JP2003262267A - Internally enclosed pressure control device for variable transmission mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly reduce internally enclosed pressure in a variable transmission mechanism without generating a slip in the variable transmission mechanism. <P>SOLUTION: The internally enclosed pressure control device reduces the internally enclosed pressure for the variable transmission mechanism from designated pressure to pressure lower than the designated pressure within a range having no slip. A load for a power source of a vehicle mounting the variable transmission mechanism or a physical value varied in proportion to the load for any rotary member for forming a driving system including the variable transmission mechanism are controlled within a designated range. The internally enclosed pressure control device comprises the steps (Steps S1 and S2) of: permitting the internally enclosed pressure for reducing toward the lower pressure if a permission condition, in which rotary acceleration of any rotary member for forming the driving system is within a predetermined range, is effected; and prohibiting the internally enclosed pressure for reducing toward the lower pressure if the permission condition is not effected. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a belt-type or traction-type (toroidal-type) continuously variable transmission mechanism, and more particularly, it controls a clamping force for clamping a member for transmitting torque such as a belt or a power roller. It is related to the device.

[0002]

2. Description of the Related Art A conventionally known continuously variable transmission mechanism has a frictional force between a belt and a pulley and a shearing force of traction oil interposed between a power roller and each disk on the input / output side. It is configured to utilize and transmit torque. Then, the torque capacity that can be transmitted is set to a capacity corresponding to the contact pressure between the belt and the pulley (that is, the clamping pressure of the belt by the pulley) and the clamping pressure with which each disk clamps the power roller.

Therefore, if the clamping pressure for clamping the torque transmitting member such as the belt or the power roller is increased, the torque capacity becomes large with respect to the input torque, so that excessive slippage of the belt or the like occurs. Instead, torque can be transmitted and a predetermined gear ratio can be set. However, when the clamping pressure is high, the power transmission efficiency is reduced, which causes deterioration of fuel efficiency. Therefore, it is preferable that the clamping pressure in the continuously variable transmission mechanism is as low as possible within a range in which excessive slip does not occur.

By the way, the output torque of a power source such as an engine changes in accordance with the running state of the vehicle, and in the case of sudden acceleration, the output torque of the power source, that is, the input torque to the continuously variable transmission mechanism is It may change rapidly. Further, even when the vehicle is pushed up due to the unevenness of the road surface, the torque transmitted in the continuously variable transmission mechanism changes greatly.

When the torque acting on or transmitted to such a continuously variable transmission mechanism changes, if the belt clamping pressure becomes low, excessive slippage occurs in the continuously variable transmission mechanism and its durability deteriorates. Sometimes. In order to avoid such an inconvenience, for example, Japanese Patent Laid-Open No. 2001-24154
In the invention described in Japanese Patent Publication No. 0, the running environment is detected, and the fluctuation of the torque is predicted according to the detected running environment to predict a sudden change in the throttle opening or a sudden acceleration. It is predicted that the torque is likely to fluctuate in an environment where the vehicle is running on a highway and is not in a favorable environment where there is no vehicle ahead, or when there is no vehicle ahead when the vehicle is stopped. In the opposite case, the clamping pressure is reduced.

[0006]

Therefore, in the invention described in the above publication, the clamping pressure is reduced when a rapid change in the throttle opening or a rapid acceleration is not predicted. Therefore, for example, when the vehicle is traveling on a flat road where a particularly large driving force is not required, the clamping pressure is reduced. However, when the driving wheels slip, the continuously variable transmission mechanism uses inertia torque due to the tire grip after that. Slippage may occur.

As described above, in the inventions described in the above publications, there are many opportunities to reduce the clamping pressure, which is advantageous for improving fuel efficiency, but the clamping pressure is relatively low depending on the running state of the vehicle. As a result, the continuously variable transmission mechanism may slip and wear.

The present invention has been made in view of the above technical problems, and it is an object of the present invention to provide a control device capable of reducing the clamping pressure while surely avoiding slippage in a continuously variable transmission mechanism. It is intended.

[0009]

In order to achieve the above object, the present invention relates to a load acting on a drive system including a continuously variable transmission mechanism or a power source to which the continuously variable transmission mechanism is connected. It is characterized in that it is configured to execute control for reducing the clamping pressure to the extent that slip does not occur in the continuously variable transmission mechanism, based on the load and the rotational acceleration of any rotating member that constitutes the drive system thereof. To do. Specifically, in the invention of claim 1, the clamping pressure of the continuously variable transmission mechanism in which the torque capacity changes in accordance with the clamping pressure that clamps the torque transmitting member is set within a range in which the torque transmitting member does not slip. In a pinching pressure control device for a continuously variable transmission mechanism that reduces the pressure from the pressure to a pressure lower than the pressure, a load of a power source of a vehicle in which the continuously variable transmission mechanism is mounted or a drive system including the continuously variable transmission mechanism is configured. The physical quantity that changes according to the load of any of the rotating members is within a predetermined range, and the rotational acceleration of any of the rotating members forming the drive system is within a predetermined range. When the permitting condition within is satisfied, the clamping pressure is allowed to be reduced to the low pressure, and when the permitting condition is not satisfied, the clamping pressure is not allowed to be reduced to the low pressure. That it comprises a means for a clamping force control device according to claim.

Therefore, according to the invention of claim 1, when the load of the power source or any of the rotating members or the physical quantity related thereto is within a predetermined range and the rotational acceleration of any of the rotating members is equal to or less than a predetermined value. , The clamping force is reduced. Further, when such a condition is not satisfied, the reduction of the clamping pressure is prohibited. Here, the reduction of the clamping pressure is, for example, a clamping pressure with a small excess amount with respect to the minimum clamping pressure at which the continuously variable transmission does not slip in the running state or the driving state of the vehicle at that time, in other words, This control is to reduce the margin of torque capacity with respect to the torque capacity at which slippage occurs. Therefore, according to the first aspect of the present invention, for example, even when the accelerator opening is small, when the rotational acceleration of the rotating member becomes large due to tire slip or the like, the clamping pressure is not lowered, and when the accelerator opening is large when climbing a hill. Since the clamping force cannot be reduced due to the large load, slipping of the continuously variable transmission mechanism is reliably avoided, and in other states, the clamping pressure is reduced and the power transmission efficiency is improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the continuously variable transmission mechanism is connected in series in the torque transmission direction, and the torque transmission member in the continuously variable transmission mechanism slips. A clutch mechanism that is set to a torque capacity excess amount that is smaller than a torque capacity excess amount with respect to the generated torque capacity, and when the clamping pressure is increased from the low pressure because the permission condition is no longer satisfied and the permission condition is satisfied. When the clamping pressure is reduced to the low pressure by the pressure adjusting means for maintaining the magnitude relation of the torque capacity excess amount in the transitional state of the variation of the clamping pressure and changing the clamping pressure and the torque capacity of the clutch mechanism. The pinching pressure control device is characterized by further comprising:

Therefore, according to the second aspect of the invention, when the torque acting on the drive system including the continuously variable transmission mechanism and the clutch mechanism is increased, the excess amount of the torque capacity with respect to the torque capacity that causes slippage, that is, the margin of the torque capacity. However, since the clutch mechanism is smaller than the continuously variable transmission mechanism (or the transmission torque of the clutch mechanism is smaller than the transmission torque of the continuously variable transmission mechanism), slippage occurs in the clutch mechanism prior to the continuously variable transmission mechanism. As a result, slippage in the continuously variable transmission mechanism is avoided. The relationship of the excess amount of the torque capacity is maintained even in the transient state in which the clamping pressure is changed. Therefore, the function as a so-called torque fuse is ensured in which the clutch mechanism precedes the continuously variable transmission mechanism and slips during and after the process of changing the clamping force.

According to a third aspect of the present invention, in the first or second aspect of the invention, when the load or the physical quantity that changes according to the load is equal to or less than a predetermined value, the load on the continuously variable transmission mechanism is reduced. The pinching pressure control device is characterized by further comprising pinching pressure maintaining means for setting a pinching pressure based on the constant value set in advance.

Therefore, in the third aspect of the invention, when the load of the power source or the load acting on the drive system is reduced to a predetermined value or less, the clamping pressure is a value determined with one of those loads as a predetermined constant value. Maintained at. As a result, the absolute value of the clamping force will not be excessively reduced,
It is possible to avoid situations such as slippage of the continuously variable transmission mechanism due to variations in pressure control. In addition, claim 2
When the clutch mechanism described in (1) is provided, it is possible to reduce the torque capacity of the clutch mechanism and improve its release response.

Furthermore, the invention of claim 4 is the same as claim 3
In the invention, in the case where the load or the physical quantity that changes according to the load falls below a predetermined value and the permission condition is not satisfied, a command to set the clamping pressure to a pressure higher than the lower pressure. The clamping pressure control device further comprises means for outputting a clamping pressure command determined by setting the load to the predetermined constant value without outputting.

Therefore, in the invention of claim 4, when the load or the physical quantity is reduced and the permission condition is not satisfied, a command to set the clamping pressure to a relatively high pressure before it is set to the low pressure is issued. Is output, a clamping pressure command determined with the load as a predetermined constant value is output. As a result, the clamping pressure is not increased due to the failure of the permission condition, and the torque capacity of the clutch mechanism according to the second aspect is not increased, and a transient unstable state is avoided.

Furthermore, the invention of claim 5 is the same as claim 1.
In any one of the inventions 1 to 4, the determination that the rotational acceleration of the rotating member exceeds the predetermined value for the rotational acceleration is made in the state where the load of the power source is within the predetermined range. It is a pinching pressure control device characterized by further comprising a judging means for judging by comparison with a value set on the basis of a maximum acceleration that can be caused by a change in a load of a power source.

Therefore, in the fifth aspect of the present invention, when the rotational acceleration occurs due to the fluctuation of the load of the power source while the load of the power source is within the above-mentioned predetermined range, the rotational acceleration changes to the fluctuation of the power source. If the value exceeds the value based on the maximum acceleration within the predetermined range, the permission condition is not satisfied, and if it is less than or equal to the value, the permission condition is satisfied. Therefore, the fluctuation of the load of the power source or the fluctuation of the acceleration associated therewith and the so-called disturbance can be reliably distinguished from each other to the extent that the permission condition is maintained.

According to the invention of claim 6, in the invention of any one of claims 1 to 5, when the clamping pressure is set to a normal pressure higher than the lower pressure because the permitting condition is not satisfied, The clamping pressure control device is characterized by further comprising intermediate pressure setting means for temporarily setting an intermediate pressure higher than the normal pressure.

Therefore, according to the sixth aspect of the present invention, when the clamping pressure is changed from a pressure having a small margin to slip to a normal pressure having a large margin, the permitting condition is no longer satisfied, so that the clamping pressure is higher than the normal pressure. The clamping pressure is once set to the pressure. Therefore, even if the clamping pressure is further increased in order to deal with so-called disturbance, the pressure responsiveness becomes good.

And, the invention of claim 7 is the same as claim 6.
In the invention, when the disturbance that causes the slippage of the torque transmission member is detected within a predetermined time after the clamping pressure is set to the intermediate pressure, the clamping pressure is set to a pressure higher than the intermediate pressure. The clamping pressure control device further includes clamping pressure changing means for increasing the clamping pressure and decreasing the clamping pressure from the intermediate pressure when the disturbance is not detected.

Therefore, in the seventh aspect of the present invention, when so-called disturbance occurs, the clamping pressure is increased to the intermediate pressure, so that the control response for raising the pressure to a higher pressure according to the disturbance becomes good. Further, when no so-called disturbance is detected, the clamping pressure is set to a normal pressure lower than the intermediate pressure, so that the time during which the clamping pressure is high is shortened and the overall power transmission efficiency is reduced. Suppressed.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described based on specific examples. First, a drive system of a vehicle and a control system thereof which are objects of the present invention will be described. FIG. 5 schematically shows a drive system including a belt type continuously variable transmission mechanism 1 as a transmission. The mechanism 1 is connected to a power source 5 via a forward / reverse switching mechanism 2 and a fluid transmission mechanism 4 with a lockup clutch (L / C) 3.

The power source 5 is composed of an internal combustion engine, or an internal combustion engine and an electric motor, or an electric motor,
The point is a drive member that generates power for traveling. In the following description, the power source 5 will be referred to as the engine 5. Further, the fluid transmission mechanism 4 has, for example, a configuration similar to that of a conventional torque converter, and includes a pump impeller rotated by the engine 5, a turbine runner arranged so as to face the pump impeller, and a stator arranged therebetween. The turbine runner is rotated by supplying the spiral flow of the fluid generated by the pump impeller to the turbine runner, and the torque is transmitted.

