JP2001012590A - Control device for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an automatic transmission capable of feeding a hydraulic pressure such that a primary pulley is not shifted up to the primary pulley side in an under drive condition so as to maintain an appropriate under drive condition. SOLUTION: A check valve 93 connected to a hydraulic pressure source 73 is connected to a hydraulic actuator 33 of a primary pulley, and feedback means is provided between an output port B of the check valve and operating sources 93a and 93b of the check valve. The operating sources are controlled so that the hydraulic pressure of the hydraulic actuator of the primary pulley becomes a first specified value Pps (BAL) or below and a second specified value Pps (LOW) or above in order to prevent the hydraulic pressure fed to the primary pulley from rising excessively.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a control device for a continuously variable transmission mounted on an automobile.

2. Description of the Related Art Conventionally, as a continuously variable transmission for a vehicle, there has been known a continuously variable transmission including a primary pulley, a secondary pulley, and a belt wound between the pulleys.
The gear shifting operation is performed by changing the pulley ratio by controlling the hydraulic pressure supplied to the sheaves of the primary pulley and the secondary pulley. However, in a sudden deceleration operation of the vehicle, the hydraulic pressure in the sheave of the primary pulley is rapidly discharged. It is necessary to hold the transmission on the underdrive side.

At this time, the hydraulic pressure from the secondary regulator valve is supplied to the primary pulley through the check valve so that the pressure oil in the sheave of the primary pulley is not excessively released and does not hinder the subsequent upshift operation. A method has been proposed in Japanese Patent Publication No. 3-1542.

[0003]

However, in such a method, if the hydraulic pressure supplied to the primary pulley is too high, the primary pulley may shift up to the overdrive side, and some improvement has been desired.

In view of the above circumstances, the present invention can supply hydraulic pressure to the primary pulley so that the primary pulley does not upshift in an underdrive state, and can maintain an appropriate underdrive state. It is an object of the present invention to provide a control device for a continuously variable transmission.

[0005]

According to a first aspect of the present invention, there is provided a primary pulley (26), a secondary pulley (31) and a belt (32) wound between the primary pulley and the secondary pulley. The primary hydraulic pressure and the secondary hydraulic pressure are appropriately supplied to the hydraulic actuators (33, 35), and the primary hydraulic pressure supplied to the hydraulic actuator of the primary pulley is supplied / discharged through a supply / discharge valve means (92), so that the pulleys between In the control device for a continuously variable transmission (1) which changes the pulley ratio by changing the pulley ratio, a check valve (93) connected to a hydraulic source (73) is connected to a hydraulic actuator (33) of the primary pulley (26). From the hydraulic source only in the direction of the hydraulic actuator of the primary pulley. As well as connected so as to be supplied to the output port of the check valve (B), an operational source of the check valve the oil pressure of the output port (93a, 93
b) providing feedback means for feeding back,
With the operation source, the hydraulic pressure from the hydraulic pressure source is adjusted so that the hydraulic pressure of the hydraulic actuator of the primary pulley is equal to or less than a first predetermined value (Pps (BAL)) and a second predetermined value (Pps (LOL)).
W)) The supply control is performed as described above.

According to a second aspect of the present invention, in the control device for a continuously variable transmission according to the first aspect, the secondary pulley (3
The first regulator valve (7) that supplies the line pressure to the hydraulic actuator (35) of 1) as the secondary hydraulic pressure
2) and a second regulator valve (73) for adjusting a hydraulic pressure lower than the line pressure is provided.
It is characterized by being a regulator valve.

According to a third aspect of the present invention, in the control device for a continuously variable transmission according to the first aspect, the check valve (93) is provided.
Has a valve (93a) that can freely close and release between the input port (A) and the output port (B), and the actuation source constantly biases the valve toward the input port. (93
b), wherein the operating source is driven by a pressing force of the urging means and a pressing force of a hydraulic pressure of the output port (B) supplied from the feedback means.

