JPH01119432A - Method of controlling clutch for continuously variable transmission - Google Patents

Abstract

PURPOSE:To reduce shocks upon change-over of control mode by changing over the control mode from a drive mode into a normal start mode so as to control a clutch slip when the clutch pressure of a hydraulic clutch is shifted from the drive mode to a hold mode. CONSTITUTION:A control section 90 for changing the duty rate to control speed change in accordance with various inputted conditions such as a throttled opening degree, an engine rotational speed and the like, controls the opening and closing operation of a first primary pressure control three-way solenoid valve 52, a constant pressure control valve 48, a second line pressure control three-way solenoid valve 60 and a third clutch pressure control three-way solenoid valve 68. The control section 90 changes over a hydraulic clutch 74 into a normal start mode so as to control clutch slip of the hydraulic clutch 74 in a specified operating condition, such as that an accelerator pedal signal is turned ON, during the hydraulic clutch 74 being shifted from a drive mode into a hold mode.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a clutch control method for a continuously variable transmission,
In particular, the present invention relates to a clutch control method for a continuously variable transmission that prevents a sudden drop in clutch pressure during low-speed running on an uphill slope, reduces shock when switching control modes, and improves restartability.

[Conventional technology]

In a vehicle, a transmission is interposed between an internal combustion engine and drive wheels. This transmission changes the driving force and running speed of the drive wheels in accordance with the widely varying running conditions of the vehicle, thereby making full use of the performance of the internal combustion engine. The transmission includes, for example, a fixed pulley part fixed to a rotating shaft and a movable pulley part attached to the rotating shaft so as to be able to approach and separate from the fixed pulley part. By decreasing or increasing the groove width using hydraulic pressure, the rotation radius of the belt wrapped around the pulley is decreased or increased, power is transmitted, and the gear ratio (
There is a continuously variable transmission that changes the belt ratio. As this continuously variable transmission, for example, Japanese Patent Application Laid-Open No. 57-18665
Publication No. 6, JP-A-59-43249, JP-A-59-Sho.
It is disclosed in Japanese Patent Application Laid-open No. 77159 and Japanese Patent Application Laid-Open No. 61-233256.

Further, some continuously variable transmissions have a hydraulic clutch that connects and disconnects power using hydraulic pressure. This hydraulic clutch is controlled in various control modes based on signals such as engine speed and carburetor throttle valve opening.

[Problem that the invention seeks to solve]

By the way, in the conventional clutch pressure control method for the hydraulic clutch, when driving at low speed on an uphill slope, that is, when the throttle is depressed by 2 to 3% and the accelerator pedal signal is turned on, only the engine speed or vehicle speed is controlled. Depending on the judgment, it was shifted from drive mode to hold mode.

As a result, the clutch pressure of the hydraulic clutch is suddenly reduced, and the hydraulic clutch is not connected smoothly when changing the control mode, causing a large shock and causing the engine speed to jump when changing the mode. It's inconvenient.

Further, by shifting from the drive mode to the hold mode while running at low speed on an uphill slope, restartability is reduced, which is disadvantageous in practical terms.

[Purpose of the invention]

Therefore, the purpose of this invention is to eliminate the above-mentioned disadvantages.
In a continuously variable transmission control method, a hydraulic clutch whose engagement is controlled by various control modes is provided, and when this hydraulic clutch shifts from a drive mode to a hold mode, the hydraulic clutch is switched to a normal start mode in a specific operating state. By controlling the clutch slip of the hydraulic clutch, it is possible to reliably prevent a sudden drop in clutch pressure during low-speed driving on an uphill slope, reduce shock when switching to control mode, and reduce engine pressure when switching to control mode. To provide a clutch control method for a continuously variable transmission capable of preventing rotational speed up and improving restartability.

[Means for solving problems]

In order to achieve this object, the present invention hydraulically reduces or increases the groove width between the fixed pulley part and the 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 control method that performs speed change control to change the gear ratio by decreasing or increasing the rotation radius of a belt wrapped around both pulleys, a hydraulic clutch whose engagement is controlled by various control modes is provided, and this hydraulic clutch controls the drive. The present invention is characterized in that the hydraulic clutch is switched to a normal start mode in a specific operating state when shifting from the mode to the hold mode, and the clutch slip of the hydraulic clutch is controlled.