In the transmission of torque through such a fluid, an unavoidable slip occurs between the pump impeller and the turbine runner, which causes a reduction in power transmission efficiency. Therefore, a member on the input side such as the pump impeller. A lock-up clutch 3 is provided for directly connecting an output side member such as a turbine runner. The lockup clutch 3 is configured to be controlled by hydraulic pressure, and is controlled to be in a completely engaged state, a completely released state, and a slip state which is an intermediate state between these states, and the slip rotation speed thereof is appropriately controlled. You can do it.

The forward / reverse switching mechanism 2 is a mechanism adopted because the rotation direction of the engine 5 is limited to one direction, and outputs the input torque as it is and reverses the output. Is configured to. In the example shown in FIG. 5, a double pinion type planetary gear mechanism is adopted as the forward / reverse switching mechanism 2. That is, the ring gear 7 is arranged concentrically with the sun gear 6, and the pinion gear 8 meshed with the sun gear 6 and the pinion gear 9 meshed with the pinion gear 8 and the ring gear 7 are arranged between the sun gear 6 and the ring gear 7. The pinion gears 8 and 9 are rotatably and revolvably held by the carrier 10. A forward clutch 11 that integrally connects the two rotating elements (specifically, the sun gear 6 and the carrier 10) is provided, and by selectively fixing the ring gear 7, the direction of the output torque is obtained. A reverse brake 12 for reversing is provided.

The continuously variable transmission mechanism 1 has the same structure as a conventionally known belt type continuously variable transmission mechanism, in which a driving pulley 13 and a driven pulley 14 arranged in parallel with each other have a fixed sheave and a fixed sheave, respectively. Hydraulic actuators 15 and 16
And a movable sheave that can be moved back and forth in the axial direction. Therefore, the groove width of each pulley 13, 14 changes by moving the movable sheave in the axial direction, and accordingly, the winding radius of the belt 17 wound around each pulley 13, 14 (the effective diameter of the pulleys 13, 14). ) Changes continuously, and the gear ratio changes continuously. The drive pulley 13 is connected to the carrier 10, which is an output element of the forward / reverse switching mechanism 2.

The hydraulic actuator 16 in the driven pulley 14 receives hydraulic pressure (line pressure or its correction pressure) corresponding to the torque input to the continuously variable transmission mechanism 1 via a hydraulic pump and hydraulic control device (not shown). Is being supplied. Therefore, each sheave in the driven pulley 14 sandwiches the belt 17 so that tension is applied to the belt 17 and a clamping pressure (contact pressure) between the pulleys 13 and 14 and the belt 17 is secured. . On the other hand, the hydraulic actuator 1 in the drive pulley 13
5, the pressure oil corresponding to the gear ratio to be set is supplied,
The groove width (effective diameter) is set according to the target gear ratio.

The driven pulley 14 is connected to a differential 19 via a gear pair 18, and torque is output from the differential 19 to the drive wheels 20. Therefore, in the above drive system, the lockup clutch 3 corresponding to the clutch of the present invention and the continuously variable transmission mechanism 1 are arranged in series between the engine 5 and the drive wheels 20.

Various sensors are provided to detect the operating state (running state) of a vehicle equipped with the continuously variable transmission 1 and the engine 5. That is, a turbine rotation speed sensor 21 that detects the input rotation speed (rotation speed of the turbine runner) to the continuously variable transmission 1 and outputs a signal, and an input rotation speed that detects the rotation speed of the drive pulley 13 and outputs a signal. A sensor 22, an output rotation speed sensor 23 that detects the rotation speed of the driven pulley 14 and outputs a signal, and a wheel speed sensor 24 that detects the rotation speed of the drive wheel 20 and outputs a signal are provided. Further, although not particularly shown, an accelerator opening sensor that detects a depression amount of the accelerator pedal and outputs a signal, a throttle opening sensor that detects a throttle valve opening and outputs a signal, and a brake pedal are depressed. A brake sensor that outputs a signal in some cases is provided.

Control of engagement / release of the forward clutch 11 and the reverse brake 12 and the belt 17
An electronic control unit (CVT-ECU) 25 for a transmission is provided to control the clamping pressure of the gear, the gear ratio, and the lockup clutch 3. The electronic control unit 25 is mainly composed of a microcomputer as an example, performs an operation in accordance with a predetermined program based on input data and previously stored data, and performs various states such as forward and reverse or neutral. The required clamping force setting, the gear ratio setting, the engagement / disengagement of the lockup clutch 3, and the slip rotation speed are controlled.

Here, examples of data (signals) input to the transmission electronic control unit 25 are shown as a signal of the input speed Nin of the continuously variable transmission 1 and an output speed of the continuously variable transmission 1. A No signal is input from the corresponding sensor (not shown). Further, from an engine electronic control unit (E / G-ECU) 26 that controls the engine 5, an engine speed Ne signal, an engine (E / G) load signal, a throttle opening signal, an accelerator pedal (not shown). The accelerator opening signal, which is the amount of depression, is input.

According to the continuously variable transmission mechanism 1, since the engine speed, which is the input speed, can be controlled steplessly (in other words, continuously), the fuel consumption of the vehicle equipped with the engine speed can be improved. For example, the target drive force is obtained based on the required drive amount represented by the accelerator opening degree and the vehicle speed, and the target output required to obtain the target drive force is obtained based on the target drive force and the vehicle speed. The engine speed for obtaining the target output with the optimum fuel economy is obtained based on a map prepared in advance, and the gear ratio is controlled so as to become the engine speed.

In order not to impair such an advantage of improving fuel economy, the power transmission efficiency of the continuously variable transmission 1 is controlled to a good state. Specifically, the torque capacity of the continuously variable transmission 1, that is, the belt clamping pressure, is a belt clamping pressure that is as low as possible within a range in which the target torque determined based on the engine torque can be transmitted and the belt 17 does not slip. Controlled.

On the other hand, when the torque applied to the drive system including the continuously variable transmission mechanism 1 suddenly changes due to sudden braking, rapid acceleration, riding on a falling object, a step, etc.,
There is a high possibility that the torque capacity of the continuously variable transmission mechanism 1 is relatively insufficient and the belt 17 slips. As described above, when the continuously variable transmission 1 slips and is partially worn, this may damage the continuously variable transmission 1.
Therefore, the control device of the present invention executes the control for reducing the clamping pressure only in the specific traveling state.

