Pump drive system

FIELD OF THE INVENTION

The present invention relates generally to a drive system and more particularly to a pump drive and support structure.

BACKGROUND OF THE INVENTION

Wet clutch assemblies, which are clutches that use oil to cool and lubricate the clutch plates, are known in the art. Wet clutches are commonly positioned between an input device, such as an engine, and an output device, such as a transmission to engage/disengage the output device from the input device. Wet clutches are generally pressure engaged and spring disengaged for high horsepower applications or spring engaged and pressure disengaged for lower horsepower applications.

Gerotor pumps are commonly used with wet clutches to supply the hydraulic fluid needed for cooling, lubrication and pressure engagement/disengagement of the clutch. Gerotor pumps typically include internally toothed and externally toothed gear members rotatably disposed within a pump housing. The gear members are generally coupled to the input device in such a way as to rotate in proportion to the speed of the input device. A first gear member, or pinion gear, typically rotates on a longitudinal centerline common to the centerline of the clutch and pump itself. A second gear member, or ring gear, typically rotates on a longitudinal centerline parallel, but laterally separated from the centerline of the pinion gear. In this manner, the teeth on the respective gear members cooperate to define a plurality of variable volume pumping chambers. During rotation of the gear members, a pumping chamber increases in volume to a maximum volume and then decreases in volume. Fluid from the inlet port of the pump is drawn into the pumping chambers that are increasing in volume. Upon further rotation of the gerotor when the pumping chambers are decreasing in volume, the fluid is pushed out through the outlet port of the pump at a higher pressure.

In a conventional design, a gerotor pump is connected to the clutch assembly such that the rotation of a clutch input member provides rotational power to drive the pump. In this particular configuration, the pump is concentrically aligned in direct rotative connection with the wet clutch assembly. The connection is typically accomplished via the engagement of mating splined surfaces located on a clutch armature and the first gear member of the pump. In this manner, the pump is operational upon activation of the input device to immediately supply hydraulic fluid to the clutch. During operation of the pump, radial loads are generated by the high fluid pressures created as the volume of the pumping chambers is decreased. The direct splined connection between the clutch armature and pinion gear of the pump induces moment loads on the pinion gear of the pump and limits the ability of the mating components to counteract the radial loads, resulting in premature wear or possible damage to the pumping elements and mating components. The present invention provides an effective pump drive and support device that transfers rotative power between a clutch and a pump without premature wear or possible damage to the pumping elements or mating components.

SUMMARY OF THE INVENTION

The present invention provides an innovative drive system that couples a clutch assembly with a pump assembly to provide power to control operation of a clutch.

In accordance with an embodiment of the present invention, a drive system is disclosed that includes a drive coupling rotatably supported on an input shaft. The drive coupling includes a generally cylindrical body having a duct therethrough for receiving the input shaft. A bearing member is disposed in a groove on each end of the drive coupling between the body of the coupling and the input shaft to permit independent rotation of the drive coupling on the input shaft. A thrust washer is disposed on each end of the drive coupling proximate the bearing members to secure the bearing members in each groove. A locking member is preferably provided on both a forward end and a rearward end of the drive coupling proximate the thrust washers to secure the position of the drive coupling on the input shaft. The drive coupling further includes at least two connecting surfaces proximate each end of the body that engage a corresponding connecting inner surface of both an armature of thr clutch assembly and a pinion gear of the pump assembly. Upon activation of an input device, and provided the clutch is “disengaged”, the drive coupling will rotate with the clutch assembly independent of the idle input shaft. The rotation of the drive coupling causes a pinion gear of the pump that is positioned concentric to the input shaft to rotate at a speed proportional to the speed of a clutch armature, thereby permitting operation of the pump. Operation of the pump provides fluid power to cool, lubricate and control operation of the clutch.

The foregoing drive system limits moment loads generated at the connecting surfaces and counteracts radial loads generated by the pumping elements to prevent premature wear or possible damage to the pumping elements and mating components. Moreover, the drive system permits differential rotation between the drive coupling and input shaft. Various additional aspects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description:

FIG. 1

is an exploded perspective view of an embodiment of the present invention showing a drive coupling and an input shaft assembly.

FIG. 2

is a sectioned view showing the drive coupling in splined engagement with a clutch armature and a pump assembly.

FIG. 3

is a perspective view showing the drive coupling assembled on the input shaft.

FIG. 4

is a sectioned view of the drive coupling and input shaft along the line

4

—

4

in FIG.

3

.

FIG. 5

is a sectioned view along the line

5

—

5

in FIG.

2

.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, the preferred embodiments of the present invention are described in detail. Referring to

FIGS. 1 and 2

, a preferred embodiment of the present invention is shown that includes a drive coupling

10

rotatably supported on an input shaft

12

for transferring rotational power between a clutch assembly

14

and a pump assembly

16

. Clutch assembly

14

generally includes an input member

15

and an output member

17

that rotate together when the clutch is “engaged” and independent of each other when the clutch is “disengaged.” Generally, clutch assembly

14

is “engaged” when a plurality of plates attached to both input member

15

and output member

17

are forced into frictional contact, such that the plates rotate at substantially the same speed. Clutch input member

15

is generally coupled to an input device (not illustrated), such as an engine, in such a way as to rotate in proportion to the speed of the input device. Input shaft

12

is connected to output member

17

such that input shaft

12

rotates at a speed proportional to that of the input device when the clutch is “engaged.” Input shaft

12

generally provides rotational input to a power-transmitting device (not illustrated), such as a transmission.

