JP2001116071A - Cargo handling/travel control device for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve stability of a vehicle at cargo handling travel time by automatically controlling a speed at that time. SOLUTION: Output of an engine 1 is transmitted to a driving wheel 5a via a transmission 3 having hydraulic clutches 8, 9. At ordinary travel time, an advancing side clutch is held in a completely engaged state, and the engine 1 is controlled at an engine speed corresponding to a manipulated variable of an accelerator pedal 25. At cargo handling travel time, the engine 1 is controlled at an engine speed corresponding to cargo handling work, the clutches are held in a half clutch state, and engaging pressure of the clutches is controlled so as to become a vehicle sped corresponding to the manipulated variable of the accelerator pedal 25. A CPU 42 controls a forward clutch valve 10 and a reverse clutch valve 11 so as to obtain braking force by simultaneous engagement of the forward clutch 8 and the reverse clutch 9 when a brake pedal 27 is operated at cargo handling travel time. The CPU 42 controls so that the braking force becomes a prescribed upper limit value or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo handling and traveling control device for an industrial vehicle such as a forklift, and more particularly, to an industrial vehicle in which a driving source for traveling and a driving source for cargo handling are shared by one engine. And a travel control device.

[0002]

2. Description of the Related Art Conventionally, in an industrial vehicle such as a forklift, one driving engine is used as both a driving source for traveling and a driving source for cargo handling. For example, in a forklift equipped with a torque converter, the output of an engine is transmitted to drive wheels via a torque converter and a clutch, and a hydraulic pump for cargo handling is driven by the engine and a loading cylinder such as a lift cylinder is operated via a hydraulic circuit. It is made to let.

In order to make a forklift travel at a very low speed, the engine speed is reduced, and when the fork is raised, the engine speed is increased. However, when traveling at a very low speed while raising the fork, it is necessary to operate the clutch or the inching pedal while pressing the accelerator pedal to bring the clutch into a half-clutch state, which makes driving operation difficult and requires skill.

[0004] To solve the above-mentioned inconvenience, Japanese Patent Application Laid-Open
JP-A-151974 discloses a transmission including a torque converter and a hydraulic forward clutch and a reverse clutch.
Discharge pressure oil of the clutch pump is supplied to the pressure receiving chamber of the forward clutch, and the clutch control valve for increasing / decreasing forward / reverse braking which stops and increases / decreases the oil pressure, and the pressure receiving chamber of the reverse clutch for discharging hydraulic pressure of the clutch pump are provided. There is disclosed an apparatus provided with a clutch control valve for increasing / decreasing reverse movement and braking during forward movement, which supplies and stops the hydraulic pressure and increases / decreases the hydraulic pressure. And
The control means sets the engine speed based on the operation amount of the cargo handling lever when judging that it is a single cargo operation, and sets the engine speed based on the operation amount of the accelerator pedal when judging that it is a single operation (normal running). When the control means determines that the operation is both cargo handling and running (cargo handling), the control means sets the engine speed based on the operation amount of the cargo handling lever, and increases / decreases the hydraulic pressure of the pressure receiving chamber of the traveling clutch by using the clutch control valve. Acceleration / deceleration control is performed so that the vehicle speed corresponds to the operation amount. With this device, in the state of both cargo handling and running, the operator can run the forklift at a desired running speed only by operating the accelerator pedal.

[0005]

Since the center of gravity of the vehicle increases during cargo handling, running or braking in the same state as during normal traveling may reduce the stability of the vehicle.
However, Japanese Patent Application Laid-Open No. 10-151974 does not disclose any matters relating to the stability of the vehicle at the time of transition from normal traveling to cargo handling traveling or during cargo handling traveling.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to automatically perform speed control during loading / unloading traveling.
Another object of the present invention is to provide a cargo handling and travel control device for an industrial vehicle that can improve the stability of the vehicle during cargo handling travel.

