Drive assembly - Patent Review 4181042

What is claimed is:

1. A drive assembly for use in driving a driven member, said drive assembly comprising a casing, a planetary gear assembly disposed within said casing, said planetary gear assembly including a sun gear, a ring gear, a planet carrier, and a planet gear on said planet carrier connected with said sun and ring gears, input means for effecting rotation of at least one of said gears, output means connected with said planetary gear assembly for effecting rotation of the driven member, said output means including a first section connected with said planet carrier and a second section to be connected with the driven member for rotation therewith, brake means operable from an engaged condition to a disengaged condition, said brake means being effective in the engaged condition to hold said first output section and said one gear against rotation relative to said casing, said brake means being effective in the disengaged condition to enable said first output section and said one gear to be rotated relative to said casing, and clutch means operable between an engaged condition interconnecting said first and second output sections and a disengaged condition enabling said second output section to be rotated relative to said first output section and said casing when said brake means is in said engaged condition, said clutch means including a clutch member encircling said second section and movable between a first position engaging said first and second output sections and a second position spaced from one of said output sections, spring means for urging said clutch member toward said first position and retaining means for retaining said clutch member in said second position against the influence of said spring means, said retaining means comprising a rod having a threaded connection with said clutch member and which upon rotation thereof in one direction effects movement of said clutch member to said second position due to said threaded connection and retains said clutch member thereat.

2. A drive assembly as defined in claim 1 wherein said clutch member comprises an annular gear member having internal splines for engaging external splines on said second section and external splines for engaging internal splines on said first section.

3. A drive assembly as defined in claim 2 wherein said clutch member further includes a plate secured to said annular gear member, said plate and said rod having said threaded connection, and said rod extends through a passage in said second section and is rotatable relative thereto.

4. A drive assembly for driving a driven member, said drive assembly comprising a casing, a planetary gear assembly disposed within said casing, said planetary gear assembly comprising a sun gear, a planet carrier, a planet gear rotatably mounted on said planet carrier and connected with said sun gear, and a rotatable annular ring gear disposed in meshing engagement with said planet gear, input means for effecting rotation of at least one of said gears, output means connected with said planet carrier for effecting rotation of the driven member, a first annular section connected to said ring gear for rotation therewith and extending axially outwardly from a first side of said ring gear, a second annular section connected to said ring gear for rotation therewith and extending axially outwardly from a second side of said ring gear, said first and second annular sections being coaxial and having the same inside diameters, a first annular disc pack circumscribed by said first annular section and connected with said planet carrier and said first annular section, a second annular disc pack circumscribed by said second annular section and connected with said casing and said second annular section, means for actuating said first disc pack to retard relative rotation between said first annular section and said planet carrier, and means for actuating said second disc pack to retard relative rotation between said second section and said casing.

5. An assembly as set forth in claim 4 further including a first set of teeth disposed in an annular array on the inside of said first annular section and disposed in engagement with said first annular disc pack, a second set of teeth disposed in an annular array on the inside of said second annular section and disposed in engagement with said second annular disc pack, and said first and second sets of teeth being located equal distances from the axis of said ring gear, and said first and second disc packs comprise means supporting said ring gear for axial and rotational movement unimpeded by bearings and said ring gear is free to move axially relative to said planet gear.

6. An assembly as defined in claim 5 wherein said first and second annular sections are integrally formed with said ring gear.

7. An assembly as set forth in claim 6 wherein said output means includes a first output section of said planet carrier adapted to be rotated by said planetary gear assembly and a second output section adapted to be connected with the driven member for rotation therewith, clutch means operable between an engaged condition interconnecting said first and second output sections to enable rotational drive forces to be transmitted therebetween and a disengaged condition enabling said second output section to be rotated relative to said first output section and said casing.

8. An assembly as set forth in claim 7 wherein said clutch means includes a clutch member encircling said second section and movable between a first position engaging said first and second output sections and a second position spaced from one of said output sections, spring means for urging said clutch member toward said first position and retaining means for retaining said clutch member in said second position against the influence of said spring means, said retaining means comprising a rod having a threaded connection with said clutch member and which upon rotation thereof in one direction effects movement of said clutch member to said second position due to said threaded connection and retains said clutch member thereat.

