JP2005351334A - Controller of continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the responsiveness of a holding pressure after recovering an improper pressure regulation in a continuously variable transmission. <P>SOLUTION: In this controller of a continuously variable transmission, based on a deviation between a target value and an actual value, operating conditions are set by a hydraulic pressure regulated by a feedback control including integrated operations. The controller comprises an improper pressure regulation detection means for detecting that the pressure regulation of the hydraulic pressure is not proper (step S104) and a limiting means for limiting an increase in the value of an integration item in the integrated operation while the improper pressure regulation is detected by the improper pressure regulation detection means (step S207). While the improper pressure regulation is detected, the increase in the value of the integration item in the integrated operation is limited. Accordingly, since the increase in the integrated item in a so-called abnormal state is absent, the integration item in a so-called stationary state recovered from the improper pressure regulation is not increased excessively. As a result, the responsiveness of the hydraulic pressure after the improper pressure regulation of the hydraulic pressure is recovered can be increased. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a continuously variable transmission whose operating state is changed by hydraulic pressure.

  The belt-type continuously variable transmission and the traction-type continuously variable transmission transmit torque using the frictional force between the belt and the pulley and the shearing force of the traction oil between the disk and the roller. Therefore, the torque capacity of these continuously variable transmissions is a capacity according to the pressure acting on the location where the torque is transmitted.

  The above-mentioned pressure in a continuously variable transmission is referred to as pinching pressure. Increasing the pinching pressure can increase the torque capacity and avoid slipping, but on the other hand, more power than necessary to generate high pressure. There are inconveniences such as consumption or reduction in power transmission efficiency. For this reason, generally, the clamping pressure is set as low as possible by controlling the line pressure of the hydraulic circuit within a range in which unintended slip does not occur.

  For example, in a vehicle equipped with a continuously variable transmission, the engine speed can be controlled by the continuously variable transmission to improve fuel efficiency. In order to improve the transmission efficiency as much as possible, by controlling the line pressure of the hydraulic circuit, the clamping pressure is controlled to be set as low as possible without causing slippage. PID control is an example of the operation. It is feedback controlled by such as.

However, there may be a case where control cannot be performed so as to maintain a preset minimum hydraulic pressure due to variations in hydraulic circuits in individual products and variations in operation characteristics. For this reason, in Patent Document 1, when the responsiveness when the line pressure decreases, such as when the actual hydraulic pressure of the line pressure drops only to P1, the level slightly lower than P1 with respect to the minimum value P0 of the target hydraulic pressure is set. An invention configured to set a threshold value, and to fix the integral value (I term) at that time when the target hydraulic pressure of the line pressure is equal to or lower than the threshold value, and to perform integral correction based on the fixed integral value Is described.
JP 2001-263470 A

  According to the invention of Patent Document 1, it is possible to avoid an increase in the integrated value and to accumulate it, and to obtain good responsiveness even when the actual hydraulic pressure of the line pressure does not fall to the target hydraulic pressure.

  However, the invention of Patent Document 1 is for performing control when the hydraulic pressure is sufficiently generated and cannot be reduced to the target pressure. Therefore, the so-called original pressure by an oil pump or the like is sufficient. It cannot be used for control in a state where it does not occur. For example, when the engine speed decreases rapidly, such as when the vehicle suddenly stops, and the pumping amount of the oil pump driven by the engine decreases, target oil pressure such as line pressure is generated by the oil pump. When the pressure is higher than the pressure to be obtained, so-called pressure regulation failure occurs. In that case, in the invention of the above-mentioned Patent Document 1, since the line pressure is low, hydraulic pressure feedback control including an integral operation is executed, and as a result, the integral term is accumulated and becomes a large value. For this reason, when pressure adjustment is possible due to an increase in the number of engine revolutions, etc., the value of the integral term is accumulated during the pressure regulation failure and becomes a large value, so that the normal pressure regulation state Even so, the control amount based on the control deviation becomes small, and there is a possibility that the response of the control will be lowered transiently.

