JP3552784B2 - 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

[0001]
[Industrial applications]
The present invention relates to a piston stopper structure for defining a stroke end of a piston incorporated in a side cover of an automatic transmission for driving a multi-plate brake disposed on an outer peripheral portion inside a housing of the automatic transmission.
[0002]
[Prior art]
One type of automatic transmission is one in which a side cover is connected to one end of a housing member that houses a transmission mechanism, and one shaft end of a main shaft is supported by a bearing structure provided on the side cover. . Such a type is adopted in an automatic transmission that does not directly take out the shift output from the shaft end of the main shaft, for example, an FF type automatic transmission that takes out the shift output from an output shaft arranged in parallel with the main shaft.
[0003]
In an automatic transmission having a side cover, (1) an annular hydraulic cylinder surrounding a main shaft is formed on the side cover, (2) a multi-plate brake is disposed on an outer peripheral portion inside a housing member, and (3) a side cover. A configuration is possible in which a multi-plate brake is driven by a piston inserted into a hydraulic cylinder.
According to such a configuration, the arrangement of the oil passage for supplying the hydraulic pressure to the hydraulic cylinder is facilitated as compared with the case where the multi-plate brake is driven using the hydraulic cylinder and the piston which rotate integrally with the main shaft, and the automatic transmission is changed. The overall structure of the machine is simplified.
[0004]
An automatic transmission in which a hydraulic cylinder is provided on a side cover is disclosed, for example, in Japanese Utility Model Laid-Open No. 59-152240. Here, a rear cover (side cover) is attached to one side of a case (housing), and one end of an output shaft (main shaft) is supported by a bearing provided on the rear cover. Further, a multi-plate brake is arranged on an outer peripheral portion in the case, and the multi-plate brake is driven using an annular piston inserted into a hydraulic cylinder of a rear cover.
[0005]
[Problems to be solved by the invention]
In the automatic transmission disclosed in Japanese Utility Model Laid-Open Publication No. 59-152240, a stroke end is set to a maximum extent on the rear cover side of the piston while the piston is abutted against a projection formed on the bottom of the hydraulic cylinder. I have. 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, (1) the projections hinder the cylinder surface inside and outside of the hydraulic cylinder from being machined sufficiently to the bottom, and (2) the shape and height of the projections are finished. The degree of freedom in processing the entire side cover, such as difficulty in processing, decreases the processing cost.
[0006]
Further, at the moment when the hydraulic pressure is supplied to the hydraulic cylinder, the portion in contact with 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 in which the hydraulic pressure is supplied to the hydraulic cylinder, the interval between the piston and the piston is narrow, so that the protrusion of the piston stopper structure hinders the flow of oil, and the rise of the driving force of the piston is easily delayed. Furthermore, since the piston and the projection are in contact with each other while immersed in the piston oil, sticking or sticking occurs when the oil is left for a long time using poor oil. Accordingly, the operation start and operation speed of the piston tend to fluctuate, and are easily affected by the temperature and pressure of the oil. As a result, there is a possibility that the shift operation timing of the automatic transmission is shifted and a shift shock is generated.
[0007]
In addition, the piston can only be retracted from the bottom of the hydraulic cylinder to the position where it is lifted by the height of the projection, and in order to ensure oil flow and wrap around when the piston is retracted, the recesses and grooves around the projection are Since the depth needs to be increased, the thickness of the side cover increases and the weight also increases. Further, the overall axial length of the multi-plate brake mechanism increases, which makes it difficult to reduce the size of the automatic transmission.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a piston stopper structure that 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]
[Means for Solving the Problems]
The invention of claim 1 is connected to the housing of the automatic transmission is formed an annular hydraulic cylinder surrounding the main shaft side cover for supporting one end of the main shaft, multi disposed at the periphery of the said casing An annular piston for driving a plate brake is inserted into the hydraulic cylinder, and the piston provided on the side cover is brought into contact with the abutting portion provided on the piston and the abutting portion provided on the side cover. In the piston stopper structure that determines the position where the piston is retracted to the maximum, the abutting portion of the side cover is disposed on an annular surface located outside the outer cylinder surface of the hydraulic cylinder, the department, the at extended portion from the hydraulic cylinder to the multi-plate brake side, the stepped shape portion of smaller diameter than the outer circumference of the extended portion to the multiple disc brake side shoulder To, and is formed to face in the axial direction with respect to the abutting portion of the side cover.