[Effect]

According to the method of the present invention, when the clutch pressure of the hydraulic clutch shifts from the drive mode to the hold mode, if a specific operating state is entered, the drive mode is switched to the normal start mode, and the clutch slip of the hydraulic clutch is prevented. Control.

This prevents a sudden drop in clutch pressure during low-speed driving on an uphill slope, reduces shock when switching control modes, prevents engine speed from rising when switching to control mode, and improves restartability. is improving.

〔Example〕

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

1 to 3 show embodiments of this invention. In Figure 2.3, 2 is a continuously variable transmission, 4 is a belt,
6 is a driving side pulley, 8 is a driving side fixed pulley part, 10 is a driving side movable pulley part, 12 is a driven side pulley, 14 is a driven side fixed pulley part, 16 is a driven side movable pulley part It's a piece. The drive-side pulley 6 includes a drive-side fixed pulley piece 10 fixed to the rotating shaft 18, as shown in FIG. 2.3.
and a drive-side movable pulley piece 10 mounted on the rotating shaft 18 so as to be movable in the axial direction of the rotating shaft 18 but not rotatable. Further, the driven side pulley 12 has the same configuration as the driving side pulley 6, and the driven side fixed pulley part 1
4 and a driven side movable pulley piece 16.

First and second housings 20.22 are attached to the driving side movable pulley piece 10 and the driven side movable pulley piece 12, respectively, and first and second hydraulic chambers 24.26 are formed, respectively. . A pressing spring 28 is provided in the second hydraulic chamber 26 on the driven side to urge the driven movable bobbin piece 16 to approach the fixed pulley piece 14 on the driven side.

An oil pump 30 is provided at the end of the rotating wheel 18. This oil pump 30 supplies oil from an oil pan 32 through an oil filter 34 to a hydraulic circuit 36.
The first and second oil passages 38.40 constitute the first and second oil passages 38,40. This is to feed the second hydraulic chamber 24,26.

In the middle of the first oil passage 38, a primary pressure control valve 44, which is a speed change control valve that constitutes the pressure control means 42, is interposed to control the primary pressure, which is the input shaft sheave pressure.

Also, the oil pump 30
The first oil passage 38 on the side is supplied with line pressure (generally 5 to 25 m/c11) at a constant pressure (
1.5~2. Constant pressure control valve 4 that controls the pressure to 0 kg/ci)
8 are arranged in succession. Furthermore, the primary pressure control valve 44 includes:
The first for primary pressure control via the fourth oil passage 50
A three-way solenoid valve 52 is provided in series.

Furthermore, a line pressure control valve 54 having a relief valve function for controlling line pressure, which is pump pressure, is connected to the second oil passage 40 via a fifth oil passage 56 . The line pressure control valve 54 is connected to a second three-way solenoid valve 60 for line pressure control via a sixth oil passage 58 .

Further, a clutch pressure control valve 62 for controlling clutch pressure is connected to the second oil passage 40 on the second hydraulic chamber 26 side via a seventh oil passage 64 than the part communicating with the line pressure control valve 54 . It is set up. This clutch pressure control valve 6
2 is connected to a third three-way solenoid valve 68 for clutch pressure control via an eighth oil passage 66.

Also, the primary pressure control valve 44, the first solenoid valve 52 for primary pressure control, the constant pressure control valve 48, the sixth oil passage 58, the second three-way solenoid valve 60 for line pressure control. The clutch pressure control valves 62 are communicated with each other through a ninth oil passage 70.

The clutch pressure control valve 62 communicates with a hydraulic clutch 74 via a tenth oil passage 72, and also communicates with a hydraulic clutch 74 via a tenth oil passage 72.
A pressure sensor 78 is connected to the middle of the 0 oil passage 70 via an 11th oil passage 76. This pressure sensor 78
can directly detect the oil pressure when controlling the clutch pressure in hold and start modes, etc., and has a function to command the detected oil pressure as the target clutch pressure.In addition, in the drive mode, the clutch pressure is set to the line pressure. Since it is approximately equal to , it also contributes to line pressure control.

