JP7522145B2 - Torque converter lockup device - Google Patents

Description

The present invention relates to a lockup device for a torque converter that is interposed between, for example, the crankshaft of a vehicle engine and the input shaft of a transmission.

The torque converter incorporated in the automatic transmission for a vehicle is equipped with a lockup device that directly connects the input side and the output side in order to improve fuel efficiency. The lockup device is equipped with a lockup clutch and a lockup damper (torsional vibration damper). The lockup clutch has a friction element on the input side, a friction element on the output side, and a lockup piston that presses these friction elements against each other. The lockup piston forms an oil chamber between itself and an adjacent component adjacent to it in the axial direction (e.g., a torque converter cover, a piston guide). The lockup piston operates when hydraulic oil is supplied to this oil chamber. A seal member is provided between the lockup piston and the adjacent component to seal the oil chamber.

If the lockup piston rotates relative to the adjacent components, it may cause significant wear or damage to the seal member. For this reason, the lockup piston is provided with a rotation prevention mechanism to prevent the relative rotation (see, for example, Patent Documents 1 to 3). Known rotation prevention mechanisms have drawbacks such as a complex structure and an increased number of parts.

JP 2011-117517 A US Patent Publication No. 2020158219 Korean Patent No. 101989072

The present invention provides a torque converter lockup device equipped with a rotation prevention mechanism that has a simple and compact structure and can be manufactured at low cost.

According to one embodiment of the present invention, a lockup device for a torque converter includes a friction engagement mechanism having an input portion having a friction disc and an output portion having a friction disc, a lockup piston that moves in the direction of the rotation axis of the lockup device to press the friction engagement mechanism and frictionally engage the input portion and the output portion of the friction engagement mechanism, a piston guide portion that is coupled to the input portion so as to rotate together with the input portion of the friction engagement mechanism and guides the movement of the lockup piston in the direction of the rotation axis, and a rotation prevention mechanism that disables the relative rotation of the lockup piston with respect to the piston guide portion while enabling relative movement in the direction of the rotation axis. The lockup piston has a side wall portion that extends generally in the radial direction, and the side wall portion and a substantially cylindrical first peripheral wall portion extending from the periphery of the piston guide in the direction of the rotation axis, the first peripheral wall portion being slidable on the substantially cylindrical first guide surface of the piston guide, a plurality of recesses being provided at intervals in the circumferential direction at a free end, which is the end of the first peripheral wall portion in the direction of the rotation axis, each of the recesses extending in the direction of the rotation axis from the free end of the first peripheral wall portion and penetrating the entire thickness of the first peripheral wall portion in the radial direction, the piston guide portion having a plurality of teeth protruding in the radial direction from the first guide surface and respectively slidably engaging with the plurality of recesses of the lock-up piston, and the rotation prevention mechanism being constituted by the plurality of recesses and the plurality of teeth.

According to the above embodiment of the present invention, it is possible to obtain a lockup device equipped with a rotation prevention mechanism that has a simple and compact structure and can be manufactured at low cost.

1 is a vertical sectional view in an axial direction of a torque converter including a lockup device according to an embodiment of the present invention; FIG. 2 is an enlarged view showing a lock-up piston, a piston guide, and a cover hub extracted from FIG. 1 . FIG. 2 is an exploded perspective view of the lockup piston and the cover hub shown in FIG. 1 . FIG. 4 is a perspective view showing a state in which the lock-up piston shown in FIG. 3 is assembled to a cover hub. FIG. 11 is a schematic diagram of a torque converter including a lock-up device according to another embodiment of the present invention.

Below, an embodiment of a lockup device and a torque converter equipped with a lockup device will be described with reference to the drawings.

Figure 1 is an axial longitudinal cross-sectional view showing the structure surrounding a torque converter 10 and a lockup device 30 of an automobile power transmission device. In this specification, the term "axial direction" means the direction of the central axis Ax of the rotation shaft of the torque converter 10 and the lockup device 30, unless otherwise specified. In this specification, the term "radial direction" means a direction perpendicular to the central axis Ax, unless otherwise specified. In this specification, the terms "circumference" and "circumferential direction" mean the circumference or direction of a circle that is centered on a point on the central axis Ax and lies on a plane perpendicular to the central axis Ax, unless otherwise specified.

