JPH0694049A - Clutch control method for continuously variable transmission - Google Patents

Abstract

PURPOSE:To improve the extent of start feeling by controlling a clutch pressure by a start mode after installing this clutch pressure once higher than that at the time of a hold mode, when clutch pressure control over a hydraulic clutch is operated to start at the time of the hold mode. CONSTITUTION:During a hold mode (HLD) of a hydraulic clutch, there is a driver's intention of starting this car, namely, when an accelerator pedal is operated and its throttle opening becomes enlarged, a driver demand switch is turned to ON from OFF (an A position in fig.). But transition from the hold mode (HLD) to a normal start mode (NST) is not carried out at once, first of all, clutch pressure (PCLU) is set to clutch pressure (MPCLU) once higher as much as a specified value (h) than clutch pressure (HPCLU) in time of the hold mode (HLD), and then at a B position elapsed as long as time (t1) from the A position, it is set to the normal start mode (NST). In succession, at a C position after elapsed as long as time (t2) from the B position, clutch starting control is thus started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch control method for a continuously variable transmission, and particularly when the clutch pressure control of a hydraulic clutch shifts to a start mode, the clutch pressure is temporarily increased by a predetermined amount and then shifts to a start mode. By letting
In addition to preventing problems during start-up operation,
The present invention relates to a clutch control method for a continuously variable transmission that can improve the starting feeling.

[0002]

2. Description of the Related Art In a vehicle, a transmission is interposed between the internal combustion engine and the wheels because the characteristics of the internal combustion engine are not suitable as they are. This transmission changes the driving force and the rotational speed of the wheels in accordance with the traveling conditions of the vehicle that change over a wide range, so that the performance of the internal combustion engine is fully exhibited.

As a transmission, there is a continuously variable transmission in which a gear ratio (belt ratio) is continuously changed by changing a radius of rotation of a belt wound around a driving pulley and a driven pulley.

Some continuously variable transmissions are equipped with a hydraulic clutch that connects and disconnects the driving force of the internal combustion engine by means of hydraulic pressure.

In this hydraulic clutch, various signals such as the engine speed, the throttle opening of the carburetor throttle valve, the position of the shift lever, etc. are input to the control section, and the various control modes (control mode) determined by this control section. ) Is controlled by the clutch pressure changed according to (1).

Various control modes of the hydraulic clutch include, for example, a neutral mode, a hold mode, a normal start mode and a drive mode as the start mode.

The neutral mode is determined when the position of the shift lever is parking "P" or neutral "N", and the hydraulic clutch is completely disengaged. When the clutch pressure to the hydraulic clutch is zero. is there.

The hold mode is determined by the position of the shift lever, the engine speed, the vehicle speed, and the depression state of the accelerator pedal. That is, in this hold mode, the shift lever position is drive "D", low "L", or reverse "R", engine speed <1000 rpm, and the clutch output shaft of the hydraulic clutch rotates (vehicle speed). ) <8
It is determined when the condition of 〓 / h and the condition that the accelerator pedal switch is off, that is, the accelerator pedal is not depressed and the driver does not intend to drive the vehicle are satisfied. In this hold mode, the clutch pressure of the hydraulic clutch is feedback controlled by the clutch solenoid duty output signal to the clutch solenoid valve so that the clutch pressure target value will be 3.5〓 / 〓 ² (clutch engagement pressure). To be done. The clutch duty output signal is a pulse signal output from the controller, and controls the operation of the clutch solenoid valve by changing the duty ratio. That is, in this hold mode, when there is no intention to drive the vehicle, or when it is desired to decelerate during traveling to cut off the engine torque. Further, the clutch pressure of the hydraulic clutch is maintained at a low value such that the engine torque is hardly transmitted but the hydraulic clutch is slightly engaged.

The normal start mode is determined by the position of the shift lever, the engine speed, the vehicle speed, and the depression state of the accelerator pedal. That is, in this normal start mode, the position of the shift lever is drive "D", low "L", or reverse "R", and the vehicle speed is <8 〓 /
The condition of h, the condition that the accelerator pedal is depressed and the accelerator pedal switch is turned on, and the engine speed ≧ 1000 rp
It is determined when the condition of m is satisfied. In this normal start mode, the engine generated torque (clutch input torque) is generated when the vehicle starts or when the hydraulic clutch is re-engaged after the clutch is disengaged.
Is applied to the hydraulic clutch, whereby the clutch pressure is maintained at an appropriate value with quick responsiveness in order to prevent the internal combustion engine from rising and to smoothly start the vehicle.

