JP2001114499A - Switch back controller for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a switch back capable of being smoothly braked when a switch back is operated during the traveling of an industrial vehicle. SOLUTION: A transmission 3 operationally connected to a torque converter 2 of an engine-type forklift truck comprises a forward clutch 8 and a backward clutch 9. A controller 41 controls a clutch valve 10decelerating zone to the stop of a vehicle when the switch back operationfor switching a shift lever 31 from the forward position to a backwardposition, or from the backward position to the forward position isdetected during the traveling of a forklift truck. Further the lockingof driving wheels 5 is detected on the basis of the rotating accelerationof the driving wheels 5 obtained from a detected value of a speed sensor17 during the deceleration, and a kind of ABS(antiskid brake system)control is executed for weakening the clutch engagement pressure ofthe shift side clutch when the locking of the driving wheels 5 isdetected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switchback control device for an industrial vehicle, such as a forklift, for performing suitable control at the time of switchback.

[0002]

2. Description of the Related Art Conventionally, forklifts include a transmission having a torque converter. In this type of forklift, a switchback operation of switching a shift lever (forward-backward switching lever) from a forward position to a reverse position or from a reverse position to a forward position during traveling is possible. Therefore, when the shift lever is switched back, the clutch is switched to the connection of the clutch on the opposite side to the traveling direction, so that the forklift rapidly decelerates with the switchback that applies braking in the traveling direction, and reverses the traveling direction after deceleration stop. Start in the direction opposite to the original direction of travel.

[0003]

During switchback deceleration, the engagement of the shift-side clutch, which attempts to transmit a reverse rotation driving force to the driving wheels, appears as a braking force on the driving wheels, and the deceleration due to this braking is reduced. There was a problem of deceleration shock. Also, during switchback deceleration, the drive wheels may be locked due to braking of the drive wheels. Locking of the drive wheels causes problems such as making tire marks (tire marks) on the floor of a factory or the like. Therefore, it has been desired that when a switchback operation is performed during traveling, the forklift switches back with smooth braking, thereby making it difficult to lock the drive wheels.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a first object of the present invention is to provide an industrial vehicle capable of realizing switchback for smoothly braking when a switchback operation is performed during traveling. A switchback control device is provided.

A second object is to prevent drive wheels from being locked during switchback deceleration. The third object is to prevent the driving wheels from being locked during switchback deceleration,
An object of the present invention is to prevent a drive wheel from slipping in a starting process after switchback is completed.

[0006]

According to the first aspect of the present invention, there is provided a hydraulic forward clutch and a reverse clutch for transmitting an output of an engine to an output shaft via a torque converter. , A control valve for adjusting the connection state by increasing or decreasing the hydraulic pressure in the pressure receiving chamber of each clutch, shift operation means for switching the transmission to a forward, neutral, or reverse state, and running the vehicle. Operation detection means for detecting a switchback operation for switching the shift operation means from forward to reverse, or from reverse to forward,
An engine control recognizing means for recognizing that a control end time for ending the braking relaxation control executed for mitigating the braking at the time of switchback has been reached; and The section until the control end time is recognized by the control recognition means is provided with engine speed control means for controlling the engine speed to be equal to or less than a preset upper limit value as the braking mitigation control.

According to this configuration, when the switch operation of the shift operation means is performed during running of the vehicle, the clutch on the traveling side is disengaged and the clutch on the opposite side is connected. As a result, the vehicle switches back, reverses after deceleration and stops, and starts in the direction opposite to the original traveling direction. The switchback operation at this time is detected by the operation detecting means. In the section from the control start time after the detection of the switchback operation to the recognition of the control end time by the engine control recognition means, the engine speed is controlled by the engine speed control means to be equal to or less than the preset upper limit value. You. Accordingly, since the braking force of the drive wheels is weakened by limiting the engine speed to a small value, the vehicle is smoothly braked at the time of switchback. Further, the deceleration shock of the vehicle during the switchback is suppressed to a small value, and the driving wheels are hardly locked.

According to a second aspect of the present invention, in the first aspect of the present invention, the engine control recognizing means determines that the vehicle has reached the stop vehicle speed after the switchback operation detected by the operation detecting means. This is a stop recognition unit that estimates or detects and recognizes the control end time.

According to this configuration, the engine speed is controlled to be equal to or less than the preset upper limit in a section after the switchback operation until the vehicle reaches the stop vehicle speed. Therefore, the vehicle is braked smoothly until the end of switchback.

[0010] To achieve the first object, a third aspect is provided.
In the invention described in the above, a transmission equipped with a hydraulic forward clutch and a reverse clutch for transmitting the output of the engine to the output shaft via a torque converter, and the connection state by increasing or decreasing the hydraulic pressure in the pressure receiving chamber of each clutch. A control valve for adjusting, a shift operating means for operating the transmission to switch between forward, neutral, and reverse, and a switchback operation for switching the shift operating means from forward to reverse or from reverse to forward while the vehicle is traveling. Operation detecting means for detecting, clutch recognizing means for recognizing that a control end time for ending the braking mitigation control performed to alleviate the braking at the time of switchback, and after the switchback operation is detected, The section from the control start timing until the control end timing is recognized by the clutch control recognition means to be the control end timing is the same as the braking relaxation control. A shift clutch and a clutch control means for controlling said control valve so as to half-clutch.

According to this configuration, when the shift operation means is switched back while the vehicle is running, the clutch on the traveling side is disengaged and the clutch on the opposite side is connected. As a result, the vehicle switches back, reverses after deceleration and stops, and starts in the direction opposite to the original traveling direction. The switchback operation at this time is detected by the operation detecting means. In a section from the control start timing after the detection of the switchback operation to the recognition of the control end timing by the clutch control recognizing means, the control valve is controlled by the clutch control means, and the shift side clutch is set to a half clutch. Accordingly, the braking force of the drive wheels is weakened by the half clutch, so that the vehicle is smoothly braked at the time of switchback. Also,
The deceleration shock of the vehicle during switchback is suppressed to a small value, and the driving wheels are also hard to lock.

According to a fourth aspect of the present invention, in the third aspect of the present invention, there is provided a load detecting means for detecting a load amount of a load loaded on the vehicle, and the clutch control means is configured to switch the vehicle at the time of switchback. In consideration of the load detected by the load detecting means, the control valve of the shift-side clutch is controlled such that the larger the load, the larger the clutch engagement pressure becomes, in consideration of the load detected by the load detecting means so that the feeling of deceleration is hardly affected by the load. Is the gist.

According to this structure, in addition to the operation of the third aspect of the invention, the clutch control means sets the shift-side clutch to a larger value as the load becomes heavier in consideration of the load detected by the load detector. Control to pressure. Therefore, without being affected by the presence or absence of loads on industrial vehicles,
During switchback deceleration, almost the same deceleration feeling is always obtained.

According to a fifth aspect of the present invention, in the third or fourth aspect of the invention, there is provided setting operation means for setting the deceleration intensity of the vehicle at the time of switchback, and the clutch control means comprises: The gist of the present invention is to control the control valve so that the clutch engagement pressure of the shift side clutch is set to a value corresponding to the set deceleration intensity set by the setting operation means.

According to this configuration, in addition to the operation of the third or fourth aspect, in the deceleration section during switchback, the clutch control means sets the clutch engagement pressure of the shift-side clutch to the deceleration set by the setting operation means. Control to a value according to the feeling. Therefore, during switchback, a sense of deceleration according to the driver's preference can be obtained.

According to the sixth aspect of the present invention, there is provided the third to fifth aspects.
In the invention according to any one of the first to third aspects, the apparatus further includes the engine control recognition unit and the engine speed control unit according to the first aspect.

According to this configuration, in addition to the operation of the invention according to any one of claims 3 to 5, in the deceleration section in which the vehicle speed is equal to or higher than the set vehicle speed during switchback, the engine speed is controlled by the engine speed control means. It is controlled to be equal to or less than a preset upper limit value. Therefore, the vehicle is more smoothly braked during the switchback by the deceleration suppressing action of both the half clutch of the shift side clutch and the suppression of the engine speed.

[0018] According to the invention described in claim 7, in claims 3 to 6
In the invention described in any one of the above, the control end time recognized by the clutch control recognition means is set in a section where the vehicle is at a stop vehicle speed, and the clutch control means is a clutch control recognition means. When it is recognized that the control end time has come, the gist of the present invention is to control the control valve so that the shift-side clutch is completely engaged.

According to this configuration, when the clutch control recognizing means recognizes that the control end time has come, the control valve is controlled by the clutch control means, and the shift-side clutch is completely engaged at once from the half-clutch state. Since the control end time is in the section where the vehicle is at the stop vehicle speed, the rotation difference between the input side and the output side of the shift side clutch is relatively small, and even if it is completely engaged at once, no shock is generated. Further, when the clutch is completely engaged from the half-clutch state, the holding time of the half-clutch state is shorter than in a configuration in which the clutch engagement pressure is restored with a speed gradient, thereby contributing to prevention of early wear of the clutch.

According to the invention described in claim 8, the claims 3 to 7 are provided.
In the invention according to any one of the above, the clutch control recognizing means recognizes the control end timing by estimating or detecting that the vehicle has reached the stop vehicle speed after the switchback operation detected by the operation detecting means. Stop recognition means.

According to this configuration, the shift-side clutch is maintained at the half-clutch until the vehicle reaches the stop vehicle speed after the switchback operation. Therefore, the vehicle is smoothly braked until the end of the switchback.

According to a ninth aspect of the present invention, there is provided a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to an output shaft via a torque converter. A transmission, a control valve for adjusting a connection state by increasing / decreasing a hydraulic pressure in a pressure receiving chamber of each clutch, shift operation means for switching the transmission to a forward / neutral / reverse state, and An operation detecting means for detecting a switchback operation for switching the shift operating means from forward to reverse or from reverse to forward, and a control end time for ending the braking mitigation control executed to ease the braking at the time of switchback. Lock prevention control recognizing means for recognizing that a lock of the drive wheel has been detected, and a control start timing after the switchback operation is detected. The section until the lock end control is recognized by the lock prevention control recognizing means until the lock end of the drive wheel is detected by the lock detecting means as the braking mitigation control. Anti-lock control means for controlling the control valve so as to weaken the combined pressure.

According to this configuration, when the switch operation of the shift operation means is performed during traveling of the vehicle, the clutch on the traveling side is disengaged and the clutch on the opposite side is connected. As a result, the vehicle switches back, reverses after deceleration and stops, and starts in the direction opposite to the original traveling direction. The switchback operation at this time is detected by the operation detecting means. In a section from the control start time after the detection of the switchback operation to the recognition of the control end time by the lock prevention control recognition means, when the lock of the drive wheel is detected by the lock detection means, the lock prevention control means As a result, the clutch engagement pressure of the shift side clutch is reduced. As a result, the lock of the drive wheels hardly occurs during the switchback, and the vehicle is braked smoothly.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, there is provided the engine control recognizing means and the engine speed control means according to the first or second aspect.

