JPH0238824B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a hydraulic automatic control device for a continuously variable transmission for a vehicle using a V-belt type continuously variable transmission. [Prior Art] Conventionally, a V-belt type continuously variable transmission can be suitably used as a continuously variable transmission for a vehicle in combination with a forward/reverse switching mechanism and a fluid coupling such as a torque converter. , throttle opening, etc. are detected and input to a control circuit, and the control circuit controls the torque ratio of the continuously variable transmission. In general, when operating the engine in a preset state for each throttle opening, the hydraulic pressure required increases as the throttle opening increases, so the line pressure controlled by the hydraulic control device is It is desirable to change the throttle opening degree as a parameter so that the hydraulic pressure approaches the minimum hydraulic pressure required by the hydraulic servo mechanism of the V-belt continuously variable transmission. Furthermore, it is desirable that the oil pressure supplied to the hydraulic servo of the continuously variable transmission be controlled in accordance with vehicle running conditions such as vehicle speed and throttle opening. However, in order to achieve accurate control using a conventional control device, the number of parts increases, the occurrence rate of failure increases accordingly, and the cost also increases. [Problems to be Solved by the Invention] Therefore, the present invention provides a vehicle-use product that can be controlled according to vehicle running conditions, is less likely to malfunction without increasing the number of parts, and can be manufactured at low cost. The purpose of this invention is to provide a control device for a gear transmission. [Means for solving the problem] Therefore, in order to solve the above problem, an input side pulley and an output side pulley, which are attached to the input shaft and the output shaft respectively, and whose effective diameters are variable by hydraulic pressure, and these pulleys have been developed. In a control device for a continuously variable transmission for a vehicle that has a V-belt that transmits power between the two, a hydraulic source, a regulator valve that regulates the hydraulic pressure from the hydraulic source to line pressure, and a governor pressure that outputs a governor pressure that corresponds to the pulley rotation speed. The throttle valve includes a governor pressure and a spring that is pressed by displacement of a throttle cam corresponding to the throttle opening, and a torque ratio control valve that outputs hydraulic pressure for operating the input pulley or the output pulley. The valve outputs a hydraulic pressure corresponding to the throttle opening degree to the regulator valve, and the regulator valve inputs the hydraulic pressure corresponding to the throttle opening degree, thereby adjusting the line pressure to the hydraulic pressure corresponding to the throttle opening degree, The torque ratio control valve has a spool that receives the load of the spring on one side and receives governor pressure on the other side to bias the load of the spring, and has a spool that receives the governor pressure so as to bias the load of the spring on one side. The corresponding line pressure is controlled by the spool and has a structure that controls either the input pulley or the output pulley. [Operations and Effects] The present invention sets the line pressure to hydraulic pressure corresponding to the throttle opening, and the torque ratio control valve receives a spring load corresponding to the throttle opening on one side, and applies the spring load on the other side. The line pressure corresponding to the throttle opening input to the torque ratio control valve is controlled by the spool and controls either the input pulley or the output pulley. Since the structure is such that the pressure corresponding to the throttle opening controls the line pressure, it also acts on the torque ratio control valve that controls either the input pulley or the output pulley, increasing the number of parts. The present invention has the advantage that it is possible to perform control according to the vehicle running state without any problems, and it can be manufactured at low cost. Next, the present invention will be explained based on embodiments shown in the drawings. FIG. 1 schematically shows a continuously variable transmission for a vehicle using a V-belt type continuously variable transmission. 100 is the engine, 21 is the output shaft 1 of the engine
01 is a fluid coupling connected to it, 23 is a reduction gear mechanism connected to a differential gear 22, and 30 is an output shaft 2 of the fluid coupling.
V-belt type continuously variable transmission with 14 as the input shaft, 24
40 is a governor valve mounted on the output shaft 214 of the fluid coupling so as to rotate together with the output shaft;
is a planetary gear transmission with a forward/reverse switching mechanism. The fluid coupling 21 includes a pump impeller 211 and a fluid coupling output shaft 21.