According to a fourth aspect of the present invention, in the control device for a continuously variable transmission according to the first aspect, the first predetermined value is set when the pulley ratio of the pulley is in an underdrive state. Is a hydraulic pressure (Pps (BAL)) that balances with the secondary pulley (31) in the underdrive state.

According to a fifth aspect of the present invention, in the control device for a continuously variable transmission according to the first aspect, the second predetermined value is such that the primary pulley is connected to the belt when the pulley ratio of the pulley is in an underdrive state. And a minimum hydraulic pressure (Pps (LOW)) that causes a slip between the two.

According to a sixth aspect of the present invention, in the control device for a continuously variable transmission according to the first aspect, a first regulator valve (72) for supplying a line pressure as a secondary hydraulic pressure to a hydraulic actuator of the secondary pulley and the line. A second regulator valve for supplying a constant oil pressure lower than the pressure is provided, and the oil pressure source is the second regulator valve.

According to a seventh aspect of the present invention, in the control device for a continuously variable transmission according to the second aspect, the second regulator valve generates a hydraulic pressure corresponding to an input torque to the continuously variable transmission. Is configured as

[0012]

According to the first aspect of the present invention, the output port (B) of the check valve is provided with feedback means for feeding back the hydraulic pressure of the output port to the operation sources (93a, 93b) of the check valve. Supply control such that the hydraulic pressure of the hydraulic actuator of the primary pulley is equal to or less than a first predetermined value (Pps (BAL)) and equal to or more than a second predetermined value (Pps (LOW)). Therefore, it is possible to prevent the hydraulic pressure supplied to the primary pulley from becoming too high. Thus, in the underdrive state after the rapid deceleration, the hydraulic pressure on the primary pulley side can be prevented from being released, and the hydraulic pressure can be supplied to such an extent that the primary pulley does not upshift, and the proper underdrive state can be maintained. Thus, it is possible to provide a highly reliable control device for a continuously variable transmission.

According to the second aspect of the present invention, an existing regulator valve (73) can be used as the second regulator valve, and there is no need to reduce a high line pressure and supply it to the check valve (93). Thus, the apparatus can be simplified.

According to the third aspect of the present invention, the urging means (93)
The operation source can be configured with a simple configuration such as b) and feedback means, thereby preventing the device from becoming complicated.

According to the present invention, the hydraulic pressure supplied to the hydraulic actuator (33) of the primary pulley (26) balances the primary pulley (26) with the secondary pulley (31) in the underdrive state. Since the hydraulic pressure is lower than the hydraulic pressure (Pps (BAL)), it is convenient to prevent the primary pulley from being inadvertently upshifted from the underdrive state.

According to the fifth aspect of the present invention, when the hydraulic pressure supplied to the hydraulic actuator (33) of the primary pulley (26) is such that the primary pulley is in contact with the belt when the pulley ratio of the pulley is in an underdrive state. Is supplied with a minimum hydraulic pressure (Pps (LOW)) that causes slippage, so that the primary pulley is prevented from slipping out due to excessive hydraulic pressure.

According to the sixth aspect of the present invention, when the hydraulic pressure source is constituted by the second regulator valve for supplying a constant hydraulic pressure lower than the line pressure, a constant hydraulic pressure is supplied to the check valve side irrespective of the engine input torque. You can do it. Thus, the hydraulic pressure (Pps) supplied to the hydraulic actuator of the primary pulley via the check valve shown in FIG. 7 can be finely adjusted by adjusting the hydraulic pressure supplied from the second regulator valve. Variations in the performance of physical components such as the feedback spring (93b) can be guaranteed.

According to the seventh aspect of the present invention, the existing secondary regulator valve (73) can be used as the second regulator valve, so that no new parts are required and the configuration can be simplified.

The numbers and the like in parentheses are for convenience of indicating corresponding elements in the drawings, and therefore, the present description is not limited to the description on the drawings.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

A continuously variable transmission 1 shown in FIG. 1 includes a CVT (belt type continuously variable transmission) 2, a forward / reverse switching device 3, a torque converter 6 including a lock-up clutch 5, a counter shaft 7, and a differential device 9. These devices and members are housed in a split case (not shown).

