JP2792370B2 - Hydraulic control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device, and more particularly, to a hydraulic pressure detecting structure for hydraulic control.

[0002]

2. Description of the Related Art As a structure used in a so-called stepless speed change mechanism, a belt is stretched between a pair of pulleys, and a groove width of the pulley on which the belt is hung is changed so that a drive side is connected to the pulley. There is a structure that changes the speed ratio obtained between the driven side and the driven side.

One of the mechanisms for changing the groove width of the pulley includes a movable conical plate which is opposed to one fixed conical plate constituting the pulley by using a hydraulic mechanism. There is a structure to displace in the direction.

[0004] An example of the above-mentioned hydraulic mechanism is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-19755. In this structure, the oil from the oil pump set to a predetermined pressure by the pressure regulating valve is connected to the hydraulic chamber side of the movable conical plate in the driven pulley, and the oil path is extended from the pressure regulating valve to be connected. The pressure is set so as to obtain a transmission ratio at which the engine-side output torque can be transmitted through the flow control valve, and then the pressure is guided to the hydraulic chamber in the movable conical plate of the drive pulley.

[0005]

By the way, in the above-mentioned transmission mechanism, when the groove width for obtaining the required speed ratio is set, the pressure of the hydraulic chamber on the pulley side is adjusted by the pressure adjusting valve. A compressed line pressure is provided, which must be adjusted to maintain a frictional engagement between the belt and the conical plate.

That is, when the engine side torque is large, in other words, when the engine is operated with a large throttle opening, the gear ratio is also increased. The width must be reduced so that the pressing force against the belt can be increased.

On the other hand, when the engine is driven at a constant speed, the above-mentioned engine side torque becomes small, so that an economical operating state can be set in consideration of fuel efficiency. Pressing force occurs,
Contrary to this, it is necessary to adjust the groove width on the pulley side so that the belt does not slip.

Therefore, during the above-mentioned constant speed operation, the adjustment of the groove width is more important than when the gear ratio is increased,
For this reason, it is necessary to detect the line pressure corresponding to the operating pressure in the hydraulic control unit for adjusting the groove width on the pulley side.

For this reason, conventionally, the hydraulic pressure in the hydraulic chamber on the driven pulley side is detected and tracked by a hydraulic pressure sensor disposed at that position, and the groove width of the pulley on the drive side is determined. Is output as pressure data for feedback control when the conical plate is displaced in conjunction with the change in the pressure.

In addition to the above-described structure, there has been proposed a structure in which a hydraulic pressure sensor is provided in a hydraulic circuit for applying operating pressure to a forward clutch and a reverse brake (for example, Japanese Patent Application No. 3-39466).

A brief description of the latter structure will be given. An operation mode selection manual in which an oil passage for a forward clutch and a reverse brake in a forward / reverse switching mechanism is connected to switch the direction of applying hydraulic pressure to each part. The output circuit of the clutch pressure control valve is connected to the valve. In this clutch pressure control valve, the output oil pressure is controlled by the duty control pressure of the solenoid valve with respect to the operating pressure set by the clutch pressure modulating valve. The duty control pressure circuit of the solenoid valve is connected to a clutch pressure control valve via a clutch control pressure switching valve. Further, the clutch control pressure switching valve switches the circuit according to the differential pressure between the pressure set by the clutch pressure modulating valve and the output pressure by the clutch pressure control valve. In other words, until the forward clutch and the reverse brake are switched from the disengaged state to the engaged state, the solenoid valve is controlled to prevent the pressure from the clutch pressure modulating valve for the clutch from rising sharply. The clutch engagement shock (N → D, N → R shock) is reduced.

In this hydraulic circuit, a hydraulic pressure sensor is arranged in an oil passage connecting the above-described clutch pressure control valve and the manual valve for operating mode selection.
For this reason, in the D range operation state where the clutch is completely engaged, a clutch pressure modulating valve for introducing the line pressure when the line pressure is lower than the maximum clutch pressure, and a communication state with the valve are set. The line pressure is detected by a hydraulic pressure sensor via a clutch pressure control valve which is adapted to displace the spool to a position where the spool is displaced. The detected line pressure is taken into the control section for feedback control for setting the groove width of the driven pulley to which the line pressure is applied.

However, in such a pressure detecting structure for setting the groove width, for example, in the case of the former structure, the hydraulic sensor attached to the hydraulic circuit is relatively expensive.
Using such an expensive device only for line pressure detection is costly and wasteful.

