JPS6267359A - Control method for v belt driven continuously variable transmission - Google Patents

Abstract

PURPOSE:To balance the thrust of both pulleys so as to improve a belt life and decrease a noise, by duty controlling a solenoid valve by an input torque signal detected by a sensor and changing the oil pressure in a pressure chamber of the output pulley in accordance with torque. CONSTITUTION:A transmission gives thrust in accordance with input torque to a pulley 3 of an input shaft 2 by a torque cam device 4 while oil pressure Pc to a pressure oil chamber 8 in a driven side pulley 7. The oil pressure Pc is obtained such that the line pressure in an oil path 30 is controlled by a solenoid pressure Ps through a speed ratio control valve 10. A control circuit 50, inputting a signal from a torque sensor 20 of the input shaft 2 in addition to an input speed, car speed, etc. in the driving side pulley 3, gives duty ratio to a solenoid valve 40, controlling the solenoid pressure Ps. here the control circuit 50, in which a relation between the input torque and the duty ratio is previously stored, controls thrust of the pulley 7 by a duty ratio signal in accordance with the input torque.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of controlling a V-belt continuously variable transmission, particularly when the vehicle is running at the lowest speed ratio or the highest speed ratio.

Conventional technology and its problems Conventionally, hydraulic chambers are provided in both the driving pulley and the driven pulley, and line pressure is applied to one hydraulic chamber to apply the tension necessary for torque transmission to the V-belt, while the other For example, Japanese Patent Application Laid-Open No. 175664/1983 discloses a V-belt type continuously variable transmission that performs continuously variable speed by supplying and discharging line pressure to and from a hydraulic chamber using a gear ratio control valve.

By the way, in order to provide the V-belt with the optimum tension required for torque transmission, it is most preferable to apply tension according to the input torque in order to improve the heald life and transmission efficiency. However, if tension is applied to the V-belt using line pressure as described above, the line pressure itself must be adjusted in accordance with the input torque, and in reality, it is difficult to achieve the 11M pressure.

Therefore, the above problem can be solved by providing one pulley with a torque cam device that generates a thrust commensurate with the input torque and controlling the other pulley hydraulically. However, when driving at the lowest speed ratio (maximum gear ratio) or highest speed ratio (minimum gear ratio), the effective diameter of the hydraulically controlled pulley must be maintained at its maximum. Line pressure is directly introduced into the chamber, and excessive side pressure acts on the V-belt, resulting in shortened life of the V-belt and generation of noise. The reason for this is that one pulley receives a thrust corresponding to the input torque generated by the torque cam device, while the other pulley receives an excessive thrust (line pressure) unrelated to the input torque. This is because an imbalance of thrust occurs.

Purpose of the Invention The purpose of the present invention is to balance the thrust of the driving pulley and the driven pulley when maintaining the maximum effective diameter of the hydraulically controlled pulley, thereby increasing the life of the V-belt and reducing noise. An object of the present invention is to provide a method for controlling a V-held continuously variable transmission.

Structure of the Invention In order to achieve the above object, the present invention provides a V-belt type in which one of the driving pulley or the driven pulley is provided with a torque cam device that generates a thrust commensurate with the input torque, and the other is provided with a hydraulic chamber. A continuously variable transmission, a gear ratio control valve that controls hydraulic pressure to the hydraulic chamber, a solenoid valve that controls the gear ratio control valve, a torque sensor that electrically detects the input torque of the input shaft, and a vehicle running. and a control circuit that controls the duty of the solenoid valve according to conditions, and the control circuit changes the duty ratio given to the solenoid valve by the signal of the torque sensor when the effective diameter of the pulley provided with the hydraulic chamber is at its maximum. This is to generate hydraulic pressure commensurate with the input torque in the hydraulic chamber of the pulley.

In other words, by detecting the input torque with a torque sensor and inputting this signal to the control circuit to change the duty ratio given to the solenoid valve, the oil pressure in the hydraulic chamber can be easily changed according to the input torque. , it is possible to eliminate the unbalance of thrust between the driving pulley and the driven pulley.

Description of an Embodiment In FIG. 1, a V-belt type continuously variable transmission 1 has a driving pulley 3 provided on an input shaft 2, a driven pulley 7 provided on an output shaft 6, and a belt wound between both pulleys 3 and 7. ↑J) Girder V belt 9
It has The drive pulley 3 includes a fixed sheave 3a, a movable sheave 3b, a torque cam device 4 and a tone spring 5 provided behind the movable sheave 3b.

In the torque cam device 4, a roller 4a attached to the input shaft 2 presses against a cam surface 3c formed on the back surface of the movable sheave 3b, and applies a thrust corresponding to the input torque of the input shaft 2 to the movable sheave 3b. The structure of the torque cam device 4 is not limited to this, for example,
2060, Japanese Patent Laid-Open No. 59-175666, etc. may be used. On the other hand, the driven pulley 7 is composed of a fixed sheave 7a, a movable sheave 7b, and a hydraulic chamber 8 provided behind the movable sheave 7b.By controlling the hydraulic pressure to the hydraulic chamber 8, the movable sheave 7b is moved in the axial direction. When activated, the gear ratio can be changed steplessly.