The torque converter 6 includes an engine output shaft 1
0, a pump impeller 11 connected via a front cover 17, a turbine runner 13 connected to an input shaft 12, and a stator 16 supported via a one-way clutch 15. The lock-up clutch 5 is interposed between the input shaft 12 and the front cover 17. In the drawing, reference numeral 20 denotes a damper spring interposed between the lock-up clutch plate and the input shaft 12, and reference numeral 21 denotes a pump impeller 11
Is an oil pump that is connected to and driven.

The CVT 2 is fixed to a primary pulley 26 composed of a fixed sheave 23 fixed to a primary shaft 22, a movable sheave 25 supported on the primary shaft 22 so as to freely slide only in the axial direction, and a secondary shaft 27. Secondary pulley 3 including a fixed sheave 29 and a movable sheave 30 supported only on the secondary shaft 27 so as to freely slide only in the axial direction.
1 and a metal belt 32 wound around the primary pulley 26 and the secondary pulley 31.

Further, a hydraulic actuator 33 composed of a double piston is provided on the back of the primary movable sheave 25.
Are arranged, and a hydraulic actuator 35 composed of a single piston is arranged on the back of the secondary movable sheave 30. The primary hydraulic actuator 33 includes a cylinder member 36 and a reaction force support member 37 fixed to the primary shaft 22 and a movable sheave 2.
5, a first hydraulic chamber 41 is formed on the back surface of the cylindrical member 39, the reaction force support member 37, and the movable sheave 25, and the cylinder member 39 The second hydraulic chamber 42 is constituted by the piston 36 and the piston member 40. And, these first hydraulic chambers 4
Since the first and second hydraulic chambers 42 are communicated with each other through the communication hole 37a, the axial force is almost twice as large as the axial force generated in the secondary hydraulic actuator 35 by the same hydraulic pressure as a whole. Occurs. On the other hand, the secondary-side hydraulic actuator 35 has a reaction force support member 43 fixed to the secondary shaft 27 and a tubular member 45 fixed to the back surface of the movable sheave 30. One hydraulic chamber 46 is formed by the
And the movable sheave 30 and the reaction force support member 4
The spring 47 for preloading is contracted in the question of 3.

The forward / reverse switching device 3 has a double pinion planetary gear 50, a reverse brake B1 and a forward clutch Cl. In the above-described double pinion planetary gear 50, the sun gear S is connected to the input shaft 12, the carrier CR that supports the first pinion P1 and the second pinion P2 is connected to the primary fixed sheave 23, and The ring gear R is connected to the reverse brake Bl, and the forward clutch Cl is interposed between the carrier CR and the ring gear R.

A large gear 51 and a small gear 52 are fixed to the counter shaft 7. The large gear 51 meshes with a gear 53 fixed to the secondary shaft 27, and the small gear 52 is a gear 55 of the differential device 9. Is engaged. In the differential device 9, the differential gear 5 supported by the differential case 66 having the gear 55
The rotation of 6 is transmitted to left and right axles 60 and 61 via left and right side gears 57 and 59.

A number of uneven portions 23a are formed at regular intervals on the outer peripheral portion of the primary fixed sheave 23 by gear cutting, and are fixed to a case (not shown) so as to face these uneven portions 23a. An electromagnetic pickup 62 is disposed. Similarly, a large number of concave and convex portions 29a are formed at regular intervals on the outer peripheral portion of the secondary side fixed sheave 29 by gear cutting, and the electromagnetic pickup 63 is fixed to the case so as to face these concave and convex portions 29a. Have been. These electromagnetic pickups 62 and 63 have their detection surfaces arranged near the above-mentioned uneven portions 23a and 29a, respectively, and have primary (input) rotational speed sensors and secondary (output) rotational speeds for detecting the uneven portions 23a and 29a, respectively. This constitutes a sensor (vehicle speed sensor). An electromagnetic pickup 65 is arranged near the front cover 17, and the electromagnetic pickup 65 constitutes an engine speed sensor. Then, the input torque is obtained by calculating the engine torque based on the throttle opening and the engine speed by using the map, further calculating the speed ratio from the input / output speed of the torque converter 6, and obtaining the torque ratio by using the speed ratio on the map. It is determined by multiplying the engine torque by this torque ratio.

