of the combustion engine, a shaft in
connection to the planetary gear and a third of said component
of a planetary gear. Preferably the braking device acts on the
flywheel of the combustion engine.
According to an embodiment of the invention, the braking device
comprises means for controlling the torque of the braking force
on the combustion engine or a component in connection to the
combustion engine. According to an embodiment of the inven¬
tion, the braking device is a spring loaded brake.
According to an embodiment of the invention, the braking device
is adapted to be displaced between a first position in engagement
with the combustion engine or a component in connection
with the combustion engine, and a second position without con¬
tact with the combustion engine or a component connected to
the combustion engine.
According to an embodiment of the invention, the braking device
comprises a locking pin. The locking pin enables locking of the
rotation of the combustion engine. Preferably the locking pin
acts on the flywheel of the combustion engine.
According to an embodiment of the invention, the drive system
comprises means for determining the charge level of the battery
for operating the electrical machine, wherein the control unit is
adapted to arrange the combustion engine in the inactive state,
the braking device in the active state and the planetary gear in
the released state, and to control the electrical machine under
the condition that the charge level of the battery exceeds a first
level.
According to an embodiment of the invention, the drive system
comprises means for determining the charge level of a battery
for operation of electrical machine, wherein the control unit is
adapted to arrange the combustion engine in the active state,
the braking device in the passive state and the planetary gear in
the locked state under the condition that the charge level of the
battery is lower than a second level.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, as an example, preferable embodiments of the
invention with reference to the annexed drawings will be described,
in which:
Fig. 1a discloses a drive system for operation of a vehicle ac¬
cording to the present invention.
Fig. 1b discloses the drive system in figure 1a in detail.
Fig. 2 discloses a flow chart of a method for controlling a
drive system according to a first embodiment of the invention.
Fig. 3 discloses a flow chart of a method for controlling a
drive system according to a second embodiment of the inven¬
tion.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
OF THE INVENTION
Figure 1a discloses a driveline for a heavy vehicle 1. The
driveline comprises a combustion engine 2 , a gearbox 3 , a plu¬
rality of drive shafts 4 and drive wheels 5. The drive line com¬
prises an intermediate part 6 between the combustion engine 2
and the gearbox 3.
Figure b discloses the components in the intermediate part 6 in
detail. The combustion engine 2 is provided with an output shaft
2a and the gear box 3 with an input shaft 3a in the intermediate
part 6. The output shaft 2a of the combustion engine is coaxially
arranged in relation to the input shaft 3a of the gearbox. The
output shaft 2a of the combustion engine and the input shaft 3a
of the gearbox are rotatably arranged around the axis 7 . The in¬
termediate part 6 comprises a housing 8 that encloses an elec¬
trical machine 9 and a planetary gear. The electrical machine 9
comprises in usual way a stator 9a and a rotor 9b. The stator 9a
comprises a stator core that is attached in suitable way on the
inside of the housing 8 . The stator core comprises windings of
the stator. The electrical machine 9 is adapted to during certain
operational modes utilize stored electrical energy for providing
power to the input shaft 3a of the gearbox and during other op¬
erational modes utilize kinetic energy of the input shaft 3 of the
gearbox for generating and storing electrical energy.
The planetary gear is arranged essentially radial inside of the
stator 9a and the rotor 9b of the electrical machine. The planetary
gear comprises in usual way a sun gear 10 , a ring gear 11
and a planet wheel carrier 12. The planet wheel carrier carries a
number of cog wheels 13 that are rotatable arranged in a radial
space between the cogs of the sun gear 0 and the ring gear 11.
The sun gear 10 is attached on a peripheral surface of the output
shaft 2a of the combustion engine. The sun gear 10 and the
output shaft 2a of the combustion engine rotate as a unit with a
first speed of rotation . The planet wheel carrier comprises an
attachment part 12a that is attached on a peripheral surface of
the input shaft 3a of the gearbox by means of a spline attach¬
ment 14 . By means of this attachment, the planet wheel carrier
12 and the input shaft 3a of the gearbox can rotate as a unit
with a second speed of rotation P2 · The ring gear 11 comprises
an external peripheral surface on which the rotor 9b is attached.
The rotor 9b and the ring gear 11 comprise a rotatable unit that
rotates with a third speed of rotation P3 .
The drive system comprises also locking means adapted to
switch the planetary gear between a released state in which the
sun gear 10 , the ring gear 11 and the planet wheel carrier 12
are freely rotatable in relation to each other, and a locked state
in which the planet wheel carrier 12 and the sun gear 10 are
locked to each other. The locking means are adapted in the
locked state to connect the ring gear 11 and the planet wheel
carrier 12 so that they rotate together.
