HYDRAULIC COUPLING HAVING SELF-ADJUSTING
ANTI-ROTATION HYDRAULIC FLUID PATH
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates, generally, to hydraulic couplings and, more
specifically, to a hydraulic coupling having a self-adjusting fluid delivery path with antirotational
capabilities.
2. Description of the Related Art
[0002] Hydraulic couplings are well-known devices used in vehicle drive trains.
Typically, hydraulic couplings are operatively supported within a housing and are in fluid
communication with a source of hydraulic fluid. These devices operate to couple a pair of
rotating members, such as drive shafts or axle half shafts about a rotational axis. Thus, hydraulic
couplings have been employed as a part of transfer cases that operatively couple the front and
rear axles of a vehicle, in limited slip and locking differentials used to couple axle half shafts, as
well as other applications commonly known in the art.
[0003] Hydraulic couplings of the type known in the related art may include a gear box
supported by the housing and that include a gear set designed to allow for relative rotation
between the rotary members coupled together by the hydraulic coupling. In addition, these
devices also include a coupling mechanism, such as a clutch pack, that operate to lock the rotary
members for rotation together. Hydraulic fluid is used to actuate a piston or a like device to
engage the clutch and therefore couple the rotating members together. Typically, the gear box is
supported for rotation within the housing, but the coupling mechanism is not. Rather, the
coupling mechanism may be supported upon one of the rotary members via roller bearings or the
like. Nevertheless, because it is supported upon a rotary member and usually adjacent the
rotating gear box, and because it acts to couple the rotary members together, the coupling
mechanism is subjected to torque during normal operating conditions. When the source of
pressurized hydraulic fluid is located outside of the coupling mechanism, for example, it must be
delivered through the stationary housing to the coupling mechanism. There are generally two
ways to deliver pressurized fluid in these circumstances.
[0004] One approach is to use a flexible tube that may be bent or flexed to establish the
fluid connection between the outer housing and the coupling mechanism. However, this
approach suffers from the disadvantage that there is no "anti-rotation" feature of the tube.
Accordingly, where flexible tubing is employed, the hydraulic coupling must also include antirotation
tabs or special mounting structure that is used to stabilize the coupling mechanism
relative to the gear box as well as the outer housing. This necessitates that the coupling
mechanism as well as the gear box be assembled in a particular way to align these component
parts of the hydraulic coupling in a particular way. This increases the complexity of the
hydraulic couplings known in the related art as well as the cost of manufacturing them.
[0005] Another approach for delivering pressurized hydraulic fluid to the coupling
mechanism is to employ a rigid tube that extends from the outer housing to the coupling
mechanism. A rigid tube provides anti-rotational aspects to the system and helps the coupling
mechanism resist torque imposed through this system. However, because this approach is also
"rigid" all associated apertures and mounting points for the fluid path must be very accurately
located. Slight deviations from design in the location of the aperture can create difficulties
during the manufacturing process. This increases the cost associated with manufacturing both
the housing as well as the coupling mechanism. In addition, it also complicates the assembly of
the device.
[0006] Thus, there remains a need in the art for a hydraulic coupling having a fluid path
that is flexible and self-adjusting such that the corresponding apertures formed in the housing as
well as the coupling mechanisms do not have to be located with extreme precision. In addition,
there remains a need in the art for a hydraulic coupling having a fluid path that has anti-rotational
aspects so as to eliminate the need for anti-rotation tabs or other specific mechanisms used to
mount the coupling mechanism to the housing. In addition, there remains a need in the art for a
hydraulic coupling having a fluid path that allows for significant misalignment between the
interior mounting points and the exterior mounting points for the fluid path.
SUMMARY OF THE INVENTION
[0007] The present invention overcomes the disadvantages in the related art in a
hydraulic coupling for use in a vehicle drive train including a pair of rotary members. The
hydraulic coupling includes a housing that is in fluid communication with a source of pressurized
fluid. A gear case is supported for rotation by the housing and is operatively coupled to the
rotary members. A coupling mechanism is non-rotatably supported within the housing and
adjacent the gear case. The coupling mechanism is operable to selectively couple the pair of
rotary members together. A fluid path extends between the housing and the coupling
mechanism. The fluid path includes a first aperture formed in the housing and having a first
diameter and a longitudinal axis, as well as a second aperture formed in the coupling mechanism.