Next, an outline of a hydraulic circuit of the continuously variable transmission 1 of the present invention will be described with reference to FIG. FIG.
, 21 is the above-described oil pump, 72 is a primary regulator valve, 73 is a secondary regulator valve, 76 is a solenoid modulator valve, SL
T is a line pressure control linear solenoid valve, and SLU is a secondary pressure control linear solenoid valve. 7
Reference numeral 7 denotes a manual valve, and the modulation pressure (oil pressure at the port PL) regulated by the clutch modulator valve 79 is switched to a plurality of ports on the left and right in the figure by manual operation. 80 is a Cl control valve, 81 is a relay valve, 82 is a B1 control valve also serving as a reverse inhibit valve, and Sl is a solenoid valve for switching a relay valve. Also,
Cl is a hydraulic servo for the aforementioned forward clutch Cl,
Bl is the hydraulic servo for the reverse brake Bl described above, 9
Reference numerals 0 and 91 denote accumulators for Bl and Cl, respectively.

Reference numeral 92 denotes a ratio control valve, reference numerals 33 and 35 denote the above-mentioned primary hydraulic actuator and secondary hydraulic actuator, and reference numeral 93 denotes a check valve. The hydraulic pressure is applied between the secondary regulator valve 73 and the primary hydraulic actuator 33 through an orifice 97. The secondary regulator valve 73 is connected so as to be able to supply only to the hydraulic actuator 33.
As shown in FIG. 7, the check valve 93 is provided with a valve 93a so as to be able to open and close between the input port A and the output port B, and a feedback spring 93b connects the valve 93a to the port A. It is provided in such a manner that it is always biased to the side. The port B of the check valve 93 is connected to the hydraulic actuator 33,
3a is connected to the port C on the side of the feedback spring 93b.

Reference numeral 94 in FIG. 2 denotes a primary sheave control valve. Reference numeral 95 denotes a lock-up control valve, reference numeral 96 denotes a lock-up relay valve, and reference numeral S3 denotes a lock-up switching solenoid valve also serving as reverse inhibit means. In the figure, EX is a drain port, and 100 is a cooler.

Next, the operation of the continuously variable transmission 1 and the hydraulic circuit having the above-described configuration will be described. When the oil pump 21 is started based on the engine rotation, a predetermined oil pressure is generated. This oil pressure is based on a linear solenoid valve SLT controlled by a signal from a control unit calculated based on a pulley ratio and an input torque.
Thus, the secondary pressure Ps is adjusted by the secondary regulator valve 73.

In the D range of the manual valve 77, the hydraulic pressure from the port PL changes from the port D on the right in FIG.
1 is supplied to the hydraulic clutch Cl for the forward clutch via the control valve 80 and the relay valve 81, and the forward clutch Cl is connected. In this state, the rotation of the engine output shaft 10 is transmitted through the primary pulley 2 via the planetary gear 50 which is directly connected by the torque converter 6, the input shaft 12, and the forward clutch Cl.
6 is transmitted to the secondary shaft 27 via the CVT 2 which is appropriately shifted, and transmitted to the left and right axles 60 and 61 via the counter shaft 7 and the differential device 9.

When the manual valve 77 is operated in the R (reverse) range, the hydraulic pressure from the port PL is reduced as shown in FIG.
It is supplied from the left port R to the brake hydraulic servo Bl via the B1 control valve 82 and the relay valve 81. In this state, the ring gear R of the planetary gear 50 is locked, and the rotation of the sun gear S from the input shaft 12 is taken out as reverse rotation by the carrier CR, and this reverse rotation is transmitted to the primary pulley 26.