The change between the locked state and the released state
comprises controlling the electrical machine 9 and the combus¬
tion engine 2 to a condition mutually free of torque and thereaf
ter displace the locking means from/to engagement with the ring
gear 11 and the planet wheel carrier 12.
The locking means comprises a displaceable connection mem¬
ber 15 on the output shaft 2a of the combustion engine. The
connection member 15 is attached on the output shaft 2a of the
combustion engine by means of a spline attachment 16. The
connection member 15 is in this case rigidly attached with re¬
gards to torsion on the output shaft 2a of the combustion engine
and displaceable arranged in an axial direction on the output
shaft 2a of the combustion engine. The connection member 15
comprises a connection part 15a that is connectable with a connecting
part 12b of the planet wheel carrier 12 . The locking
means further comprises a displacement member 17 adapted to
displace the connection member 15 between the released state
when the connection parts 15a, 12b are not in engagement with
each other and the locked state when the connection part 15a,
12b are in engagement with each other. When the connection
parts 15a, 12b are in engagement with each other, the output
shaft 2 of the combustion engine and the input shaft 3 of the
gearbox will rotate with the same speed of rotation.
An electrical control unit 18 or a plurality of electrical control
units 18 in combination are adapted to control the displacement
member 17 . The control unit 18 is also adapted to determine at
which occasion that the electrical machine 9 will work as a mo¬
tor and at which occasion it will work as a generator. To deter¬
mine this, the control unit 18 can receive immediate information
from suitable operational parameters. The control unit 18 can be
a computer with suitable software for this purpose. The control
unit 18 controls also a schematic disclosed control equipment 19
that controls the flow of electrical energy between an energy
storage 20 and the stator 9a of the electrical machine. When the
electrical machine works as a generator, electrical energy is
provided to the energy storage 20 from the stator 9a. The ener¬
gy storage 20 delivers and stores electrical energy with a volt¬
age in the range of 300-700 volt. It is necessary that the electri¬
cal machine 9 and the planetary gear compose a compact unit
because the intermediate part 6 between the combustion engine
2 and the gearbox 3 in a vehicle is limited in size. The compo¬
nents of the planetary gear 10-1 2 are here arranged essentially
radial on the inside of the stator 9a of the electrical machine.
The rotor 9b of the electrical machine, the ring gear 11 of the
planetary gear, the output shaft 2a of a combustion engine and
the input shaft 3a of the gearbox are here rotatable arranged
around a common rotation axis 5. With such arrangement, the
electrical machine 9 and the planetary gear requires a relatively
small space.
The vehicle comprises a 24 volt battery 2 1 for starting the com¬
bustion engine 2 and operation of auxiliary equipment in the ve¬
hicle 1. In heavy vehicle 1 a 24 volt battery 2 1 with a relatively
high capacity is used. The 24 volt battery 2 1 is by means of an
electrical conductor and a connection mechanism 23 connectable
with the stator 9a of electrical machine. The electrical con¬
ductor comprises a DC-DC transformer 22 between the 24 Volt
battery 2 1 and the connection mechanism 23. The DC-DC trans¬
former 22 has capacity to transform electrical energy that is
conducted from the stator 9a of electrical machine that delivers
electrical energy with the same voltage of the energy storage
20, to the voltage that prevails in the 24 voltage battery 2 1. The
DC-DC transformer 22 is preferably of two-way type. It can
thereby also when necessary conduct electrical energy from the
24 voltage battery 20 to the stator 7 of electrical machine. When
electrical energy is conducted in this direction, the DC-DC trans¬
former 22 transforms electrical energy with a voltage 24 volt to
the higher voltage of the energy storage.
The drive system comprises further a braking device 28 com¬
prising an active state and a passive state. The braking device
28 comprises a braking member that is adapted to act on a
component of the drive system so that in the active state the
output shaft 2a of the combustion engine is slowed down to a
standstill position where the output shaft 2a of the combustion
engine is prevented from rotating together with the electrical
machine. In the passive state, the braking member lacks contact
with a component of the drive system.
The braking device 28 prevents the output shaft 2a of the com¬
bustion engine to rotate with the rotation of the electrical ma¬
chine 9 when the planetary gear is in the released state and the
operation of the vehicle occurs exclusively by means of electri¬
cal machine 9 .