The drive mode is determined by the position of the shift lever, the vehicle speed and the clutch slip amount. That is, in this drive mode, the position of the shift lever is drive "D", low "L", or reverse "R",
Vehicle speed ≧ 8〓 / h and clutch slip amount ≦ 20r
It is judged when pm is satisfied. In this drive mode, the vehicle shifts to the complete running state and the hydraulic clutch is fully engaged (clutch lockup state), or the hydraulic clutch locks up substantially when shifting from the normal start mode. Is in a state of
When the vehicle completely shifts to the running state and the hydraulic clutch is completely engaged, a high clutch pressure (maximum clutch pressure) with sufficient margin to withstand the engine torque is applied to the hydraulic clutch.

In the hydraulic clutch of the continuously variable transmission, creep control is performed in the hold mode (HLD) as shown in FIG. This creep control is control for causing the clutch pressure (PCLU) to the hydraulic clutch to follow the clutch pressure target value (CPSP) determined by the engine speed (NE). In other words, in this creep control, the clutch pressure target value (CPS
P) is determined, the clutch solenoid duty output signal is adjusted so that the clutch pressure (PCLU) matches the clutch pressure target value (CPSP), and stronger creep is controlled as the engine speed (NE) is higher. The creep amount is increased when the vehicle moves backward rather than when the vehicle moves forward.

In the clutch pressure control of the hydraulic clutch, when the line pressure control and the clutch pressure control are performed at the same time when the hold mode (HLD) is switched to the normal start mode (NST), the calculation and the hydraulic pressure are performed. Line pressure (PLINE) required for clutch pressure control due to delay in
However, there is a control method in which the line pressure control is started immediately after shifting to the normal start mode, but the clutch pressure control is delayed by a predetermined time (JP-A-1-119433).

According to the technique disclosed in Japanese Patent Laid-Open No. 1-119433, the start time of clutch pressure control of the hydraulic clutch in the start mode is delayed by a predetermined time when the hydraulic clutch shifts from the hold mode to the start mode. The engine speed is prevented from fluctuating, a predetermined engine speed is secured, and a sufficient line pressure without fluctuation is secured to easily perform clutch pressure control of the hydraulic clutch.

[0014]

However, in the conventional clutch control method provided in the continuously variable transmission, as shown in FIG. 5, the position of the shift lever is set to drive "D" while the vehicle is stopped. Low "L" or reverse "R"
In the hydraulic clutch, creep control is performed in the hold mode (HLD), and the driving force of the internal combustion engine is transmitted to the wheels via the hydraulic clutch. At this time, the clutch pressure target value (CPSP) is normally 4.5 〓 / 〓 ² rank.

As shown in FIG. 5, when the driver depresses the accelerator pedal or the like to start the vehicle (position a in FIG. 5), the control mode of the hydraulic clutch changes from the hold mode (HLD) to the normal start mode. Immediately shift to (NST). At this time, in the hydraulic clutch, the creep control shifts to the clutch start control in a short time (position b in FIG. 5).

The clutch pressure target value (CPSP) in the clutch starting control is at least 10 〓 / 〓 ² or more. That is, as from the hold mode (HLD) to transition to the normal start mode (NST), the clutch pressure target value (CPSP) is, 10〓 from 4.5〓 / 〓 ² / 〓 ²
It will increase rapidly.

A delay in following the clutch pressure (PCLU) with respect to the change in the clutch pressure target value (CPSP) will inevitably occur, but this delay is caused by the clutch pressure target value (CPS).
The larger the change in P) is, the more remarkable it is.

As a result, the normal start mode (NS
Immediately after the clutch start control in T), as shown in the position e of FIG. 5, problems such as engine speed (NE) upswing, drop, swell, etc. occur, or the start control is not performed smoothly. There was a problem that the starting feeling deteriorated.

[0019]

SUMMARY OF THE INVENTION Therefore, in order to eliminate the above-mentioned inconvenience, the present invention changes the radius of gyration of a belt wound around a driving pulley and a driven pulley to continuously change a gear ratio. In a clutch control method for a continuously variable transmission for a vehicle, a hydraulic clutch whose discontinuous state is controlled by various control modes is provided, and various signals are input to change the clutch pressure to the hydraulic clutch by following a clutch pressure target value. A control unit is provided for controlling the clutch pressure of the hydraulic clutch by the control unit when the starting operation of the vehicle is performed in the hold mode among the various control modes, the clutch pressure is controlled before shifting to the start mode. The clutch pressure in the hold mode is once increased by a predetermined amount, and the clutch pressure of the hydraulic clutch is controlled in the start mode.

[0020]

According to the clutch control method of the present invention, when the starting operation of the vehicle is performed in the hold mode among the various control modes of the clutch pressure control of the hydraulic clutch, the clutch pressure is controlled before shifting to the start mode. The clutch pressure in the hold mode is once increased by a predetermined amount, and the clutch pressure of the hydraulic clutch is controlled in the start mode. As a result, when the driver performs a start operation to indicate the intention to start the vehicle, the clutch pressure is temporarily increased by a predetermined amount and then the start mode is entered to perform the clutch start control. It is possible to prevent the occurrence of troubles in the vehicle and improve the starting feeling.