10 is a gear ratio control valve that controls the hydraulic pressure (hereinafter referred to as control hydraulic pressure PC) to the hydraulic chamber 8; and a spool 11;
and a spring 12 that always urges the spool 11 to the left.
It has Line pressure is introduced to the port 13 from a hydraulic source (not shown) via an oil path 30, and the boat 13 is opened and closed by a land lla on the left side of the spool 11. Port 14 adjacent to the right side of the boat 13
is connected to the hydraulic chamber 8 via an oil passage 31, and communicates with the left end chamber 15 via a communication hole 11b formed inside the spool 11. Therefore, in the left end chamber 15, 't
Control hydraulic pressure PC via rt circuit 31 and communication hole 11b
acts as back pressure and urges the spool 11 to the right.
I'm here. Note that the communication hole 1 formed inside the spool 11
1b, the same function can be obtained by providing another oil passage 32 connecting the oil passage 31 and the left end chamber 15, as shown by the broken line in the figure.

Oil passage 33 branched from oil passage 30 to which the line pressure was introduced
is in contact with the right end chamber] 6, and this oil passage 33 is provided with an opening 34 that is opened and closed by a -9-dollar 41 of a solenoid valve 40. Therefore, the hydraulic pressure (under 111, referred to as solenoid pressure PS) that is controlled by the solenoid valve 40 acts on the right end chamber 16, urging the spool 11 to the left. Further, a drain port 17 is formed adjacent to the right side of the port 14 communicating with the hydraulic chamber 8, and this drain port 17 is opened and closed by the land IIC at the center of the spool 11.

The above control oil pressure P. The outer diameter A of the land lla on the left side of the spool 11 that receives the solenoid pressure P is set larger than the outer diameter iMB of the land 1d on the right side that receives the solenoid pressure P. Therefore, the sliding resistance of the spool 11 and the solenoid valve 4
Even if oil leaks from the opening 34, which is opened and closed by 0, the spool []] is always pushed to the right and is in the neutral position shown in the drawing, that is, the land 1a on the left closes the port 13, and the land IIC in the center closes the port 13. is maintained near the position where the drain boat 17 is opened, and the spool 11 is not displaced more than necessary when the solenoid valve 40 is turned ON or OFF.
Next, when the solenoid valve 40 is turned OFF or ON, the oil passages can be immediately switched to achieve excellent responsiveness.

The above control oil pressure PC, solenoid pressure ps and spring 12
The following relational expression holds true between the spring force F and the spring force F.

The control circuit 50 receives electrical signals including input torque signals detected by the torque sensor 20 attached to the input shaft 2, in addition to signals corresponding to driving conditions such as the input rotation speed N1 of the drive pulley 3, throttle opening, and vehicle speed. The solenoid valve 40 is duty-controlled based on these signals, and the gear ratio of the V-belt continuously variable transmission 1 is made variable.

Here, the duty control means that a pulse signal with a constant period including an N time and an OFF time is given to the solenoid valve 40, and the ratio of the ON time to the period (referred to as duty ratio) is changed, so that the duty ratio is approximately equal to that of the solenoid valve 40. Control that generates proportional solenoid pressure. therefore,
Once the duty ratio is determined, the solenoid pressure is determined, and the control oil pressure is determined from the solenoid pressure using the above equation (1). In other words, once the duty ratio is determined, the oil pressure acting on the hydraulic chamber 8 is uniquely determined, and the thrust force of the driven pulley 7 is also uniquely determined.

Next, the operation of the V-belt type continuously variable transmission having the above configuration will be explained.

First, when accelerating with a constant throttle opening,
As shown by the solid line in Figure 2, it accelerates along straight line a while maintaining the lowest speed ratio, and when the input rotation speed N1 reaches a preset target input port of several N, it shifts to the shift region. . In this shift region, the gear is shifted toward a high speed ratio while maintaining the target input rotational speed N, and after reaching the maximum speed ratio, the vehicle is accelerated along the maximum speed ratio straight line.

In the above shift region, the actual input rotation speed N1 constantly fluctuates up and down, and the solenoid valve 40 changes depending on whether the input rotation speed N is larger than the target input rotation speed N.
Turning ○N or OFF will cause the vehicle to hunt. Therefore, as shown by the dashed line in FIG.
Upper and lower limit values with E are set, and when the actual input rotation speed N1 is outside the range of the upper and lower limit values, the solenoid valve 40
is turned ON or OFF continuously, and when it is within the range, the duty ratio is changed according to the difference between the input rotation speed N1 and the target input rotation speed Nl:. That is, when N, > N, +ΔN, D=O% (OFF) N, +Δ
When N, ≧N, ≧N, -ΔN, 2×ΔN.