According to this structure, in addition to the effect of the ninth aspect of the present invention, the section from the control start timing after the detection of the switchback operation to the recognition of the control end timing by the engine control recognizing means includes the engine rotation. The number can be kept small below a preset upper limit. Therefore, due to the effect of the upper limit of the engine speed, the vehicle is more smoothly braked at the time of switchback, and the deceleration shock is suppressed to be small.

According to an eleventh aspect of the present invention, in the invention of the ninth or tenth aspect, there is provided the clutch control recognizing means and the clutch control means according to any one of the third to eighth aspects. I have.

According to this configuration, in addition to the operation of the ninth or tenth aspect, the section from the control start timing after the detection of the switchback operation to the recognition of the control end timing by the clutch control recognizing means is: The shift side clutch is changed to a half clutch by the clutch control means. Therefore,
At the time of switchback, the vehicle is braked more smoothly, and the deceleration shock is also reduced.

In the twelfth aspect of the present invention, the ninth to nineteenth aspects
In the invention described in any one of the eleventh to eleventh aspects, the lock prevention control means may adjust the clutch engagement pressure at the time of return after weakening during detection of lock of the drive wheel to balance the drive force of the drive wheel with the road surface resistance. The gist of the present invention is to perform control to gradually lower the temperature so as to converge to a point.

According to this configuration, in addition to the function of the invention of any one of claims 9 to 11, the lock prevention control means may include:
The clutch engagement pressure when the lock of the drive wheel is no longer detected and the clutch engagement pressure of the shift-side clutch is restored is gradually reduced so that the drive force of the drive wheel converges to the equilibrium point with the road surface resistance. As a result, the driving force of the driving wheels finally substantially converges to an equilibrium point where the driving force is balanced with the road surface resistance. Therefore, it is possible to avoid a situation where the deceleration is unnecessarily weakened excessively due to the drive wheel lock prevention control.

According to the thirteenth aspect, in the twelfth aspect,
In the invention described in the above, the lock detecting means detects the rotation deceleration of the driving wheel, and when it is determined that the rotation deceleration exceeds a preset lock threshold value, the drive wheel is locked. The lock prevention control means gradually reduces the clutch engagement pressure at the time of return at a reduction rate according to an integral value of a portion where the rotation deceleration of the drive wheel exceeds the correction threshold value. The point is to control.

According to this configuration, in addition to the function of the twelfth aspect, the lock detecting means detects that the drive wheel is locked when the rotation deceleration of the drive wheel exceeds the lock threshold value. The lock prevention control means reduces the clutch engagement pressure at a reduction rate corresponding to the integral value of a portion (region) where the rotation deceleration of the drive wheel exceeds the correction threshold value. Therefore, while the lock of the drive wheel is intense, the correction amount of the clutch engagement pressure at the time of return is large, and as the lock of the drive wheel becomes weak, the correction amount of the clutch engagement pressure gradually decreases. Therefore, the driving force of the driving wheels quickly converges to the equilibrium point where the driving force balances with the road surface resistance, and the frequency of occurrence of the locking of the driving wheels decreases.

[0032] In order to achieve the third object, a first aspect is provided.
According to a fourth aspect of the present invention, in the first aspect of the present invention, the control start for starting the slip prevention control for preventing the drive wheels from slipping in the starting process after the switchback is performed. The slip prevention control recognizing means for recognizing that the time has come, the slip detecting means for detecting the slip of the drive wheel, and the slip prevention control recognizing means recognize that the control start time has come. Slip prevention control means for controlling the control valve so as to reduce the clutch engagement pressure of the shift-side clutch when slippage of the drive wheels is detected by the detection means.

According to this configuration, in addition to the function of any one of the ninth to thirteenth aspects, the slip of the drive wheel is detected after the slip prevention control recognition means recognizes that the control start time has come. Then, the control valve is controlled by the slip prevention control means, and the clutch engagement pressure of the shift side clutch is reduced. As a result, slippage of the drive wheels hardly occurs. Therefore, the lock of the drive wheel hardly occurs during the switchback, and the slip of the drive wheel hardly occurs at the time of starting after the switchback is completed.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is embodied in a forklift as an industrial vehicle will be described below with reference to the drawings.

As shown in FIG. 1, the output shaft 1 of the engine 1
a is connected to a transmission 3 having a torque converter 2;
The transmission 3 is connected via a differential 4 to an axle 6 having drive wheels 5.
It is connected to. The throttle actuator 7 is provided in the engine 1, and the throttle opening is adjusted by the operation of the throttle actuator 7 to adjust the rotation speed of the engine 1, that is, the rotation speed of the output shaft 1 a of the engine 1.

The transmission 3 has an input shaft (main shaft) 3a.
And an output shaft (counter shaft) 3b.
a is provided with a forward clutch 8 and a reverse clutch 9. A gear train (not shown) is provided between the forward clutch 8 and the reverse clutch 9 and the output shaft 3b, respectively, and the rotation of the input shaft 3a is transmitted to the output shaft 3b via each clutch 8, 9 and each gear train. . A hydraulic clutch, a wet multi-plate clutch in this embodiment, is used for both clutches 8 and 9, and the connection force can be adjusted by the oil pressure in the pressure receiving chambers 8a and 9a, and the oil in the pressure receiving chambers 8a and 9a can be adjusted. The connection force is configured to increase as the pressure is increased. The hydraulic pressure in the pressure receiving chambers 8a and 9a of the forward clutch 8 and the reverse clutch 9 is controlled by hydraulic pressure supplied through a forward clutch valve 10 and a reverse clutch valve 11 as control valves. Forward clutch valve 10 and reverse clutch valve 1
Reference numeral 1 denotes a proportional solenoid valve having an opening proportional to the amount of current supplied to the solenoid.

A clutch type parking brake 12 is provided on the output shaft 3b of the transmission 3. The parking brake 12 includes a disk 12a that rotates integrally with the output shaft 3b,
and a brake pad 12b provided so as not to rotate with respect to b and to be movable in the thrust direction. The parking brake 12 is configured to be braked by controlling the hydraulic pressure of the pressure receiving chamber 12c via the brake valve 13. An electromagnetic valve is used as the brake valve 13.

Although FIG. 1 shows the torque converter 2, the transmission 3, and the valves 10, 11, and 13 independently, these devices are incorporated in one housing to constitute an automatic transmission. I have. A hydraulic pump (not shown) is incorporated in the transmission 3, and the discharge oil of the hydraulic pump is supplied to each of the pressure receiving chambers 8 a and 9 through a flow path (not shown) and each of the valves 10, 11 and 13.
a, 12c. The hydraulic pump is driven by a rotational force transmitted to the transmission 3 when the engine 1 rotates.

A gear 14 is provided on the input shaft 3a of the transmission 3 so as to be integrally rotatable, and the rotation speed of the input shaft 3a is detected by a turbine speed sensor 15 comprising a magnetic pickup. The turbine speed sensor 15 outputs a pulse signal proportional to the speed of the input shaft 3a. Output shaft 3 of transmission 3
A gear 16 is provided in b so as to be integrally rotatable, and the rotation speed of the output shaft 3b is detected by a vehicle speed sensor 17 comprising a magnetic pickup as vehicle speed detection means. Vehicle speed sensor 17
Outputs a pulse signal proportional to the rotation speed of the output shaft 3b.

A lift cylinder 20 for raising and lowering the fork 19 and a tilt cylinder (not shown) for tilting the mast 21 are connected to the discharge side of a loading / unloading pump (hydraulic pump) 18 driven by the engine 1 via a pipe (not shown). Have been. The lift cylinder 20 has a fork 19
A load sensor 22 is provided as load detecting means for detecting the weight (load) of the load loaded on the vehicle. The load sensor 22 includes a pressure sensor that detects the oil pressure inside the lift cylinder 20 and outputs a detection signal corresponding to the load of the fork 19.

An accelerator pedal 23, an inching pedal 24, and a brake pedal 25 are provided on the floor of the cab. The inching pedal 24 is used to bring the clutch into a half-engaged state (half-clutch state) when the forklift travels at a very low speed while performing a cargo handling operation. When the brake pedal 25 is operated (depressed), the brake pedal 25 operates independently of the inching pedal 24. However, when the inching pedal 24 is operated (depressed), the inching pedal 24 and the brake pedal 25 are operated halfway. Is configured to be able to be linked.

An accelerator sensor 26 for detecting the operation amount of the accelerator pedal 23 outputs a detection signal proportional to the operation amount of the accelerator pedal 23. The inching sensor 27 that detects the operation amount of the inching pedal 24 outputs a detection signal proportional to the operation amount of the inching sensor 27.

The brake pedal 25 is mechanically connected to a hydraulic pedaling force generator (emulator) 28, and the pedaling force generator 28 is provided with a brake sensor 29 composed of a pressure sensor for detecting the internal oil pressure. The brake sensor 29 outputs a detection signal proportional to the brake depression force when the brake pedal 25 is depressed. Whether or not the brake pedal 25 has been operated is detected by the brake switch 30.

A shift lever (forward / reverse lever) 31 as a shift operation means is provided at the front of the cab.
Shift switch 32 for detecting the position of shift lever 31
Detects whether the shift lever 31 is in the forward position F, the reverse position R, or the neutral position (neutral position) N, and outputs a signal corresponding to each position. A lift lever 33 and a tilt lever 34 are provided at the front of the cab. The lift lever sensor 35 that detects the operation amount of the lift lever 33 outputs a detection signal proportional to the operation amount of the lift lever 33. The tilt lever sensor 36 that detects the amount of operation of the tilt lever 34 outputs a detection signal proportional to the amount of operation of the tilt lever 34. A mode changeover switch 37 as a setting operation means is provided at the front of the cab. The engine speed is detected by an engine speed sensor 38 built in the engine 1. The engine speed sensor 38 outputs a pulse signal proportional to the engine speed.

Next, an electrical configuration for controlling the drive of the throttle actuator 7, the forward clutch valve 10, the reverse clutch valve 11, and the brake valve 13 will be described.