The braking member is displaceable between a first and a sec¬
ond position. In the first position, the braking member is in en¬
gagement with the combustion engine 2 or a component con¬
nected to the combustion engine 2 . In the second position, the
braking member lacks contact with the combustion engine 2 or a
component connected to the combustion engine 2 . Preferably
the braking member is in engagement with a flywheel of the
combustion engine 2 in the first position.
The method of the invention will be explained in detail with ref
erence to figure 2-4. The steps of the method are controlled by
means of the control unit 18 .
Figure 2 discloses a method according to a first embodiment of
the invention. The method is initiated in a step 110 by arranging
the planetary gear in the released state, the combustion engine
2 in the inactive state and the braking device 28 in the active
state. By means of the step 10 , the drive system is adapted to
be operated exclusively by means of electrical machine 9 . In this
operation mode, the electrical machine 9 will be geared up ac¬
cording to the transmission ratio of the planetary gear so that
the torque of electrical machine is geared up to a stronger
torque and the speed of rotation of electrical machine is geared
down, which results in access to a higher torque in the gearbox,
which makes it possible to use the electrical machine 9 in its
maximum power range and results in reduced energy loss of the
electrical machine 9 .
In a step 120, the control unit 18 receives information of a requested
torque for the operation of the vehicle and in a step 130
the control unit controls the electrical machine 9 so that the re¬
quested torque is provided exclusively by means of the electrical
machine 9 .
In a step 140, it is determent whether the operation of the vehi
cle is to continue exclusively by means of the electrical machine
9. If continued operation exclusively by means of electrical ma
chine 9 is desired, the method is repeated from step 120, other¬
wise the method is terminated in a step 150 by arranging the
combustion engine 2 in the active state and the braking device
28 in the passive state.
Figure 3 discloses a method according to a second embodiment
of the invention. The second embodiment differs from the first
embodiment in regards to the condition how the operation exclusively
by means of electrical machine 9 is initiated and terminat¬
ed.
The method is initiated in a step 102 by receiving information on
a charge level of the battery 20 that provides the electrical machine
9 with electrical power. In a step 105, it is determent
whether the charge level exceeds a first level. If the charge lev¬
el exceeds the first level, the method is continued according to
step 120-1 50. If on the other hand the charge level does not ex¬
ceed a first level, the method is terminated.
The method is terminated in a step 132 by receiving information
on the charge level of a battery 20 that provides the electrical
machine 9 with electrical power. In a step 135, it is determined
whether the charge level is lower than a second level. If the
charge level is lower than the second level the method is termi¬
nated in a step 150 in the same manner as in figure 2. If on the
other hand the charge level is not lower than the second level,
the method continues according to step 120-1 35.
At operation exclusively by means of electrical machine 9 , the
combustion engine 2 must be slowed down/locked so that the
reaction torque from the planetary gear does not make it rotate
forward or backwards. It would then be no limit to how fast the
combustion engine 2 could rotate and the combustion engine 2
could be damaged. Furthermore, friction losses would be creat¬
ed in the combustion engine 2 .
The braking of the combustion engine 2 can be realized by a
controllable braking device 28 that is torque controlled, a spring
loaded braking device 28 with a constant brake torque or any
types of locking pin. The braking device 28 can act on the fly¬
wheel of the combustion engine, on the shaft to the planetary
gear or on the sun gear of a planetary gear.
There are a number of ways to switch to pure electrical driving.
From a standing still position by means of that the combustion
engine 2 is slowed down, the planetary gear is in the released
state, the gearbox is arranged with a forward gear, wherein a
positive torque is controlled to the electrical machine 9. This
mode is preferable when it is necessary to choose between different
gears during driving. Alternatively from a standing still
state by means of that the combustion engine 2 is slowed down,
the planetary gear is in the released state, the gearbox is ar¬
ranged in a reversed gear, wherein a negative torque is con¬
trolled to the electrical machine 9 . This mode of driving is preferable
when the combustion engine later is to be started.
There are a number of ways to switch to pure electrical driving.
From a position in which the vehicle is driven with the planetary
gear in the locked state by arranging the planetary gear in the
released state, the combustion engine 2 is slowed down until it
is stopped. At positive drive line torque, the combustion engine
2 is slowed down preferably to a stand still position by terminat¬
ing feeding of fuel into the engine. At negative drive line torque,
the combustion engine 2 is slowed down preferably to a stand
still position by terminating feeding of fuel and to apply the brak¬
ing device 28, alternatively to change gear to a reversed gear
and terminate feeding fuel. The same method is possible from a
position in which the vehicle is driven with the planetary gear in
an open state with the difference that the planetary gear no
longer needs to be changed.
