JPH02150553A - Line pressure controller for continuously variable transmission - Google Patents

Abstract

PURPOSE:To secure a proper line pressure in a simple logic by compensating the desired line pressure in using an integration valve stored in the last closed loop control as this time correction value when it is changed over to open loop control. CONSTITUTION:When transfer parts 104, 106 and 108 are in a closed-circuit control mode in a full line, a correction value E3P or an integration valve to be secured at time of controlling a line pressure is prestored in a backup memory 203 on the basis of the desired line pressure PLINSP set with throttle opening and belt ratio. When changing over to an open circuit control mode from the closed circuit one, the transfer parts 104, 106 are changed over as in a broken line, and the correction value E3P stored in the last closed circuit control is added to a line pressure duty value U1P out of a map 201, then it is subjected to the open circuit control so as to cause the line pressure to become the desired value. Thus, even if a hydraulic characteristic is varied by a secular change or the like, a proper line pressure is securable by a simple program.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a line pressure control device for a continuously variable transmission.
In particular, the target line pressure for open-loop control can be corrected using a simple program, which simplifies the logic and reduces memory capacity and calculation processing time. The present invention relates to a line pressure control device for a continuously variable transmission that can ensure proper line pressure even when changes occur in hydraulic characteristics.

[Conventional technology]

In vehicles such as automobiles, a transmission is interposed between an internal combustion engine and drive wheels. A transmission changes the driving force transmitted from the internal combustion engine to the drive wheels and the driving speed in accordance with the widely changing driving conditions of the vehicle, thereby allowing the internal combustion engine to fully demonstrate its performance.

This transmission includes a gear type transmission that transmits driving force by changing the gear ratio step by step by selectively switching the meshing state of a multi-stage gear train, and a gear type transmission that transmits driving force by changing the gear ratio in stages. a groove width formed between both pulley parts of a driving pulley and a driven pulley, each having a fixed pulley part and a movable pulley part attached to the rotating shaft so as to be able to approach and separate from the fixed pulley part; There is a continuously variable transmission, etc., which transmits driving force by increasing or decreasing the rotation radius of a belt wound around a pulley and continuously changing the transmission ratio (belt ratio). As a line pressure control device that controls the line pressure that changes the gear ratio of such a continuously variable transmission,
For example, it is disclosed in Japanese Patent Application Laid-Open No. 61233256.

[Problem that the invention seeks to solve]

By the way, when controlling the line pressure for changing the gear ratio to the target line pressure in continuously variable transmission, closed-loop control and open-loop control are used. Closed-loop control controls throttle opening, gear ratio,
Alternatively, the target line pressure is set from a map of engine speed, etc., the difference between this target line pressure and the actual line pressure is integrated to calculate an integral value, and the target line pressure is corrected using the obtained integral value. The line pressure is controlled by feedback as much as possible to the target line pressure. Moreover, open loop control is performed without performing feedbanking so that the line pressure reaches the target line pressure. In addition, when correcting the line pressure, the correction is performed at a point in time when the clutch pressure immediately before the lock amplifier of the hydraulic clutch that connects and connects the driving force of the continuously variable transmission is relatively high.

By correcting the line pressure, when the hydraulic characteristics change due to changes over time or machine differences during production, the target line pressure of open loop control is corrected to ensure an appropriate line pressure, and the line pressure is This prevents inconveniences such as abnormal drops.

However, conventional line pressure correction is based on the clutch pressure immediately before the hydraulic clutch locks up (at this time, the clutch pressure is equal to the line pressure).

) and the target line pressure was used as a correction value, and the target line pressure was corrected using this correction value. However, the programs for calculating the average value and correcting the target line pressure are complicated, and there are disadvantages in that the logic becomes complicated, the memory capacity becomes large, and the calculation processing time becomes long.

[Purpose of the invention]

Therefore, the purpose of the present invention is to correct the target line pressure of open loop control using a simple program, thereby simplifying the logic, reducing memory capacity and calculation processing time, and reducing changes over time and machine differences during production. An object of the present invention is to realize a line pressure control device for a continuously variable transmission that can ensure an appropriate line pressure even when a change in hydraulic characteristics occurs due to reasons such as the following.