The control device 41 includes a central processing unit (hereinafter referred to as C).
PU) 42, read-only memory (ROM) 43,
It has a readable and rewritable memory (RAM) 44, an input interface 45 and an output interface 46. The ROM 43 stores a predetermined control program and various data required for executing the control program. The RAM 44 temporarily stores the calculation results of the CPU 42 and the like. The CPU 42 operates based on a control program stored in the ROM 43. The operation detecting means is constituted by the control device 41 and the shift switch 32.
The engine speed control means includes a control device 41 and the throttle actuator 7. Clutch control means, lock prevention control means and slip prevention control means,
It is constituted by a control device 41 and clutch valves 10 and 11. Further, the engine control recognition means, the clutch control recognition means, the lock prevention control recognition means, the slip prevention control recognition means, the stop recognition means, the lock detection means and the slip detection means are constituted by the control device 41 and the vehicle speed sensor 17. Is done.

The CPU 42 controls the sensors 15, 17, 2
2, 26, 27, 29, 35, 36, 38 and the output signals of the switches 30, 32, 37
It operates according to various control programs stored in the OM 43, and operates the throttle actuator 7 and the valves 10, 1
1 and 13 are outputted.

The turbine speed sensor 15, vehicle speed sensor 17, brake switch 30, shift switch 32,
Mode switch 37 and engine speed sensor 38
Are connected to the CPU 42 via the input interface 45. The load sensor 22, the accelerator sensor 26, the inching sensor 27, the brake sensor 29, the lift lever sensor 35, and the tilt lever sensor 36 are connected to the CPU 42 via an A / D converter (analog / digital converter) and an input interface 45 (not shown). Have been.

The CPU 42 controls the throttle actuator 7, the forward clutch valve 10, the reverse clutch valve 11 via an output interface 46 and a drive circuit (not shown).
And the brake valve 13.

Various programs (FIGS. 8 to 8) are stored in the ROM 43.
12) and various maps (FIGS. 2 to 5) used in various programs. Each program is executed at predetermined time intervals (for example, 10 to 50 msec.) While the engine is operating (while the starter key is on).

FIG. 8 shows a program for executing switchback control. This program includes an SB engine speed control routine shown in FIG. 9 and an SB engine speed control routine shown in FIG.
A clutch pressure control routine is included. The maps M1 and M2 of FIGS. 2 and 3 are used in the routine of FIG. 9, and the map M3 of FIG. 4 is used in the routine of FIG.

FIGS. 11 and 12 show a start control program after switchback is completed. The start engine speed control routine (FIG. 11) and the start clutch pressure control routine (FIG. 1)
2). The map M5 of FIG. 5 is used in the routine of FIG.

In the present embodiment, a suitable deceleration feeling with less deceleration shock during switchback deceleration is obtained.
A clutch pressure control that adjusts the shift side (connection side) clutch to the engagement pressure of the half clutch is adopted. Since the deceleration of the vehicle is affected by the weight of the vehicle body, the clutch engagement pressure is set in consideration of the weight (load) of the load loaded on the forklift. The map M3 in FIG. 4 is used for setting the clutch engagement pressure in consideration of the load.

In the switchback deceleration process, a kind of ABS (anti-skid brake system) control for preventing the driving wheels 5 from being locked is employed. By reducing the engagement pressure of the shift-side clutch when the lock of the drive wheel 5 is detected during the switchback, the braking force generated by engagement of the clutch of the shift on the opposite side in the traveling direction is reduced. In the ABS control, when the rotational acceleration of the drive wheel 5 takes a value that cannot be obtained by deceleration during switchback, it is determined that the tire is locked. The rotational acceleration of the driving wheel 5 uses the acceleration obtained from the time difference of the vehicle speed detected by the vehicle speed sensor 17 and when the acceleration exceeds the lock determination threshold value on the negative side, that is, when the deceleration exceeds the threshold value. It is determined that the tire is locked.

During tire lock detection, the clutch engagement pressure is released to a predetermined pressure, and when tire lock is no longer detected, the clutch engagement pressure is restored. repeat. At this time, the return pressure of the clutch engagement pressure is set to a value that is gradually smaller than the previous value, so that the driving force of the driving wheels 5 is balanced with the road surface resistance and converges to an equilibrium point at which locking does not occur just before.
The above is performed in the SB clutch pressure control routine.

Furthermore, during switchback deceleration, an upper limit value is set for the engine speed, and control is performed to keep the engine speed lower than the upper limit value, so that the braking force generated by the engagement of the shift-side clutch is reduced. I have to. This is the SB engine speed control routine (FIG. 9)
Done in

On the other hand, in the starting process after the end of the switchback, the initial clutch pressure is applied and the half clutch is maintained for a certain period of time to realize a smooth start after the switching of the traveling direction. Also, in this starting process,
A kind of TRC (traction control) control for preventing the slip of the driving wheel 5 is employed. The basic concept of the TRC control is the same as that of the ABS control. The clutch engagement pressure is reduced to a predetermined pressure while tire slip is detected, and the clutch engagement pressure is restored when tire slip is no longer detected. Thereafter, every time the tire slip is detected, the release / entry of the clutch engagement pressure is repeated. If the rotational acceleration of the drive wheel 5 takes a value that is not possible when the forklift is started, it is determined that a tire slip has occurred. The rotational acceleration of the drive wheel 5 uses the acceleration obtained from the time difference of the vehicle speed detected by the vehicle speed sensor 17, and when the acceleration exceeds the slip determination threshold value to the positive side, it is determined that the tire is slip. At this time, the return pressure of the clutch engagement pressure is set to a value that is gradually smaller than the previous value, so that the driving force of the driving wheels 5 is balanced with the road surface resistance and converges to an equilibrium point at which slippage does not occur. The above is performed in the starting clutch pressure control routine. Further, during execution of the TRC control, control is performed to keep the engine speed low, and this is performed in the starting engine speed control routine.

When the brake pedal 25 is depressed, a braking system is employed in which the forward and backward clutches 8, 9 are simultaneously engaged to obtain a braking force. For this reason, a drum brake or the like is not provided as a service brake. The parking brake 12 may be used as another braking method. Of course, a drum brake may be provided on the drive wheel 5 as a regular brake, and a brake system using the drum brake may be employed. In addition,
If a brake operation is performed during switchback, the brake pressure control is given priority over the clutch pressure control.
In this case, in the brake control, the forward / reverse clutch 8,
The ABS control of the same system as that at the time of the switchback control is performed on the simultaneous engagement clutch pressure of No. 9.

Next, the program content of each routine shown in FIGS. 8 to 12 will be described. First, the SB engine speed control routine of FIG. 8 will be described. First, in step (hereinafter simply referred to as S) 10, it is determined whether a switchback operation has been performed. When the shift lever 31 is switched from the F position to the R position or from the R position to the F position during traveling (vehicle speed V> 0), it is determined that the switchback operation has been performed. When it is determined that the switchback operation has been performed, the process proceeds to S20, and when it is not determined that the switchback operation has been performed, the process proceeds to S50.

In S20, "1" is set to the flag Fsb. The flag Fsb = 1 means that the switchback is being performed. In the next S30, an estimated time Tsb required for stopping the vehicle is calculated. Using the preset assumed acceleration (deceleration) αst during switchback and the detected vehicle speed Vst at the time of switchback operation, the equation Tsb = Vst
Calculated from / αst.

At the next S40, the time Tsb is stored in the SB counter.
Is set to the count value SBcnt corresponding to. In S50,
It is determined whether or not switchback is being performed (Fsb = 1). If the flag Fsb = 1, the process proceeds to S60. If the flag Fsb = 1, the routine ends.

At S60, the count value SBcn of the SB counter is set.
It is determined whether or not t is positive (SBcnt> 0). That is, it is determined whether or not the estimated time Tsb required from the time of the switchback operation to the stop of the vehicle has not elapsed, and the vehicle is in the switchback deceleration process.

In S70, the vehicle speed V is the stop vehicle speed (V
≤ Vo). The stop vehicle speed (V ≦ Vo) is a sufficiently low vehicle speed that does not cause much shock even if the clutch is completely engaged. For example, Vo is a value in the range of 0 to 5 km / h.

At S60, after the expected time Tsb has passed, S
If Bcnt> 0 is not satisfied and it is confirmed in S70 that the vehicle speed has reached the stop vehicle speed (V ≦ Vo), the routine shifts from the routine to the start control routine. At this time, the flag Fsb is reset (Fsb = 0). On the other hand, until S70 is established after S60 is not established, S
The processing of 80 to S100 is executed.

At S80, the SB engine speed control (FIG. 9) is executed. In S90, SB clutch pressure control (FIG. 10) is executed. In S100, the count SBcnt is decremented.

Therefore, if a switchback operation for switching the shift lever 31 to the reverse direction is performed during traveling, after the expected time Tsb required for stopping has elapsed, the vehicle speed V further decreases until the vehicle speed V reaches the stop vehicle speed (V ≦ Vo). During this period, the SB engine speed control (FIG. 9) and the SB clutch pressure control (FIG. 10) are executed.

Next, the SB engine speed control routine shown in FIG. 9 will be described. First, in S110, the engine speed upper limit value NEsb according to the load is determined with reference to the map M1 (FIG. 2). The load uses the detection value of the load sensor 22.

In S120, a target engine speed NEtrg corresponding to the accelerator opening is obtained with reference to a map M2 (FIG. 3). In S130, the target engine speed NEtrg
Is larger than the engine speed upper limit NEsb (NEtrg>
NEsb). This condition NEtrg> NEsb
When the condition is satisfied, the process proceeds to S140, and when this condition is not satisfied, the process proceeds to S150.

At S140, the target engine speed NEtr
Set the engine speed upper limit value NEsb to g. S15
At 0, a throttle opening THtrg for setting the target engine speed NEtrg to the throttle actuator 7 is commanded.

Therefore, by executing this routine, after the switchback operation is detected, it is estimated that the vehicle has stopped (vehicle speed "0") after the expected time Tsb has elapsed, and then the vehicle speed V is equal to the stopped vehicle speed (V In the section until it is confirmed that ≤ Vo), the engine speed is limited to the upper limit value NEsb or less.

Next, the SB clutch pressure control routine shown in FIG. 10 will be described. First, in S210, this routine execution 1
It is determined whether it is the first time. For example, when the flag Fsb is switched from “0” to “1”, it is determined to be the first time.

In S220, the clutch engagement pressure Phr according to the load is determined with reference to a map M3 (FIG. 4). The deceleration of the vehicle during switchback is determined by the clutch engagement pressure Phr.

