KR20110030787A - Hydraulic brake - Google Patents

Abstract

PURPOSE: A hydraulic brake is provided to increase the torque capacity of the brake by using the piston unit comprising two pistons within the limited space. CONSTITUTION: A cylinder(230) is formed in a transmission case. A piston unit(220) is installed within the cylinder. The piston unit operates by the operation fluid pressure. An operation plate(260) is pressurized by the operation of the piston unit in axial direction. A friction disc(270) is pressurized as being arranged along with the operation plates alternately.

Description

Hydraulic Brake {HYDRAULIC BRAKE}

The present invention relates to a hydraulic brake for use in an automatic transmission, and more particularly, to reduce the number of friction disks, to reduce the drag torque generated when the brake is inactive, and at the same time improved hydraulic brake assembly It is about.

As is well known, an automatic transmission is a device that automatically shifts to an appropriate shift stage according to a driving state of a vehicle. In order to implement such automatic transmission, the automatic transmission includes a planetary gear set including sun gear, ring gear, and planet carrier as its operating members. and at least one set, and a plurality of friction elements, such as a clutch and a brake, are provided to control the operation of such operating members.

And the automatic transmission is equipped with a hydraulic control system (hydraulic control system) for hydraulically controlling such friction elements. Accordingly, the clutches and the brakes determined according to the shift stages are controlled to be engaged or released by the hydraulic control system, thereby implementing each shift stage.

Among the friction elements, the brake serves to stop or prevent the rotation of the operating member of the planetary gear set that is rotating.

Such brakes are used to stop rotating members in general machines as well as automatic transmissions.

1 is a cross-sectional view showing a hydraulic brake of an automatic transmission according to the prior art. Although the hydraulic brake applied to the automatic transmission is shown for convenience of description, the present invention is not limited thereto and may be applied to a general machine.

As shown in FIG. 1, a hydraulic brake 100 of a conventional automatic transmission is installed in a transmission case 110.

The hydraulic brake 100 is a cylinder 130 formed in the case 110, a piston 120 is operated by the hydraulic pressure is inserted into the cylinder 130 is input, and the piston 120 And a return spring 140 disposed at an opposite position of the cylinder 130 to apply a restoring force to the piston 120.

Sealing members 122 and 124 are interposed between the outer diameter portion and the inner diameter portion of the piston 120 and the cylinder 130, respectively.

The return spring 140 is supported by a spring support 142, and the spring support 142 is fixed to the case 110 by a snap ring 145.

In addition, the brake hub 150 of the automatic transmission includes a plurality of friction disks 170 on its outer circumferential surface in a spline structure, and the case 110 has a plurality of operations. Operating plates 160 are provided on their inner circumferential surface in a splined structure. The friction disks 170 and the operating plates 160 are alternately arranged.

An oil hole 122 and an oil pocket 114 are formed in the case 110 to supply oil to the cylinder 110. In this way, the oil supplied to the cylinder 130 presses the piston 120 to the left in the drawing to overcome the elastic force of the return spring 140 and moves the piston 120 to the left in the drawing.

Thus, the piston 120 presses the actuation plates 160 along the axial direction, such that the actuation plates 160 and the friction discs 170 engage by the friction force between them. . By this process, rotation of the brake hub 150 is stopped.

When the oil supply to the cylinder 130 through the oil hole 112 is stopped, the piston 120 is moved to the right in the drawing by the restoring force of the return spring 140, and thus the operating plates 160 engaged with each other. ) And friction disks 170 are disengaged from their engaged state. Accordingly, the brake hub 150 is in a rotatable state.

However, in the hydraulic brake 100 used in an automatic transmission or the like, oil is applied to the friction disk 170 and the operation plate in order to cool the heat generated by the slip between the operation plate 160 and the friction disk 170 during engagement. 160) to supply continuously.

As is well known, when the brakes are not engaged, the friction disks 170 rotate at an arbitrary speed by the brake hub 150 connected to the planetary gear member, and the operation plates 160 are connected to the transmission case and stopped. have.

However, since the oil supplied for cooling is continuously supplied even when the brake is not engaged, the rotational resistance, that is, the drag torque, is between the friction disks 170 and the operation plates 60 which are in relative rotational motion due to the viscosity of the oil. ) Will occur.

