JPH08277859A - Piston stopper structure - Google Patents

Abstract

PURPOSE: To provide piston stopper structure dispensing with complicated protrusions provided at the bottom part of a hydraulic cylinder so as to shorten the axial length of an automatic transmission by that part. CONSTITUTION: The abutting face 20 of a side cover 12 is provided at the shoulder part of an inlet on the cylinder on the outside of a hydraulic cylinder 19. The abutting face 21 of a piston 15 is provided opposedly to the abutting face 20. The piston 15 can retreat onto the side cover 12 side into an axial position where the abutting face 21 butts the abutting face 20. Annular recess is formed at the pressure receiving face of the piston 15 and the bottom part of the hydraulic cylinder 19 so as to smooth oil flow. When oil pressure is supplied to the hydraulic cylinder 19, the whole pressure receiving face of the piston 15 is driven immediately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention defines a stroke end of a piston incorporated in a side cover of an automatic transmission for driving a multi-disc brake arranged on an inner peripheral portion of a housing of the automatic transmission. The present invention relates to a piston stopper structure.

[0002]

2. Description of the Related Art One type of automatic transmission has a side cover connected to one end of a housing member that houses a transmission mechanism.
The bearing structure provided on the side cover supports one shaft end of the main shaft. Such a type is an automatic transmission that does not directly output the shift output from the shaft end of the main shaft,
For example, it is used in an FF type automatic transmission that takes out a shift output from an output shaft arranged in parallel with a main shaft.

In an automatic transmission having a side cover,
(1) An annular hydraulic cylinder that surrounds the main shaft is formed on the side cover, (2) a multi-plate brake is arranged on the inner peripheral portion of the housing member, and (3) a piston inserted in the hydraulic cylinder of the side cover is used. A configuration for driving the plate brake is possible. With such a configuration, it becomes easier to arrange the oil passages that supply the hydraulic pressure to the hydraulic cylinders, compared to the case where the multiple disc brakes are driven using the hydraulic cylinders and pistons that rotate integrally with the main shaft, and the automatic transmission The overall structure of the machine is simplified.

An automatic transmission in which a side cover is provided with a hydraulic cylinder is disclosed in, for example, Japanese Utility Model Laid-Open No. 59-152240. Here, a rear cover (side cover) is attached to one side of the case (housing), and one end of the output shaft (main shaft) is supported by a bearing provided on the rear cover. A multi-disc brake is arranged on the outer peripheral portion of the case, and the multi-disc brake is driven by using an annular piston inserted in a hydraulic cylinder of the rear cover.

[0005]

[Problems to be solved by the invention]
In the automatic transmission disclosed in Japanese Patent Publication No. 40, in a state where a piston is abutted on a protrusion formed on the bottom of a hydraulic cylinder,
The stroke end is set on the rear cover side of the piston to the maximum extent. That is, the piston stopper structure is arranged in the hydraulic cylinder. For this reason, the structure of the bottom of the hydraulic cylinder becomes complicated, and (1) the protrusions obstruct the cylinder surface inside and outside the hydraulic cylinder to the bottom, and (2) finish the shape and top height of the protrusion. Since the processing is difficult, the degree of freedom in processing the entire side cover is narrowed, and the processing cost increases.

Further, at the moment when the hydraulic pressure is supplied to the hydraulic cylinder, the portion contacting the protrusion of the piston is subtracted from the pressure receiving area, so that the driving force at the start of the operation of the piston is small. Further, in the initial stage when the hydraulic pressure is supplied to the hydraulic cylinder, since the gap between the piston and the piston is small, the protrusion of the piston stopper structure obstructs the oil flow, and the rise of the driving force of the piston is likely to be delayed. Furthermore, since the piston and the protrusion are in contact with each other while immersed in the piston oil,
If poor oil is used and left for a long time, sticking or sticking will occur. Therefore, the operation start and operation speed of the piston are likely to vary, and are easily affected by the temperature and pressure of the oil. As a result, the timing of the gear shifting operation of the automatic transmission may shift and a gear shifting shock may occur.