Further, in the latter structure, although it is possible to detect the line pressure at the time of constant speed operation, the position of the hydraulic sensor for that purpose is determined by the position of the clutch for setting the clutch operating pressure. Since it is located downstream of the pressure modulating valve, only the line pressure corresponding to or less than the clutch operating pressure set by the clutch pressure modulating valve can be detected. That is, the line pressure set higher than the operating pressure set by the clutch pressure modulating valve cannot be detected because the upper limit of the pressure is set.

An object of the present invention is to use a hydraulic sensor only for detecting a line pressure for setting a groove width of a pulley in view of the above-mentioned conventional hydraulic mechanism, particularly, a problem in a hydraulic pressure detecting structure. In addition to reducing the cost for hydraulic pressure detection by eliminating the problem, it is possible to detect the line pressure over the entire range, so that feedback control on the servo pressure of the driven pulley can be performed under any conditions during traveling. It is another object of the present invention to obtain a hydraulic control device having a structure that can be performed in any of the above.

[0016]

In order to achieve this object, the present invention has a forward / reverse switching device comprising a friction element, and changes the pulley width of a driving pulley and a driven pulley by hydraulic pressure. In a hydraulic control device of a continuously variable transmission that performs a continuously variable transmission by changing a winding diameter of an endless belt that is stretched between both pulleys, a regulator valve that regulates a discharge pressure from a hydraulic source, A clutch pressure control valve for adjusting the oil pressure supplied to the friction element, oil pressure detection means for detecting the oil pressure supplied to the friction element and the oil pressure adjusted by the regulator valve, and the regulator valve And a switching valve for switching and connecting to the first oil passage connected to the first oil passage or the second oil passage connected to the friction element.

According to a second aspect of the present invention, there is provided an endless belt having a forward / reverse switching device comprising a friction element, wherein a pulley width of a driving pulley and a driven pulley is changed by hydraulic pressure and is stretched between the two pulleys. In a hydraulic control device for a continuously variable transmission that performs a continuously variable transmission by changing a winding diameter, a regulator valve that regulates a discharge pressure from a hydraulic source, a first solenoid valve that controls the regulator valve, A clutch pressure control valve for adjusting the oil pressure supplied to the element, a second solenoid valve for controlling the clutch pressure control valve, and an oil pressure for detecting the oil pressure supplied to the friction element and the oil pressure adjusted by the regulator valve Disconnecting means for switching and detecting the oil pressure detecting means to a first oil path connected to the regulator valve or a second oil path connected to the friction element; When the hydraulic pressure detecting means is connected to the first oil passage by the valve and the switching valve, the first solenoid valve is feedback-controlled in accordance with a detection value of the hydraulic pressure detecting means, and the hydraulic pressure detection is performed by the switching valve. And control means for performing feedback control of the second solenoid valve in accordance with a value detected by the hydraulic pressure detection means when the means is connected to the second oil passage.

[0018]

According to the present invention, when the clutch is engaged by the duty control of the solenoid valve via the clutch pressure control valve, the port for introducing the line pressure at the switching valve and the hydraulic pressure detection oil passage are connected. The line pressure can be detected by the oil pressure sensor in the oil pressure detection oil passage by setting the communication position.

Further, according to the present invention, when the position of the operation mode select manual valve is at "N" or "P" with respect to the above-mentioned hydraulic pressure detection oil passage, furthermore, from this position "D" Is switched to, and while the forward clutch or the reverse brake is engaged, the switching valve is set in a state of communicating the output pressure of the clutch pressure control valve with the hydraulic pressure detection oil passage,
By detecting the output pressure of the clutch pressure control valve, feedback control for duty control of the clutch operating pressure can be performed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a hydraulic circuit diagram for explaining the configuration of a hydraulic control mechanism according to an embodiment of the present invention.

Before describing this circuit, a continuously variable transmission using this circuit will be described with reference to FIG.

That is, the continuously variable transmission used in this embodiment is attached to a fluid coupling 2 connected to the output shaft 1A of the engine 1.

And, this fluid coupling 2
It has a lock-up mechanism, and controls the oil pressure in the lock-up hydraulic chamber 2A to bring the pump impeller -2B on the input side and the turbine runner -2C on the output side into frictional engagement or apart from each other, thereby making the frictional engagement The relationship is released.