[0010]
According to a second aspect of the present invention, in the configuration of the first aspect, 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 .
[0011]
[Action]
In the piston stopper structure according to the first aspect, the abutting portion that determines the stroke end of the piston is not disposed in the hydraulic cylinder. The abutting portion of the side cover is set to a surface that intersects 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 piston abuts against the abutment on the side cover, the piston does not contact the bottom of the hydraulic cylinder, and the entire pressure receiving surface of the piston is held in a hollow state. Contact oil. Therefore, when the hydraulic pressure is supplied to the hydraulic cylinder, the entire pressure receiving surface of the piston receives the pressure immediately.
[0012]
In the piston stopper structure according to the second aspect, the high-pressure oil that has flowed into the hydraulic cylinder while the piston is 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. Enhance.
[0013]
【Example】
A multi-disc brake mechanism according to a first embodiment will be described with reference to FIGS. FIG. 1 is a sectional view of a multiple disc brake mechanism according to a first embodiment, and FIG. 2 is an explanatory view of the overall structure of an FF type automatic transmission.
In FIG. 1, (a) is a cross-sectional view of a side cover portion of the automatic transmission shown in cross-section along a main shaft, and (b) is a partially enlarged view of (a).
[0014]
In FIG. 1A, one end of a main shaft 11 of the automatic transmission arranged on the center line is supported by a bearing structure provided on a side cover 12.
The side cover 12 is connected to the transmission case 13 by a number of bolts 14 arranged along the outer edge of the side cover 12.
An annular hydraulic cylinder 19 surrounding the center line of the main shaft 11 is formed on the side cover 12. An annular piston 15 is inserted into the hydraulic cylinder 19, and the piston 15 is movable in the axial direction.
[0015]
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 drawing. On the other hand, when the hydraulic pressure of the hydraulic cylinder 19 is released, the restoring force of the return spring causes the piston 15 to move leftward in the drawing, and is drawn into the hydraulic cylinder 19 to a position limited by a piston stopper structure described later.
The piston 15 presses the overlap between the driven plate 17 and the drive plate 16 arranged on the outer peripheral portion inside the transmission case 13 to generate a frictional force on the opposing surfaces of the driven plate 17 and the drive plate 16.
[0016]
The retaining plate 18 and the driven plate 17 are restrained by splines 13 </ b> A formed in the transmission case 13 and are held so as not to rotate with respect to the transmission case 13. The axial position of the retaining plate 18 is limited by the snap ring 18S.
The drive plates 16 alternately arranged with the driven plates 17 do not mesh with the splines 13A of the transmission case 13, but are positioned rotatably with respect to the transmission case 13 with the outer periphery positioned closer to the center than the splines 13A. You. The inner peripheral portion of the drive plate 16 meshes with a spline formed on an inner member indicated by a broken line, and the drive plate 16 rotates integrally with the inner member.
[0017]
In the multi-plate brake mechanism of the first embodiment, when high-pressure oil flows into the hydraulic cylinder 19 and is supplied with hydraulic pressure, the piston 15 driven by the hydraulic pressure moves rightward in the axial direction in the drawing, and The driven plate 17 and the drive plate 16 are sandwiched between the 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 from rotating with respect to the transmission case 13.
On the other hand, when the hydraulic pressure of the hydraulic cylinder 19 is released, the piston 15 is driven by the above-mentioned return spring and retreats toward the side cover 12. 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 the restraint from the driven plate 17 and can rotate with respect to the transmission case 13 again.
[0018]
FIG. 1B shows a state where the piston 15 is slightly moved from the state of FIG.
In the multi-plate brake mechanism of the first embodiment, a piston stopper structure that determines a position where the piston 15 is fully retracted toward the side cover 12 is disposed outside the hydraulic cylinder 19. An abutment surface 20 perpendicular to the center line of the main shaft 11 is provided on the top of the cylinder wall outside the annular hydraulic cylinder 19 formed on the side cover 12.
