Patent Application
20160084365
The present disclosure relates generally to differential assemblies and, more particularly, to a hydraulic power supply configuration on a rear wheel drive electronic limited slip differential.
Differentials are provided on vehicles to permit an outer drive wheel to rotate faster than an inner drive wheel during cornering as both drive wheels continue to receive power from the engine. While differentials are useful in cornering, they can allow vehicles to lose traction, for example, in snow or mud or other slick mediums. If either of the drive wheels loses traction, it will spin at a high rate of speed and the other wheel may not spin at all. To overcome this situation, limited-slip differentials were developed to shift power from the drive wheel that has lost traction and is spinning, to the drive wheel that is not spinning.
Electronically-controlled, limited-slip differentials can include a hydraulically-actuated clutch to limit differential rotation between output shafts of the differential. The hydraulically-actuated clutch, however, must be powered by a separate pump. In addition to the extra cost associated with providing a separate pump as described, such pumps can introduce parasitic energy losses that can negatively impact vehicle fuel economy and vehicle operation. For at least these reasons, an improved differential is desired.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A cover for a differential housing can include a body, a flange, a fluid reservoir, a first fluid conduit, and second fluid conduit. The body can have an inwardly-facing surface and outwardly-facing surface opposite the inwardly-facing surface. The flange can extend about at least a portion of a perimeter of the body. The fluid reservoir can be defined within the body and have a reservoir outlet and a return port. The first fluid conduit can be defined within the body. The first fluid conduit can be spaced from the fluid reservoir and extend between a first inlet and a first outlet. The second fluid conduit can be defined within the body and extend between the first fluid conduit and the return port of the fluid reservoir.
According to other features, the cover can include a three-way valve positioned at an intersection of the first fluid conduit and the second fluid conduit. The three-way valve can be operable in a first setting and a second setting. In the first setting, fluid passage between the first inlet and the first outlet can be permitted and fluid passage along the second fluid conduit can be prevented. In the second setting, fluid passage between the first inlet and the first outlet can be prevented and fluid passage along the second fluid conduit can be permitted.
In other features, a bleed orifice can be positioned at an intersection of the first fluid conduit and the second fluid conduit. The bleed orifice can permit continuous fluid passage from the first fluid conduit to the second fluid conduit. A diameter of the bleed orifice can be between ten and twelve percent of a diameter of the first fluid conduit. The second fluid conduit can include a portion of increasing diameter extending from the bleed orifice and the intersection with the first fluid conduit. The second fluid conduit can extend vertically from the bleed orifice and the intersection with the first fluid conduit. The second fluid conduit can include a first portion extending vertically upward from the bleed orifice and the intersection with the first fluid conduit, a second portion extending horizontally from the first portion, and a third portion extending vertically downward from the second portion to the return port of the fluid reservoir.
According to additional features, the cover can include a secondary return port and a third fluid conduit. The secondary return port can be formed in the fluid reservoir spaced from the return port. The third fluid conduit can be defined within the body and extend between the first fluid conduit and the secondary return port in the fluid reservoir.
According to other features, the reservoir outlet can be positioned on the outwardly-facing surface of the body and the first outlet can be positioned on the inwardly-facing surface of the body. The first inlet can be positioned on the outwardly-facing surface of the body. The return port can be positioned internally with respect to the body, spaced from both the outwardly-facing surface and the inwardly-facing surface.
A cover assembly for a differential housing can include a body, a flange, a fluid reservoir, a first fluid conduit, a fluid pump, and a second fluid conduit. The body can have an inwardly-facing surface and an outwardly-facing surface opposite the inwardly-facing surface. The flange can extend about at least a portion of a perimeter of the body. The fluid reservoir can be defined within the body and have a reservoir outlet and a return port. The first fluid conduit can be defined within the body, spaced from the fluid reservoir, and extend between a first inlet and a first outlet. The fluid pump can have a pump inlet fluidly coupled to the reservoir outlet and a pump outlet fluidly coupled to the first inlet. The fluid pump can be mounted on the body and be operable to draw fluid from the fluid reservoir and direct the fluid into the first inlet. The second fluid conduit can be defined within the body and extend between the first fluid conduit and the return port of the fluid reservoir.