[0007]

According to a first aspect of the present invention, there is provided a transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to drive wheels via a torque converter. A control valve for adjusting the engagement state by increasing or decreasing the oil pressure in the pressure receiving chamber of each clutch, accelerator operation amount detection means for detecting the operation amount of accelerator operation means, target vehicle speed setting means for the accelerator operation amount,
Target engine speed setting means for the accelerator operation amount, vehicle speed detection means for detecting the traveling speed of the vehicle, a pump for cargo handling driven by the engine, and an operation amount of the cargo handling operation means operated for performing cargo handling work Operating amount detecting means for detecting the load, a target engine speed setting means for the operating amount of the cargo handling, and determining whether the vehicle is traveling normally or not based on the detection signals of the accelerator operating amount detecting means and the operating amount detecting means. Means for controlling the target engine speed corresponding to the operation amount of the accelerator operating means by setting the clutch on the traveling side to a completely engaged state when the determining means determines that the vehicle is traveling normally; In this case, it is assumed that the target engine speed is controlled based on the operation amount of the cargo handling operation means, and the clutch on the traveling side is set to the half clutch state. Wherein it relates to handling and running controller for the industrial vehicle and a control means for controlling the engagement pressure of the clutch so that the target vehicle speed corresponding to the operation amount of the accelerator operation means.

In order to achieve the above object, the invention according to the first aspect includes a brake operating means, wherein the control means increases a braking force when the brake operating means is operated during cargo handling. Braking is performed so as to be less than the value.

According to a second aspect of the present invention, in the first aspect of the invention, the control means controls the two control valves so as to obtain the braking force by simultaneous engagement of the forward clutch and the reverse clutch. .

According to a third aspect of the present invention, in the first aspect of the present invention, a hydraulic brake clutch is incorporated in the transmission, and the control means controls the pressure receiving chamber of the brake clutch during the braking. The control valve that adjusts the engagement state by increasing or decreasing the hydraulic pressure of the motor is controlled.

According to a fourth aspect of the present invention, in the second or third aspect of the present invention, the control means applies a braking pressure equal to or less than a preset upper limit corresponding to the lift and weight of the load. The control valve is controlled as described above.

According to a fifth aspect of the present invention, the control means controls the engine speed to be equal to or less than an upper limit set in advance in accordance with the vehicle speed and the weight of the load when the weight of the load is equal to or more than a predetermined value. Control.

[0013] In the invention described in claim 6, the control means controls the vehicle speed during the cargo handling so that the vehicle speed is lower than the vehicle speed during the normal traveling. According to a seventh aspect of the present invention, in the sixth aspect of the invention, the vehicle speed has an upper limit set in accordance with a lift.

According to an eighth aspect of the present invention, in the sixth aspect of the invention, an upper limit is set for the vehicle speed in accordance with the lift and the weight of the load. According to the ninth aspect of the present invention, the control means does not completely engage the clutch on the traveling side and keeps the half-clutch state even when the determining means determines that the traveling is normal during the lifting of the load during the cargo handling travel. The target engine speed is set to the larger of the target engine speed corresponding to the operation amount of the accelerator operation means and the target engine speed set based on the operation amount of the cargo handling operation means, and the target engine speed is set to After the lifting of the load is stopped, the control is performed such that the clutch on the traveling side is completely engaged and the vehicle shifts to the normal traveling.

According to a tenth aspect of the present invention, there is provided a service brake which is operated in conjunction with the operation of the brake operating means, wherein the control means operates the accelerator when the brake operating means is operated during cargo handling. Regardless of the operation amount of the operation means, the target vehicle speed is set to 0 and the engagement pressure of the clutch on the traveling side is controlled.

According to the eleventh aspect of the present invention, when the vehicle speed is equal to or higher than a predetermined vehicle speed, the control means may control whether the accelerator operation amount detection means and the cargo operation amount detection means satisfy the condition of cargo handling travel. Control is performed so that control of normal traveling is continued without shifting to cargo handling traveling.

According to the twelfth aspect of the present invention, the eleventh aspect provides
In the invention described in (1), the predetermined vehicle speed is set to be the same as an upper limit vehicle speed during cargo handling traveling. According to the first aspect of the invention, whether the vehicle is traveling normally or not is determined by the determination unit based on the detection signals of the accelerator operation amount detection unit and the cargo operation amount detection unit. During normal traveling, the traveling clutch is held in a completely engaged state. Then, the engine is controlled to the target engine speed corresponding to the operation amount of the accelerator operation means, and the industrial vehicle runs at a vehicle speed corresponding to the operation amount of the accelerator operation means. At the time of cargo handling traveling, the engine is controlled to the target engine speed set based on the operation amount of the cargo handling operation means, and the required hydraulic pressure is supplied to the hydraulic circuit for cargo handling. Further, the engagement pressure of the clutch is controlled by the control means via the control valve so that the traveling side clutch is maintained in the half-clutch state and the vehicle speed corresponds to the operation amount of the accelerator operation means. When the brake operating means is operated during cargo handling traveling, braking is performed by a command from the control means in a state where the braking force is limited to be equal to or less than a predetermined upper limit value.

