JP2021063534A - Hydraulic controller of continuously variable transmission - Google Patents

Abstract

To provide a hydraulic controller of a continuously variable transmission capable of more reliably maintaining a low ratio as a transmission ratio of a belt type continuously variable transmission, and capable of obtaining smooth and excellent start performance of a vehicle, upon starting the vehicle.SOLUTION: A hydraulic controller comprises a pressure regulating valve that regulates the pressure of oil supplied to a drive pulley, a control valve that controls the pressure of oil supplied by the pressure regulating valve, and a control unit that controls a current value supplied to the control valve. The hydraulic controller has, as an indicated value of the current supplied to the control valve, a functional protection lower limit value IA that is a value at which the hydraulic pressure on a low pressure side can be secured. When it is necessary to secure a transmission ratio of a predetermined value or less as a transmission ratio of a continuously variable transmission, the control unit performs low-hydraulic current instruction control of instructing a current value IB that exceeds the functional protection lower limit value IA to the low pressure side.SELECTED DRAWING: Figure 3

Description

The present invention relates to a hydraulic control device for a continuously variable transmission.

Conventionally, a belt-type continuously variable transmission (CVT) composed of a movable drive pulley (DR pulley) and a driven pulley (DN pulley) and an endless metal belt wound around these two pulleys is known. Has been done. Patent Document 1 discloses a hydraulic circuit using a linear solenoid valve as a configuration for controlling the pressure of the belt pressing hydraulic control valve in a belt-type continuously variable transmission.

By the way, in a vehicle equipped with a belt-type continuously variable transmission as described above, when the engine is started from the stopped state (soak) of the engine which is the driving source of the vehicle and the vehicle is started immediately after that, it is smooth. Moreover, in order to exhibit good starting performance, it is necessary to surely maintain a low ratio (the value of the smallest gear ratio) as the gear ratio (ratio) of the continuously variable transmission at the time of starting. However, as a characteristic of the belt and pulley of the belt type continuously variable transmission, even when the belt and pulley are stationary, the oil pressure of the drive pulley is larger than that of the driven pulley, and the differential pressure between them is large. If the / thrust ratio becomes large, the gear ratio becomes a value slightly larger than the smallest value, which may cause a phenomenon that the low ratio cannot be maintained (the ratio is separated from the low ratio).

Further, for example, in an oil passage from a hydraulic (oil) supply source, the oil chamber of the drive pulley is on the front side of the oil passage and the oil chamber of the driven pulley is on the back side, so that the oil chamber of the drive pulley is reached. If the distance is shorter than the distance to the oil chamber of the driven pulley, the oil that reaches the oil chamber of the drive pulley may raise the oil pressure of the drive pulley first. Even in such a case, it may be one of the causes that the low ratio cannot be maintained as described above.

The specifications that determine the output of the flood control of the belt-type continuously variable transmission include the current supplied to the control valve (linear solenoid valve) for adjusting the flood control supplied to the oil chamber of the drive pulley and the oil chamber of the driven pulley. By instructing the value of, the relevant oil pressure is output. In this case, at present, in order to protect the function of the continuously variable transmission, the specifications are such that only the current value (lower limit value of functional protection) that can secure the oil pressure on the low voltage side is specified, including the variation in the oil pressure value for each product. ing.

Therefore, in particular, when the oil pressure of the drive pulley is indicated by the above-mentioned lower limit value of functional protection, it may not be possible to sufficiently reduce the oil pressure of the drive pulley to the oil pressure required to maintain the low ratio. Therefore, as described above, there is a risk that the low ratio cannot be maintained when the vehicle starts.

Japanese Unexamined Patent Publication No. 11-182666

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to more reliably maintain a low ratio as a gear ratio of a belt-type continuously variable transmission when the vehicle starts. It is an object of the present invention to provide a hydraulic control device for a continuously variable transmission, which can obtain smooth and good starting performance of a vehicle.