The following steps S230 to S260 are preparations for determining a correction amount for correcting the clutch engagement pressure Phr during the ABS control. As shown in FIG. 6, in the ABS control, when the acceleration acc exceeds the tire lock threshold value Alock on the negative side, the clutch engagement pressure Pcl is reduced to a value Po.
When the tire lock is released and the clutch engagement pressure is restored again, the clutch engagement pressure Pcl is corrected to a value smaller than the previous clutch engagement pressure. This correction amount is obtained by setting the set value A1mode slightly larger than the threshold value Alock to the acceleration ac.
Integral value of area where c is less than (area of hatched area) intg
A, and the integral value in is calculated from the clutch engagement pressure Phr.
By subtracting the ratio (reduction rate) corresponding to tgA,
Each time the clutch engagement pressure P is gradually reduced during ABS execution
cl is determined.

The processing contents are as follows. S230
Then, acceleration acc = V1−V2 is calculated. Where V
1 is the current vehicle speed, and V2 is the previous vehicle speed. Since the vehicle speed sensor 17 indirectly detects the rotational speed of the drive wheel 5, the acceleration acc is a value proportional to the rotational acceleration of the drive wheel 5. The acceleration acc during switchback is negative (acc <
0).

At S240, Δacc = A1mode-ac
Calculate c. Δacc indicates that the acceleration acc is the set value A1
Takes a positive value below mode. Here, the set value A1
mode corresponds to the correction threshold.

In S250, Δacc is subjected to numerical value limiting processing to obtain ΔA (0 ≦ ΔA ≦ α). That is, when Δacc takes a negative value, it is set to “0”, and when Δacc takes a value exceeding the value α, it is set to “α”. Therefore, the acceleration acc is equal to the set value A.
Only Δacc (however, the upper limit value α) which takes a positive value below 1 mode remains as ΔA. Here, α is an upper limit value using the integrated value (accumulated value) of ΔA to avoid a sudden increase in the correction amount determined in the subsequent processing.

In S260, the integral value intgA = ΔA + intg
Calculate A. That is, the previous integral value intgA is replaced by the current ΔA
Is added. The integral value intgA, which is the cumulative value of ΔA, corresponds to the area of the region where the acceleration acc is lower than the set value A1mode (see FIG. 6).

In S270, it is determined whether or not the acceleration acc is smaller than a lock determination threshold value Alock (acc <Alock). That is, it is determined whether the tire lock has been detected. If tire lock is not detected, S28
The process proceeds to 0, and if a tire lock is detected, the process proceeds to S300.

In S300, "1" is set to the flag Fabs. That is, tire slip is detected and ABS
When the mode is set, the flag Fabs = 1. On the other hand, S28
At 0, it is determined whether or not the flag Fabs = 1. F
If abs = 1, Phr is adopted as the clutch engagement pressure (clutch pressure) Pcl in S290. Then, in S340, the shift-side clutch valve is
A current value IPcl corresponding to the clutch pressure Phr is commanded. For this reason, during switchback, the forklift decelerates at the assumed deceleration αst determined by the clutch pressure Phr, and the clutch pressure Phr considering the load is adopted, so that the assumed deceleration αst is always obtained regardless of the load value. Can be

On the other hand, when tire lock is detected in S270, the flag Fabs is set to 1 (S300).
Thereafter, Po is adopted as the clutch pressure Pcl in S310. Then, in S340, a current value IPo corresponding to the clutch pressure Po is instructed to the shift side clutch valve. Therefore, when the tire lock is detected, the engagement pressure of the shift side clutch is released to the clutch pressure Po (see FIG. 6).

After entering the ABS mode, when the tire lock is not detected in S270, the clutch pressure is restored again. However, in S280, the ABS mode is set (F
If it is determined that abs = 1), the return clutch pressure Pcl is calculated in S320 and S330.

At S320, the integral value intgA is normalized. That is, the integral value intgA is divided by a certain reference value, and 0 ≦ S
A normalized value Ser of the integral value intgA that satisfies er ≦ 1 is calculated. In S330, the clutch pressure Pcl = (1-Ser)
-Calculate Phr. In other words, the integral value for the clutch pressure Phr
A value smaller by the ratio corresponding to intgA is calculated as the clutch pressure Pcl.

In step S340, a current value IPcl corresponding to the clutch pressure (1-Ser) · Phr is instructed to the shift-side clutch valve. For this reason, the clutch pressure at the time of the return in the ABS mode is the clutch pressure Pcl corrected to be smaller than the clutch pressure Phr by a ratio corresponding to the integral value intgA (see FIG. 6). For this reason, the clutch pressure Pcl at the time of recovery gradually decreases every time the tire lock is detected, and the reduction rate of the current value with respect to the previous value gradually decreases. As a result, the driving force of the driving wheels 5 balances with the road surface resistance and converges to an equilibrium point at which tire lock does not occur. In the ABS mode (Fabs =
1) is, for example, a difference value ΔAlock in the ABS mode.
(= Alock-acc) integrated value intΔAlock
Is reset when the condition of intgAlock <0 is satisfied (Fab
s = 0). When the clutch engagement pressure Pcl converges to the value at the equilibrium point and the acceleration acc is settled to a value near the threshold Alock, intgAlock <0 is finally established, and Fabs = 0. When Fabs = 0, the integral values intgA and intΔAlock are both reset to “0”.

Next, a start control routine after the switchback is completed will be described. First, a start engine speed control routine shown in FIG. 11 will be described. First, in S400, the target engine speed NEtrg corresponding to the accelerator opening is set.
Is obtained with reference to the map M2 (FIG. 3).

At S410, the acceleration acc = V1-V2
Is calculated. The acceleration acc is a value proportional to the rotational acceleration of the driving wheel 5. Acceleration a at start after switchback
cc takes a positive (acc> 0) value.

In S420, it is determined whether or not the acceleration "ac" exceeds a threshold value "Slip" for slip determination (acc> Aslip). That is, it is determined whether tire slip has been detected. When tire slip is detected, S430 is performed.
To S440 if tire slip is not detected
Proceed to.

In S430, "1" is set to the flag Ftrc. That is, tire slip is detected and TRC
It is assumed that the mode has been set and the flag Ftrc = 1. S44
If it is 0, it is determined whether or not the flag Ftrc = 1. F
If trc = 1, the process proceeds to S450, and if Ftrc = 1, the process proceeds to S500.

At S450, Δacc = acc−Aslip
Is calculated. Δacc means that the acceleration acc is equal to the threshold value Asl
It takes a positive value when it exceeds ip and a negative value when it falls below ip.
In S460, the integral value intgB = Δ, which is the accumulation of Δacc
Calculate acc + intgB. Acceleration a during TRC mode
cc takes a value that swings up and down with respect to the threshold value Aslip by TRC control (clutch pressure control) described later, and is integrated before the driving force of the driving wheels 5 converges to a clutch pressure balanced with the road surface resistance. The value intB takes a positive value (intg
B> 0).

In S470, it is determined whether or not intgB> 0. That is, it is determined whether or not the driving force of the driving wheels 5 has converged to a clutch pressure that balances with the road surface resistance.
If intgB> 0, the process proceeds to S480. If intgB> 0, the process proceeds to S490.

In S480, the target engine speed NEtr
Set the idle speed NEo in g. That is, TRC
During the mode, the idle speed NEo is employed. S49
If 0, the flag Ftrc is reset (Ftrc = 0).
That is, the TRC mode ends.

In S500, the target engine speed NEtr
The throttle actuator THtrg to be g is commanded to the throttle actuator 7. Therefore, while the intgB> 0 holds, the TRC mode is regarded and the engine speed is suppressed to the idle speed. For this reason, when trying to lower the engine speed only when tire slip is detected,
IntgB where timing may not be well taken due to delay in response to engine speed, but tire slip may occur
Since the engine speed is kept low while> 0 holds, the problem of timing mismatch due to a delay in the response of the engine speed is solved.

Next, the starting clutch pressure control routine shown in FIG. 12 will be described. In S510, it is determined whether this is the first time after execution of this routine. If it is the first time, the process proceeds to S520, and if it is the second or later time, the process proceeds to S530.

In S520, an initial clutch engagement pressure Pclini corresponding to the load is obtained with reference to a map M4 (FIG. 5). In S530, the clutch pressure Pclini = Pclini + Δ
Calculate P. That is, the initial clutch pressure Pclini is increased at a constant gradient.

Steps S540 and S550 are preparation processing for determining a correction amount for correcting the clutch engagement pressure Pclini during TRC control. In the TRC control, the clutch pressure Pclini is reduced to the value Po when the acceleration acc exceeds the tire slip threshold value Aslip, and the clutch pressure Pcl at the time of return after the tire slip has been eliminated is smaller than the previous clutch pressure. Correct the value. The basic concept of determining the correction amount is the same as that of the ABS control, and the set value A2mode slightly smaller than the threshold value Aslip is set to the acceleration a.
Ratio (reduction rate) according to integral value ΔA in the region where cc exceeds
Is subtracted from the clutch engagement pressure Pclini.

The processing contents are as follows. S540
Then, Δacc = acc−A2mode is calculated. The acceleration "acc" uses the value (S410) previously calculated in the starting engine speed control routine. Δacc is the acceleration ac
Set value A2mode where c is a threshold value for slip correction
Takes a positive value when exceeds.

In step S550, the integral value intgA = ΔA is calculated using ΔA (0 ≦ ΔA ≦ α) obtained by numerically limiting Δacc.
Calculate + intgA. The integral value intgA corresponds to the area of the region where the acceleration acc exceeds the set value A2mode (see FIG. 7).

In S560, it is determined whether or not the time Tst counted from the start of the start control has exceeded a predetermined time Ts. If the predetermined time Ts has not elapsed, the process proceeds to S570, and if the predetermined time Ts has elapsed, the process proceeds to S630.

In S570, the acceleration acc is set to the threshold value A.
It is determined whether or not slip is exceeded (acc> Aslip). That is, it is determined whether tire slip has been detected. When the tire slip is not detected, the process proceeds to S580, and when the tire slip is detected, the process proceeds to S600.

In S580, it is determined whether or not the flag Ftrc = 1. That is, it is determined whether the mode is the TRC mode. If Ftrc is not 1, Pclini is adopted as the clutch pressure Pcl in S590. As the initial clutch pressure Pclini at this time before the lapse of the predetermined time Ts, a value changed in S530 so as to increase at a constant gradient with the lapse of time is adopted. On the other hand, when it is determined in S560 that the predetermined time Ts has elapsed, in S630, the full engagement pressure Pc is adopted as the clutch pressure Pcl.

At S640, the current value IP corresponding to the clutch pressure Pcl is applied to the shift side clutch valve.
Command cl. For this reason, the initial clutch pressure clini in consideration of the load is adopted, and the clutch pressure increases at a constant gradient, and after a predetermined time Ts has elapsed, the shift-side clutch is completely engaged. Therefore, after the switchback is completed, a constant starting acceleration is always obtained without being affected by the load.