According to a second aspect of the present invention, in the first aspect of the invention, the braking force is controlled by simultaneous engagement of the forward clutch and the reverse clutch, that is, the clutch other than the forward clutch is also engaged. Thus, a braking action is obtained.

According to a third aspect of the present invention, in the first aspect of the invention, at the time of braking, the hydraulic pressure in the pressure receiving chamber of the hydraulic braking clutch incorporated in the transmission is controlled by a control valve according to a command from the control means. Is adjusted through.

According to a fourth aspect of the present invention, in the second or third aspect of the invention, the control valve is configured to apply a braking pressure equal to or less than a predetermined upper limit corresponding to the lift and weight of the load. Is controlled. Therefore, the stability of the vehicle can be improved without performing complicated processing for calculating the center of gravity of the vehicle.

According to the fifth aspect of the present invention, the functions of the forward clutch and the reverse clutch during normal traveling and during cargo handling traveling are basically the same as those of the first aspect.
However, when the cargo is traveling with the weight of the load equal to or more than the predetermined value, the control unit controls the engine speed to be equal to or less than the upper limit set in advance according to the vehicle speed and the weight of the load. Therefore, the stability of the vehicle while the load is rising is improved.

According to the sixth aspect of the present invention, the functions of the forward clutch and the reverse clutch during normal traveling and during cargo handling traveling are basically the same as those of the first aspect.
However, the vehicle speed is controlled so that the vehicle speed during the loading operation is lower than the vehicle speed during the normal operation. Therefore, the stability of the vehicle during cargo handling when the center of gravity of the vehicle is high is improved.

According to a seventh aspect of the present invention, in the invention of the sixth aspect, the upper limit of the vehicle speed is changed in accordance with the lift during the cargo handling. Therefore, the stability of the vehicle during cargo handling is further improved.

According to an eighth aspect of the present invention, in the sixth aspect of the invention, the upper limit of the vehicle speed is changed in accordance with the lift and the weight of the load during the loading and running. Therefore, the stability of the vehicle at the time of cargo handling travel is further improved as compared with the invention according to claim 7.

According to the ninth aspect of the present invention, the functions of the forward clutch and the reverse clutch during the normal traveling and the cargo handling traveling are basically the same as those of the first aspect.
However, during cargo handling traveling, the clutch on the traveling side is maintained in the half-clutch state without being completely engaged even if the determining means determines that the traveling is normal while the cargo is being lifted. Also,
The target engine speed is set to the larger of the target engine speed corresponding to the operation amount of the accelerator operation means and the target engine speed set based on the operation amount of the cargo handling operation means, and is set to the target engine speed. The engine is controlled by the control means. Then, after the lifting of the load is stopped, the traveling-side clutch is completely engaged, and the vehicle shifts to the normal traveling. Therefore, it is possible to avoid occurrence of a shock due to sudden engagement of the clutch while the load is rising.

According to the tenth aspect of the present invention, the functions of the forward clutch and the reverse clutch during the normal traveling and the cargo handling traveling are basically the same as those of the first aspect. When the brake operating means is operated, the service brake is operated at a braking pressure corresponding to the operation amount. When the brake operating means is operated during cargo handling traveling, the engagement pressure of the forward clutch is controlled to a value when the target vehicle speed is set to 0 regardless of the operation amount of the accelerator operating means. Therefore, the traveling side clutch pressure does not increase in order to maintain the vehicle speed against the braking force of the service brake, and the disadvantage that a larger force is required as the operation force of the brake operation means is solved.

In the eleventh aspect of the present invention, the functions of the forward clutch and the reverse clutch during the normal traveling and the cargo handling traveling are basically the same as those of the first aspect. When the vehicle speed is equal to or higher than the predetermined vehicle speed, even if the detection signals of the accelerator operation amount detection means and the cargo operation amount detection means satisfy the conditions of the cargo operation, the vehicle does not shift to the cargo operation and the control of the normal operation is continued. . Therefore, the shift to the cargo handling in which the center of gravity of the vehicle is increased is performed at a speed lower than the predetermined vehicle speed, and the stability of the vehicle is increased.

