JP4556911B2 - Planetary gear type automatic transmission - Google Patents

Description

  The present invention relates to a piston that presses a friction engagement element in a planetary gear type automatic transmission including a friction engagement element such as a clutch and a brake.

In an automatic transmission that achieves automatic transmission by engaging and releasing a brake and a clutch having a friction engagement element composed of a plurality of friction plates, a first cylinder that constitutes a cylindrical portion as a piston that presses the friction engagement element A piston member and a two-member piston member constituting the bottom part are known (for example, Patent Document 1). In the piston described in Patent Document 1, a claw-like portion formed in the second piston member (bottom portion) is fitted into a notch formed in the first piston member (cylindrical portion), and both members are formed by a snap ring. Are connected together.
JP-A-9-32919

  Thus, when the piston is constituted by two members, the first piston member constituting the cylindrical portion and the second piston member constituting the bottom portion, and both members are integrally connected by a snap ring or the like, both members are respectively Since it is manufactured within a predetermined dimensional tolerance, there is a variation in the relative position in the axial direction between the fitting portions of both members even in a state where they are connected to each other by a snap ring or the like. It is inevitable that the gap between the pressing portion of the one piston member and the friction engagement element varies. If it is attempted to reduce the gap, there is a possibility that a slight contact occurs, and the durability of the piston and the friction engagement element is lowered, and the drag loss is increased.

  On the other hand, in order to solve the above problem, a plurality of claw-like projections are integrally formed on the fitting portion of the second piston member to the first piston member, and the claw-like projections are made elastic. It is conceivable to configure to absorb this rattling. However, when configured in this manner, stress concentrates on the claw portion provided on the second piston, which is the fitting portion, and the fitting groove that receives the claw provided on the first piston, causing a problem in strength. It will be a thing.

  The present invention has been made against the background of the above circumstances. The object of the present invention is when the piston is composed of a first piston member constituting a cylindrical portion and a second piston member constituting a bottom portion. Another object is to improve the durability of the piston and the friction engagement element while maintaining high assembly accuracy.

  The gist of the invention according to claim 1 for achieving such an object is that a cylindrical first piston member is attached to the first piston in a state of being fitted into one end of the first piston member. A planetary gear type automatic transmission having a bottomed cylindrical piston provided with a circular second piston member, and (a) a stopper fixed to an inner peripheral surface of one end of the first piston member And (b) an elastic member that biases the second piston member toward the stopper in order to fix the second piston member to the first piston in close contact with the stopper. is there.

  In this way, the stopper fixed to the first piston member and the second piston member are in close contact with each other according to the urging force of the elastic member and are in surface contact with each other, so that high assembly accuracy is maintained. Further, the stress does not concentrate on specific portions of the first piston member and the second piston member, and the durability of these members can be improved.

  Here, preferably, the elastic member is a disc spring whose one end is received by a retaining ring removably attached to an annular groove formed on an inner peripheral surface of the one end of the first piston member. is there. If it does in this way, since a 2nd piston member is pressed toward a stopper by the disc spring which the one end part was received by the retaining ring, a structure is simple and it is between 1st piston member and 2nd piston member. The connecting mechanism becomes small.

  Preferably, the elastic member is a disc spring having one end received by an annular groove formed on an inner peripheral surface of one end of the first piston member. In this way, the second piston member is pressed toward the stopper by the disc spring whose one end is received by the retaining ring, so that the coupling mechanism between the first piston member and the second piston member is simplified. It becomes small. In addition, since the disc spring has one end received by the annular groove formed on the inner peripheral surface of the one end of the first piston member, a retaining ring for receiving the one end is not required, and the number of parts is reduced. Furthermore, the connecting mechanism is simplified and the size is reduced.

  Preferably, the stopper is a retaining ring detachably attached to an annular groove formed on an inner peripheral surface of one end of the first piston member. In this way, since the stopper can be attached and detached, assembly is facilitated even when other members are positioned with a slight gap on the inner peripheral side of the first piston member.

  Preferably, a second elastic member is interposed between the stopper and the second piston member. In this way, the rising of the transmission torque at the start of engagement of the clutch is suitably mitigated while enjoying the above effects.