  The present invention has been made to solve the above technical problem, and an object of the present invention is to suppress an increase in the integral term at the time of pressure regulation failure and to improve the responsiveness after elimination of the pressure regulation failure.

  In order to achieve the above object, the present invention is configured to suppress a decrease in responsiveness after a pressure regulation malfunction period by limiting an increase in an integral term of the pressure regulation malfunction period. It is said. More specifically, the invention of claim 1 is a control of a continuously variable transmission in which an operation state is set by a hydraulic pressure regulated by feedback control including an integral operation based on a deviation between a target value and an actual value. In the apparatus, a pressure regulation failure detecting means for detecting that the hydraulic pressure regulation is defective, and a value of an integral term in the integration operation while the pressure regulation failure is detected by the pressure regulation failure detecting means. And a restricting means for restricting the increase of the control device.

  According to a second aspect of the present invention, in the first aspect of the invention, the limiting means sets the value of the integral term in the integral operation during the adjustment failure to a value immediately before the adjustment failure is detected. It is the control apparatus characterized by including the means to hold | maintain.

  Further, the invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the limiting means includes means for prohibiting the integration operation while being detected by the pressure regulation failure detecting means. It is a control device.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the continuously variable transmission is a belt type continuously variable transmission, and the hydraulic pressure is a clamping pressure for clamping the belt with a pulley. It is the control device characterized.

  According to the first aspect of the present invention, the increase in the value of the integral term in the integral operation is limited while the hydraulic pressure regulation failure is detected. Therefore, there is no increase in the integral term in the so-called abnormal state, so that the integral term in the so-called steady state that has recovered from the poor pressure regulation does not become excessive, and as a result, the hydraulic pressure after the poor restoration of hydraulic pressure regulation is recovered. Responsiveness can be improved.

  According to the second aspect of the present invention, the value of the integral term in the integral operation is maintained at a value immediately before the poor hydraulic pressure regulation is detected while the poor hydraulic pressure regulation is detected. . Accordingly, since the value of the integral term in the further integral operation does not increase, it is possible to improve the response of the hydraulic pressure after recovery of the hydraulic pressure regulation failure.

  Further, according to the invention of claim 3, the integration operation is prohibited while the integration operation is detected as a failure in adjusting the hydraulic pressure. Accordingly, the value of the integral term does not increase, so that the value of the integral term is not output at a time, and the responsiveness of the hydraulic pressure after recovery of the hydraulic pressure regulation failure can be improved.

  According to the invention of claim 4, the continuously variable transmission is a belt type continuously variable transmission, and the hydraulic pressure is a clamping pressure. Therefore, the invention of claims 1 to 3 can be applied to the clamping pressure control of the belt type continuously variable transmission.

  Next, the present invention will be described based on specific examples. First, an example of a drive system including a power source and a continuously variable transmission targeted in the present invention will be described. FIG. 4 schematically shows an example of a drive system including a belt-type continuously variable transmission 1. The continuously variable transmission 1 is connected to a power source 5 via a forward / reverse switching mechanism 2 and a fluid transmission mechanism 4 with a lock-up clutch 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. In the following description, the power source 5 is referred to as the engine 5. The fluid transmission mechanism 4 has a configuration similar to that of, for example, a conventional torque converter, and includes a pump impeller rotated by the engine 5, a turbine runner disposed to face the pump impeller, and a stator disposed therebetween. The turbine runner is rotated by supplying a spiral flow of fluid generated by a pump impeller to the turbine runner, and torque is transmitted.

  In such torque transmission via the fluid, inevitable slip occurs between the pump impeller and the turbine runner, and this causes a reduction in power transmission efficiency. Therefore, the input member such as the pump impeller and the turbine runner A lock-up clutch 3 that directly connects an output side member such as the above is provided. The lock-up clutch 3 is configured to be controlled by hydraulic pressure, and is controlled to a fully engaged state, a fully released state, and a slip state that is an intermediate state between them, and the slip rotation speed can be appropriately controlled. It has become.

