JPS6239335A - Clutch control method in switchback running for vehicle with automatic transmission - Google Patents

Abstract

PURPOSE:To realize a smooth deceleration, by presetting a negative acceleration to the pressing angle of an accelerator pedal, and controlling a clutch depending on the difference between the preset negative acceleration and the actual negative acceleration, when the automatic transmission is converted from a running direction to the reverse direction. CONSTITUTION:An automatic transmission 3 connected to the engine 1 of a fork lift through a clutch 2 is shifted to the low and the high stages by a shift converting actuator 7, and to the forward, backward, and the neutral stages through a forward/backward shift converting actuator 8. In this case, a negative acceleration to the pressing angle of an accelerator pedal is preset. And, when the automatic transmission 3 is converted from a running direction to the reverse direction, the negative acceleration at the time and the actual negative acceleration are compared, and the connecting condition of the clutch 2 is controlled to make the actual negative acceleration equal to the negative acceleration of the accelerator pedal pressing angle.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a clutch control method during switchback driving of a vehicle equipped with an automatic transmission.

(Conventional technology) In recent years, various vehicles equipped with automatic transmissions have been proposed.

Vehicles equipped with these automatic transmissions are required to be able to perform various types of travel similar to those of conventional manual transmission vehicles.

(Problem to be Solved by the Invention) In the case of switchback driving among various types of driving, in a vehicle with a manual transmission, the traveling direction for deceleration after the manual transmission is switched to the opposite direction to the traveling direction. Energy absorption was done by clutch operation, which relied on the driver's intuition.

And whether it was good or bad depended entirely on the skill of the driver.

The first object of the present invention is to provide an automatic transmission that enables a vehicle equipped with an automatic transmission to perform switchback driving in the same manner as the above-mentioned manual transmission vehicle, and that enables smooth deceleration regardless of the skill of the driver. An object of the present invention is to provide a clutch control method during switchback driving of a vehicle equipped with the following.

Roughly speaking, the second object of the present invention is to provide an automatic transmission which, in addition to the first object, can perform more optimal switchback driving by more finely controlling the deceleration rate according to the load of the vehicle. An object of the present invention is to provide a clutch control method during switchback driving of a vehicle equipped with the present invention.

Structure of the Invention (Means for Solving Problems) In order to achieve the above-mentioned first object, the first invention provides a method for operating a forward/reverse operation lever while the vehicle is traveling to match the current traveling direction. In a driving method for a vehicle equipped with an automatic transmission that performs switchback driving by switching from a direction point to a direction point in the opposite driving direction, a negative acceleration is set in advance with respect to the depression angle of the accelerator pedal, and the automatic transmission When the direction of travel is switched to the opposite direction based on the operation, the negative acceleration with respect to the depression angle of the accelerator pedal at that time is compared with the actual negative acceleration of the vehicle at that time, and the actual negative acceleration is determined from the accelerator pedal. The gist of this invention is to provide a clutch control method during switchback driving of a vehicle equipped with an automatic transmission, which controls the connection state of the clutch so that the acceleration is negative with respect to the depression angle.

In order to achieve the above-mentioned second object, the second invention includes: 1) operating a forward/reverse control lever while driving to switch from a direction point corresponding to the current driving direction to a direction point in the opposite driving direction; In a driving method for a vehicle equipped with an automatic transmission that performs switchback driving, a plurality of negative accelerations are set in advance for different accelerator pedal operation amounts depending on the load of the vehicle, and the automatic transmission When the vehicle is switched to a direction opposite to the traveling direction, the negative acceleration relative to the depression angle of the accelerator pedal in the load state at that time is compared with the actual negative acceleration of the vehicle at that time, and the actual negative acceleration is determined as the load state. The gist of this invention is to provide a clutch control method during switchback driving of a vehicle equipped with an automatic transmission, which controls the connection state of the clutch so that the acceleration is negative relative to the depression angle of the accelerator pedal.

(Operation) In the first invention, when the gear of the automatic transmission is switched in the opposite direction to the traveling direction for switchback driving,
The vehicle is slowed down. This deceleration is achieved by comparing the negative acceleration with respect to the preset accelerator pedal depression angle and the actual negative acceleration of the vehicle at that time, and based on the comparison, the actual negative acceleration is determined as the negative acceleration with respect to the accelerator pedal depression angle. It is controlled by adjusting the engagement state of the clutch so that the acceleration is as follows.