The drag torque accounts for up to 40% of the total power loss of the automatic transmission and is a major cause of reducing the efficiency of the automatic transmission.

In order to reduce the drag torque, it is most desirable to reduce the number of friction disks used, but there is a problem in that it is not possible to secure the torque capacity of the required brake.

In conventional hydraulic brakes, the piston area has to be increased or the number of friction disks has to be increased in order to sufficiently secure the torque capacity of the brake. However, when the installation space of the brake is limited, such as in an automatic transmission, it is difficult to increase the diameter of the piston. Therefore, the torque capacity of the brake has been secured mainly by increasing the number of friction disks, which results in an increase in drag torque. Caused.

In addition, the hydraulic brake of the existing automatic transmission is a press after the operator inserts the piston 120, the return spring 140 and the spring support 142 into the cylinder 130, respectively, in the transmission assembly line. After pressing the return spring support 142, the snap ring 145 is fastened to the case 110, there is a problem that the production cycle of the transmission is long.

The present invention has been made to solve the above problems, install two pistons, but in tandem (tandem) arrangement to ensure the maximum torque capacity in a given installation space, reducing the number of friction disks The purpose is to provide a hydraulic clutch that can be made.

In addition, in order to reduce the assembly time of the hydraulic brake in the transmission assembly line, by supplying a piston module incorporating a piston, a return spring, etc., the operator inserts the piston module into the cylinder and fastens the piston module with a snap ring without using a press. Another purpose is to drastically reduce the assembly time of the transmission.

In order to achieve the above object, the hydraulic brake according to the first embodiment of the present invention is a cylinder formed in a case of a transmission, a piston module installed in the cylinder and operated by operating hydraulic pressure, the shaft by the operation of the piston module Working plates pressurized in a direction; And friction disks which are alternately disposed and pressurized with the operation plates.

The piston module is composed of a first piston, a second piston, a first retainer, a second retainer, and a return spring, each of which may be assembled into one module.

The outer diameter of the first piston is in close contact with the cylinder and the inner diameter of the first piston is in close contact with the inner diameter of the first retainer to reciprocate in the axial direction by operating hydraulic pressure. Sealing members may be provided at the outer diameter portion and the inner diameter portion of the first piston, respectively.

The outer diameter portion of the first piston may include an extension for pressing the operating plate and the friction disk.

The extension part is fixed by the outer diameter part of the second piston and the fixing means, and another outer diameter part of the second piston is in close contact with the outer diameter part of the first retainer.

In addition, the inner diameter of the second piston is in close contact with the second retainer, and the second piston reciprocates together with the first piston by operating hydraulic pressure. Sealing members may be provided between the inner diameter portion of the second piston and the second retainer, and between the outer diameter portion of the second piston and the outer diameter portion of the first retainer, respectively.

The return spring may be disposed in a space formed between the first piston and the first retainer.

The first retainer and the second retainer may be pressurized and assembled by a press or the like, and a flow path for supplying hydraulic pressure to the second piston may be formed.

A sealing member for sealing hydraulic pressure may be installed between the cylinder and the piston module.

After the piston module is inserted into the cylinder, it may be fixed to the case by a snap ring.

The hydraulic brake according to the second embodiment of the present invention includes a cylinder formed in a case of a transmission, a piston module installed in the cylinder and operated by operating hydraulic pressure, and operation plates pressurized in an axial direction by the operation of the piston module; And friction disks that are alternately disposed and pressurized with the actuation plates.

The piston module is composed of a first piston, a second piston, a retainer and a return spring, and each may be assembled into a single module.

The outer diameter portion of the first piston is in close contact with the retainer and the inner diameter portion is in close contact with the inner diameter portion of the cylinder to reciprocate in the axial direction by operating hydraulic pressure. Sealing members may be provided at the outer diameter portion and the inner diameter portion of the first piston, respectively.

An inner diameter portion of the first piston may be provided with an extension part for connecting and fixing with the second piston.

A sealing member may be provided between the extension part and the retainer.

The extension portion of the first piston is fixed by the inner diameter portion and the fixing means of the second piston.