  The forward / reverse switching mechanism 2 is a mechanism that is employed when the rotational direction of the engine 5 is limited to one direction, and outputs the input torque as it is or reversely outputs it. It is configured. In the example shown in FIG. 4, a double pinion type planetary gear mechanism is employed as the forward / reverse switching mechanism 2. That is, a ring gear 7 is arranged concentrically with the sun gear 6, and a pinion gear 8 meshed with the sun gear 6 and the pinion gear 8 and another pinion gear 9 meshed with the ring gear 7 are arranged between the sun gear 6 and the ring gear 7. The pinion gears 8 and 9 are held by the carrier 10 so as to rotate and revolve freely. A forward clutch 11 that integrally connects two rotating elements (specifically, the sun gear 6 and the carrier 10) is provided, and the direction of the torque that is output by selectively fixing the ring gear 7 There is provided a reverse brake 12 that reverses.

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

  The hydraulic actuator 16 in the driven pulley 14 is supplied with hydraulic pressure (line pressure or its correction pressure) according to the torque input to the continuously variable transmission 1 via a hydraulic pump and a hydraulic control device (not shown). Yes. Therefore, each sheave in the driven pulley 14 holds the belt 17 so that tension is applied to the belt 17, and a holding pressure (contact pressure) between the pulleys 13, 14 and the belt 17 is ensured. . On the other hand, the hydraulic actuator 15 in the drive pulley 13 is supplied with pressure oil corresponding to the speed ratio to be set, and is set to a groove width (effective diameter) corresponding to the target speed ratio. .

  The driven pulley 14 is connected to a differential 19 through a gear pair 18, and torque is output from the differential 19 to driving wheels 20. Therefore, in the above drive mechanism, the lockup clutch 3 and the continuously variable transmission 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 the vehicle on which the continuously variable transmission 1 and the engine 5 are mounted. That is, a turbine rotation speed sensor 21 that detects an 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 hydraulic pressure sensor 24 that detects the pressure of the hydraulic actuator 16 on the driven pulley 14 side for setting the belt clamping pressure are provided. ing. Although not specifically 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. In this case, a brake sensor for outputting a signal is provided.

  A transmission is used to control the engagement / release of the forward clutch 11 and the reverse brake 12, the control of the clamping force of the belt 17, the control of the transmission ratio, and the control of the lockup clutch 3. An electronic control device (CVT-ECU) 25 is provided. The transmission electronic control unit 25 is configured mainly by a microcomputer as an example, and performs calculations according to a predetermined program based on input data and data stored in advance, and performs various operations such as forward, reverse, or neutral. And the required clamping pressure setting, the gear ratio setting, the engagement / release of the lock-up clutch 3, the slip rotation speed, and the like are executed.

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

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

  In order not to impair such an improvement in fuel consumption, the power transmission efficiency in 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, can transmit the target torque determined based on the engine torque, and the belt clamping pressure is as low as possible without causing the belt 17 to slip. It is controlled to become. For example, the belt clamping pressure controls the continuously variable transmission 1 in a so-called unsteady traveling state such as when acceleration / deceleration is performed relatively frequently or when traveling on a rough road with uneven or uneven road surfaces. It is set to a relatively high pressure such as the line pressure that is the total source pressure in the hydraulic system or its correction pressure.

  On the other hand, in steady running conditions such as running on a flat road at a certain speed or above, or in a quasi-steady running condition equivalent to this, the lowest pressure that can transmit input torque without slipping, that is, the limit clamping pressure In order to detect this, the belt clamping pressure is gradually reduced. The belt clamping pressure is set to a belt clamping pressure obtained by adding a predetermined safety factor or a pressure for setting a margin transmission torque for slipping to the detected limit clamping pressure. The belt clamping pressure in the continuously variable transmission is preferably as low as possible within a range where torque can be transmitted without causing slippage.

