JPH064451U - Balance chamber structure of hydraulic piston for continuously variable transmission - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide a balance chamber structure for a hydraulic piston for a continuously variable transmission, which can improve responsiveness at the time of switching a gear ratio. A primary pulley 7 comprising a first fixed sheave 701 and a first movable sheave 701 fixed to an input shaft,
First hydraulic piston 1 for sliding the first movable sheave 701
3, a secondary pulley 10 including a second fixed sheave 112 and a second movable sheave 111 fixed to the output shaft 9.
And the second hydraulic piston 14 including the hydraulic chamber 25 formed by the fixed wall 28 that is opposed to the second movable sheave 111 and the second fixed sheave 112, and the fixed wall 28 and the movable wall 3.
Balance chamber 27 formed by 0 and both pulleys 7, 1
And an endless belt wound between 0. In particular, an oil communication portion 26 that communicates the hydraulic chamber 25 and the balance chamber 27 is provided on the outer peripheral side of the fixed wall 28. The oil communication portion 26 includes the balance chamber 27. Side small diameter portion 261 and the large diameter portion 26 on the hydraulic chamber 25 side
2 and a spherical body B interposed in the large diameter portion side 262.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention changes the winding diameter ratio of the belt wound between a pair of pulleys according to the expansion and contraction operation of the hydraulic piston attached to each pulley, and accordingly changes the gear ratio continuously. A pressure regulator for a hydraulic piston mounted on a continuously variable transmission, and in particular, a balance of a hydraulic piston for a continuously variable transmission that is formed by a hydraulic pressure relief hole so that the hydraulic chamber inside the hydraulic piston of the secondary pulley and the balance chamber can communicate with each other. Regarding the room structure.

[0002]

[Prior art]

 Conventionally, a belt drive type continuously variable transmission is known in which a drive belt is wound between a primary pulley and a secondary pulley, and the winding diameter ratio of the belts wound around both pulleys is changed to perform continuously variable transmission. Has been. This continuously variable transmission is equipped with both hydraulic pistons for operating the relative distance between the fixed sheave and the movable sheave of both the primary and secondary pulleys so that the line pressure will be in accordance with the vehicle operating information. The regulator valve regulates the pressure with an electromagnetic control valve, supplies the same line pressure to the hydraulic piston on the secondary pulley side, and uses the electromagnetic control valve for the same gear ratio control valve to achieve a target gear ratio according to the vehicle operating information. The gear ratio control hydraulic pressure obtained by adjusting the pressure is supplied to the hydraulic piston on the primary pulley side to change the gear ratio, and continuously variable transmission is performed.

As shown in FIG. 5, the hydraulic piston 101 of the secondary pulley 100 includes a hydraulic chamber 102 and a balance chamber 103 arranged outside the hydraulic chamber 102, and the hydraulic chamber 102 rotates integrally with a rotary shaft 104 of the secondary pulley 100. In addition, the movable sheave 105 and the rotating shaft 104 which are slidable relative to each other are formed by a fixed wall 106 which is integrated with the rotating shaft 104, and the balance chamber 103 is formed by the fixed wall 106 and the movable sheave 105 which is integrated with a movable wall 107. In this case, in particular, the hydraulic chamber 102 and the balance chamber 103 are communicated with each other by the hydraulic pressure drain hole 108, which holds the hydraulic pressure of the hydraulic chamber 102 at a predetermined pressure by the throttling action and supplies the hydraulic pressure to the balance chamber 103. Is used for.

During operation of the hydraulic piston, the hydraulic pressure from the hydraulic source is regulated to an appropriate line pressure by the hydraulic control means such as the regulator valve as described above. When this line pressure is supplied to and discharged from the hydraulic chamber 102 through the oil supply port 109, the movable sheave 105 slides on the rotary shaft 104, and the spacing between the movable sheave 105 and the fixed sheave is increased or decreased to change the belt ramp force of the belt. The secondary pulley 100 is switched to generate a target clamping force by. In this case, in particular, the oil in the hydraulic chamber 102 receives a centrifugal force, and the pressing force of the oil due to the centrifugal force (indicated by reference numeral fr1 in FIG. 5) is applied to the movable sheave 105, while the oil in the balance chamber 103 is reversed. Applies a pressing force of oil (indicated by reference numeral fr2 in FIG. 5) by the centrifugal force to the movable wall 107, and the pressing forces of the oil by both centrifugal forces cancel each other, whereby the movable sheave 105 presses the oil by the centrifugal force. It prevents the displacement from being caused by pressure.

