JPH0739256B2 - Clutch pressure control method for continuously variable transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch pressure control method for a continuously variable transmission, and in particular, delays a start time of clutch pressure control in a start mode by a predetermined time to ensure a sufficient line pressure. The present invention relates to a clutch pressure control method for a continuously variable transmission that secures the above, facilitates control of a hydraulic clutch, prevents fluctuations in the engine speed, and ensures smooth changes in the engine speed.

[Conventional technology]

In a vehicle, a transmission is interposed between an internal combustion engine and driving wheels. This transmission changes the driving force of the driving wheels and the traveling speed in accordance with the traveling condition of the vehicle that changes over a wide range, and thus the performance of the internal combustion engine is fully exhibited. In the transmission, for example, a fixed pulley part fixed to the rotary shaft and a movable pulley part mounted on the rotary shaft so as to be able to come into contact with and separate from the fixed pulley part are formed between both pulley part of the pulley. There is a continuously variable transmission that changes the gear ratio (belt ratio) by increasing / decreasing the radius of gyration of a belt wound around a pulley by transmitting / decreasing a groove width by hydraulic pressure to transmit power. This continuously variable transmission is disclosed, for example, in JP-A-57-186656, JP-A-59-43249, JP-A-59-77159 and JP-A-61-233256.

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

[Problems to be solved by the invention]

By the way, in the conventional clutch pressure control method for the hydraulic clutch, as shown in FIG. 6, the clutch pressure and the line pressure are controlled to the minimum values in the hold mode, and when the hold mode is changed to the start mode, the clutch pressure and the line pressure are controlled. The pressure is controlled, and it takes some time to reach a line pressure sufficient for start control.

At this time, the line pressure fluctuates greatly until the line pressure reaches a pressure sufficient for start control, and this line pressure fluctuation actually appears as a fluctuation of the engine speed. That is, although the clutch pressure may be the same as the line pressure (range A in the start mode of FIG. 6), the clutch pressure does not exceed the line pressure and is applied to the hydraulic clutch. This is because the clutch pressure is the line pressure itself.

Generally, when the line pressure increases rapidly, hunting occurs in the line pressure, and the clutch pressure obtained by dividing the line pressure fluctuates, causing fluctuations in the torque capacity of the hydraulic clutch and fluctuations in the engine load. Fluctuations are caused.

The state of fluctuation of the clutch pressure will be described in detail. When the clutch pressure control of the hydraulic clutch is controlled without delay, as shown in FIG. Although the pressure rises to a level sufficient for start control, in the course of this pressure increase, the increase in line pressure is delayed with respect to the increase in target clutch pressure, and the line pressure does not reach the target clutch pressure. As shown in FIG. 6, the clutch pressure and the line pressure are substantially equal to each other, and are affected by hunting.

As a result, since the engine speed is feedback-controlled in the start mode, the above-mentioned large fluctuation of the engine speed has an influence on the clutch pressure and the engine speed, which deteriorates the feeling of the entire start control. There is an inconvenience to do.

Further, the rise of the line pressure is bad due to the response of the hydraulic circuit, and various problems such as adversely affecting the rise of the line pressure occur.

[Object of the Invention]

Therefore, the object of the present invention is to eliminate the above-mentioned inconveniences.
In the continuously variable shift control method, when the hydraulic clutch shifts from the hold mode in which the line pressure is the minimum value to the start mode in which the line pressure is increased, the start time of the clutch pressure control of the hydraulic clutch in the start mode is delayed by a predetermined time. By preventing the engine speed from fluctuating due to line pressure fluctuations and controlling to ensure a sufficient line pressure in the start mode, the engine speed fluctuations are prevented and smooth changes in engine win points are achieved. (EN) A clutch pressure control method for a continuously variable transmission, which can be ensured and can also ensure a sufficient line pressure without fluctuations, and can easily control the clutch pressure of a hydraulic clutch.

