JPS61218860A - Stepless speed changer with v-belt - Google Patents

Abstract

PURPOSE:To apply a proper belt pinching axial force to the two pulleys at all times by supplying or exhausting oil pressure to/from the oil pressure chambers in the pulleys in accordance with the speed changing condition and positive/negative torque transmitting condition. CONSTITUTION:To control the torque ratio, the oil pressure is supplied or exhausted to/from No. oil chambers 13, 21 in pulleys 2, 3 by the use of a valve 30 so as to change the effective belt dia. of each pulley. In response to the torque ratio control, an oil pressure in accordance with the axial force ratio is held in No.2 oil chamber 13 in the pulley 2 during positive torque transmission, and an oil pressure in accordance with the axial force ratio is held in No.2 oil chamber 21 in the pulley 3 during negative torque transmission. Therefore proper belt pincing axial force is applied to the two pulley at all times.

Description

Detailed Description of the Invention (a) Industrial Application The present invention relates to a continuously variable transmission using a V-belt, particularly a metal belt, and more specifically to a V-belt type continuously variable transmission suitable for being mounted on an automobile. Regarding machines.

(b) Conventional technology Conventionally, this type of V-belt type continuously variable transmission applies hydraulic pressure to the hydraulic piston of the secondary pulley to ensure the transmission torque capacity of the belt, and to the hydraulic piston of the primary pulley to change the speed. Hydraulic color l rod◆ΔT7 Shintokuyama 1p
City E++ /7'l R+1. The torque ratio is controlled by +-Joza cal balance. Specifically, for example, the area ratio of the hydraulic piston of the secondary pulley to the hydraulic piston of the primary pulley is set to 1:2, line pressure is always applied to the hydraulic piston on the secondary pulley side, and control is applied to the hydraulic piston on the primary pulley side. The valve is configured to supply or exhaust line pressure.

By the way, in a belt-type continuously variable transmission, a predetermined belt clamping pressure is required in order to transmit power without causing slip in the belt in response to input torque, but this belt clamping pressure is approximately equal to that of both pulleys. The same degree of axial force is required, and the required axial force F per unit input torque increases as the torque ratio goes from overdrive O/D to underdrive U/D, as shown in Figure 4. Draw a curve.

On the other hand, in order for the belt to maintain an arbitrary torque ratio, that is, a predetermined effective diameter of the input pulley and effective diameter of the output pulley, the belt pinching axial forces of both pulleys must be in the predetermined ratio shown in FIG. That is, in the case of no load state, as shown by A,
The primary side axial force Fp and the secondary side axial force Fs are distributed around the torque ratio 1 to overdrive 410F 0 and underdrive U/D, above and below F p / F s = 1, but when positive torque is transmitted, that is. When transmitting power from the primary pulley to the secondary pulley, as shown by B, a predetermined amount of large axial force is required on the primary side (Fp/Fs>1), and when transmitting negative torque such as during engine braking, the reverse As shown by C, a large axial force is required on the secondary side (F p/F s (1)).

By the way, most of the time when the vehicle is running, it is in the positive torque transmission state B, so the primary side axial force Fp is equal to the secondary side axial force F.
It is necessary to maintain the torque ratio in a state where it is large with respect to s. Therefore, in the positive torque transmission state, the secondary side axial force Fs is set to generate a belt clamping pressure to the extent that the belt does not slip. , the secondary side axial force F
It is sufficient if the primary side axial force Fp is applied in a manner corresponding to s, but in a negative torque transmission state C such as during engine braking or downshifting, the tendency is opposite to the above, that is, a large axial force is applied to the secondary side Fs. is required, and the secondary side axial force set based on the positive torque transmission state B causes slip in the belt.

For this reason, conventionally, in continuously variable transmissions, the oil pressure has been set in advance so that the secondary side axial force Fs is high, taking into consideration the negative torque transmission time C.

(c) Problems to be Solved by the Invention For this reason, the conventional continuously variable transmission has the following problems in the normal positive torque transmission state:
Belt clamping pressure that is higher than necessary is always acting on both pulleys, leading to a decrease in transmission efficiency, especially in low torque transmission conditions, worsening fuel efficiency, and reducing the durability of the belt. This has caused serious problems as a transmission for cars.