In this case, the oil that has flowed into the hydraulic chamber 102 through the oil supply port 109 is gradually discharged from the hydraulic pressure drain hole 108 into the balance chamber 103. The hydraulic pressure drain hole 108 is configured so as to obtain a throttling effect such that the hydraulic pressure in the hydraulic chamber 102 is maintained at a value close to the line pressure even if the oil is discharged from here.

[0006]

[Problems to be solved by the device]

 However, the inner diameter of the hydraulic pressure drain hole 108 connecting the hydraulic pressure chamber 102 and the balance chamber 103 is constant, and therefore, if the rotation speed of the secondary pulley increases as the vehicle speed increases, the following problems occur. When the continuously variable transmission is driven, the rotation speed of the primary pulley reaches a maximum of about 5000 rpm, while the rotation speed of the secondary pulley reaches a maximum of about 10,000 rpm. Therefore, the influence of centrifugal force exerted by oil is extremely high. It is in a state where it is easy to receive That is, the inner diameter of the hydraulic pressure drain hole 108 is set so as to maintain the hydraulic pressure of the hydraulic chamber 102 at the time of low rotation at the line pressure, so that the gear ratio of the continuously variable transmission is lower than the high gear ratio (low gear). When the gear ratio is switched to a high gear, the oil in the hydraulic chamber 102 of the secondary pulley needs to be quickly discharged to the balance chamber 103. However, at this time, the oil pressure drain hole 108 has an inner diameter set so as to maintain the line pressure in a steady state at low rotation speed, and the oil cannot be rapidly removed. As a result, the oil in the oil pressure chamber 102 cannot be removed. It is switched to high rotation without being sufficiently eliminated. Therefore, the pressing force fr1 applied to the movable sheave 105 becomes excessively larger than the pressing force fr2 applied to the movable wall 107, and the movable sheave 105 is apt to be displaced due to the oil pressing force due to the centrifugal force, so that the proper clamping is performed. The force cannot be obtained, and the belt durability is reduced and the switching responsiveness is reduced.

An object of the present invention is to provide a balance chamber structure of a hydraulic piston for a continuously variable transmission, which can obtain an optimum clamping force and can improve the responsiveness at the time of switching a gear ratio.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention provides a first fixed sheave fixed to an input shaft, and a first movable sheave slidably disposed on the input shaft and opposed to the first fixed sheave. Primary pulley consisting of a sleeve, a first hydraulic piston for sliding the first movable sheave, a second fixed sheave fixed to the output shaft, and a second fixed sheave slidably on the output shaft. Fixed to the secondary movable sheave, the second movable sheave, and the output shaft and arranged opposite to the second fixed sheave sandwiching the second movable sheave. A second hydraulic piston, which is composed of a hydraulic chamber formed by a fixed wall, and slides the second movable sheave, and the hydraulic pressure across the fixed wall formed integrally with the fixed wall and the second movable sheave. The movable wall opposite the room In a continuously variable transmission including a balance chamber formed between the two pulleys and an endless belt wound between both pulleys, an oil communication portion that communicates the hydraulic chamber and the balance chamber is provided on the outer peripheral side of the fixed wall. The oil communication portion is characterized by comprising a small diameter portion on the balance chamber side, a large diameter portion on the hydraulic chamber side, and a sphere interposed in the large diameter portion side.

[0009]

[Action]

 The small diameter part of the oil communication part can be closed by a sphere that receives the hydraulic pressure of the hydraulic chamber, and this sphere is configured to open the small diameter part, so that the hydraulic chamber can be maintained at the line pressure and the small diameter part can be switched when switching. It can be opened to discharge the oil in the hydraulic chamber to the balance chamber.