On the other hand, if tire slip is detected in S570, Po is adopted as clutch pressure Pcl in S600. In S640, a current value IPcl corresponding to the clutch pressure Po is instructed to the shift side clutch valve. Therefore, when tire slip is detected, the clutch pressure is released to Po (see FIG. 7).

After entering the TRC mode, if the tire slip is not detected in S570, the clutch pressure is returned again. However, if it is determined in S580 that the TRC mode is set (Ftrc = 1), the clutch in recovery is returned in S610 and S620. Calculate the pressure Pcl.

At S610, the normalized value S of the integral value intgA is calculated.
er (0 ≦ Ser ≦ 1) is calculated. In S620, the clutch pressure Pcl is calculated by the equation Pcl = (1-Ser) · Pclini
Calculate from That is, the clutch pressure Pcl corrected to a value smaller than the clutch pressure Pclini by a ratio corresponding to the integral value intgA is calculated.

At S640, the clutch pressure Pcl = (1-Ser) · P is applied to the shift side clutch valve.
Command current value IPcl corresponding to clini. For this reason,
While the tire slip is detected in the TRC mode, the clutch pressure Pcl at the time of return gradually decreases, and the driving force of the drive wheels 5 balances with the road surface resistance and converges to a clutch pressure at an equilibrium point at which tire slip does not barely occur. .

Therefore, when the switchback operation is performed by executing the above routines, the following control is performed. As shown in FIG. 7, for example, it is assumed that a switchback operation of switching the shift lever 31 from the F position to the R position at a time To while the forklift is traveling forward. Then, the forward clutch 8 on the F position side is disengaged and at the same time R
The reverse clutch 9 on the position side is connected. At this time, the clutch engagement pressure Phr of the half clutch considering the load is adopted. In addition, the engine speed can be kept low below the upper limit NEsb. In the SB clutch pressure control for holding the shift clutch in the half-clutch state and the SB engine speed control for limiting the engine speed to the upper limit or less, the vehicle speed is at the stop vehicle speed after the elapse of the estimated time Tsb until the vehicle stops. (V ≦ V
The section until confirmation of o) is continued. as a result,
During switchback, the forklift decelerates smoothly. At this time, the determination as to whether or not the vehicle speed V has reached the stop vehicle speed (V ≦ Vo) is made after the elapse of the estimated time Tsb (that is, after the vehicle stops), so that the drive wheels 5 during switchback are locked. In addition, an erroneous determination that the vehicle speed has stopped can be avoided.

During the switchback, if the drive wheels 5 are locked even if the vehicle is suppressed to the half clutch deceleration, the ABS control is executed. That is, the clutch pressure Pcl
Is released to the predetermined pressure Po during lock detection, and when the clutch pressure is restored, the clutch pressure Pcl is gradually decreased at a reduction rate corresponding to the integral value in the region where the acceleration acc exceeds the set value A1mode on the negative side. Therefore, the driving force of the driving wheel 5 converges to a substantially equilibrium point where the driving force is balanced with the road surface resistance by the ABS control (see FIGS. 6 and 7).

When the expected time Tsb has elapsed from the time of the switchback operation and the vehicle speed V is confirmed to be at the stop vehicle speed (V ≦ Vo), the switchback control ends and the start control starts. In the start control, the engine speed is determined to a value corresponding to the operation amount of the accelerator pedal 2. The clutch engagement pressure of the shift-side clutch (reverse clutch 9) rises at a constant gradient from the value at the end of switchback until a predetermined time Ts (for example, several seconds) elapses, and complete engagement at once at the elapse of the predetermined time Ts. Is done. That is, even in the starting process, the half clutch is maintained until the predetermined time Ts elapses, and the acceleration shock is reduced.

In the starting process, TRC control is also performed. In the case where the drive wheel 5 slips even when the acceleration of the half clutch is suppressed, a predetermined pressure Po is detected while the clutch pressure Pcl is being detected.
When the clutch pressure is restored, the clutch pressure Pcl is gradually reduced by an amount corresponding to the integral value of the region where the acceleration acc exceeds the threshold value A2mode on the positive side. For this reason,
By the TRC control, the driving force of the driving wheel 5 converges to a substantially equilibrium point where the driving force balances with the road surface resistance (see FIG. 7).

This embodiment has the following effects. (1) During the switchback, the shift-side clutch is a half-clutch, so that the braking force of the drive wheels 5 is weakened, and switchback in which the forklift is smoothly braked can be realized. Further, since the braking force of the driving wheel 5 is weakened, the deceleration shock of the vehicle during the switchback can be reduced, and the locking of the driving wheel 5 hardly occurs.

(2) Further, during switchback, since the engine speed is suppressed to the predetermined upper limit value NEsb or less, the braking force applied to the drive wheels 5 is further reduced, and the forklift is more smoothly braked. Can be realized. Further, since the braking force of the driving wheel 5 is weakened, the deceleration shock of the vehicle at the time of switchback can be effectively reduced, and the locking of the driving wheel 5 is further unlikely to occur.

(3) During switchback, the clutch engagement pressure Phr of the shift-side clutch is set in consideration of the load so that the larger the load, the larger the load. The load is set in consideration of the load so that the larger the weight, the larger the value. Therefore, during switchback, almost the same feeling of deceleration can be always obtained without being affected by the presence or absence of the load of the forklift or the difference in the load.

(4) When the lock of the driving wheel 5 is detected during the switchback, a kind of ABS control for weakening the clutch engagement pressure of the shift side clutch is adopted, so that the locking of the driving wheel 5 during the switchback deceleration is almost completed. It can be reliably prevented. For example, it is possible to avoid tire marks (tire marks) on the floor of the factory due to switchback.

(5) Since the clutch engagement pressure Pcl at the time of return when lock of the drive wheel 5 is no longer detected is gradually reduced so that the drive force of the drive wheel 5 converges to the equilibrium point with the road surface resistance. In addition, it is possible to avoid a situation where the deceleration is unnecessarily weakened due to the adoption of the ABS control.

(6) The clutch engagement pressure Pcl at the time of return when the lock of the drive wheel 5 is no longer detected is gradually reduced at a reduction rate corresponding to the integral value in a region where the acceleration acc exceeds the set value A1mode on the negative side. Therefore, the driving force of the driving wheel 5 can be quickly converged to the equilibrium point with the road surface resistance, and the frequency of occurrence of lock of the driving wheel 5 can be reduced more effectively.

(7) When slippage of the drive wheels 5 is detected during the starting process after the switchback is completed, TRC control for weakening the clutch engagement pressure of the shift side clutch is adopted.
It is possible to make it difficult for the drive wheels to slip in the starting process after the switchback is completed.

(8) Predetermined time T after switchback is completed
During s, the shift clutch is kept half-clutched,
After the switchback, a smooth start with a small acceleration shock can be realized.

(9) During the execution of the TRC control, the engine speed is suppressed to the idling speed, so that the slip of the drive wheels 5 can be effectively prevented. If an attempt is made to reduce the engine speed only during tire slip detection by the TRC control, the timing cannot be properly adjusted due to a delay in response of the engine speed. However, in the present embodiment, the engine speed is maintained low while intgB> 0, which is likely to cause tire slip, is satisfied. Therefore, there is no fear of timing inconsistency due to a response delay of the engine speed.
Therefore, when the clutch engagement pressure is released, the engine speed is always kept low, and the effect of suppressing slippage is enhanced.

(10) Even in the starting process after the end of switchback, the initial clutch pressure Pcl is set to a larger value as the load is heavier, so that the starting acceleration is not affected by the presence or absence of the load and the difference in the load. Can be stable.

(11) Since ΔA in which the acceleration Δacc is numerically limited to a value equal to or less than the predetermined value α is adopted, ABS control or T
In the RC control, it is possible to avoid a sudden change in the clutch pressure Pcl at the time of return. For this reason, the driving force of the driving wheels 5 can be more easily converged to the equilibrium point with the road surface resistance.

(12) Tire lock and tire slip are detected when the rotational acceleration of the drive wheel 5 becomes a value that cannot be obtained by deceleration or starting at the time of switchback of the forklift. Can be used. Therefore, although the ABS control and the TRC control are adopted, it is not necessary to provide a dedicated sensor for detecting the lock or slip of the drive wheel 5.

(Second Embodiment) Next, a second embodiment will be described. In this embodiment, the feeling of deceleration during switchback can be selected according to the driver's preference. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Particularly different points will be described in detail.

The structure of the forklift is the same as that of the first embodiment. The mode changeover switch 37 as a setting operation means is used to select a desired mode from three types of modes set in advance as a feeling of deceleration of the forklift at the time of switchback. There are three types of modes: hard, normal, and soft, and the strength of the sense of deceleration (assumed deceleration) set in this order increases. Since the feeling of deceleration is determined by the clutch engagement pressure of the shift side clutch, the clutch engagement pressure Phr according to the mode is set as well as the load in consideration of the load as the half clutch engagement pressure at the time of switchback.

The programs and some of the maps stored in the ROM 43 are different from those in the first embodiment. That is, the program of the switchback control is different from that of the first embodiment. The start control program is the same as in the first embodiment.

FIG. 13 shows a program of the switchback control, and a part of the program common to FIG. 8 of the first embodiment is partially omitted. The SB engine speed control routine is the same as that of the first embodiment (FIG. 9). The SB clutch pressure control routine differs from the first embodiment in that a mode is considered in determining the clutch engagement pressure Phr, and the routine shown in FIG. 14 is employed. A map M5 shown in FIG. 15 is used in the processing of FIG. 14 when determining the clutch engagement pressure Phr in consideration of the mode, and is stored in the ROM 43.

First, the switchback control program shown in FIG. 13 will be described. The clutch engagement pressure Phr of the shift side clutch is determined in consideration of two factors, load and mode, so that deceleration according to the set mode is obtained during switchback. For this reason, the estimated time Tsb required from the switchback operation time to the vehicle stop differs depending on the setting mode, so the estimated time Tsb is calculated for each mode.

S10 and S20 have the same contents as those in FIG. In other words, only when the switchback operation is performed once, the expected time Tsb corresponding to the setting mode is calculated in S700 to S740.

In S700, it is determined whether or not the mode is the hard mode. If the mode is the hard mode, an expected time Tsb corresponding to the hard mode is calculated in S720. The acceleration (deceleration) of the vehicle during switchback is determined from the clutch engagement pressure Phr (see map M5 in FIG. 15) according to the setting mode.
For example, assumed accelerations (decelerations) in the hard, normal, and software modes are set to αh, αn, and αs.
The expected time Tsb in the hard mode is given by the formula Tsb = Vst
/ Αh. On the other hand, if not in the hard mode, the process proceeds to S710.