[Means for solving problems]

In order to achieve this object, the present invention provides a driving pulley and a driven pulley each having a fixed pulley part and a movable pulley part attached to the fixed pulley part so as to be able to move toward and away from the fixed pulley part. In a continuously variable transmission that changes the gear ratio by increasing or decreasing the groove width between the parts to increase or decrease the rotation radius of the belt wound around both pulleys, the line pressure for changing the gear ratio is closed as much as possible to the target line pressure. Stores the integral value calculated when controlling by loop control,
When the closed-loop control changes to open-loop control, the target line pressure is corrected using the stored integral value from the previous closed-loop control as the correction value for the current open-loop control, and the line pressure becomes the corrected target line pressure. The present invention is characterized in that it is provided with a control means that performs control preferably by open-loop control.

[Effect]

According to the configuration of the present invention, when the control means changes from closed-loop control to open-loop control, the target line pressure is corrected by using the stored integral value in the previous cloved-loop control as a correction value in the current open-loop control. However, by controlling the line pressure to the corrected target line pressure using open-loop control, the target line pressure of open-loop control can be corrected using a simple program.

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings.

1 to 3 show embodiments of this invention.

In FIG. 1, 2 is a belt-driven continuously variable transmission, 2A is a belt, 4 is a driving pulley, 6 is a fixed driving pulley, 8 is a movable pulley on the driving side, 10 is a driven pulley, 12 is a fixed pulley piece on the driven side, and 14 is a movable pulley piece on the driven side.

The drive-side pulley 4 includes a drive-side fixed pulley piece 6 fixed to a rotation shaft 16 serving as an input shaft, and a drive-side fixed pulley piece 6 attached to the rotation shaft 16 so as to be movable in the axial direction of the rotation shaft 16 but not rotatable. It has a movable pulley piece 8. Further, similarly to the driving pulley 4, the driven pulley 1o has a rotating shaft 17 serving as an output shaft, a fixed driven pulley piece 12, and a movable driven pulley piece 14.

First and second housings 18.20 are attached to the drive side movable pulley piece 8 and the driven side movable pulley piece 14, respectively, and first and second hydraulic chambers 22.24 are formed, respectively. . The hydraulic pressure receiving area of the driving side movable pulley part 8 of the first hydraulic chamber 22 is set to be larger than the hydraulic pressure receiving area of the driven side pulley part 14 of the second hydraulic chamber 24 . This allows the first
By controlling the hydraulic pressure acting on the hydraulic chamber 22, the belt ratio, which is a gear ratio, is changed. Also, the second
Inside the hydraulic chamber 24, there is a spring, etc. that biases the driven side movable pulley piece 14 in a direction that reduces the groove width between the driven side fixed pulley piece 12 and the driven side movable pulley piece 14. A biasing means 26 is provided. This biasing means 26 provides a large gear ratio on the full-low side when the oil pressure is low, such as at the time of starting, and maintains the holding force of the bell 2A to prevent slippage.

An oil pump 28 is provided on the rotating shaft 16, and the oil pump 28 is connected to the first and second hydraulic chambers 22, 24.
and a second oil passage 30, 32, and a primary pressure control valve 34, which is a speed change control valve, that controls a primary pressure, which is an input shaft sheave pressure, is interposed in the middle of the first oil passage 30. This first oil passage 30, which is closer to the oil pump 28 than the primary pressure control valve 34, has a third
Line pressure (generally 5 to 25 km
/a() is connected to a constant pressure control valve 38 which controls and takes out the control oil pressure at a constant pressure (3 to 4 km/CIA),
A first three-way solenoid valve 42 for primary pressure control is communicated with the primary pressure control valve 34 through a fourth oil passage 40 .

Further, in the middle of the second oil passage 32, a line pressure control valve 44 having a relief valve function for controlling line pressure, which is pump pressure, is communicated with a fifth oil passage 46, and a sixth oil passage The oil passage 48 communicates with a second three-way solenoid valve 50 for controlling line pressure.

Further, in the middle of the second oil passage 32 on the side of the second hydraulic chamber 24 with respect to the communicating portion of the line pressure control valve 44, there is a clutch pressure control valve 52 for controlling clutch pressure, which is a hydraulic pressure acting on a hydraulic clutch 62, which will be described later. are communicated through a seventh oil passage 54, and an eighth oil passage 5 is connected to this clutch pressure control valve 52.
6 communicates with the third three-way solenoid valve 58 for clutch pressure control.