[0010]

【Example】

 The balance chamber structure of the hydraulic piston for the continuously variable transmission shown in FIGS. 1 and 2 is attached to the continuously variable transmission 1 on the power transmission system P connected to the engine E of the vehicle. As shown in FIG. 2, a CVT ECU, which is an electronic control means (not shown), is connected to the continuously variable transmission (CVT) 1 in the power transmission system P, which drives the hydraulic control means of the continuously variable transmission 1. The shift control is performed by controlling the hydraulic pistons 13 and 14 which will be described later. Here, the continuously variable transmission 1 of FIG. 1 is connected to the crankshaft of the engine E via a fluid coupling 4 and a planetary gear type forward / reverse switching device 5.

Here, the continuously variable transmission 1 has a primary pulley 7 having a primary shaft 6 integrally connected to the output shaft of the forward / reverse switching device 5 and a secondary shaft 9 for outputting a rotational force to the speed reducer 8 side. A secondary pulley 10 is provided, and a steel belt 11 is stretched around the primary pulley 7 and the secondary pulley 10. The secondary shaft 9 is configured to transmit a rotational force to a drive wheel (not shown) via the speed reducer 8 and the differential 12. Both of the pulleys 7 and 10 are divided into two parts, and the movable sheaves 701 and 111 are fitted onto the fixed sheaves 702 and 112 so that they can rotate relative to each other and can be separated from each other. The movable sheaves 701 and 111 are provided with respective hydraulic pistons 13 and 14 that are operated to move relative to and away from the fixed sheaves 702 and 112.

It should be noted that the rotational speeds wp and ws of both the primary pulley 7 and the secondary pulley 10 are input to the CVTECU 2 by a rotation sensor (not shown), and the actual gear ratio in (= wp / ws) is calculated there. There is. Here, in the continuously variable transmission 1, the movable sheave 701 is moved closer to the fixed sheave 702 of the primary pulley 7 to increase the winding diameter of the primary pulley, and the movable sheave 111 is moved away from the fixed sheave 112 of the secondary pulley 10. The winding diameter is reduced to reduce the actual gear ratio in (primary rotation speed Wp / secondary rotation speed Ws), that is, the low gear ratio (high gear stage), and the reverse operation to operate the high gear ratio (low gear ratio). It is configured to achieve (dan).

Here, the hydraulic piston 13 includes a first hydraulic chamber 15 and a second hydraulic chamber 17 communicating with the hydraulic chamber via a communication path 16. Here, the first hydraulic chamber 15 is formed by the movable sheave 701 and the sheave side movable wall 19 fixed to the primary shaft 6. On the other hand, the second hydraulic chamber 17 is composed of a bowl-shaped wall 22 in which the flange 201 is fitted into the movable sheave 701 integrally with the primary shaft 6 and a sheave side fixed wall 21 fixed to the movable sheave 701 and slidingly contacting the inner peripheral wall of the flange 201. Has been formed.

The first hydraulic chamber 15 and the second hydraulic chamber 17 communicate with the primary inlet 24 on the casing 23 side through the central oil passage S of the primary shaft 6, and the same portion via the electromagnetic control valve 3. A control hydraulic pressure is supplied from a hydraulic pressure source side (not shown), whereby the movable sheave 701 and the sheave side fixed wall 21 integral with the movable sheave 701 can be slidably displaced by the hydraulic pressures of both chambers with good response. On the other hand, the hydraulic piston 14 includes a hydraulic chamber 25 and a balance chamber 27 that communicates with the hydraulic chamber via an oil drain hole 26 (see FIG. 3). Here, the hydraulic chamber 25 is formed of a movable sheave 111 and a fixed wall 28 that is integral with the secondary shaft 9, and a spring 29 that urges the two members in a detaching direction is mounted between both members. The balance chamber 27 is formed by a fixed wall 28 and a movable wall 30 that is integral with the movable sheave 111.