  Preferably, a clutch drum is concentrically disposed on an inner peripheral side of the first piston member with a gap smaller than a radial protruding dimension of the retaining ring. In this way, even if the clutch drum is disposed concentrically with a gap smaller than the radial protruding dimension of the retaining ring on the inner peripheral side of the first piston member, assembly is facilitated.

  Preferably, a frictional engagement element pressed by the piston is provided, and a biasing direction of the elastic member against the second piston member and the piston when the frictional engagement element is engaged. The driving direction is the same. In this case, since the urging direction of the elastic member with respect to the second piston member is the same as the driving direction of the piston when the friction engagement element is engaged, the hydraulic pressure for operating the piston is all piston. There is an advantage that it will be used for the operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view illustrating a partial configuration of a planetary gear type automatic transmission 8 having an outer peripheral side piston 18 which is a piston according to an embodiment of the present invention.

  The automatic transmission 8 includes a plurality of sets of planetary gear units and a plurality of hydraulic type units that connect the rotating elements constituted by the elements of the planetary gear units independently or interconnected to each other or to a non-rotating member. And a stepped transmission of a type in which a plurality of gear stages are selectively established according to the type of combination of engagement operations of the plurality of hydraulic friction engagement devices. FIG. 1 shows a clutch device 10 having a double clutch structure for interconnecting some rotating elements of a planetary gear device of an automatic transmission 8. The clutch device 10 includes a bottomed cylindrical clutch drum 16 that supports a first friction engagement element 12 and a second friction engagement element 14 formed of a plurality of friction plates, and the clutch drum 16 on the outer peripheral side thereof. It has the outer peripheral side piston 18 arrange | positioned so that it may cover, and the inner peripheral side piston 20 arrange | positioned at the inner peripheral side of the clutch drum 16.

  The input shaft 22, which is a rotation shaft, is provided with a shaft end portion 22 a that is supported by a case 24 of the automatic transmission 8 via a bearing 23 so as to be relatively rotatable, and the input shaft 22 has a shaft end portion 22 a. Is formed with a flange 22b protruding radially outward in a direction perpendicular to the rotation axis C. The input shaft 22 is a turbine shaft (output shaft) of a torque converter (not shown) that is rotationally driven by a traveling drive source such as an engine, or a rotary shaft connected thereto.

  The clutch drum 16 as a whole has a bottomed cylindrical shape with the rotation axis C as a central axis, and includes a boss portion 26 at the center thereof. The boss portion 26 is a thick cylindrical member whose outer diameter is substantially constant in the axial direction, and is fitted to the outer peripheral surface of the axial tube portion 24 a protruding from the case 24 so as to be relatively rotatable. . The boss portion 26 includes a thin portion 26a in which the inner peripheral portion at the end on the inner peripheral piston 20 side in the axial direction is thin and the inner diameter is increased, and the inner peripheral surface of the thin portion 26a is provided on the inner peripheral surface of the thin portion 26a. A step portion 26b is formed. And the end surface of this thin part 26a is made to correspond with the surface at the inner peripheral side piston 20 side of the collar part 22b of the input shaft 22, and the boss | hub part 26 and the input shaft 22 are the collar part 22b of the input shaft 22. And the inner peripheral edge of the thin portion 26a of the boss portion 26 are joined to each other by welding. Thereby, the oil sump 30 is formed on the inner peripheral side of the step portion 26b.

  The clutch drum 16 is an integral bottomed cylindrical member that is formed by pressing from a steel plate and opens in one axial direction, and is a short cylindrical inner peripheral side joint portion 28a in which a boss portion 26 is joined to the inner peripheral edge. A disc-shaped bottom portion 28b having a cylindrical shape and a cylindrical tube portion 28c connected to the outer peripheral edge of the bottom portion 28b.

  The inner peripheral side joining portion 28a is disposed so as to fit to the outer periphery of the thin portion 26a of the boss portion 26, and the end surface on the inner peripheral side piston 20 side is on the inner peripheral side piston 20 side of the thin portion 26a of the boss portion 26 The inner peripheral edge of the inner peripheral side cylinder portion 28a and the outer peripheral edge of the thin portion 26a of the boss portion 26 are welded. Therefore, the clutch drum 16 is rotated integrally with the input shaft 22.

