JPS6331834A - Line pressure controller for v-belt type continuously variable transmission - Google Patents

Abstract

PURPOSE:To obtain a line pressure characteristic closer to an ideal line pressure characteristic in an area having a high speed change ratio, by providing a speed change ratio corresponding pressure regulation valve having a pressure regulating position variable with throttle pressure. CONSTITUTION:In a line pressure controller where a line pressure is fed to a driven pulley so as to control the hydraulic pressure of a drive pulley thus performing speed change, a line pressure regulation valve 10, a speed change corresponding pressure regulation valve 12 for regulating a speed change corresponding pressure and a throttle valve 14 for regulating the throttle pressure are provided. The speed change corresponding pressure regulation valve 12 is constructed with a movable valve body 42 being loaded by a spring 44, a spool 46 being inserted therein, a spring supporting member 50 being pressed by a speed change ratio detecting member 48 movable in accordance with the speed change ratio and two springs 52, 54 being arranged between said member 50 and the spool 46. Consequently, a speed change ratio corresponding pressure which increases as the throttle pressure increases can be obtained in an area having high speed change ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a line pressure control device for a V-belt continuously variable transmission.

(B) Prior Art A conventional line pressure control device for a V-belt type continuously variable transmission is disclosed in, for example, Japanese Patent Laid-Open No. 157554/1983. This line pressure control device for a V-belt continuously variable transmission is intended to obtain line pressure characteristics similar to that of an appropriate line pressure. Try to change the degree. For this purpose, the pilot pressure applied to the line pressure regulating valve is changed at a predetermined gear ratio.

In other words, in a region where the gear ratio is thicker than a predetermined value, the gear ratio pressure, which increases as the gear ratio becomes smaller, acts in the direction of lowering the pressure regulation value by the line pressure regulating valve, and in the gear ratio below a predetermined value, the gear ratio pressure increases. Instead, it is configured to apply line pressure. Thereby, curved line pressure characteristics can be obtained at a predetermined gear ratio.

(Problem that Han's invention attempts to solve) However, the line pressure control device for the conventional V-belt continuously variable transmission as described above does not have ideal line pressure characteristics over the entire range of gear ratio and engine load. In other words, as shown in Figure 1 of the above-mentioned publication, the ideal line pressure increases as the gear ratio increases, and the transmitted torque increases. However, the degree to which the transmitted torque is affected is different in the region where the gear ratio is small and the region where the gear ratio is large.In other words, in the region where the gear ratio is small, the maximum torque is transmitted and the minimum torque is transmitted. The difference in line pressure required to transmit torque is relatively small, but when the gear ratio is large, the difference between the line pressure required to transmit maximum torque and the required line pressure to transmit minimum torque is Although the ideal ideal line pressure has such characteristics, the line pressure control device for the V-belt continuously variable transmission disclosed in the above publication does not allow the throttle pressure to match the line pressure. On the other hand, the degree of overshadowing is constant over the entire gear ratio range. Therefore, if the line pressure characteristics are set so that the necessary line pressure is obtained on the large gear ratio side, the throttle If the opening degree is small, the line pressure will be higher than necessary.If the line pressure is higher than necessary, it will have a negative impact on the durability of the belt, and it will also cause problems with the oil pump. Loss increases and efficiency decreases.Also, since the pressure regulating valve that regulates the pressure corresponding to the gear ratio has to regulate high oil pressure in the area where the gear ratio is small, the reaction force will be large. There is also the problem that the friction contact portion of the mechanism that detects the gear ratio becomes scratchy.

The present invention aims to solve these problems.