9. An assembly as set forth in claim 4 wherein said means for actuating said first disc pack includes a first annular disc spring member disposed adjacent to and axially outwardly of an end portion of said first annular section, said first annular disc spring member having an outside diameter which is greater than the outside diameters of said first annular section and said ring gear and an inside diameter which is less than the inside diameters of said first annular section and said ring gear, said means for actuating said second disc pack including a second annular disc spring member disposed adjacent to and axially outwardly of an end portion of said second annular section, said second annular disc spring member having an outside diameter which is greater than the outside diameters of said second annular section and said ring gear and an inside diameter which is less than the inside diameters of said second annular section and said ring gear.

10. A drive assembly for use in driving a driven member, said drive assembly comprising a casing, a planetary gear assembly in said casing, said planetary gear assembly comprising a rotatable sun gear, a rotatable ring gear, a rotatable planet gear connected with said sun and ring gears, and a planet carrier supporting said planet gear for movement relative to said ring gear about the axis of rotation of said sun gear, input means for effecting rotation of at least one of said gears, output means connected with said planetary gear assembly for effecting rotation of the driven member, clutch means operable between an engaged condition holding said planet carrier and ring gear against movement relative to each other and a disengaged condition in which said clutch means is ineffective to hold said planet carrier and ring gear against movement relative to each other, said clutch means being rotatable relative to said casing about the axis of rotation of said sun gear with said planet carrier and ring gear when said clutch means is in said engaged condition, and a disc spring operable between an active condition urging said clutch means to the engaged condition and an inactive condition in which said disc spring is ineffective to urge said clutch means to the engaged condition, said disc spring being spaced from said casing and acting between a first bearing surface area on said planet carrier and a second bearing surface area on said clutch means when said disc spring is in the active condition to enable said disc spring to rotate relative to said casing with said planet carrier and clutch means, said disc spring being spaced from said planet carrier and clutch means and acting against a third bearing surface area on said casing when said disc spring is in the inactive condition to enable said planet carrier and first clutch means to rotate relative to said disc spring when said disc spring is in the inactive condition, and means for moving said disc spring between its active and inactive conditions.

11. An assembly as set forth in claim 10 wherein said spring has a natural resilience which urges it from the inactive condition toward the active condition, said means for moving said spring includes a fluid motor means connected with said casing, and said second bearing surface on said clutch means comprising a continuous annular bearing surface encircling the axis of rotation of said ring gear.

12. An assembly as set forth in claim 11 wherein said fluid motor means effects pivotal movement of said spring away from said first bearing surface area about said third bearing surface area upon initiation of movement of said spring from said active condition toward said inactive condition.

13. An assembly as set forth in claim 11 wherein said spring includes an annular member having a pair of opposite side surface areas interconnecting a circular inner rim portion and a circular outer rim portion, said inner rim portion being disposed in engagement with said first bearing surface area and one of said side surface areas being disposed in engagement with said second bearing surface area when said spring is in the active condition, said inner rim portion and one side surface area of said spring being spaced from said first and second bearing surface areas and the side surface area opposite from said one side surface area being disposed in engagement with said third bearing surface area when said spring is in said inactive condition.

14. An assembly as set forth in claim 13 wherein said fluid motor includes means for applying a force to said circular outer rim portion of said spring to effect operation of said spring from the active condition to the inactive condition.

15. An assembly comprising a casing, first and second rotatable members in said casing, a clutch having engaged and disengaged conditions interposed between said first and second members, a disc spring encircling the axis of rotation of one of said members and biasing said clutch to said engaged condition and having an active condition when said clutch is engaged and an inactive condition when it is disengaged, means for causing said disc spring to rotate with said first rotatable member when said disc spring is in its active condition, and means for preventing rotation of said disc spring with said first or second member when said disc spring is in its inactive condition, said means for causing said disc spring to rotate comprising a first bearing surface area connected with said first rotatable member when said disc spring is in the active condition and against which said disc spring acts, and said means for preventing rotation of said disc spring comprising means for moving said disc spring to its inactive condition away from said first bearing surface area and into engagement with a second bearing surface area on said casing, thereby enabling said first bearing surface area to rotate relative to said disc spring when said disc spring is in the inactive condition, said clutch including a clutch member rotatable with said first rotatable member, said disc spring acting against a third bearing surface area on said clutch member and said first bearing surface area when said disc spring is in said active condition to enable said disc spring to rotate relative to said casing with said first rotatable member and clutch member, said third bearing surface area being a continuous annular area encircling the axis of rotation of the second rotatable member, said disc spring having an annular configuration with circular inner and outer edge portions interconnected by opposite side surfaces, said circular inner and outer edge portions being movable axially relative to each other to resiliently flex said disc spring between said active and inactive conditions, said first bearing surface area being disposed in engagement with one of said side surface areas when said disc spring is in the active condition, and said third bearing surface area being disposed in engagement with the second side surface area opposite from said one side surface area when said disc spring is in said active condition.