A rigid conduit having a first portion extends through the first aperture in the housing with a
diameter less than the first diameter of the first aperture so as to define an adjustment gap so that
the rigid conduit can move out of alignment with the longitudinal axis in response to a
misalignment between the first and second apertures. I addition, the rigid conduit includes a
second portion that is sealingly received in frictional engagement with the second aperture in the
coupling mechanism such that the rigid conduit provides resistance to torque imposed upon the
coupling mechanism.
[0008] In this way, the hydraulic coupling of the present invention provides a fluid path
that is flexible and self-adjusting such that corresponding apertures formed in the housing as well
as the coupling mechanism do not have to be located with extreme precision. In addition, the
hydraulic coupling of the present invention has a fluid path that has anti-rotational aspects so as
to eliminate the need for anti-rotation tabs or other specific mechanisms used to mount the
coupling mechanism to the housing. Thus, the hydraulic coupling of the present invention has a
fluid path that allows for significant misalignment between the interior mounting points and the
exterior mounting points for the fluid path while at the same time providing anti-rotational
features thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Other objects, features and advantages of the present invention will be readily
appreciated, as the same becomes better understood after reading the subsequent description
taken in connection with the accompanying drawings wherein:
[0010] Figure 1 is a cross-sectional side view of the hydraulic coupling of the present
invention;
[0011] Figure 2 is a partial cross-sectional side view of the hydraulic coupling of the
present invention illustrating the coupling mechanism and the fluid path;
[0012] Figure 3 is an enlarged cross-sectional side view of the fluid path of the present
invention; and
[0013] Figure 4 is an enlarged cross-section of the fluid path of the present invention
illustrating the rigid conduit in a skewed position.
DETAILED DESCRIPTION
[0014] A representative example of a hydraulic coupling for use in a vehicle drive train is
generally indicated at 10 in Figure 1, where like numerals are used to designate like structure
throughout the drawings. Those having ordinary skill in the art will recognize that hydraulic
couplings may be employed as a part of transfer cases that operative ly couple the front and rear
axles of a vehicle; as a part of limited slip, or locking differentials used to couple axle half shafts;
as well as other applications in vehicle drive trains as is commonly known in the art. Thus, those
having ordinary skill in the art will appreciate from the description that follows that the purpose
of the figures is to illustrate one example of the present invention, and are not meant to limit it.
[0015] As noted above, the hydraulic coupling 10 is used in a vehicle drive train that
includes a pair of rotary members. To this end, the hydraulic coupling includes a housing, on
one half of which is generally indicated at 12, that is in fluid communication with a source of
pressurized fluid, schematically illustrated at 14 in Figures 1-2. The source of pressurized fluid
14 may include a primary pump used to lubricate and cool various components of the vehicle
drive train or any other suitable source of pressurized hydraulic fluid as is commonly known in
the art. A gear case, generally indicated at 16, is supported for rotation within the housing 14.
To this end, the gear case may be driven through a pinion gear by a drive axle or a vehicle prop
shaft, as the case may be. A pair of side gears 18, 20 is also mounted for rotation with respective
ones of the rotary members in the gear case 16. Thus, each of the pair of side gears 18, 20
includes a splined inner diameter 22, 24 that is adapted to cooperate with corresponding splines
(not shown) on the rotary members.
[0016] In the representative example illustrated in these figures, the hydraulic coupling
10 also functions as a differential. However, and as noted above, the hydraulic coupling 10 of
the present invention is not limited to this particular application. In any event, a cross pin 26 is
fixedly mounted to the gear case 16 for rotation therewith. A pair of pinion gears 28 are
mounted for rotation on the cross pin and in meshing relationship with gear teeth formed on each
of the pair of side gears 18, 20. The side gears 18, 20 and pinion gears 28 cooperate to provide
differential rotation between the rotary members as is commonly known in the art.