The above-mentioned fluid coupling 2 has an output shaft 2D provided on the output side thereof so as to be integrally rotatable.
The output shaft 2D is connected to the forward / reverse switching mechanism 3.

The forward / reverse switching mechanism 3 includes a planetary gear mechanism 4 having a well-known structure, a forward clutch 6 and a reverse brake 5, and the planetary gear is controlled by hydraulic control of the forward clutch 6 or the reverse brake 5. The rotation direction of the rotation shaft 4A connected to the output side of the mechanism 4 is switched.

On the other hand, a drive pulley 7 which is one of the main parts of the continuously variable transmission is provided on the rotating shaft 4A.

The drive pulley 7 is fixed to the rotating shaft 4A and is fixed to the fixed conical plate 7A at a position facing the fixed conical plate 7A. And a movable conical plate 7B. Further, a hydraulic chamber 7C is formed on the back side of the movable conical plate 7B. The hydraulic chamber 7C includes a first chamber 7C1 and a second chamber 7C2, and the first chamber 7C1 and the second material 7C2 serve as a pressing force generating unit for displacing the movable conical plate 7B.
Thus, a double piston structure is configured.

The driving pulley 7 can be linked with the driven pulley 9 by a belt 8.

The driven pulley 9 is located on the output side when the driving pulley 7 is set as the input side of the rotational force, and the fixed pulley 9A is located on the side of the driving pulley 7 opposite to the movable conical plate 7B. The movable conical plate 9B is inserted into the boss portion of the fixed conical plate 9A so as to be movable in the axial direction.

Also in the driven pulley 9, a hydraulic chamber 9C1 is formed on the back of the movable conical plate 9B.
The groove width can be changed in cooperation with the drive pulley 7 by hydraulic control in the inside. And this hydraulic chamber 9C
1 and a movable wall 9C2 sandwiching the movable wall is a centrifugal balance chamber, and a movable conical plate 9B is formed by an axial component of centrifugal hydraulic pressure generated by rotation of hydraulic oil in the hydraulic chamber 9C1.
And the movable conical plate 9B can be held at the set position by canceling the force for displacing the position.

The fixed cone plate 9 of the driven pulley 9
A is integrally provided with a driven shaft 10, and a driven gear 11 is attached to the driven shaft 10. The drive gear 11 is connected to the final gear 16 of the differential gear mechanism 17 connected to the output shafts 14 and 15 via the idle gears 12 and 13 to output the rotational force from the drive pulley 7 side. It can transmit to the shafts 14 and 15.

On the other hand, FIG. 1 shows a hydraulic control structure of the drive pulley 7 and the driven pulley 9 in the hydraulic chambers 7C and 9C in the above-described continuously variable transmission. Note that, in FIG. 1, the numbers shown in the circles indicate the hydraulic system.

FIG. 1 shows the mode of each valve when the position of the select lever provided in the driver's seat is set to a neutral state.

That is, the hydraulic control structure in the present embodiment is a structure in which a line pressure described later is directly introduced into a hydraulic chamber of a driven pulley. This structure is provided with an oil pump 18 and a regulation for adjusting line pressure.
A solenoid valve 20 for duty control, a speed ratio control valve 21, and a control pressure modulating valve 22 for regulating the supply pressure to each solenoid valve. The oil passage from the control pressure modulating valve 22
A damper clutch control valve 24 for controlling the supply of oil pressure to a damper clutch on the fluid coupling 2 side as an oil supply system to a solenoid valve 20 for duty control of line pressure, gear ratio and clutch pressure. And it is connected as a pilot pressure system to a clutch pressure control valve 25 for controlling the applied state of the clutch pressure.

On the other hand, in the line pressure system, in addition to the hydraulic chamber 9C1 of the driven pulley 9, a clutch pressure modulating valve 26 for setting the operating pressure of the clutch, and a switching valve, which will be described in detail later, constitute a switching valve. An oil passage leading to the hydraulic pressure sensor detection circuit switching valve 29 and the damper clutch control valve 24 is provided.

The solenoid 20 described above has one of them.
The individual 20A applies a duty control pressure to the transmission ratio control valve 21 to control the supply and discharge of oil to and from the hydraulic chamber 7C1 of the drive pulley 7, thereby adjusting the groove width of the pulley. That is, the gear ratio is controlled. The solenoid 20B controls the line pressure by applying a duty control pressure to the regulator valve 19 for adjusting the line pressure. The reference pressure at the time of performing the feedback control for the duty control is determined by a control unit shown in FIG.
(TCU) 50.