The outer diameter portion of the second piston is in close contact with the retainer, and the second piston reciprocates with the first piston by operating hydraulic pressure.

A sealing member may be provided between the outer diameter portion and the retainer of the second piston.

The second piston may include an extension for pressing the actuation plate and the friction disk.

The return spring may be disposed in a space formed between the second piston and the retainer. The return spring may be secured to the retainer by a snap ring.

The retainer may have a flow path for supplying hydraulic pressure to the second piston.

A sealing member for sealing hydraulic pressure may be installed between the cylinder and the piston module.

After the piston module is inserted into the cylinder, it may be fixed to the case by a snap ring.

According to the present invention, by using a piston module that effectively installs two pistons in a limited space to increase the action of the pistons. The torque capacity of the brakes can be increased without increasing the size of the brakes or the number of friction dacks.

On the other hand, the number of friction disks can be reduced by the increased torque capacity, which reduces the drag torque of the brake. Reduced drag torque increases the efficiency of the automatic transmission, thereby improving the fuel economy of the car.

In addition, the discharge oil pressure of the oil pump can be lowered by the increased torque capacity, thereby increasing the efficiency of the automatic transmission.

On the other hand, according to the present invention, in the transmission assembly line, only the piston module integrated with the piston, the retainer and the return spring is assembled in advance and integrated, so that the production cycle is shortened as compared with the case where the existing parts are separately assembled. have.

Usually two to three hydraulic brakes are used in the automatic transmission, if all of them are modularized, the efficiency of the transmission can be greatly improved, and the production cycle of the automatic transmission can be significantly shortened, thereby reducing the production cost.

On the other hand, in contrast to the existing hydraulic brakes, the piston module of the present invention increases the number of two to three parts, this is because a large number of expensive friction disks and operating plates are deleted, rather it can contribute to the material cost of the transmission.

Hereinafter, with reference to the accompanying drawings, a first embodiment of the present invention will be described in detail.

Figure 2 is a cross-sectional view showing a non-operating state of the hydraulic brake of the automatic transmission according to the first embodiment of the present invention, Figure 3 is a cross-sectional view of a piston module in an embodiment of the present invention.

Although the hydraulic brake according to the embodiments of the present invention has been described to be applied to an automatic transmission for convenience of description, the present invention is not limited thereto and may be applied to a general machine.

As shown in Figure 2, the hydraulic brake 200 of the automatic transmission according to the first embodiment of the present invention is a cylinder 230 formed in the case 210 of the transmission, the cylinder 230 is installed in the operating hydraulic pressure Piston module 220 that is operated by, the operation plate 260 is pressed in the axial direction by the operation of the piston module 220; And friction disks 270 that are alternately disposed and pressurized with the operation plates 160.

The piston module 220 is supported and fixed to the case 210 by a snap ring 241, and the case 210 has an oil hole 212 for supplying hydraulic pressure to the piston module 220. An oil pocket 214 is formed.

A sealing member 218 is provided between the piston module 220 and the case 210 to seal the hydraulic pressure.

When operating hydraulic pressure is supplied to the cylinder 230 through the oil hole 212 and the oil pocket 214, the upper end of the piston module 220 moves to the left in FIG. 2 to operate plates 260 and The friction disks 270 are pressed to stop the brake hub 250 connected to the rotating member in the transmission. (See Fig. 5)

When the supply of hydraulic pressure is stopped, the piston module 220 is restored to its original position by the action of the built-in return spring.

Hereinafter, the structure and operation principle of the piston module 220 will be described in detail with reference to FIG. 3.

The piston module 220 is composed of a first piston 222, a second piston 245, a first retainer 280, a second retainer 290 and a return spring 240, each assembled into one module Is made of.

The outer diameter of the first piston 222 is in close contact with the outer diameter of the cylinder 230 (FIG. 2), and the inner diameter is in close contact with the inner diameter of the first retainer 280, and the first piston 220 is closed. Is reciprocated in the axial direction by the hydraulic pressure supplied to the cylinder (230). Sealing members 223 and 224 may be provided at the outer diameter portion and the inner diameter portion of the first piston 222, respectively.

The outer diameter portion of the first piston 222 is formed with an extension portion 225 for pressing the operating plate 260 and the friction disks 270.