  However, when the vehicle suddenly stops from a steady running state or a quasi-steady running state, the rotational speed of the engine is rapidly reduced, and the discharge amount of the oil pump connected to the output shaft of the engine is lowered. Accordingly, the amount of oil in the hydraulic system is reduced, and the hydraulic pressure is reduced. Since the hydraulic system is controlled by PID control so that the pressure becomes constant, an integral value (I value) is output in order to cope with a rapid decrease in hydraulic pressure. The output of the integral value (I value) continues to be output while the oil pressure is decreasing, but the integral value (I value) continues to be output even if the decrease in oil pressure is improved. Therefore, when the engine speed increases and the hydraulic pressure can be controlled, the actual hydraulic pressure increases rapidly. The actual oil pressure drops after the actual oil pressure suddenly rises, but during this time, since the integral value (I value) is also output, the time until the actual oil pressure reaches the target oil pressure is delayed. In order to improve such a delay in the response of the hydraulic control, the following control is performed.

  Note that a routine for executing the following control is repeatedly executed at predetermined time intervals. Further, the integral integration amount in the following embodiment is an accumulation of the integration control amount, and corresponds to the size of the integral term in the feedback control system, that is, the integration value (I value). The integration operation is an operation for accumulating the integration control amount.

  FIG. 1 is a flowchart illustrating an example of control for suppressing a sudden increase in actual hydraulic pressure when recovering from poor pressure regulation. First, it is determined whether the current state is capable of feedback (FB) control (step S101). The state in which feedback control is possible is a state in which various sensors such as a hydraulic sensor are normal, the electromagnetic valve is normal, and the oil temperature is within a predetermined range.

  If a negative determination is made in step S101, that is, if any of the above conditions is not satisfied and it is determined that the feedback control is not possible, normal clamping pressure control is performed (step S111). ) Exit this routine.

  On the other hand, if an affirmative determination is made in step S101, the deviation dltpd (i) between the basic target hydraulic pressure popttgt (i) and the actual hydraulic pressure pscact (i) is calculated, and the variation d_dltpd (i) is further calculated (step S102). ). Then, it is determined whether or not the engine speed Ne (i) is smaller than a predetermined value Ne_min (step S103). When it is determined negative in step S103, that is, when it is determined that the engine speed Ne (i) is larger than the predetermined value Ne_min and the oil amount and the hydraulic pressure are not reduced, normal feedback control is performed. That is, feedback control that does not fix the integral term (I term) is performed (step S110), and this routine is exited.

  If the determination in step S103 is affirmative, that is, if there is a possibility that the engine speed Ne (i) has decreased and the oil amount and the oil pressure have decreased, the determination of the oil pressure decrease is continued. That is, step S103 is a preliminary determination of a decrease in hydraulic pressure.

  The determination of a decrease in hydraulic pressure is performed as follows (step S104). When the deviation dltpd (i) obtained in step S102 is larger than the predetermined value dltpdmax and the deviation change amount d_dltpd (i) obtained in step S102 is larger than the predetermined value d_dltpdmax, the hydraulic pressure is reduced. As a result, the pressure regulation failure determination flag FB_flag (i) is set to “1” (step S106). That is, when the difference between the actual oil pressure pscact (i) and the basic target oil pressure popttgt (i) is large and the amount of change in the difference is increasing, an affirmative determination is made in step S104.

  Thereafter, predetermined control is executed (step S109), and this routine is exited. The predetermined control is a routine for performing a process of integrating the integral values according to the state of the pressure regulation failure flag FB_flag, and details thereof will be described later.

  If a negative determination is made in step S104, that is, the engine speed Ne (i) continues to decrease, the absolute value of the deviation dltpd (i) decreases or the rate of change of the deviation dltpd (i) decreases. If this is the case, it is considered that the pressure drop is being resolved. Therefore, in order to determine whether or not the pressure drop has been resolved, it is determined whether or not the deviation dltpd (i) is smaller than a predetermined value dltpdmin1 (step S105).

  If the determination in step S105 is affirmative, that is, if the deviation dltpd (i) is smaller than the predetermined value dltpdmin1, it is assumed that the pressure drop has been eliminated, and the pressure regulation failure flag FB_flag is set to zero. Thereby, the suppression of integration is stopped in the predetermined control 1 following step S107, normal integration is started (step S109), and this routine is exited.