In addition, hydraulic control to the piston on the primary pulley side is
Since this is done by supplying or discharging with a control valve, the movable sheave is moved when discharging, that is, during a downshift operation.During a downshift operation, when a large amount of residue is discharged from the piston, it is necessary to ensure an appropriate residual pressure. However, if the residual pressure is set high, the shift time becomes longer.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems by always applying an appropriate belt pinching axial force to both pulleys.

(b) Means for solving the problem The present invention has been made in view of the above circumstances, and is
As shown in the figure, each movable sheave 2b, 3b of the primary pulley 2 and secondary pulley 3 is
Oil chambers 10, 17 and second oil chambers 13, 21 are installed, and the hydraulic pressure acting on these first and second oil chambers is configured to act independently on each movable sheave 2b, 3b as an axial force. . And the first oil chamber 1O21 of both pulleys 2 and 3
7, a hydraulic pressure corresponding to the input torque and torque ratio is constantly applied to the second hydraulic chamber 13.21 of both pulleys 2, 3,
The hydraulic pressure is configured to be supplied or discharged depending on the speed change state and the positive/negative torque transmission state.

ii. Based on the above-described configuration, hydraulic pressure corresponding to the belt torque capacity as shown in FIG. 4 acts on each of the first oil chambers 10 and 17 of the primary pulley 2 and secondary pulley 3. In order to control the torque ratio, a ratio control valve 30 is used to control the primary and secondary pulleys 2 and 3.
This is done by supplying or discharging hydraulic pressure to each of the second oil chambers 13 and 21, and changing the belt effective diameter of both pulleys. Furthermore, in accordance with the torque ratio control or by individual control, during positive torque transmission at a constant torque ratio, oil pressure is applied to the second oil chamber 13 of the primary pulley 2 in accordance with the axial force ratio shown in FIG. During negative torque transmission, a hydraulic pressure corresponding to the axial force ratio is held in the second oil chamber 21 of the secondary pulley 3.

(F) Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(2) The belt type continuously variable transmission 1 has a primary pulley 2 and a secondary pulley 3, as shown in FIG.

Further, the primary pulley 2 includes a fixed sheave 2a that is integrally formed with the shaft 5 and a movable sheave 2b that is slidably supported on the shaft 5 via a ball spline 6. It consists of a fixed sheave 3a integrally formed with the shaft 7 and a movable sheave 3b slidably supported on the shaft 7 via a ball spline 6. Further, a metal V-belt 8 is wound between the primary pulley 2 and the secondary pulley 3.

A cylinder 7 is integrally formed on the back surface of the movable sheave 2b of the primary pulley 2.
Inside is a first oil chamber 10 in which a lid 9 fixed on the shaft s is fitted in an oil-tight manner, and the back surface of the sheave 2b becomes a piston surface.
is formed.

Furthermore, the second cylinder 11 is attached to the shaft 5 so as to cover the cylinder 7.
A piston member 12 is fitted into the cylinder 11 in an oil-tight manner so as to come into contact with the end surface of the first cylinder 7, thereby forming a second oil chamber 13. In addition, 1 in the figure
4 is a cover for canceling the centrifugal oil pressure generated in the first oil chamber 10. On the other hand, a cylinder 15 is also integrally formed on the back surface of the movable sheave 3b of the secondary pulley 3, and a lid body 16 fixed on the shaft 7 is fitted in an oil-tight manner inside the cylinder 15. A first oil chamber 17 is formed in which the back surface of the sheave 3b serves as a piston surface. Further, a second cylinder 19 is fixed to the shaft 7 so as to cover the cylinder 15, and a piston member 20 is fitted into the cylinder 19 in an oil-tight manner so as to come into contact with the end surface of the first cylinder 15. Together, a second oil chamber 21 is formed. Note that 22 in the figure is a cover for canceling the centrifugal oil pressure generated in the first oil chamber 17.