The turbine runner 212 is a well-known type consisting of a turbine runner 212 connected to a turbine runner 212. Note that a fluid torque converter or a mechanical clutch may be used instead 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 an input-side pulley 31 consisting of a hydraulic cylinder 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 opposite to the fixed flange 321 to form a V-shaped space.
2, an output pulley 32 consisting of a hydraulic cylinder 323 that drives the movable flange 322, and a V-belt 33 connecting the input pulley 31 and the output pulley 32. . The above input pulley 31 and output pulley 32
The amount of displacement 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 a 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 cylinder 313 is approximately twice the pressure receiving area of the output side hydraulic cylinder 323, and the hydraulic pressure applied to the hydraulic cylinder 313 is equal to or equal to the hydraulic pressure applied to the hydraulic cylinder 323. By adjusting within a small range, the pressing force of the movable flange on the input side can be made larger or smaller than the pressing force of the movable flange on the output side. This hydraulic cylinder 31
The increase in the pressure-receiving area of No. 3 can be achieved by increasing the diameter of the hydraulic cylinder or by employing a piston having a double pressure-receiving surface in the hydraulic cylinder as shown in FIG. 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; Furthermore, it is composed of a planetary gear 46 connected to a second intermediate shaft 47 that is the output shaft of the planetary gear transmission 40, a hydraulic cylinder 48 that operates a multi-disc brake 42, and a hydraulic cylinder 49 that operates a multi-disc clutch 45. . This planetary gear transmission 40 for forward/reverse switching provides a forward gear with a reduction ratio of 1 when the multi-plate clutch 45 is engaged and the multi-disc brake 42 is released; When the plate brake 42 is engaged, it becomes a reverse gear with a reduction ratio of 1.02. This reduction ratio of 1.02 during reversing is smaller than the reduction ratio during reversing of a normal automobile transmission, but in this example, the reduction ratio (for example, 2.4) obtained in a V-belt continuously variable transmission and Since the speed reduction is performed in the speed reduction gear mechanism 23, an appropriate speed 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 3.27:1. FIG. 2 shows a hydraulic control circuit for controlling the continuously variable transmission for a vehicle shown in FIG. The hydraulic control circuit includes a hydraulic power source 50, a manual valve 55 manually operated by a shift lever (not shown), and an input pulley 31 of a V-belt continuously variable transmission.
The governor valve 24 is connected to the governor valve 24, the governor pressure (pressure in the oil passage 2) is regulated by the governor valve 24 according to the rotation of the input pulley 31, and the throttle opening is expressed by the movement of the throttle cam, which will be described later. A torque ratio control valve 60 that adjusts and controls the output hydraulic pressure to the hydraulic cylinder 313 according to the throttle opening, a throttle cam 20 that rotates in proportion to the throttle opening, and a spool 71 that is moved by the cam, and outputs throttle pressure. At the same time, the throttle valve 70 discharges pressure from the output hydraulic pressure of the line pressure control valve (to be described later) according to the throttle opening, and the V-belt continuously variable transmission 30 is supplied according to the torque ratio (or gear ratio). Torque ratio valve 80 outputs throttle pressure as torque ratio pressure, line pressure control valve 90 generates output according to torque ratio and throttle opening, accumulator 27 and check valve 28, clutch 45, which determines the timing of engagement of brake 42. an accumulator 25 and a check valve 29, and the governor valve 2
It consists of 4. The hydraulic power source 50 supplies hydraulic oil pumped up by an oil pump 52 driven by an engine from an oil strainer 51 to a regulator valve 54 through an oil passage 12 to which a relief valve 53 is attached. The annual valve 55 changes the shift positions (ranges) of the shift lever provided on the driver's seat: P (park), R (reverse), N (neutral), D (drive), L.
(low), the spool 551 is P, R, N,
The oil passage 1 and the throttle valve 70 are set at the D and L positions and are supplied with line pressure as shown in Table 1.
The oil passage 3 through which line pressure is supplied is connected to the oil passages 4 to 6 through which the line pressure is distributed to various parts of the hydraulic control circuit.