In addition to the effects of the first invention, the second invention further finely controls the degree of deceleration according to the load on the vehicle.

(Example) Hereinafter, an example in which the present invention is embodied in a forklift will be described with reference to the drawings.

Figure 1 shows the mechanism of the drive system of a forklift, in which the output of the engine 1 is transmitted through a dry single-plate clutch 2 to an automatic transmission 3.
The automatic transmission 3 drives the running drive wheels 5 forward and backward at a predetermined gear ratio via the differential gear mechanism 4. The engine 1 is also used as a drive source for a hydraulic pump that supplies hydraulic oil to a lift cylinder for raising and lowering the fork and a tilt cylinder for tilting the mast.

The connection state of the dry single-plate clutch 2 that turns on and off the output of the engine 1 is adjusted relative to the stroke amount of a rod 6a that expands and contracts based on the drive of the clutch control actuator 6. On the other hand, the automatic transmission 3 can shift between 1 (fast, low speed) and 2 (fast, high speed) by driving the shift switching actuator 7, and can shift forward by driving the forward/reverse switching actuator 8; (neutral) and reverse driving.

Next, an electric circuit for driving and controlling each of the actuators 6 to 8 will be explained with reference to FIG. 2.

The vehicle speed sensor 11 detects the rotational speed of the output shaft of the automatic transmission 3, as shown in FIG. 1, and outputs the detection signal to the input/output interface 12. The engine rotation speed sensor 13 detects the rotation speed of the output shaft of the engine 1, as shown in FIG. 1, and outputs the detection signal to the interface 12.

The stroke detection sensor 14 is composed of a potentiometer and detects the stroke amount of the rod 6a of the clutch control actuator 6, and the detection signal is sent to the A/D converter 1.
5, the signal is converted into a digital signal and output to the interface 12.

The pedal operation amount detection sensor 16 is composed of a potentiometer, and detects the depression angle ex of the accelerator pedal 17 provided at the driver's seat, and the detection signal is converted into a digital signal by the A/D converter 18 and sent to the interface 12. is output to.

The forward/reverse motion detection sensor 19 detects the switching state of the forward/reverse motion control lever 20 (also located on the driver's seat) (forward, neutral, reverse).
That is, it detects the direction point and outputs the detection signal to the interface 12. The load detection sensor 21 consists of a pressure sensor, and is connected to the lift cylinder 2.
2 detects the hydraulic pressure of the hydraulic oil in the fork 23.
The weight of the cargo 24 on the A/
D-hen 1! ! ! The signal is converted into a digital signal by the device 25 and output to the interface 12.

The microcomputer 31 is a central processing unit (hereinafter referred to as CP).
) 32, a program memory 33 consisting of a read-only memory (ROM) that stores control programs, and a working memory 34 consisting of a readable and rewritable memory (RAM) that temporarily stores arithmetic processing results, etc. The CPU 32 operates based on the program data stored in the program memory 33.

The CPU 32 receives detection signals from the sensors, switches, etc. through the interface 12. Then, the CPU 32 sequentially calculates the running speed Vx and acceleration ΔX of the forklift at that time based on the detection signal from the vehicle speed sensor 11, and also calculates the driving speed Vx and acceleration ΔX of the forklift at that time.
The engine rotation speed at that time is calculated based on the detection signal from 3, and the calculation result is stored in the working memory 34.

Similarly, the CPU 32 calculates the stroke amount of the rod 6a of the clutch control actuator 6 at that time based on the detection signal from the stroke detection sensor 14, that is, the connection state of the clutch 2, and Based on the detection signal, the depression angle ex of the Acvil pedal 17 at that time is calculated and stored in the working memory 3.
4 is stored.

Further, the CPtJ 31 determines the current direction point of the forward/reverse operation lever 20 based on the detection signal from the forward/reverse detection sensor 19, and also determines the current load Gx based on the detection signal from the load detection sensor 21, i.e. , calculates the severity of the cargo, and stores the calculation result in the working memory 34.

It should be noted that each calculation and judgment of these detection signals by the CPU 32 is performed exclusively based on data stored in the program memory 33 in advance.