Further, the constant pressure control hydraulic pressure taken out from the constant pressure control valve 3B is transferred to the primary pressure control valve 34, the first three-way solenoid valve for primary pressure control 42, and the line pressure control valve 44.
and second three-way solenoid valve 50 for line pressure control, clutch pressure control valve 52, and third three-way solenoid valve 58 for clutch pressure control, respectively.
44, 50, and 52 are communicated with each other through a ninth oil passage 60.

The clutch pressure control valve 52 communicates with the clutch hydraulic chamber 72 of the hydraulic clutch 62 through a tenth oil passage 64, and there is a first oil passage in the middle of the tenth oil passage 64.
1 oil passage 66 communicates with a pressure sensor 68. This pressure sensor 68 can directly detect the oil pressure when controlling the clutch pressure in the hold mode, start mode, etc., and contributes to instructing the detected oil pressure to be the target clutch pressure. Furthermore, since the clutch pressure becomes equal to the line pressure in the drive mode, it also contributes to line pressure control.

The hydraulic clutch 62 includes an input-side casing 70 attached to the rotating shaft 17, a clutch hydraulic chamber 72 provided within the casing 70, and a piston 74 pushed by hydraulic pressure acting on the clutch hydraulic chamber 72. , an annular spring 7G that urges this piston 74 in the retirement direction, a pushing force of the piston 74, and an annular spring 7
6, a friction plate 80 on the output side, and a second pressure plate 82 fixed to the casing 70.

In the hydraulic clutch 62, when the clutch pressure, which is the hydraulic pressure applied to the clutch hydraulic chamber 72, is increased, the piston 74 is pushed forward to bring the first pressure coupler 78 and the second pressure coupler 82 into close contact with the friction plate 80, resulting in a so-called coupled state. become. On the other hand, when the clutch pressure, which is the hydraulic pressure applied to the clutch hydraulic chamber 72, is lowered, the piston retires due to the biasing force of the annular spring 76, and the first plate 78 and the second
The pressure plate 82 is separated from the friction plate 80, resulting in a so-called clutch disengagement state. By engaging and disengaging the hydraulic clutch 62, the driving force output from the continuously variable transmission 2 is intermittent.

An input shaft rotation detection gear 84 is provided on the outside of the first housing 18.
A first rotation detector 86 on the input shaft side is provided near the outer peripheral portion of the input shaft rotation detection gear 84. Further, an output shaft rotation detection gear 88 is provided on the outside of the second housing 20, and a second rotation detector 90 on the output shaft side is provided near the outer peripheral portion of the output shaft rotation detection gear 88. The engine rotation speed and belt ratio are determined from the rotation speed detected by the first rotation detector 86 and the second rotation detector 90.

The hydraulic clutch 62 also includes an output transmission gear 92.
has been established. This output transmission gear 92 is made up of a forward output transmission gear 92F and a backward force transmission gear 92R, and a third rotation detection device that detects the number of rotations of the final output shaft 94 is located near the outer circumference of the backward force transmission gear 92R. A container 96 is provided. This third rotation detector 96 detects the rotation speed of a final output shaft 94 connected to wheels (not shown), and is capable of detecting vehicle speed. Furthermore, the second rotation detector 90
According to the rotation speed detected by the third rotation detector 96, it is also possible to detect the rotation speed of the input side and output side before and after the hydraulic clutch 62, which contributes to the detection of the amount of thalassostatic pressure.

the pressure sensor 68 and first to third rotation detectors 8G;
It is a control means that performs control by inputting various signals such as carburetor throttle opening, carburetor idle position, accelerator pedal signal, brake signal, power mode option signal, shift lever position, etc. in conjunction with various signals from 90.96. A control section 98 is provided. The control unit 98 controls the first three-way solenoid valve 42 for primary pressure control and the second three-way solenoid valve 5 for line pressure control in order to control the belt ratio and clutch engagement/disengagement state in various control modes based on various input signals.
0, and controls the opening/closing operation of the third three-way solenoid valve 58 for clutch pressure control.

Note that the reference numeral 100 is an oil pan and the reference numeral 102 is an oil filter.

In detail, the functions of the input signals input to the control section 98 are as follows: (1) Shift lever position detection signal... Each range is controlled by each range signal such as P, R, N, D, L, etc. line pressure and ratio required for, clutch control ■, detection signal of caplet rotation opening degree...
Detects the engine torque from the memory input into the program in advance, determines the target ratio or target engine speed, detects the carburetor idle position, and improves accuracy in correction and control of the carburetor throttle opening sensor. , Accelerator pedal signal: Detects the driver's intention based on the state of depression of the accelerator pedal and determines the direction of control when driving or starting ■, Brake signal: Detects the driver's intention based on the state of depression of the accelerator pedal. Detects the presence and determines the control direction such as clutch disengagement■, Power mode option signal...It is used as an option to make the performance of the vehicle more sporty (or more economical).