[0017] In addition, the hydraulic coupling 10 of the present invention includes a coupling
mechanism, generally indicated at 30, that is non-rotatably supported within the housing 12 and
adjacent to the gear case 16. The coupling mechanism 30 is operable to selectively couple the
pair of rotary members together. In this context, the hydraulic coupling 10 of the present
invention may embody a limited slip differential or a locking differential. Thus, the coupling
mechanism 10 of the present invention may be operable to allow relative rotation between the
pair of rotary members under certain circumstances and then act to lock the rotary members
together under other operational conditions.
[0018] To this end, the hydraulic coupling 10 of the present invention also includes a
clutch assembly, generally indicated at 32, having an open position wherein the side gears 18, 20
may rotate at different speeds and a closed position wherein the hydraulic coupling 10 is locked
so that the side gears 18, 20 rotate at substantially the same speed. The coupling mechanism 30
includes a housing 34 and a piston 36 movably supported within the housing 34. The piston 36
and the housing 34 act to define an expandable chamber 38 therebetween. The expandable
chamber 38 is in fluid communication with the source of pressurized fluid 14 as will be described
in greater detail below. The housing 34 of the coupling mechanism 30 may also include a purge
fitting 40 that is employed for a one-time purging of air when the system is initially charged as is
commonly known in the art.
[0019] More specifically, the clutch assembly 32 includes a plurality of annular plates 42
that are splined at their outer diameter to the gear case 16. In addition, the clutch assembly 32
includes a plurality of annular friction disks 44 that are splined at their inner diameter to one of
the pair of side gears 18 or 20. In the representative example illustrated herein, the annular
friction disks 44 are splined at their inner diameter to the side gear 20. However, those having
ordinary skill in the art will appreciate that the annular friction disks 44 may be supported for
rotation by either of the side gears 18 or 20, or both. The plurality of annular plates 42 and
annular friction disks 44 are interleaved between one another and act to rotate past one another in
substantially non-contacting relationship when the clutch assembly 32 is in its open position. On
the other hand, the annular plates 42 and friction disks 44 are axially movable upon their splined
interconnections into frictional engagement relative to one another thereby reducing relative
rotation between the annular plates 42 and disks 44 when the clutch assembly 32 is in its closed
position. Thus, when the clutch assembly 32 is in its closed position, the side gears 18, 20 rotate
together.
[0020] The clutch assembly 32 includes a transfer pin 46 that extends between the piston
36 and the plurality of interleaved annular plates 42 and friction disks 44. The transfer pin 46 is
responsive to movement of the piston 36 to move the clutch assembly 32 from its open position
to its closed position as will be described in greater detail below.
[0021] The hydraulic coupling 10 of the present invention also includes a fluid path,
generally indicated at 48, that is in communication with the source of pressurized fluid 14 and
that extends between the housing 12 and the coupling mechanism 30. As best shown in Figures
3 and 4, the fluid path 48 includes a first aperture, generally indicated at 50, formed in the
housing 12 and having a first diameter and a longitudinal axis A. In addition, the fluid path 48
includes a second aperture 52 that is formed in the coupling mechanism 30. A rigid conduit 54
extends between the first aperture 50 and the second aperture 52 as is described in greater detail
below.
[0022] More specifically, the rigid conduit 54 has a first portion 56 that extends through
the first aperture 50 in the housing 12 and has a diameter that is less than the first diameter of the
first aperture 50. Thus, the first portion 56 of the rigid conduit and the first diameter of the first
aperture 50 define an adjustment gap G. This gap G facilitates the rigid conduit's 54 movement
out of alignment with the longitudinal axis A in response to a misalignment between the first and
second apertures 50, 52 as shown in Figure 4. The rigid conduit 54 also includes a second
portion 58 that is sealingly received in frictional engagement with the second aperture 52 in the
coupling mechanism 30. Because of its relative stiffness, the rigid conduit 54 provides resistance
to torque imposed on the coupling mechanism 30, as will be described in greater detail below.
[0023] With continuing reference to Figures 3 and 4, the first aperture 50 in the housing
12 includes an inlet 60 and an outlet 62 with the longitudinal axis A extending therebetween.