In order to achieve the above object, the hydraulic control device according to the present invention includes a movable drive pulley (5) and a driven pulley (8) mounted on a vehicle, and an endless belt wound around these two pulleys. A hydraulic control device for a continuously variable transmission including a belt-type continuously variable transmission (100) composed of 7) and a hydraulic control device (110) for controlling the continuously variable transmission (100). The hydraulic control device (110) is a pressure adjusting valve (152a) for adjusting the pressure supplied to the drive pulley (5) and a control valve for controlling the oil supply supplied by the pressure adjusting valve (152a). (168a) and a control unit (180) for controlling the current value supplied to the control valve (168a) are provided, and the low pressure side oil pressure is secured as an indicated value of the current supplied to the control valve (168a). When it is necessary to secure a gear ratio of a predetermined value or less as a gear ratio of the continuously variable transmission (100), the control unit (180) has a functional protection lower limit value (IA) which is a possible value. It is characterized in that low-hydraulic current instruction control for instructing a current value (IB) exceeding the lower limit value (IA) of functional protection to the low pressure side is performed.

According to the hydraulic control device for a continuously variable transmission for a vehicle according to the present invention, when it is necessary to secure a gear ratio equal to or less than a predetermined value as the gear ratio of the continuously variable transmission, the functional protection lower limit value (IA) is set to the low pressure side. By instructing the current value (IB) that exceeds the specified value, the oil pressure supplied to the drive pulley can be controlled more reliably, and the gear ratio of the continuously variable transmission is secured to be less than or equal to the predetermined value. You will be able to do it. As a result, the low ratio of the gear ratio can be secured more reliably.

Further, in this case, the low-hydraulic current instruction control may be performed when setting the gear ratio of the continuously variable transmission (100) when the vehicle starts. Further, in that case, the vehicle includes an engine (1) as a drive source, and the low-hydraulic current instruction control is performed when the vehicle starts after restarting from the stopped state of the engine (1). You may.

As described above, when the low ratio can be secured by performing the low-hydraulic current instruction control at the time of starting the vehicle after the engine is stopped (soaked), the following effects are obtained.

That is, the reduction of the work load of the engine when the vehicle starts has the effect of improving fuel efficiency. In addition, the climbing start performance of the vehicle can be improved. Further, by increasing the acceleration at the time of starting the vehicle, the acceleration performance of the vehicle can be improved and the driver's experience can be improved.

Further, the oil pressure control device (110) controls another pressure adjusting valve (152b) for adjusting the pressure supplied to the driven pulley (8) and the oil pressure supplied by the other pressure adjusting valve (152b). It also includes another control valve (168b) for the purpose and an oil passage (150) that communicates from the oil supply sources (120,130) to the pressure regulating valve (152a) and the other pressure regulating valve (152b). The oil passage (150) communicates with the pressure regulating valve (152a) on the front side close to the oil supply source and communicates with the other pressure regulating valve (152b) on the back side far from the oil supply source. May be.

The oil passage (150) from the oil supply source communicates with the pressure regulating valve (152a) that regulates the oil pressure supplied to the drive pulley (5) on the front side close to the oil supply source, and connects to the driven pulley (8). In a configuration in which the other pressure adjusting valve (152b) for adjusting the pressure of the supplied oil is communicated with the other pressure adjusting valve (152b) on the far side from the oil supply source, the drive pulley (5) is used when the low hydraulic current instruction control of the present invention is not performed. ), Therefore, there is a possibility that the low ratio of the gear ratio cannot be secured when the vehicle starts. On the other hand, in the present invention, by performing the above-mentioned low-hydraulic current instruction control, a gear ratio of a predetermined value or less is secured as the gear ratio of the continuously variable transmission even in the above-mentioned oil passage configuration. Therefore, it is possible to reliably secure a low ratio of the gear ratio when the vehicle starts. That is, the low-hydraulic current instruction control of the present invention is particularly effective as a control for ensuring a low ratio of gear ratios in the hydraulic control device having an oil passage configuration as described above.