[0019]
On the other hand, the piston 15 has a contact surface 21 perpendicular to the center line of the main shaft 11 corresponding to the contact surface 20 as shown in FIG. When the piston 15 is driven by the above-described return spring and the abutment surface 21 abuts against the abutment 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) position of the abutment surfaces 20, 21 is set so that such a retracted state of the piston 15 is obtained.
In addition, depressions 15L and 19L are formed on both the bottom surface of the hydraulic cylinder 19 and the pressure receiving surface of the piston 15 so as to smoothly flow in and out of the oil and the flow of dispersion and concentration so as to correspond to the entire circumference of the hydraulic cylinder 19.
When the hydraulic pressure is supplied to the hydraulic cylinder 19 while the piston 15 is retracted and the abutting surfaces 20 and 21 are abutted, the hydraulic cylinder 19 is guided by the depressions 15L and 19L and spreads to all corners of the hydraulic cylinder 19, and enters the hydraulic cylinder 19. The entire pressure receiving surface of the piston 15 located immediately receives the hydraulic pressure.
[0020]
FIG. 2 shows the entire automatic transmission as viewed from above. Here, a so-called FF type automatic transmission is shown.
The casing 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 connecting the side cover 12 to the right side in the figure.
[0021]
Converter housing 35 houses torque converter 36. The transmission case 13 houses a multi-plate brake including the drive plate 16 and the driven plate 17 and other transmission mechanisms 31. The side cover 12 rotatably supports one end of the main shaft 11. Note that the main shaft 11 has two parts that can be relatively rotated. One part is an input shaft of the transmission mechanism 31 that rotates integrally with the output shaft of the torque converter 36, and the other part is an output shaft of the transmission mechanism 31.
The rotation of the main shaft 11 (the output shaft of the transmission mechanism 31) is transmitted to the output shaft 33 via the intermediate shaft 32, and transmitted to wheels (not shown) through the output shaft 33. The output shaft 33 is provided with a differential mechanism 34 for balancing the rotational speeds of the left and right wheels.
[0022]
According to the multi-plate brake mechanism of the first embodiment, since the protrusion 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. Also, since the bottom surface of the hydraulic cylinder 19 is annular and processing in the radial direction is unnecessary, the processing time of the side cover 12 is reduced, and the processing cost is reduced.
Also, as compared with 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 flow of oil set between the bottom of the hydraulic cylinder 19 and the piston 15 is ensured. Therefore, the length of the side cover 12 in the axial direction can be short, and the entire automatic transmission can be downsized accordingly.
[0023]
In addition, the protrusion provided on the bottom surface of the hydraulic cylinder 19 does not hinder the flow of oil, and the entire pressure receiving surface of the piston 15 is in contact with the oil from the beginning of driving, so that the driving force of the piston 15 rises quickly. As a result, 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 unexpected shift shock due to a temporal variation in the operation of the multiple disc brake mechanism.
[0024]
Further, since the depressions 15L and 19L are formed in both the hydraulic cylinder 19 and the piston 15, the weight of the piston 15 and the side cover 12 is reduced by the volume of the depressions 15L and 19L. The mass of the piston 15 decreases, and the movement becomes quick.
In addition, the fluidity of the oil in the hydraulic cylinder 19 is enhanced by the recesses 15L and 19L, so that the oil can be easily dispersed and concentrated compared to the case where a projection having a piston stopper structure is provided at the bottom of the hydraulic cylinder 19. In addition, the operation response of the piston 15 to ON / OFF of the hydraulic pressure supply is enhanced.
[0025]
Further, since the bottom surface of the hydraulic cylinder 19 and the piston 15 are not in contact with each other in a state where the piston 15 is retracted, there is no fear that the bottom surface of the hydraulic cylinder 19 and the piston 15 may stick or stick.
[0026]
Further, since the surface of the piston 15 on the side cover 12 side is stepped and the abutment surface 21 is formed on the shoulder thereof, the retracted position of the piston 15 can be precisely adjusted by cutting the abutment surface 21.
In addition, even if the piston 15 is formed in a stepped shape, the axial length of the piston 15 is not affected. On the other hand, the axial length of the side cover 12 can be shortened. By utilizing this, the axial length of the automatic transmission can be reduced.