(d) Means for Solving the Problems The present invention applies two spring forces to the pressure regulating valve corresponding to the gear ratio to create bending characteristics of the line pressure, and also adjusts the pressure regulating position of the pressure regulating valve corresponding to the gear ratio. The above problem is solved by changing the throttle pressure according to the throttle pressure. That is, the line pressure control device for a V-belt continuously variable transmission according to the present invention includes a line pressure regulating valve (10) that regulates the pressure of oil discharged from an oil pump to create line pressure, and a line pressure regulating valve (10) that regulates the throttle pressure according to the engine load. a throttle valve (14) that adjusts the speed ratio and a speed ratio corresponding pressure regulating valve (12) that adjusts the speed ratio corresponding pressure that changes depending on the speed ratio and the throttle pressure;
The line pressure regulating valve is configured to regulate pressure using the throttle pressure and gear ratio corresponding pressure as pilot pressure, and the gear ratio corresponding pressure regulating valve has a first spring ( 52) and a second spring (54) that applies a pushing force in a region where the gear ratio is larger than a predetermined value. It is said that the third
The valve body is configured so that the position of the valve body in the wheel direction changes depending on the balance between the spring (44) and the throttle pressure.

Note that the parts in parentheses indicate corresponding members in the embodiments described later.

(e) Line pressure in action Due to the pressure regulating action of the pressure regulating valve, the line pressure changes in accordance with the throttle pressure and the pressure corresponding to the gear ratio. The valve body of the speed ratio corresponding pressure regulating valve moves in accordance with the throttle pressure, and the pressure regulating position changes. Therefore, in a region where the speed ratio is large, the larger the throttle pressure is, the larger the speed ratio corresponding pressure becomes. Therefore, the degree of influence of the throttle pressure on the line pressure becomes greater in the range of shift sinking, and characteristics closer to the ideal can be achieved.

(F) Embodiment FIG. 1 shows an embodiment of the present invention. The line pressure control device for this V-belt type continuously variable transmission is known, for example, from Japanese Patent Application Laid-Open No. 61-105
This is applied to a V-belt type continuously variable transmission, as shown in Japanese Patent No. 353, in which line pressure is constantly supplied to the driven pulley and gear changes are performed by controlling the oil pressure of the drive pulley. Line pressure regulating valve 1o to regulate pressure
, a gear ratio corresponding pressure regulating valve 12 that regulates the gear ratio corresponding pressure, and a throttle valve 14 that regulates the throttle pressure. The line pressure regulating valve 10, which is a pressure regulating valve that regulates the oil pressure of an oil passage 18, which is a discharge pressure oil passage of the oil pump 16, that is, the line pressure, has a spool 20 and a spring 22.

The oil pressure in the oil passage 18 acts on the port 24 and pushes the spool 20 to the right in FIG. 1 against the force of the spring 22.
Pressure regulation is performed by discharging the hydraulic pressure in the oil passage 18 to the drain port 26.

A throttle valve 14 is connected to the port 28 of the line pressure regulating valve 10.
Throttle pressure is applied to the port 32 through the oil passage 30, and pressure corresponding to the gear ratio is applied to the port 32 from the oil passage 34. Acts as a pilot pressure to push the That is, the line pressure in the oil passage 18, which is regulated by the line pressure regulating valve 10, changes depending on the throttle pressure in the oil passage 30 and the pressure corresponding to the gear ratio in the oil passage 34.

The throttle valve 14 has a spool 36, and is configured such that a pressing force from a vacuum diaphragm 38 acts on the spool 36.

The vacuum diaphragm 38 generates a pressing force that is inversely proportional to the engine intake pipe negative pressure. The throttle valve 14 uses the line pressure from the oil passage 18 as an oil pressure source to perform a pressure regulating action so that the pressing force from the vacuum diaphragm 38 and the oil pressure at the port 40 are balanced, and outputs this to the oil passage 30. The throttle pressure output to the oil passage 30 has characteristics as shown in FIG. 2 with respect to the engine intake pipe negative pressure.