The extension portion 225 is fixed by the outer diameter portion of the second piston 245 and the fixing means 247, and the outer diameter portion of the second piston 245 and the outer diameter portion of the first retainer 280 and Close contact. The fixing means 247 may be a means such as a pin, bolt, caulking, and the like.

The inner diameter portion of the second piston 245 is in close contact with the second retainer 290, and the second piston 245 reciprocates with the first piston 222 by operating hydraulic pressure. Sealing members 292 and 285 between the inner diameter portion of the second piston 245 and the second retainer 290 and between the outer diameter portion of the second piston 245 and the outer diameter portion of the first retainer 280). Each is provided.

The first retainer 280 and the second retainer 290 are pressurized and assembled by a press or the like, and flow paths 284 and 294 for supplying hydraulic pressure to the second piston 245 as shown in FIG. ) May be formed. In addition, the right end of the inner diameter portion of the first retainer 280 is in contact with the inner wall of the cylinder 230 to limit the rightward movement of the piston module 220 in the drawing. (See Figure 2)

As shown in FIG. 3, the return spring 240 may be installed in a space 295 formed between the first piston 222 and the first retainer 280. The return spring 240 may be a disc spring, a multi coil spring, or the like, as well as a coiled wave spring as shown.

After the piston module 220 is inserted into the cylinder 230, the piston module 220 is fixed to the case 230 by the snap ring 241, thereby limiting the leftward movement in the drawing.

2, 3, 4, and 5, the operating oil introduced into the cylinder 230 through the oil hole 216 and the oil pocket 214 may move the first piston 222 to the left in the drawing. The pressure is applied to overcome the repulsive force of the return spring 240 and to press the operating plate 260 and the friction disks 270.

Meanwhile, the working oil also acts on the second piston 245 through the oil passages 284 and 294 formed in the first retainer 280 and the second retainer 290, as shown in FIG. 4. ) Will be pressed to the left in the drawing.

However, since the force acting on the second piston 245 is added to the acting force of the first piston 222 through the fixing means 247, the piston module 220 has a greater force than the actuating plates ( 260 and friction disks 270 are pressed.

When the supply of the operating oil is stopped, the first piston 222 is restored to the original position by the action of the return spring 240, by the fixing means 247 connected to the first piston 222. The first piston 245 is also restored to its original position.

The piston module may be preassembled and delivered by a parts supplier before being supplied to a transmission assembly line. A preferred assembly example of the piston module will be described below (see FIG. 3).

First, the first retainer 280 and the second retainer 290 are press-fitted and assembled through a press or the like.

Thereafter, sealing members 285 and 292 are installed in the first retainer 280 and the second retainer 290, respectively. Thereafter, the second piston 245 is inserted between the first retainer 280 and the second retainer 290.

Thereafter, the return spring 240 is positioned on the second retainer 280 and the first piston 222 in which the sealing members 223 and 224 are pre-installed is replaced with the inner diameter of the first retainer 280 and the second piston ( After inserting the outer diameter portion 245, the fastening means 247 is fastened, the assembly of the piston module 220 is completed.

Typically, in hydraulic brakes, the return spring is assembled by compressing the free height of the spring to give a constant pre-load to the piston, so that a press for pressing the return spring is installed in the transmission assembly line.

In the piston module 220, when assembling the first piston 222, the return spring 240 needs to be compressed and assembled. As a result, a force to repel the right side of the first piston 222 is generated in the drawing. .

However, the first piston 222 is connected to the second piston 245 through the extension portion 225 and the fixing means 247, the right side of the second piston 245 is the second retainer Since it is in close contact with 280, the rightward movement of the second piston 245 and the first piston 222 by the preload of the return spring 240 is limited.

As described above, the piston module 220 according to the present invention is already applied with a preload of the return spring 240 therein during the assembly process, so that the piston module 220 is applied to the cylinder 230 without using a press in the transmission production line. Since only the snap ring 241 is inserted after insertion, the assembly process is simplified, and the assembly time is also greatly reduced, thereby reducing the production cost of the transmission. (See Fig. 4)

In addition, the hydraulic brake according to the present invention uses a piston module that can increase the action force of the piston without expanding the space of the conventional hydraulic brake, thereby increasing the torque capacity without increasing the number of friction disks, or the number of friction disks It is possible to maintain the same torque capacity as conventional hydraulic brakes while reducing the pressure.

