JP2920276B2 - Shift control method for V-belt continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control method for a V-belt type continuously variable transmission.

[0002]

2. Description of the Related Art Conventionally, in a continuously variable transmission of a vehicle shown in FIG. 2, a belt 4 is hung between a driving pulley 2 and a driven pulley 3 of a continuously variable transmission 1. The input shaft 2A of the drive pulley 2 is connected to an output mechanism of an engine (not shown), and the output shaft 3A of the driven pulley 3 is connected to a traveling drive system. Drive pulley 2
Has a movable pulley 5 slidably mounted thereon, and the rotational diameter of the belt 4 varies according to the sliding position of the movable pulley 5. Therefore, the continuously variable transmission 1 is controlled by controlling the sliding position of the movable pulley 5. Shift control is performed.

The movable pulley 5 of the driving pulley 2 is slid by a motor 6. That is, the output gear 7 attached to the output shaft of the motor 6 rotates the intermediate gear 8,
Further, the gear 9 is driven to rotate in order to rotate the gear 10 attached to the end of the shaft 9A. As a result, the slider 11 having the gear meshing with the gear 9 is driven to rotate. A screw is formed on the shaft of the slider 11,
The screw moves the slider 11 in the axial direction of the driving pulley. Thereby, the slider 11 and the bearing 11
The connected movable pulley 5 is slid along the input shaft 2A via A.

A position sensor 12 for detecting a sliding position of the movable pulley 5 is connected to a slider 11 that meshes with the gear 9. This position sensor 12
Is configured such that the internal resistance changes with the movement of the slider 11, and as a result, a voltage signal corresponding to the sliding position of the movable pulley 5 connected via the slider 11 and the bearing 11A is generated. Output.

A rotation sensor 13 is provided on the outer periphery of the input shaft 2A, and outputs a signal corresponding to the rotation speed of the input shaft 2A. A rotation sensor 14 is provided on the outer periphery of the output shaft 3A, and outputs a signal corresponding to the rotation speed of the output shaft 3A.

The position sensor 12 and the rotation sensors 13 and 14 are connected to a control circuit 15. A microcomputer incorporated in the control circuit 15 receives a signal from the position sensor 12 to operate the movable pulley 5. The sliding position can be recognized, and by inputting signals from the rotation sensors 13 and 14, the actual gear ratio can be calculated. The control circuit 15 is connected to a motor drive circuit 16 that supplies a drive current to the motor 6, and sends a control signal to the motor drive circuit 16 to slide the movable pulley 5 to a target position. Output. When the control signal is input, the motor drive circuit 16 drives the motor 6 to slide the movable pulley 5 to a target position.

[0007] The memory of the microcomputer built in the control circuit 15 stores a three-dimensional map showing the relationship among the throttle opening, the vehicle speed, and the target ratio stepwise as shown in FIG. Therefore, the control circuit 15 includes
In addition to the signals from the position sensor 12 and the rotation sensors 13 and 14, a throttle opening signal from a throttle opening sensor and a vehicle speed signal from a vehicle speed sensor are input.

In the V-belt type continuously variable transmission having the above-described structure, when the vehicle is decelerated and then decelerated to re-accelerate, the control circuit 15 once controls the vehicle so that an appropriate acceleration force is obtained. Low speed ratio of continuously variable transmission
It is controlled to return to the side (shift down). However, when the downshift speed is high, the movable pulley 5 moves quickly to the left side in FIG.
Slips temporarily with respect to the movable pulley 5, especially when the holding force between the pulley and the belt 4 is reduced due to deterioration with time of the belt 4 or the like, in particular, slip occurs, and the belt and the pulley are held again. There is a problem that the slip stops when the force is recovered, and a shock occurs in the vehicle at the moment when the slip stops.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned conventional problems, and has as its object to provide a shift control method capable of preventing a belt from slipping during downshifting during re-acceleration. The gist has a driving pulley attached to an input shaft driven by an engine, a driven pulley attached to an output shaft, and a V belt wound around the driving pulley and the driven pulley. ,
A pulley interval of at least one of the driving pulley and the driven pulley is configured to be variable according to a vehicle speed and an accelerator opening (throttle opening) via a motor by a control circuit. In a V-belt continuously variable transmission configured to perform control to return the gear ratio to a low side (larger gear ratio side) once the vehicle speed is re-accelerated by stepping on the control circuit, the control circuit determines that the vehicle speed is lower than a predetermined value. When it is high, control to temporarily stop the pulley movement to the Low side during the re-acceleration is performed.

[0010]

When the vehicle is decelerated and re-accelerated by depressing the accelerator while the vehicle speed is high, the speed ratio of the continuously variable transmission is once shifted down to the low side via the control circuit. By temporarily stopping the movement of the pulley, a proper holding force between the pulley and the belt can be obtained, and the belt can be prevented from slipping.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. In the control circuit 15 of the continuously variable transmission shown in FIG. 2, when the driver depresses the accelerator and reaccelerates after the vehicle has decelerated, the speed ratio of the continuously variable transmission is temporarily set to Low.
Side, and it is programmed to shift down. By this shift down, an acceleration force is obtained at the time of re-acceleration. At the time of shift down, the movable pulley 5 in FIG. Although it is moved along 2A, when the vehicle speed is high, the control circuit 15 is configured to perform control as shown in the flowchart of FIG. 1 in this example.

That is, in the flowchart of FIG.
In step S1, it is determined whether the vehicle speed is higher than a predetermined value. For example, a value of 5 to 10 km / H is set as the predetermined value. That is, since the shift-down speed is slow at a vehicle speed lower than this, the slip of the belt 4 does not occur. The control circuit 15 performs normal shift control according to the three-dimensional map of FIG. 3 according to the vehicle speed.