[0021]

Embodiments of the present invention will be described in detail and specifically with reference to the drawings. In FIG. 4, reference numeral 2 denotes a continuously variable transmission that is mounted on a vehicle and transmits the driving force of an internal combustion engine (not shown) to the wheels. The continuously variable transmission 2 includes a drive pulley (primary pulley) 4, a driven pulley (secondary pulley) 6, and a belt 8 wound around the drive pulley 4 and the driven pulley 6, and is hydraulically controlled. The radius of gyration of the lever 8 is changed to continuously change the gear ratio.

The drive pulley 4 is a drive shaft 10 connected to an internal combustion engine, a drive-side fixed pulley portion 12 integrally provided on the drive shaft 10, and is movable in the drive shaft 10 in the axial direction. The drive-side movable pulley portion 14 is provided so as not to rotate. A drive side belt groove 16 around which the belt 8 is wound is formed between the drive side fixed pulley portion piece 12 and the drive side movable pulley portion piece 14. Further, on the back side of the drive side movable pulley section piece 14, a drive side housing 20 that cooperates with the back side of the drive side movable pulley section piece 14 to form a drive side hydraulic chamber 18 is fixedly installed on the drive shaft 10. There is. A drive shaft side oil passage 22 formed at an end portion of the drive shaft 10 is connected to the drive side hydraulic chamber 18.

An oil pump 24 is provided on the back side of the drive-side fixed pulley portion 12. The oil pump 24 is supported by a pump housing 26 fixed to the drive shaft 10. This oil pump 2
4 is an oil suction passage 30 that is driven by the rotation of the drive shaft 10 and connects the oil in the oil pan 28 to the suction side.
It is sucked from and discharged from the discharge side to a hydraulic control system or a lubrication system. The oil suction passage 3 is provided in the oil pan 28.
An oil strainer 32 is attached to the opening portion of the oil suction passage 30 in order to filter the oil to 0.

The driven pulley 6 is arranged in parallel with the drive shaft 10 and a driven shaft 34 disposed corresponding to the drive side movable pulley portion 14 and provided integrally with the driven shaft 34. A side fixed pulley section piece 36, and a driven side fixed pulley section piece 38 which is arranged corresponding to the drive side fixed pulley section piece 12 and is axially movable and non-rotatably provided on the driven shaft 34. is doing. Driven side fixed pulley part 36
A driven-side belt groove 40 around which the belt 8 is wound is formed between the driven-side movable pulley portion 38 and the driven-side movable pulley portion 38. Further, on the rear surface side of the driven-side movable pulley portion piece 38, a driven-side housing 44 that cooperates with the back surface of the driven-side movable pulley portion piece 38 to form the driven-side hydraulic chamber 42 is fixed to the driven shaft 34. There is. A driven shaft side oil passage 46 formed at an end portion of the driven shaft 34 communicates with the driven side hydraulic chamber 42.

In the driven hydraulic chamber 42, the driven movable pulley portion 38 is pressed to the driven fixed pulley portion 36 side between the rear surface of the driven movable pulley portion 38 and the driven housing 44. The spring 48 is contracted.
This spring 48 has a minimum belt holding force for keeping the gear ratio low and preventing the belt 8 from slipping even when the rotation speed of the oil pump 24 is low and the line pressure (pump pressure) is low when the internal combustion engine is started. Is given.

A hydraulic clutch 50 is provided on the rear side of the driven side fixed pulley portion 36.

The hydraulic clutch 50 is provided so as to be movable in the axial direction on the driven shaft 34 so as to slide in the clutch casing 52 fixed to the outermost end portion of the driven shaft 34 and the step portion 54 of the clutch casing 52. Pressed piston 56
A clutch hydraulic chamber 58 formed between the clutch casing 52 and the pressing piston 56, and the clutch hydraulic chamber 5
8 is a diaphragm spring 60 for urging the pressing piston 56 in the direction of contraction, and the shaft of the driven shaft 34 for moving in the axial direction of the driven shaft 34 by the pushing force of the pressing piston 56 and the urging force of the diaphragm spring 60. A pressure plate 64 slidably provided on an outer peripheral edge portion 62 of the clutch casing 52 positioned substantially parallel to the direction, an end plate 66 connected to an end portion of the outer peripheral edge portion 62 of the clutch casing 52, and a pressure It has a friction plate 70 disposed in a clutch space 68 between the plate 64 and the end plate 66. The clutch hydraulic chamber 5
A driven shaft clutch oil passage 72 formed at an end portion of the driven shaft 34 is communicated with 8.