The reference numerals in parentheses above indicate the drawing reference numbers of the corresponding components in the embodiments described later for reference.

According to the hydraulic control device for the continuously variable transmission according to the present invention, the low ratio can be more reliably maintained as the gear ratio of the belt-type continuously variable transmission when the vehicle starts, and the vehicle is smooth and good. It is possible to obtain a good starting performance.

It is a figure which shows typically the structure of the hydraulic control device of the belt type continuously variable transmission which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the hydraulic circuit of a hydraulic control device. It is a graph which shows the relationship between the current value of a control valve and the oil pressure of a drive pulley.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<Structure of hydraulic control device for continuously variable transmission>
FIG. 1 is a schematic view showing a configuration of a hydraulic control device for a continuously variable transmission according to an embodiment of the present invention. The configuration of the hydraulic control device for the continuously variable transmission will be described with reference to the figure. The hydraulic control device of this continuously variable transmission changes the pulley widths of the drive pulley 5 and the driven pulley 8 by changing the axial thrust applied to the drive pulley (DR pulley) 5 and the driven pulley (DN pulley) 8. It has a belt-type continuously variable transmission 100 that changes the gear ratio steplessly by causing the transmission, and a hydraulic control device 110 that controls the generation of axial thrust. The stepless transmission 100 controlled by the hydraulic control device 110 has an output shaft of the engine 1 as a drive source, a transmission input shaft 2 connected via a fluid torque converter 26, and a speed change arranged in parallel with the output shaft 2. It is composed of a machine counter shaft 3, a metal belt mechanism 4 arranged between the transmission input shaft 2 and the transmission counter shaft 3, and a forward / backward switching mechanism 20 arranged on the transmission input shaft 2. Will be done.

The metal belt mechanism 4 includes a drive pulley 5 rotatably arranged on the transmission input shaft 2 and a driven pulley 8 arranged on the transmission counter shaft 3 so as to rotate integrally with the transmission counter shaft 3. , These are composed of a drive pulley 5 and an endless metal belt 7 wound around the driven pulley 8.

The drive pulley 5 has a fixed side drive pulley half body 5A and a movable side drive pulley half body 5B. Here, the fixed side drive pulley half body 5A is arranged on the transmission input shaft 2 so as not to move in the axial direction. The movable side drive pulley half body 5B is configured to be movable relative to the fixed side drive pulley half body 5A in the axial direction. A cylinder chamber (DR cylinder chamber) 6 of the drive pulley 5 is formed on the side of the movable side drive pulley half body 5B, and the movable side drive pulley half body is formed by the hydraulic pressure supplied from the hydraulic control device 110 to the DR cylinder chamber 6. Axial thrust (drive pulley axial thrust) that moves 5B in the axial direction is generated.

The driven pulley 8 is composed of a fixed side driven pulley half body 8A and a movable side driven pulley half body 8B. Here, the fixed-side driven pulley half body 8A is arranged on the transmission counter shaft 3 so as not to move in the axial direction. The movable side driven pulley half body 8B is configured to be movable relative to the fixed side driven pulley half body 8A in the axial direction. A cylinder chamber (DN cylinder chamber) 9 of the driven pulley 8 is formed on the side of the movable side driven pulley half body 8B, and the movable side driven pulley half body is formed by the hydraulic pressure supplied from the hydraulic control device 110 to the DN cylinder chamber 9. Axial thrust (driven pulley axial thrust) that moves 8B in the axial direction is generated.

The hydraulic control device 110 sets an axial thrust that does not cause slip in the metal belt 7 by controlling the hydraulic pressure supplied to the DR cylinder chamber 6 and the DN cylinder chamber 9, and the pulley widths of the drive pulley 5 and the driven pulley 8. Can be set variably. As a result, the continuously variable transmission 100 can continuously (continuously) control the gear ratio by continuously changing the winding radius of the metal belt 7 with respect to both pulleys 5 and 8.