Further, the CPU 32 controls the clutch control, shift switching, and forward/reverse switching actuators 6 via the interface 12 and each actuator drive circuit 35, 36, 37 based on predetermined program data.
-8 are drive-controlled. Furthermore, the CPU
32 controls the driving of the stepping motor 39 via the interface 12 and the motor drive circuit 38 based on predetermined program data. The motor 3 is drivingly connected to the throttle valve of the engine 1,
The opening degree of the throttle valve is controlled based on the rotary claw of the motor 39.

When the CPU 32 determines that the forward/reverse operating lever 20 has been switched to neutral during driving, the CPU 32 performs a running determination processing operation, that is, the forward/reverse operating lever 20 operated by the driver.
A processing operation is executed to determine whether the neutral operation is for switchback driving, inertial shift driving, or inertial driving.

Based on the determination result, the CPU 32 operates the clutch control, shift switching, and forward/reverse switching actuators 6 according to a predetermined program for switchback driving, coasting shift driving, or driving for coasting. -8 are drive-controlled.

In addition, when the automatic transmission 3 is switched in the opposite direction to the traveling direction during switchback traveling (to be described later), the CPU 32 controls the load GX according to the load GX at that time, that is, the weight of the cargo 24, as shown in FIG. Accelerator pedal 1 at that time
A negative acceleration An for the depression angle eX of No. 7 is determined in advance, and the forklift is controlled to achieve the negative acceleration An.

Note that the negative acceleration An with respect to the depression angle θX is calculated based on data stored in the program memory 33 in advance.

This negative acceleration control is performed by the CPIJ 32 controlling the connection state of the dry single plate clutch 2 (described later), that is, by controlling the amount of expansion and contraction of the O-rad 6a of the clutch control actuator 6.

Next, the operation of the electric block circuit configured as described above will be explained according to flowchart 1- shown in FIGS. 4 to 6.

Now, when the driver switches the forward/reverse operation lever 2° from forward to neutral while the forklift is moving forward at a predetermined traveling speed, the CPLI 32 changes the direction based on the detection signal from the forward/reverse detection sensor 19. In step 1), when determining that the point has not been switched to neutral, the clutch control actuator 6 is connected via the interface 12 and the actuator drive circuit 35.
drive control and disengage the dry single plate clutch 2 at maximum speed (
Step 2). At the same time, CPtJ32
2 is activated to determine whether the forward/reverse operation lever 20 has not been switched to a direction point other than neutral during a predetermined time (hereinafter referred to as set time t, 1 second in this embodiment). Do〈Step 3,
4).

Even if the set time t has elapsed, the forward/reverse operation lever 20
When is not operated and the direction point changes, the CPU 32 executes a coasting control processing operation to cause the forklift to coast (step 5). That is, the CPU 32 determines that coasting is occurring in response to the time-up, drives and controls the forward/reverse switching actuator 8 to change the gear of the automatic transmission 3 from forward to neutral, and then switches the gear of the automatic transmission 3 from forward to neutral. Connect. Therefore, the forklift will coast in this state.

On the other hand, when the operating lever 20 is switched to forward again within the set time, the CPU 32 determines that it is a coasting shift (step 6), and executes coasting shift control processing operation to make the forklift move forward again (step 7).
). CPtJ32 simply engages dry middle plate clutch 2 in response to the direction point not switching back to forward.

Therefore, the forklift will continue moving forward again.

Further, when the operating lever 20 is switched to reverse within the set time, the CPU 32 determines that a switchback has occurred (step 6), and executes a switchback control processing operation to cause the forklift to move backward (step 8).

In response to the direction point being switched from neutral to reverse, the CPU 32 drives and controls the stepping motor 39 to completely close the throttle valve (
Step 9). At the same time, the CPU 32 operates the clutch control actuator 6 to connect the dry single-plate clutch 2 and set the forklift speed [Vx] to the first reference speed Vl (in this embodiment, The engine brake is applied to decelerate the forklift until the speed at which the automatic transmission 3 can be switched from second speed to first speed is reached (step 10.11). At this time, the CPU 32 sets the first reference speed V1 at the current speed Vx calculated based on the detection signal from the vehicle speed sensor 11.
It is determined by successive comparison whether or not the speed has been reduced.

When the speed Vx becomes lower than the first reference speed V1, the CPU 3
Step 2 determines whether the automatic transmission 3 is in the second gear or first gear (step 12).

