JPH09242784A - Clutch for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clutch for an automatic transmission by which the service life of an oil seal part constituted between the outer periphery of a piston and the inner periphery of a cylinder can be lengthened and which is excellent in responsiveness. SOLUTION: In a clutch for an automatic transmission to engage the clutch by advancing a piston 4 by a prescribed quantity or more by supplying oil pressure to an oil chamber 12 of a cylinder 5, the outer periphery of its piston 4 and the inner periphery of the cylinder 5 are formed so as to become a noncontact condition until the piston 4 is advanced by a prescribed quantity or more, and when the piston 4 is advanced by the prescribed quantity or more, an annular contact part 11 formed on the outer peripheral front end side of the piston 4 and an annular projecting part 17 formed on the inner periphery of the cylinder 5 engage with each other, and fulfill an oil seal function, and generate necessary engaging pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch for an automatic transmission equipped with a hydraulic operating mechanism composed of a piston and a cylinder.

[0002]

2. Description of the Related Art An automatic transmission for a vehicle such as an automobile using an internal combustion engine as a drive source is provided with a torque converter for converting the drive torque of the internal combustion engine and a gear type speed change mechanism having an auxiliary function of the torque converter. The drive torque converted by the torque converter is further converted by the gear type speed change mechanism as needed.

As the gear type speed change mechanism, generally, one which obtains a required speed change mesh by a coupling device such as a plurality of clutches and brakes operated by a hydraulic control device is used. The automatic transmission clutch used as this coupling device includes a hydraulic operating mechanism including a piston and a cylinder that operates according to the hydraulic pressure supplied from the hydraulic control device.

The oil remaining in the oil chamber of the piston / cylinder is irrelevant to the fact that the hydraulic control device operates to release the engagement of the clutch for the automatic transmission when the clutch for the automatic transmission is rotated at a high speed. Since the hydraulic pressure generated by the centrifugal force, that is, the centrifugal hydraulic pressure causes the clutch for the automatic transmission to engage, the so-called clutch drag is caused.

For this reason, the piston and cylinder of the conventional automatic transmission clutch described above may be provided with an oil check valve in order to prevent the clutch from dragging by removing the oil remaining in the oil chamber.

For example, FIG. 7 shows an oil check valve 37.
FIG. 1 shows an example of a conventional multi-plate clutch provided with an oil check valve 37 that prevents an increase in pressure in the oil chamber 38 until the piston is advanced by a predetermined amount or more. Centrifugal oil pressure is generated in the oil accumulated on the side, causing drag of the clutch,
When the clutch is engaged, there is a problem in that the fastening force changes as the rotational speed increases and decreases.

Therefore, as an improved device, an automatic transmission clutch described in Japanese Utility Model Laid-Open No. 52-108467 is known.

This conventional automatic transmission clutch is shown in FIG.
As shown in FIG. 5, a leak passage 29 is provided between the outer circumference of the piston 21 and the inner circumference of the cylinder 22 to connect the oil chamber side of the piston 21 and the friction plate side.
A groove 23 is formed on the outer circumference of the piston 21, and an O-ring 24 is provided in the groove 23. The groove is formed on the inner circumference of the cylinder 22 so as to be deep on one side of the piston 21 and shallow on the other side. Ruptured part 25
8 is formed at several positions, and the effective diameter of the leak passage 29 between the outer circumference of the piston 21 and the inner circumference of the cylinder 22 is set to the forward movement of the piston 21, that is, from the position of FIG. 8A to that of FIG. 8B. It is configured such that it is gradually reduced with the sliding of the clutch to the clutch engagement position.

According to this automatic transmission clutch, when the hydraulic pressure generated by the centrifugal force starts to be supplied to the oil chamber 26, a part of the hydraulic pressure supplied to the oil chamber 26 passes through the leak passage 29 and then moves to the oil chamber 26. Leaked from 26.