Here, the control for reducing the clamping pressure is a pressure lower than the clamping pressure normally set with a certain safety factor (safety factor is based on the running state at that time or the driving state of the drive system). It is a control to reduce the pressure). In other words, the control is performed so that the excess amount or the margin amount of the clamping pressure with respect to the minimum clamping pressure in the range where the slip does not occur is smaller than the normal time.

FIG. 1 is a flow chart showing an example of the pinching control carried out by the control device of the present invention. In the example shown here, first, the traveling state of a vehicle equipped with the drive system including the continuously variable transmission 1 is determined, and it is determined whether the traveling state is within a predetermined region I or not. (Step S1). This region is a region where the engine load (or engine torque or input torque of the continuously variable transmission 1) is set for each vehicle speed, and an example thereof is schematically shown in FIG.

The area map shown in FIG. 2 is a map in which the vertical axis represents engine load (throttle opening or accelerator opening or input torque of the continuously variable transmission 1) and the horizontal axis represents vehicle speed. Region I is a predetermined width centered on the road for a zero flat road. For example, it is a region surrounded by a line showing a torque of several percent above and below the load line. The area outside this area is
Area II. Therefore, this region II is
2 exists on the upper side (high load side) and the lower side (low load side) of FIG. Then, a region where the accelerator opening degree is equal to or less than a predetermined low load and is equal to or less than 0 is set as a region III. Area above
While I changes to the high load side according to the vehicle speed, this region III is a constant region that does not change with vehicle speed.

Therefore, in step S1, the engine load (input torque Tin) at that time is the lower limit load of the region I at the vehicle speed at that time (lower limit input torque TinL).
It is judged whether or not it is within the range between the upper limit load and the upper limit load (upper limit input torque TinU). Area of vehicle running
If the answer is YES in step S1 due to the fact that the vehicle is in I, it is determined whether or not the vehicle is in a steady running state (step S2).

The steady running state is basically a state in which the behavior of the vehicle and the driving state are little changed. This can be determined based on acceleration, load, change in gear ratio, or the like. As an example, the rotational acceleration of any of the rotating members constituting the drive system such as the output shaft of the continuously variable transmission 1 is less than or equal to a predetermined value and / or the gear ratio γ of the continuously variable transmission 1 is When the rate of change is less than or equal to a predetermined value, and further, the rate of change in accelerator opening is less than or equal to a predetermined value, it can be determined that the vehicle is in a steady running state.

In the drive system shown in FIG. 5, the rotational acceleration of the output shaft of the continuously variable transmission mechanism 1 is determined. However, if the configuration of the drive system is different, the rotational acceleration of other rotating members may be determined. Is preferred. For example, the continuously variable transmission mechanism 1
When a clutch is provided on the downstream side of, the rotational acceleration on the output side of the clutch is preferably obtained, and the steady traveling state is determined based on the rotational acceleration. That is, it is preferable to obtain the rotational acceleration of the drive wheels (drive system) from the output shaft of the drive train in which the continuously variable transmission mechanism 1 and the clutch are connected in series, and determine the steady running state based on the rotational acceleration.

Since the vehicle is in a steady running state, step S
When the determination is affirmative in step 2, a command is output to set the pressure of the lockup clutch 3 in the above-mentioned region I of the hydraulic pressure (engagement pressure) to a predetermined pressure (step S3).
Specifically, a command to reduce the engagement pressure is output. This is a control for reducing the excess amount of the engagement pressure with respect to the lowest engagement pressure (in other words, the margin of the engagement pressure) within the range where the lock-up clutch 3 does not slip.

Then, it is determined whether or not the elapsed time from the output of the command has reached a predetermined time set in advance (step S4). The predetermined time is set as the time required for the engagement pressure of the lockup clutch 3 to actually decrease to the command pressure from the command to reduce the engagement pressure of the lockup clutch 3. Therefore, if a negative determination is made in step S4, the control returns and the control is continued. If a negative determination is made in step S1 or step S2 during this predetermined time, control proceeds to step S6 and subsequent steps, which will be described later.

On the other hand, if the affirmative determination is made in step S4, the clamping pressure of the continuously variable transmission 1 is set to the above range.
A command for setting a preset pressure to I is output (step S5). Specifically, a command to reduce the clamping pressure is output. This is a control for reducing the excess amount of the clamping pressure (in other words, the margin of the clamping pressure) with respect to the minimum clamping pressure within the range where the belt 17 which is the torque transmission member of the continuously variable transmission 1 does not slip.

That is, step S1 and step S2
If the affirmative determination is made in step 1, the permitting condition is satisfied, and as a result, the clamping pressure is set to a pressure lower than the pressure in the normal state in which the above permitting condition is not satisfied. This is a control based on the judgment that the behavior or driving state of the vehicle is stable, and as a result, the clamping pressure is reduced without causing the belt 17 to slip, and the power of the continuously variable transmission mechanism 1 is reduced. Transmission efficiency is improved, which in turn improves the fuel efficiency of the vehicle.

When the clamping pressure is reduced as described above, the engagement pressure (that is, the torque capacity) of the lock-up clutch 3 is reduced prior to that, and then the clamping pressure is reduced. Therefore, the so-called margin or the margin of torque capacity for slippage is determined by the continuously variable transmission 1
On the other hand, the lockup clutch 3 becomes low (in other words, the transmission torque of the lockup clutch 3 becomes smaller than the transmission torque of the continuously variable transmission 1), and that state is maintained even in the transient state in which the clamping pressure is reduced. It Therefore, even if the torque applied to the drive system temporarily increases due to some reason, the lock-up clutch 3 slips prior to the continuously variable transmission mechanism 1. Therefore, excessive slippage in the continuously variable transmission mechanism 1 occurs. And damage caused by it are avoided in advance. The so-called torque fuse function of the lockup clutch 3 is ensured.

The above step S1 or step S2
If the determination is negative in step S6, it is determined whether the running state or driving state of the vehicle is within the area II shown in FIG. 2 (step S6). In the region II, as shown in FIG. 2, the input torque Tin is the upper limit value Tin that defines the region I.
Since both the region exceeding U and the region falling below the lower limit value TinL are both affirmatively determined in step S6, is the driving state of the vehicle within the lower region of the region II? It is determined whether or not, that is, whether the engine load or the input torque is much lower than the road load (step S7).

