JPH0130660Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to the improvement of a hydraulic servo device for an automatic transmission, particularly a brake device that controls a part of shift control of an automatic transmission.

BACKGROUND TECHNOLOGY Some automatic transmissions are composed of a fluid clutch or a torque converter, a planetary gear device, a speed change control device, etc., but the speed change control device for this transmission is a rotary motion extracted from the engine via the torque converter. The gear ratio is controlled when the gear is shifted to a predetermined ratio using a planetary gear and taken out from the output shaft.

That is, the speed change control device includes a plurality of frictional engagement means such as clutches and brakes, and controls the speed of the output shaft of the planetary gear by a combination of ON and OFF (intermittent) of these frictional engagement means.

The piston, which is a hydraulic servo piston that constitutes a conventional speed change control device, is attached to an intermediate shaft (or input/output shaft) relative to the cylinder part of a center support fixed to a transmission case, for example.
It is housed so that it can slide freely in any direction, and is controlled ON-OFF by hydraulic pressure from a shift valve (not shown).

This piston is formed into an annular shape centered on the intermediate axis, and high-rigidity parts and low-rigidity parts are connected alternately, for example, in three places to form an annular shape, and the high-rigidity part uses its projections to create friction. The other low-rigidity portion serves as a recess for storing a return spring.

However, because conventional pistons have low overall rigidity, the piston itself is easily deformed by the pushing force during assembly and hydraulic pressure during operation, resulting in poor sliding in the cylinder part and O-ring part (seal part). Hydraulic pressure leaks from the brake, and sufficient braking action is not achieved.

On the other hand, if the piston's thin-walled parts are made thicker in order to sufficiently increase the rigidity of the piston, the piston as a whole will become thicker and the originally thicker parts will be thicker than necessary. Since the machine is constructed so that the oil supply passages to each part and the piston are close to each other in the front and back, if the piston is made thicker, the oil supply passage must be shifted accordingly, which reduces the axial dimension of the entire transmission. There is a problem with getting bigger.

The basic purpose of this invention is to solve such problems, and without changing the basic oil path configuration that supplies oil to various parts, it increases the rigidity of the hydraulic servo piston, especially the brake piston, and prevents deformation. The purpose is to prevent malfunction of the frictional engagement device.

In accordance with the basic purpose, the present applicant has filed a parallel application with the present application (filed on the same day, the name of the device is "Hydraulic servo piston device for automatic transmission"), in which a protrusion that presses a friction engagement member against the front end surface of the piston and a piston. Recesses for storing return springs are alternately arranged in an annular shape, and reinforcing protrusions are provided on the rear end surface of the piston at positions corresponding to the back surfaces of the recesses that protrude toward the bottom surface of the cylinder part, and the cylinder faces the protrusions. A brake device for an automatic transmission is disclosed that has a recessed portion on the bottom surface into which a protrusion is inserted.

Problems to be Solved by the Invention Since the piston of the brake device disclosed in the above-mentioned parallel application is not provided with any rotation prevention mechanism with respect to the central axis of the transmission, as the piston operates over and over again, There is a risk that it will rotate around the As the piston rotates, the side surface of the protrusion eventually comes into contact with the side surface of the recess in the hydraulic chamber of the cylinder, and the hydraulic chamber becomes separated.
If the oil pressure from the oil passage is applied to the chamber in this condition, the oil in the chamber will not circulate properly, and the oil pressure will act only on the chamber that communicates with the oil passage, causing the piston to tilt, causing the sliding part between it and the cylinder to engage. This may cause malfunction, such as the piston not working. In order to eliminate this possibility, it is conceivable to provide a chamber recess all the way around the bottom of the cylinder part, but if this is done, the chamber volume will become too large, and when oil enters from the oil path, Problems arise such as the time it takes to fill up with oil, the time lag during manual gear shifting becoming longer, or the shift feeling becoming worse. It is also conceivable to provide oil passages for each divided chamber, but this method increases the number of oil passages and creates a new problem of complicating the structure.

The present invention has been made in order to comply with the above-mentioned basic purpose and to solve the various problems that arise from the above.Although it has a simple structure, the chamber is not separated even when the piston rotates, and the oil communication is maintained. The purpose of the present invention is to provide a hydraulic servo device for an automatic transmission that ensures the following.