  On the other hand, if a negative determination is made in step S105, that is, if the pressure drop has not been resolved, the value of the pressure regulation failure flag FB_flag (i-1) at the previous execution is set to the current pressure regulation failure flag FB_flag (i ) And the value of the pressure regulation failure flag FB_flag (i) is maintained. Then, predetermined control 1 is executed (step S109), and this routine is exited.

  Next, details of the predetermined control will be described with reference to the flowchart shown in FIG. First, it is determined whether or not the current pressure regulation failure flag FB_flag (i) is “1” and the pressure regulation failure flag FB_flag (i−1) at the previous execution is “0”. That is, it is determined whether or not the present time is the pressure drop start time (step S201). If the determination in step S201 is affirmative, that is, if the pressure drop start time is reached, the counter N is set to “1” (step S202).

  Then, it is determined whether or not the deviation dltpd (i−N) N cycles before the current time is smaller than a predetermined value dltpdmin2 (step S203). If a negative determination is made in step S203, the counter is incremented (step S204), and the determination is again made in step S203. Then, when the time has elapsed and the determination in step S203 is affirmative, the integral integration amount dltpdttl (iN) before the N time point from the present time, that is, when the deviation dltpd is smaller than the predetermined value dltpdmin2, is calculated as the integration during the decrease in hydraulic pressure. The integrated amount dltpdttlconst is set, and the current integrated integrated amount dltpdttl (i) is set as the integrated integrated amount dltpdttlconst during the decrease in hydraulic pressure (step S205). Then, feedback control is performed using the current integrated integration amount dltpdttl (i) (step S209), and this routine is exited.

  On the other hand, when a negative determination is made in step S201, that is, when the current time is not the time when the pressure reduction starts, it is determined whether or not the pressure regulation failure flag FB_flag (i) is “1” (step S206). That is, it is determined whether or not the current hydraulic pressure reduction state continues. If an affirmative determination is made in step S206, that is, if the oil pressure decrease state is currently continuing, the integral integration amount dltpdttlconst set in step S205 at the first execution of this routine is changed to the current integration integration amount dltpdttl (i ) (Step S207). Then, feedback control is performed using this integral integration amount dltpdttlconst (step S209), and this routine is exited.

  Also, if a negative determination is made in step S206, it is considered that the oil pressure drop has recovered, so the current integrated cumulative amount dltpdttl (i) is changed to the previous integrated cumulative amount dltpdttl (i-1). A so-called normal integration process is performed by adding the deviation dltpd (i) (step S208). Then, feedback control is performed (step S209), and this routine is exited.

  Next, the time course of the above control example will be described with reference to a time chart. When the vehicle suddenly decelerates, the basic target hydraulic pressure is suddenly increased to increase the gear ratio of the continuously variable transmission (time (a) in FIG. 2). Therefore, the deviation dltpd temporarily rises temporarily. Then, the actual oil pressure starts to follow, and the clamping pressure of the driven pulley (secondary pulley) 14 increases (time (a) to (b) in FIG. 2). However, when the vehicle speed further decreases and the engine speed decreases below the threshold value Ne_min, the output of the basic target hydraulic pressure further increases. However, since the engine speed is decreasing, the pumping amount of the oil pump is decreased and the actual hydraulic pressure is decreased.

  When the present invention is not applied, the deviation dltpd increases, so that the integral control amount increases (from (b) to (c) in FIG. 2). The increased integral control amount is accumulated, and is output at once after the engine speed is recovered and the oil pressure drop is recovered. Therefore, the actual oil pressure rapidly increases at the time of this oil pressure recovery (after time (c) in FIG. 2). . Since the integral control amount continues to be output thereafter, there is a delay in the time for the actual hydraulic pressure to drop to the final command value.