The hydraulic clutch 74 includes a piston 80, an annular spring 82, a first pressure coupler 84, a friction plate 86, a second pressure coupler 88, and the like.

In addition, a control section 90 is provided which inputs various conditions such as the throttle opening degree and engine rotation of a carburetor (not shown) of the vehicle, changes the duty rate, and performs gear change control. Solenoid valve 52, constant pressure control valve 48, second three-way solenoid valve 6 for line pressure control
0, and is configured to control the opening/closing operation of the third three-way solenoid valve 68 for clutch pressure control, and also to control the pressure sensor 78. In addition, the various signals input to the control section 90 and the functions of the input signals are as follows: (1) Shift lever position detection signal... Each range such as P, R, N, D, L, etc. Line pressure and ratio required for each range, clutch control■, carburetor throttle opening detection signal...
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 control method 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 method 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).

When the hydraulic clutch 74 shifts from the drive mode to the hold mode, the control unit 90 switches the hydraulic clutch 74 to a normal start mode in a specific driving state, for example, a state where the accelerator pedal signal is ON. It has a function to control clutch slip.

Further, an input shaft rotation detection gear 102 is provided on the outside of the first housing 20, and a first rotation detector 104 on the input shaft side is provided near the outer periphery of the input shaft rotation detection gear 102. Further, an output shaft rotation detection gear 106 is provided outside the second housing 22, and a second rotation detector 1 on the output shaft side is provided near the outer circumference of the output shaft rotation detection gear 106.
08 is provided. Detection signals from the first rotation detector 104 and the second rotation detector 108 are output to the control section 90 and are used to determine the belt ratio of the engine rotation speed.

The hydraulic clutch 74 is provided with an output transmission gear 110, and a third rotation detector 112 for detecting the rotation of the final output shaft is provided near the outer periphery of the output transmission gear 110. In other words, the third rotation detector 112 detects the rotation of the final output shaft directly connected to the reduction gear, the differential, the drive shaft, and the tires, and is capable of detecting the vehicle speed.

Further, the second rotation detector 108 and the third rotation detector 11
2, it is possible to detect the rotation before and after the hydraulic clutch 74, and the amount of clutch slip can be detected.

Next, the operation of this embodiment will be explained.

As shown in FIG. 2, in the continuously variable transmission 2, an oil pump 30 located on a rotating shaft 18 operates according to the drive of the rotating shaft 18, and the oil is pumped from an oil pan 32 at the bottom of the transmission to an oil filter 34. absorbed through. The line pressure, which is this pump pressure, is controlled by the line pressure control valve 54, and if the amount of leakage from the line pressure control valve 54, that is, the amount of relief from the line pressure control valve 54 is large, the line pressure will be low; If it is less, the line pressure will be higher.

The operation of the line pressure control valve 54 is controlled by a dedicated second three-way solenoid valve 60, and the line pressure control valve 54 operates in accordance with the operation of the second three-way solenoid valve 60. , the second three-way solenoid valve 60 is controlled at a duty rate of a constant frequency. That is, the duty rate θ% is a state in which the second three-way solenoid valve 60 does not operate at all, the output side is connected to the atmosphere side, and the output oil pressure is zero. Further, when the duty rate is 100%, the second three-way solenoid valve 60 operates and the output side is connected to the atmosphere side, and the maximum output oil pressure is the same as the control pressure, and the output oil pressure is varied depending on the duty rate. Therefore, the characteristics of the second three-way solenoid valve 60 enable the line pressure control valve 54 to be operated in an analog manner, and the duty rate of the second three-way solenoid valve 60 can be arbitrarily changed to control the line pressure. be able to. Further, the operation of the second three-way solenoid valve 60 is controlled by the control section 90.

The primary pressure for speed change control is controlled by the primary pressure control valve 4.
Similarly to the line pressure control valve 54, the operation of the primary pressure control valve 44 is also controlled by a dedicated first three-way solenoid valve 52. This first three-way solenoid valve 52 is used to conduct the primary pressure to the line pressure or to conduct the primary pressure to the atmosphere side,
The belt ratio is caused to shift to the full overdrive side by conducting to the line pressure, or to the full low side by conducting to the atmosphere side.