The friction plate 70 is connected to a clutch output shaft 74 rotatably provided on the driven shaft 34.

In this hydraulic clutch 50, when the clutch pressure, which is the hydraulic pressure applied to the clutch hydraulic chamber 58, is increased, the pressing piston 56 is pushed forward, and the pressure plate 64 is pushed forward by the urging force of the diaphragm spring 60. The pressure plate 64 makes the friction plate 70 adhere to the end plate 66,
The hydraulic clutch 50 is in the connected state, that is, the connected state.
On the other hand, when the clutch pressure applied to the clutch hydraulic chamber 58 is lowered, the pressing piston 56 is moved in the contracting direction of the clutch hydraulic chamber 58 by the urging force of the diaphragm spring 60, and the friction plate 70 is separated from the end plate 66, The hydraulic clutch 50 is disengaged. Therefore, this hydraulic clutch 50
It is engaged / disengaged depending on the clutch pressure state to interrupt the driving force to the clutch output shaft 74 side.

Clutch hydraulic chamber 5 of the hydraulic clutch 50
A clutch pressure (PCLU) changed according to various control modes (control mode) is applied to 8 by a control unit 134 described later.

Various control modes of the hydraulic clutch 50 include, for example, a neutral mode (NEU), a hold mode (HLD), and a normal start mode (NS).
T), drive mode (DRV), etc.

The neutral mode (NEU) is determined when the position of the shift lever is in the parking "P" or the neutral "N", and the hydraulic clutch 50 is completely disengaged. It is zero.

The hold mode (HLD) is determined by the position of the shift lever, the engine speed, the vehicle speed, and the depression state of the accelerator pedal. That is, this hold mode (HL
In D), the position of the shift lever is drive "D", low "L", or reverse "R", and the engine speed <
The condition of 1000 rpm, the condition of rotation of the clutch output shaft 74 of the hydraulic clutch 50 (vehicle speed) <8 〓 / h, and the driver demand switch 154 as an accelerator pedal switch, which will be described later, are off, that is, the accelerator pedal is not depressed. The judgment is made when the driver satisfies a condition that the driver does not intend to drive the vehicle. In this hold mode (HLD), the clutch pressure (PCLU) of the hydraulic clutch 50 to the clutch hydraulic chamber 58 has a target clutch pressure value (CPSP) of 3.5 〓 / 〓 ² (clutch engagement pressure). As described above, feedback control is performed by the clutch solenoid duty output signal (OPWCLU) to the clutch solenoid valve 106 described later. The clutch solenoid duty output signal is a pulse signal output from the control unit 134 and controls the operation of the clutch solenoid valve 106 by changing the duty ratio.
The hydraulic clutch 50 is controlled in the hold mode (HLD) when the vehicle has no intention of traveling or when it is desired to decelerate during traveling to cut off the engine torque. Further, the clutch pressure of the hydraulic clutch 50 (P
CLU) transmits almost no engine torque, but is maintained at such a low value that the hydraulic clutch 50 is slightly engaged.

The normal start mode (NST) is determined by the position of the shift lever, the engine speed, the vehicle speed, and the depression state of the accelerator pedal. That is, in this normal start mode (NST), the position of the shift lever is drive "D", low "L", or reverse "R", the vehicle speed is <8 〓 / h, and the accelerator pedal is depressed. The driver demand switch 154 is turned on,
It is determined when the condition of engine speed ≧ 1000 rpm is satisfied. In this normal start mode (NST), the clutch pressure (PCLU) corresponding to the engine-generated torque (clutch input torque) is changed to the hydraulic pressure when the hydraulic clutch 50 is re-engaged when the vehicle starts or after the clutch is disengaged. The clutch pressure is applied to the clutch 50, whereby the clutch pressure is maintained at an appropriate value with a quick response in order to prevent the internal combustion engine from rising and to smoothly start the vehicle.

The drive mode (DRV) is determined by the position of the shift lever, the vehicle speed and the clutch slip amount.
That is, in this drive mode (DVR), the shift lever position is set to drive "D", low "L", or reverse "R", vehicle speed ≥8 〓 / h, and clutch slip amount ≤20 rpm. It is judged when the above is satisfied.
In this drive mode (DRV), the vehicle shifts to a complete running state and the hydraulic clutch 50 is completely engaged (clutch lockup state), or when the hydraulic clutch 50 shifts from the normal start mode (NST). Is almost locked up, and when the hydraulic clutch 50 is completely engaged by shifting to the traveling state, a high clutch pressure (maximum clutch pressure) with sufficient margin to withstand the engine torque is applied to the hydraulic clutch 50. It is working.

The continuously variable transmission 2 is shift-controlled by a hydraulic control circuit 76.