In S710, it is determined whether the mode is the soft mode. If the mode is the soft mode, an expected time Tsb corresponding to the soft mode is calculated in S730. That is, it is calculated from the equation Tsb = Vst / αs. On the other hand, if the mode is not the soft mode (that is, if the mode is the normal mode), S
Proceed to 740.

At S740, an expected time Tsb according to the normal mode is calculated. That is, the equation Tsb = Vst / α
Calculate from n. Here, the deceleration is αh>αn> αs
Therefore, if the vehicle speed Vst is the same, the expected time Tsb becomes shorter in the order of hardware, normal, and software.

The processing after S40 is the same as that in FIG. That is, in S40, the count value SBcnt corresponding to the time Tsb is set in the SB counter. The SB counter has a time Tsb (count value SBcn) corresponding to the setting mode.
t) will be set.

The processing in S50 to S100 is the same as that in FIG. 8, the expected time Tsb has elapsed (S60), and the vehicle speed V
When the vehicle speed reaches the stop vehicle speed (V ≦ Vo) (S70), the routine shifts from the routine to the start control routine. On the other hand, after the elapse of the expected time Tsb in S60 (SBcnt = 0), the processes in S80 to S100 are executed until it is determined in S70 that the vehicle speed is at the stop vehicle speed (V ≦ Vo). That is, S8
0, the SB engine speed control (FIG. 9) is executed, and S90
To execute the SB clutch pressure control (FIG. 14). Also, S
At 100, the count value SBcnt is decremented.

Therefore, if the switchback operation for switching the shift lever 31 to the reverse direction is performed during traveling, the estimated time Tsb required for stopping the vehicle elapses, and the vehicle speed V is further reduced to the stop vehicle speed (V ≦ Vo). During this time, SB engine speed control (FIG. 9) and SB clutch pressure control (FIG. 14) are executed. The expected time Tsb at this time differs depending on the mode, but in any mode, the vehicle speed becomes the stopped vehicle speed after the time point when the vehicle is estimated to be stopped (SBcnt = 0) (Vcnt = 0).
Until ≤ Vo), the routines of Figs. 9 and 14 are executed.

Next, the SB clutch pressure control routine shown in FIG. 14 will be described. First, in S210, it is determined whether or not this routine has been executed for the first time. For example, the flag Fsb
Is switched to "1" from "0" is determined as the first time.

In the next S800, the clutch engagement pressure Phr according to the load and the mode is determined by referring to the map M5 (FIG. 15). As shown in FIG. 15, map lines H, N, and S are prepared for each mode of hardware, normal, and software, and the clutch engagement pressure Phr changes in accordance with the value of the load W in each map line. Using the map line corresponding to the mode selected by the mode changeover switch 37, the clutch engagement pressure Phr corresponding to the load W is obtained based on the map line. The clutch engagement pressure Phr is in the order of hard, normal, and soft.
Moreover, the larger the load W is, the larger the value is determined. The deceleration of the vehicle at the time of switchback is substantially determined by the clutch engagement pressure Phr.

At next S810, ABS control is executed. The ABS control is performed in steps S230 to S340 in FIG.
Corresponds to the processing of As shown in FIG. 6, in the ABS control,
The clutch engagement pressure Pcl is set to a predetermined value Po when a lock is detected in which the acceleration acc exceeds the lock determination threshold value Alock on the negative side.
Then, the clutch engagement pressure Pcl at the time of return after the lock is no longer detected is corrected to a value smaller than the previous value. This correction amount is basically proportional to the integral value (area of the hatched area) intgA of the region where the acceleration acc is lower than the set value A1mode, and the clutch engagement pressure Pcl at the time of return is calculated from the clutch engagement pressure Phr by the integral value intgA. Is obtained by subtracting a value corresponding to the ratio according to, and gradually decreases each time the clutch pressure is restored.

Here, the set value A1mode is set to a different value according to the mode, and takes a large value on the negative side in the order of hardware, normal, and software in accordance with each assumed deceleration in each mode. If the set value A1mode is A1h, A1n, and A1s in the order of hardware, normal, and software, Alock <A1
h <A1n <A1s <0. Therefore, if the acceleration acc is the same, the intgA takes a large value in the order of the soft, normal, and hard modes, and the reduction rate of the clutch engagement pressure Pcl at the time of the return increases in this mode. Therefore, in any mode, the clutch engagement pressure Pcl quickly converges to the equilibrium point. In FIG. 6, the acceleration acc converges to a value near the threshold Alock which does not exceed the threshold Alock.
Since the value converges to a value in the vicinity, the actual deceleration of the forklift is slightly smaller than the assumed deceleration A1mode corresponding to the mode by the amount by which the clutch engagement pressure is reduced by the ABS control.

As described in detail above, according to the present embodiment,
In addition to the effects (1) to (12) described in the first embodiment, the following effects can be further obtained. (13) By selecting a mode by operating the mode changeover switch 37, a feeling of deceleration during switchback according to the driver's preference can be obtained.

(14) Integral value intgA in ABS control
Set the value according to the mode to the set value A1mode that determines
Since the reduction rate for reducing the clutch engagement pressure Pcl at the time of return from the previous value is changed according to the mode, the driving force of the driving wheel 5 can be quickly converged to the equilibrium point with the road surface resistance in any mode. Can be. Therefore, the frequency of occurrence of lock of the drive wheels 5 can be effectively reduced.

(Third Embodiment) Next, a third embodiment will be described. In the present embodiment, when the SB clutch pressure control ends, the shift-side clutch is completely engaged from the half-clutch state at a stretch. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Particularly different points will be described in detail.

The construction of the forklift is the same as that of the first embodiment. Switchback control program (FIG. 8 or FIG. 13), SB engine speed control routine (FIG. 9), SB clutch pressure control routine (FIG. 10 or FIG. 1)
4) and start engine speed control routine (FIG. 11)
Is the same as in the first or second embodiment. The starting clutch pressure control routine is different from the above embodiments, and the present embodiment employs the routine shown in FIG. In each of the above embodiments, the clutch engagement pressure of the shift-side clutch is increased at a constant gradient from the initial clutch pressure Pclini until the time Tst from the start of the start control exceeds the predetermined time Ts. When the predetermined time Ts elapses, the clutch is completely engaged. On the other hand, the present embodiment employs a control in which the shift-side clutch is completely engaged at once at the same time as the start control is started.

Hereinafter, the starting clutch pressure control routine shown in FIG. 16 will be described. S910 and S920 are processes for obtaining an integral value intgA for determining a correction amount for correcting the clutch engagement pressure Pcl during the TRC control.
The processing contents are the same as those of S540 and S550 in the routine. S930, S940, and S970 correspond to S570, S580, and S610 in the routine of FIG.
And the processing contents are the same.

At S930, the acceleration acc is set to the threshold value A.
It is determined whether or not slip is exceeded (acc> Aslip). That is, it is determined whether tire slip has been detected. When tire slip is not detected, the process proceeds to S940, and when tire slip is detected, the process proceeds to S960.

In S940, it is determined whether or not the flag Ftrc = 1. That is, it is determined whether the mode is the TRC mode. If Ftrc is not 1, the complete engagement pressure Pc is adopted as the clutch pressure Pcl in S950.

At S990, the current value IP corresponding to the clutch pressure Pcl is applied to the shift side clutch valve.
Command cl. For this reason, when the switchback end determination is made and the control shifts to the start control, the shift-side clutch is completely engaged at a stretch.

On the other hand, when tire slip is detected in S930, the set pressure Po is adopted as the clutch pressure Pcl in S950. Then, in S990,
A current value IPcl corresponding to the clutch pressure Po is instructed to the shift side clutch valve. For this reason, when tire slip is detected, the clutch engagement pressure is reduced to the set pressure Po.

After entering the TRC mode, if the tire slip is not detected in S930, the clutch pressure is restored again. However, if it is determined in S940 that the TRC mode is set (Ftrc = 1), the clutch in restoration is returned in S970 and S980. Calculate the pressure Pcl.

In S970, the normalized value S of the integral value intgA is calculated.
er (0 ≦ Ser ≦ 1) is calculated. In S980, the clutch pressure Pcl is calculated from the equation Pcl = (1-Ser) · Pc. That is, the integral value intg with respect to the clutch pressure Pc
A clutch pressure Pcl subtracted by a ratio (= Ser) corresponding to A
Is calculated.

At S990, the clutch pressure Pcl = (1−Ser) · P is applied to the shift side clutch valve.
Command the current value IPcl corresponding to c. Therefore, TR
While the tire slip is detected in the C mode, the clutch pressure Pcl at the time of return gradually decreases, and the driving force of the drive wheels 5 balances with the road surface resistance and converges to the clutch pressure at an equilibrium point where tire slip does not barely occur. .

Therefore, after the switch-back operation, the estimated time Tsb elapses (S60), and the vehicle speed becomes the stop vehicle speed (V ≦ Vo) (S70), the SB engine speed control and the SB clutch pressure control are not performed. Is executed, the engine speed is suppressed to be lower than or equal to the upper limit value NEsb, and the shift side clutch is controlled to the half clutch. for that reason,
During switchback, the forklift decelerates smoothly. Further, when the lock of the drive wheel 5 is detected, the ABS control is executed, so that the drive wheel 5 is not locked.

Expected time T from detection of switchback operation
sb, and the vehicle speed V becomes the stop vehicle speed (V ≦ V
o) and the flag Fsb = 0, the switchback control ends, and the process shifts to the start control. At this time, the determination as to whether or not the vehicle speed V has reached the stop vehicle speed (V ≦ Vo) is made after the elapse of the estimated time Tsb (that is, after the vehicle stops), so that the drive wheels 5 during switchback are locked. In addition, an erroneous determination that the vehicle speed has stopped can be avoided.

Upon shifting to the start control, the shift side clutch is completely engaged at a stretch. At this time, the vehicle speed is almost 0, and the rotation speed on the input side of the shift-side clutch (turbine rotation speed of the torque converter) is proportional to the rotation speed on the output side (drive wheel rotation speed and reduction gear ratio). Are almost zero and the rotation difference is extremely small, so that even if the clutch is completely engaged at once, no shock is generated. In the start control, the engine speed is controlled to a value corresponding to the operation amount of the accelerator pedal 2.

In the starting process, TRC control is also performed. When the drive wheel 5 slips, the clutch pressure Pcl is reduced to the set pressure Po during slip detection, and when the clutch pressure is restored, the acceleration acc is reduced to the threshold A2mode. At the reduction rate (= Ser) corresponding to the integral value intgA in the region exceeding the positive side, the complete engagement pressure P
By subtracting from c, the clutch pressure Pcl is gradually reduced. Therefore, the driving force of the driving wheel 5 converges to a substantially equilibrium point where the driving force of the driving wheel 5 is balanced with the road surface resistance by the TRC control. Therefore, the driving wheels 5 do not slip during the starting process after the switchback is completed.