The torque converter 10 has a cover (input side cover) 11, an impeller 12, a turbine 13, and a stator 14. The cover 11 is connected to a cover hub 15 by welding or other means so that it cannot rotate relative to the cover hub 15. The cover 11 is provided with a drive plate mounting boss 11A. A drive plate (not shown) fixed to the crankshaft (not shown) of the internal combustion engine is attached to the drive plate mounting boss 11A. Rotational torque is input from the internal combustion engine to the cover 11 of the torque converter 10 via this drive plate.

The impeller 12 is covered by an impeller shell 16. The impeller shell 16 is connected to the cover 11 by means of welding or other means so that it cannot rotate relative to the cover 11. The stator 14 is fixed to a fixed shaft 18 via a one-way clutch 17.

When the lockup device 30 is released (not locked up), the rotational torque input to the cover 11 is transmitted to the input shaft 20 of a transmission (e.g., a planetary gear transmission) (not shown) via the impeller 12, turbine 13, and turbine hub 19. The functions of the impeller 12, turbine 13, and stator 14 at this time are well known in the technical field of automotive power transmission devices, so a detailed description will be omitted.

Note that the reference symbol "ENG" in Figure 1 indicates that an engine is located nearby, and the reference symbol "TM" indicates that a transmission is located nearby.

The lockup device 30 has a lockup clutch 31 and a lockup damper 40.

The illustrated lock-up damper (torsional vibration damper) 40 has an input side retainer plate 41, an output side retainer plate 42, an auxiliary retainer plate 43, and an outer retainer plate 44.

The lock-up damper 40 further has a number of main springs 45 and a number of secondary springs 46 that act to resist relative rotation between the input side retainer plate 41 and the output side retainer plate 42.

The output side retainer plate 42, the auxiliary retainer plate 43, and the turbine 13 are attached to the turbine hub 19 via fastening members such as rivets. Therefore, the output side retainer plate 42, the auxiliary retainer plate 43, and the turbine 13 cannot rotate relative to one another.

The lock-up clutch 31 has a friction engagement portion consisting of an input portion 311 connected to the cover 11 so as not to rotate relative thereto and an output portion 312 connected to the input side retainer plate 41 so as not to rotate relative thereto, and a lock-up piston 32. The input portion 311 and the output portion 312 each have a plurality of friction discs. The lock-up piston 32 is supported by a piston guide 314 and a cover hub 15 so as to be movable in the axial direction (described in detail below). In other words, the piston guide 314 and the cover hub 15 form a piston guide portion.

An oil chamber 315 is formed between the lock-up piston 32 and the piston guide 314 in the axial direction. Hydraulic oil can be supplied to the oil chamber 315 via an oil passage 316 formed in the cover hub 15.

An oil chamber 33 is formed between the lock-up piston 32 and the cover 11 in the axial direction. Hydraulic oil is supplied to the oil chamber 33 via an oil passage 34 formed in the cover hub 15. The hydraulic oil supplied to the oil chamber 33 is supplied to the friction disks of the input part 311 and output part 312 of the lock-up clutch 31, the impeller 12, the turbine hub 19, the lock-up damper 40, etc.

When the engine is running, hydraulic oil is supplied to the oil chamber 33. Therefore, the lock-up piston 32 is biased to the left (TM side) in Figure 1 by the hydraulic pressure in the oil chamber 33.

When hydraulic oil is supplied to the oil chamber 315 and the pressure in the oil chamber 315 exceeds the pressure in the oil chamber 33, the lock-up piston 32 is displaced to the right (ENG side) in FIG. 1, and the lock-up piston 32 (particularly the disk pressing portion 321a described below) presses the friction disk of the input portion 311 against the friction disk of the output portion 312. As a result, the input portion 311 and the output portion 312 (friction engagement portion) frictionally engage with each other, and the lock-up clutch 31 enters a locked-up (engaged) state.

At this time, the engine power input to the cover 11 is transmitted to the turbine hub 19 via the input part 311, the output part 312, and the lock-up damper 40 of the lock-up clutch 31. At this time, the lock-up damper 40 damps torsional vibrations by a mechanism of action well known in the technical field of automotive power transmission devices.

When the hydraulic oil pressure in the oil chamber 315 is released, the hydraulic oil pressure in the oil chamber 33 hydraulically displaces the lock-up piston 32 in the direction shown in FIG. 1 (towards TM), and the lock-up state is released.

Next, the lock-up piston 32 and the piston guide portion (piston guide 314 and cover hub 15), as well as the anti-rotation structure of the lock-up piston 32 will be described in detail with reference to Figures 2 to 4.