16. An assembly as defined in claim 15 wherein said second bearing surface area on said casing engages said one side surface area at a location spaced from where said first bearing surface area engages said one side surface area, and said second bearing surface area comprising means for pivoting said disc spring away from said first bearing surface area upon actuation of said means for moving said disc spring to its inactive condition.

17. A drive assembly for use in driving a driven member, said drive assembly comprising a casing, a planetary gear assembly including a ring gear and a planet carrier rotatably supported in said casing, a clutch having engaged and disengaged conditions interposed between said ring gear and planet carrier, a disc spring encircling the axis of rotation of said planet carrier and biasing said clutch to said engaged condition and having an active condition when said clutch is engaged and in an inactive condition when it is disengaged, means for causing said disc spring to rotate with said planet carrier when said disc spring is in its active condition, and means for preventing rotation of said disc spring with said ring gear or said planet carrier when said disc spring is in its inactive condition, said means for causing said disc spring to rotate comprising a first bearing surface area connected with said planet carrier when said disc spring is in the active condition and against which said disc spring acts, and said means for preventing rotation of said disc spring comprises means for moving said disc spring to its inactive condition away from said first bearing surface area and into engagement with a second bearing surface area on said casing, thereby enabling said first bearing surface area to rotate relative to said disc spring when said disc spring is in the active condition.

18. A drive assembly as set forth in claim 17 wherein said clutch includes a clutch member rotatable with said ring gear, and said disc spring acting against a bearing surface area on said clutch member and said first bearing surface on said planet carrier when said disc spring is in said active condition to enable said disc spring to rotate relative to said casing with planet carrier and clutch member, said bearing surface area on said clutch member being a continuously annular area encircling the axis of rotation of the ring gear.

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BACKGROUND OF THE INVENTION

This invention relates to a new and improved drive assembly and more specifically to a drive assembly in which planetary gears are utilized to transmit drive forces between input and output members. A clutch and brake arrangement is advantageously associated with the planetary gears to effect a change in the speed of rotation of the output member relative to the speed of rotation of the input member.

Planetary gear assemblies have previously been utilized in association with various clutch and brake arrangements to effect a variation in the speed of rotation of an output member relative to an input member. Certain known transmissions having clutches in association with planetary gear assemblies are disclosed in U.S. Pat. Nos. 2,293,050; 2,373,122; 2,870,655; 3,296,893; 3,308,686; 3,319,492 and in Italian Pat. No. 957,342. Various planetary gear assemblies have also been utilized to drive the wheels of a vehicle in the manner disclosed in U.S. Pat. Nos. 2,893,268; 3,217,826; 3,653,454; 3,686,978 and 3,969,950. In addition to the wheel drive arrangements disclosed in the aforementioned patents, it has been suggested that clutches could be provided in association with the planetary gear assembly to effect a variation in the speed of rotation of an output member relative to the speed of rotation of an input member.

When a planetary gear assembly is utilized to drive the wheels of a vehicle, it is advantageous to provide a clutch in the output from the gear assembly to enable the vehicle to be towed without actuating the planetary gear assembly. Such an arrangement is disclosed in the aforementioned U.S. Pat. Nos. 3,686,978 and 3,969,950.