According to this embodiment, when applied to the first embodiment, the above (1) to (7), (9),
The same effects as (11) and (12) are obtained, and when applied to the second embodiment, (13) and (1)
The same effects as in 4) are obtained, and the following effects are also obtained.

(15) When the switchback control is completed and the control shifts to the start control, the shift-side clutch is completely engaged from the half-clutch state at once, so that the clutch is maintained in the half-clutch state as compared with the above embodiments. Since the time is short, the wear speed of the clutches 8 and 9 can be reduced and the life thereof can be extended. Also, when the vehicle speed is stopped at which the shift-side clutch is completely engaged, since the rotation difference between the input side and the output side of the shift-side clutch is small, even if the shift-side clutch is completely engaged from the half-clutch state at once, a large shock is generated. Does not happen.

The embodiment is not limited to the above, and can be implemented in the following modes. It is also possible to adopt a method in which the clutch on the shift side is switched back with full engagement, and only the engine speed during switchback deceleration is reduced. Even if the engine speed is kept low, the deceleration during switchback of the forklift can be reduced.

The upper limit of the engine speed during switchback deceleration may be set as the idle speed. That is, a constant value may be given to the engine speed during switchback deceleration. Of course, the constant value is not limited to the idle speed.

The section in which the engine speed is limited to the upper limit value or less is not limited to the section from the time of the switchback operation to the time when the stop vehicle speed is reached. This SB engine speed control is employed only in a deceleration section that is equal to or higher than the set vehicle speed that is higher than the stop vehicle speed. In short, it is sufficient that the section is effective to suppress the deceleration shock at the time of switchback small.
For example, the configuration may be such that the upper limit of the engine speed is limited only in the deceleration section of 8 km / h or more.

A control method may be adopted in which the shift-side clutch is set to a half clutch during switchback, and a value corresponding to the operation amount of the accelerator pedal 23 is used as the engine speed. The deceleration of the forklift during switchback can be reduced by simply changing the shift side clutch to a half clutch.

The section in which the shift-side clutch is half-clutched during the switchback is not limited to the section from the time of the switchback operation until the stop vehicle speed is reached. This SB clutch pressure control can be adopted only in a deceleration section equal to or higher than the set vehicle speed higher than the stop vehicle speed. In short, any section that is effective to reduce the deceleration shock at the time of switchback may be used. For example, the shift side clutch may be a half clutch only in a deceleration section of 8 km / h or more.

In the above embodiments, the recognition means for engine control, the recognition means for clutch control, the recognition means for lock prevention control, and the recognition means for slip prevention control
Although common means for checking the conditions when sb = 0 is used, the conditions may be set so that different times are recognized. The section in which the engine speed is limited to the upper limit or less during switchback may be different from the section in which the shift-side clutch is half-clutched during switchback. It is assumed that the section is equal to or higher than the set vehicle speed, and the half-clutch control of the clutch is a section until the stop vehicle speed is reached. Also,
A section in which the shift-side clutch is half-clutched during switchback and a section in which ABS control is performed during switchback may be different. Further, the execution sections of the ABS control and the TRC control may overlap, for example, in a stopped vehicle speed range. A
Even if the sections where the BS control and the TRC control are performed overlap, there is no problem as long as the ABS control is executed when the driving wheels are locked and the TRC control is executed when the driving wheels slip.

The ABS control during switchback deceleration can be eliminated. In the configuration in which the shift-side clutch is completely engaged during switchback deceleration, a configuration that employs ABS control can be implemented. If the ABS control is adopted, the lock of the drive wheel 5 during the switchback can be prevented. In addition, if a method of gradually reducing the clutch engagement pressure Pcl in the ABS control is adopted, the deceleration can be reduced to such a degree that the driving wheels 5 are not locked. Further, in this configuration, a method of setting an upper limit to the engine speed during switchback deceleration may be adopted to enhance the effect of suppressing the deceleration shock and the lock of the drive wheels 5.

The clutch engagement pressure P in ABS control
The method of calculating the correction of cl is not limited to the method using the integrated value of acceleration. In short, it is only necessary that the clutch engagement pressure Pcl gradually decreases. In particular, if the reduction rate of the clutch engagement pressure Pcl gradually decreases, the driving force of the driving wheels 5 can be converged to an equilibrium point that balances the road surface resistance. For example, control for gradually reducing the clutch engagement pressure at a preset reduction rate may be employed.

The lock threshold Alo is used as a correction threshold used for calculating an integral value in ABS control.
A configuration using ck may be used. The method for recognizing the control end time of the braking mitigation control performed during the switchback is not limited to the above embodiments. Either a method of determining and recognizing that the detected vehicle speed has reached the stop vehicle speed (set vehicle speed) or a method of determining and recognizing that the expected time Tsb required for stopping has elapsed is adopted. can do. For example, in the former case, if a vehicle speed detecting means (vehicle speed sensor) for detecting the rotation of the driven wheel is used, it is possible to avoid erroneously determining that the vehicle is stopped when the drive wheel is locked. Also, other recognition methods can be adopted. For example, it is also possible to adopt a configuration in which the time when the acceleration switches from negative (deceleration) to positive (acceleration) (vehicle stop time) is the control end time. Further, the input-side rotation speed of the shift-side clutch detected by the turbine speed sensor is compared with the output-side rotation speed of the shift-side clutch estimated from the detection value of the vehicle speed sensor 17 in consideration of the reduction ratio. A method of recognizing when the rotation difference between the output side and the output side falls within a certain range as the control end time may be adopted.

In the second embodiment, it is possible to use a setting operation means such as a volume which can continuously and variably set the deceleration feeling strength (mode). ○ The transmission may be a dry clutch type.

○ Industrial vehicles are not limited to forklifts.
The present invention may be applied to other industrial vehicles that can perform switchback operation, such as a shovel loader. The technical ideas other than the claims that can be grasped from the embodiment and other examples are described below.

(1) The recognition means (at least one of engine control, clutch control, and lock prevention control) according to any one of claims 1, 3 to 6, and 9 to 14, After the switch-back operation is detected by the detecting means, the control end time is recognized at a predetermined time in a section where the vehicle is at or below the set vehicle speed. With this configuration, the braking mitigation control is performed at least in a deceleration section exceeding the set vehicle speed, and the braking mitigation control is ended at a predetermined time equal to or lower than the set vehicle speed.

(2) In any one of claims 1, 3 to 6, and 9 to 14, the recognition means (indicating at least one of engine control, clutch control, and lock prevention control) may include When the vehicle speed becomes equal to or lower than the set vehicle speed during deceleration of the vehicle after the switchback operation is detected by the detection means, the control end time is recognized. In this configuration, the braking mitigation control is performed in a deceleration section exceeding the set vehicle speed.

(3) In the technical ideas of the above (1) and (2), the vehicle speed below the set vehicle speed is a stop vehicle speed. The stop vehicle speed refers to a vehicle speed range equal to or lower than the vehicle speed Vo (V ≦ Vo) in the embodiment. With this configuration, the brake relaxation control is continued at least until the stop vehicle speed is reached during switchback, and a smoother switchback can be realized.

(4) According to claim 14, load detecting means (22) for detecting the weight of the load loaded on the vehicle is provided,
The starting acceleration control means controls the shift side clutch to a clutch engagement pressure of a half clutch in consideration of a load based on a detection value of the load detection means. With this configuration, a smooth start can be realized after the switchback is completed.

(5) The braking mitigation control according to any one of claims 1 to 14, wherein the recognition means recognizes that the control end time has come within a section where the vehicle after the switchback operation is detected is in a stopped vehicle speed state. In the starting process after the end of the starting, the starting acceleration control means (1) that controls the control valve so that the shift side clutch becomes a half clutch.
0, 11, 41). According to this configuration, in addition to the effects of the invention according to any one of the first to fourteenth aspects, a smooth start with a small acceleration shock can be realized in the start process after the switchback is completed.

(6) In the fourteenth aspect, the slip prevention control means sets the clutch engagement pressure for returning after weakening during detection of the slip of the drive wheel to an equilibrium point of the drive force of the drive wheel with the road surface resistance. Control is performed so as to gradually decrease so as to converge. In this case, the acceleration is not unnecessarily reduced.

(7) In the technical idea of the above (6), the slip detecting means detects a rotational acceleration of the drive wheel, and when it is determined that the rotational acceleration exceeds a threshold value, the drive wheel slips. Wherein the slip prevention control means reduces the clutch engagement pressure at the time of return at a reduction rate corresponding to an integral value of a portion where the rotational acceleration exceeds a correction threshold value for slip measures. . in this case,
The driving force of the driving wheels can be quickly converged to an equilibrium point with the road surface resistance.

[0173]

As described above in detail, according to the first and second aspects of the present invention, during switchback deceleration, the engine speed is suppressed to a value lower than the preset upper limit value.
A switchback that can be braked smoothly can be realized.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, the engine speed is controlled to be equal to or less than a preset upper limit value during switchback until the vehicle reaches the stop vehicle speed. A switchback in which the vehicle is braked more smoothly can be realized.

According to the third to eighth aspects of the present invention, the shift-side clutch is a half-clutch during switchback deceleration, so that switchback can be realized in which the vehicle is smoothly braked.

According to the invention of claim 4, in addition to the effect of the invention of claim 3, the shift-side clutch is controlled to the clutch engagement pressure in consideration of the influence of the load so as to obtain a predetermined deceleration feeling. Regardless of the presence or absence of a load on the industrial vehicle and the difference in load, the feeling of deceleration during switchback deceleration can always be made substantially the same.

According to the invention of claim 5, claim 3 or 4
In addition to the effects of the invention, during switchback deceleration, the clutch engagement pressure is controlled according to the deceleration intensity set by the setting operation means. Can be obtained.

According to the sixth aspect of the invention, in addition to the effect of the third aspect of the invention, the engine speed is suppressed to a predetermined upper limit or less during switchback deceleration. Thus, switchback in which the vehicle is more smoothly braked can be realized.

According to the seventh aspect of the invention, in addition to the effect of the third aspect of the invention, when the control end time comes, the shift-side clutch is brought into a half-clutch state in a section where the vehicle is at a stop vehicle speed. Since the clutch is completely engaged at a stretch, shock is unlikely to occur, and it contributes to prevention of early wear of the clutch.