[Means for solving problems]

To achieve this object, the present invention is characterized in that the groove width between the fixed pulley portion piece and the movable pulley portion piece mounted on the fixed pulley portion piece so as to be able to come into contact with and separate from each other is increased by hydraulic pressure to increase the groove width. In the continuously variable transmission control method, the transmission is controlled to decrease the radius of gyration of the belt wound around both pulleys to change the gear ratio and to control the line pressure to the clutch pressure via the clutch pressure control valve. A hydraulic clutch whose discontinuity is controlled by a control mode is provided, and when the hydraulic clutch shifts from a hold mode in which the line pressure is a minimum value to a start mode in which the line pressure is increased, the clutch pressure control of the hydraulic clutch in the start mode is performed. The start time is delayed by a specified amount of time to prevent fluctuations in engine speed due to fluctuations in line pressure, and to enter the start mode. And controlling so as to secure sufficient line pressure that.

[Action]

According to the method of the present invention, when the hydraulic clutch shifts from the hold mode in which the line pressure is the minimum value to the start mode in which the line pressure is increased, the start time of the clutch pressure control of the hydraulic clutch in the start mode is set to a predetermined time. Delay to prevent the engine speed from fluctuating due to line pressure fluctuations, to ensure smooth engine speed changes, and to ensure sufficient line pressure that does not fluctuate, making it easier to control the clutch pressure of the hydraulic clutch. It's done.

〔Example〕

Embodiments of the present invention will be described in detail and specifically below with reference to the drawings.

1 to 5 show an embodiment of the present invention. 4 and 5, 2 is a continuously variable transmission, 4 is a belt,
6 is a drive side pulley, 8 is a drive side fixed pulley part piece, 10 is a drive side movable pulley part piece, 12 is a driven side pulley, 14 is a driven side fixed pulley part piece, 16 is a driven side movable pulley part piece Is. As shown in FIGS. 4 and 5, the drive-side pulley 6 includes a drive-side fixed pulley portion 10 fixed to a rotary shaft 18 and a rotary shaft.
A drive-side movable pulley part (10) mounted on the rotating shaft (18) so as to be movable in the axial direction and non-rotatable. Also,
The driven pulley 12 has the same structure as the driving pulley 6 and includes a driven fixed pulley portion 14 and a driven movable pulley portion 16.

First and second housings 20 and 22 are attached to the driving side movable pulley portion piece 10 and the driven side movable pulley portion piece 12, respectively, and first and second hydraulic chambers 24 and 26 are formed, respectively. It In the second hydraulic chamber 26 on the driven side, the driven side movable pulley part 16
A pressing spring (28) for urging the driven pulley (14) to approach the driven-side fixed pulley section (14) is provided.

An oil pump 30 is provided at the end of the rotary shaft 18. This oil pump 30 pumps oil into an oil pan 32.
The oil is supplied to the first and second hydraulic chambers 24 and 26 through the oil filter 34 and the first and second oil passages 38 and 40 forming the hydraulic circuit 36. In the middle of the first oil passage 38, a primary pressure control valve 44, which is a shift control valve that constitutes pressure control means 42 for controlling the primary pressure that is the input shaft sheave pressure, is provided. Further, the first oil passage 38 of the oil pump 30 side of the primary pressure control valve 44, the line pressure by the third oil passage 46 (typically 5~25kg / cm ²⁾ to a constant pressure (4.0~5.0kg / cm ² ), A constant pressure control valve 48 is connected in series. Further, the primary pressure control valve 44 is provided with a first three-way solenoid valve 52 for primary pressure control via a fourth oil passage 50.
Are lined up.

In the middle of the second oil passage 40, a line pressure control valve 54 having a relief valve function for controlling the line pressure which is a pump pressure.
Are continuously provided via the fifth oil passage 56. The line pressure control valve 54 is provided with a second line pressure control second three-way solenoid valve 60 connected in series through a sixth oil passage 58.

Further, the line pressure control valve 54 has a second position
A clutch pressure control valve 62 for controlling the clutch pressure is connected in the middle of the second oil passage 40 on the hydraulic chamber 26 side via a seventh oil passage 64. The clutch pressure control valve 62 has an eighth
Third three-way solenoid valve for clutch pressure control via oil passage 66
68 are lined up.

Further, 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 and the clutch pressure control valve 62 are in communication with each other through a ninth oil passage 70.

The clutch pressure control valve 62 communicates with the hydraulic clutch 74 via the tenth oil passage 72, and also communicates with the pressure sensor 78 midway through the tenth oil passage 70 via the eleventh oil passage 76. The pressure sensor 78 can directly detect the hydraulic pressure when controlling the clutch pressure in the hold and start modes, and has a function of instructing the detected hydraulic pressure to be the target clutch pressure. Further, since the clutch pressure becomes substantially equal to the line pressure in the drive mode, it also contributes to the line pressure control.