Then, when the automatic transmission 3 is in the first speed state, the CP
U32 determines whether the speed Vx, which will be described later, has been decelerated to a second reference speed v2 (in this embodiment, the speed at which the automatic transmission 3 can be switched from forward to reverse) stored in advance in the program memory 33. (Step 17)
.

On the other hand, when the automatic transmission 13 is in 2nd speed, the CPIJ 32 controls the clutch control actuator 6 to once disengage the dry single-plate clutch 2 (step 13), and then controls the shift switching actuator 7 via the actuator drive circuit 36. The automatic transmission 3 is controlled to switch gears from 2nd speed to 1st speed (step 14). And automatic transmission 3 is 1
When the forklift speed is switched to V
The engine brake is applied to decelerate the forklift until it reaches a predetermined second reference speed v2 (step 16.17).

When the speed VX becomes lower than the second reference speed V2, the CPU 3
2, after disengaging the dry single-plate clutch 2 in the same manner as described above (step 18), the automatic transmission 3
The gear is switched from forward to reverse (step 19). At the same time, the CPU 32 drives the stepping motor 39 to control the throttle valve, which has been completely closed, to an opening relative to the depression angle ex of the accelerator pedal 17. At the same time, control is performed to reverse the traveling direction (step 20).

When the automatic transmission 3 switches gears from forward to reverse (step 19), in order to further decelerate the forklift and make it run backwards immediately after stopping, the CPtJ32 detects the depression angle θX of the accelerator pedal 17 at that time using the pedal operation amount detection sensor. 16, and the current load GX is calculated based on the detection signal from the load detection sensor 21 (steps 21 and 22).

The CPtJ 32 selects data from the program memory 33 for calculating the negative acceleration An for the depression angle θX shown in FIG. 3 under the load GX at that time. and,
When the data for calculating the negative acceleration with respect to the depression angle ex is selected, the CPU 32 calculates the negative acceleration An with respect to the computed depression angle θX based on the selected data (step 23).

On the other hand, the CPIJ 32 performs differential processing on the detection signal from the vehicle speed detection sensor 11 to calculate the negative acceleration AX of the forklift at that time (steps 24 to 26). and,
This actual negative acceleration AX is the negative acceleration An obtained above.
The clutch control actuator 6 is actuated to control the connection state of the dry main root clutch 2 so that (steps 27 to 30). That is, when the actual negative acceleration AX is larger than the calculated negative acceleration An, the clutch 2 is disengaged (step 30); If it is smaller, the half-clutch connected state is controlled in the direction of connecting the clutch 2 so that the obtained negative acceleration becomes 0 (step 28).

Also, the actual negative acceleration AX is the calculated negative acceleration A
If it matches n, the CPtJ 32 controls the connected state of the clutch 2 to maintain the half-clutch state at that time (Step 29).

Therefore, in deceleration at this time, the negative acceleration An can be changed as appropriate depending on the depression angle ex of the accelerator pedal 17.

Then, the forklift decelerates to this negative acceleration according to 〇, reverses, moves backward, and completes switchback driving.

In this case, although the description has been made regarding traveling from forward to reverse, switchback travel from reverse to forward is also performed by the same processing operation.

In this way, in this embodiment, the negative acceleration An can be changed as appropriate according to the depression angle Cox of the accelerator pedal 17, so the reversal speed of switchback driving can be increased according to the driver's preference. Furthermore, the negative acceleration An with respect to the depression angle θX of the accelerator pedal 17 is made to correspond to the load Gx of the forklift, that is, the larger the load GX is, the smaller the negative acceleration An with respect to the depression angle ex becomes. Ideal smooth deceleration is always possible regardless of skill level and the presence or absence of cargo, and there is no risk of losing balance and overturning during deceleration.

Furthermore, in this embodiment, during switchback driving, engine braking is applied to decelerate the vehicle until the predetermined reference speeds Vl and V2 are reached before switching the automatic transmission 3 from forward to reverse. The automatic transmission 3 can be synchronized automatically for switching from 2nd gear to 1st gear and from forward to reverse, and the automatic transmission 3 can be shifted easily, without damaging the automatic transmission 3, and with the driver's skill level. The transmission can be smoothly changed for switchback driving regardless of the speed.