The clutch pressure control valve 62 that controls the clutch pressure is connected to the line pressure when the maximum clutch pressure is required, and connected to the atmosphere side when the minimum clutch pressure is required. As with the line pressure control valve 54 and the primary pressure control valve 44, the operation of this clutch pressure control valve 62 is also controlled by a dedicated third three-way solenoid valve 68, so a description thereof will be omitted here. Clutch pressure varies within a range from minimum atmospheric pressure (zero) to maximum line pressure.

There are five patterns for clutch pressure control.

This pattern is as follows: (1) Neutral mode: When the shift position is N or P and the clutch is completely disengaged, 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: When starting or when trying to re-engage the clutch after the clutch has been disengaged, the clutch pressure is adjusted to prevent the engine from revving up and to maintain engine-generated torque (clutch input) that allows the vehicle to operate smoothly. appropriate level (4) according to the torque), special start mode... (a), when the shift lever is repeatedly used in D - N - D at a vehicle speed of 8 km/H or higher, or ( b), 3km/H < vehicle speed < 15km/H during deceleration driving
When the brake state is released in (5), drive mode...... When the clutch is fully engaged after transitioning to full driving state, the clutch pressure is high enough to withstand the engine torque. There are five levels. (1) of this pattern is performed by a dedicated switching valve (not shown) that is linked to the shift investigation, and the other (2)
), (3), (4), and (5) are the first,
This is performed by duty rate control of the second and third three-way solenoid valves 52, 60, 6B. Particularly in the state (5), the clutch pressure control valve 62 controls the seventh oil passage 64.
The clutch pressure and the tenth oil passage 72 are communicated with each other to generate a maximum pressure, and the clutch pressure becomes the same as the line pressure.

In addition, the primary pressure control valve 44 and the line pressure control valve 5
4, and the clutch pressure control valve 62 has first, second, and third clutch pressure control valves.
They are each controlled by the output oil pressure from the three-way solenoid valves 52, 60, 68, and the control oil pressure that controls these first, second, and third three-way solenoid valves 52, 60, 68 is adjusted by the constant pressure control valve 48. constant oil pressure. This control oil pressure is always lower than the line pressure, but it is a stable and constant pressure. Control hydraulic pressure is also introduced into each control valve 44.54.62.
54.62 is being stabilized.

Next, electronic control of the continuously variable transmission 2 will be explained.

Continuously variable transmission 2 is hydraulically controlled, and controls appropriate line pressure for belt retention and torque transmission, primary pressure for changing the gear ratio, and hydraulic clutch 74 according to commands from control unit 90. Clutch pressure for reliable engagement is ensured in each case.

Next, the clutch control mode of the hydraulic clutch will be explained based on the flowchart of FIG.

When the program starts, it is first determined whether the shift lever is in the N range or the P range (step 201).

Step 2 when the shift lever is in N or P range
If 01 is YES, the neutral mode flag is set in step 2.2, and then step 203
to perform neutral mode processing. In this case, the clutch pressure to the hydraulic clutch 74 is Opupil/-.

On the other hand, in step 201, if the shift lever is in a position other than the N or P range and the answer is No, the process proceeds to step 204.

In this step 204, it is determined whether the mode is neutral mode or not. Step 20 in neutral mode
If 4 is YES, a hold mode flag is set in step 205, and hold mode processing is performed in step 206. In this case, hydraulic clutch 7
The clutch pressure to No. 4 is about 3.5 kg/-.

On the other hand, in step 204, if the mode is other than the dual-tral mode, the process proceeds to step 207. In this step 207, it is determined whether or not the hold mode is set. Then, in the hold mode, step 207 is Y.
In the case of ES, it is determined in step 208 whether an accelerator pedal signal for detecting an acceleration operation is ON.

If the accelerator pedal signal is OFF and step 208 is NO, then in step 209 it is determined whether the brake signal is ON.

If the brake signal is ON and step 209 is YES, the process returns to step 206 to perform hold mode processing. Also, if the brake signal is OFF, step 20
If 9 is NO, step 210 determines the vehicle speed or 8 km/h.
Have them judge whether it is less than H or more than 81ua/H. In this step 210, if the vehicle speed≦8 km/H,
As described above, the process returns to step 206 to perform hold mode control.