The hydraulic pressure control circuit 76 is provided with a line pressure passage 78 for supplying the oil pressure-fed by the oil pump 24 to the driven-side hydraulic chamber 42 to exert a line pressure. One end of the line pressure passage 78 is the oil pump 2
4 is connected to the discharge side, and the other end side is connected to the driven shaft side oil passage 46.

One end of the first oil passage 80 is connected in the middle of the line pressure passage 78. A line pressure control valve 82 is provided on the other end side of the first oil passage 80. The line pressure control valve 82 controls the line pressure in the line pressure passage 78.

The second side of the line pressure control valve 82 has a second
One end side of the oil passage 84 is connected. This second oil passage 84
A line solenoid valve 86 for controlling the operation of the line pressure control valve 82 is provided on the other end side of the.

The oil pump 24 and the first oil passage 80
In the middle of the line pressure passage 78 between the connection parts with
One end side of the oil passage 88 is connected. This third oil passage 88
A ratio pressure control valve 90 is provided on the other end side of the.
One end of a ratio pressure passage 92 is connected to the ratio pressure control valve 90. The other end of the ratio pressure passage 92 is connected to the drive shaft side oil passage 22 of the drive shaft 10.

The ratio pressure control valve 90 is the drive pulley 4
The ratio pressure (primary pressure), which is the hydraulic pressure applied to the drive-side hydraulic chamber 18, is controlled.

A fourth valve is provided on one side of the ratio pressure control valve 90.
One end side of the oil passage 94 is connected. This fourth oil passage 94
A ratio solenoid valve 96 for controlling the operation of the ratio pressure control valve 90 is provided on the other end side of the.

One end of a fifth oil passage 98 is connected to the line pressure passage 78 between the connecting portion of the first oil passage 80 and the driven shaft side oil passage 46. A clutch pressure control valve 100 is provided on the other end side of the fifth oil passage 98.

One end of a clutch pressure passage 102 is connected to the clutch pressure control valve 100. The other end of the clutch pressure passage 102 is connected to the driven shaft clutch oil passage 72 on the hydraulic clutch 50 side.

The clutch pressure control valve 100 controls the clutch pressure, which is the hydraulic pressure applied to the clutch hydraulic chamber 58.

On one side of the clutch pressure control valve 100,
One end side of the sixth oil passage 104 is connected. A clutch solenoid valve 106 that controls the operation of the clutch pressure control valve 100 is provided on the other end side of the sixth oil passage 104.

The seventh oil passage 10 is provided in the middle of the third oil passage 88.
One end side of 8 is connected. One side of the constant pressure control valve 110 is provided on the other end side of the seventh oil passage 108.
This constant pressure control valve 110 is used for line pressure (generally 5 to 25 〓
/ 〓 ² ) is controlled to a constant pressure (4 to 5〓 / 〓 ² ).

To the other side of the constant pressure control valve 110, one end side of the eighth oil passage 112 is connected. This 8th oil passage 11
The other end of 2 is branched into a ninth oil passage 114 and a tenth oil passage 116. The ninth oil passage 114 is connected to the line pressure control valve 8
2 is connected to the other side. The tenth oil passage 116 is connected to the line solenoid valve 86.

In the middle of the eighth oil passage 112, one end side of the eleventh oil passage 118 is connected. This eleventh
The other end of the oil passage 118 is branched into a twelfth oil passage 120 and a thirteenth oil passage 122. The twelfth oil passage 120 is connected to the other side of the ratio pressure control valve 90. 13th oil passage 1
22 is connected to the ratio solenoid valve 96.

Further, one end of a fourteenth oil passage 124 is connected to the middle of the eighth oil passage 112. This 14th
The other end of the oil passage 124 is branched into a fifteenth oil passage 126 and a sixteenth oil passage 128. The fifteenth oil passage 126 is connected to the other side of the clutch pressure control valve 100. The sixteenth oil passage 128 is connected to the clutch solenoid valve 106.

One end of the clutch pressure detection passage 130 is connected to the middle of the clutch pressure passage 102. A hydraulic sensor 132 for detecting the clutch pressure in the clutch pressure passage 102 is provided on the other end side of the clutch pressure detection passage 130.

The line solenoid valve 86, the ratio solenoid valve 96, and the clutch solenoid valve 10
6 and the oil pressure sensor 132 are connected to the control unit 134.

The control unit 134 includes a drive shaft rotation sensor 136 for detecting the rotation of the drive shaft 10 as the engine speed of the internal combustion engine, a driven shaft rotation sensor 138 for detecting the rotation of the driven shaft 34, and a clutch as the vehicle speed. An output shaft rotation sensor 140 that detects the rotation of the output shaft 74 is in communication with the output shaft rotation sensor 140.

The drive shaft rotation sensor 136 detects the rotation of the drive shaft rotation detecting gear 142 fixed to the drive shaft 10 on the rear surface of the drive side housing 20 and outputs a signal corresponding to the rotation of the drive shaft 10 to the control unit. It is output to 134.