When N, <N, -ΔN, D = 1.00% (ON) As a result, when the input rotation speed N, deviates significantly from the target input rotation speed N, the input rotation speed N1 is set to the target input rotation @! 1
．． The input rotation speed N is controlled so as to rapidly approach the target input rotation speed N, and when the input rotation speed N is close to the target input rotation speed N, the control is performed slowly.Therefore, hunting of i+i4 due to gear shifting can be prevented.

By the way, when traveling along the straight line a of the minimum speed ratio, it is necessary to increase the oil pressure in the hydraulic chamber 8 of the -1 driven pulley 7 to maintain the effective diameter at the maximum. At this time, if the duty ratio of the signal output from the control circuit 50 to the solenoid valve 40 is set to 100% and the line pressure is directly guided to the hydraulic chamber 8, the effective diameter can be maintained at the maximum. However, this poses a problem in that the thrust of the driven pulley 7 becomes excessive, and excessive lateral pressure acts on the V-belt 9, causing wear and tear on the V-heald 9 and belt noise.

The present invention focuses on the fact that the torque cam device 4 applies a thrust to the driving pulley 3 in accordance with the input l-ruk, and applies a thrust corresponding to the input l-ruk to the driven pulley 7, This balances the thrust of pulley 3.7. In order to generate a thrust corresponding to the input torque on the driven pulley 7, the relationship between the input torque and the duty ratio is stored in advance in the control circuit 50 as shown in FIG. From the figure, the duty ratio corresponding to the input torque detected by the torque sensor 20 is read out and a duty ratio signal of output 1: is output to the cylinder hull 40. As a result, solenoid and noid pressures proportional to the duty ratio G are generated, and these solenoid and noid pressures are calculated using equation (1) above, and the control oil [
The upper part is 4L, and this control oil pressure makes it possible to adjust the thrust of the driven pulley 7 according to the input torque.

Note that by setting the thrust of the driven pulley 7 to be slightly thicker than the thrust generated by the torque cam device 4 of the drive pulley 3, the lowest speed ratio can be stably maintained.

Although FIG. 3 shows a case in which the duty ratio increases linearly as the input torque increases, the relationship between the input torque and the duty ratio may be arbitrarily determined depending on the characteristics of the torque cam device 4. Can be set to .

In addition, the V-held continuously variable transmission 1 of the embodiment 1 and 2 is provided with a torque cam device 4 on the drive side pulley 3, and a driven side pulley 3.
1.17 Q: This is equipped with 1 pressure chamber 8,
On the contrary, a torque cam device may be provided in the driving pulley, the three hydraulic chambers, and the driven pulley 7. However, in this case, since the oil pressure in the oil pressure chamber is maximum at the highest speed ratio, this maximum oil pressure may be controlled according to the input torque.

Effects of the Invention As is clear from the above explanation, according to the present invention, when maintaining the maximum effective diameter of the hydraulically controlled pulley, the hydraulic pressure in the hydraulic chamber of this pulley is changed in accordance with the input torque. 1 of the driving pulley and driven pulley.
1 force can be balanced, the life of V<rut can be improved and noise can be reduced. Furthermore, since the oil pressure acting on the oil pressure chamber can be kept as low as necessary, the discharge loss of the oil pump can be reduced and fuel efficiency can be improved.

In addition, the input torque is determined by the electric signal from the torque sensor, and the oil pressure in the hydraulic chamber is determined by the duty ratio of the signal given to the solenoid valve, so both the input signal and the output signal of the control circuit are electric signals. It is possible to perform positive hydraulic control (corresponding to KC) based on the input torque.Therefore, there is no need for complex masterpieces such as changing line pressure according to the input torque, simplifying hydraulic control and reducing costs. It can be achieved.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of an example of a V-held continuously variable transmission according to the present invention, FIG. 2 is a shift diagram, and FIG. 3 is a diagram showing the relationship between input torque and duty ratio. l...V-held continuously variable transmission, 2...input shaft, 3...
... Drive side pulley, 4... Torque cam device, 7...
Driven example pulley, 8...Hydraulic chamber, 9...■ Belt, 1
0... Gear ratio control valve, 20... Druxe's, 40... Solenoid valve, 50... Control circuit. Applicant Daihatsu Motor Co., Ltd. Representative (patent attorney, external Hidetaka)

Claims (1)

[Claims] (1) A V-belt continuously variable transmission in which one of the driving pulley or the driven pulley is provided with a torque cam device that generates a thrust commensurate with the input torque, and the other is provided with a hydraulic chamber, and the hydraulic pressure to the hydraulic chamber is provided. a gear ratio control valve that controls the gear ratio, a solenoid valve that controls the gear ratio control valve, a torque sensor that electrically detects the input torque of the input shaft, and a control that controls the duty of the solenoid valve according to the vehicle running conditions. The control circuit changes the duty ratio given to the solenoid valve by the signal of the torque sensor when the effective diameter of the pulley provided with the hydraulic chamber is at its maximum, and the control circuit changes the duty ratio given to the solenoid valve according to the signal of the torque sensor, and applies the duty ratio to the hydraulic chamber of the pulley corresponding to the input torque. A control method for a V-belt continuously variable transmission characterized by generating hydraulic pressure.