The above-mentioned CVT 2 is a secondary pulley 31
The line pressure PL from the primary regulator valve 72 is supplied to the hydraulic actuator 35 as a secondary hydraulic pressure Psec, and exerts a belt clamping force according to the input torque and the gear ratio. On the other hand, based on the shift signal from the control unit, the ratio control linear solenoid valve S
LR is controlled, the ratio control valve 92 is controlled by the (signal pressure) from the ratio control linear solenoid valve SLR, and the hydraulic pressure from its output port is applied to the hydraulic actuator 33 composed of the double piston of the primary pulley 26 by the primary hydraulic pressure. The speed ratio of the CVT 2 is appropriately controlled.

Then, the torque of the engine output shaft 10 is
The torque is transmitted to the input shaft 12 via the torque converter 6, and particularly at the time of starting, the speed is changed by the torque converter 6 so that the torque ratio is increased and transmitted to the input shaft 12, and the vehicle starts smoothly. Also, the torque converter 6
It has a lock-up clutch 5, and when the vehicle is running at high speed and stable, the lock-up clutch 5 is engaged,
The engine output shaft 10 and the input shaft 12 are directly connected to reduce the power loss due to the oil flow of the torque converter 6.

Next, control of the movable sheave 25 of the primary pulley 26 to the hydraulic actuator 33 during rapid deceleration and subsequent stop or low speed will be described with reference to FIG.

Normally, when the vehicle is suddenly decelerated, the hydraulic pressure of the hydraulic actuator 33 of the movable sheave 25 of the primary pulley 26 is quickly drained by the ratio control valve 92, and the CVT 2 is driven in underdrive (U
/ D) state. At this time, for example, when the vehicle is stopped after a sudden deceleration, the primary hydraulic pressure Pps to be held by the hydraulic actuator 33 of the movable sheave 25 of the primary pulley 26 and the hydraulic actuator 35 of the movable sheave 30 of the secondary pulley 27 are supplied. The relationship between the secondary hydraulic pressure Psec to be performed and the engine input torque is as shown in FIG. That is, in order to transmit power smoothly without the belt 32 slipping, both the primary and secondary hydraulic pressures Pps and Psec need to be equal to or more than a predetermined value, but the primary hydraulic pressure Pps does not enter an unnecessary upshift operation. In addition, the underdrive state is maintained,
That is, it is necessary to maintain the pressure at or below the balance primary hydraulic pressure Pps (BAL) for balancing in the underdrive state.

Therefore, when hydraulic pressure is drained from the hydraulic actuator 33 of the primary pulley 26 through the ratio control valve 92, the primary pulley 2
When the hydraulic pressure between the hydraulic actuator 33 and the ratio control valve 92 decreases to a predetermined value or less,
Secondary regulator valve 73 to orifice 97
From the check valve 93 to the primary pulley 2
The hydraulic pressure is supplied to the hydraulic actuator 33 of No. 6 so that the primary hydraulic pressure Pps becomes the balance primary hydraulic pressure Pps (BA
L) and is maintained so as to be equal to or higher than the so-called non-slip primary hydraulic pressure Pps (LOW) at which the belt 32 does not slip.

At this time, as shown in FIG. 4, the secondary pressure Psec supplied to the check valve 93 increases in proportion to the engine input torque Nin, and in a region where the engine input torque Nin is small, the secondary pressure Psec increases. Is U
Since the secondary pressure Psec is directly supplied to the movable sheave 33 of the primary pulley 26 since the secondary pressure Psec is higher than the balance primary oil pressure Pps (BAL) of the primary pulley 26 in the / D state, the hydraulic actuator 33
The internal pressure becomes equal to or higher than the balance primary oil pressure Pps (BAL), which may cause an upshift.

Therefore, the check valve 93 feeds back the oil pressure from the output port B to the feedback port C, and controls the secondary pressure Psec of the input port A so as not to be supplied to the primary pulley 26 as it is.