The housing 12 also includes a pre-chamber 64 having a base 66 that is defined adjacent to the
inlet 60 of the first aperture 50. The pre-chamber 64 has a diameter that is greater than the first
diameter of the first aperture 50. The rigid conduit 54 includes a head portion 68 that is received
in the pre-chamber 64 in abutting relationship with the base 66 and adjacent to the inlet 60 to the
first aperture. More specifically, the first portion 56 of the rigid conduit 54 includes an annular
shoulder 70 and a sealing member 72 disposed between the annular shoulder 70 and the housing
12. The shoulder 70 extends annularly about the head portion 68 of the rigid conduit 54. The
shoulder 70 defines an annular, U-shaped cavity 74. The sealing member 72 may include an Oring,
gasket, or the like that is received in the annular U-shaped cavity 74 and disposed in sealing
relationship with the base 66 of the pre-chamber 64. To this end, the fluid path 48 may also
include a fastener 76 that is disposed about the shoulder 70 opposite the sealing member 72 so as
to fix the head 68 and the shoulder 70 in abutting and sealing contact with the base 66 of the prechamber
64. The fastener 76 may be selected from a group including a snap ring, jam nut, press
fit ring or the like. However, those having ordinary skill in the art will recognize that any
suitable fastener commonly known in the related art may be employed for this purpose.
[0024] The fluid path 48 also includes at least one sealing member 78 that is disposed
between the second portion 58 of the rigid conduit 54 and the second aperture 52 formed in the
coupling mechanism 30. More specifically, and in the representative embodiment illustrated
herein, the sealing member may include a series of sealing members 78 that are disposed in
longitudinal spaced relationship with respect to each other about the outer circumference of the
second portion 58 of the rigid conduit 54. To this end, the second aperture 52 may include a
series of annular grooves 80 with each of the sealing members 78 disposed in the annular
grooves 80 in abutting sealing contact with the second portion 58 of the rigid conduit 54. The
second aperture 52 establishes fluid communication between the expandable chamber 38 and the
source of pressurized fluid 14. Thus, the piston 36 is movable in response to a bias created by
the pressurized fluid in the expandable chamber 38 from a first position wherein the clutch
assembly 32 is in its opened position and a second position wherein the piston 36 moves the
transfer pin 46 and thus the clutch assembly 32 to its closed position so that the side gears 18, 20
rotate together.
[0025] Because of the adjustment gap defined between the first portion 56 of the rigid
conduit 54 and the first aperture 50, the fluid path 48 of the present invention is flexible and selfadjusting.
In this way, the first and second apertures 50, 52 formed in the housing 12 and the
coupling mechanism 30 do not have to be located with extreme precision. This adjustment
capability is best illustrated in Figure 4 where the rigid conduit 54 is shown skewed relative to
the longitudinal axis A. In this way, the hydraulic coupling 10 of the present invention having a
fluid path 48 that allows for significant misalignment between the interior mounting points and
the exterior mounting points of the fluid path 48 significantly reduces the cost of manufacture of
this device. In addition, because the conduit 54 is rigid, the fluid path established between the
first and second apertures 50, 52 resists relative rotation of the housing 34 of the coupling
mechanism 30 relative to the gear case 16. Accordingly, this feature acts to eliminate the need
for anti-rotation tabs or other specific mechanisms used to mount the coupling mechanism 30 to
the housing 12. In this way, the cost to manufacture the hydraulic coupling 10 of the present
invention is further reduced.
[0026] The invention has been described in great detail in the foregoing specification,
and it is believed that various alterations and modifications of the invention will become
apparent to those having ordinary skill in the art from a reading and understanding of the
specification. It is intended that all such alterations and modifications are included in the
invention, insofar as they come within the scope of the appended claims.