The forward / backward switching mechanism 20 includes a planetary gear mechanism PGS and a forward / backward switching clutch (forward clutch 24 and reverse clutch 25). The planetary gear mechanism PGS is a carrier 22 that rotates and revolves around a sun gear 21 coupled to a transmission input shaft 2, a ring gear 23 coupled to a torque converter, and a pinion 22a that meshes with the sun gear 21 and the ring gear 23. It consists of.

The reverse clutch 25 is configured so that the carrier 22 can be fixedly held to the casing Ca. The forward clutch 24 is configured so that the sun gear 21 and the ring gear 23 can be connected to each other. When the forward clutch 24 is engaged, the sun gear 21, the carrier 22, and the ring gear 23 rotate integrally with the transmission input shaft 2, and the drive pulley 5 (DR pulley) rotates in the same direction as the transmission input shaft 2 (forward). Driven in the direction). On the other hand, when the reverse clutch 25 is engaged, the carrier 22 is fixedly held by the casing Ca, and the ring gear 23 is driven in the direction opposite to that of the sun gear 21 (reverse direction).

The power of the engine 1 is changed via the metal belt mechanism 4 and the forward / backward switching mechanism 20 and transmitted to the transmission counter shaft 3. The power transmitted to the transmission counter shaft 3 is transmitted to the differential mechanism 29 via the gears 27a, 27b, 28a, 28b, and is transmitted from here to the left and right wheels (driving wheels) W (only one is shown).

FIG. 2 is a block diagram showing a configuration of a hydraulic circuit of the hydraulic control device 110. The hydraulic control device 110 has a first pump (mechanical pump) 120 that pumps oil (hydraulic oil) driven by the engine 1 and stored in the reservoir 118 through the oil passage 121 and pumps it. An oil passage 122 for flowing the oil pumped from the first pump 120 as the first oil is connected to the output side of the first pump 120.

A second pump 130 having a capacity smaller than that of the first pump 120 is connected to the downstream side of the oil passage 122. The second pump 130 is an electric pump that is driven by the rotation of the motor 140 and outputs the first oil supplied via the oil passage 122 as the second oil. In this case, the second pump 130 can pressurize the supplied first oil and pump the pressurized first oil as the second oil.

An oil passage 150 is connected to the output side of the second pump 130. The oil passage 150 is branched into two oil passages 150a and 150b on the downstream side. One oil passage 150a is connected to the drive pulley 5 (DR cylinder chamber 6) of the continuously variable transmission 100 via the regulator valve 152a and the oil passage 154a. The other oil passage 150b is connected to the driven pulley 8 (DN cylinder chamber 9) of the continuously variable transmission 100 via the regulator valve 152b and the oil passage 154b.

A bypass valve 159 is connected in parallel with the second pump 130 between the two oil passages 122 and 150. The bypass valve 159 is a valve provided so as to bypass the second pump 130, and by controlling the valve so as to open when the second pump 130 is stopped, the bypass valve 130 is bypassed and the oil passage 122 on the upstream side 122. Oil (first oil) can be circulated from the oil passage 150 on the downstream side.

A check valve 158 is connected in parallel with the first pump 120 between the two oil passages 121 and 122. The check valve 158 is a check valve provided so as to bypass the first pump 120, and allows oil (first oil) to flow from the upstream oil passage 121 to the downstream oil passage 122. On the other hand, the flow of oil (second oil) from the oil passage 122 on the downstream side to the oil passage 121 on the upstream side is blocked.

The oil passage 154b is provided with a side pressure sensor (hydraulic sensor) 162 that detects the oil pressure (pulley pressure which is the side pressure of the driven pulley 8) PDN supplied to the driven pulley 8.