In other features, a motor can be mounted on the body and be operably positioned to power the fluid pump. A third fluid conduit can be defined within the body, spaced from the fluid reservoir, and extend from one of the first fluid conduit and the second fluid conduit to a third outlet. A fluid pressure sensor can cap the third outlet of the third fluid conduit. The third fluid conduit can extend from the first fluid conduit and be spaced from the second fluid conduit.
According to additional features, the cover assembly can include a secondary return port, a third fluid conduit, and a pressure relief valve. The secondary return port can be formed in the fluid reservoir and be spaced from the return port. The third fluid conduit can be defined within the body and extend between the first fluid conduit and the secondary return port in the fluid reservoir. The pressure relief valve can be positioned along the third fluid conduit and be proximate to the fluid reservoir.
A differential assembly can include a housing, a differential subassembly, and a cover assembly. The housing can include a first flange and can define a cavity. The differential subassembly can be positioned in the cavity of the housing. The differential subassembly can include a case, a plurality of pinion gears engaged for movement with the case, a plurality of side gears engaged with the plurality of pinion gears, a clutch pack operable to selectively interlock the case and one of the plurality of side gears, and a piston assembly positioned to act on the clutch pack and urge the clutch pack into a locking configuration. The piston assembly can include a plenum having a plenum inlet operable to receive pressurized fluid. The cover assembly can be removably engageable with the housing to selectively enclose the differential subassembly within the housing. The cover assembly can include a body having an inwardly-facing surface and outwardly-facing surface opposite the inwardly-facing surface. The cover assembly can also include a second flange extending about at least a portion of a perimeter of the body and engageable with the first flange of the housing. The cover assembly can also include a fluid reservoir defined within the body and having a reservoir outlet and a return port. The cover assembly can also include a first fluid conduit defined within the body, spaced from the fluid reservoir, and extending between a first inlet and a first outlet. The first outlet can be coupled to the plenum inlet. The cover assembly can also include a fluid pump having a pump inlet fluidly coupled to the reservoir outlet and a pump outlet fluidly coupled to the first inlet. The fluid pump can be mounted on the body and can be operable to draw fluid from the fluid reservoir and direct the fluid into the first inlet. The cover assembly can also include a second fluid conduit defined within the body and extending between the first fluid conduit and the return port of the fluid reservoir.
According to other features, the first outlet can be defined on the inwardly-facing surface of the body and the plenum can seal directly against the inwardly-facing surface. The differential assembly can also include a sealing member positioned between the inwardly-facing surface of the body and the plenum inlet. The differential assembly can also include at least one of a bleed orifice and a three-way valve positioned to limit fluid flow between the first fluid conduit and the second fluid conduit.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
A plurality of different embodiments of the disclosure is shown in the Figures of the application. Similar features are shown in the various embodiments of the disclosure. Similar features have been numbered with a common reference numeral and have been differentiated by an alphabetic suffix. Also, to enhance consistency, the structures in any particular drawing share the same alphabetic suffix even if a particular feature is shown in less than all embodiments. Similar features are structured similarly, operate similarly, and/or have the same function unless otherwise indicated by the drawings or this specification. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment or can supplement other embodiments unless otherwise indicated by the drawings or this specification.
The differential assembly 10 also includes a differential subassembly 18 positioned in the cavity 16. The differential subassembly 18 includes a case 20 enclosing a plurality of gears, described in greater detail below. The case 20 can include left-hand and right-hand portions coupled together.
The differential subassembly 18 can transmit rotary power from the vehicle engine to wheels of the vehicle. For example, rotary power is received by the differential subassembly 18 from the vehicle engine through a pinion gear 22, shown in
As set forth above, a plurality of gears are enclosed in the case 20. The differential subassembly 18 includes pinion gears 26, as shown in
The differential subassembly 18 also includes a clutch pack 34 operable to selectively interlock the case 20 and one of the plurality of side gears 30. The clutch pack 34 includes alternating metallic plates and friction material plates. Some of the plates are fixed for rotation with one of the side gears 30, while other plates are fixed for rotation with the case 20. When the clutch pack 34 is engaged, or in a locking configuration, the plates are pressed together. Further, the case 20 and the side gear 30 become fixed for rotation together. When the clutch pack 34 is disengaged, or in a released configuration, the plates are not pressed together and the case 20 and the side gear 30 are rotatable relative to each other.