If the determination in step S7 is affirmative, it is determined whether the input torque continues to decrease and the speed of decrease is high (whether the speed of decrease is equal to or greater than a predetermined value). (Step S8). When a negative determination is made in step S8, and when a negative determination is made in step S7, a command for setting a predetermined clamping pressure for region II is output (step S9). Specifically, a command to increase the clamping pressure is output. This is a control for increasing the amount of excess clamping pressure (in other words, the margin of clamping pressure) with respect to the minimum clamping pressure within the range where the continuously variable transmission 1 does not slip. As an example, the line pressure, which is the source pressure of the hydraulic pressure that controls the continuously variable transmission mechanism 1, is increased to about the clamping pressure.

Then, it is judged whether or not the elapsed time from the output of the command reaches a predetermined time set in advance (step S10). The predetermined time is set as the time required for the actual clamping pressure to drop to the command pressure from the clamping pressure reduction command. Therefore, if the determination in step S10 is negative, the control is returned and the control is continued. If the affirmative determination is made in step S1 or step S2 described above during the predetermined time, the control proceeds to step S3 and thereafter, and step S3.
If the determination is negative in 6 or affirmative in step S8, the process proceeds to step S12 described below.

On the other hand, if the affirmative determination is made in step S10, a command for setting the engagement pressure of the lockup clutch 3 to a predetermined pressure for the above-mentioned region II is output (step S11). . Specifically, a command to increase the engagement pressure of the lockup clutch 3 is output.
The engagement pressure of the lockup clutch 3 that is set as a result is an engagement pressure at which the margin for sliding is smaller than the margin for the clamping pressure in the continuously variable transmission 1. This is because the lockup clutch 3 functions as a so-called torque fuse for the continuously variable transmission 1.

When the clamping pressure is increased as described above, the clamping pressure is increased before the engagement pressure of the lockup clutch 3 is increased, and then the engagement pressure of the lockup clutch 3 is increased. Therefore, the so-called margin width or the margin amount of the torque capacity for slippage becomes low in the lockup clutch 3 with respect to the continuously variable transmission mechanism 1, and that state is maintained even in the transient state in which the clamping pressure is reduced. for that reason,
Even if the torque applied to the drive system temporarily increases due to some reason, the lock-up clutch 3 slips prior to the continuously variable transmission mechanism 1. Therefore, excessive slippage in the continuously variable transmission mechanism 1 and The resulting damage is avoided in advance. The so-called torque fuse function of the lockup clutch 3 is ensured.

If a negative determination is made in step S6, that is, if the vehicle running state at that time is neither in the region I nor in the region II, a certain load against a predetermined load in the region III is detected. The pressure is commanded (step S12). That is, in the regions I and II, the clamping pressure is controlled so that the excess amount (the clamping pressure margin width) with respect to the clamping pressure at which slippage occurs in the continuously variable transmission 1 becomes a predetermined amount. The value becomes a value according to the engine load or the input torque, and changes to high or low as the engine load or the input torque increases or decreases.

If such control is maintained, for example, even when the accelerator pedal is completely returned and the accelerator opening is almost zero (accelerator fully closed), the clamping pressure is controlled to a considerably low pressure. Along with this, the influence of unavoidable variations in the clamping pressure control relatively increases, and even if the clamping pressure is temporary, it becomes too small and slippage may occur in the continuously variable transmission mechanism 1. Therefore, in region III, in order to avoid such an inconvenience, the clamping pressure is set to a value for a constant input torque regardless of the engine load or the input torque. Therefore its value is region I
The pressure is higher than the pressure set on the basis of the engine load or the input torque in accordance with the control described in 1. In other words, in the state where the engine load or the input torque is equal to or less than the predetermined value, the control in the region III is executed prior to the control in the region I.

On the other hand, while the clamping pressure of the continuously variable transmission 1 is set to a constant pressure, a command for reducing the engagement pressure (torque capacity) of the lockup clutch 3 is output (step S13). That is, the margin of the engagement pressure (torque capacity) with respect to slippage in the lockup clutch 3 is reduced. If the engine load is reduced and sudden braking is performed in this state, for example, the lockup clutch 3 is immediately released.
This is to prevent the engine speed from being significantly reduced and the engine stall to be accompanied by the reduction of the engine speed.

The control in steps S12 and S13 is executed even when the engine load or the input torque is reduced from the steady running state in the region I. For example, when the steady traveling state indicated by P1 point in FIG. 2 is changed to the traveling state indicated by P2 point, the clamping pressure in the continuously variable transmission mechanism 1 is immediately set to a value for a constant input torque,
Further, the engagement pressure (torque capacity) of the lockup clutch 3 is reduced. In that case, the traveling state of the vehicle changes after passing through the region II. However, as the control of the clamping pressure and the engagement pressure of the lockup clutch 3, the control for the region II is not executed but the region immediately. Control for III is performed.

As a result, complicated control such as transiently increasing the clamping pressure or the engaging pressure and then lowering these pressures is avoided. In addition, the control response is improved accordingly. In addition, transient instability is reduced, so
Control reliability is improved.

As described above, the control device of the present invention changes the clamping pressure of the continuously variable transmission mechanism 1 to high or low according to the running state of the vehicle. An example of control for changing the clamping force is shown in FIG.
Will be described with reference to.

First, the flag F indicating the set clamping pressure level is judged (step S21). As will be described below, in the control shown here, the clamping pressure is changed in four stages of low level, normal level, intermediate level, and high level, so that level is indicated by the set value of the flag F. The flag F is set to "1" at a low level clamping pressure, "0" at a normal level, "3" at an intermediate level, and "4" at a high level.

When it is determined in step S21 that the flag F is set to "0" or "1", it is determined whether the running state or the driving state of the vehicle is within the area I shown in FIG. It is determined whether or not (step S22). This is the same judgment as the judgment in step S1 shown in FIG.

If an affirmative determination is made in step S22, first, it is determined whether or not the rotational acceleration of the rotary member forming the drive system is equal to or greater than a reference value as a determination as to whether or not the vehicle is in a steady running state. (Step S23). Specifically, it is determined whether or not the absolute value of the change rate ΔNo of the output shaft rotation speed No is equal to or greater than the reference value ΔNo1. This reference value ΔNo1
Is a value set based on the maximum acceleration when the engine load or the input torque changes in the above-mentioned region I, and more specifically, is a value substantially equal to the maximum acceleration. By setting the reference value ΔNo1 in this way,
The steady running state and the unsteady running state can be reliably distinguished.