A CR valve 164 is connected to the downstream side of the oil passage 150c branching from the oil passage 150. The upstream side of the CR valve 164 is connected to the oil passage 150c, and the downstream side is connected to the two control valves 168a and 168b via the oil passage 166. Further, the downstream side of the CR valve 164 (oil passage 166) is connected to the torque converter 26 and the forward / backward switching mechanism 20 (see FIG. 1) via another valve (not shown).

Each control valve 168a and 168b is a normally open type solenoid valve (linear solenoid valve) having a solenoid, and is in a valve closed state while a control signal (current signal) is supplied from the control unit 180 and the solenoid is energized. On the other hand, when the solenoid is not energized, the valve is opened.

One control valve 168a is a solenoid valve for the drive pulley 5, and in the valve open state, the oil supplied from the CR valve 164 via the oil passage 166 is supplied to the regulator valve 152a via the oil passage 174a. ..

The other control valve 168b is a solenoid valve for the driven pulley 8. In the valve open state, the oil supplied from the CR valve 164 via the oil passage 166 is supplied to the regulator valve 152b via the oil passage 174b. Supply.

Therefore, in one regulator valve 152a, the pressure of the oil supplied from the control valve 168a via the oil passage 174a is used as the pilot pressure, and the line pressure PH of the oil supplied through the oil passages 150 and 150a is equal to or higher than the predetermined pressure. If so, the valve is opened and the oil is supplied to the drive pulley 5 via the oil passage 154a. The other regulator valve 152b uses the pressure of the oil supplied from the control valve 168b via the oil passage 174b as the pilot pressure, and the line pressure PH of the oil supplied via the oil passages 150 and 150b is equal to or higher than the predetermined pressure. If so, the valve is opened and the oil is supplied to the driven pulley 8 via the oil passage 154b.

In the present embodiment, the regulator valve 152a (“pressure adjusting valve” of the present invention) for the drive pulley 5 and the regulator for the driven pulley 8 from the first pump 120 and the second pump 130 (“oil supply source” of the present invention) The oil passage 150 communicating with the valve 152b (“another pressure regulating valve” of the present invention) communicates with the regulator valve 152a for the drive pulley 5 on the front side (upstream side) close to the first pump 120 and the second pump 130. Then, it communicates with the regulator valve 152b for the driven pulley 8 on the back side (downstream side) far from the first pump 120 and the second pump 130. Further, the oil passage length from the first pump 120 and the second pump 130 to the regulator valve 152b for the driven pulley 8 is shorter than the oil passage length to the regulator valve 152 for the drive pulley 5. As a result, the oil supplied from the first pump 120 and the second pump 130 reaches the regulator valve 152a for the drive pulley 5 before the regulator valve 152b for the driven pulley 8.

In the hydraulic control device of the present embodiment, by instructing the current values to be passed through the control valves (linear solenoid valves) 168a and 168b for adjusting the oil pressure supplied to the oil chamber of the drive pulley 5 and the oil chamber of the driven pulley 8. , The relevant oil pressure is output. Then, as an indicated value of the current supplied to the control valve 168a, there is a functional protection lower limit value (current value IA described later) which is a current value that can secure the oil pressure on the low voltage side. On the other hand, when it is necessary to secure a gear ratio equal to or less than a predetermined value as the gear ratio of the continuously variable transmission 100, low hydraulic current instruction control for instructing a current value exceeding the functional protection lower limit value to the low voltage side. Is supposed to do. Hereinafter, this low-hydraulic current instruction control will be described in detail.

FIG. 3 is a graph showing the relationship between the current I (indicated value) supplied to the control valve 168a and the oil pressure P of the drive pulley 5. In the graph of the figure, the upper limit line L1 and the lower limit line L2 of the variation of the oil pressure P of the drive pulley 5 with respect to the current I (indicated value), and the instructed value (command value) of the oil pressure in the case of the oil pressure instruction instead of the current instruction Line L3 and. As shown in the line L3 of the command value of the oil pressure, the function of the continuously variable transmission 100 is between the value of the oil pressure instruction (the oil pressure instruction value) and the value of the oil pressure actually generated based on the value (the oil pressure instruction value). There is a predetermined amount of difference (margin) M provided for protection.