Means for Solving the Problems The hydraulic servo device for an automatic transmission according to the present invention has the following features:
In a hydraulic servo device for an automatic transmission, the hydraulic servo device for an automatic transmission includes an annular hydraulic servo piston that slides in the axial direction in accordance with hydraulic pressure with respect to a cylinder portion arranged in the axial direction within the transmission case. Axial reinforcing protrusions are provided on the rear end surface of the piston corresponding to the friction engagement member pressing protrusions and the recesses for accommodating return springs arranged alternately in the circumferential direction on the surface, and the cylinder faces the protrusions. In addition to providing a recess for inserting the protrusion into the bottom surface of the part,
The present invention is characterized in that an oil passage is provided in the projection of the piston or the recess of the cylinder portion, through which pressure oil can flow between the contact surfaces when the recess and the projection abut in the circumferential direction.

Structure and operation of the invention As an example of a hydraulic servo device, particularly a brake device, according to the invention, a cylinder portion having an axis line in the direction of the output shaft is formed in an annular shape on the front outer periphery of a center support fixed to a transmission case. An annular piston that slides in the direction of the output shaft according to the working oil pressure is provided for this annular cylinder part, and a protrusion for crimping the brake disc and a recess for housing the return spring of the piston are provided on the front end surface of the piston. Reinforcing protrusions are provided alternately in an annular shape and protrude toward the bottom surface of the cylinder portion at positions corresponding to the back surface of the recessed portion on the rear end surface of the piston.

A recess into which the protrusion is inserted is provided on the bottom surface of the cylinder, and an oil passage is provided in the protrusion of the piston or the recess of the cylinder so that the recess and the flat part of the cylinder communicate with each other. The oil passage can be formed by recessing the side surface of the protrusion of the piston that contacts the side surface of the concave portion of the cylinder portion, or by making a part of the side surface of the protrusion further protrude in the circumferential direction. Further, the oil groove can be formed by further expanding or contracting a portion of the side surface of the recessed portion of the cylinder portion while leaving the protrusion of the piston as it is.

Function Pressure oil that flows from the oil passage into the chamber recess of the cylinder part flows into the chamber divided through the oil passage between the side of the protrusion of the piston and the side of the recess of the cylinder part, and flows into the chamber recessed on the rear end of the piston. It acts on the entire circumference and presses the piston in a certain direction of the frictional engagement member.

When the pressure source of the oil passage is cut off and the drain is connected, the piston is moved back by the return spring, and the oil in the chamber flows through the oil passage into the chamber recess, and is further discharged through the oil passage. .

Example 1 An example of the present invention will be described based on the drawings.
FIG. 6 shows the main parts of an automatic transmission to which the present invention is applied.

The rotational force from the torque converter (not shown) is
Power is transmitted from the input shaft 1 via the clutch 2 or 3 to the intermediate shaft 4 or 5, from which it is taken out via the planetary gear 6 or 7 and from the output shaft 8.

A plurality of friction plates 10 are arranged in an annular manner on the outer periphery of the hub 9 that is integral with the intermediate shaft 5, and the outer periphery end of a brake disc 11 that can be press-fitted to the friction plates 10 is fixed to the transmission case 12. It is cantilevered and fixed to the inner periphery of the annular member 13.

A cylinder portion 14a having an axis in the direction of the intermediate shaft (output shaft) is formed in an annular shape on the front outer periphery of the center support 14 which is fixed to the transmission case 12 behind the center support 14. An annular piston 15 is provided which slides in the direction of the intermediate axis depending on the working oil pressure.

On the front end surface of the piston 15, for example, three protrusions 16 for pressing (pressing) the brake disc 11 are provided approximately in the circumferential direction, and one end 17a of the return spring 17 of the piston 15 is inserted between these protrusions 16. For example, six return spring storage holes (recesses) 18 are formed at three locations in the circumferential direction.

On the other hand, on the rear end surface of the piston 15, three protrusions 19 are provided in the circumferential direction at positions corresponding to the back surface of the spring storage hole 18, and project toward the recess 14b of the cylinder portion 14a of the center support 14.

Note that the outer circumference and inner circumference of the piston 15 are
Seal grooves 22, 23 into which rings 20, 21 fit
is provided. The other end 17b of the return spring 17, which fits into the spring storage hole 18, is positioned by a stop ring 24 fixed to the annular member 13.