  The bottom portion 28b of the clutch drum 16 is provided substantially perpendicular to the radial direction of the input shaft 22, and is connected to the end portion of the inner peripheral side cylinder portion 28a on the outer peripheral side piston 18 side. The cylindrical portion 28c extends from the outer peripheral edge of the bottom portion 28b toward the inner peripheral piston 20, and a plurality of inward friction plates 32 of the first friction engagement element 12 are spline-fitted on the inner peripheral surface near the opening. Are combined. The first friction engagement element 12 includes a plurality of inward friction plates 32 and a plurality of outward friction plates 34 interposed between the plurality of inward friction plates 32. Furthermore, the inward friction plate 38 of the second friction engagement element 14 is spline-fitted on the bottom 28b side of the portion supporting the first friction engagement element 12. The second friction engagement element 14 includes the plurality of inward friction plates 38 and a plurality of outward friction plates 40 interposed between the plurality of inward friction plates 38.

  Further, the plurality of outward friction plates 34 of the first friction engagement element 12 are spline-fitted to the outer peripheral surface of the ring gear 36 that functions as a clutch hub, and the plurality of outward friction plates 40 of the second friction engagement element 14. Is spline-fitted to the outer peripheral surface of the clutch hub 42. Further, since the inner peripheral edge of the clutch hub 42 is fixed to a sun gear 44 fitted on the input shaft 22, the clutch hub 42 is rotated integrally with the sun gear 44.

  The outer peripheral side piston 18 is concentric with the clutch drum 16 so as to cover the outer side of the clutch drum 16 and has a bottomed cylindrical shape slightly larger in diameter than the clutch drum 16, and is positioned on the outer peripheral side of the cylindrical portion 28 c. A cylindrical first piston member 46 and an annular second piston member 48 which is fitted into one axial end of the first piston member 46 and forms the bottom of the outer piston 18. I have. The first piston member 46 and the second piston member 48 are also made of a steel plate by pressing.

  The second piston member 48 is slidably fitted to the outer peripheral surface of the stepped portion of the bottom portion 28 b and the outer peripheral surface of the boss portion 26, and the second piston member 48 and the bottom portion of the clutch drum 16. A first hydraulic chamber 52 is formed between the first hydraulic chamber 52 and the second hydraulic chamber 28b. The hydraulic oil is supplied to the first hydraulic chamber 52 via an oil passage 54 formed in the boss portion 26, and the hydraulic oil is supplied to the first hydraulic chamber 52. The second piston member 48 is moved in a direction away from the bottom 28 b of the clutch drum 16.

  On the back side of the second piston member 48 opposite to the first hydraulic chamber 52, a balancer 58 is fitted to the outer periphery of the boss portion 26, and the inner peripheral edge of the balancer 58 is opposite to the outer peripheral piston 18. The surface is brought into contact with a snap ring 64 fixed to the outer peripheral surface of the boss portion 26. Further, a return spring 62 is interposed between the balancer 58 and the second piston member 48 to urge them in a direction to separate them from each other. A second hydraulic chamber 60 for compensating the centrifugal hydraulic pressure is formed between the balancer 58 and the second piston member 48.

  A supply oil hole (not shown) that connects the second hydraulic chamber 60 and the oil reservoir 30 is formed in the boss portion 26, and hydraulic oil is supplied to the second hydraulic chamber 60 via the supply oil hole. Thus, the second hydraulic chamber 60 functions as a cancel chamber that cancels the centrifugal hydraulic pressure of the first hydraulic chamber 52. The hydraulic oil supplied to the second hydraulic chamber 60 passes through a groove 66 extending in the axial direction formed in a portion where the balancer 58 of the boss portion 26 is attached, and the back side of the balancer 58 (balancer). 58 on the side opposite to the second hydraulic chamber 60).