According to the twelfth aspect, in the eleventh aspect,
In the invention described in (1), the control is performed such that the speed is always lower than a predetermined vehicle speed during the loading operation. Therefore, the stability of the vehicle is further improved.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment in which the present invention is embodied in a forklift as an industrial vehicle will be described.
An embodiment will be described 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 5 having drive wheels 5a. The engine 1 is provided with an engine throttle actuator (hereinafter simply referred to as a throttle actuator) 7.
The throttle opening is adjusted by the operation of the engine 1
, That is, the rotation speed of the output shaft 1a of the engine 1 is adjusted.

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 engagement force can be adjusted by the oil pressure in pressure receiving chambers 8a and 9a. The configuration is such that the engagement force increases as the hydraulic pressure increases.

The forward clutch 8 and the reverse clutch 9 are controlled by the hydraulic pressure supplied through a forward clutch valve 10 and a reverse clutch valve 11 as control valves.
The oil pressure in a is adjusted. A pressure control proportional solenoid valve is used for the forward clutch valve 10 and the reverse clutch valve 11. In this embodiment, a proportional solenoid is fully opened when the amount of power to the solenoid is 0, and the opening decreases in proportion to the amount of power. A valve is used. That is, when the amount of power to the solenoids of the clutch valves 10 and 11 is 0, the hydraulic pressure in the pressure receiving chambers 8a and 9a is maximized, and the clutches 8 and 9 are completely engaged. Further, as the energization amount increases, the hydraulic pressure in the pressure receiving chambers 8a, 9a decreases, and the engagement pressure of the clutches 8, 9 decreases. When the energization amount exceeds a predetermined value, the clutches 8, 9 are disengaged. It will be in the combined state.

A parking brake 1 is provided on the output shaft 3b of the transmission 3.
2 are provided. The parking brake 12 includes a disk 12a that rotates integrally with the output shaft 3b, and a brake pad 12b that is provided so as not to rotate with respect to the output shaft 3b and to be movable in the thrust direction. The brake pad 12b is connected to the disk 12 by a spring (not shown).
a to generate an engagement pressure for braking, and the pressure receiving chamber 12 c
The braking state is released by the hydraulic pressure supplied to the vehicle. An electromagnetic valve is used as the brake valve 13.

In FIG. 1, the torque converter 2, the transmission 3, and the valves 10, 11, and 13 are shown independently, but 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 output shaft 1a of the engine 1 so as to be able to rotate integrally therewith. An engine speed sensor 15 comprising a magnetic pickup detects the rotation speed of the output shaft 1a. The engine speed sensor 15 outputs a pulse signal proportional to the speed of the output shaft 1a.

A gear 16 is provided on the input shaft 3a of the transmission 3 so as to be integrally rotatable. A housing of the transmission 3 is provided with a turbine sensor 17 as a turbine rotation speed detecting means. The turbine sensor 17 is constituted by a magnetic pickup and constitutes a rotation speed detecting means for detecting the rotation speed on the input side of each of the clutches 8 and 9. A gear 18 is provided on the output shaft 3 b of the transmission 3 so as to be integrally rotatable, and a vehicle speed sensor 19 is provided on a housing of the transmission 3. Vehicle speed sensor 1
Reference numeral 9 denotes a magnetic pickup, which constitutes a rotation speed detecting means for detecting the rotation speed on the output side of each of the clutches 8 and 9. The gears 16 and 18 constitute a part of the gear train for transmitting the rotation of the input shaft 3a to the output shaft 3b. Turbine sensor 1
7 outputs a pulse signal proportional to the rotation speed of the input shaft 3a, and the vehicle speed sensor 19 outputs a pulse signal proportional to the rotation speed of the output shaft 3b.

A lift cylinder 22 for raising and lowering the fork 21 and a tilt cylinder (not shown) for tilting the mast 23 are connected to a discharge side of a hydraulic pump 20 serving as a cargo handling pump driven by the engine 1 via a pipe (not shown). Connected. The lift cylinder 22 is provided with a pressure sensor 24 as a load detecting means for detecting the load of the fork 21. The pressure sensor 24 detects the oil pressure inside the lift cylinder 22 and
And outputs a detection signal corresponding to the loaded load.

An accelerator pedal 25 as an accelerator operating means, an inching pedal 26, and a brake pedal 27 are provided on the floor of the cab. The inching pedal 26 is used to bring the clutch into a half-clutch state when performing a slow operation of the forklift by manual operation while performing a cargo handling operation. Brake pedal 2
7, the brake pedal 27 operates independently of the inching pedal 26, but the inching pedal 2
When the driver 6 is operated, the inching pedal 26 and the brake pedal 27 can be interlocked halfway. That is, the inching pedal 26 is moved (operated) independently of the brake pedal 27 until the inching position is reached and at the inching position, but after the inching position, the brake pedal 27 moves integrally with the inching pedal 26. Has become.