The line pressure control valve 44 has a shift control characteristic that performs three-stage control by changing the line pressure in a full low state, a full over top state, and a fixed ratio state.

The operation of the primary pressure control valve 34 that controls the primary pressure for speed change control is controlled by a first three-way solenoid valve 42 for primary pressure control, similar to the line pressure control valve 44 described above. This first three-way solenoid valve 42 for primary pressure control is used to control the operation of the primary pressure control valve 34 to conduct the primary pressure to the first oil passage 30 or to conduct the primary pressure to the atmosphere side. . The primary pressure control valve 34 shifts the belt ratio to the full overdrive side by conducting the line pressure to the first oil passage 30, or shifts the belt ratio to the full low side by conducting the line pressure to the atmosphere side.

The clutch pressure control valve 52 that controls the clutch pressure conducts the line pressure to the 10th oil passage 64 side when the maximum clutch pressure is required, and conducts the line pressure to the atmosphere side when the minimum clutch pressure is required. be. This clutch pressure control valve 5
2 is the line pressure control valve 44 and the primary pressure control valve 3.
4, the operation is controlled by a dedicated third three-way electromagnetic valve 58 for clutch pressure control, so a description thereof will be omitted.

The clutch pressure varies within a range from the lowest atmospheric pressure (zero) to the highest line pressure. There are four basic patterns for this clutch pressure control, and these basic patterns are +11, neutral mode...When the clutch is completely disengaged with the shift position N or P, the clutch pressure is the lowest pressure ( zero) (2),
Hold mode: When the shift position is D or R and you release the throttle and have no intention of driving, or when you want to decelerate and cut off the engine torque while driving, the clutch pressure is set to a low level that the clutch contacts ( 3) Start mode (special start mode) ...When starting (normal start) or when trying to re-engage the clutch after the clutch has been disengaged (
special start), the clutch pressure is set at an appropriate level (4) according to the engine generated torque (clutch input torque) to prevent the engine from revving up and to allow the vehicle to operate smoothly, and the drive mode... When the vehicle enters a running state and the clutch is fully engaged, there are four levels of clutch pressure that are high enough to withstand engine torque.

(1) of these four basic patterns is performed by a dedicated switching valve (not shown) that is linked to the shift operation.

The other (2), (3), and (4) are performed by the duty value control of the first to third three-way solenoid valves 42, 50, and 58 by the control section 98. Particularly in the state (4), the clutch pressure control valve 52 controls the seventh oil passage 54.
The clutch pressure and the tenth oil passage 64 are communicated with each other to generate a maximum pressure, and the clutch pressure is made equal to the line pressure.

In addition, the primary pressure control valve 34 and the line pressure control valve 4
4, and the clutch pressure control valve 52 is controlled by the output oil pressure from the first to third three-way solenoid valves 42, 50, and 58, respectively. These first to third three-way solenoid valves 42.50.
The control hydraulic pressure that controls the constant pressure control valve 3
8 is a constant control oil pressure taken out by 8.

This control oil pressure is always lower than the line pressure, but is a stable and constant pressure. Control hydraulic pressure is also introduced to each control valve 34, 44, 52 to stabilize these control valves 34, 44, 52.

In such a continuously variable transmission 2, the control unit 98:
The integral value calculated when the line pressure for changing the gear ratio is controlled by closed-loop control as much as the target line pressure is stored, and when the closed-loop control becomes open-loop control, the stored previous closed-loop control is stored. The target line pressure is corrected using the integral value in the loop control 7 control as a correction value in the current open loop control, and the open loop control is used to control the line pressure to the target line pressure.

Control by this control section 98 will be explained with reference to FIG. 2.3.

In the figure, PLINSP: Target line pressure PCLU: Clutch pressure 0PWLINE Line pressure duty value LPFF: Map of target line and line pressure output duty value Closed loop control mode LOLMOD that feedbanks this PCLU. 0PW at LPFF in new start mode
Oven loop control mode that sets and outputs LIN (line pressure duty value) LHOMOD: Open loop control mode that sets and outputs 0PWLIN in the same way as LoLMOD in hold mode LDIMOD: opwLIN = in neutral mode
This is an open loop control mode that outputs 0.