Further, in step 210, if the vehicle speed is > 3 km/H, the process proceeds to step 215, which will be described later, to set a special start mode flag (indicated by the symbol ■), and in step 216, the accelerator pedal signal is
Have the user make a decision as to whether the answer is N or not. If the determination in step 216 is YES, special start mode processing A is performed in step 217, and if NO, special start mode processing B is performed in step 218.

In step 208, the accelerator pedal signal is
If YES in N, it is determined in step 211 whether the engine speed NE is less than 120 rpm or more than 1200 rpm. In this step 211, NE≧120
In the case of 0rpn+, in step 212, the vehicle speed is 8km.
Have the students judge whether it is less than /H or more than 81am/H.

In step 212, if the vehicle speed≦8km/H,
In step 213, a normal start mode flag is set, and in step 214, normal start mode processing is performed.

Further, in step 211, engine speed NE<
In the case of 120 Orpm, the process returns to step 205 (indicated by the symbol ■), a hold mode flag is set, and hold mode processing is performed in step 206.

Furthermore, in step 212, if the vehicle speed is >3 km/l, a special start mode flag is set in step 215, and it is determined in step 216 whether or not the accelerator pedal signal is ON. If the determination is YES, special start mode processing A is performed in step 217, and if NO, special start mode processing B is performed in step 218.

On the other hand, in the case where the hold mode is not set and the answer is No in step 207, the process proceeds to step 219. In step 219, it is determined whether the mode is normal start mode. If step 219 is YES in the normal start mode, it is determined in step 220 whether or not the accelerator pedal signal is ON. If the accelerator pedal signal is OFF and step 220 is NO, the process returns to step 205 (indicated by the symbol ■). In step 205, a hold mode flag is set, and in step 206, hold mode processing is performed.

Also, if the accelerator pedal signal is ON, step 220 is Y.
In the case of ES, in step 221 the engine speed NE
is less than 50 rpm or more than 500 rpm. In this step 221, engine speed NE≦
In the case of 500 rpm+m, the process returns to step 205 (indicated by the symbol ■), a hold mode flag is set in step 205, and hold mode processing is performed up to step 206.

In addition, if the engine speed NE>50Orpm,
At step 222, the engine speed NE is 120Orpm.
Let them judge whether it is less than 1200 rpm or more than 1200 rpm. Step 2
If the engine rotation speed NE<120Orpm in step 22, the process returns to step 213 and the process proceeds to step 21.
In step 3, normal start mode plug setting is performed, and in step 214, normal start mode processing is performed.

Further, in step 222, the engine speed NE≧1
In the case of 20 Orpm, in step 223, the vehicle speed or 13
Have the students judge whether it is less than km/h or more than 8 km/h.

If the vehicle speed is 8-/H in step 223, the process returns to step 213, where normal start mode control is performed, and in step 214, normal start mode processing is performed.

In step 223, if the vehicle speed is >9 km/)I, in step 224 the clutch slip is set to 20 rpm.
Let them judge whether the speed is less than m or more than 20 rpm.

In step 224, the clutch slip>20 rpm
In the case of s+, the process returns to step 214 and normal start mode processing is performed. Further, in step 224, if clutch slip≦20rp-, a drive mode flag is set in step 229, which will be described later, and drive mode processing is performed in step 230.

On the other hand, if the normal start mode is not selected in step 219 (NO, the process proceeds to step 225. In this step 225, it is determined whether or not the special start mode is selected. In this step 225, it is determined whether the special start mode is selected. If YES,
In step 226, it is determined whether the vehicle speed is 6 km/h or more. In this step 226, if the vehicle speed≦6 kat/H, the process returns to step 205 (indicated by the symbol ■)
In step 205, a hold mode flag is set, and in step 206, hold mode processing is performed.

Further, in step 226, vehicle speed>6 km/
In the case of H, it is determined in step 227 whether the engine speed NE is less than 600 rpm+ or more than 600 rpm. In this step 227, engine speed NE≦6
In the case of 0 Orpm, the process returns to step 205 (indicated by the symbol ■), a hold mode flag is set in step 205, and hold mode processing is performed in step 206.