Further, the piston can be retracted only up to the position where it is lifted from the bottom of the hydraulic cylinder by the height of the protrusion, and in order to secure the flow and sneaking of the oil when the piston is retracted, there is a depression around the protrusion. Since it is necessary to increase the depth of the groove and the groove, the thickness of the side cover increases and the weight also increases. Furthermore, the overall axial length of the multi-disc brake mechanism becomes large, which makes it difficult to reduce the size of the automatic transmission.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a piston stopper structure which does not require a complicated projection on the bottom of a hydraulic cylinder and can shorten the axial length of the automatic transmission accordingly.

[0009]

According to a first aspect of the invention, an annular hydraulic cylinder that surrounds the main shaft is formed on a side cover that is connected to the housing of the automatic transmission and supports one end of the main shaft. A state in which an annular piston for driving a multi-disc brake arranged on the outer peripheral portion of the is inserted into the hydraulic cylinder and the abutting portion provided on the piston and the abutting portion provided on the side cover are abutted against each other. In the piston stopper structure that determines the position where the piston is retracted to the side of the side cover to the maximum, the abutting portion of the side cover has an annular surface located outside the cylinder surface outside the hydraulic cylinder. The piston abutment portion is axially opposed to the abutment portion of the side cover at a portion extending from the hydraulic cylinder to the multi-disc brake side. It was those that are arranged.

According to a second aspect of the present invention, in the configuration of the first aspect, the side cover is formed in such a manner that an annular protrusion formed on the side cover is inserted into an annular recess formed in the casing. Connected to the body, the abutting portion of the side cover is arranged on the top of the annular protrusion.

According to a third aspect of the present invention, in the structure according to the first or second aspect, an annular groove is formed around at least one of the opposed surfaces of the bottom of the hydraulic cylinder and the piston so as to make a circle around the opposed surface.

[0012]

In the piston stopper structure according to the first aspect of the present invention, the abutting portion that defines the stroke end of the piston is not arranged in the hydraulic cylinder. The abutting portion of the side cover is set to a surface intersecting with the center line of the main shaft provided outside the hydraulic cylinder, for example, a surface perpendicular to the center line or a conical surface around the center line. In the stroke end state where the abutting part of the side cover abuts the abutting part of the piston, the piston is not in contact with the bottom of the hydraulic cylinder and the entire pressure receiving surface of the piston is held hollow, Contact with oil. Therefore, when the hydraulic pressure is supplied to the hydraulic cylinder, the entire pressure receiving surface of the piston immediately receives the pressure.

In the piston stopper structure according to claim 2,
By inserting the annular protrusion formed on the side cover into the end portion of the housing member, the side cover and the housing are connected in a so-called "inlay" type. The top of the annular protrusion of the side cover constitutes an annular surface perpendicular to the central axis, and the stroke end is defined by abutting the abutting portion of the piston on this annular surface.

In the piston stopper structure according to claim 3,
The high-pressure oil that has flowed into the hydraulic cylinder with the piston retracted is guided by the annular groove and quickly spreads over the entire pressure receiving surface of the piston, thereby rapidly increasing the driving force of the piston.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-disc brake mechanism of the first embodiment will be described with reference to FIGS. FIG. 1 is a sectional view of a multi-disc brake mechanism of the first embodiment, and FIG. 2 is an explanatory view of the entire structure of an FF type automatic transmission. In FIG. 1, (a) is a sectional view of a side cover portion of an automatic transmission, which is shown in a sectional view along a main axis, and (b) is a partially enlarged view of (a).

In FIG. 1A, one end of the main shaft 11 of the automatic transmission arranged on the center line is supported by the bearing structure provided on the side cover 12. The side cover 12 is connected to the transmission case 13 by a large number of bolts 14 arranged along the outer edge of the side cover 12. The side cover 12 has a spindle 1
An annular hydraulic cylinder 19 is formed that surrounds the center line of 1. An annular piston 15 is inserted in the hydraulic cylinder 19, and the piston 15 is movable in the axial direction.