In the line pressure control mode by the control section 98, as shown in FIG. 2, in the LCLMOD, the first switching section 10
4. The second switching section 106 and the third switching section 10B are switched as shown by the solid line. In this LCLMOD, PLINSP is read from the map set by the throttle opening and belt ratio (200), and UIP, which is the line pressure output duty value, is converted from LPFF by this PLINSP.
is calculated (201). Furthermore, the actual line pressure (here, since the hydraulic clutch 62 is locking up,
Line pressure = clutch pressure (PCL U).

) is fed back (202), and a correction value E2P as an integral value is calculated from the difference (203).

This E2P is added to the UIP (204) and output as 0PWLIN, which is the line pressure output duty value (204).
05), the line pressure is controlled by feedbanking as much as possible to reach the target line pressure.

The correction value E2P, which is the integral value calculated each time by this LCLMOD, is obtained by non-integral control with PLINSP-PCLU=0 (202), so the difference from LPFF, which is an open loop map, can actually be obtained. become.

Therefore, as a learning control to correct the line pressure, the line pressure control mode shifts to closed-loop LCLMOD, and after the hydraulic clutch 62 is locked up (line pressure = clutch pressure (PCLU)), and PCLU > 10 kg/c
a (This is to improve control accuracy by correcting on the high pressure side where the clutch pressure is equal to the line pressure.). I'll keep it. The correction using the correction value E2P is performed in a positive direction on the safe side of the line pressure. This is to prevent the line pressure from decreasing due to a malfunction in the hydraulic circuit. ) and performs limiter processing to obtain a new correction value E3P (206).

In this way, the correction value E3P, which is the integral value obtained during the closed-loop control LCLMOD, is stored in the bank amplifier memory.

From the closed loop control LCLMOD to the open loop control LHOMOD or LOLMO
When it reaches D, the first switching section 104 and the second switching section 106
is switched as shown by the broken line, and the third switching section 108 is switched as shown by the solid line.

As a result, the correction value E3P (206), which is the memorized integral value obtained in the previous LCLMOD, is transferred to LPFF (2).
It is added to the line pressure output duty value U'IP from 01) and corrected, and output as 0PWLIN 8205)l, .
The line pressure is controlled by open loop control so as to reach the target line pressure. Thereby, even if the hydraulic characteristics change due to aging or the like, appropriate line pressure can be ensured. Furthermore, the program is simple, and the memory capacity and calculation processing time can be reduced.

Note that when the mode becomes LDIMOD, the third switching unit 108 switches as shown by the broken line and outputs 0PWLIN as 0.

Next, line pressure control will be explained with reference to FIG.

Note that the line pressure control mode determination is determined based on the driving state of the vehicle using the same logic as in the prior art, and a description thereof will be omitted.

When control starts (300), it is determined whether or not it is LCLMOD (301). If YES, calculate the line pressure output duty value UIP from LPFF 302
), the actual line pressure (here, the hydraulic clutch 62 is locked up, so it is line pressure - clutch pressure (PCLU)) is fed back through a closed loop, and the difference is used as a correction value, which is an integral value. Some E2
Get P.

Next, it is determined whether PCLU is less than or exceeds 10 kg/cd (304) L, PCLU>10 kg/cd
If it is cIll, the E2P is subjected to limiter processing to obtain a new E3P as a correction value, which is stored in the back amplifier memory to update the previous E3P (305).

In the judgment in step 304, PCLU≦10kg
/cJ, E2F is added to the UIP obtained in step 302.
is added and corrected to obtain 0PWLIN (306). Apply upper and lower limit processing of 5 to 95% of this 0PWLIN and 30
7) Output 0PWL IN (308) L, return (309). With this 0PWLIN, the line pressure is controlled by closed loop control so as to reach the target line pressure.

On the other hand, if the determination at step 301 is NO, it is determined whether or not it is LOLMOD (31'0). YES
In this case, calculate the UIP from the LPFF (311), and add the E3P stored in the step 306 to this UIP.
is added and corrected to obtain 0PWL IN (312).

The obtained 0PWLIN is 5 in step 307.
~95% upper and lower limit processing is performed and OP is performed in step 308.
Output WLIN and return (309). This 0P
By WL I N, the line pressure is controlled by open loop control so as to reach the target line pressure.