Here, in order to maintain the low ratio of the drive pulley 5 when the vehicle starts after restarting from the stopped state of the engine 1, it is necessary that the oil pressure P of the drive pulley 5 is P1 or less (P <P1). is there.

Then, when the line L3 of the command value of the hydraulic pressure becomes 0, that is, when the command value of the hydraulic pressure is the lowest command value = 0, the current value IA (lower limit value of functional protection) can secure the hydraulic pressure on the low voltage side. It is the lower limit of functional protection, which is the current value. Therefore, in the normal hydraulic control of the continuously variable transmission 100, the hydraulic control of the drive pulley is performed using only the current value equal to or less than this current value IA, and the range of the current value exceeding the current value IA (current value IA). The current value that exceeds the low pressure side) is not used.

However, as shown in the graph of FIG. 3, in the oil pressure P corresponding to the current value IA (functional protection lower limit value) when the command value L3 of the oil pressure is the lowest command value = 0, the oil pressure P varies. The upper limit value S1 exceeds the value P1 of the oil pressure that can maintain the low ratio. Therefore, there is a possibility that the low ratio of the continuously variable transmission 100 cannot be secured even if the current value IA when the command value of the oil pressure is the lowest command value = 0 is specified in the normal hydraulic control.

Therefore, in the hydraulic control device of the present embodiment, when the vehicle starts after restarting from the stopped state of the engine 1, the indicated value of the hydraulic pressure is the lowest indicated value as the current I (indicated value) supplied to the control valve 168a. The current value IB that exceeds the current value IA (functional protection lower limit value) when = 0 is set to the low voltage side. In this way, when the current indicated value is IB, the upper limit value S2 of the variation in the oil pressure does not exceed the value P1 of the oil pressure that can maintain the low ratio, so that the oil pressure of the drive pulley 5 can maintain the low ratio. It can be within the range of the oil pressure value (P <P1).

As described above, according to the hydraulic control device of the present embodiment, when it is necessary to secure a low ratio (a gear ratio equal to or less than a predetermined value referred to in the present application) as a gear ratio of the continuously variable transmission 100, a functional protection lower limit value. By instructing the current value (IB) that exceeds (IA) to the low pressure side, the oil pressure supplied to the drive pulley 5 can be controlled more reliably, and the gear ratio of the continuously variable transmission 100 is predetermined. It will be possible to secure a gear ratio below the value (here, the gear ratio required to maintain the low ratio).

Then, when the low ratio can be secured by performing the above-mentioned low-hydraulic current instruction control at the time of starting the vehicle after the engine 1 is stopped (soaked), the following effects are obtained.

That is, since the work load of the engine 1 when the vehicle starts is reduced, there is an effect of improving fuel efficiency. In addition, the climbing start performance of the vehicle can be improved. Further, by increasing the acceleration at the time of starting the vehicle, the acceleration performance of the vehicle can be improved and the driver's experience can be improved.

Further, the hydraulic control device 110 of the present embodiment includes an oil passage 150 communicating from the first pump 120 and the second pump 130 to the regulator valve 152a and the regulator valve 152b, and the oil passage 150 includes the first pump 120 and It communicates with the regulator valve 152a on the front side close to the second pump 130, and communicates with the regulator valve 152b on the back side far from the first pump 120 and the second pump 130.

In this configuration, if the above-mentioned low-hydraulic current instruction control is not performed, the oil supply to the drive pulley 5 rises first, so that the low ratio of the gear ratio may not be secured when the vehicle starts. .. On the other hand, in the hydraulic control device of the present embodiment, by performing the above-mentioned low-hydraulic current instruction control, the low ratio can be maintained as the gear ratio of the continuously variable transmission even in the above-mentioned oil passage configuration. The required gear ratio can be secured. That is, the low-hydraulic current instruction control of the present embodiment is particularly effective as a control for ensuring a low ratio of the gear ratio in the hydraulic control device having an oil passage configuration as in the present embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are made within the scope of claims and the technical ideas described in the specification and drawings. Is possible.