At the discharge port of the clutch pressure control valve 25 described above, an oil passage to an operation mode selection manual valve 28 for switching the oil passage to the forward clutch 6 and the reverse brake 5 is provided. It is connected. The operation mode select manual valve 28 has a structure that can be linked to a select lever operated by the driver. In the manual valve 28, the land portion of the spool included therein moves forward from the neutral position (N) in the figure toward the right side.
When it moves in the direction (D), an oil supply oil path from the clutch pressure control valve 25 to the forward clutch 6 is set, and the above-described land moves backward from the neutral position shown in the figure to the left.
Moving in the (R) direction, an oil supply oil passage from the clutch pressure control valve 25 to the reverse brake 5 is set.

Further, the control pressure module described above is used.
A part of the oil passage from the valve 22 is connected so as to act on one end face of a hydraulic sensor detection circuit switching valve 29 described later. That is, the hydraulic sensor detection circuit switching valve 2
Numeral 9 is configured to switch between detection of the line pressure and detection of the output pressure from the clutch pressure control valve 25. By detecting the line pressure, a feedback reference value for adjusting the groove width of the driven pulley 9 is calculated, and the clutch pressure is detected by detecting the output pressure from the clutch pressure control valve 25. A feedback reference value of the duty control pressure of the control solenoid valve 20C is calculated.

The determination of these reference values is shown in FIG.
Is performed by a control unit (TCU) 50 shown in FIG.
From (TCU) 50, each solenoid valve 20A, 20B,
An operation signal to 20C is output.

The hydraulic sensor detection circuit switching valve 29 includes:
An oil passage 31 branching from an output oil passage 30 extending from the clutch pressure control valve 25 to the operation mode selection manual valve 28 and an oil passage 34 capable of introducing line pressure are provided as input oil passages. The oil pressure detection oil passage 36 in which the oil passage 35 is disposed is connected as an oil passage on the output side. As shown in FIG. 3, the communicating state of each of these oil passages is set by a land portion of a spool 29A that is movable in the axial direction. Further, a connection structure in which the output pressure of the clutch control solenoid valve 20C via the control switching valve 27 acts on the opposite end face of the spool 29A to the oil passage from the control pressure modulation valve 22 described above. I have.

In FIG. 1, when the operation mode select manual valve 28 is at the neutral position, the solenoid valve 2 is connected via the clutch control pressure switching valve 27.
The duty control pressure from 0C is applied to the clutch pressure control valve 25 in the state of the highest pressure. Accordingly, in FIG. 3, the spool 29A of the hydraulic sensor detection circuit switching valve 29 is located below the center line against the oil pressure from the control pressure modulating valve 22 and the bias of the spring in the axial direction. As shown in the figure, it has been moved to the right.

When the spool 29A is in the above-described position, the land portion provided on the spool 29A causes the oil passage described above to be located below the center line in FIG. Thus, the output oil passage 3 of the clutch pressure control valve 25
The oil path 31 branched from 0 and the oil pressure detection oil path 36 communicate with each other to set a state in which another oil path is shut off.

In this state, the output pressure from the clutch pressure control valve 25 can be detected by the hydraulic pressure sensor 35 disposed in the hydraulic pressure detection oil passage 36. And the driving mode
When the manual select valve 28 is displaced to the “D” or “R” range, the output pressure from the clutch pressure control valve 25 detected by the hydraulic pressure sensor 35 is applied to the solenoid valve 20.
The control unit 50 serves as a reference value for setting the duty ratio of C.
Feedback. The control unit 50 lowers the duty ratio based on the feedback pressure and controls the communication state between the clutch pressure modulating valve 26 and the output oil passage 30 in the clutch pressure control valve 25. The output pressure is gradually increased to suppress the occurrence of clutch engagement shock due to a sudden change in pressure.

Therefore, when the operation mode select manual valve 28 is displaced from the neutral position to the "D" position, the output pressure from the clutch pressure control valve 25 changes the oil pressure detection oil at the oil pressure sensor detection circuit switching valve 29. The pressure is taken into the passage 36, and pressure detection for duty control of the solenoid valve 20C is performed by the hydraulic pressure sensor 35.

On the other hand, when the duty ratio of the solenoid valve 20C decreases and the output pressure (S1A) decreases, the spool 29A of the hydraulic sensor detection circuit switching valve 29 moves to the left as shown by the upper half of the center line in FIG. It will be in a moved state,
The line pressure circuit 19 communicates with the hydraulic pressure sensor circuit 36.