That is, as shown in FIG. 7, the effective pressure receiving area of the valve 93a at the input port A of the check valve 93 on the side of the secondary regulator valve 73 is obtained by subtracting the area of the donut-shaped seal portion 93c from the effective pressure receiving area. ₂ ,
When the diameter is d ₂ , the pressure receiving area of the valve 93 a on the feedback port C side is A ₁ , the diameter is d _1, and the biasing force of the feedback spring 93 b is Fsp, the check valve 93 is closed. Of the primary pulley 26 to the valve 93a by the primary hydraulic pressure Pps and the urging force Fsp of the feedback spring 93b.
And the pressing force of the secondary pressure Psec against the valve 93a is balanced, so that the primary hydraulic pressure Pps is set as shown in FIG.
It is calculated as shown in The primary hydraulic pressure Pps determined in this way is the balance primary hydraulic pressure Pps (BA
L) The primary hydraulic pressure Pps (LO
W) The biasing force Fsp of the spring of the feedback spring 93b and the diameters d ₁ and d ₂ of the valve 93a are set so as to satisfy the condition (1) in the drawing. In this case, since the valve 93a is closed and the secondary pressure Psec does not act on the seal portion 93c, the hydraulic pressure of the seal portion 93c of the valve 93a is 0 in the secondary pressure Psec.
Is calculated as When the valve 93a of the check valve 93 is opened, the secondary pressure P of the seal 93c on the port A side of the valve 93a is increased.
Assuming that sec changes linearly, the pressing force on the valve 93a by the primary oil pressure Pps, the urging force Fsp of the feedback spring 93b, and the pressing force on the valve 93a including the seal portion 93c of the secondary pressure Psec are balanced. Therefore, the primary oil pressure Pps is calculated as shown in FIG. The primary oil pressure Pps obtained in this way is equal to or less than the balance primary oil pressure Pps (BAL) and equal to or more than "0", that is, (2) in the figure.
In order to satisfy the equation, the feedback spring 93b
And the diameters d ₁ and d ₂ of the valve 93a are set.

That is, to satisfy the equations (1) and (2) in FIG. 7, the spring urging force Fsp of the feedback spring 93b and the pressure receiving area of the valve 93a, and hence the diameter d ₁ ,
By setting d ₂ , the check valve 93 is set in FIG.
As shown in FIG. 7, the opening / closing pressure Poc is set. Then, the secondary pressure Psec is increased by the check valve 93.
It is supplied to the hydraulic actuator 33 of the primary pulley 26 in a form adjusted to a pressure equal to or lower than the balance primary oil pressure Pps (BAL) and equal to or higher than the primary oil pressure Pps (LOW) which does not cause the primary pulley 26 to slip. As a result, even when the vehicle is suddenly decelerated, the hydraulic pressure of the primary pulley 26 is not only prevented from being excessively drained but also maintained at an appropriate pressure that does not cause an inadvertent upshift.

In the above embodiment, the check valve 9 is used.
Although the case has been described where the hydraulic pressure supplied to 3 is the secondary pressure Psec, the hydraulic pressure supplied to the check valve 93 is not limited to the secondary pressure Psec, and may be a hydraulic pressure adjusted by a suitable pressure adjusting means such as a modulator valve. In this case, the hydraulic pressure supplied from the pressure adjusting means does not need to be a hydraulic pressure proportional to the input torque Tin, as shown in FIG.
As shown in FIG. 5, the hydraulic pressure Pm may be adjusted to a constant pressure by an appropriate modulator valve.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a belt-type continuously variable transmission.

FIG. 2 is a diagram showing a hydraulic circuit to which the present invention is applied.

FIG. 3 is a hydraulic circuit diagram showing a main part of FIG. 2;

FIG. 4 is a diagram showing a relationship between an engine input torque and various pressures.

FIG. 5 is a diagram showing a relationship between an engine input torque and various pressures.