As an example, FIG. 1 shows a brake piston 15 sliding within a cylinder portion 14a. As described above, the rear end surface of the piston 15 has a protrusion 19, and oil grooves 19b are formed on both end side surfaces 19a of the protrusion 19. As shown in FIG. 2, the oil groove 19b is formed by recessing a portion of the side surfaces 19a at both ends of the projection. Furthermore, an oil passage 19c communicating with the oil groove 19b is provided on the rear end surface of the piston 15 in a portion where the protrusion 19 is not present.

When pressure oil is supplied into the cylinder part 14a from an oil passage (not shown), the oil flows into the recess 1 of the cylinder part 14a.
4b, the oil flows into the oil passage 19c through oil grooves 19b provided on both end side surfaces 19a of the projection 19. The pressure oil that fills the rear end surface of the piston 15 in this manner acts uniformly on the rear end surface of the piston 15, pressing the piston 15 toward the brake disc 11. Due to this hydraulic action, the brake piston slides within the cylinder portion 14a, and the protrusion 16 presses the brake disc 11 to perform a braking action. Conversely, when the hydraulic pressure to the cylinder portion 14a is released, the piston 15 moves toward the cylinder portion 14a by the action of the return spring 17, and the braking action is released.

Embodiment 2 FIGS. 3 and 4 show another embodiment, in which an oil groove is provided on the bottom surface of the cylinder portion to communicate the divided chambers.

The center support 14 has an annular cylinder portion 14.
a is formed, and a recess 14b into which the projection 19 of the piston 15 is inserted is provided on the bottom surface of the cylinder portion 14a. As can be seen in FIG. 4, both end side surfaces 14c of the recessed portion 14b are partially expanded to form oil grooves 14d. In addition, code 28
is an oil passage that supplies pressure oil to the cylinder portion 14a. When pressure oil is supplied from this oil passage 28, the oil flows from the recess 14b to the bottom through the oil groove 14d, filling the chamber.

Example 3 FIG. 5 shows another example, which is basically the same as Example 1.
However, in order to speed up the rotation of the oil, there is an oil passage 19d on the bottom of the protrusion 19 of the piston 15.
is formed.

Effects of the invention As explained above, according to the invention, although the structure is simple, the rigidity of the hydraulic servo piston, especially the brake piston, is increased to prevent malfunction of the friction engagement device due to deformation of the piston, and the cylinder part Since the oil passage that communicates the recess and the bottom surface of the piston is provided in the protrusion of the piston or the recess of the cylinder part, the chamber is not separated even when the piston rotates, and the pressure oil evenly presses the rear end surface of the piston. It is possible to prevent clipping and to minimize time lag. As a result, malfunctions of the frictional engagement device can be greatly reduced as a whole without changing other parts.

[Brief explanation of drawings]

Figure 1 is a rear view of the brake piston according to the present invention, Figure 2 is an enlarged sectional view taken along line A-A in Figure 1, Figure 3 is a plan view of the cylinder section according to the present invention, and Figure 4 is the figure 3. 5 is a rear view of a brake piston according to another embodiment of the present invention, and FIG. 6 is a sectional view of a brake device for an automatic transmission to which the present invention is applied. 14a...Cylinder part, 14b...Recessed part, 14
d...Oil groove, 15...Piston, 19...Protrusion,
19b...Oil groove.

Claims (1)

[Scope of utility model registration request] In a hydraulic servo device for an automatic transmission that includes an annular hydraulic servo piston that slides in the axial direction in accordance with hydraulic pressure with respect to a cylinder portion that is arranged in the axial direction within the transmission case, the front end of the piston Axial reinforcing protrusions are provided on the rear end surface of the piston corresponding to the friction engagement member pressing protrusions and the return spring storage recesses arranged alternately in the circumferential direction on the surface, and the cylinder faces the protrusions. A recess into which the protrusion is inserted is provided on the bottom surface of the part, and an oil passage is provided in the protrusion of the piston or the recess of the cylinder part through which pressure oil can flow between the contact surfaces when the recess and the protrusion abut in the circumferential direction. A hydraulic servo device for an automatic transmission characterized by: