JPH028929B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a hydraulic control device for a V-belt continuously variable transmission for a vehicle. [Prior Art] A V-belt continuously variable transmission can be used as an automatic transmission for vehicles such as automobiles in combination with a planetary gear transmission for switching forward and reverse. Figure 30 shows
This figure shows a conventional continuously variable transmission proposed in Japanese Unexamined Patent Publication No. 157930/1983. An input shaft a is provided with a fixed pulley b and a movable pulley c, and an output shaft d is provided with a fixed pulley b and a movable pulley c.
is provided with a fixed pulley e and a movable pulley f, a belt g is stretched between an input shaft a and an output shaft d, and fluid from a pump j is supplied to oil passages h and i through valves k and l. The movable pulleys c and f are moved by supplying and discharging the fluid through the movable pulleys c and f.
On one end of the spool m of the valve l, fluid pressure proportional to the rotational speed of the input shaft a is applied by a pitot tube n, and on the other end of the spool m, a fluid pressure proportional to the rotation speed of the input shaft a is applied to the other end of the spool m. This pressure is applied via lever q and spring r. Furthermore, fluid pressure proportional to the rotational speed of the input shaft a is applied to one end of the spool s of the valve k by a pitot tube n, and the other end of the spool s is connected to the movable pulley c of the input shaft a. The pressure of the detection rod t, which is displaced by the pressure, acts via the lever u and the spring v. In the above configuration, the line pressure generated in the oil path i is caused by the fluid pressure generated by the pitot tube n depending on the rotation speed of the input shaft a and the spring v which changes due to the rotation of the lever u linked to the movement of the detection rod t. The oil pressure is controlled by the balance with the load, and increases as the torque ratio increases, and increases as the rotation speed of the input shaft decreases. [Problems to be Solved by the Invention] However, in the above-mentioned conventional continuously variable transmission, the line pressure is set relatively high when the torque ratio is large and the input shaft rotational speed is small when the engine is stopped or at low speed. This oil pressure is suitable when the engine output torque is large when the vehicle is started, but it becomes an unnecessarily high oil pressure when the vehicle is not started. Therefore, when the engine is stopped or at low speed and the throttle opening is small, the torque ratio is set high, and the line pressure is set relatively high in response to the hydraulic pressure responsive to the torque ratio. However, in such cases, the engine speed is close to idling and the oil pump discharges little, making it difficult to maintain line pressure.Furthermore, the oil temperature rises due to a decrease in the amount of oil supplied to the oil cooler. This has the problem of inviting The present invention solves the above problem, and provides a hydraulic control device for a V-belt continuously variable transmission for vehicles, which is capable of stabilizing line pressure during stoppage or slight movement, and preventing oil temperature from rising. The purpose is to provide [Means for Solving the Problems] For this purpose, the hydraulic control device for the V-belt type continuously variable transmission for vehicles of the present invention is provided with an input pulley having a variable effective diameter and an output pulley that is attached to an input shaft and an output shaft, respectively. In a V-belt type continuously variable transmission for a vehicle, which is composed of a side pulley and a drive band stretched between these pulleys, and controls the torque ratio between the input and output shafts by adjusting the effective diameter of the pulley using hydraulic pressure, A hydraulic source, a pressure regulating device that regulates the pressure of hydraulic oil from the hydraulic source to generate line pressure, a hydraulic servo that is supplied with the line pressure and generates a clamping force for the drive band according to the line pressure, and a throttle. The invention is characterized by comprising a pressure-reducing means for setting the line pressure low when the opening degree is below a predetermined value and the torque ratio is above a predetermined value. [Operation and Effects of the Invention] In the present invention, as shown in FIG. 2, for example, when in the D range, only the oil passage 3 of the manual valve 62 communicates with the oil passage 1, and the oil passage 4 and the oil passage 5 communicate with each other. is being depressurized. At this time, in the shift control mechanism 70, the shift control solenoid 7
4 is in the OFF state and line pressure is being supplied to the oil chamber 713, the spool 712 is positioned to the right, so that the oil passage 3 and the oil passage 13 are connected, and the line pressure is supplied to the oil passage 3. Hydraulic servo 49 of multi-disc clutch 45 for forward movement where line pressure passes through oil passage 13
The vehicle is now able to move forward. Then, when the torque ratio T is high such as t ₃ < T ≦ t ₄ , the pressure in the oil passage 9 is exhausted from the drain port 666 as shown in FIG. 5C, and the throttle pressure is expressed as D in FIG. 8. . However, since the port 663 is opened and the oil passage 1 and the oil passage 6 communicate with each other, the throttle opening θ is within the low range of 0≦θ≦θ ₁ %, and the spool 641 of the detent valve 64 is in the range shown in FIG. 4A. As shown in , while the oil passage 6 is on the left side in the figure, the oil passage 6 is closed by the spool 641 and pressure is discharged from the oil passage 7 from the manual valve 62 via the oil passage 5, but the throttle opening θ is θ ₁ In the high range of %<θ≦100%, the spool 641 moves as shown in FIG. 4B, and the oil passage 6 and the oil passage 7 communicate with each other, and detent pressure is generated in the oil passage 7. As a result, the line pressure has a characteristic that changes stepwise at θ=θ ₁ %, as shown in area 2 of FIG. 9 and area 1 of FIG. 10. In addition, in the P and N ranges, oil passages 3, 4 and 5 are all depressurized in the manual valve 62, and since the oil passage 5 is depressurized, the line pressure that is the output of the regulator valve 61 is the same as in the D range. It will be the same. In this line pressure adjustment, the manual valve 62
is shifted to the D, N, and P shift positions, the line pressure when the torque ratio T is in the high range of t ₃ < T ≦ t ₄ is determined by the throttle opening as shown in the characteristic curve in Figure 10. The reason for setting θ so low at ₁ % or less is that if the line pressure is set high in operating conditions such as idling where the throttle opening θ is small and the pump discharge amount is low, oil will leak from various parts of the hydraulic circuit due to high oil temperature. This is because when there is a large leak, it becomes difficult to maintain line pressure, and furthermore, the oil temperature increases further due to a decrease in the amount of oil supplied to the oil cooler, which is likely to cause trouble. Therefore, according to the present invention, the line pressure is set low when the throttle opening is small and the torque ratio is large, such as when the vehicle is stopped or moving slightly, so the line pressure can be stabilized even if the oil pump discharge amount is small. In addition, due to the low line pressure, the amount of oil leaking from various parts is reduced, and sufficient oil is supplied to the oil cooler, so unnecessary increases in oil temperature can be prevented. [Examples] Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an automobile transmission using a continuously variable transmission. 100 is the engine, 102 is the carburetor, 20
is a transmission device provided between the engine 100 and the drive side axle, which includes a hydraulic fluid coupling 21 connected to the output side 101 of the engine, and a reduction gear mechanism 23 connected to the differential gear 22. , a V-belt type continuously variable transmission 30, and a planetary gear transmission 40 for forward/reverse switching. Fluid coupling 21 is well known and consists of a pump impeller 211 and a turbine runner 212 connected to a torque converter output shaft 214. It should be noted that other fluid torque converters or mechanical clutches may be used in place of the fluid coupling. The V-belt type continuously variable transmission 30 is the continuously variable transmission 3.
Fluid coupling output shaft 2 which is the input shaft of 0
14, a movable flange 312 provided to face the fixed flange 311 to form a V-shaped space, and a hydraulic servo 313 that drives the movable flange 312. , a fixed flange 321 connected to the intermediate shaft 26 which is the output shaft of the continuously variable transmission 30, and a movable flange 32 provided to face the fixed flange 321 and form a V-shaped space.
2, an output pulley 32 consisting of a hydraulic servo 323 that drives the movable flange 322, and a V-belt 33, which is a drive band connecting the input pulley 31 and the output pulley 32.
This is a well-known system consisting of The above input pulley 31 and output pulley 32
The variable position L of the movable flanges 312 and 322 is 0 to l ₂ to _{l 3} to _{l 4} (0 < l ₂ < l ₃ < l ₄ ), which causes torque to be generated between the input shaft 214 and the output shaft 26. ratio T
Continuously variable speed is performed in which the speed changes within the range of _t1 to _t2 to _t3 to _t4 ( _t1 < _t2 < _t3 < _t4 ). In this embodiment, the pressure receiving area of the input side hydraulic servo 313 is approximately twice as large as the pressure receiving area of the output side hydraulic servo 323, and the hydraulic pressure applied to the hydraulic servo 313 is equal to or equal to the hydraulic pressure applied to the hydraulic servo 323. Even if the input side movable flange 312 is small, the movable flange 312 on the input side is formed to obtain a larger driving force than the movable flange 322 on the output side. This increase in the pressure receiving area of the hydraulic servo 313 is achieved by increasing the diameter of the hydraulic servo or by employing a piston having a double pressure receiving area in the hydraulic servo. The planetary gear transmission 40 for forward/reverse switching includes a sun gear 41 connected to the intermediate shaft 26, which is the output shaft of the continuously variable transmission 30, and a ring gear engaged with the transmission case 400 via a multi-disc brake 42. 4
3. A double planetary gear 44 rotatably meshed between the sun gear 41 and the ring gear 43, which rotatably supports the double planetary gear 44 and is connected to the intermediate shaft 26 via a multi-plate clutch 45; The system further includes a planetary carrier 46 connected to a second intermediate shaft 47 that is the output shaft of the planetary gear transmission 40, a hydraulic servo 48 that operates the multi-disc brake 42, and a hydraulic servo 49 that operates the multi-disc clutch 45. Ru. This forward/reverse switching planetary gear transmission 40 includes a multi-plate clutch 4.
5 is engaged and the multi-disc brake 42 is released, a forward gear with a reduction ratio of 1 is obtained, and the multi-disc brake 42 is released.
5 is released and the multi-plate brake 42 is engaged, it becomes a reverse gear with a reduction ratio of 1.02. This reduction ratio of 1.02 in reverse is smaller than the reduction ratio in reverse of a normal automobile transmission, but in this example, the reduction ratio obtained in a V-belt continuously variable transmission (for example,
2.4), the reduction gear mechanism 23 described later performs the reduction, so that an appropriate reduction ratio can be obtained as a whole. The reduction gear mechanism 23 is a V-belt continuously variable transmission 3
This is to compensate for the fact that the shift range obtained with 0 is lower than the shift range achieved by a normal vehicle transmission, and the torque is increased by shifting with a reduction ratio of 1.45 between the input and output shafts. The differential gear 22 is connected to an axle (not shown) and performs final deceleration of 3.727:1. FIG. 2 shows a hydraulic control circuit for controlling the continuously variable transmission in the transmission shown in FIG. The hydraulic control circuit includes a hydraulic power source 50 and a hydraulic adjustment device 6.
0. Multi-plate brake 4 in planetary gear transmission 40
2 and a shift control mechanism 70 that controls the timing of engagement of the multi-plate clutch 45 and alleviates the impact during N-D and N-R shifts, and a torque ratio control device 80. The hydraulic adjustment device 60 includes a manual valve 62 that is manually operated by a shift lever (not shown), a detent valve 64 and a throttle valve 65 that output detent pressure and throttle pressure according to the throttle opening θ of the carburetor 102, and an output side. a torque ratio valve 66 that operates in conjunction with the movable flange 322 of the pulley 32 and supplies line pressure to the detent valve 64 in accordance with the amount of displacement of the movable flange 322, and discharges pressure from the output hydraulic pressure feedback oil passage 9 provided in the throttle valve 65;
and a regulator valve 61 that regulates the oil pressure supplied from the oil pressure source 50 and supplies it to various parts of the oil pressure adjustment device 60 as line pressure. A hydraulic source 50 supplies hydraulic oil pumped up from an oil strainer 51 by a pump 52 driven by an engine to an oil passage 1 to which a relief valve 53 is attached.
1 and is supplied to the regulator valve 61. As shown in FIG. 3, the manual valve 62 has a spool 621 which is set to P, R, N, D, L in accordance with the shift positions P, R, N, D, L of the shift lever provided at the driver's seat.
It is set at each position D and L, and connects the oil passage 1 to which line pressure is supplied and the output oil passages 3 to 5 as shown in the table.

[Table] In the table, 〇 indicates the connection status with oil path 1,
× indicates that the oil passages 3 to 5 are in a discharged pressure state. The regulator valve 61 includes a spool 611 and a regulator valve plunger 612 that controls the spool 611 by inputting detent pressure and throttle pressure. The line pressure is output from the output port 616 to the oil passage 1. Oil is supplied from the port 614 through the oil passage 12 to the fluid coupling, oil cooler, and parts requiring lubrication. The detent valve 64 is linked to and interlocks with the throttle opening θ of the rear valve of the carburetor 102.
It is equipped with a spool 641 that moves as shown in the figure, and when the throttle opening degree is 0≦θ≦ _θ1 , the detent pressure is connected to the oil passage 5 and the input port 616' provided in the regulator valve 61 as shown in FIG. 4A. When θ ₁ <θ≦100%, the oil passage 7 and the detent valve 64 are connected to each other as shown in FIG. 4B.
and the oil passage 6 which communicates with the torque ratio valve 66. Note that the spool 641 may be linked and operated in conjunction with the amount of depression of the accelerator pedal. The throttle valve 65 includes a spool 651 which is connected in series with the spool 641 of the detent valve via a spring 645 and has a spring 652 on the other side, and has a throttle opening θ transmitted via the spool 641 and the spring 645.
By the action of the spool 651 that moves in accordance with the fluctuation of Outputs pressure. Spool 651
The output hydraulic pressure is branched from the oil passage 8 and sent to a land 656 and a land 657 having a larger pressure receiving area than the land 656 via output oil pressure feedback oil passages 9 and 10 provided with orifices 654 and 655, respectively. I am receiving feedback. The torque ratio valve 66 includes a spool 662 linked to the movable flange 322 of the output pulley 32 via a connecting rod.
The amount of movement L is l ₃ ≦L≦l ₄ (torque ratio T is t ₂ ≧T≧t ₁ )
In this case, as shown in FIG. 5A, the spool 662 is located on the left side in the drawing, and closes the input port 664 connected to the output oil pressure feedback oil passage 9 provided in the throttle valve 65, and also closes the input port 664 connected to the output oil pressure feedback oil passage 9 provided in the throttle valve 65. The output oil passage 6 is communicated with the drain port 665 to discharge pressure. When the moving amount L of the movable flange 322 is l ₂ ≦L≦l ₃ (t ₃ ≧T>t ₂ ), Fig. 5B
As shown in FIG.
66, and the oil passage 9 is depressurized. When the amount of movement L is 0≦L≦l ₂ (t ₄ ≧T>t ₃ ), the spool 662 is located on the right side of the figure as shown in FIG. The oil passage 6 is in communication with the oil passage 6, and line pressure is supplied to the oil passage 6. The spool 662 slides in conjunction with the movable flange 322 of the rotating output pulley 32, but as shown in FIG. Since it has a structure that does not hinder the movement of the movable flange, it is possible to prevent wear and the like of sliding parts that have a large relative speed. The shift control mechanism 70 has a spring 71 on one side.
A shift control valve 71 equipped with a spool 712 that receives line pressure from an oil chamber 713 provided at the other end, an orifice 72 provided in the oil passage 1 that supplies line pressure to the oil chamber 713, and the orifice 7
2 and an oil chamber 713, and a solenoid valve 74 that is controlled by an electric control circuit to be described later and adjusts the oil pressure in the oil chamber 713. Solenoid valve 74
operates and opens the drain port 741 and the oil chamber 71
3, the spool 712 of the shift control valve 71 is moved to the left in the figure by the action of the spring 711, and the oil passage connected to the hydraulic servo 49 that operates the multi-disc clutch 45 of the planetary gear transmission 40 is released. 13 and an oil passage 14 communicating with a hydraulic servo 48 for operating the multi-disc brake 42 are connected to drain ports 714 and 715, respectively, to discharge pressure, thereby releasing the multi-disc clutch 45 or the multi-disc brake 42. When the solenoid valve 74 is not operating, the drain port 741 is closed and the spool 71
2 is the line pressure supplied to the oil chamber 713 and is located on the right side in the figure, and connects the oil passages 3 and 4 to the oil passages 13 and 14, respectively, and connects the multi-disc brake 4.
2 or multiple plate clutch 45 is engaged. In this embodiment, the oil chamber 7 feeds back the output oil pressure of the oil passages 13 and 14 to the shift control valve 71.
17 and an oil chamber 716 are provided to alleviate the rise of output hydraulic pressure and to reduce the rise of the output hydraulic pressure, and
2. This prevents shock when engaged. The torque ratio control device 80 includes a torque ratio control valve 81, orifices 82 and 83, a downshift solenoid 84, and an upshift solenoid 8.
Consists of 5. The torque ratio control valve 81 is connected to the oil passage 1 through a spool 812 having a spring 811 on one side and orifices 82 and 83, respectively.
oil chambers 815 and 816 at both ends to which line pressure is supplied, an input port 817 that communicates with oil passage 1 to which line pressure is supplied, and whose opening area increases or decreases according to the movement of the spool 812, and a V-belt type stepless An output port 81 that communicates with the hydraulic servo 313 of the input pulley 31 of the transmission 30 via the oil path 2
8, a drain port 814 that evacuates the oil chamber 816 as the spool 812 moves, and a drain port 813 that evacuates the oil chamber 815 as the spool 812 moves. The downshift solenoid 84 and the upshift solenoid 85 are attached to an oil chamber 815 and an oil chamber 816, respectively, of the torque ratio control valve 81, and both are operated by the output of an electric control circuit to be described later. The pressure in the oil chamber 816 is evacuated. FIG. 6 shows the solenoid valve 74 of the shift control mechanism 70 and the downshift solenoid 84 of the torque ratio control device 80 in the hydraulic control circuit shown in FIG.
The configuration of an electric control circuit 90 that controls the upshift solenoid 85 is also shown. 901 is a shift lever switch that detects whether the shift lever is shifted to P, R, N, D, or L; 902 is a rotation speed sensor that detects the rotation speed of the input pulley 31; 903 is a vehicle speed sensor; 904 is a throttle sensor that detects the throttle opening of the carburetor or the amount of depression of the accelerator pedal; 905 is a speed detection processing circuit that converts the output of the rotational speed sensor 902 into voltage; 906
907 is a throttle opening detection processing circuit that converts the output of the throttle sensor 904 into voltage; 908 to 911 are input interfaces for each sensor; and 912 is a central processing circuit. Device (CPU), 913
914 is a read-only memory (ROM) that stores programs for controlling the solenoid valves 74, 84, and 85 and data necessary for control, and 914 is a random access memory (ROM) that temporarily stores input data and parameters necessary for control. RAM), 91
5 is a clock, 916 is an output interface,
A solenoid output driver 917 converts the output of the output interface 916 into operating outputs of the upshift solenoid 85, the downshift solenoid 84, and the shift control solenoid 74. Input interfaces 908 to 911
A data bus 91 is connected between the CPU 912, ROM 913, RAM 914, and output interface 916.
8 and an address bus 919. Next, torque ratio valve 66, detent valve 6
4. The operation of the hydraulic pressure adjusting device 60 of this embodiment, which is composed of the throttle valve 65, the manual valve 62, and the regulator valve 61, will be explained. The hydraulic oil supplied to the hydraulic control circuit is supplied from a pump 52 driven by the engine, and if the line pressure is high, power consumption by the pump 52 increases accordingly. Therefore, in order to run a vehicle with low fuel consumption, it is necessary to bring the line pressure supplied to the hydraulic control circuit close to the minimum necessary, and in a continuously variable transmission, this line pressure is applied to the input pulley 3.
Each hydraulic servo of the V-belt 1 and the output pulley 32 is defined by a hydraulic pressure that allows torque to be transmitted without causing the V-belt 33 to slip. The solid line in FIG. 7 shows the minimum line pressure necessary for a change in the torque ratio T between the input and output shafts when the engine is operated in a state that provides the best fuel efficiency, using the throttle opening θ as a parameter. When the vehicle is started, it is impossible to operate the engine at the best fuel efficiency within the range of torque ratios that can be achieved by both pulleys, so the characteristic curve for the best fuel efficiency shown by the solid line above is shown by the dotted line.
It is desirable that the line pressure be approximately 20% larger as shown by the broken line, and during engine braking, it is also desirable to have a line pressure characteristic that is higher than that shown by the dashed line even when the throttle opening θ=0. In this embodiment, the line pressure, which is the output of the regulator valve 61, is controlled by the hydraulic pressure adjustment device 60.
Shift position of manual valve 62 (L, D, N,
R, P), throttle opening θ, and the torque ratio of both pulleys (torque ratio between input and output shafts) are adjusted as follows. Position D As shown in Table 1, in the manual valve 62, only the oil passage 3 communicates with the oil passage 1, and the oil passage 4 and the oil passage 5 are discharged. At this time, in the shift control mechanism 70, the shift control solenoid 74 is activated.
When line pressure is supplied to the oil chamber 713 in the OFF state, the spool 712 is positioned to the right, so that the oil passage 3 and the oil passage 13 are connected, and the line pressure supplied to the oil passage 3 is acts on the hydraulic servo 49 of the multi-plate clutch 45 for forward movement through the oil passage 13, and the vehicle becomes ready to move forward. (1) When the torque ratio T is t ₁ ≦T≦t ₂ . As shown in FIG. 5A, the torque ratio valve 66 is
Close port 663 connected to oil passage 1, and close oil passage 6.
is communicated with the drain port 665 to exhaust pressure. As a result, detent pressure (equal to line pressure) is not generated in the oil passage 7 regardless of the throttle opening degree θ. Further, the throttle valve 65 is connected to the port 6 of the torque ratio valve 66 which communicates with the oil passage 9.
64 is closed, and the spool 651 receives feedback pressure from the land 657 in addition to the land 656. Therefore, the throttle pressure having the characteristic shown in FIG. output to the regulator valve plunger 612. As a result, the line pressure output from the regulating valve 61 is adjusted to
The result will be as shown in E of the figure. (2) When the torque ratio T is t ₂ <T≦t ₃ . As shown in FIG. 5B, the torque ratio valve 66 closes the port 663 and allows the oil passage 9 and the drain port 666 to communicate with each other. In addition, the pressure in the oil passage 6 is exhausted through the port 665. Therefore, no detent pressure is generated, and the throttle pressure increases by the amount that the pressure in the oil passage 9 is exhausted and the feedback pressure is no longer applied to the land 657 of the spool 651.
This is expressed by the characteristic curve shown in FIG. 8D. The line pressure at this time has the characteristics shown in area R in FIG. 9 and area G in FIG. (3) When the torque ratio T is t ₃ <T≦t ₄ . As shown in FIG. 5C, the pressure in the oil passage 9 is exhausted from the drain port 666, and therefore the throttle pressure is expressed by D in FIG. 8 as in (2) above. However, since the port 663 opens and the oil passage 1 and the oil passage 6 communicate with each other, the throttle opening θ is within the range of 0≦θ≦θ ₁ %, and the spool 64 of the detent valve 64
1 is on the left side in the figure as shown in FIG.
However, the throttle opening θ is θ ₁
When %<θ≦100%, the spool 641 moves as shown in FIG. 4B, and the oil passage 6 and the oil passage 7 communicate with each other, and detent pressure is generated in the oil passage 7. As a result, the line pressure has a characteristic that changes stepwise at θ=θ ₁ %, as shown in area 2 of FIG. 9 and area 1 of FIG. 10. L position The oil passage 5 communicates with the oil passage 1 at the manual valve 62. Oil passage 3 and oil passage 4 are the same as the D position. (1) When the torque ratio T is t ₁ ≦T≦t ₂ . When the throttle opening θ is 0≦θ≦θ ₁ %, the oil passage 5 and the oil passage 7 communicate with each other at the detent valve 64, and detent pressure is generated to push up the throttle plunger and generate high line pressure.
When θ ₁ %<θ≦100%, the pressure in the oil passage 7 is exhausted through the oil passage 6 and the drain port 665 of the torque ratio valve as shown in FIG. 4B, and detent pressure is not generated, and the throttle pressure is is the same as for the D position. Therefore, the line pressure has the characteristics shown in FIG. (2) When the torque ratio T is t ₂ <T≦t ₃ . The difference from (1) above is that in the torque ratio valve 66, the oil passage 9 communicates with the drain port 666 to exhaust pressure, and the throttle pressure output from the throttle valve 65 to the adjustment valve 61 via the oil passage 8 increases. In particular, as a result, the line pressure is expressed by a characteristic curve as shown in FIG. (3) When the torque ratio T is t ₃ <T≦T ₄ . Oil passage 6 and oil passage 1 are connected by the torque ratio valve 66.
and the oil passage 9 is connected to the drain port 666.
Pressure is being released from the Since line pressure is supplied to both the oil passage 6 and the oil passage 5, the detent valve 64 outputs the detent pressure regardless of the throttle opening, and inputs the detent pressure and the same throttle pressure as in (2) above. The regulating valve 61 outputs the line pressure shown in FIG. R position As shown in the table, the oil passage 4 and the oil passage 5 communicate with the oil passage 1 in the manual valve 62, and the oil passage 3 is discharged. At this time, in the shift control mechanism 70, if the shift control solenoid 74 is in the OFF state and line pressure is being supplied to the oil chamber 713, the spool 712 is positioned to the right, so that the oil passage 4 is connected to the oil passage 14. The line pressure supplied to the oil passage 4 is supplied to the hydraulic servo 48 of the reverse multi-disc brake 42 through the oil passage 14, and the vehicle enters the reverse traveling state. Furthermore, since the line pressure is guided to the oil passage 5, the line pressure has the same characteristics as in the L position. At the R position, the torque ratio T in the V-belt continuously variable transmission 30 is set to the maximum, T= _t4 . Therefore, there is no need to perform a speed change (deceleration) within the planetary gear transmission 40, but according to this embodiment,
Even when the torque ratio T is changed in the R position, the line pressure can be controlled in the same way as in the L position. P position and N position Oil passages 3, 4 and 5 in manual valve 62
Both are exhausted, and since the oil passage 5 is exhausted, the line pressure, which is the output of the regulator valve 61, is the same as at the D position. When the manual valve 62 is shifted to the D, N, and P shift positions in this line pressure adjustment, the line pressure when the torque ratio T is in the range of t ₃ < T ≦ t ₄ is determined by the characteristics shown in Fig. 10. The reason for setting the throttle opening θ as low as ₁ % or less as shown in curve 2 is because if the line pressure is set high in operating conditions such as idling where the throttle opening θ is small and the pump discharge amount is low, the oil temperature will be high. This is because when there is a large amount of oil leaking from various parts of the hydraulic circuit, it becomes difficult to maintain line pressure, and furthermore, the oil temperature further increases due to a decrease in the amount of oil supplied to the oil cooler, which is likely to cause trouble. Further, when the manual valve 62 is shifted to the L and R shift positions, the torque ratio T is in the range of t ₁ ≦T≦t ₂ and the throttle opening is θ
The reason why the line pressure is set high under operating conditions where θ ₁ % or less is because relatively high oil pressure is required during engine braking even when the throttle opening is low. The required oil pressure at that time is shown by a dashed line in FIG. In this way, as shown in FIG. 9, by bringing the line pressure close to the minimum necessary oil pressure shown in FIG. 7, the power loss caused by the pump 52 can be reduced, thereby improving fuel efficiency and fuel consumption rate. Next, the operations of the shift control mechanism 70 and the torque ratio control device 80 controlled by the electric control circuit 90 described in FIG. 6 will be explained with reference to the program flowcharts shown in FIGS. 18 to 23. In this embodiment, an example is shown in which the electric control circuit 90 controls the input pulley rotation speed N to obtain the best fuel efficiency at each throttle opening θ. Generally, when operating an engine in a state with the best fuel efficiency, the engine is operated according to the best fuel efficiency power line, which is a broken line shown in the graph of FIG. In FIG. 12, the horizontal axis shows the engine rotation speed (rpm), the vertical axis shows the torque ratio (Kg·m) of the engine output shaft, and the best fuel efficiency power line is obtained as follows. In other words, from the engine's equal fuel consumption rate curve (in g/ps/h) shown by the solid line in Figure 12 and the equal horsepower curve (in ps) shown by the two-dot chain line, the fuel at point A in the figure can be calculated. Assuming that the consumption rate is Q (g/ps·h) and the horsepower is P (ps), at point A, fuel will be consumed per hour by S=Q×P (g/h). By determining the fuel consumption per hour S at all points on each equal horsepower curve, the point where S is the minimum on each equal horsepower curve can be determined, and by connecting these points, the best value for each horsepower can be determined. The best fuel efficiency power line indicating the engine operating state resulting in fuel efficiency can be obtained. However, when the engine 100 and the fluid coupling 21, which is a fluid transmission mechanism, are combined as in this embodiment, the engine output performance curves at each throttle opening θ shown in FIG. , 14th