When the operating pressure to the forward clutch 6 is increased while the sudden increase in pressure is suppressed by setting the operating pressure of the clutch via the duty ratio setting of the solenoid valve 20C, the clutch control is started as shown in FIG. The pressure from the oil passage 37 branching from the oil passage leading to the forward clutch 6 with respect to the switching valve 27 increases. Therefore, the spool of the clutch control pressure switching valve 27 is displaced rightward in the drawing, and the pressure application from the solenoid valve 20C to the clutch pressure control valve 25 is not performed. For this reason, in the hydraulic sensor detection circuit switching valve 29, the sp
29A is displaced leftward in FIG.

The position of the spool 27A at this time is determined by the following equation. _{P 1A × A 1 = P 6} × A 2 + F S -kx However, P _1A: clutch pressure Mojure - pressure DOO valve, A _1:
Clutch pressure Mojure - sectional area of the surface receiving the pressure from the preparative valve 26, P _6: working pressure of the forward clutch 6, F _S: spool - Condition Le is in Figure 3, which is shown in the lower half of the valve center line , K: spring constant, x: spool is the displacement from the state shown in the upper half of the valve center line in FIG.

Accordingly, as the operating pressure of the forward clutch 6 increases, of the oil passages in the oil pressure sensor detection circuit switching valve 29, the line pressure introduction oil passage 34 and the oil pressure detection oil passage 36
And the other oil passages are cut off, and this state is maintained by the spool balancing according to the above equation.

In this state, the control is switched to the connection control of the damper clutch via the duty control from the solenoid valve 20C to the damper clutch control valve 24, and the line pressure is changed to the oil pressure sensor via the oil pressure detection oil passage 36. 3
5 is detected.

By the way, the communication state between the line pressure introduction oil passage 34 and the oil pressure detection oil passage 36 obtained when the equilibrium state of the spool 29A in the oil pressure sensor detection circuit switching valve 29 is set is as follows. As described above, the state in which the line pressure is detected can be set. At this time, the pressure regulated by the regulator valve 19 is directly input to the line pressure.

That is, by detecting this line pressure,
The groove width of the pulley at the time of constant speed traveling, especially the pressure setting to the hydraulic chamber of the driven pulley directly operated by the line pressure, the hydraulic pressure indicating the same value as the pressure applied to this hydraulic chamber This can be optimized by the control unit 50 based on the oil pressure in the detection oil passage 36.

Therefore, unless the select lever is moved from the "D" range to the "N" (P) range, the control pressure switching valve 27 does not return to the original state, and the hydraulic sensor switching valve 29 does not return to the original state. At this time, the line pressure detection state is continued. When the select lever is moved to the "N" range, the hydraulic pressure sensor switching valve 29 switches to the clutch pressure detecting circuit immediately.

Since the present embodiment has the above structure,
Oil from the oil pump 18 is supplied to the regulator valve 19.
And is supplied to each valve. The oil with the line pressure set is set to the operating pressure of the clutch by the clutch pressure modulating valve 26 and supplied to the clutch pressure control valve 25 and the clutch control pressure switching valve 27.

Clutch control pressure switching valve 2
At 7, the operation mode via the clutch pressure control valve 25 depends on the operating position of the operation mode selection manual valve 28.
The pressure applied to the manual valve 28
The spool 29A in the hydraulic pressure sensor detection circuit switching valve 29 is displaced by the displacement of the spool in accordance with the change in the operating pressure on the forward clutch 6 side by this control, and is controlled via the solenoid valve 20C. Clutch pressure control valve 25
The detection state of the reference pressure for duty control of the pressure applied to the sensor and the detection state of the line pressure are switched and set.

Accordingly, during the constant speed operation in which the forward clutch is completely engaged and the pressure in the spool in the hydraulic pressure sensor detection circuit switching valve 29 is obtained, the spool in the hydraulic pressure sensor detection circuit switching valve 29 is operated. Based on the displacement, the line pressure is detected at the same pressure as the value regulated by the regulator valve 19, and this detected value is executed by the control unit 50 at the duty for setting the groove width of the pulley. It can be used as a reference value for control.