In step 227, engine speed NE>6
If the clutch slip is 0 Orpm, it is determined in step 228 whether the clutch slip is 2 Orpm or more or less than 20 rpm. In this step 228, clutch slip>
In the case of 2 Orpm, the process returns to step 216 and a determination is made as to whether or not the accelerator pedal signal is ON.

In step 228, clutch slip≦2O
In the case of rpm+, a drive mode flag is set in step 229, and drive mode processing is performed in step 230.

On the other hand, if the answer at step 225 is No, rather than the special mode, the process proceeds to step 231.

In this step 231, it is determined whether the drive mode is indicated. Step 231 instead of drive mode
If No, return to step 205 with code ■
), a hold mode flag is set in step 205, and hold mode processing is performed in step 206. If step 231 is YES under drive mode, step 232 determines the engine speed N.
Have the driver judge whether E is less than 800 rpm+w or more than 800 rpm.

In step 232, engine speed NE<80Or
pm, the process moves to step 233, where it is determined whether the accelerator pedal signal is ON or not. If the determination is NO, the process returns to step 205 (indicated by the symbol ■), and in this step 205, the hold mode is set. A flag is set, and hold mode control is performed in step 206.

If the determination in step 233 is YES, the process returns to step 213 (indicated by the symbol ■), the normal start mode flag is set in step 213, and the normal start mode process is performed in step 214.

In step 232, engine speed NE≧80
In the case of 0rpa+, in step 234, the vehicle speed is changed to 5km.
Have the students decide whether the speed is less than /H or more than 5km/H.

In step 234, if the vehicle speed is <5 h/h, the process moves to step 233, where it is determined whether the accelerator pedal signal is ON or not. If the determination is NO, the process returns to step 205, which is indicated by the symbol ■. ), the hold mode flag is set in step 205, and step 2
Hold mode processing is performed in step 06. Furthermore, if the determination in step 233 is YES, step 2
In step 213, a normal start mode flag is set, and in step 214, normal start mode processing is performed.

If the vehicle speed is greater than or equal to 5 km/H in step 234, it is determined in step 235 whether the brake signal is ON.

In this step 235, the brake signal is OFF and N
In the case of O, drive mode processing is performed in step 230.

Also, in step 235, the brake signal is ON and Y.
In the case of ES, it is determined in step 236 whether or not the accelerator pedal signal is ON. If the accelerator pedal signal is ON and the answer is YES in step 236, drive mode processing is performed in step 230 in the same manner as described above.

If the accelerator pedal signal is OFF and the answer is No in step 236, it is determined in step 237 whether the shift lever position is in the L range.

In step 237, the shift lever is in the L range.
In the case of S, drive mode processing is performed in step 230.

Furthermore, if the shift lever is not in the L range in step 237, that is, in the D or R range, then in step 238 the vehicle speed is 15 km/h or higher or 1
Have the child judge whether the speed is less than 5km/H.

In step 238, if vehicle speed≧15+n/H, drive mode processing is performed in step 230. Further, in step 238, if the vehicle speed is <15 km/H
In this case, the process returns to step 205 (indicated by the symbol ■), the hold mode flag is set in step 205, and the hold mode process is performed in step 206.

As a result, when the hydraulic clutch 74 shifts from the drive mode to the hold mode, in a specific driving state, for example, when the accelerator pedal signal is ON, the hydraulic clutch 74 is switched to the normal start mode, and the hydraulic clutch 74 is switched to the normal start mode. It is possible to control the clutch slip of the hydraulic clutch by controlling the clutch pressure in the normal start mode. During this normal start mode control, it is possible to reliably prevent a sudden drop in clutch pressure during low-speed running on an uphill slope, to smoothly connect the hydraulic clutch, and to reduce shock when switching the control mode.

Furthermore, by switching the hydraulic clutch to normal start mode when the accelerator pedal signal is in the ON state when transitioning from drive mode to hold mode, it is possible to prevent the problem of engine speed revving when transitioning to control mode. It is advantageous.

Furthermore, by being able to prevent a sudden drop in clutch pressure, it is possible to easily control the low speed range at the time of restarting, and it is possible to improve restartability.