The fluid coupling performance curve shown in the figure and the first
As shown in FIG. 16, the best fuel efficiency fluid coupling output line can be found on the fluid coupling output performance curve from the engine equivalent fuel consumption rate curve shown in FIG. FIG. 17 shows the best fuel efficiency fluid coupling output line shown in FIG. 16 replaced by the relationship between throttle opening and fluid coupling output rotation speed. This fluid coupling output rotation speed directly becomes the input pulley rotation speed in the continuously variable transmission of this embodiment. In the continuously variable transmission of this embodiment, the speed is changed between the input pulley 31 and the output pulley 32 based on the best fuel economy input pulley rotation speed obtained as described above and the detected actual input pulley rotation speed. Control the ratio. The torque ratio control device 80 controls the increase or decrease in the gear ratio between the input and output pulleys by comparing the rotational speed of the input pulley with the best fuel efficiency obtained in FIG. 17 and the actual rotational speed of the input pulley. Control device 80
This is done by actuating two solenoid valves 84 and 85 provided in the input side, so that the actual input pulley rotation speed matches the input pulley rotation speed for the best fuel efficiency. FIG. 18 shows an overall flowchart of input side pulley rotation speed control. After the throttle opening θ is read by the throttle sensor 904 (921), the shift lever position is determined by the shift lever switch 901 (922). As a result of the determination, if the shift lever is in the P position or N position, both the solenoid valves 84 and 85 are turned off by the P position or N position processing subroutine shown in FIG. 19 (931), and the P or N state is transferred to the RAM 914. (932) As a result, a neutral state of the input pulley 31 is obtained. When the shift lever changes from P position or N position to R position, and from N position to D position, N-R respectively.
Shift shock control processing is performed to alleviate shift shock caused by shift and N-D shift (940, 950). The shift shock control uses a shift control solenoid valve 74 shown in FIG. 20 to generate pulses whose pulse widths gradually become smaller.
(hereinafter referred to as duty control). By duty-controlling the shift control solenoid valve 74 in this way, the oil chamber 71 of the shift control valve 71
3, a hydraulic pressure P _s is generated that is adjusted in accordance with the duty. The shift control mechanism 70 includes the electric control circuit 9 described above.
By the action of the solenoid valve 74 controlled by the output of 0, the timing of supplying and discharging the hydraulic pressure to the hydraulic servos 48 and 49 of the planetary gear transmission 40 is adjusted to prevent shock during shifting, and the pressure limiting valve Hydraulic servo 48 and 4 due to the action of 73
It has the function of keeping the upper limit of the oil pressure supplied to 9 below a set value, and limits the engagement pressure of the clutch and brake. When relaxing the engagement shock during N-D shift and N-R shift, the rise of the hydraulic pressure P _b or P _c supplied to the hydraulic servo 48 or hydraulic servo 49 is controlled as shown in the hydraulic characteristic curve shown in FIG. 24B. Then, in the figure, the engagement of the multi-disc clutch 45 or the multi-disc brake 42 between AC is completed. The solenoid valve 7 for controlling the hydraulic pressure supplied to the hydraulic servo 48 or 49 in this way
FIG. 25 shows the relationship between the duty (%) of No. 4 and the solenoid pressure P _s generated in the oil chamber 713 by the operation of the solenoid valve 74. Duty (%) is given by the following formula. Duty (%) = Solenoid ON time in one cycle/Solenoid operating time x 100 The solenoid pressure shown in Fig. 25 is amplified by the shift control valve 71, and the hydraulic pressure P _b shown in Fig. 26 is supplied to the hydraulic servo 48 or 49. Or P _c is obtained. In this embodiment, as shown in FIG. 24A, the pressure receiving area of the land provided on the spool 712 of the shift control valve 71 is S ₁ , S ₁ , S ₁ , S ₂ and the elastic force of the spring 711 in order from the left side in the figure. Assuming that F _s1 is F s1 and the oil pressure of the oil chamber 713 is P _s , the hydraulic pressure P c supplied to the hydraulic servo 49 of the multi-disc clutch 45 that is engaged during forward movement and the hydraulic servo 48 of the multi-disc brake 42 that is engaged during reverse movement is P _c and P _b are given as follows from the equations 1 and 2, which are hydraulic equilibrium equations for the shift control valve 71, respectively. When moving forward P _s × S ₁ = P _c × S ₂ + F _s1 P _c = S ₁ /S ₂ P _s −F _s1 /S ₂ When moving backward P _s × S ₁ = P _b × (S ₁ − S ₂ ) + F _s1 P _b = S ₁ /S ₁ -S ₂ P _s -F _s1 /S ₁ -S ₂ In addition, the pressure receiving area of the valve body 731 inserted in the pressure limiting valve 73 is S _{3 , and the pressure receiving area of the valve body 731 is S 3} . body 73
The elastic force of the spring 732 installed behind 1 is F _s2
Then, the pressure limiting valve 73 operates at the maximum pressure p limit of P _s according to the hydraulically balanced equation. p limit×S ₃ =F _s2 p limit=F _s2 /S ₃ At this time, the maximum pressures p _c limit and p _b limit of P _c and P _b are limited according to the formulas 1 and 2. When moving forward p _c limit = S ₁ / S ₂ p limit - F _s1 / S ₂ When moving backward p _b limit = S ₁ / S ₁ - S ₂ p limit - F _s1 / S ₁ - _{S 2}
Returning to FIG. 18, following the N-D shift shock control processing 950, the input pulley rotation speed sensor 902 reads the actual input pulley rotation speed N (923), and then the throttle opening is adjusted. Determine whether θ is 0 or not (924), and θ≠
When it is 0, the best fuel economy input side pulley rotation speed N ^* corresponding to the throttle opening degree θ shown in FIG. 17, which is stored in the ROM 913 as data in advance according to the subroutine shown in FIG. 21, is set (960).