The lock-up piston 32 is formed as a rotating body in a geometric sense (excluding the recess 325 described below). The rotation axis of this rotating body coincides with the central axis Ax of the torque converter and the lock-up clutch.

The lock-up piston 32 has a generally ring-shaped disk-shaped side wall portion 320 as a whole, a generally cylindrical inner wall portion (first wall portion) 321 extending axially from the inner peripheral edge of the side wall portion 320, and a generally cylindrical outer wall portion (second wall portion) 322 extending axially from the outer peripheral edge of the side wall portion 320. For ease of explanation, the axial direction toward the left side of the figure (TM side) will be referred to as the positive direction of the rotation axis, and the axial direction toward the right side of the figure (ENG side) will be referred to as the negative direction of the rotation axis. In the illustrated embodiment, the inner wall portion 321 and the outer wall portion 322 extend from the side wall portion 320 in the same direction (positive direction of the rotation axis).

The side wall portion 320 generally expands in the radial direction as a whole. Near the outer periphery of the side wall portion 320, a disk pressing portion 321a is formed that protrudes in the negative direction of the rotation axis and extends continuously in the circumferential direction. The disk pressing portion 321a serves to press the friction disk of the input portion 311 in the negative direction of the rotation axis during lockup.

A stopper portion 321b is formed on the side wall portion 321 at a position radially inward from the disk pressing portion 321a. The stopper portion 321b protrudes in the positive direction of the rotation axis and extends continuously in the circumferential direction. When there is no lockup, the stopper portion 321b comes into contact (particularly surface contact) with the piston guide 314, stopping the lockup piston 32 at a predetermined axial position.

The outer peripheral wall portion 322 (particularly its inner peripheral surface) of the lock-up piston 32 is guided so as to be able to slide in the direction of the rotation axis on the piston guide 314 (particularly its outermost peripheral surface 319 (second guide surface)) fixed to the cover hub 15 by means of welding or the like. The piston guide 314 can also be said to be a (second) piston guide portion that supports and guides the outer peripheral wall portion 322 (particularly its inner peripheral surface) of the lock-up piston 32.

The piston guide 314 has a ring shape that generally expands in the radial direction as a whole. The diameter of the outermost surface 319 of the piston guide 314 is slightly smaller than the diameter of the inner surface of the outer peripheral wall portion 322 of the lock-up piston 32. A circumferential groove is formed in the outermost surface 319 of the piston guide 314, and a ring-shaped seal member 317 is attached to this circumferential groove. In order to seal the oil chamber 315, the seal member 317 seals between the inner surface of the outer peripheral wall portion 322 of the lock-up piston 32 and the outermost surface 319 of the piston guide 314 with an appropriate interference that allows axial movement of the lock-up piston 32.

The cover hub 15 is provided with a piston guide portion 151. In the illustrated embodiment, the piston guide portion 151 is formed as a generally ring-shaped protrusion that protrudes radially outward from a portion of the cover hub 15 adjacent to the piston guide portion 151. The inner peripheral wall portion 321 (particularly its inner peripheral surface) of the lock-up piston 32 is guided so as to be able to slide in the direction of the rotation axis on the piston guide portion 151 (particularly its outer peripheral surface 152 (first guide surface)).

The diameter of the outer peripheral surface 152 of the piston guide portion 151 is slightly smaller than the diameter of the inner peripheral surface of the inner peripheral wall portion 321 of the lock-up piston 32. A circumferential groove is formed in the outer peripheral surface 152, and a ring-shaped seal member 318 is attached to this circumferential groove. In order to seal the oil chamber 315, the seal member 318 seals between the inner peripheral surface of the inner peripheral wall portion 321 of the lock-up piston 32 and the outer peripheral surface 152 of the piston guide portion 151 with an appropriate interference that allows the lock-up piston 32 to move in the axial direction.

A plurality of teeth 154 (six in the illustrated example) protrude radially outward from the outer circumferential surface 152 of the piston guide portion 151. The teeth 154 are equally spaced in the circumferential direction. In the illustrated embodiment, the teeth 154 have a generally rectangular cross section. That is, the teeth 154 are provided in a spline-like configuration.

At angular positions corresponding to the teeth 154 of the piston guide 151, a number of recesses 325 are formed in the tip of the inner wall portion 321 of the lock-up piston 32 (i.e., the ring-shaped free end opposite the side wall portion 320 and its vicinity). The recesses 325 extend from the tip (free end) of the inner wall portion 321 in the negative direction of the rotation axis and penetrate the entire thickness of the inner wall portion 321 in the radial direction.