Therefore, even when a relatively high oil pressure is supplied to the oil chamber 26, the clutch plate 27 and the clutch disc 28 are gradually engaged, and the oil chamber 26 remains in the oil chamber 26 until the piston is advanced by a predetermined amount or more. Since the hydraulic pressure is guided to the outside, the hydraulic pressure generated by the centrifugal force, that is, the centrifugal hydraulic pressure can be released from the leak passage 29, and the drag of the clutch can be prevented. Further, it is possible to prevent a change in the engaging force of the clutch due to an increase / decrease in the rotational speed when the clutch is engaged.

[0011]

Since the conventional automatic transmission clutch shown in FIG. 7 is provided with a check valve,
It is possible to prevent centrifugal hydraulic pressure from being generated except when pressurizing, but since the O-ring provided on the outer circumference of the piston is constantly in contact with the inner peripheral surface of the cylinder, sliding resistance occurs when the piston moves. In many cases, the oil seal portion is easily deteriorated and the response is delayed.

Further, in the conventional clutch for automatic transmission shown in FIG. 8, since the leak passage is formed on the outer peripheral side of the piston, all the generated centrifugal hydraulic pressure can be leaked, so that the drag of the clutch can be prevented. Since the O-ring provided in the groove on the outer circumference of the piston, that is, the oil seal portion and the inner wall of the cylinder are in constant contact with each other, sliding resistance occurs when the piston moves, and the oil seal There were often problems such as easy deterioration of parts.

The present invention has been made in view of the above circumstances, and the automatic gear shift which is capable of extending the life of the oil seal portion formed between the outer circumference of the piston and the inner circumference of the cylinder and is excellent in responsiveness. The purpose is to provide a machine clutch.

[0014]

As a means for solving the above-mentioned problems, the invention according to claim 1 is as follows.
A piston housed inside the cylinder so that it can move back and forth,
In an automatic transmission clutch that advances by supplying hydraulic pressure to an oil chamber in a cylinder to engage a friction plate arranged in front of the piston, an inner peripheral surface of the cylinder and an outer peripheral surface of the piston are A seal portion, which is in a non-contact state with each other and has a gap formed between the inner and outer peripheral surfaces thereof, and which abuts each other when the piston advances by a predetermined amount or more to seal the gap in a liquid-tight state, is provided in the cylinder. It is characterized in that it is provided on the inner peripheral surface and the outer peripheral surface of the piston.

Therefore, in the present invention, since the piston is not in contact with the cylinder on its outer peripheral surface, the life of the oil seal function can be extended and the sliding resistance at this portion is eliminated, so that the responsiveness of the clutch is improved. Is improved.

Further, when the piston is in the retracted state, the gap between the inner and outer peripheral surfaces of the piston and the cylinder functions as a leak passage to connect the oil chamber and the discharge portion in front of the piston. Since the oil remaining in the oil chamber is discharged from this gap to prevent the centrifugal hydraulic pressure from being generated, the clutch drag due to the centrifugal hydraulic pressure is prevented. Further, since it is not necessary to provide a check ball for exhaust pressure, the piston can be made thinner, so that the automatic transmission can be made smaller and lighter, and the vehicle mountability of the automatic transmission can be improved. Furthermore, since the piston has a simple structure, it is easy to assemble and maintain the device.

When the piston has moved forward by a predetermined amount or more, the seal portions provided on the inner peripheral surface of the cylinder and the outer peripheral surface of the piston abut each other to liquid-tighten the gap functioning as a leak passage. Since the state is sealed, it is possible to prevent leakage of the oil pressure in the oil chamber and obtain the required engagement pressure.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be specifically described with reference to FIGS.

1 to 3 show an embodiment of an automatic transmission clutch 1 according to the present invention. The automatic transmission clutch 1 is arranged coaxially with an input shaft (not shown) and the shaft. It is used for connecting and disconnecting torque transmission with an output shaft (not shown) that is connected to each other, and both shafts are respectively connected to meshing speed change elements of a gear speed change mechanism (not shown).

The automatic transmission clutch 1 is spline-fitted to the input shaft, and as shown in FIG.
A cylinder-shaped clutch drum 6 integrally formed with a cylinder 5 for accommodating the piston 4 is provided. Inside the clutch drum 6, a plurality of clutch plates 7 having an annular shape similar to a conventional one are provided at the center of the clutch drum 6. It is spline-fitted at the outer periphery so as to be slidable along the axis. The oil check valve is abolished from the piston 4.