  On the other hand, when the present invention is applied (indicated by the alternate long and short dash line in FIG. 2), the deviation dltpd is increased but the time when the deviation dltpd does not exceed the threshold value dltpdmin2 is detected. Is fixed at the value at that time (time (b) in FIG. 2). Therefore, since the integral control amount is accumulated, but the accumulated amount is small, the actual oil pressure quickly decreases to the final command value even if it is output at once after the engine speed is recovered and the oil pressure drop is recovered (FIG. 2). (After time point (c)).

  That is, while the hydraulic pressure regulation failure is detected, an increase in the value of the integral term in the integral operation is limited. Therefore, there is no increase in the value of the integral term in the so-called abnormal state, so that the integral term in the so-called steady state that has recovered from the poor pressure regulation does not become excessive, and as a result, after the recovery of the poor regulation of the hydraulic pressure The hydraulic responsiveness can be improved.

  Further, the value of the integral term in the integral operation is maintained at the value immediately before the detection of the hydraulic pressure regulation failure while the hydraulic pressure regulation failure is detected. Accordingly, since the value of the integral term in the further integral operation does not increase, it is possible to improve the response of the hydraulic pressure after recovery of the hydraulic pressure regulation failure.

  Further, the integration operation is prohibited while the integration operation detects a poor hydraulic pressure regulation. Therefore, since the value of the integral term in the integral operation does not increase, the value of the integral operation is not output at a time, and the responsiveness of the hydraulic pressure after recovering from poor hydraulic pressure regulation can be improved.

  The continuously variable transmission is a belt type continuously variable transmission, and the hydraulic pressure is a clamping pressure. Therefore, the invention of claims 1 to 3 can be applied to the clamping pressure control of the belt type continuously variable transmission.

  Here, the relationship between each of the above specific examples and the present invention will be briefly described. The functional means in step S104 corresponds to the “pressure regulation failure detecting means” in the present invention, and the functional means in step S207 is the present invention. Corresponds to “restricting means”. Further, the functional means in step S205 corresponds to “means for holding at the previous value” in the present invention, and the functional means in step S207 corresponds to “prohibit means” in the present invention. That is, the integral integration amount is set when the predetermined control 1 is executed for the first time, and when the step S207 is executed, the increase in the integration integration amount is stopped. Therefore, step S207 can be said to be a means for stopping the integration operation.

  In addition, this invention is not limited to the said Example. That is, in the above embodiment, the belt type continuously variable transmission has been described. However, this may be applied to a traction type continuously variable transmission. In short, the present invention can be applied to a continuously variable transmission in which the torque capacity to be transmitted can be made variable by controlling the clamping pressure or the line pressure.

It is a flowchart for demonstrating an example of control by the control apparatus of this invention. It is a flowchart for demonstrating predetermined control. It is a time chart for demonstrating an example of control by the control apparatus of this invention. It is a figure which shows typically an example of the drive system containing the continuously variable transmission made into object by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Continuously variable transmission, 5 ... Engine, 13 ... Drive pulley, 14 ... Driven pulley, 15, 16 ... Hydraulic actuator, 25 ... Electronic control unit for transmission (CVT-ECU).

Claims (4)

In a control device for a continuously variable transmission in which an operation state is set by a hydraulic pressure that is regulated by feedback control including an integral operation based on a deviation between a target value and an actual value.
A pressure adjustment failure detecting means for detecting that the pressure adjustment of the oil pressure is defective;
Control of a continuously variable transmission, comprising: limiting means for limiting an increase in the value of an integral term in the integration operation while the poor pressure regulation is detected by the poor pressure regulation detecting means. apparatus.   The limiting means includes means for holding the value of the integral term in the integrating operation at a value immediately before the poor pressure regulation is detected during the poor pressure regulation. Control device for continuously variable transmission.   3. The continuously variable transmission control device according to claim 1, wherein the limiting unit includes a unit that prohibits the integration operation while being detected by the pressure regulation failure detecting unit.   4. The continuously variable transmission according to claim 1, wherein the continuously variable transmission is a belt type continuously variable transmission, and the hydraulic pressure is a clamping pressure for clamping the belt with a pulley. 5. Control device.

Images