  The first piston member 46 of the outer peripheral side piston 18 is fitted with a cylindrical part 46a disposed on the outer peripheral side of the cylindrical part 28c of the clutch drum 16 with a slight gap and a second piston member 48 of the cylindrical part 46a. It is composed of a pressing portion 46b that is connected to an end portion on the opposite side to the joined side and that is directed radially inward and toward the first friction engagement element 12 in the axial direction. The radial position of the distal end (inner peripheral end) of the pressing portion 46b is a position facing the first friction engagement element 12, and the gap between the distal end of the pressing portion 46b and the first friction engagement element 12 is the same. In the state where the hydraulic oil is discharged from the first hydraulic chamber 52, an extremely narrow clearance is generated. Further, on the opposite side of the first friction engagement element 12 from the pressing portion 46b, the first friction engagement element 12 is fixed to the cylinder portion 28c of the clutch drum 16 and the second friction engagement element 14 in the axial direction is fixed. A snap ring 56 is provided to prevent movement to the side.

  2 shows that the contact portion between the first piston member 46 and the second piston member 48 (that is, the inner peripheral surface 46c of the cylindrical portion 46a of the first piston member 46 and the outer peripheral end of the second piston member 48 are substantially matched. It is sectional drawing which expands and shows the part which has contact | connected.

  As shown in detail in FIG. 2, on the inner peripheral surface of one end portion of the first piston member 46, two first pieces along the circumferential direction are spaced at intervals sufficiently larger than the plate thickness of the second piston member 48. An annular groove 50 and a second annular groove 51 are formed, and a first snap ring 70 and a second snap ring 72 are fitted into the first annular groove 50 and the second annular groove 51. The outer peripheral edge of the second piston member 48 is positioned between the first snap ring 70 and the second snap ring 72, and the second piston member 48 and the second snap ring 72 A conical and annular disc spring 74 to which a predetermined preload is applied is interposed therebetween. The first snap ring 70 serves as a stopper for preventing the second piston member 48 fitted in the first piston member 46 from moving away from the first piston member 46, that is, moving to the left in FIG. It functions. The second snap ring 72 functions as a spring receiver for fixing one end of the disc spring 74, and the second piston member 48 enters the first piston member 46 via the disc spring 74, that is, in FIG. It functions as a stopper for preventing movement to the right. Accordingly, the second piston member 48 is integrally attached in a state of being fitted into one end portion of the first piston member 46. Further, the second piston member 48 is urged toward the first snap ring 70 by the disc spring 74 and is always brought into close contact with one surface of the first snap ring 70, so that the assembly accuracy of the outer peripheral side piston 18 is improved. It is like that. Thereby, after assembling, a gap of about 0.5 mm is stably formed between the pressing portion 46b and the inward friction plate 32 regardless of the existence of dimensional tolerances and machining tolerances of each part.

  A slight gap G between the inner peripheral surface 46 c of the cylindrical portion 46 a of the first piston member 46 and the outer peripheral surface of the cylindrical portion 28 c of the clutch drum 16 is the inner periphery of the first snap ring 70 and the second snap ring 72. The first snap ring 70 and the second snap ring 72 are detachably attached to the first annular groove 50 and the second annular groove 51, respectively. Therefore, it can be assembled.

  As described above, according to the outer peripheral side piston 18 of the automatic transmission 8 of the present embodiment, the first snap ring (stopper) 70 fixed to the first piston member 46 and the second piston member 48 are provided. According to the urging force of the disc spring (elastic member) 74, they come into close contact with each other and come into surface contact with each other, so that high assembly accuracy is maintained. Further, stress is not concentrated on specific portions of the first piston member 46 and the second piston member 48, and the durability of these members can be improved. Further, rattling that occurs in the axial direction between the first piston member 46 and the second piston member 48 due to gaps unavoidably present due to component tolerances and machining tolerances is preferably prevented.

  Moreover, according to the outer peripheral side piston 18 of the automatic transmission 8 of the present embodiment, the disc spring 74 is detachably attached to the second annular groove 51 formed on the inner peripheral surface of one end portion of the first piston member 46. One end portion is received by the snap ring (retaining ring) 72, and the second piston member 48 is pressed toward the first snap ring (stopper) 70 by the disc spring 74 receiving the one end portion. The structure of the coupling mechanism between the first piston member 46 and the second piston 48 is simplified and the size is reduced.