SUMMARY OF THE PRESENT INVENTION

The present invention provides a new and improved drive assembly which includes a plantary gear assembly and a clutch and a brake to effect a variation in the speed of rotation of an output member relative to the speed of rotation of an input member. The clutch and brake are actuated from an engaged condition to a disengaged condition under the influence of fluid pressure. If both of the clutch and brake are in the engaged condition, the brake assembly is locked in such a manner that the output member can not rotate. In order to enable the output member to be rotated when a pump or other source of fluid for actuating the clutch and brake is ineffective to supply fluid under pressure, a secondary or towing clutch is provided in association with the output from the drive assembly. By releasing the secondary clutch, the output member can be freely rotated.

In accordance with another feature of the present invention, wear between various parts of the drive assembly is minimized. To accomplish this, springs for effecting actuation of the clutches associated with the planetary gear assembly are associated with parts of the drive assembly so that minimum relative rotation of the springs and parts occurs which could result in wear.

The ring gear of the planetary gear assembly is free to shift axially relative to the planet gears to thereby distribute the ring gear tooth wear caused by the planet gear teeth over a relatively large area of the ring gear teeth. The freedom of the ring gear to shift axially is obtained by eliminating relatively bulky and expensive bearing arrangements which have been previously utilized to support the ring gear for rotation and to hold the ring gear against axial movement relative to the planet gears. The compact construction of the drive assembly is further promoted by providing a relatively simple interconnection between the ring gear and a pair of disc packs which are utilized to retard relative rotation between the ring gear and either the planet carrier or the casing of the drive assembly. This simple interconnection is obtained by forming the ring gear with a pair of side sections having teeth or splines which engage discs. The teeth or splines on the two side sections have the same diameter to facilitate the forming of the ring gear and side sections.

Accordingly, it is an object of this invention to provide a new and improved drive assembly having a speed control arrangement associated with planetary gearing, the speed control arrangement being actuatable from an engaged condition locking on output member and the planetary gearing against rotation and wherein a towing clutch is disengageable to release the output member in the event that fluid pressure is unavailable to effect actuation of the speed control arrangement to the disengaged condition.

Another object of this invention is to provide a new and improved drive assembly having a disc pack assembly in association with a planetary transmission and wherein a spring for operating the disc pack assembly is maintained free of frictional engagement with relatively moving surfaces when the disc pack assembly is in either an engaged condition or a disengaged condition.

Another object of this invention is to provide a new and improved drive assembly having a planetary gear arrangement in which a ring gear has a pair of side sections of the same diameter, the ring gear side sections being connected with a pair of disc packs which are selectively engageable.

Another object of this invention is to provide a new and improved drive assembly having a planetary gear arrangement in which a ring gear is supported for combined rotational and axial movement relative to a casing and in which axial movement of the ring gear is unimpeded by bearings.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and features of the present invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a partially broken away sectional view of a drive assembly constructed in accordance with the present invention;

FIG. 2 is an enlarged fragmentary sectional view of a portion of the drive assembly of FIG. 1;

FIG. 3 is a view taken generally along the line 3--3 of FIG. 1 and further illustrating the construction of the drive assembly;

FIG. 4 is a view, taken generally along the line 4--4 of FIG. 1 illustrating the manner in which a driven member, such as a wheel, is connected with the drive assembly;

FIG. 5 is an enlarged fragmentary view illustrating the manner in which a clutch actuating spring is moved out of engagement with bearing surfaces which rotate relative to each other when the clutch is disengaged;

FIG. 6 is a fragmentary sectional view illustrating the manner in which a secondary or towing clutch is actuated to an intermediate condition in which teeth on a pair of clutch members are misaligned; and

FIG. 7 is a fragmentary sectional view, generally similar to FIG. 6, illustrating the clutch members of FIG. 6 in an engaged condition after the teeth on the clutch member have moved into alignment.

DESCRIPTION OF ONE SPECIFIC PREFERRED EMBODIMENT OF THE INVENTION

General Construction of Drive Assembly

A drive assembly 10 constructed in accordance with the present invention is illustrated in FIG. 1 and includes a hydraulic motor 12 which is utilized to drive an output member 14 through a planetary transmission or gear assembly 16. Although the output member 14 is connected with the rim 18 of a vehicle wheel, it is contemplated that the output member 14 could be connected with other driven members in environments other than in association with a vehicle. A primary or speed control arrangement 22 is utilized in association with the planetary gear assembly 16 to vary the rate of rotation with the output member 14 relative to the rate of rotation of an input member 24 connected with a motor output or wobble shaft 26. A secondary or towing clutch assembly 30 is provided to enable the output member 14 to be selectively disconnected from the planetary gear assembly 16.