Between the clutch plates 7, there is arranged an annular clutch disk 8 which is frictionally engaged by being pressed against each other, as in the conventional case. Each clutch disc 8 is spline-fitted to the clutch hub 9 at its inner edge so that it can slide like the clutch plate 7, and this clutch hub 9 is also spline-fitted to the output shaft. Also,
In the illustrated example, a clutch hub 18 for the next-stage clutch is fixed to the open end of the clutch drum 6 via a snap 10.

The piston 4 also forms an oil chamber 12 on one side thereof together with the cylinder 5. Hydraulic pressure is supplied into the oil chamber 12 from an oil pressure control device (not shown) via an oil supply port (not shown) provided near the outer edge of the cylinder 5. On the other side of the piston 4, attach one end to the piston 4
Is provided, and the other end of the coil spring 14 is brought into contact with the washer 13 arranged in the boss portion 19. The elastic return force of the spring 14 causes the piston 4 to exert a biasing force to the left in FIG. Received and held in the return position. On the other side of the outer edge portion of the piston 4, the clutch plate 7 and the clutch disc 8 are pressed against each other by sliding the piston 4 to the right in FIG.
A pressing portion 15 for frictionally engaging is provided.

As an example, the inner periphery of the cylinder 5 is provided with an annular convex portion 17 in which an elastic body is formed into a substantially triangular cross section along the inner periphery thereof, and the outer periphery of the piston 4 is provided with the clutch drum 6 side. An annular step portion 11 is formed by reducing the outer peripheral radius of the, and a portion where the convex portion 17 and the step portion 11 engage with each other serves as the oil seal portion 2. More specifically, at the engaging portion of the oil seal portion 2, the convex portion 17
Are gradually narrowed toward the outer circumference of the piston, and the step portions 11 are provided at equal slopes so as to be parallel to the side surfaces of the convex portions 17. That is, the step portion 11 corresponds to the contact portion described in the claims.

The oil seal portion 2 has a leak passage 16 for communicating both sides of the piston 4, that is, the oil chamber 12 side and the clutch drum 6 side until the piston 4 is moved forward by a predetermined amount or more to be in a clutch engagement state. Are formed.

The leak passage 16 is provided in the clutch drum 6.
It is formed by forming a gap over the entire circumference between the step portion 11 on the outer peripheral portion of the piston 4 on the side and the convex portion 17 on the inner peripheral portion of the cylinder. That is, except when the piston 4 is engaged, the outer circumference of the piston 4 and the inner circumference of the cylinder 5 are not in contact with each other.

The contact position between the convex portion 17 and the step portion 11 is determined by the clutch plate 7 and the clutch disc 8.
And are configured to be immediately before dragging occurs.

Next, the operation of the automatic transmission clutch 1 configured as described above will be described. When the clutch is not engaged as shown in FIG. When the oil pressure is started to be supplied to the oil chamber 12, the oil pressure causes the piston 4 to be pressed rightward in FIG.
A part of the hydraulic pressure supplied to 2 is leaked from the oil chamber 12 through the leak passage 16.

The amount of hydraulic pressure leaked through the leak passage 16 is an annular step formed on the outer circumference of the piston 4 as the piston 4 moves to the right in FIG. 1 toward the clutch engagement position. When the portion 11 approaches the annular convex portion 17 provided on the inner circumference of the cylinder 5, the effective diameter of the leak passage 16 gradually decreases.

Further, the forward movement of the piston 4 causes the pressing portion 15 to press the clutch plate 7 and the clutch disc 8 to move them to a position where they are completely engaged. At this time, the step portion 1 on the outer circumference of the piston 4
Since 1 and the convex portion 17 on the inner circumference of the cylinder 5 are in close contact with each other and are in an airtight state, the oil seal portion 2 formed by the convex portion 17 and the step portion 11 does not function as the leak passage 16. .