The piston 15 is biased toward the side cover 12 by a return spring (not shown), and when hydraulic pressure is supplied to the hydraulic cylinder 19, the piston 15 is compressed and moved to the right in the figure. On the other hand, when the hydraulic pressure of the hydraulic cylinder 19 is released, the restoring force of the return spring moves the piston 15 to the left in the drawing, and the piston 15 is drawn into the hydraulic cylinder 19 to a position limited by the piston stopper structure described later. The piston 15 is the transmission case 1
Driven plate 17 arranged on the outer periphery of the inside of 3
By pressing the overlapping of the drive plate 16 with the drive plate 16, a frictional force is generated on the opposing surfaces of the driven plate 17 and the drive plate 16.

The retaining plate 18 and the driven plate 17 are constrained by the splines 13A formed on the transmission case 13 and held nonrotatably with respect to the transmission case 13.
The axial position of the retaining plate 18 is limited by the snap ring 18S. Drive plates 16 alternately arranged with driven plates 17
Is the spline 13A of the transmission case 13.
Are not meshed with each other and are rotatably held with respect to the transmission case 13 by positioning the outer periphery on the center side of the spline 13A. In addition, drive plate 1
The inner peripheral portion of 6 meshes with a spline formed on the inner member indicated by the broken line, and the drive plate 16 rotates integrally with this inner member.

In the multi-plate brake mechanism of the first embodiment, when high-pressure oil flows into the hydraulic cylinder 19 and hydraulic pressure is supplied, the hydraulically driven piston 15 moves to the right in the axial direction, The driven plate 17 and the drive plate 16 are sandwiched between the retainer plate 18 and the retainer plate 18 and compressed. As a result, a frictional force is generated on the opposing surfaces of the driven plate 17 and the drive plate 16, and the drive plate 16 is restrained by the driven plate 17 and locked in rotation with respect to the transmission case 13. On the other hand, when the hydraulic pressure of the hydraulic cylinder 19 is released, the piston 1 is driven by the return spring described above.
5 retreats to the side cover 12 side. Then, the pressure on the opposing surfaces of the driven plate 17 and the drive plate 16 is lost and the mutual frictional force disappears. As a result, the drive plate 16 escapes from the restraint from the driven plate 17 and can rotate again with respect to the transmission case 13.

In FIG. 1B, the piston 15 is shown in FIG.
A state is shown in which the state is slightly moved to the right side in the figure from the state.
In the multi-plate brake mechanism of the first embodiment, a piston stopper structure that determines the position where the piston 15 is pulled to the side cover 12 side to the maximum is arranged outside the hydraulic cylinder 19. At the top of the cylinder wall outside the annular hydraulic cylinder 19 formed on the side cover 12,
An abutting surface 20 perpendicular to the center line of the main shaft 11 is provided.

On the other hand, the piston 15 is formed with an abutting surface 21 corresponding to the abutting surface 20 and perpendicular to the center line of the main shaft 11, as shown in FIG. When the piston 15 is driven by the above-mentioned return spring and the abutting surface 21 abuts the abutting surface 20 of the side cover 12,
The pressure receiving surface of the piston 15 is located at a position slightly away from the bottom surface of the hydraulic cylinder 19. In other words, the height (axial direction) positions of the abutting surfaces 20, 21 are set so that such a retracted state of the piston 15 can be obtained. Further, on both the bottom surface of the hydraulic cylinder 19 and the pressure receiving surface of the piston 15, recesses 15L and 19L for smoothing the flow of oil in and out and the flow of concentrated dispersion are formed so as to correspond to the entire circumference of the hydraulic cylinder 19. When the hydraulic pressure is supplied to the hydraulic cylinder 19 with the piston 15 retracted and the abutting surfaces 20 and 21 abutted, the hydraulic cylinder 19 is guided by the depressions 15L and 19L to reach every corner of the hydraulic cylinder 19 and enter the hydraulic cylinder 19. The entire pressure receiving surface of the piston 15 located immediately receives the hydraulic pressure.

FIG. 2 shows the entire automatic transmission viewed from above. Here, a so-called FF type automatic transmission is shown. The housing of the automatic transmission is configured by connecting the converter housing 35 to the left side of the transmission case 13 in the figure and further connecting the side cover 12 to the right side of the figure.