  Further, according to the outer peripheral side piston 18 of the automatic transmission 8 of the present embodiment, the stopper is detachably attached to the first annular groove 50 formed on the inner peripheral surface of the one end portion of the first piston member 46. Since it is the first snap ring (retaining ring) 70, the first snap ring (retaining ring) 70 is attached / detached after another member is incorporated on the inner peripheral side of the first piston member 46 with a slight clearance. Therefore, even when other members are located on the inner peripheral side of the first piston member 46 with a slight gap, assembly is facilitated.

  Further, according to the outer peripheral side piston 18 of the automatic transmission 8 of the present embodiment, the first snap ring (retaining ring) 70 or the second snap ring (retaining ring) 72 is provided on the inner peripheral side of the first piston member 46. Since the clutch drum 16 is concentrically arranged with a gap smaller than the inner peripheral radial protrusion dimension H of the first piston member 46, the inner peripheral radial protrusion dimension H is provided on the inner peripheral side of the first piston member 46. Even if the clutch drum 16 is disposed concentrically with a smaller gap G, assembly is facilitated.

  Further, according to the outer peripheral side piston 18 of the automatic transmission 8 of this embodiment, the outer peripheral side piston when the first friction engagement element 12 is engaged with the biasing direction of the disc spring 74 with respect to the second piston member 48. Since the drive direction of 18 is the same, all the hydraulic pressures that actuate the outer piston 18 are used for the operation of the piston.

  Next, another embodiment of the present invention will be described. In the following description, parts common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

  FIG. 3 is a diagram of another embodiment of the present invention and corresponds to FIG. 1 of the first embodiment described above. In this embodiment, instead of the second snap ring 72 and the disc spring 74 in the first embodiment, a snap ring 76 having a disc spring function having elasticity in the radial direction and the axis C direction is used. 4 and 5 are a sectional view and a perspective view of a snap ring 76 having a disc spring function, respectively. The disc spring 74 of the above-mentioned embodiment has a feature that the material yield is low because it is manufactured in a conical and annular shape by punching a flat plate made of spring steel. However, the snap ring 76 having the disc spring function of the embodiment is used. Since, for example, a ribbon-like or linear plate material is bent into a conical and partly discontinuous ring shape, the material yield is high. Of course, also in the above-described embodiment, a snap ring 76 having this disc spring function may be used instead of the disc spring 74.

  FIG. 6 shows a connecting portion between the first piston member 46 and the second piston member 48, that is, a portion where the inner surface 46 c of the cylindrical portion 46 a of the first piston member 46 and the outer peripheral end of the second piston member 48 are in contact with each other. It is sectional drawing which expands and shows. On the inner peripheral surface 46c of the first piston member 46, a first snap ring 70 is mounted in the first annular groove 50 on the opening side of the outer peripheral side piston 18 relative to the second piston member 48, that is, on the left side in the figure. The piston member 48 comes into contact with the first snap ring 70 and stops. Further, on the inner peripheral surface 46 c of the first piston member 46, on the opposite side via the first snap ring 70 and the second piston member 48, that is, on the right side of the second piston member 48, the above-described second annular groove 51. An annular groove 78 having a large width is also provided.

  The snap ring 76 having a disc spring function is received by receiving the outer peripheral end of the snap ring 76 in the annular groove 78. The inner peripheral end of the snap ring 76 contacts the second piston member 48, and the first snap ring 70, that is, the piston. Is always energized to the left side of the figure. The snap ring 76 having a disc spring function is inserted between the second piston member 48 and the annular groove 78 in a state where a preload is applied. As a result, the piston outer peripheral side surface 48d of the second piston member 48 and the first snap ring 70 are brought into surface contact in a close contact state. The annular groove 78 also functions as a mounting groove for the snap ring 76 having a disc spring function.

  Thus, since the snap ring 76 having a disc spring function biases the second piston member 48, the piston outer peripheral side surface 48d of the second piston member 48 and the first snap ring 70 are brought into close contact with each other. The same effect as the above-described embodiment can be obtained.