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

Further, there is provided a control unit 90 for changing the duty ratio by inputting various conditions such as a throttle opening of a carburetor (not shown) of the vehicle and engine rotation, and the control unit 90 controls the first primary pressure control first. The three-way solenoid valve 52, the constant pressure control valve 48, the line pressure control second three-way solenoid valve 60, and the clutch pressure control third three-way solenoid valve 68 are controlled to be opened and closed, and the pressure sensor 78 is also controlled. Has been done. Further, the various signals input to the control unit 90 and the functions of the input signals will be described in detail. The detection signal of the shift lever position ... Each range signal such as P, R, N, D, L Required line pressure, ratio, clutch control, carburetor throttle opening detection signal ...... Engine torque is detected from the memory input in the program in advance, target ratio or target engine speed is determined, and carburetor idle position is detected. Signal …… Improves accuracy in correction and control of the caplet throttle opening sensor, accelerator pedal signal …… Detects driver's intention based on accelerator pedal depression state, determines control method during running or starting, brake signal ...... Detects whether or not the brake pedal is depressed, determines the control method such as clutch disengagement, and Mode option signal …… The performance of the vehicle is sports (or economy)
Use as an option for

This control unit 90, as shown in FIG.
When the 74 shifts from the hold mode in which the line pressure is the minimum value to the start mode in which the line pressure is increased, the start time of the clutch pressure control of the hydraulic clutch 74 in the start mode is set to a predetermined time, for example, a delay time counter DELCNT.
It has a function of delaying by the delay time DELCNTI which is the initial value of to prevent the engine speed from fluctuating due to the fluctuation of the line pressure and control to secure a sufficient line pressure in the start mode.

This delay time DELCNTI is the time T _LR until the line pressure sufficient for start control is reached when the hydraulic clutch 74 shifts from the hold mode to the start mode.
It is decided by taking into account the safety factor in (A part of FIG. 6).

Further, the input shaft rotation detection gear is provided outside the first housing 20.
102 is provided, and a first rotation detector 104 on the input shaft side is provided near the outer peripheral portion of the input shaft rotation detection gear 102.
Further, the output shaft rotation detection gear is provided outside the second housing 22.
106 is provided, and a second rotation detector 108 on the output shaft side is provided near the outer peripheral portion of the output shaft rotation detection gear 106. The detection signals of the first rotation detector 104 and the second rotation detector 108 are output to the control unit 90 and are used for grasping the belt ratio of the engine speed.

An output transmission gear 110 is provided in the hydraulic clutch 74,
A third rotation detector 112 for detecting the rotation of the final output shaft is provided near the outer peripheral portion of the output transmission gear 110. In other words, the third rotation detector 112 detects the rotation of the reduction gear, the differential gear, the drive shaft, and the final output shaft directly connected to the tire, and can detect the vehicle speed.
Further, the second rotation detector 108 and the third rotation detector 112 can detect the rotation around the hydraulic clutch 74, and can detect the clutch slip amount.

Next, the operation of this embodiment will be described.

The continuously variable transmission 2 has a rotating shaft 18 as shown in FIGS.
The oil pump 30 located above operates in response to the drive of the rotary shaft 18, and the oil is absorbed from the oil pan 32 at the bottom of the transmission through the oil filter 34. The line pressure, which is the pump pressure, is controlled by the line pressure control valve 54.If the amount of leakage from the line pressure control valve 54, that is, the escape amount of the line pressure control valve 54 is large, the line pressure becomes low, and conversely. If it is small, the line pressure will be high.

The operation of the line pressure control valve 54 is performed by a dedicated second three-way solenoid valve 60.
The line pressure control valve 54 operates following the operation of the second three-way solenoid valve 60, and the second three-way solenoid valve 60 is controlled with a duty ratio of a constant frequency. . That is, the duty ratio of 0% means that the second three-way solenoid valve 60 does not operate at all, the output side is connected to the atmosphere side, and the output hydraulic pressure becomes zero. Also, the duty ratio is 100%
Means that the second three-way solenoid valve 60 operates so that the output side is connected to the atmosphere side, the maximum output hydraulic pressure is the same as the control pressure, and the output hydraulic pressure is varied according to the duty ratio. Therefore, the characteristic of the second three-way solenoid valve 60 is that the line pressure control valve 54 can be operated in an analog manner.
The line pressure can be controlled by arbitrarily changing the duty factor of 60. The operation of the second three-way solenoid valve 60 is controlled by the controller 90.