The hydraulic chamber 25 communicates with the secondary inlet port 32 on the casing 23 side via the central oil passage 31 of the secondary shaft 9, and the same portion is controlled via a solenoid control valve 33 from a hydraulic pressure source side (not shown) to control hydraulic pressure. (Line pressure) is supplied, and the necessary clamping force is generated in the secondary pulley 10. Here, as shown in FIG. 3, an oil drain hole 26 is formed in the portion a on the outer peripheral side of the fixed wall 28. The oil drain hole 26 is composed of a small diameter portion 261 on the balance chamber 27 side and a large diameter portion 262 of the hydraulic chamber 25. In particular, the large diameter portion 262 is provided with a steel ball B having an outer diameter larger than the inner diameter of the small diameter portion 261. Be fitted. A ring-shaped stop member 40 is welded to the opening of the large-diameter portion 262, and the stop member 40 has an inner diameter smaller than the outer diameter of the steel ball, and the steel ball loosely fitted in the large-diameter portion 262. Prevents B from leaving.

Here, in particular, the large-diameter portion 262 and the small-diameter portion 261 are formed such that their common center line L3 maintains a predetermined inclination angle α with respect to the fixed wall 28, that is, the rotation center line Ls of the secondary pulley. There is. Further, a connecting portion of the large diameter portion 262 with the small diameter portion 261 is formed on the cone surface 263, and the steel ball B rolls on the cone surface 262 to open / close the small diameter portion 261. The oil pump OP shown in FIG. 2, which is a hydraulic pressure source, is driven in conjunction with the engine to change the hydraulic pressure, but the hydraulic pressure is adjusted by a regulator valve (controlled by the electromagnetic control valve 33) (not shown). The pressure oil from the source is regulated to the line pressure and supplied to the secondary inlet 32, and the line pressure is regulated to the gear ratio control hydraulic pressure by the gear ratio control valve (controlled by the electromagnetic control valve 3). And is supplied to the primary inlet 24.

Such a balance chamber structure of the hydraulic piston for a continuously variable transmission is driven together with the drive of the continuously variable transmission 1 in the power transmission system P. Here, the pressure oil from the hydraulic pressure source on the engine side is controlled by the electromagnetic control valve 33 to be adjusted to the line pressure and supplied to the secondary inlet 32, and the line pressure is controlled by the electromagnetic control valve 3 to control the hydraulic pressure. And is supplied to the primary inlet 24. Here, when the vehicle is operating at a low speed, the secondary pulley 10 is in a low rotation speed, the steel ball B of the fixed wall 28 of the secondary pulley 10 receives the differential pressure Fp between the hydraulic chamber 25 and the balance chamber 27, and the secondary pulley 10 shown in FIG. As shown in a), the small diameter portion 261 is kept closed.

When there is the fixed wall 28 at the time of low rotation as shown in FIG. 4 (a), the differential pressure Fp and the centrifugal force F1 are applied to the steel ball B. The directions of the differential pressure Fp and the centrifugal force F1 are different, and at low speed, each component force Fps of the differential pressure Fp in the direction of the cone surface is larger than each component force F1s of the centrifugal force in the direction of the cone surface. The steel ball B blocks the small diameter portion 261. In this state, the oil supplied from the secondary inlet 32 to the hydraulic chamber 25 is not removed from the oil drain hole 26, and the line pressure can be secured, and the other primary pulley 7 also receives the proper control hydraulic pressure, and the predetermined winding is performed. The diameter can be secured, and by this, the actual speed ratio in (primary speed Wp / secondary speed Ws) can be switched to the target speed ratio.