The accelerator sensor 28 as an accelerator operation amount detecting means for detecting the operation amount of the accelerator pedal 25 is an accelerator sensor with an idle switch.
The accelerator sensor with idle switch is accelerator pedal 2
When the accelerator pedal 25 is not operated, an on signal is output. When the accelerator pedal 25 is operated, a detection signal proportional to the operation amount is output. An inching sensor with an idle switch is used as the inching sensor 29 for detecting the operation amount of the inching pedal 26. The inching sensor with an idle switch outputs an ON signal when the inching pedal 26 is not operated, and outputs a detection signal proportional to the operation amount when the inching pedal 26 is operated.

In the vicinity of the brake pedal 27, a brake switch 27a for detecting that the brake pedal 27 has been operated to the braking position is provided. Brake pedal 2
A brake operating force sensor (hereinafter, simply referred to as a brake sensor) 30 as a brake operating force detecting means for detecting an operating force acting on the brake pedal 27 is connected to 7. Two pistons are built in a cylinder constituting the brake sensor 30 with a chamber containing oil stored therebetween. A piston rod 30a connected to the brake pedal 27 protrudes from the first piston, and a spring is provided between the second piston and the bottom of the cylinder. The spring force is set so that the relationship between the depression force of the brake pedal 27 and the operation amount is substantially the same as when the service brake is provided. When the brake pedal 27 is operated, the indoor oil pressure rises according to the operation force, and a detection signal corresponding to the operation force (stepping force) is output from a pressure sensor (not shown) that detects the indoor oil pressure.

A shift lever 31 is provided at the front of the cab as forward / reverse switching operation means. The shift switch 32 that detects the position of the 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. .

In the driver's seat, a lift lever 33 and a tilt lever 3 as cargo handling operation means operated during cargo handling work.
4 are provided. The lift lever 33 is connected to a lift lever sensor 35 as a cargo handling operation amount detecting means. The lift lever sensor 35 is constituted by a stroke sensor, and outputs a detection signal proportional to the operation amount of the lift lever 33. The tilt lever 34 is provided with a tilt switch 36 as a cargo operation amount detection means.
The tilt switch 36 outputs an off signal when the tilt lever 34 is at the neutral position, and outputs an on signal when the tilt lever 34 is operated to the forward tilt position or the rear tilt position.

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 a CPU) 42 as target vehicle speed setting means, target engine speed setting means, judgment means and control means. The control device 41 includes a read-only memory (ROM) 43,
It has a readable and rewritable memory (RAM) 44, an input interface 45 and an output interface 46. When executing a control program such as a control program in a normal traveling mode in which the vehicle travels without carrying out the loading operation, a control program in a loading operation mode in which the vehicle travels while carrying out the loading operation (hereinafter referred to as HAT), and the like. And various data necessary for the operation are stored. The RAM 44 has a CP
The calculation result of U42 and the like are temporarily stored. CPU42 is R
It operates based on the control program stored in OM43.

The engine speed sensor 15, turbine sensor 17, vehicle speed sensor 19, brake switch 27a, shift switch 32, and tilt switch 36 are connected to the CPU 42 via an input interface 45. The pressure sensor 24, the accelerator sensor 28, the inching sensor 29, the brake sensor 30, and the lift lever sensor 35 are connected to an A / D converter (analog / digital converter) (not shown) and a CPU via an input interface 45.
42.

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

The ROM 43 stores a map showing the relationship between the operation amount of the lift lever 33 and the throttle opening corresponding to the target engine speed, and the relationship between the operation amount of the accelerator pedal 25 and the throttle opening corresponding to the target engine speed, respectively. Have been. In both maps, the throttle opening increases in proportion to the operation amount from the state where the operation amount is zero, and the throttle opening is fully opened at the maximum operation amount. The ROM 43 stores a throttle opening corresponding to a predetermined target engine speed corresponding to a case where the tilt lever 34 is operated to the forward tilt or the backward tilt position.

The ROM 43 stores a map indicating the relationship between the operation amount of the accelerator pedal 25 at the time of HAT and the target vehicle speed Vhat. The target vehicle speed Vhat is 0 when the operation amount of the accelerator pedal 25 (accelerator operation amount) is 0.
And is set so as to rise in accordance with the accelerator operation amount.