The converter housing 35 houses the torque converter 36. The transmission case 13 includes a drive plate 16 and a driven plate 17.
The multi-disc brake including the above and other transmission mechanisms 31 are stored. The side cover 12 rotatably supports one end of the main shaft 11. The main shaft 11 has two parts that can rotate relative to each other. One part is the torque converter 36
Is an input shaft of the speed change mechanism 31 that rotates integrally with the output shaft of the above, and the remaining part is an output shaft of the speed change mechanism 31. Spindle 1
The rotation of 1 (the output shaft of the speed change mechanism 31) is transmitted to the output shaft 33 via the intermediate shaft 32, and is transmitted to the wheels (not shown) through the output shaft 33. The output shaft 33 includes a differential mechanism 34 for balancing the rotational speeds of the left and right wheels.
Is provided.

According to the multi-plate brake mechanism of the first embodiment,
Since the projection of the piston stopper structure is not formed on the bottom surface of the hydraulic cylinder 19, the inner and outer cylinder surfaces of the hydraulic cylinder 19 can be easily finished to the bottom. Further, since the bottom shape of the hydraulic cylinder 19 is annular and does not require machining in the radial direction, the machining time of the side cover 12 is shortened and the machining cost is low. Further, compared to the case where the protrusion of the piston stopper structure is formed on the bottom surface of the hydraulic cylinder 19, the hydraulic cylinder 19 can be used up to the bottom, and the oil flow set between the bottom of the hydraulic cylinder 19 and the piston 15 can be secured. Since the space for doing so can be small, the axial length of the side cover 12 can be short, and the entire automatic transmission can be downsized accordingly.

Further, the projection provided on the bottom surface of the hydraulic cylinder 19 does not hinder the oil flow, and the piston 15
Since the entire pressure receiving surface of is in contact with the oil from the beginning of driving, the driving force of the piston 15 rises quickly,
The operation of the multi-disc brake mechanism is ensured, and the operation speed and the like can be precisely adjusted. Therefore, it is not necessary to cause an accidental shift shock due to a temporal variation in the operation of the multiple disc brake mechanism.

Further, the hydraulic cylinder 19 and the piston 15
Since the recesses 15L and 19L are formed in both of them, the weight of the piston 15 and the side cover 12 is reduced by the volume of the recesses 15L and 19L. The mass of the piston 15 is reduced and the movement becomes agile. Further, since the fluidity of the oil in the hydraulic cylinder 19 is enhanced by the depressions 15L and 19L, the oil can be easily dispersed and concentrated as compared with the case where the protrusion of the piston stopper structure is provided on the bottom of the hydraulic cylinder 19. , Piston 1 for ON / OFF of hydraulic pressure supply
The motion response of 5 is enhanced.

With the piston 15 retracted,
Since the bottom surface of the hydraulic cylinder 19 and the piston 15 are not in contact with each other, there is no risk of the bottom surface of the hydraulic cylinder 19 and the piston 15 sticking or sticking together.

Further, since the surface of the piston 15 on the side of the side cover 12 is stepped and the abutting surface 21 is formed on the shoulder thereof, the retracting position of the piston 15 is precisely adjusted by shaving the abutting surface 21. it can. Further, even if the piston 15 has a stepped shape, the axial length of the piston 15 is not affected, and on the other hand, the axial length of the side cover 12 can be short.
The axial length of the automatic transmission can be shortened by directly using the drive plate 16 or the like.

FIG. 3 is a sectional view of the multiple disc brake mechanism of the second embodiment. In the second embodiment, the piston 1 of the first embodiment
5, a slight design change is added, and other parts are the same as in the first embodiment. FIG. 3 shows a portion related to this change in correspondence with FIG. The same members as those in the first embodiment are designated by the same reference numerals as those in FIG. 1, and the following detailed description is omitted.

The side cover 12 and the transmission case 13 are the same as in the first embodiment. The side cover 12 is attached to the end of the transmission case 13,
The spigot portion 12E is inserted and connected. Inlay part 1
2E is an annular protrusion, and by inserting the spigot portion 12E into the end portion of the transmission case 12,
The side cover 12 side mechanism such as the piston 15B is positioned (centered) with respect to the transmission case 13 side mechanism.