According to the eighth aspect of the invention, in addition to the effects of any one of the third to seventh aspects, during the switchback, the shift side clutch is maintained at the half clutch until the vehicle reaches the stop vehicle speed. Therefore, a switchback in which the vehicle is more smoothly braked can be realized.

According to the ninth to thirteenth aspects of the present invention, during switchback deceleration, when lock of the drive wheel is detected, the clutch engagement pressure of the shift side clutch is weakened, so that the lock of the drive wheel hardly occurs, and the vehicle is not decelerated. A switchback that can be braked smoothly can be realized.

According to the tenth aspect, in addition to the effect of the ninth aspect, during switchback deceleration, the engine speed is suppressed to a predetermined upper limit or less, so that the braking force of the vehicle is reduced. As a result, switchback in which the vehicle is braked more smoothly can be realized.

According to the eleventh aspect of the present invention, in addition to the effects of the ninth or tenth aspect, during switchback deceleration, the shift side clutch is half-engaged to reduce the braking force of the vehicle. Can be realized more smoothly.

According to the twelfth aspect, the ninth to the ninth aspects
In addition to the effect of the present invention, when the lock of the drive wheel is no longer detected and the clutch engagement pressure is restored, the drive force of the drive wheel is gradually reduced to an equilibrium point with the road surface resistance. Since the clutch engagement pressure is reduced at the same time, it is possible to avoid a situation where the deceleration is unnecessarily weakened excessively due to the drive wheel lock prevention control.

According to the thirteenth aspect, in addition to the effect of the twelfth aspect, when lock of the drive wheel is detected,
Since the clutch engagement pressure is reduced at a reduction rate corresponding to the integral value of the region where the rotation deceleration of the drive wheel exceeds the correction threshold, the drive force of the drive wheel quickly converges to the equilibrium point with the road surface resistance. Thus, the frequency of occurrence of lock of the driving wheels can be reduced.

According to the fourteenth aspect, claims 9-1
According to the effects of the invention of any one of (3), it is possible to make it difficult to lock the driving wheels during the switchback deceleration,
In addition, in the starting process after the end of the switchback, it is possible to make it difficult for the driving wheels to slip.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a forklift according to a first embodiment.

FIG. 2 is a map diagram showing a relationship between a load and an engine speed upper limit value.

FIG. 3 is a map diagram showing a relationship between an accelerator opening and a target engine speed.

FIG. 4 is a map diagram showing a relationship between a load and a clutch engagement pressure.

FIG. 5 is a map diagram showing a relationship between a load and an initial clutch engagement pressure.

FIG. 6 is a graph for explaining ABS control.

FIG. 7 is a graph for explaining switchback control.

FIG. 8 is a flowchart showing switchback control.

FIG. 9 is a flowchart illustrating an SB engine speed control routine.

FIG. 10 is a flowchart showing an SB clutch pressure control routine.

FIG. 11 is a flowchart showing a start engine speed control routine.

FIG. 12 is a flowchart showing a starting clutch pressure control routine.

FIG. 13 is a flowchart illustrating a part of switchback control according to the second embodiment;

FIG. 14 is a flowchart showing an SB clutch pressure control routine.

FIG. 15 is a map diagram for obtaining a clutch engagement pressure according to a load and a mode.

FIG. 16 is a flowchart illustrating a starting clutch pressure control routine according to a third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Torque converter, 3 ... Transmission, 5
... drive wheels, 7 ... throttle actuators constituting engine speed control means, 8 ... forward clutch, 9 ... reverse clutch, 8a, 9a ... pressure receiving chamber, 10 ... clutch control means, lock prevention control means and slip prevention control means. A forward clutch valve as a control valve
1: a reverse clutch valve which constitutes clutch control means, lock prevention control means and slip prevention control means and serves as a control valve; 17: engine control recognition means, clutch control recognition means, lock prevention control recognition means, slip prevention A vehicle speed sensor that constitutes an application recognition means, a stop recognition means, a lock detection means and a slip detection means, 22 a load sensor as load detection means, 31 a shift lever as shift operation means, 32 a shift which constitutes operation detection means Switch, 37: Mode changeover switch as setting operation means, 41: Operation detection means, engine control recognition means, clutch control recognition means, lock prevention control recognition means, slip prevention control recognition means, stop recognition means, engine Speed control means, clutch control means, lock prevention control means, lock detection Means, slip prevention control means and control device constituting slip detection means, 42... Operation detection means, engine control recognition means, clutch control recognition means, lock prevention control recognition means, slip prevention control recognition means, stop recognition Means, engine speed control means, clutch control means, lock prevention control means, lock detection means,
CPU constituting slip prevention control means and slip detection means.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (reference) F02D 29/00 F02D 29/00 FH 29/02 341 29/02 341 F term (reference) 3D041 AA33 AA47 AB07 AC02 AC16 AD02 AD10 AD31 AD39 AD41 AD47 AD50 AD51 AD53 AE03 AE04 AE30 AE39 AF01 AF09 3F333 AA02 DA10 DB10 FA16 FA31 FD20 FE10 3G093 AA08 BA01 BA14 CB00 DA01 DA06 DB00 DB05 DB11 DB15 DB18 DB21 DB23 DB24 FA03 EA03 FA07 FA07 FA07 FB02 FB03 FB05

Claims (14)

[Claims] 1. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to an output shaft via a torque converter, and adjusting the connection by increasing or decreasing the oil pressure in a pressure receiving chamber of each clutch. A control valve for switching the transmission to a forward / neutral / reverse state; and detecting a switchback operation for switching the shift operating means from forward to reverse or from reverse to forward while the vehicle is traveling. Operation detecting means for performing the control, engine control recognizing means for recognizing that the control end time for ending the braking mitigation control performed to alleviate the braking at the time of switchback has been reached, and A section from the control start time to the end of the control by the engine control recognizing means is recognized as the braking mitigation control. Switchback control apparatus for an industrial vehicle and an engine speed control means for controlling the emissions rotational speed below a preset limit. 2. The engine control recognition means is a stop recognition means for estimating or detecting that the vehicle has reached a stop vehicle speed after a switchback operation detected by the operation detection means and recognizing a control end time. The switchback control device for an industrial vehicle according to claim 1. 3. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to an output shaft via a torque converter, and adjusting the connection by increasing or decreasing the hydraulic pressure in a pressure receiving chamber of each clutch. A control valve for switching the transmission to a forward / neutral / reverse state; and detecting a switchback operation for switching the shift operating means from forward to reverse or from reverse to forward while the vehicle is traveling. Operation detecting means for performing the control, clutch control recognizing means for recognizing that the control end time for ending the braking mitigation control performed to alleviate the braking at the time of switchback has been reached, and The section from the control start time until the clutch control recognizing means recognizes that the control end time has been reached is defined as the braking mitigation control. Switchback control device for industrial vehicle a shift clutch and a clutch control means for controlling said control valve so as to half-clutch. 4. A load detecting means for detecting a load amount of a load loaded on the vehicle, wherein the clutch control means detects the deceleration of the vehicle at the time of switchback by the load detecting means so as to be hardly affected by the load. 4. The switchback control device for an industrial vehicle according to claim 3, wherein the control valve of the shift-side clutch is controlled such that the larger the load is, the larger the clutch engagement pressure is, in consideration of the detected load. 5. A setting operation means for setting a deceleration intensity of the vehicle at the time of switchback, wherein the clutch control means sets a clutch engagement pressure of the shift-side clutch by the setting operation means. The switchback control device for an industrial vehicle according to any one of claims 2 to 4, wherein the control valve is controlled such that the control valve has a value corresponding to a set deceleration feeling. 6. The switchback control device for an industrial vehicle according to claim 3, further comprising the engine control recognition unit and the engine speed control unit according to claim 1 or 2. . 7. The control end time recognized by the clutch control recognition means is set in a section where the vehicle is at a stop vehicle speed, and the clutch control means sets the clutch control recognition means to the control end time. The switchback control device for an industrial vehicle according to any one of claims 3 to 6, wherein the control valve is controlled so that the shift-side clutch is completely engaged when the shift valve is recognized. 8. The stop recognizing means is a stop recognizing means for estimating or detecting that the vehicle has reached a stop vehicle speed after the switchback operation detected by the operation detecting means and recognizing a control end time. The switchback control device for an industrial vehicle according to any one of claims 3 to 7. 9. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to an output shaft via a torque converter, and adjusting the connection by increasing or decreasing the oil pressure in a pressure receiving chamber of each clutch. A control valve for switching the transmission to a forward / neutral / reverse state; and detecting a switchback operation for switching the shift operating means from forward to reverse or from reverse to forward while the vehicle is traveling. Operation detecting means for performing lock-reducing control, and recognizing means for lock prevention control for recognizing that control end time for ending the braking mitigation control performed to alleviate braking at the time of switchback has been reached, and detecting lock of drive wheels. A lock detection unit, and a lock end control recognition unit that recognizes that the control end time has come from a control start time after the switchback operation detection time. In a section until the lock release control is performed, the lock prevention means controls the control valve so as to weaken the clutch engagement pressure of the shift-side clutch when the lock of the drive wheel is detected by the lock detection means. And a switchback control device for an industrial vehicle. 10. A switchback control device for an industrial vehicle according to claim 9, comprising the engine control recognition means and the engine speed control means according to claim 1 or 2. 11. The switchback control device for an industrial vehicle according to claim 9, further comprising the clutch control recognizing unit and the clutch control unit according to any one of claims 3 to 8. 12. The lock prevention control means sets a clutch engagement pressure at the time of return after weakening during lock detection of a drive wheel.
The switchback control device for an industrial vehicle according to any one of claims 9 to 11, wherein control is performed such that the driving force of the driving wheels is gradually reduced so as to converge to a point of equilibrium with the road surface resistance. 13. The lock detecting means detects a rotation deceleration of a driving wheel, and detects that the driving wheel is locked when it is determined that the rotation deceleration exceeds a preset locking threshold value. The lock prevention control means controls the clutch engagement pressure at the time of return to gradually decrease at a reduction rate according to an integral value of a portion where the rotation deceleration of the drive wheel exceeds the correction threshold value. 13. The switchback control device for an industrial vehicle according to claim 12, wherein: 14. An anti-slip control recognizing means for recognizing that a control start timing for starting anti-slip control implemented to prevent slip of a drive wheel in a starting process after switchback has come, and a drive wheel. After the slip detection means for detecting the slip of the drive wheel, when the slip detection means detects the slip of the drive wheels after the control start timing is recognized by the slip prevention control recognition means, 10. An anti-slip control means for controlling the control valve so as to reduce clutch engagement pressure.
The switchback control device for an industrial vehicle according to any one of claims 13 to 13.