The shaft 5 has an oil passage 25 from one end along the axis, and an oil passage 25 from the other end. l526 is formed, and similarly,
The shaft 7 is also formed with an oil passage 27 from one end and an oil passage 29 from the other end along the axis. And oil passages 25 and 27
is constantly supplied with oil pressure (line pressure) PL corresponding to the input torque and torque ratio as shown in FIG. There is. Moreover, the oil pressure from the ratio control valve 30 is applied to the other oil passages 26 and 29 through the pipes 31 and 32.
The oil is supplied or discharged through the oil holes 26a and 29b, and communicates with the primary side second oil chamber 13 and the secondary side second oil chamber 21, respectively. The ratio control valve 30 also has an inlet 30a communicating with the line pressure P, outports 30b and 30c communicating with the pipes 31 and 32, respectively, and drain ports 30d and 30d adjacent to each outport,
Further, springs 35 and 35 are compressed at both ends 30e and 30f of the spool, respectively, and the regulated control pressure Pc is applied to orifices 36 and 36, respectively.
It acts via the first or second solenoid valve 37a, 37b.

Since this embodiment has the above-described configuration, the line pressure PL is always supplied to each of the first oil chambers 10 and 17 on the primary side and the secondary side.
X: -h J, ta TNT & s, -99-
After 1 hour of EW action, both the primary and secondary pulleys constantly pinch the belt 8 with an axial force (see axial force F in FIG. 4) corresponding to an appropriate belt torque capacity.

In addition, the primary side second oil chamber 13 or the secondary side second oil chamber 13
Each oil chamber 21 has a ratio control valve 30.
(outbow) 30b and 30c, a pressure corresponding to the torque ratio is held.

That is, during positive torque transmission (see B in FIG. 3), no pressure is applied to the second oil chamber 21 of the secondary pulley 3, and no pressure is applied to the second oil chamber 13 of the primary pulley 2 (see B in FIG. 3). The pressure is held such that the axial force ratio Fp/Fs corresponds to the torque ratio. Therefore, in this state, an appropriate belt clamping pressure corresponding to the input torque and torque ratio is generated in the secondary pulley 3 by the hydraulic pressure in the first oil chamber 17, and in the primary pulley 2, the movable sheave 2
b In addition to the oil pressure in the first oil chamber 10 that acts directly on the back surface, an axial force corresponding to a predetermined axial force ratio F p / F s according to the torque ratio is applied to the oil pressure in the second oil chamber 13 to cause the piston member 12 The axial force on the primary side is balanced against the axial force on the secondary side.

On the other hand, when transmitting negative torque (see C in Figure 3),
Conversely, no pressure is applied to the second oil chamber 13 of the primary pulley 2, and no pressure is applied to the second oil chamber 21 of the secondary pulley 3.
Axial force ratio F p / F according to the torque ratio indicated by C in the figure
A pressure such that s is held is held. Therefore, in this state, in the primary pulley 2, the first oil chamber 10
Appropriate belt clamping pressure corresponding to the input torque and torque ratio is generated by the hydraulic pressure of Through this, an axial force matching a predetermined axial force ratio acts on the movable sheave 3b, and the axial force on the secondary side is balanced against the axial force on the primary side. Note that the oil pressure IIJ control for the second oil chamber 13.21 is performed by both solenoid valves 37a and 37b in the ratio control valve 30, either automatically according to the shift control described below or under independent control.

Further, in order to change gears from a constant speed running state with a predetermined torque ratio, for example to perform an upshift, the first solenoid valve 37a of the ratio control valve 30 is turned on.

Then, the discharge hole of the valve 37a opens, the spool of the control valve 30 moves to the left, and the pressure oil (line pressure) of the inboard 30a is discharged (30b).
It is supplied to the second oil chamber 13 of the primary pulley 3 via the pipe line 31 and the oil line 26, and the other outboard 30
c is connected to the drain port 30d, and the secondary pulley 3
The oil in the second oil chamber 21 is drained through the oil@29 and pipe line 32. As a result, the balance between the axial forces of the primary pulley 2 and the secondary pulley 3 is disrupted, and the effective diameter of the primary pulley 2 becomes larger (lower half figure), and the effective diameter of the secondary pulley 3 becomes smaller. (lower half diagram), both movable sheaves 2b and 3b are moved and the speed is changed to increase the speed ratio. At this time, the belt clamping pressure corresponding to the torque capacity of the belt is the first of both pulleys.
This is reliably guaranteed by the oil chambers 10 and 17. Also,
By pressing the solenoid valve 37a with duty #, the speed of shifting can also be controlled.