In the multi-disc brake mechanism of the second embodiment, the top surface of the spigot portion 12E is used as a piston stopper structure that determines the position where the piston 15B is pulled to the side cover 12 side to the maximum extent. Inlay part 12E
The abutment surface 20B on the side cover 12 side is the annular surface on the top of the, and the abutment surface 21B is provided on the annular projection 15D formed on the outer periphery of the piston 15B. In the state where the piston 15B retreats to the side cover 12 side to the maximum and the piston 15B abuts the abutting surface 21B against the abutting surface 20B of the side cover 12, as in the first embodiment, the hydraulic cylinder 19
The pressure receiving surface of the piston 15B is located at a position slightly away from the bottom surface of the piston. When the hydraulic pressure is supplied to the hydraulic cylinder 19 in this state, the entire pressure receiving surface of the piston 15B immediately receives the hydraulic pressure.

According to the multi-plate brake mechanism of the second embodiment,
The abutting surface can be processed simultaneously with the finishing of the spigot portion 12E. Further, basically, the same effect as that of the first embodiment can be obtained only by adopting the piston 15B.

[0033]

According to the invention of claim 1, since the projection of the piston stopper structure is not provided on the bottom of the hydraulic cylinder, the axial length of the side cover is saved accordingly,
The automatic transmission is downsized. In addition, since the protrusion of the piston stopper structure does not obstruct the flow of oil, the oil around the hydraulic cylinder becomes smooth, and the entire pressure receiving surface of the piston receives hydraulic pressure from the beginning, so the piston moves smoothly and quickly. Therefore, the operation of the multi-disc brake mechanism is ensured. The operating speed of the piston can also be adjusted precisely.

According to the second aspect of the present invention, the conventional side cover connected in an insole type can be used as it is, and it can be implemented with only a slight design change of the piston.

According to the third aspect of the invention, the flow of oil in the hydraulic cylinder becomes smooth, and the operational response of the piston to the hydraulic pressure supply is enhanced.

[Brief description of drawings]

FIG. 1 is a sectional view of a multi-plate brake mechanism showing a first embodiment.

FIG. 2 is an explanatory diagram of an overall structure of an automatic transmission.

FIG. 3 is an explanatory diagram of a multiple disc brake mechanism of a second embodiment.

[Explanation of symbols]

 11 Spindle 12 Side Cover 13 Transmission Case 14 Bolt 15,15B Piston 16 Drive Plate 17 Driven Plate 18 Retaining Plate 19 Hydraulic Cylinder 20, 21, 20B, 21B Abutting Surface 32 Intermediate Shaft 33 Output Shaft 34 Differential Mechanism 35 Converter Housing 36 Torque Converter 13A Spline 15D Annular protrusion 18S Snap ring 15L, 19L Recess

Claims (3)

[Claims] 1. A multi-disc brake arranged on an outer peripheral portion of the casing, wherein a side cover connected to a casing of the automatic transmission and supporting one end of the spindle has an annular hydraulic cylinder surrounding the spindle. An annular piston that drives the piston is inserted into the hydraulic cylinder, and the piston is provided on the side of the side cover with the abutting portion provided on the piston and the abutting portion provided on the side cover abutting each other. In the piston stopper structure that determines the position where the piston is maximally withdrawn, the abutting portion of the side cover is arranged on an annular surface located outside the outer cylinder surface of the hydraulic cylinder, and the abutting portion of the piston. Is disposed in a portion extending from the hydraulic cylinder to the multi-plate brake side so as to axially face the abutting portion of the side cover. Piston stopper structure that. 2. The side cover is connected to the housing by inserting an annular protrusion formed in the side cover into an annular recess formed in the housing, and an abutting portion of the side cover. The piston stopper structure according to claim 1, wherein is disposed on the top of the annular protrusion. 3. The piston stopper structure according to claim 1, wherein at least one of the bottom surface of the hydraulic cylinder and the facing surface of the piston is formed with an annular groove that goes around the facing surface.