Furthermore, in this embodiment, when the forward/reverse operation lever 20 is switched to neutral while driving, the automatic transmission 3 is not immediately switched in response to the neutral, but is shifted during a predetermined time t. Since the driver is able to judge the driving (coasting driving, coasting shift driving, and switchback driving) that the driver is about to perform based on whether or not the next forward/reverse operation lever 20 is operated, the clutch switching drive means and It is possible to improve operability by eliminating unnecessary operations of the shift switching drive means of an automatic transmission, and
It is possible to reduce the burden on these driving means and improve durability.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and the set time t may be changed as appropriate within a range that does not interfere with driving, and the first and second reference speeds V1. V
2 may be applied to a forklift truck that is implemented by appropriately changing it, or it may be applied to a forklift truck that is implemented by setting the first and second reference speeds Vl and V2 to the same value.

Furthermore, in the deceleration control before switching from 66 forward to reverse in switchback control, the current traveling speed Vx
If the speed is large and it takes time to decelerate to the first M single speed (1), or if you want to decelerate faster, the CPU 32 may control the drive of the disc brake of the forklift to forcibly apply braking. In this case, when the speed is above a predetermined speed, the disc brake is applied to decelerate, and when the speed is below the set speed, the disc brake is released.

Furthermore, although the above embodiment was applied to a forklift,
It goes without saying that the present invention may be applied to other vehicles without deviating from the spirit of the present invention.

Effects of the Invention As detailed above, according to the first invention, a vehicle equipped with an automatic transmission can perform switchback driving similar to a vehicle with a manual transmission, and can smoothly perform switchback driving regardless of the skill of the driver. In addition to the effects of the first invention, the second invention enables more optimal switchback travel by controlling the deceleration rate in accordance with the load of the vehicle.

[Brief explanation of drawings]

Fig. 1 is a mechanical diagram showing the mechanism of the drive system of a forklift that embodies this invention, Fig. 2 is an electrical block circuit diagram of the forklift, and Fig. 3 shows the negative acceleration with respect to the depression angle of the accelerator pedal at each load. The figures showing the relationship, FIGS. 4 to 6, are flowcharts for explaining the operation of the forklift. In the figure, 1 is the engine, 2 is the dry single plate clutch, 3 is the automatic transmission, 6 is the clutch control actuator, 7 is the shift switching actuator, 8 is the forward/reverse switching actuator, 11 is the vehicle speed sensor, and 14 is the stroke detection sensor,
16 is a pedal operation amount detection sensor, 17 is an accelerator pedal, 19 is a forward/reverse motion detection sensor, 20 is a forward/reverse motion control lever,
21 is a load detection sensor, 24 is a cargo, 31 is a microcomputer, 32 is a central processing unit (CPU), 33 is a program memory, and 34 is a working memory. Patent applicant: Toyota Industries Corporation 1 Manufacturing Co., Ltd. θX-

Claims (1)

[Scope of Claims] 1. Automatic gear shifting that performs switchback driving by operating a forward/reverse control lever while driving to switch from a direction point that corresponds to the current direction of travel to a direction point that is in the opposite direction of travel. In a driving method for a vehicle equipped with a brake, a negative acceleration is set in advance for the depression angle of the accelerator pedal, and when the automatic transmission is switched in the opposite direction to the traveling direction based on the operation, the acceleration of the accelerator pedal at that time is set in advance. Compare the negative acceleration with respect to the depression angle and the actual negative acceleration of the vehicle at that time, and control the connection state of the clutch so that the actual negative acceleration becomes the negative acceleration with respect to the depression angle of the accelerator pedal. A clutch control method during switchback driving of a vehicle equipped with an automatic transmission. 2. A vehicle equipped with an automatic transmission that performs switchback driving by operating a forward/reverse control lever while driving to switch from a direction point that corresponds to the current direction of travel to a direction point that is in the opposite direction of travel. In the driving method, a plurality of negative accelerations are set in advance for different accelerator pedal operation amounts depending on the vehicle load, and when the automatic transmission is switched in the opposite direction to the traveling direction based on the operation, the current Compare the negative acceleration with respect to the depression angle of the accelerator pedal in the loaded state and the actual negative acceleration of the vehicle at that time, so that the actual negative acceleration becomes the negative acceleration with respect to the depression angle of the accelerator pedal in the loaded state, A clutch control method during switchback driving of a vehicle equipped with an automatic transmission that controls the connection state of a clutch.