Next, in step S2, it is determined whether or not the control operation is being performed. The initial time is N0, and it is determined in step S3 whether the accelerator has been turned on from the OFF state. That is, it is determined whether or not the vehicle has changed from decelerating to re-acceleration. If YES, step S4
, A determination time of about 0.2 seconds is counted.
That is, during this time, the continuation of the ON state of the accelerator is confirmed.

Next, in step S5, it is determined whether the pulley ratio (pulley speed ratio) is within the operating range. For example, it is determined whether the pulley ratio is in the range of 1 to 1.5. That is, slipping of the belt 4 is particularly likely to occur within this speed ratio range. Since the slip is unlikely to occur in other ranges, step S1
2 is performed. If the pulley ratio is within the predetermined operating range, it is determined in step S6 whether or not the pulley ratio is higher than the target ratio. Note that the target ratio is picked up from the above-described three-dimensional map based on the vehicle speed and the accelerator opening. In this state, since the continuously variable transmission is decelerating, the target ratio is L
ow side, the actual pulley ratio is Hi
On the ratio side, the result is YES, and it is then determined in step S7 whether the ratio difference and accelerator opening are within the operating range. That is, if there is no difference between the target ratio and the actual ratio, there is no need to move the movable pulley 5 to the left. If the accelerator opening is, for example, 10 degrees or less and the accelerator is not strongly depressed, the movable pulley 5 Moves slowly, the normal control in step S12 is sufficient.
Therefore, in this step S7, for example, it is determined whether or not the ratio difference is 0.03 or more and the accelerator opening is 10 degrees or more.

After checking the operating conditions in steps S5, S6 and S7, if the operating conditions are satisfied, the operation time is counted in step S8. That is, for example,
For about 3 seconds, the movable pulley 5 is on the Low side, that is, in FIG.
Is continued to the left in the figure.

Next, in step S9, it is determined whether or not the accelerator is depressed again. If the accelerator is continuously depressed, it is determined again in step S10 whether or not the pulley ratio is higher than the target ratio. Determine. In step S10, if the actual pulley ratio is higher than the target ratio on the Hi side, step S10 is executed.
At 11, the target ratio is set to the current pulley ratio, whereby the movement of the movable pulley 5 to the Low side is temporarily stopped. Therefore, the movement of the movable pulley 5 to the left in FIG. 2 is temporarily stopped, and the movable pulley 5 does not move to the left at a high speed. Therefore, the belt 4 does not slip with the pulley 5 and has an appropriate holding force. Will be retained.

When the foot is released from the accelerator, or when the actual pulley ratio matches the target ratio, the process returns to the normal control step S12 in steps S9 and S10, and the pulley is temporarily stopped. Thus, the control for preventing the belt 4 from slipping is released. That is, the return to the normal control is performed at the time when the vehicle speed of the vehicle increases, the target ratio gradually changes to the Hi side, and coincides with the ratio of step S11 in which the pulley is temporarily stopped.

As described above, in this embodiment, when the speed ratio is shifted down to the low side when the accelerator is depressed and the vehicle is accelerated again from the deceleration running, the movement of the pulley to the downshift side is temporarily stopped and the belt is stopped. Can be satisfactorily prevented, and the shock of the vehicle that occurs when the belt slips due to abrupt downshifting and stops again as in the prior art can be satisfactorily reduced, especially when the vehicle speed is high. Since the belt slips easily at the time of re-acceleration, the operation at the time of high-speed re-acceleration can be smoothly performed.

[0019]

According to the present invention, a V-belt type continuously variable transmission configured to perform control to return the gear ratio to a low side (larger gear ratio side) when the accelerator is depressed and the vehicle is reaccelerated from deceleration traveling. The control circuit performs control to temporarily stop the pulley movement to the Low side at the time of the re-acceleration when the vehicle speed is higher than a predetermined value, so that the accelerator pedal is conventionally depressed at a high vehicle speed. When the vehicle accelerated again, the belt slipped and shocked the vehicle.However, the sudden downshift of the pulley was temporarily stopped, and the holding force of the belt against the pulley was secured.
This has the effect that the slip of the belt is well prevented and smooth operation can be realized at the time of re-acceleration at high speed.

[Brief description of the drawings]

FIG. 1 is a flowchart of a shift control of the present embodiment.

FIG. 2 is an explanatory diagram of a control configuration of a continuously variable transmission of a vehicle.

FIG. 3 is a three-dimensional map showing a relationship between a throttle opening, a vehicle speed, and a target ratio in a stepwise manner.

[Explanation of symbols]

 Reference Signs List 1 continuously variable transmission 2 drive pulley 3 driven pulley 4 belt 5 movable pulley 6 motor 9 gear 11 slider 12 position sensor 13 rotation sensor 14 rotation sensor 15 control circuit 16 motor drive circuit

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (1)

(57) [Claims] A driving pulley attached to an input shaft driven by an engine; a driven pulley attached to an output shaft; and a V belt wound around the driving pulley and the driven pulley. A pulley interval of at least one of the driving pulley and the driven pulley is configured to be variable according to a vehicle speed and an accelerator opening (throttle opening) via a motor by a control circuit. In a V-belt continuously variable transmission configured to perform control to return the gear ratio to a low side (larger gear ratio side) once the vehicle speed is re-accelerated by stepping on the control circuit, the control circuit determines that the vehicle speed is lower than a predetermined value. A shift control method for a V-belt type continuously variable transmission, wherein a control is performed to temporarily stop the pulley movement to the Low side during the re-acceleration when the speed is high Law.