The primary pressure for shift control is the primary pressure control valve 44
Similarly to the line pressure control valve 54, the operation of the primary pressure control valve 44 is controlled by the dedicated first three-way solenoid valve 52. This first three-way solenoid valve 52
Used to connect the primary pressure to the line pressure or the primary pressure to the atmosphere side. Conduct the line pressure to shift the belt ratio to the full overdrive side, or to the atmosphere side to shift to the full low side. It is what makes me.

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

There are five patterns for controlling the clutch pressure.

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 minimum pressure (zero) (2), Hold mode ...... The shift position is D or R and the throttle When there is no intention to drive by releasing, or when you want to reduce the engine torque by decelerating while driving, the clutch pressure is low enough to contact the clutch (3), the start mode ...... The clutch is re-engaged when starting or after the clutch is disengaged. When connecting the engine, the clutch pressure can be prevented from rising and the vehicle can operate smoothly. An appropriate level according to the engine generated torque (clutch input torque) (4), special start mode ...... (a) , If the vehicle speed is 8km / H or more, shift the shift lever to D → N
→ When repeatedly used with D, or (b), the state where the brake state is released at 8 km / H <vehicle speed <15 km / H during deceleration operation, (5), drive mode …… Transition to complete running state When the clutch is fully engaged, there are five levels of clutch pressure, high enough to withstand the engine torque. (1) of this pattern is performed by a dedicated switching valve (not shown) that is interlocked with the shift operation, and the other (2), (3), (4), and (5) are the first, second, and The duty ratio control of the third three-way solenoid valves 52, 60, 68 is performed. Particularly in the state (5), the clutch pressure control valve 62 causes the seventh oil passage 64 and the
10 The oil pressure is communicated with the oil passage 72, and the maximum pressure is generated, and the clutch pressure becomes the same as the line pressure.

Further, the primary pressure control valve 44 and the line pressure control valve 54,
The clutch pressure control valve 62 is controlled by the output hydraulic pressures from the first, second and third three-way solenoid valves 52, 60 and 68, respectively. These first, second and third three-way solenoid valves 52, 60, 68
The control oil pressure for controlling the is a constant oil pressure adjusted by the constant pressure control valve 48. This control oil pressure is always lower than the line pressure, but is a stable and constant pressure.
The control oil pressure is also introduced into the respective control valves 44, 54, 62 to stabilize these control valves 44, 54, 62.

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

The continuously variable transmission 2 is hydraulically controlled, and in response to a command from the control unit 90, an appropriate line pressure for belt holding and torque transmission, a primary pressure for changing a gear ratio, and a hydraulic clutch 74 are set. The respective clutch pressures for ensuring the engagement are secured.

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

If the program starts (100), it is first judged whether or not it is the start mode (101). If this judgment (101) is NO, the main program (107) is entered, and if YES, the previous time is also started. It is judged whether the mode is the mode (102). If this judgment (102) is NO, the delay time D
ELCNTI is this delay time counter DELCNT (103),
The clutch pressure control (104) immediately before shifting to the start mode is performed, and when the above determination (102) is YES, it is determined (105) whether or not the delay time counter DELCNT is 0. If this determination (105) is YES, the main program (107) described above is entered, and if the determination is NO, the delay time counter D
A new delay counter DELCNT by subtracting 1 from ELCNT
Then (106), the clutch pressure control (104) immediately before shifting to the start mode is performed. Then, the clutch pressure control (1
After 04), transfer to the main program (107).

As a result, when the hydraulic clutch shifts from the hold mode to the start mode, the clutch pressure control in the hold mode is performed only while the delay time has elapsed, and the clutch pressure control in the start mode is performed after the delay time has elapsed. It is possible to prevent the engine speed from fluctuating due to the fluctuation of the line pressure, and to secure a smooth engine speed.