Conversely, to downshift, the second solenoid 37 b 1g of the ratio control valve 30 is turned on. Then, the discharge hole of the valve 37b opens, the spool moves to the right, and the import 30 is transferred to the outboard 30c.
The pressure oil of a is introduced, and the other outboard 30b communicates with the drain boat 30d. As a result, the oil in the second oil chamber 13 of the primary pulley 2 is drained, and pressure oil is supplied to the second oil chamber 21 of the secondary pulley 3, so that the primary pulley 2 has a small effective diameter (upward (half figure), and the secondary pulley 3 is moved so that its effective diameter becomes larger (upper half 8), and the speed is changed so that the speed ratio becomes lower. At this time, similarly, the first oil chambers 10, 1
The torque capacity of the belt is reliably guaranteed by the oil pressure of 7, and the shift speed can be controlled by controlling the duty of the solenoid valve 37b.

When the effective diameters of the primary pulley 2 and secondary pulley 3 are set so as to achieve a predetermined torque ratio, the first and second solenoid valves 37a and 37b are both turned on or off, and the spool is brought to the center position. It is returned and held at a position where both out ports 30b and 30c are closed.

At this time, the upshift is in an acceleration state, and normally, when the upshift becomes a constant speed driving state, it is often in a positive torque transmission state, but in this state, the second oil chamber of the primary pulley 2 13 is held in a state in which pressure oil acts on it and oil is removed from the second oil chamber 21 of the secondary pulley, and this state corresponds to the time of positive torque transmission described above.

Similarly, during a downshift, the vehicle is in a deceleration state, and when the downshift changes to a constant speed running state, it is often in a negative torque transmission state, but in this state, the secondary side second oil chamber 21 A state is held in which pressure oil acts on the primary side second oil chamber 13 and no pressure acts on the primary side second oil chamber 13, and this state corresponds to the time of negative torque transmission described above.

Therefore, normally, the axial force ratio F p / F is automatically adjusted according to the positive torque and negative torque transmission states by the gear change operation.
s is set and does not require frequent valve operations.

Next, another embodiment will be described based on FIG. 2.

The control valve 30' according to this embodiment has a hollow portion 4
A rack 40b is formed at one end of the spool 40, and an output gear 41 of a stepping motor is meshed with the rack 40b. Further, the spool 40 has an oil hole 40c communicating with an import 30'a to which line pressure PL is supplied, and an outboard hole 40c communicating with the second oil chamber 13 on the primary side.
Oil hole 40d and secondary side second oil chamber 2 that match b
Oil hole 40 that matches the out port 30'C communicating with 1
The hollow part 40a of the spool 40 has lands 42a and 42b for switching oil holes 40d and 40e.
A second spool 42 having a diameter is fitted therein. Further, the second spool 42 has a spring 43 compressed between it and the first spool 40 at one end, and a detection rod 45 integrally extended at the other end. is in contact with the movable sheave 2b of the primary pulley 2.

Since this embodiment has the above-described configuration, when the first spool 40 is moved in the direction indicated by the arrow U by the stepping motor (output gear) 41, the pressure oil in the import 30'a flows through the oil holes 40c, 40d and The oil is supplied to the second oil chamber 13 of the primary pulley 2 through the out port 30'b, and the oil hole 40e communicates with the right drain hole 40f consisting of the hollow portion 40a, so that the second oil chamber 21 of the secondary pulley 3 is supplied.
Oil is discharged from the casing 1, thereby causing the continuously variable transmission l to move in the upshift direction. Then, in communication with the movement of the movable sheave 2b of the primary pulley 2, the second spool moves in the direction of arrow U (right) via the detection rod 45, and its lands 42a and 42b block the oil holes 40d and 40e. As a result, the movable sheaves 2b and 3b of both pulleys are servo-controlled to positions based on the stepping motor. Similarly, when the first spool 40 is moved in the direction of the arrow, the continuously variable transmission 1 is servo-controlled in the downshift direction.