The speed ratio compatible pressure regulating valve 12 includes a movable valve body 42,
A spring 44 (third spring) that pushes the movable valve body 42 to the left in FIG.
a spool 46 fitted into a valve hole in the spring support member 50;
and the two springs 5 disposed between the spool 46 and the spool 46.
2 (first spring) and spring 54 (second spring), and a hollow sleeve 56 fixed to movably support the spring support member 50. The movable valve body 42 is movable in the axial direction,
Although FIG. 21 shows the state in which it has moved to the leftmost side, it is possible to move it by one dimension to the right. Movable valve body 4
2 is always pressed to the left in FIG. 1 by a spring 44, and the hydraulic pressure of the port 58 acts in the opposite direction. The board 58 has an oil passage 30
throttle pressure is always applied. A spool 46 provided in the valve hole of the movable valve body 42 is connected to the oil passage 1.
Using the line pressure supplied from 8 as a hydraulic source, pressure regulation is performed so that the hydraulic pressure at port 60 is balanced with the forces acting from springs 52 and 54, and this is output to oil path 34.

For example, the gear ratio detection member 4B is connected to a member that constantly engages with a circumferential groove provided on the outer periphery of the driven pulley and moves in the axial direction together with the groove, and when the gear ratio is small, it is located to the right in FIG. It is configured to move to the left as the gear ratio increases. Therefore, the springs 52 and 54 are compressed as the gear ratio increases. However, the inner spring 54 is pressed by the spring support member 50 only when the spring support member 50 moves to the left to a predetermined position. That is, below a predetermined speed ratio, only the force of the spring 52 acts on the spool 46, and above a predetermined speed ratio, the forces of both springs 52 and 54 act on the spool 46.

Next, the operation of this embodiment will be explained.

As described above, the throttle valve 14 applies throttle pressure corresponding to the pressing force from the vacuum diaphragm 38 to the oil passage 30.
Output to. As shown in FIG. 2, the throttle pressure in the oil passage 30 has a characteristic that it decreases as the engine intake pipe negative pressure increases. The pressure regulating valve 12 corresponding to the gear ratio is a spring 52
The oil pressure of the oil passage 34, that is, the pressure corresponding to the gear ratio, is regulated to correspond to the forces acting from and 54. spring 52
The forces 54 and 54 change depending on the position of the gear ratio detection member 48. When the speed change/ratio detection member 48 is moving to the small speed ratio side, that is, to the right in FIG.
4 is in an uncompressed state, and only the force of the spring 52 acts on the spool 46, so that the pressure corresponding to the gear ratio in the oil passage 34 changes relatively quickly in accordance with the movement of the gear ratio detection member 48. When the gear ratio detection member 48 moves to a predetermined position and the spring 54 is also compressed, the degree of change in the force of the springs 52 and 54 increases with respect to the amount of movement of the gear ratio detection member 48, and the pressure corresponding to the gear ratio increases. The degree of change increases. In other words, the gear ratio corresponding pressure has a curved characteristic at a predetermined gear ratio. However, since the position of the movable valve body 42 changes depending on the position of the throttle pressure acting from the oil passage 30, the speed ratio corresponding pressure is also influenced by the throttle pressure. For example, when the negative pressure is 300 mmHg and the throttle pressure is the minimum value, the force pushing the movable valve body 42 to the right in FIG. The spool 46 that performs this movement moves to the left in FIG. 1 (the state shown in FIG. 1).
, the amount of compression of springs 52 and 54 decreases. That is, the gear ratio corresponding pressure becomes lower. On the other hand, the negative pressure is Om
When mHH is reached, the force pushing the movable valve body 42 to the right in FIG. 1 increases, and the movable valve body 42 compresses the spring 44 and moves to the right. Therefore, the amount of compression of springs 52 and 54 increases. That is, the gear ratio corresponding pressure becomes higher. The amount of movement of the movable valve body 42 with respect to negative pressure has a relationship as shown in FIG. in the end,
The pressure corresponding to the gear ratio in the oil passage 34 changes depending on both the gear ratio and the negative pressure, and has characteristics as shown in FIG. 4.