The driven shaft rotation sensor 138 detects the rotation of the driven shaft rotation detection gear 144 fixedly mounted on the driven shaft 34 on the rear side of the driven side housing 44 and outputs a signal corresponding to the rotation of the driven shaft 34 to the control section. It is output to 134.

The output shaft rotation sensor 140 is an output shaft rotation detecting gear 146 provided integrally with the clutch output shaft 74.
Is detected and a signal corresponding to the rotation (vehicle speed) of the clutch output shaft 74 is output to the control unit 134.

The control unit 134 also includes a shift lever position detection sensor 148, a carburetor throttle opening sensor 150, a carburetor idle switch 152, a driver demand switch (DDT SW) 154, and a brake switch 156. And the power mode option switch 158.

The shift lever position detection sensor 148 detects the position of the shift lever, that is, the parking "P", the reverse "R", the neutral "N", the drive "D", and the low "L", and outputs the signal. Is output to the control unit 134 to control the line pressure, ratio pressure and clutch pressure required for each shift lever position.

The throttle opening sensor 150 is a throttle opening (TH) of a throttle valve (not shown) of the carburetor.
R) state is detected and a signal corresponding to the throttle opening (THR) is output to the control unit 134, and the control unit 134 detects the engine torque from the memory previously input to the program and the target gear ratio and the target engine speed. Is to determine.

The idle switch 152 sends a signal indicating whether or not the throttle valve is at the idling position to the control section 1.
34, and corrects the value of the throttle opening sensor 150 to more reliably perform the shift control.

The driver demand switch 154 is, for example, an accelerator pedal switch that indicates the driver's willingness to start. The driver demand switch 154 detects whether or not the accelerator pedal is depressed and outputs the signal to the control unit 134. This is to determine the direction of control such as running or starting.

The brake switch 156 detects whether or not the brake pedal is depressed and outputs the signal to the control unit 134, and the control unit 134 causes the hydraulic clutch 5 to operate.
The direction of control such as disconnecting 0 is determined.

Power mode option switch 158
Is used to make the performance of the vehicle sporty or economical, and outputs the signal to the control unit 134 so that the control unit 134 controls the primary pressure and the like.

The control section 134 inputs these various signals, and in this embodiment, the clutch pressure control of the hydraulic clutch 50 is a hold mode (HL) during various control modes.
When the vehicle is started at D), the clutch pressure (PCLU) is temporarily higher than the clutch pressure (PCLU) in the hold mode (HLD) before shifting to the normal start mode (NST) as the start mode. A predetermined amount is increased (height h in FIG. 1), and the clutch pressure of the hydraulic clutch 50 to the clutch hydraulic chamber 58 is controlled in the normal start mode (NST).

Next, a shift control method of the continuously variable transmission 2 will be described with reference to the time chart of FIG.

The hydraulic clutch 50 is creep-controlled when controlled in the hold mode (HLD). In this creep control, the clutch pressure is a clutch pressure target value (C) determined by the engine speed (NE).
PSP).

When the driver intends to start the vehicle during the hold mode (HLD) of the hydraulic clutch 50, that is, when the accelerator pedal is depressed and the throttle opening becomes large, the driver demand switch (DDT) is set.
SW) 154 turns from off to on (position A in FIG. 1). However, immediately, the clutch pressure (PCLU) is first changed to the hold mode (HL) without shifting from the hold mode (HLD) to the normal start mode (NST).
The clutch pressure (MPCLU) is once higher by a predetermined amount (h) than the clutch pressure (HPCLU) at the time of D), and the normal start mode (NST) is set at the B position after a time (t ₁ ) has elapsed from the A position. To do. Then, the clutch starting control is started at the C position after a lapse of time (t ₂ ) from the B position.

Therefore, the normal start mode (NS
At the time of shifting to T), the clutch pressure (PULU) can be increased by a predetermined amount (h) between the creep control and the clutch starting control, so that the clutch starting control can be smoothly shifted to the engine. It is possible to prevent problems such as the engine speed (NE) from rising, falling, and waviness, and to improve the starting feeling by smoothly performing the starting operation.

Then, the normal start mode (NS
When the position T is finished, the hydraulic clutch 5
0 is controlled in the drive mode (DRV).

Next, based on the flowchart of FIG.
A clutch control method of the hydraulic clutch 50 will be described.

In the control section 134, when the program starts (step 202), it is first determined whether the control of the hydraulic clutch 50 is the hold mode (HLD) in the control mode (control mode) (step 2).
04).

In step 204, the hold mode (HL
In the case of D), the driver demand switch (DDT)
It is determined whether the SW) 154 is on or off (step 20).
6).