Input pulley rotation speed corresponding to throttle opening
N ^* Set the data storage address (961),
Read N ^* data from the set address (962), and use the read N ^* data for data storage.
It is temporarily stored in RAM 914 (963). Next, compare the actual input pulley rotation speed N and the best fuel efficiency input pulley rotation speed N ^* (927), and
When <N ^* , a command to operate the downshift solenoid valve 84 is issued (928), when N>N ^* , a command to operate the upshift solenoid valve 85 is issued (929), and when N=N ^* , both solenoids are activated. An OFF command for valves 84 and 85 is issued (920). When the throttle is fully closed when θ=0, it is determined whether the shift lever is set to the D position or the L position to determine whether engine braking is necessary (926), and engine braking is applied as necessary. Perform processing 970 or 980. As shown in FIG. 22, the engine brake processing 970 at the D position reads the vehicle speed V using the vehicle speed sensor 903 (971), calculates the acceleration α at that point (972), and then calculates the acceleration α.
It is determined whether or not the acceleration A is appropriate for the vehicle speed (973). When α>A, the downshift control 974 is performed, so N ^* is set to a value larger than N, and then the return is made. When α≦A, N ^* is the best fuel consumption input pulley rotation corresponding to throttle opening 0. Returns after setting the number N ^* (975). The relationship between vehicle speed and appropriate acceleration A is determined by experiment or calculation for each vehicle, and is shown in the graph B in FIG. 22. In the engine brake processing 980 at the L position, the second
As shown in FIG. 3, after reading the vehicle speed V (981), a calculation is performed to calculate the torque ratio T from the following equation from the vehicle speed V and the input pulley rotation speed N (982). T=(N/V)×k k is the reduction gear mechanism 2 inside the transmission
3, the final reduction ratio of the vehicle, the tire radius, etc. Next, it is determined whether the current torque ratio T is larger than the torque ratio T ^* that provides safe and appropriate engine braking for the vehicle speed V (983), and if T<T ^* , the downshift is performed. N ^* is set to a value larger than N so as to be executed (984), and when T≧T ^* , N ^* is set to a value equal to N (985), and the process returns. The torque ratio T ^* that provides safe and appropriate engine braking for each vehicle speed is determined by experiment or calculation for each vehicle, and is shown in the graph of FIG. 23B. Next, the operation of the torque ratio control device 80 will be explained with reference to FIG. 27. When traveling at a constant speed, as shown in FIG. 27A, the solenoid valves 84 and 85 controlled by the output of the electric control circuit are
It is turned off. As a result, the oil pressure P ₁ in the oil chamber 816 is the line pressure, and the oil pressure P ₂ in the oil chamber 815 is also the line pressure when the spool 812 is on the right side in the figure. Spool 812 is spring 81
Since there is a pressing force P ₃ due to 1, it is moved to the left in the figure. The spool 812 is moved to the left and the oil chamber 81
5 and the drain port 813 communicate with each other, the pressure P ₂ is exhausted, so the spool 812 is moved to the right in the figure by the oil pressure P ₁ in the oil chamber 816. Spool 8
When 12 is moved to the right, the drain port 813
will be closed. Therefore, the spool 812 is connected to the drain port 81 in this case, as shown in FIG.
By providing a flat notch 812b at the land edge between the spool 812 and the spool 812, it becomes possible to more stably hold the spool 812 at an intermediate equilibrium point as shown in FIG. 27A. In this state, the oil passage 2 is closed,
The hydraulic pressure of the hydraulic servo 313 of the input pulley 31 is
The line pressure applied to the hydraulic servo 323 of the output pulley 32 causes it to be compressed via the V-belt 33, resulting in equilibrium with the hydraulic pressure of the hydraulic servo 323. Actually, since there is oil leakage in the oil passage 2 as well, the input pulley 31 is gradually expanded and the torque ratio T changes in the direction of increasing. Therefore, as shown in FIG. 27A, in the position where the spool 812 is balanced, the drain port 814
A flat notch 812a is provided at the land edge with the spool 812 so that the oil passage 1 is closed and the oil passage 1 is slightly open, thereby compensating for oil leakage in the oil passage 2. Furthermore, it is clear that the same function can be achieved by connecting oil passages 1 and 2 with an oil passage 822 having an orifice 821 instead of the notch 812a as shown in FIG. During an upshift, the solenoid valve 85 is turned ON by the output of the electric control circuit as shown in FIG. 27B. As a result, the pressure in the oil chamber 816 is evacuated, so the spool 812 is moved to the left in the figure.As the spool 812 moves, the pressure in the oil chamber 815 is also evacuated from the drain port 813, but due to the action of the spring 811, the spool 812
12 is set at the left end in the figure. In this state, the line pressure of oil passage 1 is at port 818.
Hydraulic servo 31
3 increases, the input pulley 31 operates in the closing direction, and the torque ratio T decreases. Therefore, by controlling the ON time of the solenoid valve 85 as necessary, the upshift is performed by reducing the torque ratio by a desired amount. During a downshift, as shown in FIG. 27C, the solenoid valve 84 is turned on by the output of the electric control circuit, and the pressure in the oil chamber 815 is evacuated. The spool 812 is moved to the right in the figure by the line pressure of the oil chamber 816, the oil passage 2 is communicated with the drain port 814 and the pressure is discharged, and the input pulley 31 is operated in the expanding direction to increase the torque ratio.