On the other hand, when the vehicle is switched during high speed operation, a command to switch from a high gear ratio (low gear) to a low gear ratio (high gear) is issued from a CVT ECU (not shown), and particularly, the secondary pulley 10 Will be switched to high rotation. Therefore, it is necessary to remove a predetermined amount of oil in the hydraulic chamber 25 of the secondary pulley 10 into the balance chamber 27. At this time, first, the rotation speed of the secondary pulley 10 rapidly increases, and the steel ball B of the fixed wall 28 receives the differential pressure Fp1 between the hydraulic chamber 25 and the balance chamber 27, as shown in FIG. Steel ball B is subjected to a sudden increase in centrifugal force F2. For this reason, the component force F2s of the centrifugal force in the direction of the cone surface becomes large and exceeds each component force Fp1s of the differential pressure Fp in the direction of the cone surface. As a result, the steel ball B opens the small diameter portion 261 so that the oil in the hydraulic chamber 25 can be promptly removed to the balance chamber 27, and the oil pressing force fr1 due to the centrifugal force applied to the movable sheave 111 of the hydraulic chamber 25 and the oil balance balance. The pressing forces fr2 of the oil due to the centrifugal force applied to the movable wall 30 of the chamber 27 cancel each other out, the displacement of the movable sheave 111 due to the pressing force of the oil due to the centrifugal force is eliminated, and the switching to the appropriate gear ratio is smoothly responsive. Well done In the above description, one oil drain hole 26 was formed in the fixed wall 28, but instead of this, a plurality of oil drain holes 26 may be formed. In this case, in the case of high rotation switching. The oil drainage is further promoted, and the switching response can be further improved.

[0020]

[Effect of device]

 As described above, according to the present invention, when the primary pulley rotates at a low speed, the sphere that receives the hydraulic pressure in the hydraulic chamber closes the hydraulic pressure relief hole, and at the time of high rotation, the sphere that receives a centrifugal force of a predetermined value or more opens the small diameter portion. As a result, the hydraulic chamber can be easily maintained at the line pressure when the secondary pulley rotates at a low speed, and when switching to a high speed, the small diameter part can be quickly opened to drain the oil in the hydraulic chamber to the balance chamber, and the belt clamp Since the force can be optimized, the durability of the belt is improved, and the responsiveness of switching from a high gear ratio (low gear) to a low gear ratio (high gear) can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a balance chamber structure of a hydraulic piston for a continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a continuously variable transmission and a power transmission system including the hydraulic piston balance chamber structure of FIG.

FIG. 3 is a cross-sectional view of a fixed wall provided with an oil drain hole in the balance chamber structure of the hydraulic piston of FIG.

4 (a) is an operation explanatory view of a steel ball of an oil drain hole in the balance chamber structure of FIG. 1 at a low rotation speed, and FIG. It is an operation explanatory view at the time of high rotation.

FIG. 5 is a cross-sectional view of a main part of a conventional device.

[Explanation of symbols]

 1 continuously variable transmission 6 primary shaft 7 primary pulley 9 secondary shaft 10 secondary pulley 11 steel belt 13 hydraulic piston 14 hydraulic piston 15 first hydraulic chamber 17 second hydraulic chamber 111 movable sheave 112 fixed sheave 25 hydraulic chamber 26 oil drain hole 27 Balance chamber 28 Fixed wall B Steel ball 261 Small diameter part 262 Large diameter part 263 Cone surface

Claims (1)

[Scope of utility model registration request] 1. A primary pulley comprising a first fixed sheave fixed to an input shaft, a first movable sheave slidably disposed on the input shaft so as to face the first fixed sheave, and a first pulley. 1st hydraulic piston which slides 1 movable sheave, 2nd fixed sheave fixed to the output shaft, 2nd provided so as to be slidable on the said output shaft facing the said 2nd fixed sheave
From a secondary pulley composed of a movable sheave, the second movable sheave, and a hydraulic chamber formed by a fixed wall fixed to the output shaft and sandwiching the second movable sheave and facing the second fixed sheave. And a second hydraulic piston that slides the second movable sheave, and a movable wall that is integrally formed with the fixed wall and the second movable sheave and that faces the hydraulic chamber across the fixed wall. A continuously variable transmission including: a balanced chamber and an endless belt wound between both pulleys; and an oil communicating portion that communicates the hydraulic chamber with the balance chamber on the outer peripheral side of the fixed wall. The oil communication portion is composed of a small diameter portion on the balance chamber side, a large diameter portion on the hydraulic chamber side, and a sphere interposed in the large diameter portion side. Balance chamber structure of the piston.