FIG. 6 is a diagram showing a relationship between an engine input torque and a primary hydraulic pressure and a secondary hydraulic pressure.

FIG. 7 is a diagram showing a calculation of a pressure balance acting when the check valve is opened and closed;

[Explanation of symbols]

1 Continuously variable transmission 26 Primary pulley 31 Secondary pulley 32 Belt 33, 35 Hydraulic actuator 72 First regulator valve (primary regulator valve) 73 Second regulator valve Hydraulic source (secondary regulator valve) 92 Supply / discharge valve means (ratio control valve) 93 Check valve 93a Actuation source (valve) 93b Actuation source, biasing means (feedback spring) Pps (BAL) ... First predetermined value (balance primary hydraulic pressure) Pps (LOW)... Second predetermined value (non-slip primary hydraulic pressure)

Continuing on the front page (72) Inventor Norio Imai 10 Takane, Fujii-machi, Anjo, Aichi Prefecture Inside Aisin AW Co., Ltd. (72) Inventor Akihito Iwata 10 Takane, Fujii-cho, Anjo, Aichi Prefecture Within the Company, Inc. (72) Inventor Junichi Tokunaga 10th Takane, Fujii-machi, Anjo-shi, Aichi F-term within the Company, Aisin AW Co., Ltd. (Reference) 3J052 AA04 CA32 FA01 FB02 FB05 FB27 FB34 GC13 GC23 GC72 HA11 KA01 LA01

Claims (7)

[Claims] 1. A primary pulley, a secondary pulley, and a belt wound between the pulleys, and a primary hydraulic pressure and a secondary hydraulic pressure are appropriately supplied to hydraulic actuators of the primary pulley and the secondary pulley, and a hydraulic pressure of the primary pulley is provided. A control device for a continuously variable transmission that changes the pulley ratio between the pulleys by supplying and discharging primary hydraulic pressure to be supplied to an actuator through a supply and discharge valve means. A check valve connected to a check valve is connected so that hydraulic pressure can be supplied only from the hydraulic pressure source toward the hydraulic actuator of the primary pulley, and an output port of the check valve is connected to an output port of the check valve. The operation source Feedback control means for controlling the supply of the hydraulic pressure from the hydraulic pressure source so that the hydraulic pressure of the hydraulic actuator of the primary pulley is equal to or less than a first predetermined value and equal to or more than a second predetermined value. A control device for a continuously variable transmission, wherein: 2. The control device for a continuously variable transmission according to claim 1, wherein a first regulator valve for supplying a line pressure as a secondary hydraulic pressure to a hydraulic actuator of the secondary pulley and a hydraulic pressure lower than the line pressure are adjusted. A second regulator valve is provided, and the hydraulic pressure source is the second regulator valve. 3. The control device for a continuously variable transmission according to claim 1, wherein the check valve has a valve that can be closed and released between an input port and an output port, and the operation source is the valve. The operating source is driven by a pressing force of the urging unit and a pressing force of a hydraulic pressure of the output port supplied from the feedback unit. It is characterized by the following. 4. The control device for a continuously variable transmission according to claim 1, wherein the first predetermined value is such that when the pulley ratio of the pulley is in an underdrive state, the primary pulley is connected to the secondary pulley and the underdrive. It is characterized by hydraulic pressure balanced in the driving state. 5. The control device for a continuously variable transmission according to claim 1, wherein the second predetermined value is such that when the pulley ratio of the pulley is in an underdrive state, the primary pulley slides between the primary pulley and the belt. The minimum hydraulic pressure that causes 6. The control device for a continuously variable transmission according to claim 1, wherein a first regulator valve that supplies a line pressure as a secondary hydraulic pressure to a hydraulic actuator of the secondary pulley, and a constant hydraulic pressure lower than the line pressure. A second regulator valve for regulating pressure is provided, and the hydraulic pressure source is the second regulator valve. 7. The control device for a continuously variable transmission according to claim 2, wherein the second regulator valve generates a hydraulic pressure corresponding to an input torque to the continuously variable transmission.