〔Effect of the invention〕

As is clear from the above detailed description, according to the present invention,
In a continuously variable transmission control method, a hydraulic clutch whose engagement is controlled by various control modes is provided, and when this hydraulic clutch shifts from a drive mode to a hold mode, the hydraulic clutch is switched to a normal start mode in a specific operating state. Since the clutch slip of the hydraulic clutch is controlled, it is possible to reliably prevent a sudden drop in clutch pressure during low-speed driving on an uphill slope, and the hydraulic clutch can be smoothly engaged, reducing shock when switching control modes. It is possible.

Furthermore, it is possible to prevent the problem of the engine speed revving up when shifting to the control mode, thereby improving usability. Furthermore, by being able to prevent a sudden drop in clutch pressure, control in the low speed range at the time of restarting can be easily achieved and restartability can be improved.

[Brief explanation of the drawing]

1 to 3 show embodiments of the present invention, FIG. 1 is a flowchart of a clutch control method, FIG. 2 is a cutaway sectional view of main parts of a continuously variable transmission, and FIG. 3 is a continuously variable transmission and hydraulic pressure. It is a schematic diagram with a circuit. In the figure, 2 is a continuously variable transmission, 4 is a belt, 6 is a driving pulley, 12 is a driven pulley, 18 is a rotating shaft, 3
0 is the oil pump, 38 is the first oil passage, 40 is the second
an oil passage, 42 a pressure control valve means, 44 a primary pressure control valve, 46 a third oil passage, 48 a constant pressure control valve;
50 is the fourth oil passage, 52 is the first oil passage for primary pressure control.
Three-way solenoid valve, 54 is a line pressure control valve, 56 is a fifth oil passage, 58 is a sixth oil passage, 60 is a second three-way solenoid valve for controlling line pressure, 62 is a clutch pressure control valve, 64 is a seventh oil passage , 66 is an eighth oil passage, 68 is a third three-way solenoid valve for clutch pressure control, 70 is a ninth oil passage, 72 is a tenth oil passage, 74 is a hydraulic clutch, 78 is a pressure sensor, and 90 is a control section. be. Patent Applicant Suzuki Motor Co., Ltd. Patent
Applicant: Mitsubishi Electric Co., Ltd. Agent, Patent Attorney Yoshimi Saigo Figure 3 Proceeding Principal Proposal (Spontaneous) January 218, 1985 Commissioner of the Patent Office Kunio Ogawa Tonoki - 1. Patent Application for Indication of Case 1982 -274742 No. 2, Title of the invention Clutch control method for a continuously variable transmission 3, Relationship to the case of the person making the amendment Patent applicant address 300 Takatsuka, Kamimura, Hamana-gun, Shizuoka Prefecture Name Name
(208) Suzuki Motor Co., Ltd. Representative Suzuki
Osamu (1 idiot) 4. Agent Address: 101 03-292-4
411 (Representative) Address Saigo Patent Building, 2-8 Kanda Ogawamachi, Chiyoda-ku, Tokyo Name (8005) Patent Attorney Nishita J! μ Yiji 7, Contents of amendment 1 (1) [Constant pressure (1,5 to 2
．． 0kg/cd) J is constant pressure (4,0~5゜0kg/
ell) Correct to J. (2) Correct "Normal Start Mode Plug Sent" in lines 6 and 7 of page 23 of the specification to "Normal Start Mode Flag Set."

Claims (1)

[Claims] 1. The width of the groove between the fixed pulley piece and the movable pulley piece attached to the fixed pulley piece so as to be removable can be decreased or increased by hydraulic pressure. In a continuously variable transmission control method that performs speed change control to change the gear ratio by decreasing or increasing the rotation radius of a belt that is wrapped around the belt, a hydraulic clutch whose engagement is controlled according to various control modes is provided, and this hydraulic clutch can switch from drive mode to hold mode. 1. A clutch control method for a continuously variable transmission, comprising switching the hydraulic clutch to a normal start mode and controlling clutch slip of the hydraulic clutch in a specific operating state when shifting to a mode. 2. The clutch control method for a continuously variable transmission according to claim 1, wherein the specific operating state is a state in which an accelerator pedal signal is ON when the hydraulic clutch shifts from drive mode to hold mode.