  Further, according to the outer peripheral side piston 18 of the automatic transmission 8 of the present embodiment, the snap ring 76 having a disc spring function is one end by the annular groove 78 formed on the inner peripheral surface of one end portion of the first piston member 46. Since the portion is received, the second snap ring 72 for receiving one end portion of the disc spring 74 as in the above-described embodiment in the connecting mechanism between the first piston member 46 and the second piston member 48. Is eliminated, the number of parts is reduced, and the connecting mechanism is further simplified and reduced in size.

  FIG. 7 shows the outer peripheral side piston 18 in which the disc spring 75 corresponding to the second elastic member is inserted between the second piston member 48 and the first snap ring 70 in the embodiment of FIGS. ing. According to the present embodiment, the disc spring 75 is also interposed between the first snap ring 70 functioning as a stopper and the second piston member 48, so that the clutch can be enjoyed while enjoying the effects of the above-described embodiment. The rise of the transmission torque at the start of the engagement is preferably alleviated.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the first snap ring 70 is detachably attached to the first annular groove 51 as a stopper, but a non-detachable member is fixed to the first piston member 46 as a stopper. Good.

  In the first embodiment, the disc spring 74 is used as a member that has elasticity in the axial direction and constantly biases the second piston 48. However, the present invention is not limited to this, and other members are used. Also good. Similarly, in the above-described second embodiment, the snap ring 76 having a disc spring function is used as a snap ring that has elasticity in the axial direction and constantly biases the second piston, but is not limited thereto. Other members may be used. For example, an annular spring in which a large number of irregularities are formed in a corrugated shape may be used.

  In the above-described embodiment, the present invention is applied to the piston 18 that operates the clutch of the planetary gear type automatic transmission. However, the present invention can also be applied to a brake piston.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

It is principal part sectional drawing explaining the principal part of the planetary gear type automatic transmission of one Example of this invention. In the automatic transmission of FIG. 1, it is sectional drawing which expands and shows the mechanism of the connection part of the 1st piston member and 2nd piston member which comprise a piston. It is principal part sectional drawing explaining the principal part of the planetary gear type automatic transmission of the other Example of this invention, and is a figure equivalent to FIG. It is sectional drawing of the snap ring with a disc spring function used for the Example of FIG. FIG. 4 is a perspective view of a snap ring having a disc spring function used in the embodiment of FIG. 3. FIG. 4 is an enlarged cross-sectional view illustrating a mechanism of a connecting portion between a first piston member and a second piston member constituting the piston in the embodiment of FIG. 3 and corresponds to FIG. 2. It is a figure showing another embodiment in the Example of this invention, and is a figure corresponding to FIG.

Explanation of symbols

8: Automatic transmission 18: Outer piston 46: First piston member 48: Second piston member 70: First snap ring (stopper, retaining ring)
72: Second snap ring (retaining ring)
74: Disc spring 76: Snap ring with disc spring function

Claims (7)

A planet having a bottomed cylindrical piston having a cylindrical first piston member and a circular second piston member fitted to the first piston in a state of being fitted into one end of the first piston member A gear-type automatic transmission,
A stopper fixed to the inner peripheral surface of one end of the first piston member;
A planetary gear comprising: an elastic member that urges the second piston member toward the stopper in order to fix the second piston member to the first piston in close contact with the stopper. Type automatic transmission.   The elastic member is a disc spring whose one end is received by a retaining ring removably attached to an annular groove formed on an inner peripheral surface of one end of the first piston member. Item 1. The planetary gear automatic transmission according to Item 1.   2. The planetary gear type automatic transmission according to claim 1, wherein the elastic member is a disc spring whose one end is received by an annular groove formed in an inner peripheral surface of one end of the first piston member. .   4. The planetary gear type according to claim 1, wherein the stopper is a retaining ring detachably attached to an annular groove formed on an inner peripheral surface of one end portion of the first piston member. 5. Automatic transmission.   The planetary gear automatic transmission according to any one of claims 1 to 4, wherein a second elastic member is interposed between the stopper and the second piston member.   5. The clutch drum is disposed concentrically on the inner peripheral side of the first piston member with a gap smaller than the radial protruding dimension of the retaining ring. The planetary gear type automatic transmission. A friction engagement element pressed by the piston is provided;
The urging direction of the elastic member with respect to the second piston member is the same as the driving direction of the piston when the friction engagement element is engaged. Planetary gear type automatic transmission.

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