Further, by performing the start control while ensuring a sufficient line pressure after the delay time has elapsed, the hydraulic clutch can be easily controlled, which is practically advantageous.
That is, when the line pressure is sufficiently secured, the clutch pressure has a characteristic that follows the change of the duty of the clutch driving solenoid well, so that if the change amount of the duty is constant, as shown in FIG. The higher the line pressure, the greater the change in clutch pressure, and the above-mentioned control of the hydraulic clutch can be easily performed.

Furthermore, by controlling the clutch pressure in the start mode after the delay time has elapsed, fluctuations in the engine speed do not affect the clutch pressure and engine speed, improving the overall feel of the start control and improving usability. it can.

Furthermore, since it is not necessary to add new hardware and can be dealt with only by changing the software, and most of the conventional programs can be used, the amount of increase in the memory of the control unit can be reduced and the cost can be reduced. Can be prevented from rising, which is economically advantageous.

〔The invention's effect〕

As is apparent from the above detailed description, according to the present invention,
In the continuously variable transmission control method, the start time of the 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 in which the line pressure is the minimum value to the start mode in which the line pressure is increased. The engine speed is prevented from fluctuating due to the fluctuation of the line pressure, and the control is performed to secure a sufficient line pressure in the start mode. Therefore, the fluctuation of the engine rotational speed due to the fluctuation of the line pressure can be prevented, and the smooth engine operation can be prevented. The number of rotations can be secured. Further, by performing the start control while ensuring a sufficient line pressure after the delay time has elapsed, the hydraulic clutch can be easily controlled, which is practically advantageous. Furthermore, by controlling the clutch pressure in the start mode after the delay time has elapsed, fluctuations in the engine speed do not affect the clutch pressure and engine speed, improving the overall feel of the start control and improving usability. It can be done. Furthermore, since it is possible to deal with it only by changing the software without adding new hardware, and most of the conventional programs can be used,
It is possible to prevent the cost from being increased, which is economically advantageous.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a flowchart of a clutch pressure control method, and FIG. 2 is a time chart when shifting from a hold mode to a start mode,
FIG. 3 is a diagram showing a duty characteristic of a clutch pressure solenoid, FIG. 4 is a cutaway sectional view of a main part of a continuously variable transmission, and FIG.
The figure is a schematic diagram of a continuously variable transmission and a hydraulic circuit. FIG. 6 is a time chart when shifting from the hold mode to the start mode, which shows the prior art of the present invention. In the figure, 2 is a continuously variable transmission, 4 is a belt, 6 is a driving side pulley, 12 is a driven side pulley, 18 is a rotating shaft, 30 is an oil pump, 38 is a first oil passage, 40 is a second oil passage. , 42 is a pressure control valve means, 44 is a primary pressure control valve, 46
Is a third oil passage, 48 is a constant pressure control valve, 50 is a fourth oil passage, 52 is a first three-way solenoid valve for primary pressure control, 54 is a line pressure control valve, 56 is a fifth oil passage, and 58 is a sixth oil passage. A passage, 60 is a second three-way solenoid valve for line pressure control, 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 controlling clutch pressure, 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 controller.

 -------------------------------------------------------------------------------------------------------------- ─── Continuation of the front page (72) Inventor Tatsumi Takumi, 840 Chiyoda-cho, Himeji-shi, Hyogo Prefecture Mitsubishi Electric Corporation Himeji Works (72) Inventor Hiroaki Yamamoto 1 at 13 Sadamoto-cho, Himeji-shi, Hyogo Mitsubishi Electric Control Software Himeji Business Co., Ltd.

Claims (1)

[Claims] Claim: What is claimed is: 1. A groove width between the fixed pulley portion piece and a movable pulley portion piece that is attached to the fixed pulley portion piece so as to be able to come into contact with and separated from the fixed pulley portion piece is increased by hydraulic pressure and wound around the both pulleys. In the continuously variable transmission control method that controls the line pressure to be the clutch pressure via the clutch pressure control valve in the continuously variable transmission control method that controls the shift to change the gear ratio by decreasing the radius of gyration of the belt and to change the gear ratio. Is provided, and when the hydraulic clutch shifts from the hold mode in which the line pressure is the minimum value to the start mode in which the line pressure is increased, the start time of the clutch pressure control of the hydraulic clutch in the start mode is set to a predetermined time. Delay to prevent fluctuations in engine speed due to fluctuations in line pressure and ensure sufficient line pressure in the start mode Clutch pressure control method of a continuously variable transmission and to control to.