The speed control arrangement 22 includes a pair of coaxial disc assemblies 34 and 36 which are capable of being independently engaged and disengaged to effect operation of the drive assembly 10 in any one of four modes. Disc assembly 34 is referred to herein also as a clutch assembly and disc assembly 36 is also referred to herein as a brake assembly. When both of the disc assemblies 34 and 36 are engaged, the planetary gear assembly 16 is locked up and the output member 14 is held against rotation as long as the secondary or towing clutch 30 is engaged (FIG. 7). Upon disengagement of the clutch assembly 34 (FIG. 1) with the brake assembly 36 engaged, the output member 14 is rotated at a low speed relative to the speed of rotation of the input member 24. Upon disengagement of the brake assembly 36 with the clutch assembly 34 engaged, the output member 14 is rotated at the same rate as the input member 24. Finally, if both of the disc assemblies 34 and 36 are disengaged, a neutral condition exists in which the output member 14 is freely rotatable relative to the input member 24 and the input member is ineffective to drive the output member.

The disc assemblies 34 and 36 (FIG. 1) are actuated to their engaged conditions by a pair of belleville type springs 40 and 42. To disengage the disc assemblies 34 and 36, a pair of fluid motors 44 and 46 are operated under the influence of fluid pressure transmitted from a pump 48 through a valve assembly 50. Operation of the fluid motors 44 and 46 deflects the springs 40 and 42 outwardly away from the associated disc packs 34 and 36. This results in disengagement of the disc packs. It should be noted that in the event that the pump 48 is ineffective to supply fluid under pressure to the motors 44 and 46 due to either a shutting down of a motor for driving the pump or due to a malfunctioning of the pump, the springs 40 and 42 will automatically cause the disc packs 34 and 36 to become engaged to lock up the planetary transmission 16 and hold the output member 14 against rotation when the clutch assembly 30 is engaged.

Secondary or Towing Clutch

It is contemplated that under certain circumstances it may be desirable to allow the output member 14 to be rotated when the pump 48 is ineffective to supply fluid pressure to the motors 44 and 46 to effect disengagement of the disc assemblies 34 and 36. For example, this situation could occur when a vehicle with which the wheel drive assembly 10 is associated is being towed or when there has been a malfunctioning of either the pump 48 or its drive motor. To enable the wheel connected with the output member 14 to be rotated when both of the disc assemblies 34 and 36 are engaged, the secondary or towing clutch 30 is actuated from the engaged condition as shown in FIG. 7 to the disengaged condition shown in FIG. 1.

When the secondary clutch 30 is in the engaged condition shown in FIG. 7, an annular array of teeth 54 on the outside of a cylindrical clutch member 56 are disposed in meshing engagement with an annular array of teeth 58 formed on the inside of a cylindrical transmission output member 62 which is connected directly with the planetary gear assembly 16 (see FIG. 2). When the clutch member 56 is in the engaged position illustrated in FIG. 7, drive forces are transmitted from the transmission output member 62 through the clutch member to the output member 14. To provide for the transmission of force between the clutch member 56 and the output member 14, an annular array of teeth 66 formed on the inside of the clutch member 56 are disposed in meshing engagement with an annular array of teeth 68 formed on the outside of a cylindrical end portion 70 of the output member 14. Therefore, upon rotation of the transmission output member 62 by the planetary gear assembly 16 with the clutch member 56 in the engaged condition, the output member 14 is rotated at the same speed as the transmission output member 62.

To effect axial movement of the clutch member 56 from the engaged position of FIG. 7 to the disengaged position of FIGS. 1 and 2, a manually engageable clutch actuator knob 74 (FIGS. 1 and 4) is rotated. Rotation of the actuator knob 74 causes screw threads 78 (FIG. 2) formed on an inner end of an actuator shaft 80 to move an internally threaded circular end wall 90, toward the left from the position shown in FIG. 7 to the position shown in FIG. 2. The end wall 90 is fixedly connected to the clutch member 56. Therefore, leftward movement of the end wall 90 moves the clutch member 56 from the engaged position shown in FIG. 7 to the disengaged position shown in FIG. 2.