[0027]
FIG. 3 is a sectional view of a multiple disc brake mechanism according to the second embodiment. In the second embodiment, a slight design change is added to the piston 15 of the first embodiment, and the other parts are the same as those of the first embodiment. FIG. 3 shows a portion related to this change corresponding to FIG. Members common to those in the first embodiment are denoted by the same reference numerals as in FIG. 1, and detailed description thereof is omitted.
[0028]
The side cover 12 and the transmission case 13 are the same as in the first embodiment. The side cover 12 is connected to an end of the transmission case 13 by inserting a spigot portion 12E. The spigot portion 12E is an annular protrusion, and by inserting the spigot portion 12E into the end of the transmission case 12, the mechanism on the side cover 12 side, such as the piston 15B, is positioned (centered) on the mechanism on the transmission case 13 side. You.
[0029]
In the multi-plate brake mechanism of the second embodiment, the top surface of the spigot portion 12E is used as a piston stopper structure that determines a position where the piston 15B is drawn to the side cover 12 to the maximum. An annular surface at the top of the spigot portion 12E is defined as an abutment surface 20B on the side cover 12 side, and an abutment surface 21B is provided on an annular protrusion 15D formed on the outer periphery of the piston 15B.
In a state in which the piston 15B retreats to the side cover 12 to the maximum and the piston 15B abuts against the abutment surface 20B of the side cover 12, the piston 15B comes from the bottom of the hydraulic cylinder 19 as in the first embodiment. The pressure receiving surface of the piston 15B is located at a position slightly apart.
When 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.
[0030]
According to the multiple disc brake mechanism of the second embodiment, the abutment surface can be machined simultaneously with the finishing of the spigot portion 12E. Basically, the same effect as in the first embodiment can be obtained only by employing the piston 15B.
[0031]
【The invention's effect】
According to the first aspect of the present invention, since the protrusion of the piston stopper structure is not provided at the bottom of the hydraulic cylinder, the length of the side cover in the axial direction can be saved correspondingly, and the automatic transmission can be downsized.
In addition, since the protrusion of the piston stopper structure does not obstruct the oil flow, the oil around the oil in the hydraulic cylinder becomes smooth, and the entire pressure receiving surface of the piston receives oil pressure from the beginning, so the movement of the piston is smooth and quick. And the operation of the multi-plate brake mechanism is assured. The operating speed of the piston can also be precisely adjusted.
[0032]
According to the second aspect of the present invention, the flow of the oil in the hydraulic cylinder becomes smooth, and the operation response of the piston to the supply of the hydraulic pressure increases.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multiple disc brake mechanism showing a first embodiment.
FIG. 2 is an explanatory diagram of the entire structure of the automatic transmission.
FIG. 3 is an explanatory diagram of a multiple disc brake mechanism according to a second embodiment.
[Explanation of symbols]
11 Main shaft 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 Abutment surface 32 Intermediate shaft 33 Output shaft 34 Differential mechanism 35 Converter housing 36 Torque Converter 13A Spline 15D Annular projection 18S Snap ring 15L, 19L recess

Claims (2)

An annular hydraulic cylinder surrounding the main shaft is formed on a side cover that is connected to a housing of the automatic transmission and supports one end of the main shaft,
It said annular piston for driving the arranged multi-plate brake to the outer peripheral portion of the housing is inserted into the hydraulic cylinder,
In a piston stopper structure for determining a position where the piston is maximally retreated toward the side cover in a state where the abutting portion provided on the piston and the abutting portion provided on the side cover abut against each other. ,
The abutting portion of the side cover is disposed on an annular surface located outside the outer cylinder surface of the hydraulic cylinder,
The abutting portion of the piston is a portion extended from the hydraulic cylinder to the multi-disc brake side, and a shoulder of a step-shaped portion having a smaller diameter than the outer periphery of the portion extended to the multi-disc brake side , A piston stopper structure formed so as to be axially opposed to the abutting portion of the side cover. 2. The piston stopper structure according to claim 1 , wherein an annular groove is formed around at least one of the bottom surface of the hydraulic cylinder and the facing surface of the piston.

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