Therefore, as the piston 4 moves forward, that is, from the position shown in FIG. 2A to the position shown in FIG. 2B, the hydraulic pressure acting on the piston 4 is inversely proportional to the amount of oil leak. After gradually increasing to, it stops increasing and becomes a constant value.

Further, even when a relatively high oil pressure is supplied to the oil chamber 12, the leak passage 16 acts as a buffer, so that the oil pressure acting on the piston 4 is gradually increased from a relatively small value. The piston 4 presses the clutch plate 7 and the clutch disc 8 through the pressing portion 15 of the piston 4 to gradually engage the members 7 and 8 with proper slip. By the engagement of both members 7 and 8,
The driving force of the input shaft is the same as the conventional one.
It is transmitted to the output shaft via the clutch plate 7, the clutch disc 8 and the clutch hub 9.

When the oil pressure is not applied to the oil chamber 12, the leak passage 16 is in the open state, so that the oil pressure in the oil chamber 12 is the rotation of the cylinder 5 integral with the input shaft. The oil pressure is guided to the outer peripheral side by the action of the centrifugal force caused by the
2 is led to the outside.

Since the convex portion 17 provided on the inner periphery of the cylinder 5 is made of an elastic body, the impact when the step portion 11 on the outer periphery of the piston 4 comes into contact with the convex portion 17 is absorbed, Contact and contact relatively gently. Further, since the oil pressure in the oil chamber 12 leaks from the oil seal portion 2 that serves as the leak passage 16, the oil pressure and the oil viscosity are
Since it also has an effect of suppressing the approach between the outer circumference of the piston 4 and the inner circumference of the cylinder 5, the impact at the time of contact between the outer circumference of the piston 4 and the inner circumference of the cylinder 5 is absorbed to some extent.

FIG. 3 shows a case where the oil check valve and the oil seal portion are combined without abolishing the oil check valve. In this case, the oil check valve 30 and the oil seal portion 2 leak the centrifugal oil pressure acting on the piston 4 to suppress the increase of the oil pressure due to the centrifugal force and prevent the clutch from dragging.

Further, the oil seal portion 2 serving as the leak passage 16 as described above may be configured as shown in FIGS. 4 to 6, respectively.

That is, FIG. 4 shows an example in which the oil check valve 30 is abolished similarly to the above-described embodiment, in which the outer circumference of the piston 31 has an annular step with a smaller outer radius on the clutch drum side and a right angle in cross section. An annular elastic body 32 having a rectangular cross section is attached to a surface of the stepped portion that is perpendicular to the axis of the piston 31. And piston 3
The cylinder 33 that accommodates the clutch 1 and the clutch drum 34 that accommodates the clutch plate 7 and the like are configured such that their openings are combined with each other, and the cylinder 33 protrudes in the axial direction provided in the opening of the clutch drum 34. The end wall formed is a convex portion 35 that engages with the step portion.

FIG. 5 shows the oil seal portion 2 of FIG. 4 with the elastic body 32 removed. That is, the outer peripheral radius of the piston 31 on the clutch drum side is reduced to form an annular step portion having a right angle in cross section, and the stepped portion and the end wall, that is, the convex portion 35 are brought into contact with each other by the metal surfaces finished by sliding. It is configured to be sealed in a liquid tight state.

Further, in FIG. 6, the elastic body 32 provided in the step portion in FIG. 4 is attached to the end wall provided in the opening of the clutch drum 34 in FIG. It is a thing.

The operation of the oil seal portion shown in FIGS. 4 to 6 is almost the same as the operation and effect of the above embodiment, and the oil seal portion becomes the leak passage 16 when the piston 4 moves forward by a predetermined amount or more. 2 effective diameter is gradually reduced,
It is sealed at the clutch engagement position. Therefore, due to the buffering action similar to that of the leak passage 16 of the above-mentioned embodiment, the clutch plate 7 and the clutch disc 8 are gradually engaged even when the oil chamber 12 is supplied with oil of relatively high pressure, and Oil chamber 12 except when the clutch is engaged
All the oil inside is guided to the outside of the oil chamber 12 by the action of centrifugal force.