Accordingly, it is possible to reduce the drag torque generated when the hydraulic brakes are not engaged, thereby improving the efficiency of the transmission and the fuel efficiency of the vehicle using the same.

Hereinafter, a second embodiment of the present invention will be described in detail with reference to the accompanying drawings.

6 is a cross-sectional view showing a non-operating state of the hydraulic brake of the automatic transmission according to the second embodiment of the present invention, Figure 7 is a cross-sectional view of the piston module in the embodiment of the present invention.

As shown in FIG. 6, the hydraulic brake 300 of the automatic transmission according to the second embodiment of the present invention is installed in the cylinder 330 formed in the case 310 of the transmission, the cylinder 330, and is operated in the hydraulic pressure. Piston module 320 is operated by, the operation plate 360 is pressed in the axial direction by the operation of the piston module 320; And friction disks 370 that are alternately disposed and pressurized with the actuation plates 360.

The piston module 320 is supported and fixed to the case 310 by a snap ring 341, and an oil hole 312 for supplying hydraulic pressure to the piston module 320 is provided in the case 310. And an oil pocket 314 is formed.

A sealing member 318 is provided between the piston module 320 and the case 310 to seal the working hydraulic pressure.

When operating hydraulic pressure is supplied to the cylinder 330 through the oil hole 312 and the oil pocket 314, the piston module 320 generates a force acting to the right in FIG. 6 to operate the plates 360. ) And the friction disks 370 to stop the brake hub 350 connected to the rotating member in the transmission. (See FIG. 9)

When the supply of the hydraulic pressure is stopped, the piston module 320 is restored to its original position by the action of the built-in return spring.

Hereinafter, the structure and operation principle of the piston module 320 will be described in detail with reference to FIG. 7.

The piston module 320 is composed of a first piston 322, a second piston 345, a retainer 380 and a return spring 340, each assembled into a single module.

The inner diameter of the first piston 322 is in close contact with the inner diameter of the cylinder 330 (FIG. 6), and the outer diameter is in close contact with the retainer 380, and is operated by the hydraulic pressure supplied to the cylinder 330. The first piston 322 reciprocates in the axial direction. Sealing members 323 and 324 may be provided at the outer diameter portion and the inner diameter portion of the first piston 322, respectively.

An extension part 325 is formed in the inner diameter portion of the first piston 322 to be connected to the second piston 345. The extension part 325 is fixed by the inner diameter part of the second piston 345 and the fixing means 347, and the fixing means 347 is a means such as a pin, bolt, caulking, or the like. Can be.

In addition, the extension portion 325 of the first piston 322 is in close contact with the inner diameter portion of the retainer 380 and a sealing member 392 between the extension portion 325 and the inner diameter portion of the retainer 380. Is interposed.

The outer diameter portion of the second piston 345 is in close contact with the retainer 380, and the second piston 345 reciprocates with the first piston 322 by operating hydraulic pressure. A sealing member 385 is interposed between the outer diameter portion of the second piston 345 and the retainer 380.

On the other hand, the second piston 345 is formed with a protrusion 375 for pressing the operating plate 360 and the friction disks 370.

As shown in FIG. 8, the retainer 380 may have a flow path 384 for supplying hydraulic pressure to the second piston 345. In addition, the left end of the outer diameter portion of the retainer 380 abuts the inner wall of the cylinder 330 to limit the leftward movement of the piston module 320 (see Fig. 6).

A return spring 340 may be installed in a space formed between the second piston 345 and the retainer 380. The return spring 340 is supported and fixed to the retainer 380 by a snap ring 343.

The return spring 240 may be a coiled wave spring, a disc spring, or the like, as well as a multi coil spring as shown.

After the piston module 320 is inserted into the cylinder 330, the piston module 320 is fixed to the case 310 by the snap ring 341 to limit the axial movement.