[0057]

As described above, according to the present invention, the clutch for performing the duty control of the clutch operating pressure separately from the oil passage for applying the oil of the clutch operating pressure set by the clutch modulator valve. A hydraulic pressure sensor detection circuit switching valve to which a pressure from the control pressure switching valve and an output pressure from the clutch pressure control valve are applied;
An oil passage that can directly detect the line pressure from the stage where the forward clutch is engaged can be provided in the switching valve. For this reason, the line pressure can be detected with the same value as the value regulated by the regulator valve. Accordingly, by using the hydraulic pressure sensor for controlling the clutch pressure in the clutch control pressure switching valve also for detecting the line pressure, the cost can be reduced because the hydraulic pressure sensor is not dedicated to the line pressure detection.

According to the present invention, the oil pressure detection oil passage to the oil pressure sensor is connected to the oil pressure sensor detection circuit switching valve, and the hydraulic pressure detection oil passage is connected to the clutch until the forward clutch is engaged. It can be configured to be able to communicate with the output oil passage of the pressure control valve. Therefore, when the clutch starts to be engaged, the pressure rise can be adjusted by the duty control from the solenoid valve using the output pressure from the clutch pressure control valve, so that the shift shock due to the rapid pressure rise can be suppressed, and During traveling, it is possible to detect the pressure of the purifier in almost the entire area.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram for explaining a hydraulic control mechanism according to an embodiment of the present invention.

FIG. 2 is a model diagram showing an example of a structure of a continuously variable transmission to which the hydraulic control mechanism shown in FIG. 1 is applied.

FIG. 3 is a model diagram for explaining a structure and operation of a main part in the hydraulic control mechanism shown in FIG. 1;

FIG. 4 is a block diagram for explaining a control unit used in the hydraulic control mechanism shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 2 Fluid coupling which forms an automatic transmission 7 Drive pulley 8 Belt 9 Follower pulley 19 Regulator valve 20C Solenoid valve for controlling clutch pressure duty 25 Clutch pressure control valve 26 Clutch pressure modulate Valve 27 Clutch control pressure switching valve 28 Manual valve for operation mode selection 29 Hydraulic sensor detection circuit switching valve 29A spool 31 Oil passage branched from clutch operation pressure supply oil passage 33 Supply oil for duty control pressure Oil passage branched from the line 34 Line pressure introduction oil passage 35 Oil pressure sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-341654 (JP, A) JP-A-5-79550 (JP, A) JP-A-4-203666 (JP, A) JP-A-59-1979 19755 (JP, A) JP-A-64-44346 (JP, A) JP-A-59-75840 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 59/00-61 / 12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (2)

(57) [Claims] A forward / reverse switching device comprising a friction element;
In a hydraulic control device for a continuously variable transmission that performs a continuously variable transmission by changing a pulley width of a driving pulley and a driven pulley by hydraulic pressure and changing a winding diameter of an endless belt stretched between both pulleys, A regulator valve that regulates a discharge pressure from a hydraulic pressure source; a clutch pressure control valve that regulates a hydraulic pressure supplied to the friction element; and detects a hydraulic pressure supplied to the friction element and a hydraulic pressure regulated by the regulator valve. A hydraulic pressure detecting means, and a switching valve for switching and connecting the hydraulic pressure detecting means to a first oil passage connected to the regulator valve or a second oil passage connected to the friction element. Hydraulic control device for step transmission. 2. A forward / reverse switching device comprising a friction element,
In a hydraulic control device of a continuously variable transmission that performs a continuously variable transmission by changing a pulley width of a driving pulley and a driven pulley by hydraulic pressure and changing a winding diameter of an endless belt stretched between both pulleys, A regulator valve for regulating a discharge pressure from a hydraulic pressure source, a first solenoid valve for controlling the regulator valve, a clutch pressure control valve for regulating a hydraulic pressure supplied to the friction element, and a second valve for controlling the clutch pressure control valve. A two-solenoid valve, hydraulic pressure detecting means for detecting a hydraulic pressure supplied to the friction element and a hydraulic pressure regulated by the regulator valve, and a first oil passage or the friction connecting the hydraulic pressure detecting means to the regulator valve A switching valve for switching and connecting to a second oil passage connected to the element, and the oil pressure detecting means being connected to the first oil passage by the switching valve. When the first solenoid valve is feedback-controlled in accordance with the detection value of the oil pressure detection means, the switching valve is connected to the detection value of the oil pressure detection means when the oil pressure detection means is connected to the second oil passage. Control means for feedback-controlling the second solenoid valve in response to the control signal.