I CLAIM:
1. Ahydraulic coupling (10) for use in a vehicle drive train including a pair of rotary
members, said hydraulic coupling comprising:
a housing (12) in fluid communication with a source of pressurized fluid (14);
a gear case (16) supported for rotation by said housing (12) and operatively coupled to
the rotary members;
a coupling mechanism (30) non-rotatably supported within said housing (12) and adjacent
said gear case (16), said coupling mechanism (30) operable to selectively couple the pair of
rotary members together;
a fluid path (48) extending between said housing (12) and said coupling mechanism (30),
said fluid path (48) including a first aperture (50) formed in said housing (12) and having a first
diameter and a longitudinal axis (A), a second aperture (52) formed in said coupling mechanism
(30), a rigid conduit (54) having a first portion (56) extending through said first aperture (50) in
said housing (12) and having a diameter less than said first diameter of said first aperture (50) so
as to define an adjustment gap (G) such that said rigid conduit (54) can move out of alignment
with said longitudinal axis (A) in response to a misalignment between said first and second
apertures (50, 52), and a second portion (58) that is sealingly received in frictional engagement in
said second aperture (52) in said coupling mechanism (30) such that said rigid conduit (54)
provides resistance to torque imposed upon said coupling mechanism (30).
2. A hydraulic coupling (10) as set forth in claim 1wherein said first aperture (50)
includes an inlet (60) and an outlet (62) with said longitudinal axis (A) extending therebetween.
3. A hydraulic coupling (10) as set forth in claim 2 wherein said housing (12)
includes a pre-chamber (64) having a base (66) defined adjacent said inlet (60) to said first
aperture (50), said pre-chamber (64) having a diameter greater than said first diameter of said
first aperture (50).
4. A hydraulic coupling (10) as set forth in claim 3 wherein said rigid conduit (54)
includes a head portion (68) received in said pre-chamber (64) in abutting relationship with said
base (66) and adjacent said inlet (60) to said first aperture (50).
5. A hydraulic coupling (10) as set forth in claim 4 wherein said first portion (56) of
said rigid conduit (54) includes an annular shoulder (70) and a sealing member (72) disposed
between said annular shoulder (70) and said housing (12).
6. A hydraulic coupling (10) as set forth in claim 5 wherein said shoulder (70)
extends annularly about said head portion (68) of said rigid conduit (54).
7. A hydraulic coupling (10) as set forth in claim 6 further including a fastener (76)
disposed about said shoulder (70) opposite said sealing member (72) so as to fix said head
portion (68) and said shoulder (70) in abutting and sealing contact with said annular base (66) of
said pre-chamber (64).
8. A hydraulic coupling (10) as set forth in claim 7 wherein said shoulder (70)
defines a annular, U-shaped cavity (74), said sealing member (72) including an O-ring received
within said annular U-shaped cavity (74) and disposed in sealing relationship with said base (66)
of said pre-chamber (64).
9. A hydraulic coupling (10) as set forth in claim 7 wherein said fastener (76) may
be selected from a group including a snap ring, jam nut and press fit ring.
10. A hydraulic coupling (10) as set forth in claim 1 wherein said fluid path (48)
includes at least one sealing member (78) disposed between said second portion (58) of said rigid
conduit (54) and said second aperture (52) formed in said coupling mechanism (30).
11. A hydraulic coupling (10) as set forth in claim 10 wherein said at least one sealing
member (78) includes a series of sealing members disposed in longitudinally spaced relationship
with respect to each other about the outer circumference of said second portion (58) of said rigid
conduit (54).
12. A hydraulic coupling (10) as set forth in claim 11wherein said second aperture
(52) includes a series of annular grooves (80), said series of sealing members (78) disposed in
said annular grooves (80) in abutting sealing contact with said second portion (58) of said rigid
conduit (54).
13. A hydraulic coupling (10) as set forth in claim 1 further including a pair of side
gears (18, 20) mounted for rotation with a respective one of the rotary members in said gear case
(16) and a clutch assembly (32) having an open position wherein said side gears (18, 20) may
rotate at different speeds and a closed position wherein said hydraulic coupling (30) is locked so
that side gears (18, 20) rotate at substantially the same speed.
14. A hydraulic coupling (10) as set forth in claim 13 wherein said coupling
mechanism (30) includes a housing (34) and a piston (36) movably supported within said
housing (34) and defining an expandable chamber (38) between said piston (36) and said housing
(34), said second aperture (52) establishing fluid communication between said expandable
chamber (38) and the source of pressurized fluid (14), said piston (36) movable in response to a
bias created by the pressurized fluid in said expandable chamber (38) from a first position
wherein said clutch assembly (32) is in its open position and a second position wherein said
piston (36) moves said clutch assembly (32) to its closed position so that said side gears (18, 20)
rotate together.