[Table] In Table 1, ○ indicates that it is in communication with hydraulic pressure 1, △ indicates that it is in communication with hydraulic pressure 3, and × indicates that it is not in communication with any oil path, and each oil path is drained. Indicates that pressure is being applied. In the P and N ranges, line pressure is supplied only to the oil passage 6, and in the D and L ranges, line pressure is generated in the oil passage 4, and the hydraulic pressure supplied from the oil passage 4 via the accumulator 25 and check valve 29 causes the hydraulic cylinder to 49 is activated, the clutch 45 is engaged, and forward travel is obtained. In the R range, instead of the pressure in the oil passage 4 being exhausted and the clutch 45 being released, line pressure is supplied to the oil passage 5 and the brake 42 is engaged, resulting in a reverse running state. Line pressure is supplied to the oil passage 6 in any range, but in the P, N, and D ranges, oil pressure is supplied via the throttle valve 70 and the oil passage 3, and oil is supplied only when the throttle opening is above the set value. Line pressure is supplied via line 3. In the R and L ranges, it is supplied via the manual valve 55, so it is always supplied regardless of the throttle opening. The regulator valve 54 includes a spool 541, a torque ratio valve 80 (described later), and a line pressure control valve 9.
A booster plunger 542 controls the spool 541 by inputting an output oil pressure of 0, adjusts the gap area communicating with the second output port 544 as the spool 541 is displaced, and connects the output port 546 to the oil path 1. Outputs line pressure. From the port 544, the fluid coupling 21 passes through the oil passage 13.
Supply oil to the oil cooler and parts that require lubrication. The governor valve 24 has a well-known configuration and is attached to the input shaft 214 of the V-belt continuously variable transmission, which is the output shaft 214 of a fluid coupling, and is moved by the centrifugal force accompanying the rotation of the output shaft. By displacing the valve body 241, the opening area between the oil passage 1 to which line pressure is supplied and the oil drain port 242 is changed, and the torque ratio control valve 6 is transferred from the governor pressure output port 243 through the oil passage 2.
0, the governor pressure _Pq shown in the graph of FIG. 3, which is related to the vehicle speed, is output. The torque ratio control valve 60 has a spool 61 arranged in series with the spool 71 of the throttle valve via the spring 29, and the movement of the throttle cam 20 is transmitted from one side to the land at the left end in the figure via the spool 71. A spring load F that is a function of the throttle opening is applied by the spring 29, and the governor pressure P _q is applied from the other side to the land having a pressure receiving area A at the right end in the figure, and a load P _q due to these spring loads F and the governor pressure is applied. By adjusting the opening area of the port 62 and drain port 63 that communicate with the oil path 1 by balancing with ×A, the torque ratio control pressure related to the throttle opening and the rotation speed of the input pulley 31 is adjusted.
Pc is outputted from the output port 64 via the oil path 8 to the hydraulic cylinder 313 of the input pulley 31, and the V-belt type continuously variable transmission 30 is controlled to change speed continuously. (a) When the throttle opening θ is increased by depressing the accelerator pedal from constant speed driving where the spring load F and the governor load P _q ×A are balanced. As the spool 71 moves to the right in the figure in response to the clockwise rotation of the throttle cam and compresses the spring 29, the spring load F increases, and the state of F=P _q ×A becomes F>P _q ×A. , the spool 61 is moved to the right in the figure, the opening area of the port 62 to which line pressure is supplied is reduced, the opening area of the drain port 63 is increased, and the torque ratio control pressure Pc is lowered. By reducing the torque ratio control pressure Pc, the input pulley 31
The movable flange 312 moves to the right in FIG. 1, the effective diameter of the input pulley 31 decreases, the torque ratio T increases, and acceleration is performed. This acceleration is achieved by increasing the rotational speed of the fluid coupling output shaft 214 as the throttle opening θ increases, and the governor pressure P _q increases until a new equilibrium point of the spool 61 where F=P _q ×A is achieved. , the speed is increased in accordance with the increase in throttle opening. (b) When the throttle opening θ is reduced by reducing the amount of accelerator pedal depression from constant speed driving. Contrary to (a) above, the spool 71 moves to the left in the figure, and as a result, the spring load F applied to the spool 61 decreases, and F<P _q ×A, so the spool 61 is moved to the left in the figure and the torque is increased. specific control pressure
Pc increases pressure. Therefore, the effective diameter of the input pulley 31 increases, the torque ratio T decreases, and deceleration is performed. In this case as well, the rotational speed of the fluid coupling 214 decreases as the throttle opening θ decreases, and the governor pressure decreases so that F=P _q
The speed is decelerated to a new equilibrium point of the spool 61 which is ×A. (c) When the throttle opening θ is constant and the vehicle speed increases or decreases for some reason. The governor pressure P _q also increases or decreases as the rotational speed of the input shaft 214 changes due to fluctuations in the required torque, and the spool 61 is moved due to the imbalance between the governor load P _q ×A applied to the spool 61 and the spring load F. The spring load F increases or decreases to a new F.