When the driver demand switch 154 is off in step 206, the clutch pressure target value (CPS) is determined by the first map (PVCRV1) as usual.
P) is determined (step 208) and the process returns (step 210).

On the other hand, when the driver demand switch 154 is turned on in step 206, the clutch pressure target value (CPSP) is determined by the second map (PVCRV2) in this embodiment (step 212).

When the control mode other than the hold mode (HLD) is determined in step 204, another clutch pressure target value (CPSP) is calculated (step 214).

The clutch control method will be described with reference to the control block diagram (closed loop control diagram for hydraulic clutch) of FIG.

The engine speed (NE) is determined by the first map (30
2) and the second map (304) are input in parallel.

When the driver demand switch 154 is turned on and the second map 304 is connected, first, the actual clutch pressure (PCLU) and the clutch pressure target value (CPSP) determined by the second map (304) are added or subtracted. Shi (30
6), the proportional gain (Kp) (3
08) over, the value obtained by multiplying a proportional gain phase advance to the delay processing _{(1 + ST 1/1 +} ST 2) (310)
I do.

Then, this phase lead / lag processing (310)
The value obtained by the above is multiplied by an integral gain (Ki / S), and then the value obtained by multiplying the value from the phase lead / lag process (310) by this integral gain and the clutch solenoid to the clutch solenoid valve 106. Null duty value (NP
C) is added / subtracted (314), and the limiter (316) is applied to the value obtained by this calculation to output the clutch solenoid duty signal (OPWCLU) to the clutch solenoid valve 106, and the clutch solenoid 106
Therefore, the clutch pressure control valve 100 is operated to control the clutch pressure to the clutch hydraulic chamber 58.

As a result, it is possible to mitigate the rapid increase in the clutch pressure target value (CPSP) immediately after shifting to the clutch start control, and to follow the change in the clutch pressure target value (CPSP) to the clutch pressure (PCLU). It is possible to prevent the adverse effect due to the delay, that is, the occurrence of troubles such as the engine speed (NE) rising, dropping, and beating, and to improve the starting feeling by smoothly performing the starting operation.

Further, the control for increasing the clutch pressure (PCLU) by the predetermined amount h higher than that during the creep control in the hold mode (HLD) is when the driver indicates the starting intention, and therefore the clutch pressure (PCLU) is required by the required amount ( Only h) can be increased and startability can be improved.

Further, according to this embodiment, the clutch control of the hydraulic clutch 50 is practical because only the program of the control unit 134 needs to be changed.

[0083]

As is apparent from the above detailed description, according to the present invention, when the starting operation of the vehicle is performed in the hold mode of the clutch pressure control of the hydraulic clutch among various control modes, the start mode is entered. The clutch pressure is temporarily increased by a predetermined amount before the shift of the hold mode before the shift of the, and the clutch pressure of the hydraulic clutch is controlled in the start mode, so that the clutch pressure is increased when the driver indicates the starting intention. It is possible to prevent the occurrence of a trouble at the time of starting operation and improve the starting feeling, by raising the temperature once and then shifting to the start mode to perform the clutch starting control.

Further, according to the clutch control of the present invention,
This is practical because it can be implemented simply by changing the program of the control unit.

[Brief description of drawings]

FIG. 1 is a time chart illustrating a clutch control method for a continuously variable transmission.

FIG. 2 is a flowchart illustrating a clutch control method for a continuously variable transmission.

FIG. 3 is a control block diagram illustrating a clutch control method for a continuously variable transmission.

FIG. 4 is a system configuration diagram of a continuously variable transmission and a hydraulic control circuit.

FIG. 5 is a time chart of a conventional clutch control method.

[Explanation of symbols]

 2 continuously variable transmission 4 drive pulley 6 driven pulley 8 belt 50 hydraulic clutch 78 line pressure passage 82 line pressure control valve 86 line solenoid valve 90 ratio control valve 92 ratio pressure passage 96 ratio solenoid valve 100 clutch pressure control valve 102 clutch pressure oil Road 106 Clutch solenoid valve 134 Control unit 154 Driver demand switch

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[Procedure amendment]

[Submission date] January 14, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