15. A hydraulic coupling (10) as set forth in claim 14 wherein said clutch assembly
(32) includes a plurality of annular plates (42) splined to said gear case (16) and a plurality of
annular friction disks (44) splined to one of said pair of side gears (18, 20) and interleaved
between said plurality of annular plates (42), said annular plates (42) and annular friction disks
(44) act to rotate past one another in substantially non-contacting relationship when said clutch
assembly (32) is in its opened position and said annular plates (42) and friction disks (44) being
axially movable into frictional engagement relative to one another thereby reducing relative
rotation between said annular plates and disks when said clutch assembly (32) is in its closed
position.
16. A hydraulic coupling (10) as set forth in claim 15 wherein said clutch assembly
(32) includes a transfer pin (46) extending between said piston (36) and said plurality of
interleaved annular plates and friction disks, said transfer pin (46) responsive to movement of
said piston (36) to move said clutch assembly (32) from its opened position to its closed position.
17. A hydraulic coupling (10) as set forth in claim 13 wherein said gear case (16)
includes a cross pin (26) fixedly mounted to said gear case (16) for rotation therewith and a pair
of pinion gears (28) mounted for rotation on said cross pin (26) and in meshing relationship with
each of said pair of side gears (18, 20).
18. Ahydraulic coupling (10) for use in a vehicle drive train including a pair of rotary
members, said hydraulic coupling comprising:
a housing (12) in fluid communication with a source of pressurized fluid (14);
a gear case (16) supported for rotation by said housing (12), a pair of side gears (18, 20)
mounted for rotation with the respective one of the rotary members in said gear case ( 16), a cross
pin (26) fixedly mounted to said gear case (16) for rotation therewith and a pair of pinion gears
(28) mounted for rotation on said cross pin (26) and in meshing relationship with each of said
pair of side gears (18, 20), said side gears and pinion gears cooperating to provide differential
rotation between the pair of rotary members;
a coupling mechanism (30) non-rotatably supported within said housing (12) and adjacent
said gear case (16), said coupling mechanism (30) operable to selectively couple the pair of
rotary members together;
a fluid path (48) extending between said housing (12) and said coupling mechanism (30),
said fluid path (48) including a first aperture (50) formed in said housing (12) and having a first
diameter and a longitudinal axis (A), a second aperture (52) formed in said coupling mechanism
(30), a rigid conduit (54) having a first portion (56) extending through said first aperture (50) in
said housing (12) and having a diameter less than said first diameter of said first aperture (50) so
as to define an adjustment gap (G) such that said rigid conduit (54) can move out of alignment
with said longitudinal axis (A) in response to a misalignment between said first and second
apertures (50, 52), and a second portion (58) that is sealingly received in frictional engagement in
said second aperture (52) in said coupling mechanism (30) such that said rigid conduit (54)
provides resistance to torque imposed upon said coupling mechanism (30).
19. A hydraulic coupling (10) as set forth in claim 18 wherein said first aperture (50)
includes an inlet (60) and an outlet (66) with said longitudinal axis (A) extending therebetween,
said housing (12) including a pre-chamber (64) having a base (66) defined adjacent said inlet
(60) to said first aperture (50), said pre-chamber (64) having a diameter greater than said first
diameter of said first aperture (50), said rigid conduit (54) including a head portion (68) received
in said pre-chamber (64) in abutting relationship with said base (66) and adjacent said inlet (60)
to said first aperture (50).
20. A hydraulic coupling (10) as set forth in claim 19 wherein said first portion of
said rigid conduit (54) includes an annular shoulder (70) extending about said head portion (68)
of said rigid conduit (54), and defining an annular, U-shaped cavity (74), a sealing member (72)
disposed within said U-shaped cavity (74) between said annular shoulder (70) and said housing
(12) and disposed in sealing relationship with said base (66) of said pre-chamber (64).