When the clutch member 56 is in the disengaged position shown in FIG. 2, the external teeth 54 on the clutch member are spaced apart from the internal teeth 58 on the transmission output member 62. Therefore, the planetary gear assembly 16 is ineffective to drive the output member 14 and the output member 14 can be freely rotated relative to a casing 94 which encloses the planetary gear assembly 16. Of course, this enables the output member 14 to be rotated when the disc assemblies 34 and 36 are held in the engaged condition locking the transmission output member 62 against rotation.

When the secondary clutch 30 is to be operated from the disengaged condition of FIG. 2 back to the engaged condition of FIG. 7 to provide for the transmission of drive forces from the planetary gear assembly 16 to the output member 14, it is necessary to move the teeth 54 on the clutch member 56 into meshing engagement with the teeth 58 on the transmission output member 62 in the manner shown in FIG. 7. To accomplish this, the clutch actuator shaft 80 is rotated to cause the threads 78 on the end of the shaft to move the end wall 90 toward the right (as viewed in FIG. 2). If the external teeth 54 on the clutch member 56 are exactly aligned with spaces between the internal teeth 58 on the transmission output member 62, continued rotation of the clutch actuator shaft 80 causes the clutch member 56 to be moved from the disengaged position of FIG. 2 to the engaged position of FIG. 7. However in all probability, the teeth 54 on the clutch member 56 will not be aligned with the teeth 58 on the transmission output member 52. Due to the misalignment of the two sets of teeth 54 and 58, the leading ends 98 of the teeth 54 move into abutting engagement with the outer ends 100 of the teeth 58 in the manner illustrated in FIG. 6. Due to this abutting engagement between the two annular arrays of teeth 54 and 58, continued rotation of the clutch actuator shaft 80 will merely cause the actuator shat to project outwardly from the output member 14 in the manner illustrated in FIG. 6.

When the clutch member 56 is in the intermediate position of FIG. 6, operation of the motor 12 or rotation of the wheel rim 18 will cause relative rotation between the output member 14 and the transmission output member 62. This relative rotation enables the two sets of teeth 54 and 58 to move into alignment. Once the teeth 54 and 58 have moved into alignment, a coil spring 104 will cause the clutch member 56 to snap inwardly, to the engaged position of FIG. 7. The coil spring 104 is disposed between an end wall 106 of a cylindrical cavity in the end portion 70 of the output member 14 and the end wall 90 connected with the clutch member 56. Thus, the secondary clutch 30 is selectively operable between an engaged condition (FIG. 7) in which the output member 14 and wheel rim 18 are held against rotation relative to the transmission output member 62 and a disengaged condition (FIG. 1) in which the output member 14 and wheel rim 18 are freely rotatable relative to the transmission output member 62 to enable the wheel rim 18 to be rotated when the disc assemblies 34 and 36 are both engaged during towing of the vehicle or other operating conditions.

Actuator Springs

In accordance with another one of the features of the present invention, wear of the actuator springs 40 and 42 is minimized during operation of the drive assembly 10 by minimizing frictional drag on the springs. The annular spring 40 is resiliently deflectable between the active condition of FIG. 2 in which it is effective to cause engagement of the clutch assembly 34 and the inactive condition of FIG. 5 in which it is ineffective to cause engagement of the clutch assembly 34.

When the spring 40 is in the active condition illustrated in FIG. 2, the clutch assembly 34 is engaged so that the ring gear 108 and planet carrier 110 of the planetary gear assembly 16 are rotated at the same speed. A plurality of planet gears 112 are rotatably mounted on the planet carrier 110. Each of the planet gears 112 is rotatably supported by an axle shaft 114 extending between an annular base wall 116 and a support arm 118. Since the clutch 34 is engaged and the ring gear 108 and planet carrier 110 are interconnected, the planet gears 112 are held against rotation about the axle 114 by their meshing engagement with the ring gear 108. If a sun gear 122 is rotated by the input member 24 with the clutch assembly 34 eng