The invention is not limited to the disclosed embodiments but
can be modified and varied within the framework of the following
claims. It is for example possible to combine the features in the
two embodiments to a separate embodiment.
WE CLAIMS:-
1. Method for controlling a drive system of a vehicle, the
drive system comprises a combustion engine (2) with an output
shaft (2a), a gearbox (3) with an input shaft (3a), an electrical
machine (9) that comprises a stator (9a) and a rotor (9b), and a
planetary gear that comprises three components in the form of a
sun gear ( 10), a ring gear ( 11) and a planet wheel carrier ( 12),
wherein the output shaft (2a) of the combustion engine is connected
with a first of said components of the planetary gear so
that a rotation of this shaft results in a rotation of this compo¬
nent, wherein the input shaft (3a) of the gearbox is connected
with a second of said components of the planetary gear so that
a rotation of this shaft results in a rotation of this component
and the rotor (9b) of the electrical machine is connected with a
third of said components of the planetary gear so that a rotation
of the rotor results in a rotation of this component, and wherein
the drive system further comprises locking means transferable
between a locked state in which two of said components are
locked together so that the three components ( 10-1 2) rotate with
the same speed of rotation and a released state in which the
components are allowed to rotate with different speed of rota¬
tion, wherein the combustion engine (2) comprises an active
state and an inactive state,
characterised in that
the drive system comprises a braking device (28) comprising an
active state in which the combustion engine (2) is prevented
from rotating and a passive state in which the combustion en¬
gine (2) is allowed to rotate, that the output shaft (2a) of the
combustion engine is connected to the sun gear ( 10) so that
they rotate as a unit with a first speed of rotation (n1 ) , that the
input shaft (3a) of the gear box is connected to the planet wheel
carrier ( 12) so that they rotate as a unit with a second speed of
rotation (n2), and that the rotor (9b) of the electrical machine is
connected to the ring gear ( 1 1) so that the ring gear ( 11) rotates
with a third speed of rotation (n3), the method comprising the
steps:
- arranging the planetary gear in the released state, the combus¬
tion engine (2) in the inactive state, and the braking device (28)
in the active state,
- receiving information on a requested torque for the operation
of the vehicle, and
- controlling the electrical machine (9) so that the requested
torque is provided while maintaining the combustion engine (2)
in the inactive state, the braking device (28) in the active state
and the planetary gear in the released state.
2 . Method for controlling a drive system according to
claim 1, wherein the planet wheel carrier ( 12) and the sun gear
( 10) are locked to each other when the planetary gear is ar¬
ranged in the locked state and the planet wheel carrier ( 12) and
the sun gear ( 10) are released from each other when the plane¬
tary gear is arranged in the released state.
3 . Method for controlling a drive system according to any
of the previous claims, wherein the method comprises:
- arranging the combustion engine (2) in the inactive state by
means of terminating feeding of fuel to the combustion engine
(2).
4 . Method for controlling a drive system according to any
of the previous claims, wherein the method comprises:
- if the requested torque is negative when driving the vehicle
and if the operation of the vehicle by means of the electrical
machine is desired, the combustion engine (2) is arranged in the
inactive state by means of terminating feeding of fuel to the
combustion engine (2).
5. Method for controlling a drive system according to any
of the previous claims, wherein the gearbox (3) comprises at
least a forward gear and at least a reverse gear, the method
comprises:
- receiving information on if the vehicle is in a standing still state
or in a movable state,
- if the vehicle is in the standing still state, the planetary gear is
arranged in the released state, the combustion engine (2) is ar¬
ranged in the inactive state, and the braking device in the active
state, and
- arranging the gearbox in a forward gear and the electrical machine
is controlled to generate a positive torque, or
- arranging the gearbox in a reversed gear and the electrical
machine is controlled to generate a negative torque.
6. Method for controlling a drive system according to any
of the previous claims, wherein the drive system comprises
means for determining the charge level of a battery (20) for the
operation of electrical machine (9), wherein the method is init i
ated with the steps:
- receiving information on the charge level of the battery (20),
- determining if the charge level of the battery (20) exceeds a
first level,
- if the charge level of the battery (20) exceeds the first level,
the remaining steps of the method are performed, otherwise the
method is terminated.
7 . Method for controlling a drive system according to any
of the previous claims, wherein the drive system comprises
means for determining the charge level of a battery (20) for the
operation of the electrical machine (9), wherein the method
comprises:
- receiving information on the charge level of the battery (20),
- determining whether the charge level of the battery (20) is
lower than a second level,
- if the charge level of the battery (20) is lower than the second
level, the method is terminated, otherwise the method is cont in
ued.