The circumferential width of the recess 325 is slightly larger than the circumferential width of the tooth 154. The depth (axial depth) of the recess 325 is sized so that the tooth 154 does not come out of the recess 325 even when the lock-up piston 32 is displaced to its maximum in the negative direction of the rotation shaft.

The above-mentioned configuration of the piston guide portion 151 of the cover hub 15 and the configuration of the inner peripheral wall portion 321 of the lock-up piston 32 allow the lock-up piston 32 to be attached to the cover hub 15 so as to be non-rotatable relative to the cover hub 15 but movable in the axial direction. The lock-up piston 32 can also be made non-rotatable but movable in the axial direction relative to the piston guide 314, which is fixed non-rotatable relative to the cover hub 15. As a result, the seal members 317, 318 do not slide in the rotational direction relative to the lock-up piston 32, and wear of the seal members 317, 318 can be prevented.

According to the above embodiment, as is clear from the shapes shown in Figures 2 to 4, the lock-up piston 32 can be formed by pressing a plate material made of a metal material, particularly a steel material, and particularly by drawing. The recess 325 formed in the inner peripheral wall portion 321 can be formed by one step of pressing (e.g., punching). In this case, the manufacturing cost of the lock-up piston 32 can be reduced. The recess 325 may be formed by cutting after pressing (in this case, the recess 325 is not formed), or may be formed by forming the rough shape of the recess 325 by pressing and then performing finishing cutting or polishing. As is clear from the shape, regardless of which manufacturing method is adopted, the recess 325 can be easily formed. Therefore, the lock-up piston 32 can be prevented from rotating at low cost. In addition, there is no need to prepare an extra separate part for preventing rotation. Therefore, the manufacturing cost of the lock-up clutch and the torque converter equipped therewith can be reduced.

It is also easy to form teeth 154 on the cover hub 15 to fit into the recesses 325. Note that the member on which the teeth 154 are formed may be formed separately from the cover hub 15 and then joined to the cover hub 15.

According to the above embodiment, the inner peripheral wall portion 321 and the outer peripheral wall portion 322 extend from the side wall portion 321 in the same direction (the positive direction of the rotation axis), so the number of steps required to press the lock-up piston 32 can be reduced. However, the inner peripheral wall portion 321 and the outer peripheral wall portion 322 may extend in opposite directions.

According to the above embodiment, since the part (recess 325) involved in preventing the lock-up piston 32 from rotating is provided on the inner wall portion 321, the shape of the side wall portion 321 can be set more freely than when the part involved in preventing the lock-up piston 32 is provided on the side wall portion 321. This increases the degree of freedom in the shape design that achieves both improved rigidity of the lock-up piston 32 and avoidance of stress concentration. It is also possible to provide the part (recess 325) involved in preventing the lock-up piston 32 from rotating on the outer wall portion 322. However, from the viewpoint of ease of manufacture, it is preferable to provide the part (tooth 154) that engages with the part involved in preventing the lock-up piston 32 from rotating on the cover hub 15, so it is preferable to provide the part (recess 325) involved in preventing the lock-up piston 32 from rotating on the inner wall portion 321.

According to the above embodiment, the inner peripheral surface of the inner peripheral wall portion 321 is guided on the outer peripheral surface of the piston guide portion 151, and the inner peripheral surface of the outer peripheral wall portion 322 is guided on the outermost peripheral surface 319 of the piston guide 314. Therefore, it is not necessary to attach a seal member to the lock-up piston 32, and it is sufficient to attach a seal member to the mating member. In other words, since it is not necessary to form grooves for attaching a seal in the inner peripheral wall portion 321 and the outer peripheral wall portion 322, the thickness of the inner peripheral wall portion 321 and the outer peripheral wall portion 322 can be small. Therefore, it is possible to easily press-form the lock-up piston 32 from a single plate material.

In order to quickly release the lockup, at least one return spring 50 (schematically shown by a broken line in FIG. 1) may be additionally provided to bias the lockup piston 32 to the left in the figure (toward the TM side). The return spring may be interposed between the cover 11 (or the input portion 311) and the lockup piston 32. The return spring 50 may be a single disc spring. The return spring 50 may be a plurality of coil springs arranged at equal intervals in the circumferential direction. In the latter case, a spring retainer is provided to hold the coil spring in a predetermined position. The return spring 50 only needs to be fixed to the cover 11 (or the input portion 311) so as not to rotate relative thereto, and only needs to be in contact with the lockup piston 32. In other words, since there is no need for a means (such as a rivet) for fixing the return spring 50 to the lockup piston 32, the configuration of the lockup piston 32 is not complicated by providing the return spring 50.