At the same time, it is determined whether or not the absolute value of the rate of change (or amount of change) Δγ of the gear ratio γ is greater than or equal to a predetermined reference value Δγ1 (step S23). If the rotational acceleration ΔNo and the gear ratio change rate Δγ are smaller than the respective reference values, it can be determined that the vehicle is in a steady running state. Therefore, in these steps S22 and S23, it is determined that the precondition for controlling the clamping pressure to be low (that is, the permission condition of the present invention) is satisfied.

If a negative determination is made in step S23, the permission condition is satisfied, so an instruction to set the clamping pressure to a low level is output (step S2).
4). This low-level clamping pressure is the clamping pressure predetermined for the region I indicated in step S5 of FIG. 1 described above. Then, the flag F is set to "1" (step S25) to indicate that the clamping pressure is set to the low level, and then the process returns.

On the other hand, if the engine is not in the steady running state even if the engine load or the input torque is in the region I, that is, if the determination in step S23 is affirmative, the flag F is "1" or "0". Is determined (step S26). When the flag F is set to "1", the traveling condition is changed to the unsteady state in the condition that the permitting condition is satisfied and the clamping pressure is set to the low level (the clamping pressure in the region I). It will be.

Since this is a state in which the torque acting on the drive system changes and slippage is likely to occur in the continuously variable transmission mechanism 1, an intermediate level pressure is indicated as the clamping pressure (step S27). This intermediate level clamping pressure is a pressure between the normal level and the high level, and thus can be said to be in a state of being prepared for switching to the normal level and the high level. Then, the flag F is set to "3" to indicate that the clamping pressure is set to the intermediate level (step S28).

The slip of the tire (driving wheel) is determined with the clamping pressure set to the intermediate level (step S2).
9). Specifically, it is determined whether or not the absolute value of the change rate ΔNo of the output shaft rotation speed No is equal to or greater than a predetermined reference value ΔNo2.
This reference value ΔNo2 is a value larger than the reference value ΔNo1 in step S23 described above, and by doing so, it is possible to prevent erroneous determination under a wide range of driving conditions including the influence of the state of the road surface.

As a factor of the change from the steady running state to the non-steady running state, a change in the driving state due to an accelerator operation or the like and disturbance may be considered, and such a factor is determined in step S29. Therefore, when step S29 is negatively determined because the tire slip is not detected, it is determined whether or not a predetermined time period has elapsed (step S30).

That is, elapse of a predetermined time (step S30
It is confirmed that the tires do not slip, after which the instruction to set the clamping pressure to the normal level pressure is output (step S31). This normal level clamping pressure is a predetermined pressure for the area II shown in FIG. 2 described above. Then, the flag F is set to "0" to indicate that the clamping pressure is set to the normal level (step S32), and then the process returns.

As described above, in the control shown in FIG. 3, the time for maintaining the clamping pressure at the intermediate level is limited to the above-mentioned predetermined time, and if the tire does not slip, the clamping pressure is reduced to the normal level. As a result, the time for maintaining the clamping pressure at an intermediate level that is somewhat high is short, so it is possible to prevent or suppress the reduction in power transmission efficiency and the deterioration in fuel consumption due to the high clamping pressure.

Incidentally, since the elapsed time after the flag F is set to "3" in the above step S28 does not reach the predetermined time, a negative determination is made in step S30, and when the return is made, "F =" in step S21 mentioned above. The 3 "judgment is established. In that case, since the determination about the flag F in step 33 has the same determination result, the process proceeds to step S29 again, and the slip of the tire is detected.

If the determination in step S29 is affirmative, it means that tire slip has been detected while the clamping pressure is maintained at the intermediate level. In this case, an instruction to set the clamping pressure to the high level is given. Is output (step S3
5). This is, for example, the clamping pressure set by the hydraulic pressure corresponding to the line pressure that is the original pressure of the control hydraulic pressure of the continuously variable transmission mechanism 1. Therefore, this high-level clamping pressure is set by increasing the pressure from the intermediate level, which is already high to some extent, so that it is set without delay and its control response becomes good.

Then, the flag F is set to "4" to indicate that the clamping pressure is set to the normal level (step S
36) and then it is determined whether or not the tire slip has converged (step S37). Here, convergence of tire slip means that the drive wheels slip and the output shaft acceleration increases,
After that, the drive wheel recovers the grip force, and accordingly, the change in the rotation speed of the rotating member and the inertial force of the rotating member constituting the drive system are within a predetermined value. It can be determined based on the acceleration. In addition, the specific method of the determination can be appropriately selected.

Therefore, if the determination of step S37 is negative because the convergence of slippage is not detected,
The process returns to maintain the clamping pressure at a high level, and conversely, when the slip convergence is detected, the flag F is set to "0" (step S38). After that, the clamping pressure control is executed according to the traveling state of the vehicle. When the return is negative in step S37, the process proceeds to step S33 because the determination of "F = 4" is established in step S21 described above. Further, since the determination of "F = 4" is established in step S33, tire slip is determined again in step S37.

On the other hand, if the traveling state of the vehicle is in the above-mentioned region I but the traveling state is unsteady and the clamping pressure at that time is the normal level, "F = 0" in step S26 described above. The judgment of "is established. In that case,
Since the clamping pressure has already been raised to the normal level, the slip of the tire (driving wheel) is determined (step S3).
9). Specifically, it is determined whether or not the absolute value of the change rate ΔNo of the output shaft rotation speed No is equal to or greater than a predetermined reference value ΔNo2.
This is similar to the determination in step S29 described above.

If a negative determination is made in step S39 because no tire slip has been detected, an instruction to set the clamping pressure to the normal level pressure is output (step S40). This normal level clamping pressure is a predetermined pressure for the area II shown in FIG. 2 described above. Then, the flag F is set to "0" to indicate that the clamping pressure is set to the normal level (step S38), and then the process returns.

On the other hand, if a positive determination is made in step S39 because the tire slip has been detected, the process proceeds to step S35 described above, and an instruction to set the clamping pressure to a high level is output. The same control as described above is performed.