By controlling the ON time of the solenoid valve 84 in this way, the torque ratio is increased and a downshift is performed. As described above, the input side (drive side) pulley 31
The hydraulic servo 312 is connected to the torque ratio control valve 81.
The output hydraulic pressure is supplied, and the line pressure is guided to the hydraulic servo 323 of the output side (driven side) pulley 32, and the hydraulic pressure of the input side hydraulic servo 312 is set as P _i ,
If the oil pressure of the output side hydraulic servo 322 is P _p ,
P _p /P _i has a characteristic as shown in the graph of FIG. 28 with respect to the torque ratio T. For example, the throttle opening θ
= 50%, and when driving with torque ratio T = 1.5 (point a in the figure), release the accelerator and set θ = 30%. If P _p /P _i is maintained as it is, torque ratio T = It moves to point b in the figure at 0.87, and conversely the torque ratio T=
When maintaining the state of 1.5, the value of P _p /P _i is increased by the output of the torque ratio control device 80 that controls the input pulley and changed to the value at point c in the figure. By controlling the value of P _p /P _i as necessary in this way, it is possible to set an arbitrary torque ratio corresponding to any load condition.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a V-belt type continuously variable transmission for vehicles, Fig. 2 is a hydraulic control circuit diagram of a continuously variable transmission showing one embodiment of the present invention, and Fig. 3 explains the operation of a manual valve. Figure 4 is a diagram for explaining the operation of the detent valve and throttle valve.
The figure is a diagram to explain the operation of the torque ratio valve.
Figure 6 is a diagram showing the configuration of the electric control circuit, Figure 7 is a diagram showing the required line pressure characteristics of the hydraulic control circuit, Figure 8 is a diagram showing the characteristics of the throttle pressure, Figures 9, 10, and 11. 12 is a diagram showing the line pressure characteristics obtained by the control device of the present invention, FIG. 12 is a diagram showing the best fuel consumption power line of the engine, FIG. 13 is a diagram showing the engine output performance characteristics, and FIG. 14 is a diagram showing the fluid transmission. Figure 15 is a diagram showing the performance curve of the mechanism, Figure 15 is a diagram showing the equal fuel consumption rate curve of the engine, Figure 16 is a diagram showing the best fuel consumption fluid coupling output curve, and Figure 17 is a diagram showing the best fuel efficiency fluid coupling output rotation speed. Figures showing the characteristics, Figures 18, 19, 21, 22A, and 23A are diagrams for explaining the flow of processing in the electric control circuit, and Figure 20 shows the action of the solenoid valve. Figure 22B is a diagram showing the set acceleration, Figure 23B is a diagram showing the set torque ratio, Figure 24A is a diagram explaining the operation of the shift control mechanism, Figure 24 B is a diagram showing the characteristics of the oil pressure supplied to the hydraulic servo on the input side and the output side, FIG. 25 is a diagram showing the characteristics of the solenoid pressure, FIG. 26 is a diagram showing the characteristics of the output oil pressure of the shift control valve,
Fig. 7 is a diagram for explaining the operation of the torque ratio control device, Fig. 28 is a diagram showing the relationship between the torque ratio and the pressure ratio of the input/output side hydraulic servo, and Fig. 29 is a diagram showing another implementation of the torque ratio control device. FIG. 30, a configuration diagram showing an example, is a schematic diagram of a conventional V-belt type continuously variable transmission for a vehicle. 214...Input shaft, 26...Output shaft, 31...
Input side pulley, 32... Output side pulley, 33...
V-belt, 30...Continuously variable transmission, 90...Electric control circuit, 61...Regulator valve, 64...Detent valve, 65...Throttle valve, 66...Torque ratio valve, 313, 323...Hydraulic servo ,7
1...Shift control valve, 81...Torque ratio control valve.

Claims (1)

[Claims] 1. Attached to the input shaft and the output shaft, respectively,
A vehicle that consists of an input-side pulley and an output-side pulley with variable effective diameters, and a drive band stretched between these pulleys, and controls the torque ratio between the input and output shafts by adjusting the effective diameter of the pulleys using hydraulic pressure. In a V-belt type continuously variable transmission for use, a hydraulic source, a pressure regulating device that regulates the pressure of hydraulic oil from the hydraulic source to generate line pressure, and a pressure regulating device that is supplied with the line pressure and controls the drive band according to the line pressure. A hydraulic servo that generates clamping force,
1. A hydraulic control device for a V-belt continuously variable transmission for a vehicle, comprising a step-down means for setting the line pressure low when the throttle opening is below a predetermined value and the torque ratio is above a predetermined value. 2. The pressure reducing means includes a torque ratio valve that generates hydraulic pressure according to the torque ratio and supplies the hydraulic pressure to the pressure regulating device so as to adjust the line pressure, and a torque ratio valve that generates hydraulic pressure according to the torque ratio and supplies the hydraulic pressure to the pressure regulating device, and a torque ratio valve that generates hydraulic pressure according to the torque ratio. The V-belt type continuously variable transmission for a vehicle according to claim 1, further comprising a suppressing means for suppressing the hydraulic pressure adjustment effect on the pressure regulating device according to the torque ratio when the torque ratio is greater than or equal to the torque ratio. Machine hydraulic control device. 3. The suppressing means shuts off an oil passage that supplies oil pressure according to the torque ratio to the pressure regulating device when the torque ratio is greater than or equal to a predetermined value, and shuts off the oil passage when the throttle opening is less than or equal to a predetermined value. The vehicle V according to claim 2, further comprising a valve body.
Hydraulic control device for belt type continuously variable transmission.