An equilibrium point is obtained where = P _q . V caused by throttle cam 20 and governor valve 24
It is desirable that the belt-type continuously variable transmission be controlled so as to match the characteristic curve of fluid coupling rotational speed and throttle opening shown in FIG. 4, which allows the vehicle to be operated with the best fuel efficiency. The best fuel efficiency characteristic curve shown in Fig. 4 is 13-1.
The best fuel efficiency characteristic curve shown on the engine fuel consumption rate curve shown in the figure (connecting the minimum fuel consumption rate points on the equal horsepower line in the figure) and the equal throttle opening engine performance curve shown in Figure 13-2. This can be determined from the fluid coupling characteristic curve shown in FIG. 14, and is generally known. Such optimal fuel efficiency control is obtained from the characteristics of governor pressure and input pulley rotation speed (or fluid coupling output shaft rotation speed) shown in FIG. 3, and the characteristic curve shown in FIG. 4, as shown in FIG. It is necessary to set the governor valve so as to maintain the relationship between the throttle opening θ and the governor pressure Pq shown in FIG. Furthermore, for this purpose, it is necessary to determine the shape of the throttle cam 20 so as to obtain the relationship between the throttle opening θ and the spool 71 of the throttle valve as shown in FIG. Note that the present invention can be easily adapted to engines having different fuel efficiency characteristics by changing the shape of the throttle cam 20. The throttle valve 70 has one end connected to the throttle cam 2.
It has a spool 71 that comes into contact with the working surface of
Accordingly, when θ = θ ₁ or more, oil passage 1 is communicated with oil passage 3 and throttle pressure output oil passage 7, when θ = θ ₂ or more, oil passage 15 (described later) is evacuated, and when θ = θ ₃ or more, the pressure is discharged from oil passage 15, which will be described later. Then, the pressure in the oil passage 16, which will also be described later, is evacuated. The torque ratio valve 80 has one end attached to a movable flange 322 of the output pulley 32 of the V-belt continuously variable transmission.
It has a spool 81 which is linked via a connecting rod 34 so as to move in conjunction with the axial movement of the movable flange, and has a spring 82 on its back at the other end, and when the torque ratio T is equal to or greater than a set value _t4 . The regulator valve 54 connects the oil passage 7 and the output oil passage 9 and uses the throttle pressure supplied from the throttle valve 70 as torque ratio pressure.