It should be noted that since the running state or the driving state of the vehicle is not within the above-mentioned region I, step S2
If the determination is negative in step 2, immediately step S3
Proceed to step 9 to determine tire slip. That is, the traveling state determined to be negative in step S22 is a traveling state far from the road load, and is a state in which a relatively large safety factor should be set for controlling the clamping pressure. Therefore, in this case, the normal level of clamping pressure is set, and if a disturbance such as tire slippage is detected in the process, the clamping pressure is further increased.

Road FIG. 4 is a time chart showing an example of changes in the clamping pressure when the above control is carried out while the vehicle is traveling steadily near the road. In this case, the clamping pressure is set to the low level described above, and in that state the output shaft rotation speed No increases (time A), and when the rate of change ΔNo becomes equal to or greater than the reference value ΔNo1 described above (time B), The clamping pressure is raised to an intermediate level. When such a change in the output shaft rotational speed No is caused by tire slippage, the rate of change ΔNo rises above the second reference value ΔNo2 (C
Point in time), and therefore, the slip of the tire is determined and the clamping pressure is increased to a high level. After that, when the rate of change ΔNo of the output shaft speed No becomes equal to or greater than the third reference value ΔNo3 (at the time point D), the control for reducing the engine torque Te is executed. This is done, for example, by retarding the ignition timing.

Next, after the output shaft speed No. has been increased to the maximum (at the time point E), the slippage of the tire is eliminated and the speed is gradually decreased. Then, when the number of revolutions becomes substantially equal to the gear ratio, the determination of convergence of tire slip is established (time F). After that, the clamping pressure is controlled to a level according to the running state of the vehicle.

If tire slippage is not detected within a predetermined time T from time B when the determination of the unsteady state is established, the clamping pressure is returned to the normal level when the predetermined time T elapses. . This is indicated by a thin solid line in FIG.

Further, in FIG. 4, changes in the clamping pressure due to control when the clamping pressure is not set to a low level or an intermediate level are shown by broken lines. That is, in this case, the output shaft speed N
When the change rate ΔNo of o becomes equal to or larger than the third reference value ΔNo3, the clamping pressure is increased from the normal level to the high level, and at the same time, the engine torque reduction control is executed. Therefore, slippage may occur in the continuously variable transmission mechanism 1 due to an unavoidable delay when increasing the clamping pressure. Further, since the clamping pressure is set to be relatively high in the steady traveling state prior to that, power transmission efficiency may be reduced and fuel efficiency may be deteriorated.

The relationship between the above-described specific example and the present invention will be briefly described below. Steps S1 and S2 shown in FIG. 1, steps S22 and S23 shown in FIG.
The functional means of is equivalent to the means of permitting and prohibiting in the invention of claim 1. Further, the functional means of step S3 and step S5, step S9 and step S11 correspond to the pressure adjusting means in the invention of claim 2. Further, the functional means of step S12 corresponds to the clamping pressure maintaining means in the invention of claim 3. The functional means for executing the control of step S12 after a negative determination is made in steps S1, S2, S6 shown in FIG. 1 corresponds to the means for outputting the command in the invention of claim 4.

On the other hand, the functional means of step S23 shown in FIG. 2 corresponds to the judging means in the invention of claim 5.
Further, the functional means of step S27 corresponds to the intermediate pressure setting means in the invention of claim 6. Further, the functional means for executing step S31 or step S35 after setting the intermediate level in step S27 corresponds to the clamping pressure changing means in the invention of claim 7.

The present invention is not limited to the above specific examples, and various modifications can be made. For example, instead of the engine load or the input torque, the driven pulley 14
The torque on the rotating shaft of may be adopted. Alternatively, when a fluid coupling such as a torque converter is provided on the front side of the continuously variable transmission 1, the torque of the output member of the fluid coupling (for example, turbine torque) may be used as the input torque. Alternatively, belt torque may be adopted. Further, instead of the determination that the engine load or the input torque is within the predetermined range, it may be determined that the ratio of the input rotation speed to the output rotation speed in the continuously variable transmission 1 is within the predetermined range. Therefore, the "physical quantity" in the present invention is not limited to the torque, but includes a detectable quantity such as the rotation speed and its change rate.

On the other hand, in order to judge the steady running state, the rate of change of the output shaft rotational speed, that is, the rotational acceleration of the output shaft is replaced with the rotational acceleration of the rotating member on the output side or one of the rotating members constituting the drive system. The steady state may be determined based on the rotational acceleration. Further, the determination of the steady state may include the rate of change or the rate of change of the gear ratio, but this is not essential and may be appropriately adopted.

Further, although the belt type continuously variable transmission mechanism has been described as an example in the above specific example, the continuously variable transmission mechanism of the present invention may be a traction type and the clutch mechanism may be a lock mechanism. The clutch is not limited to the up clutch, and may be any clutch that is arranged in series with the continuously variable transmission mechanism in the torque transmission direction.

[0086]

As described above, according to the invention of claim 1, the load of the power source or the physical quantity corresponding thereto is within the predetermined range, and the rotational acceleration of any one of the rotating members is within the predetermined range. In this case, since the clamping pressure is reduced, the clamping pressure is reduced or does not decrease in response to various running states of the vehicle, so slippage in the continuously variable transmission can be reliably prevented, and at the same time, the clamping pressure can be reduced. It is possible to reduce the fuel consumption to improve fuel efficiency.

According to the second aspect of the present invention, when the clamping pressure for slipping or the margin of engagement pressure is set larger in the continuously variable transmission than in the clutch mechanism and the clamping pressure is changed, the margin is changed. The magnitude relationship of the amount can be maintained even in the transient state of changing the clamping pressure.Therefore, the clutch mechanism reliably functions as a so-called torque fuse for the continuously variable transmission mechanism during the process of changing the clamping pressure and thereafter, and continuously variable transmission. It is possible to reliably prevent the mechanism from slipping.

Further, according to the third aspect of the invention, since the absolute value of the clamping pressure is not excessively reduced, the situation such as slippage of the continuously variable transmission mechanism due to variations in pressure control or the like can be prevented. This can be avoided, and in the case where a clutch mechanism is provided, the torque capacity of the clutch mechanism can be reduced to improve its release response.