The differential subassembly 18 also includes a piston assembly 36 operable to control the clutch pack 34. The piston assembly 36 is shown in
The differential assembly 10 also includes a cover assembly 44 removably engageable with the housing 12 to selectively enclose the differential subassembly 18 within the housing 12. The cover assembly 44 includes a body 46 having an inwardly-facing surface 48 and an outwardly-facing surface 50 opposite the inwardly-facing surface 48. The cover assembly 44 includes a second flange 52 extending around at least a portion of a perimeter of the body 46. The second flange 52 is engageable with the first flange 14 of the housing 12. Fasteners can pass through aligned apertures in the flanges 14, 52 to interconnect the housing 12 and the cover assembly 44.
An internal fluid circuit is formed in the body 46. As best shown in
The internal fluid circuit also includes a first fluid conduit 60 defined within the body 46. The first fluid conduit 60 is spaced from the fluid reservoir 54. The first fluid conduit 60 extends between a first inlet 62 and a first outlet 64. The first inlet 62 is positioned on the outwardly-facing surface 50 of the body 46. The first outlet 64 is positioned on the inwardly-facing surface 48 of the body 46 and is coupled to the plenum inlet 42. The exemplary first fluid conduit 60 includes a first portion 66 extending vertically upward from the first fluid inlet 62 and a second portion 68 extending horizontally from the first fluid outlet 64. The first portion 66 and the second portion 68 intersect at a position 70 along the first fluid conduit 60.
The internal fluid circuit also includes a second fluid conduit 72 defined within the body 46. The second fluid conduit 72 extends between the first fluid conduit 60 and the return port 58 of the fluid reservoir 54. The exemplary second fluid conduit 72 includes a first portion 74 extending vertically upward from the position 70. The exemplary second fluid conduit 72 also includes a second portion 76 extending horizontally from the first portion 74. The exemplary second fluid conduit 72 also includes a third portion 78 extending vertically downward from the second portion 76 to the return port 58 of the fluid reservoir 54.
As best shown in
As best shown in
A bleed orifice can be positioned at the intersection of the first fluid conduit 60 and the second fluid conduit 72, the position 70. The bleed orifice is not shown in
In one exemplary operation, the motor 86 can drive the fluid pump 80 into pumping action when engagement of the clutch pack 34 is desired. The fluid pump 80 can draw fluid from the reservoir 54 through the reservoir outlet 56 and the pump inlet 82. The fluid pump 80 can direct pressurized fluid through the pump outlet 84 and the first inlet 62. Pressurized fluid can travel through the first portion 66 of the first fluid conduit 60 to the first position 70. As will be discussed further below, some of the pressurized fluid can be diverted through the bleed orifice 88. Most of the fluid will continue along the first fluid conduit 60, reaching the second portion 68. The pressurized fluid will pass out of the first fluid outlet 64 and into the plenum 40 of the piston assembly 36. The amount of fluid in the plenum 40 will increase, causing the piston 38 to extend out of the piston assembly 36 and compress the clutch pack 34.
In another exemplary operation, the motor 86 can be disengaged, disengaging the fluid pump 80 from pumping action, when engagement of the clutch pack 34 is not desired. When this occurs, fluid can escape the plenum 40 of the piston assembly 36 and be received in the second portion 68 of the first fluid conduit 60. In some embodiments, it is possible that some fluid may pass through the first fluid conduit 60 and the fluid pump 80 to return to the reservoir. The bleed orifice 88 and the second fluid conduit 72 define a passageway for fluid evacuating the plenum 40 to return to the reservoir 54. Fluid can pass through the orifice 92, the first portion 74, the second portion 76, the third portion 78, and the return port 58 of the fluid reservoir 54.