Output to. The line pressure control valve 90 has a spool 91 arranged in series with the spool 81 via the spring 82, and a port 92 connected to the oil passage 6 according to the torque ratio T transmitted via the spring 82. The opening area with the drain port 93 is adjusted to output the line pressure control pressure Pa to the booster plunger of the regulator valve via the oil passage 10. This line pressure control valve 90 controls the line pressure according to the throttle opening, so it is equipped with a three-stage output oil pressure feedback mechanism that can increase or decrease the level according to the throttle opening. The oil passages 14, 15, and 16 are feedback oil passages that apply output hydraulic pressure to lands 97, 98, and 99 whose pressure receiving areas are gradually reduced through orifices 94, 95, and 96, respectively, and the action of the throttle valve 70 is As the throttle opening degree 9 increases, the pressure in the oil passage 15 and the oil passage 16 is sequentially exhausted, and the line pressure control pressure Pa increases in stages. The graph in FIG. 7 shows the characteristics of the line pressure control pressure Pa, which is the output oil pressure of the line pressure control valve 90. FIG. 8 is a graph showing the characteristics of the output line pressure of the regulator valve 54 in which the torque ratio pressure and the line pressure control pressure Pa are input to the booster plunger. The line pressure required in the hydraulic control circuit is mainly V.
The minimum necessary line pressure that does not cause belt slip in the V-belt continuously variable transmission is determined, which varies depending on the torque ratio between the input and output shafts of the belt-type continuously variable transmission and the input torque. By adjusting the line pressure as described in (1) to (6) below, the line pressure can be brought close to the minimum oil pressure required by the hydraulic control circuit, and the resulting loss of engine driving force due to the oil pump can be reduced. This makes it possible to reduce the fuel consumption rate of the engine. (1) For each throttle opening, the hydraulic pressure required to operate the engine in a preset state increases as the throttle opening (or input torque) increases, and the torque between both pulleys increases. Since it has the characteristic of increasing in response to an increase in the ratio (torque ratio between input and output shafts), the line pressure controlled by the hydraulic adjustment device can be changed to the throttle opening (or input torque) or the torque ratio between both pulleys as a parameter. By changing the line pressure in stages, the line pressure approaches the minimum oil pressure required by the hydraulic servo mechanism of the V-belt continuously variable transmission. (2) Because it is necessary to transmit a large driving force when starting, etc., the minimum hydraulic pressure required by the hydraulic servo mechanism is larger than the case described in (1).
Therefore, in such a case, a line pressure greater than the line pressure mentioned in (1) is generated. (3) The state described in (2) is detected by the torque ratio between both pulleys of the V-belt continuously variable transmission (torque ratio between the input and output shafts), and the torque ratio is set in advance. If the value becomes larger than the specified value, the state described in (2) will occur. (4) Even under the conditions described in (3), if the throttle opening is small and the engine speed is low (for example, at idle), if a large line pressure is generated as described in (2), the oil Since the pump discharge rate is small, if there is a large leakage in various parts of the oil path at high oil temperatures, problems such as a drop in line pressure, a rise in temperature due to a drop in cooler pressure, and a drop in lubrication pressure will occur, so the throttle opening should be kept at a constant value. In the following cases, the line pressure is not increased even if the torque ratio is large. (5) The L range of the manual valve shift position is the range for obtaining strong engine braking.
When the throttle is depressed and the engine is driven, the line pressure characteristics are the same as in the D range. In order to obtain strong engine braking in the L range, even when the throttle opening is low, it is necessary to supply a larger hydraulic pressure to the hydraulic servo mechanism than when driving from the engine side. The line pressure is increased even when the temperature is below a certain value. (6) It is desirable to obtain strong engine braking in the R range as well from the viewpoint of safety, and in this case, the line pressure characteristics are the same as in the L range. The minimum line pressure necessary for a change in the torque ratio T between the input and output shafts is shown by the solid line in FIG. 9 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 ratio that can be achieved by both pulleys, so as shown by the dotted line, it is approximately 20% lower than the best fuel efficiency characteristic curve shown by the solid line above. It is desirable to have the line pressure as shown by the large broken line, and it is also desirable to have a higher line pressure characteristic as shown in the dashed line even when the throttle opening θ=0 during engine braking. In this embodiment, the hydraulic adjustment device 50 adjusts the shift positions L, D, N, R, P of the manual valves and the torque ratio T between the input and output shafts of the V-belt continuously variable transmission as follows. be done.

【represent.