8 . Method for controlling a drive system according to any
of the previous claims, wherein the method is terminated by the
steps:
- arranging the braking device (28) in the passive state and a r
ranging the combustion engine (2) in the active state.
9 . Drive system for a vehicle, the drive system comprises
a combustion engine (2) with an output shaft (2a), a gearbox (3)
with an input shaft (3a) and an electrical machine (9) that com
prises a stator (9a) and a rotor (9b), and a planetary gear that
comprises three components in the form of a sun gear ( 10), a
ring gear ( 11) and a planet wheel carrier ( 12), wherein the out
put shaft (2a) of the combustion engine is connected with a first
of said components of the planetary gear so that a rotation of
this shaft results in a rotation of this component, wherein the in¬
put shaft (3a) of the gearbox is connected with a second of said
components of the planetary gear so that a rotation of this shaft
results in a rotation of this component and the rotor (9b) of the
electrical machine is connected with a third of said components
of a planetary gear so that the rotation of the rotor results in a
rotation of this component, and wherein the drive system further
comprises locking means transferable between a locked state in
which two of said components are locked together so that the
three components ( 10-1 2) rotate with the same speed of rotation
and a released state in which the components are allowed to ro
tate with different speed of rotation, wherein the combustion en¬
gine (2) comprises an active state and an inactive state,
characterised in that
the drive system comprises a braking device (28) comprising an
active state in which the combustion engine (2) is prevented
from rotating and a passive state in which the combustion e n
gine (2) is allowed to rotate, and a control unit ( 18) adapted to
arrange the planetary gear in the released state, the braking device
(28) in the active state and the combustion engine (2) in the
inactive state, and to control the electrical machine (9) on basis
of the requested torque while maintaining the combustion engine
(2) in the inactive state, the braking device (28) in the active
state and the planetary gear in the released state, the output
shaft (2a) of the combustion engine being connected to the sun
gear ( 10) so that they rotate as a unit with a first speed of rota¬
tion (n1 ) , the input shaft (3a) of the gear box being connected to
the planet wheel carrier ( 12) so that they rotate as a unit with a
second speed of rotation (n2), and the rotor (9b) of the electric
machine being connected to the ring gear ( 11) so that the ring
gear ( 1 ) rotates with a third speed of rotation (n3), .
10 . Drive system for a vehicle according to claim 9 ,
wherein the planet wheel carrier ( 12) and the sun gear ( 10) are
locked to each other when the planetary gear is arranged in the
locked state and the planet wheel carrier ( 12) and the sun gear
( 10) are released from each other when the planetary gear is
arranged in the released state.
1 . Drive system for a vehicle according to any of claims
9-1 0 , wherein the braking device (28) acts on any of a flywheel
of the combustion engine (2), a shaft in connection to the plane¬
tary gear and the third of said components ( 1) of the planetary
gear.
12. Drive system for a vehicle according to any of claims
9-1 1, wherein the braking device (28) comprises a braking
member adapted to be displaced between a first position in en¬
gagement with the combustion engine (2) or a component con
nected to the combustion engine (2), and a second position
without contact with the combustion engine (2) or a component
in connection to the combustion engine (2).
3. Drive system for a vehicle according to any of claims
9-1 2 , wherein the drive system comprises means for determining
the charge level of a battery (20) for the operation of the electri¬
cal machine (9), wherein the control unit ( 18) is adapted to arrange
the combustion engine (2) in the inactive state, the brak¬
ing device (28) in the active state and the planetary gear in the
released state, and to control the electrical machine (9) on con¬
dition that the charge level of the battery (20) exceeds a first
level.
14. Drive system for a vehicle according to any of claims
9-1 3 , wherein the drive system comprises means for determining
the charge level of a battery (20) for the operation of the electrical
machine (9), wherein the control unit ( 18) is adapted to a r
range the combustion engine (2) in the active state, the braking
device (28) in the passive state and the planetary gear in the
locked state on condition that the charge level of the battery
(20) is lower than a second level.
15. Computer program comprising computer program code
for a computer to implement a method according to any of
claims 1-8 when the computer program code is executed in the
computer.
16 . Computer program product comprising a data storage
medium that is readable by a computer, wherein the computer
program code of a computer program according to claim 15 is
stored on the data storage medium.
17 . Vehicle comprising a drive system according to any of
claims 9-1 4.