As set forth above, pressurized fluid can be diverted from reaching the plenum 40 by passing through the bleed orifice 88 instead. However, a diameter of the bleed orifice 88 can be significantly smaller than a diameter of the first fluid conduit 60, to reduce the extent or rate of diverted fluid. In one embodiment of the present disclosure, a diameter of the orifice 92 can be ten and twelve percent of a diameter of the first fluid conduit 60. Also, the screen 96 can provide resistance to fluid movement through the bleed orifice 88.
The configuration of the second fluid conduit 72 can also provide resistance to fluid movement through the bleed orifice 88. In the exemplary embodiment, the first portion 74 of the second fluid conduit 72 extends vertically from the position 70 and the bleed orifice 88, allowing gravity to be applied to resist fluid movement. Also, the first portion 74 has a greater diameter than the bleed orifice 88 and the intersection with the first fluid conduit 60. As a depth of fluid in the first portion 74 increases, static fluid pressure against fluid movement out of the bleed orifice 88 will increase.
The exemplary cover assembly 44 also includes a third fluid conduit 98 defined within the body 46. The third fluid conduit 98 can be spaced from the fluid reservoir 54 and extend from the first fluid conduit 60 or the second fluid conduit 72 to a third outlet. In the exemplary embodiment, the third fluid conduit 98 extends from the first fluid conduit 60 and is spaced from the second fluid conduit 72. A fluid pressure sensor 118 can cap the third outlet of the third fluid conduit 98. Data sensed by the pressure sensor 118 can be applied by a controller (not shown) to control the operation of the motor 86.
A second embodiment of the present disclosure is shown in
The differential assembly also includes a cover assembly 44a removably engageable with the housing 12a to selectively enclose the differential subassembly within the housing 12a. The cover assembly 44a includes a body 46a having an inwardly-facing surface (not visible) and outwardly-facing surface 50a opposite the inwardly-facing surface. An internal fluid circuit is formed in the body 46a. The exemplary cover assembly 44a can also include a fluid pump 80a and a motor 86a operably positioned to power the fluid pump 80a for pumping fluid through the fluid circuit.
As best shown in
The internal fluid circuit also includes a second fluid conduit 72a defined within the body 46a. The second fluid conduit 72a extends between the first fluid conduit 60a and the return port 58a of the fluid reservoir 54a. The exemplary second fluid conduit 72a includes a first portion 74a extending vertically upward and a second portion 76a extending horizontally from the first portion 74a to the return port 58a.
A three-way valve can be located at a position 70a, the point of intersection between the first and second fluid conduits 60a, 72a. The three-way valve limits fluid flow between the first and second fluid conduits 60a, 72a and is illustrated schematically at 110a. The three-way valve 110a is operable in a first setting and a second setting. In the first setting, the three-way valve 110a permits fluid passage between the first inlet 62a and the first outlet 64a. Fluid passage along the second fluid conduit 72a is prevented. The three-way valve 110a is configured in the first setting when fluid is being pumped to the clutch of the differential assembly. In the second setting, the three-way valve 110a prevents fluid passage between the first inlet 62a and the first outlet 64a. Fluid is diverted off the first fluid conduit 60a at the position 70a and diverted to the second fluid conduit 72a. The three-way valve 110a is configured in the second setting when the clutch is de-energized and fluid is flowing back to the reservoir 54a.
The second exemplary embodiment includes the secondary return port 100a formed in the fluid reservoir 54a spaced from the return port 58a. A third fluid conduit 112a is defined within the body 46a and extends between the first fluid conduit 60a and the secondary return port 100a of the fluid reservoir 54a. A pressure relief valve 114a can be positioned along the third fluid conduit 112a proximate to the fluid reservoir 54a. The pressure relief valve 114a can open in response to excessive pressure in the first fluid conduit 60a.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
This application is a continuation of International Patent Application No. PCT/US2014/040494 filed on Jun. 2, 2014, which claims the benefit of U.S. Patent Application No. 61/831,584 filed on Jun. 5, 2013 and U.S. Patent Application No. 62/006,321 filed on Jun. 2, 2014. The disclosures of the above applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61831584 | Jun 2013 | US | |
| 62006321 | Jun 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2014/040494 | Jun 2014 | US |
| Child | 14957944 | US |