Referring to

FIGS. 1

,

3

and

4

, drive coupling

10

preferably includes a generally cylindrical body

18

having a duct

20

therethrough for receiving input shaft

12

. A plurality of bearing members

22

and

24

, such as a needle bearing, are preferably disposed in at least two grooves

26

,

28

positioned at a forward end

30

and a rearward end

32

of drive coupling

10

respectively. Bearing members

22

,

24

are positioned between body

18

and an external surface

33

of input shaft

12

to permit independent rotation of drive coupling

10

on input shaft

12

. A thrust washer

34

is preferably disposed proximate each end

30

,

32

of drive coupling

10

to secure the position of bearing members

22

,

24

in grooves

26

,

28

respectively. Surface

33

preferably includes one, and more preferably two grooves

36

for receiving a locking member

37

, such as a snap ring. Locking member

37

is preferably positioned proximate thrust washers

34

to secure the position of drive coupling

10

on input shaft

12

. Drive coupling

10

further includes two connecting surfaces

40

,

42

that are preferably splined and more preferably positioned proximate each end

30

,

32

, respectively. Referring to

FIG. 2

, upon assembly of input shaft

12

into pump assembly

16

and clutch assembly

14

, connecting surface

40

is positioned to engage a corresponding connecting inner surface

44

of a clutch armature

46

. Similarly, connecting surface

42

is positioned to engage a corresponding connecting inner surface

48

of a pinion gear

50

located within pump assembly

16

. Clutch armature

46

is secured to clutch input member

15

such that clutch armature

46

rotates at a speed proportional to the input device.

Referring to

FIGS. 2 and 5

, pump assembly

16

is preferably positioned concentric to input shaft

12

along a first longitudinal centerline

51

and generally includes a pump

52

and a manifold

54

. Pump

52

, preferably of the gerotor type, generally includes a ring gear

56

having a cylindrical outside surface

58

that cooperates with a cylindrical inside surface

60

of a housing

62

in supporting the ring gear

56

for rotation about a second longitudinal centerline

64

parallel to and laterally separated from first longitudinal centerline

51

of pump assembly

16

. Pinion gear

50

is disposed inside of ring gear

56

and coupled to drive coupling

10

for rotation as a unit with drive coupling

10

about first longitudinal centerline

51

of pump assembly

16

. The lateral separation between longitudinal centerlines

51

and

64

and the teeth

65

on the respective gears

50

and

56

cooperate to define a plurality of variable volume pumping chambers

66

, whereupon during rotation of the gear members, a pumping chamber

66

increases in volume to a maximum volume, then decreases in volume. Fluid from an inlet port (not illustrated) in pump assembly

16

is drawn into pumping chambers

66

that are increasing in volume. Upon further rotation of gears

50

and

56

, pumping chambers

66

decrease in volume to push the fluid out through the pump's outlet port (not illustrated) at a higher pressure. Operation of pump assembly

16

provides fluid power to cool, lubricate and control the operation of clutch assembly

14

.

Operation of drive coupling

10

will now be described with reference to

FIGS. 2 and 5

. Upon activation of the input device, drive coupling

10

begins to rotate at a speed proportional to the rotation of clutch armature

46

. The rotation of drive coupling

10

causes pinion gear

50

in pump

52

to rotate at a speed proportional to the speed of clutch armature

46

to permit operation of pump assembly

16

as described above. During rotation of pinion gear

50

and ring gear

56

, radial loads are generated as the fluid is compressed in pumping chambers

66

that are decreasing in volume. The effect of the radial loads produced by the compressed fluid can be characterized as a force that attempts to push pinion gear

50

and connected drive coupling

10

off center. Additionally, the connecting surfaces between drive coupling

10

and clutch armature

46

create a moment load on drive coupling

10

. However, by rotatably supporting drive coupling

10

on input shaft

12

, the radial and moment loads acting on drive coupling

10

are counteracted to prevent premature wear or possible damage to the components.

As described above, input shaft

12

remains idle when the clutch is “disengaged.” Bearing members

22

,

24

permit drive coupling

10

to rotate with clutch armature

46

independent of the idle input shaft

12

. The independent rotation capability of drive coupling

10

on input shaft

12

permits different rotation speeds of the input shaft

12

and drive coupling

10

as the clutch is gradually engaged. As the clutch is engaged, the input shaft increases in speed until the speed of input shaft

12

is substantially proportional to the speed of drive coupling

10

.

Accordingly, the present invention provides a pump drive and support restructure that permits concentric alignment of a pump assembly with an input shaft and clutch assembly. The inventive pump drive and support structure counteracts the radial and moment loads generated by the pump elements during operation of the pump to prevent premature wear or damage to the components. Additionally, the inventive pump drive and support structure allows differential rotation between the input shaft and the drive coupling.

Although certain preferred embodiments of the present invention have been described, the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention. A person of ordinary skill in the art will realize that certain modifications and variations will come within the teachings of this invention and that such variations and modifications are within its spirit and the scope as defined by the claims.