As shown diagrammatically in FIG. 5, an oil chamber 315 may be formed between the cover 11 and the lock-up piston 32. In FIG. 5, the same reference numerals are used for components that have the same functions as those shown in FIGS. 1 to 4. The outer peripheral wall portion 322 of the lock-up piston 32 is supported by the cover 11, and the inner peripheral wall portion 321 is supported by the cover hub 15. In this case, the anti-rotation structure may be provided in the inner peripheral wall portion 321 and the cover hub 15.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

11 Torque converter cover 311 Input portion of friction engagement mechanism 312 Output portion of friction engagement mechanism 32 Lock-up piston 320 Side wall portion of lock-up piston 321 First peripheral wall portion (inner peripheral wall portion) of lock-up piston
322 Second peripheral wall portion (outer peripheral wall portion) of lock-up piston
314, 151 Piston guide portion 314 Piston guide 319 Second guide surface (outermost peripheral surface of piston guide)
15 Cover hub 151 Piston guide portion of cover hub 152 First guide surface (outer peripheral surface of piston guide portion 151)
325, 154 Anti-rotation mechanism for lock-up piston 325 Recess 154 Teeth 317, 318 Seal member

Claims (7)

A lock-up device for a torque converter, comprising:
a friction engagement mechanism having an input portion having a friction disc and an output portion having a friction disc;
a lock-up piston that moves in a rotational axis direction of the lock-up device to press the friction engagement mechanism and frictionally engage the input portion and the output portion of the friction engagement mechanism;
a piston guide portion coupled to the input portion of the friction engagement mechanism so as to rotate together with the input portion, the piston guide portion guiding movement of the lock-up piston in the direction of the rotation axis;
a rotation prevention mechanism that prevents the lock-up piston from rotating relative to the piston guide portion while allowing the lock-up piston to move relative to the piston guide portion in the direction of the rotation axis;
Equipped with
The lock-up piston has a side wall portion extending generally in a radial direction and a first peripheral wall portion having a generally cylindrical shape extending from a peripheral edge portion of the side wall portion in the direction of the rotation axis,
the first peripheral wall portion is slidable on a substantially cylindrical first guide surface of the piston guide portion;
a plurality of recesses are provided at intervals in a circumferential direction at a free end, which is an end of the first peripheral wall portion with respect to the rotation axis direction, and each of the recesses extends from the free end of the first peripheral wall portion in the rotation axis direction and radially penetrates the entire thickness of the first peripheral wall portion;
the piston guide portion has a plurality of teeth protruding in a radial direction from the first guide surface and slidably fitted into the plurality of recesses of the lock-up piston,
a lockup device, characterized in that the anti-rotation mechanism is formed by the plurality of recesses and the plurality of teeth. The lockup device according to claim 1, wherein the first peripheral wall portion extends in the direction of the rotation axis from the inner peripheral edge of the sidewall portion, and the lockup piston further has a substantially cylindrical second peripheral wall portion extending in the direction of the rotation axis from the outer peripheral edge of the sidewall portion, and the second peripheral wall portion is capable of sliding on a substantially cylindrical second guide surface of the piston guide portion. The lockup device according to claim 2, wherein the first peripheral wall portion and the second peripheral wall portion extend from the side wall portion in the same direction relative to the rotation axis direction. The lockup device according to claim 2 or 3, wherein a first seal member is attached to the first guide surface to seal between the first guide surface and the first peripheral wall portion, and a second seal member is attached to the second guide surface to seal between the second guide surface and the second peripheral wall portion. The lockup device according to any one of claims 2 to 4, wherein a cover hub fixed non-rotatably to a torque converter cover to which the input part of the friction engagement mechanism is fixed non-rotatably forms at least a part of the piston guide part, and the first guide surface and the plurality of teeth are provided on the cover hub. The lockup device according to claim 5, wherein a plate-shaped piston guide fixed non-rotatably to the cover hub forms at least a part of the piston guide portion, and an oil chamber is formed by the lockup piston, the cover hub, and the piston guide. The lockup device according to any one of claims 1 to 6, wherein the lockup piston is a one-piece part formed from a single plate material.