For example, in the above embodiment, the case where the above-mentioned low-hydraulic current instruction control is performed at the time of starting the vehicle, particularly at the time of starting the vehicle after restarting from the stopped state of the engine 1, has been shown. It may be performed at a timing other than when the vehicle starts after restarting from the stopped state of the engine 1, or when setting the gear ratio of the continuously variable transmission 100 other than when the vehicle starts. It may be.

Further, in the above embodiment, the oil passage 150 communicates with the regulator valve 152a on the front side close to the first pump 120 and the second pump 130, and the regulator valve 152b on the back side far from the first pump 120 and the second pump 130. However, the case is not limited to this configuration, and the oil passage 150 communicates with the regulator valve 152b on the front side close to the first pump 120 and the second pump 130, and the first pump 120 And it may be configured to communicate with the regulator valve 152a on the far side from the second pump 130.

1 engine (drive source)
2 Transmission input shaft 3 Transmission counter shaft 4 Metal belt mechanism 5 Drive pulley 6 Cylinder chamber (DR cylinder chamber)
7 Metal belt 8 Driven pulley 9 Cylinder chamber (DN cylinder chamber)
20 Forward / backward switching mechanism 24 Forward clutch 25 Reverse clutch 26 Torque converter 29 Differential mechanism 100 Continuously variable transmission 110 Hydraulic control device 120 First pump (oil supply source)
130 Second pump (oil supply source)
152a Regulator valve (pressure regulating valve)
152b Regulator valve (other pressure control valve)
158 Check valve 159 Bypass valve 164 CR valve 168a Control valve 168b Control valve (other control valves)
180 Control unit (control unit)

Claims (4)

A belt-type continuously variable transmission consisting of a movable drive pulley and a driven pulley mounted on a vehicle and an endless belt wound around these two pulleys.
A hydraulic control device for a continuously variable transmission including a hydraulic control device for controlling the continuously variable transmission.
The hydraulic control device is
A pressure regulating valve that regulates the hydraulic pressure supplied to the drive pulley,
A control valve for controlling the flood control supplied by the pressure regulating valve, and
A control unit that controls the current value supplied to the control valve is provided.
As an indicated value of the current supplied to the control valve, it has a functional protection lower limit value which is a value that can surely secure the oil pressure on the low voltage side.
When it is necessary to secure a gear ratio of a predetermined value or less as the gear ratio of the continuously variable transmission, the control unit performs low-hydraulic current instruction control for instructing a current value exceeding the functional protection lower limit value to the low voltage side. A hydraulic control device for a continuously variable transmission, characterized in that it is performed. The hydraulic control device for a continuously variable transmission according to claim 1, wherein the low-hydraulic current instruction control is performed when setting the gear ratio of the continuously variable transmission when the vehicle starts. The vehicle is equipped with an engine as a drive source.
The hydraulic control device for a continuously variable transmission according to claim 2, wherein the low-hydraulic current instruction control is performed when the vehicle starts after the engine is restarted from a stopped state. The hydraulic control device is
With other pressure regulating valves that regulate the hydraulic pressure supplied to the driven pulley,
With the other control valve for controlling the oil supply supplied by the other pressure regulating valve,
It is provided with an oil passage that communicates from the oil supply source to the pressure regulating valve and the other pressure regulating valve.
Claim 1 is characterized in that the oil passage communicates with the pressure adjusting valve on the front side close to the oil supply source and communicates with the other pressure adjusting valve on the back side far from the oil supply source. The hydraulic control device for a continuously variable transmission according to any one of items 3 to 3.

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