Further, if the determination at step 310 is NO, it is determined whether it is LHOMOD (313). If YES, calculate UIP from LPFF (314) L, add and correct E3P stored in step 305 to this UIP, and obtain 0PWL IN (315). The obtained O PWLIN is 5 in step 307.
~95% upper and lower limit processing is performed and OP is performed in step 308.
Outputs WLIN and returns (309). This 0PW
The LIN is used to control the line pressure to the target line pressure using open loop control.

Furthermore, if the determination in step 313 is NO, it is determined whether or not it is an LDIMOD (316). YES
(7) If 0PWLIN is 0 (OPWLIN=O)
317) and return (309). If NO, return (309).

In this way, LCLMOD, which is closed-loop control,
LHOMOD or - which is open loop control from
When L OL M OD is reached, the correction value E3P, which is the memorized integral value obtained in the previous LCLMOD, is set to 0PFF.
It is added to UIP, which is the line pressure output duty value from , is corrected, and output as 0PWLIN, and the line pressure is controlled by open loop control so as to reach the target line pressure. Thereby, even if the correction characteristics change due to changes over time, etc., it is possible to ensure an appropriate line pressure. Moreover, the program is simple, and the memory capacity and calculation processing time can be reduced.

In this embodiment, the line pressure is corrected only in the positive direction, but the basic idea is that the integral value E2P calculated by closed-loop control is the duty value output from the oven loop map LPFF and its duty value. Since the integrated value E2P is obtained from the difference between the line pressure and the line pressure controlled by the target oil pressure, the integral value E2P is a value obtained by converting the amount of change in the hydraulic circuit with respect to the target oil pressure into a duty value. Therefore, for correction of this hydraulic circuit, if this integral value E2P is used not only in the positive direction but also in the negative direction as in this embodiment, a more accurate line pressure can be obtained with respect to the target line pressure. That is clear.

〔Effect of the invention〕

As explained in detail above, according to the present invention, when the control means changes from closed-loop control to open-loop control, the stored integral value in the previous closed-loop control is set as the target correction value in the current open-loop control. By correcting the line pressure and controlling the line pressure to the corrected target line pressure using open-loop control, the target line pressure of open-loop control can be corrected using a simple program.

This simplifies the logic, reduces memory capacity and calculation processing time, and even when hydraulic characteristics change due to changes over time or machine differences during production, it can also be used on the line during use. Appropriate line pressure can be ensured even if a change occurs in the pressure hydraulic circuit.

Furthermore, there is no need to add new hardware;
This can be done by simply changing the software, and it is easy to run the program and check the functionality, and most of the existing programs can be used.
It is possible to reduce the amount of memory increase in the control section, prevent unnecessary increases in cost, and is economically advantageous.

[Brief explanation of the drawing]

1 to 3 show embodiments of the present invention, FIG. 1 is a block diagram of a continuously variable transmission, FIG. 2 is a control block diagram, and FIG. 3 is a block diagram of a continuously variable transmission.
The figure is a control flowchart. In the figure, 2 is a belt-driven continuously variable transmission, 2A
is the belt, 4 is the driving pulley, 10 is the driven pulley,
34 is a primary pressure control valve, 38 is a constant pressure control valve, 42 is a primary pressure control valve, 38 is a constant pressure control valve, 42 is a first three-way solenoid valve for primary pressure control, 44 is a line pressure control valve, 50 is a life pressure control valve 52 is a clutch pressure control valve, 58 is a third three-way solenoid valve for clutch pressure control, 62 is a hydraulic start clutch, 68 is a pressure sensor, 84 is an input shaft rotation detection gear, 90 is a second rotation Detector, 96 is an output transmission gear, 98 is a control section, 104 is a first switching section, 106 is a second
The switching section 108 is a third switching section.

Claims (1)

[Claims] 1. Increasing or decreasing the groove width between the two pulley parts of each of the driving pulley and the driven pulley, which have a fixed pulley part and a movable pulley part attached to the fixed pulley part so as to be removable. In a continuously variable transmission that changes the speed ratio by increasing or decreasing the rotation radius of a belt wound around both pulleys,
The integral value calculated when the line pressure for changing the gear ratio is controlled by closed-loop control as much as the target line pressure is stored, and when the closed-loop control becomes open-loop control, the stored previous closed-loop control is stored. The continuous control system is characterized by comprising a control means for correcting the target line pressure by using the integral value in the loop control as a correction value in the current open-loop control, and controlling the line pressure to the corrected target line pressure by open-loop control as much as possible. Line pressure control device for variable transmission.