6, 7, 8, and 9, the operating oil introduced into the cylinder 330 through the oil hole 312 and the oil pocket 314 presses the first piston 322 to the right in the drawing. The reaction force of the return spring 340 is overcome to press the working plates 360 and the friction disks 370.

Meanwhile, the working oil also acts on the second piston 345 through the oil passage 384 and the piston chamber 385 formed in the retainer 380 as shown in FIG. Pressurized by.

However, since the force acting on the first piston 322 is added to the action force of the second piston 345 through the fixing means 347, the piston module 320 has a greater force than the actuation plates ( 360 and the friction disks 370 are pressed. (Figure 9)

When the supply of the operating oil is stopped, the second piston 345 is restored to its original position by the action of the return spring 340, and is fixed by the fixing means 347 connected to the second piston 345. The first piston 322 is also restored to its original position.

The piston module 320 may be preassembled and delivered by a parts supplier before being supplied to a transmission assembly line. A preferred assembly example of the piston module 320 will be described below. (See Figure 7)

First, the sealing member 392 is installed in the retainer 380, and the first piston 322, in which the sealing members 323 and 324 are pre-installed, is assembled to the retainer 380.

Thereafter, the second piston 345 having the sealing member 385 installed therebetween is inserted between the retainer 380 and the extension 325 of the first piston 322, and then the first piston 322 and the second piston 322. The piston 345 is connected through the connecting means 347.

Thereafter, by returning the return spring 340 to the second piston 345 and compressing the return spring 340 by a press or the like, by engaging the snap ring 343 to the retainer 380, the piston Assembly of the module 320 is complete.

Typically, in a hydraulic brake, the return spring is assembled by compressing it more than the free height of the spring in order to give a constant pre-load to the piston, so that a press for pressing the return spring is installed in the transmission assembly line.

In the piston module 320 of FIG. 7, the return spring 340 needs to be compressed and assembled, which causes the second piston 345 to react against the left side in the drawing.

However, since the opposite side of the return spring 340 is in close contact with the retainer 380, the second piston 345 is left of the second piston 345 due to the preload of the return spring 340. Directional movement is limited. In addition, since the first piston 222 is connected to the second piston 345 by the fixing means 347, the leftward movement of the first piston 322 is also limited.

As described above, the piston module 320 according to the present invention is already applied with a preload of the return spring 340 therein during the assembly process, so that the piston module 320 is applied to the cylinder 330 without using a press in the transmission production line. Since only the snap ring 341 is inserted after insertion, the assembly process is simplified, and the assembly time is greatly reduced, thereby reducing the production cost of the transmission. (See Fig. 8)

In addition, the hydraulic brake according to the present invention uses a piston module that can increase the action force of the piston without expanding the existing hydraulic brake space, thereby increasing the torque capacity without increasing the number of friction disks, or increasing the number of friction disks. It can reduce and maintain the same torque capacity as the existing hydraulic brakes.

Accordingly, it is possible to reduce the drag torque generated when the hydraulic brake is not engaged, thereby improving the efficiency of the transmission and the fuel efficiency of the vehicle using the same.

According to embodiments of the present invention, as shown in FIG. 5, the number of friction disks may be reduced from 6 sheets (FIG. 1) to 4 sheets. Since the magnitude of the drag torque is directly proportional to the number of friction disks, it means that the drag torque can be reduced by 30% or more in the embodiment of the present invention.

In addition, according to the embodiment of the present invention, it is possible to increase the torque capacity of the brake by using the piston module, thereby reducing the magnitude of the hydraulic pressure acting on the brake. When the operating oil pressure of the brake is lowered, the discharge oil pressure of the oil pump can be lowered, thereby reducing the power consumption of the oil pump, thereby improving the efficiency of the automatic transmission.

So far, embodiments of the clutch module in which the piston, the retainer, and the return spring are pre-assembled have been described. However, the present invention is not limited thereto. Can be assembled directly to the transmission case.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and easily changed and equalized by those skilled in the art from the embodiments of the present invention. It includes all changes to the extent deemed acceptable.

1 is a cross-sectional view of a hydraulic brake of an automatic transmission according to the prior art.

2 is a cross-sectional view showing a non-operating state of the hydraulic brake of the automatic transmission according to the first embodiment of the present invention.