Further, according to the invention of claim 4, when the clamping pressure is reduced to a value for a predetermined constant load, the clamping pressure is once increased in the process, and the engagement pressure of the clutch mechanism is accordingly increased. It is possible to avoid complicated control such as raising the temperature, and also to avoid transient instability and improve control reliability.

According to the invention of claim 5, when the load of the power source is within the above-mentioned predetermined range and the rotational acceleration occurs due to the change of the load of the power source, the rotational acceleration is If the value exceeds the value based on the maximum acceleration in the predetermined range due to the fluctuation of the source, the permission condition is not satisfied, and if it is less than that value, the permission condition is satisfied, It is possible to reliably distinguish the so-called disturbance from the fluctuation of the load of the power source or the fluctuation of the acceleration accompanying it to the extent that the establishment of the permission condition is maintained.

According to the sixth aspect of the present invention, when the clamping pressure is changed from a pressure with a small margin to slip to a normal pressure with a large margin, the permission condition is no longer satisfied. Since the clamping pressure is once set to a pressure higher than the pressure, even if the clamping pressure is further increased to cope with so-called disturbance, the pressure response can be improved.

Further, according to the invention of claim 7, when so-called disturbance occurs, the clamping pressure is raised to the intermediate pressure, so that the control responsiveness for raising the pressure to a higher pressure according to the disturbance is obtained. In addition, when the so-called disturbance is not detected, the clamping pressure is set to a normal pressure that is lower than the intermediate pressure, so the time during which the clamping pressure is high is shortened and the power transmission as a whole is reduced. It is possible to suppress a decrease in efficiency and, in turn, improve fuel efficiency of the vehicle.

[Brief description of drawings]

FIG. 1 is a diagram showing a flowchart for explaining an example of control by a control device of the present invention.

FIG. 2 is a diagram showing an example of regions divided to set a traveling state of a vehicle with different clamping pressures.

FIG. 3 is a diagram showing a flowchart for explaining another example of control by the control device of the present invention.

FIG. 4 is a diagram schematically showing a change in clamping pressure when the control shown in FIG. 3 is executed.

FIG. 5 is a diagram schematically showing a drive system and a control system of a vehicle equipped with a continuously variable transmission mechanism according to the present invention.

[Explanation of symbols]

1 ... Continuously variable transmission mechanism, 3 ... Lock-up clutch, 5
... Engine (power source), 13 ... Drive pulley, 14 ...
Driven pulleys, 15, 16 ... Actuator, 17 ... Belt, 20 ... Driving wheel, 25 ... Electronic control unit for transmission (CVT-ECU).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16H 59:48 F16H 59:48 63:06 63:06 (72) Inventor Kazumi Hoshiya Toyota City, Aichi Prefecture Toyota Town No. 1 Toyota Motor Co., Ltd. (72) Inventor Yasuhiro Okukai Toyota Town, Aichi Prefecture Toyota City No. 1 Toyota Motor Co., Ltd. F Term (reference) 3J053 CA03 CB15 CB21 CB25 DA01 DA02 DA04 DA06 DA07 DA26 3J552 MA07 MA09 MA12 NA01 NB01 PA12 PA59 RA02 SA36 TB11 UA02 VA14W VA18W VA32Z VA37Z VA39W VA39Y VA52W VB01Z VC02W VC03Z VD02Z VD11Z

Claims (7)

[Claims] 1. The clamping pressure of a continuously variable transmission mechanism in which the torque capacity changes according to the clamping pressure that clamps the torque transmitting member is lower than a predetermined pressure within a range in which the torque transmitting member does not slip. In a clamping pressure control device for a continuously variable transmission that reduces pressure, a load of a power source of a vehicle in which the continuously variable transmission is mounted or any rotation that constitutes a drive system including the continuously variable transmission. A permission condition is satisfied in which the physical quantity of the member that changes according to the load is within a predetermined range and the rotational acceleration of any of the rotating members that make up the drive system is within a predetermined range. If you do
Allowing the clamping pressure to be reduced to the lower pressure,
A clamping pressure control device for a continuously variable transmission, comprising means for prohibiting the clamping pressure from decreasing to the low pressure when the permission condition is not satisfied. 2. A torque capacity excess smaller than a torque capacity excess quantity with respect to a torque capacity in which the torque transmission member in the continuously variable transmission mechanism is slipped and connected in series to the continuously variable transmission mechanism in a torque transmission direction. A clutch mechanism set to an amount, when the permitting condition is no longer satisfied and the clamping pressure is increased from the low pressure, and when the permitting condition is satisfied, the clamping pressure is reduced to the low pressure, The pressure adjusting means for changing the clamping pressure and the torque capacity of the clutch mechanism while maintaining the magnitude relation of the torque capacity excess amount in the transitional state of the clamping pressure change is further provided. A clamping force control device for a continuously variable transmission according to item 1. 3. When the load or a physical quantity that changes according to the load is equal to or less than a predetermined value, a load for the continuously variable transmission is set to a predetermined constant value, and the load is set based on the constant value. The clamping pressure control device for a continuously variable transmission according to claim 1 or 2, further comprising clamping pressure maintaining means for determining the pressure. 4. The clamping pressure is set to a pressure higher than the lower pressure when the load or a physical quantity that changes according to the load falls below a predetermined value and the permission condition is not satisfied. 4. A means for outputting a clamping pressure command determined with the load as the predetermined constant value without outputting a command, further comprising means.
A clamping force control device for a continuously variable transmission according to item 1. 5. The load of the power source is determined in a state where the load of the power source is within the predetermined range determined in advance by determining that the rotational acceleration of the rotating member exceeds the predetermined value of the rotational acceleration. 5. The clamping force of the continuously variable transmission mechanism according to claim 1, further comprising a judging means for judging by comparison with a value set based on a maximum acceleration that can be caused by a change in Control device. 6. An intermediate pressure setting means for temporarily setting an intermediate pressure higher than the normal pressure when the clamping pressure is set to the normal pressure higher than the low pressure because the permission condition is not satisfied. The clamping pressure control device for a continuously variable transmission according to any one of claims 1 to 5, wherein: 7. The clamping pressure is higher than the intermediate pressure when a disturbance that causes slippage of the torque transmission member is detected within a predetermined time after the clamping pressure is set to the intermediate pressure. 7. A clamping pressure control device for a continuously variable transmission mechanism according to claim 6, further comprising clamping pressure changing means for increasing the clamping pressure to lower the intermediate pressure when the disturbance is not detected. .