D position In the manual valve 55, the oil passage 4 communicates with the oil passage 1, the oil passage 9 communicates with the oil passage 3, and the oil passage 5 is discharged. (1) When the throttle opening degree θ is 0≦θ≦ _θ1 As shown in Table 2, the throttle valve 70 does not output the line pressure supplied from the oil passage 1 from either the oil passages 3 or 7. Since the torque ratio valve 80 and the line pressure control valve 90 are not supplied with oil pressure from either of the oil passages 6 and 7, they do not produce an output oil pressure, and the line pressure output from the regulator valve 54 is shown in the graph of FIG. Torque ratio or output pulley movable flange displacement L
It remains constant against changes in . (2) When the throttle opening degree θ is θ ₁ ≦θ≦θ ₂ , the throttle valve 70 connects the oil passage 1 with the oil passage 3 and the oil passage 7, and maintains the feedback oil pressure of the oil passage 15 and the oil passage 16. . As a result, the torque ratio valve 80 and the line pressure control valve 90 are supplied with throttle pressure (equivalent to the line pressure in this embodiment) and line pressure from the oil passages 6 and 7. The line pressure control valve 90 is connected to the feedback oil path 1
4, 15, and 16 act on the feedback of the line pressure control pressure, and when the torque ratio T is equal to or _higher than the set value t3, the torque ratio pressure is outputted from the oil passage 9. By inputting these line pressure control pressure and torque ratio pressure to the booster plunger 542, the line pressure output from the regulator valve 54 is adjusted as shown in FIG. (3) When the throttle opening degree θ is θ ₂ <θ≦θ ₃ , as shown in Table 2, the feedback oil passage 15 is evacuated from the state of θ ₁ ≦θ≦θ ₂ , and this causes the line pressure control pressure Pd to decrease. As the level increases, the line pressure output by the regulator valve 54 becomes as shown in FIG. (4) When the throttle opening degree θ is θ ₃ <θ≦100%, as shown in Table 2, the pressure in the feedback oil passage 16 is exhausted from the state of θ ₂ <θ≦θ ₃ , so the line pressure control pressure Pd is further increased. The line pressure output from the regulator valve 54 also increases to the line pressure control pressure.
As Pd increases, the level increases as shown in FIG. FIG. 11 is a graph showing the change in line pressure with respect to the throttle opening θ when the torque ratio T is t ₁ , t ₂ , and t ₃ . L position At the manual valve 55, the oil passage 1 is communicated with the oil passage 4 and the oil passage 6, and the oil passage 5 is depressurized. In this case, the line pressure is directly supplied to the oil passage 6 from the oil passage 1 without passing through the oil passage 3 and the throttle valve, so when the throttle opening θ is 0≦θ≦θ ₂ , the line pressure control valve is The output oil pressure has the characteristics shown in FIG. 7, and the regulator valve ₅₄ that inputs this line pressure control pressure has
The values are shown in the figure. When θ ₂ ≦ θ, it is the same as the D position, and the torque ratio T is the parameter (t ₁ , t ₂ , t ₃ )
The line pressure with respect to the throttle opening degree θ is as shown in FIG. R Position As shown in Table 1, in the manual valve 55, the oil passage 15 and the oil passage 6 communicate with the oil passage 1, and the oil passage 4 is depressurized. Since the line pressure is guided to the oil passage 6, 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 if the torque ratio T is changed at the R position, the line pressure is controlled in the same manner as at the L position. is possible. P position and N position As shown in Table 1, the oil passages 4 and 5 are depressurized in the manual valve 55, and the oil passage 6 is connected to the oil passage 3, so the line pressure that is the output of the regulator valve 54 is This is the same as position D. When the manual valve 55 is shifted to the D, N, and P shift positions during this line pressure adjustment,
The line pressure when the torque ratio T is in the range of t ₃ ≦T ≦ t ₄ is expressed as the throttle opening θ ₁ as shown in the graph of Fig. 11.