Note that speed change control is also possible by controlling the speed of the stepping motor.

(g) As explained above, according to the present invention, each movable sheave 2b, 3b of both the primary and secondary pulleys 2, 3
Since the first oil chambers 10 and 17 are provided to constantly apply oil pressure corresponding to the input torque and torque ratio, both pulleys 2 are always applied.
, 3 can ensure belt clamping pressure with appropriate torque capacity, and furthermore, movable sheaves 2b, 3b of both pulleys can be secured.
Hydraulic pressure is supplied or discharged to the second oil chambers 13, 21 that apply axial force to the axial force depending on the gear shifting state and the positive/negative torque transmission state. Therefore, the necessary axial force can always be applied to the primary pulley 2 or the secondary pulley 3, and in any transmission state, the appropriate axial force for that transmission state can be applied to both pulleys 2 and 3, and the belt can be maintained at all times. It is possible to perform reliable power transmission without slipping, and to improve transmission efficiency by eliminating excessive axial force. Due to this, power performance such as fuel efficiency and acceleration performance can be improved, and the durability of the belt 8 can be improved, and the belt type continuously variable transmission 1 can be brought closer to practical use as a transmission for an automobile. In addition, both the primary and secondary pulleys 2.3 each have a first oil chamber 10,
A predetermined pressure is applied by 17, and during gear shifting operation,
It is only necessary to apply a slight pressure to the second oil chamber 13 or 19 to change the balance of the pressure, which allows quick gear shifting operations and improves the ratio control valve 30.3.
0' structure can be simplified, and when changing gears,
Especially during kickdown, the first oil chamber 10 (17)
A predetermined pressure is applied to ensure residual pressure, allowing accurate gear shifting operations.

Also, the hydraulic pressure in the second oil chamber is controlled by the solenoid valves 37a and 3.
If the ratio control valve 30 is equipped with a servo machine WI42.45, fine control such as shift speed can be performed through duty control. The position can be set accurately and reliably, and furthermore, if regulated line pressure is supplied to the inboards 30a and 30'a of the valves 30 and 30',
The same line pressure can be applied to all oil chambers 10, 13, 17, and 19, and the valve structure can be simplified.

[Brief explanation of drawings]

FIG. 1 is an overall sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing another ratio control valve. FIG. 3 is a diagram showing the belt clamping axial force ratio with respect to the torque ratio, and FIG. 3 is a diagram showing the required axial force per unit input torque with respect to the torque ratio. 1...Continuously variable transmission, 2...Primary pulley,
2a...Fixed sheave, 2b...Movable sheave,
3... Secondary pulley, 3a... Fixed sheave, 3b... Movable sheave, 10, 17.
...First oil chamber, 13,21...Second oil chamber, 30
．． 30'...Ratio control valve) 37a,
37b...Solenoid valve, 42.45...
Servo mechanism.

Claims (4)

[Claims] (1) In a V-belt continuously variable transmission comprising a primary pulley and a secondary pulley each having a movable sheave and a belt wound around both pulleys, a first oil chamber and a A second oil chamber is installed, and the hydraulic pressure acting on the first and second oil chambers is configured to act independently on each movable sheave as an axial force. A V-belt type continuously variable transmission configured to constantly apply hydraulic pressure corresponding to a torque ratio, and to supply or discharge hydraulic pressure to the second oil chamber according to a gear change state and a positive/negative torque transmission state. (2) The V-belt type continuously variable transmission according to claim 1, wherein the V-belt is made of a metal belt, and the continuously variable transmission is a transmission mounted on an automobile. (3) The V-belt type continuously variable transmission according to claim 1, wherein the oil pressure in the second oil chamber is controlled by a ratio control valve having a solenoid valve. (4) The V-belt type continuously variable transmission according to claim 1, wherein the oil pressure in the second oil chamber is controlled by a ratio control valve having a servo mechanism.