The hold mode is determined by the position of the shift lever, the engine speed, the vehicle speed, and the depression state of the accelerator pedal. That is, in this hold mode, the shift lever position is drive "D", low "L", or reverse "R", engine speed <1000 rpm, and the clutch output shaft of the hydraulic clutch rotates (vehicle speed). ) <8
It is determined when the condition of 〓 / h and the condition that the accelerator pedal switch is off, that is, the accelerator pedal is not depressed and the driver does not intend to drive the vehicle are satisfied. In this hold mode, the clutch pressure of the hydraulic clutch is feedback-controlled by the clutch solenoid duty output signal to the clutch solenoid valve so that the clutch pressure target value will be 4.5〓 / 〓 ² (creep pressure). It The clutch duty output signal is a pulse signal output from the controller, and controls the operation of the clutch solenoid valve by changing the duty ratio.
That is, this hold mode is used when the vehicle has no intention of traveling or when it is desired to decelerate during traveling to cut off the engine torque. Further, the clutch pressure of the hydraulic clutch hardly maintains the engine torque, but is maintained at a low value such that the hydraulic clutch is slightly engaged.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The drive mode is determined by the position of the shift lever, the vehicle speed and the clutch slip amount. That is, in this drive mode, the position of the shift lever is drive "D", low "L", or reverse "R",
Vehicle speed ≧ 8〓 / h and clutch slip amount ≦ 20r
It is judged when pm is satisfied. In this drive mode, the vehicle shifts to the complete running state and the hydraulic clutch is fully engaged (clutch lockup state), or the hydraulic clutch locks up substantially when shifting from the normal start mode. Is in a state of
When the vehicle completely shifts to the traveling state and the hydraulic clutch is completely engaged, a high clutch pressure (pressure equal to the line pressure) with a sufficient margin to withstand the engine torque is applied to the hydraulic clutch.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

[0020]

According to the clutch control method of the present invention, when the starting operation of the vehicle is performed in the hold mode among the various control modes of the clutch pressure control of the hydraulic clutch, the clutch pressure is controlled before shifting to the start mode. The clutch pressure in the hold mode is once increased by a predetermined amount. As a result, when the driver performs a start operation to indicate the intention to start the vehicle, the clutch pressure is temporarily increased by a predetermined amount and then the start mode is entered to perform the clutch start control. It is possible to prevent the occurrence of troubles in the vehicle and improve the starting feeling.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

The hold mode (HLD) is determined by the position of the shift lever, the engine speed, the vehicle speed, and the depression state of the accelerator pedal. That is, this hold mode (HL
In D), the position of the shift lever is drive "D", low "L", or reverse "R", and the engine speed <
The condition of 1000 rpm, the condition of rotation of the clutch output shaft 74 of the hydraulic clutch 50 (vehicle speed) <8 〓 / h, and the driver demand switch 154 as an accelerator pedal switch, which will be described later, are off, that is, the accelerator pedal is not depressed. The judgment is made when the driver satisfies a condition that the driver does not intend to drive the vehicle. In this hold mode (HLD), the clutch pressure (PCLU) to the clutch hydraulic chamber 58 of the hydraulic clutch 50 is such that the clutch pressure target value (CPSP) is 4.5〓 / 〓 ² (creep pressure). And a clutch solenoid duty output signal (OPWCL) to a clutch solenoid valve 106 described later.
Feedback control is performed in U). The clutch solenoid duty output signal is a pulse signal output from the control unit 134 and controls the operation of the clutch solenoid valve 106 by changing the duty ratio. The hold mode (HLD) is used when the vehicle does not have the intention of traveling or when it is desired to decelerate the vehicle during traveling to cut off the engine torque. Further, the clutch pressure (PCLU) of the hydraulic clutch 50 hardly maintains the engine torque, but is maintained at a low value such that the hydraulic clutch 50 is slightly engaged.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

The drive mode (DRV) is determined by the position of the shift lever, the vehicle speed and the clutch slip amount.
That is, in this drive mode (DVR), the shift lever position is set to drive "D", low "L", or reverse "R", vehicle speed ≥8 〓 / h, and clutch slip amount ≤20 rpm. It is judged when the above is satisfied.
In this drive mode (DRV), the vehicle shifts to a complete running state and the hydraulic clutch 50 is completely engaged (clutch lockup state), or when the hydraulic clutch 50 shifts from the normal start mode (NST). Is in a substantially locked state, and when the hydraulic clutch 50 is completely engaged when the hydraulic clutch 50 is completely engaged, a high clutch pressure (pressure equal to the line pressure) with sufficient margin to withstand the engine torque is applied to the hydraulic clutch. 5
It acts on 0.

[Procedure correction 6]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (1)

[Claims] 1. A clutch control method for a continuously variable transmission for a vehicle, wherein a gear ratio is continuously changed by changing a radius of gyration of a belt wound around a driving pulley and a driven pulley. Is provided, and a control unit for inputting various signals to change the clutch pressure to the hydraulic clutch in accordance with the clutch pressure target value is provided, and the clutch pressure control of the hydraulic clutch is performed by this control unit. When the starting operation of the vehicle is performed in the hold mode among the various control modes, the clutch pressure is temporarily made higher than the clutch pressure in the hold mode by a predetermined amount before the shift to the start mode, and the hydraulic pressure is increased. A clutch control method for a continuously variable transmission, characterized in that the clutch pressure of the clutch is controlled in a start mode.