The reason why the line pressure is set to a low value below % is to prevent oil leakage from various parts of the hydraulic circuit due to high oil temperature 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. This is because when the line pressure is high, it becomes difficult to maintain the line pressure, and furthermore, the oil temperature increases due to a decrease in the amount of oil supplied to the oil cooler, which is likely to cause trouble. When the manual valve 55 is shifted to the L and R shift positions, the torque ratio T is in the range t ₃ ≦T ≦ t ₄ and the throttle opening θ is θ ₁ % or less, as shown in the graph of FIG. The line pressure was set high under these operating conditions because relatively high oil pressure is required during engine braking even when the throttle opening is low. In this way, as shown in FIG. 10, by bringing the line pressure close to the minimum necessary oil pressure shown in FIG. 9, the pump 52
Since the power loss caused by this can be reduced, fuel efficiency and fuel consumption rate can be improved. As described above, the control device for the continuously variable transmission for vehicles of the present invention controls the V-belt type continuously variable transmission using the throttle cam and the governor valve, so the structure is simple and the failure rate is low. It is possible to reduce the manufacturing cost. Furthermore, by appropriately forming the shape of the throttle cam, it is easy to achieve the best fuel efficiency control.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a continuously variable transmission for a vehicle, Fig. 2 is a hydraulic circuit diagram of a control device of the present invention, Fig. 3 is a graph showing characteristics of governor pressure, and Fig. 4 is a fluid coupling output shaft rotation. Figure 5 is a graph showing the characteristics of the throttle opening that gives the best fuel efficiency with respect to the throttle opening, Figure 6 is a graph that shows the characteristics of the governor pressure that gives the best fuel efficiency with respect to the throttle opening, and Figure 6 shows the characteristics of the governor pressure that gives the best fuel efficiency with respect to the throttle opening. A graph showing the stroke of the throttle valve spool, Fig. 7 is a graph showing the output characteristics of the line pressure control valve, Fig. 8 is a graph showing the output characteristics of the regulator valve, and Fig. 9 shows the line pressure characteristics for the best fuel efficiency. 10 is a graph showing the line pressure when the regulator valve according to the example is subjected to optimal fuel efficiency control, and FIGS. 11 and 12 are graphs in which the line pressure in FIG. 10 is displayed in relation to the throttle opening. Figure 13-1 is a graph showing an engine performance curve expressed as an equal fuel consumption rate curve.
FIG. 2 is a graph showing an engine characteristic curve expressed in terms of throttle opening, and FIG. 14 is a graph showing a fluid coupling characteristic curve. In the figure, 21... Fluid coupling, 30... V-belt type continuously variable transmission, 40... Planetary gear transmission, 31
...Input side pulley, 32...Output side pulley, 20...Throttle cam, 29...Spring, 24...Governor valve, 6
0...Torque ratio control valve.

Claims (1)

[Claims] 1. A continuously variable transmission for a vehicle, which includes an input pulley and an output pulley that are attached to the input shaft and the output shaft, respectively, and whose effective diameters are variable by hydraulic pressure, and a V-belt that transmits power between these pulleys. The machine control system includes a hydraulic source, a regulator valve that regulates the hydraulic pressure from the hydraulic source to line pressure, a governor valve that outputs governor pressure that corresponds to the pulley rotation speed, and a throttle cam displacement that corresponds to the throttle opening. a throttle valve having a spring that is pressed by a spring; and a torque ratio control valve that outputs hydraulic pressure for operating the input-side pulley or the output-side pulley, and the throttle valve applies hydraulic pressure corresponding to the throttle opening to the regulator. The regulator valve inputs a hydraulic pressure corresponding to the throttle opening to set the line pressure to a hydraulic pressure corresponding to the throttle opening, and the torque ratio control valve controls the spring load on one side. and a spool that receives governor pressure so as to bias the load of the spring on the other side, and the line pressure corresponding to the throttle opening input to the torque ratio control valve is controlled by the spool. A control device for a continuously variable transmission for a vehicle, characterized in that the control device controls either the input pulley or the output pulley. 2. The control device for a continuously variable transmission for a vehicle as set forth in claim 1, wherein the operating surface of the throttle cam is shaped to be able to apply a pressing force to the spring that provides the best fuel efficiency.