3 is a cross-sectional view of the piston module according to the first embodiment of the present invention.

4 is a cross-sectional view illustrating a process of assembling the hydraulic supply passage and the piston module of the piston module according to the first embodiment of the present invention.

5 is a cross-sectional view showing an operating state of a hydraulic brake in which the number of friction disks according to the first embodiment of the present invention is reduced.

6 is a cross-sectional view showing a non-operating state of the hydraulic brake of the automatic transmission according to the second embodiment of the present invention.

7 is a sectional view of a piston module according to a second embodiment of the present invention.

8 is a cross-sectional view showing a process of assembling the hydraulic supply passage and the piston module of the piston module according to the second embodiment of the present invention.

9 is a cross-sectional view showing an operating state of the hydraulic brake according to the second embodiment of the present invention.

Claims (19)

A cylinder formed in the case of the transmission; A piston module installed in the cylinder and operated by operating hydraulic pressure; Operating plates pressurized in the axial direction by operation of the piston module; And Friction disks that are alternately disposed and pressurized with the actuation plates; ≪ / RTI > The piston module is axially moved by the actuating hydraulic pressure and presses the actuating plates and the friction disks and is connected to each other to guide the first and second pistons and the axial movement of the first and second pistons. A retainer for forming the chamber between the first and second pistons so that the hydraulic pressure is applied to the first and second pistons, and an elastic force against the hydraulic pressure is applied to the first piston and / or the second piston. Includes an acting return spring, Hydraulic retainer, characterized in that the retainer is formed with a flow path for fluidly communicating the chambers. The method of claim 1, The case is an hydraulic brake, characterized in that the oil hole for supplying the operating hydraulic pressure to the piston module is formed. 3. The method of claim 2, Hydraulic brake, characterized in that the case is formed with one oil hole. The method of claim 1, One end of the retainer toward the case is in contact with the inner wall of the cylinder to limit the movement toward the case of the piston module hydraulic brake. The method of claim 4, wherein The retainer of the piston module is a hydraulic brake, characterized in that the axial movement is limited by the snap ring mounted to the case. The method of claim 1, Hydraulic brakes, characterized in that the parts constituting the piston module is pre-assembled and assembled to the case as one module. The method of claim 1, Hydraulic brakes, characterized in that the parts constituting the piston module is configured separately and assembled in each case. The method according to claim 6 or 7, Hydraulic brakes, characterized in that the first and second pistons are fixed to each other by a fixing means. The method of claim 8, The retainer is A first retainer in close contact with the inner diameter surface of the first piston and extending in a radial direction and in close contact with the outer diameter surface of the second piston; And A second retainer in close contact with the inner diameter surface of the first retainer to support the first retainer in an axial direction, and in close contact with the inner diameter surface of the second piston; Hydraulic brake comprising a. The method of claim 9, And the first retainer and the second retainer are integrally formed. The method of claim 9, Hydraulic brake, characterized in that the first retainer and the second retainer are formed separately and assembled. The method of claim 9, Hydraulic brake, characterized in that the return spring is disposed between the first retainer and the first piston. The method of claim 8, The inner circumferential surface of the retainer is in close contact with the first and second pistons, respectively, and a central portion of the inner circumferential surface of the retainer is in close contact with an extension of the first piston extending in the axial direction toward the second piston. Hydraulic brake. The method of claim 13, And said return spring is supported between said second piston and a retaining ring mounted to said retainer or case. The method of claim 5, Hydraulic brake, characterized in that the sealing member is provided between the case and the retainer. The method of claim 9, And a sealing member is provided between the outer diameter surface of the first piston and the case, and between the inner diameter surface of the first piston and the first retainer, respectively. The method of claim 9, And a sealing member is provided between the outer diameter surface of the second piston and the first retainer, and the inner diameter surface of the second piston and the second retainer, respectively. The method of claim 13, And a sealing member is provided between the inner diameter surface of the first piston and the case, and between the outer diameter surface of the first piston and the inner circumferential surface of the retainer, respectively. The method of claim 13, And a sealing member between the central portion of the retainer and the extension portion of the first piston, and between the outer diameter surface of the second piston and the inner circumferential surface of the retainer, respectively.

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