Therefore, according to the clutch 1 for an automatic transmission of the present invention, as described above, the oil seal portion 2 formed by the cylinder 5 and the piston 4 substantially moves according to the forward and backward movement of the piston 4. When the oil seal portion 2 is not engaged with the automatic transmission clutch 1, that is, when the piston 4 is not advanced by a predetermined amount or more, the leak passage 16 is formed and the oil chamber 12 is opened. Leakage of a part of the pressurized oil supplied to the inside causes a buffering effect, and even when a relatively high hydraulic pressure is supplied, the piston 4 does not suddenly operate with a large acting force and is gently operated. To activate.

Further, until the piston is advanced by a predetermined amount or more, the oil seal portion 2 forms the leak passage 16, and the hydraulic pressure is guided to the outside of the oil chamber 12 through the leak passage 16, so that it is generated by the rotation. Centrifugal oil pressure can be released,
The centrifugal oil pressure does not change the clutch engagement force, and the clutch does not drag.
Further, in that case, since a gap serving as the leak passage 16 is formed over the entire circumference between the inner circumference of the cylinder 5 and the outer circumference of the piston 4, the inner circumference of the cylinder 5 and the outer circumference of the piston 4 are except when the clutch is engaged. Since there is no contact with and no sliding resistance occurs,
The responsiveness is improved and the life of the oil seal portion 2 can be extended.

Further, it is possible to have a structure having a function of canceling the centrifugal hydraulic pressure without using an oil check valve. Therefore, by eliminating the oil check valve, it is possible to use a complicated mechanism as in the past. The clutch can be prevented from being dragged and the thickness of the piston can be reduced, so that the total length of the A / T can be shortened.

[0043]

As described above, according to the clutch for an automatic transmission of the present invention, the oil seal portion causes a gap over the entire circumference of the piston and the cylinder until the piston is moved forward by a predetermined amount or more, thereby causing a leak. Since it forms a passage,
Except when the clutch is engaged, the outer circumference of the piston and the inner circumference of the cylinder do not come into contact with each other, and sliding resistance is not received. Therefore, the movement of the piston is smooth and the responsiveness is improved.
In addition, the life of the oil seal part can be extended. Further, since the centrifugal hydraulic pressure can be released from the leak passage, the drag of the clutch can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a clutch for an automatic transmission according to the present invention.

FIG. 2 is a schematic view showing a state in which an oil seal portion formed by the outer circumference of the piston and the inner circumference of the cylinder is opened.

FIG. 3 is a schematic view showing a state where the seal portion is engaged.

FIG. 4 is a schematic view showing a released state of an oil seal portion in another example of the clutch for automatic transmission according to the present invention.

FIG. 5 is a schematic view showing a released state of an oil seal portion in still another example of the clutch for automatic transmission according to the present invention.

FIG. 6 is a schematic diagram showing an open state of an oil seal portion in another example of the clutch for automatic transmission according to the present invention.

FIG. 7 is a schematic view showing an example of a conventional automatic transmission clutch.

FIG. 8 is a schematic view showing a leak passage portion in another example of the conventional automatic transmission clutch.

[Explanation of symbols]

 1 clutch for automatic transmission 2 oil seal part 4 piston 5 cylinder 7 clutch plate 8 clutch disc 9, 18 clutch hub 10 snap 11 step part 12 oil chamber 13 washer 14 coil spring 15 pressing part 16 leak passage 17 convex part 19 boss part

Claims (1)

[Claims] 1. An automatic transmission in which a piston housed in a cylinder so as to be movable back and forth is moved forward by supplying hydraulic pressure to an oil chamber in the cylinder to engage a friction plate arranged in front of the piston. In a machine clutch, the inner peripheral surface of the cylinder and the outer peripheral surface of the piston are brought into non-contact with each other to form a gap between these inner and outer peripheral surfaces, and when the piston moves forward by a predetermined amount or more, A clutch for an automatic transmission, characterized in that a seal portion that abuts and seals the gap in a liquid-tight state is provided on an inner peripheral surface of the cylinder and an outer peripheral surface of the piston.