That is, when the negative pressure is OmmHz, the gear ratio corresponding pressure bends at a gear ratio of 0.8, and when the negative pressure is 300 m
In the case of mHg, the pressure corresponding to the gear ratio bends at, for example, 1.2. Furthermore, the influence of negative pressure is greater on the larger gear ratio side. The gear ratio corresponding pressure shown in FIG. 4 and the throttle pressure shown in FIG.
It acts on the boats 32 and 28 of the line pressure regulating valve 10 via. The line pressure regulating valve 10 is connected to the boats 32 and 28.
Since the line pressure of the oil passage 18 is regulated using the hydraulic pressure acting on the hydraulic pressure as the pilot pressure, the line pressure changes according to the throttle pressure and the pressure corresponding to the gear ratio. That is, the line pressure increases according to the throttle pressure and also increases according to the gear ratio.

Moreover, the gear ratio corresponding pressure increases as the negative pressure decreases, that is, as the throttle pressure increases, in the range of gear ratios greater than 0.8 to 1.2.

Therefore, the influence of the throttle pressure on the line pressure increases in a region where the gear ratio is equal to or higher than a predetermined value.

As a result, line pressure characteristics as shown by the solid line in FIG. 5 are obtained. In Figure 5, negative pressure Om on the large gear ratio side
The difference P1 between the line pressure of mHg and the line pressure of negative pressure 300 mmHg is larger than the difference P2 between the line pressure of negative pressure OmmHH and the line pressure of negative pressure 300 mmHg on the small gear ratio side. As a result, the characteristics are closer to the ideal line pressure as shown by the broken line. Line pressure with such characteristics always acts on the cylinder chamber of the driven pulley. As a result, an appropriate force is always applied to the V-belt, improving the durability of the V-belt and the boot.

Furthermore, the oil pump 16 does not need to discharge more discharge pressure than necessary, reducing loss and improving the efficiency of the continuously variable transmission as a whole. In addition, the spring 5 in the region where the gear ratio is small
2, the reaction force acting on the gear ratio detection member 48 is small, and wear of the meshing portion between the gear ratio detection member 48 and the driven pulley, which is an integral member, can be reduced.

(g) As described in detail, according to the present invention, the pressure regulating position of the pressure regulating valve corresponding to the gear ratio is changed according to the throttle pressure, so that the throttle pressure in the region of gear sinking is changed. By increasing the degree of influence, line pressure characteristics that more closely approximate ideal line pressure characteristics can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing throttle pressure characteristics, Fig. 3 is a diagram showing the amount of movement of the movable valve body, and Fig. 4 is a diagram showing pressure characteristics corresponding to gear ratio. , FIG. 5 is a diagram showing line pressure characteristics. 10... Line pressure regulating valve, 12... Pressure regulating valve corresponding to gear ratio, 14... Throttle valve, 16... Oil pump, 42... Movable valve body, 44... Third spring, 48... Gear ratio detection member, 52... First spring, 54... Second spring. Patent Applicant: Nissan Motor Co., Ltd. Agent: Patent Attorney Toshiyuki Miyauchi

Claims (1)

[Scope of Claims] A line pressure control device for a V-belt continuously variable transmission that has a driving pulley, a driven pulley, and a V-belt wrapped around both pulleys, and in which line pressure is always supplied to the driven pulley, A line pressure regulating valve that regulates the pressure of oil discharged from the oil pump to create line pressure, a throttle valve that regulates throttle pressure according to the engine load, and a pressure regulating gear ratio corresponding pressure that changes according to the gear ratio and throttle pressure. The line correct pressure regulating valve is configured to perform a pressure regulating operation using the throttle pressure and the gear ratio corresponding pressure as pilot pressure, and the gear ratio corresponding pressure regulating valve is configured to adjust the pressure according to the gear ratio. Correspondingly, the first spring that always applies a pushing force and the second spring that applies a pushing force in a region where the gear ratio is larger than a predetermined value perform a pressure regulating action, and the pressure regulating valve corresponding to the gear ratio. A line of V-belt continuously variable transmissions, characterized in that the valve body is movable in the axial direction, and the axial position of the valve body changes depending on the balance between the third spring and the throttle pressure. Pressure control device.