The ROM 43 stores data for setting a map indicating the detected pressure (brake pedal pressure) of the brake sensor 30 during normal running and HAT, that is, the relationship between the operating force of the brake pedal 27 and the clutch pressure on the braking side. Is stored. The clutch pressure on the braking side means the engagement pressure of the clutch that is not the forward side of the forward clutch 8 and the reverse clutch 9. That is, it indicates the engagement pressure of the reverse clutch 9 during forward running, and indicates the engagement pressure of the forward clutch 8 during reverse running.

The map during normal running indicated by M1 in FIG.
The relationship between the brake pedal pressure and the clutch pressure is set so that a clutch pressure required to obtain a braking force equivalent to the operating force (pedal force) when the service brake is provided is obtained. The map at the time of HAT indicated by M2 in FIG. 6 has an upper limit value for the clutch pressure,
Even at the same brake pedal pressure, the braking force is set so as to be smaller than during normal running.

The CPU 42 controls each of the sensors 15, 17, 1
9, 24, 28, 29, 30, 35, brake switch 27a, shift switch 32, and tilt switch 36
And operates according to various control programs stored in the ROM 43 to output control command signals to the throttle actuator 7 and the valves 10, 11, and 13.

The CPU 42 determines, based on detection signals from the accelerator sensor 28, the lift lever sensor 35, and the tilt switch 36, whether the vehicle is traveling normally or HAT. CPU4
2 is a throttle opening (THlift) corresponding to cargo handling, which is a target engine speed set based on the operation amounts of the lift lever 33 and the tilt lever 34, and the accelerator pedal 25.
H is greater than the throttle opening (THrun) corresponding to the accelerator, which is the target engine speed corresponding to the operation amount of
It is determined that the vehicle is AT, and otherwise, it is determined that the vehicle is traveling normally.

In the normal running mode, the CPU 42 controls the throttle actuator 7 so that the clutch on the traveling side is fully engaged and the throttle opening THrun corresponding to the accelerator is attained. Shift lever 3
1 means the clutch corresponding to the shift position. When the shift position is the forward position F, the clutch is the forward clutch 8, and when the shift position is the reverse position R, the clutch is the reverse clutch 9.

In the HAT mode, the CPU 42 controls the throttle actuator 7 so that a throttle opening corresponding to a target engine speed at which a hydraulic pressure required for cargo handling operation can be secured. The CPU 42 is provided with the shift switch 3
2, the clutch corresponding to the traveling direction in which the shift lever 31 is operated is brought into the half-clutch state, and the two clutch valves 10 are set so that the target vehicle speed Vhat corresponds to the operation amount of the accelerator pedal 25. , 1
1 is controlled to adjust the engagement pressure of the clutch on the traveling side. The engagement pressure of the clutch becomes the driving force, and the acceleration is determined by the difference between the driving force and the running resistance. When the driving force-running resistance is positive, the acceleration is performed, when it is zero, the speed is constant, and when it is negative, the deceleration is performed. The negative maximum is deceleration due to running resistance.

The CPU 42 adjusts the clutch engagement pressure by feedback control. In this embodiment, C
The PU 42 performs feedback control by proportional integration control (PI control). The clutch pressure increment ΔP is determined by the integral gain K
_I , the proportional gain K _P , the vehicle speed deviation (difference between the target vehicle speed and the detected vehicle speed) e, and the difference Δe are determined by the following equation.

ΔP = K _I · e + K _P · Δe However, when the shift lever 31 is in the neutral position,
U42 outputs a current command value for keeping both clutches 8 and 9 in a disengaged state to both clutch valves 10 and 11, and opens the throttle opening THlift corresponding to the cargo handling and the throttle opening THrun corresponding to the accelerator whichever is larger. The throttle actuator 7 is controlled so as to be in the range.

When the CPU 42 shifts from HAT to normal running, when the engine speed decreases and the difference between the input and output speeds of the clutch on the traveling side falls within a predetermined range,
The engagement pressure of the clutch in the half-clutch state is increased so that the clutch is completely engaged. At this time, the turbine sensor 17 is used to detect the number of revolutions on the input side of the clutch.

The CPU 42 operates the brake pedal 2 during HAT.
When 7 is operated, the clutch pressure on the braking side is controlled via the clutch valve so as to perform the braking by limiting the braking force to be smaller than the braking force during normal running.

Next, the operation of the device configured as described above will be described. The engine 1 is rotated at an engine speed corresponding to the throttle opening. The rotation of the engine 1 drives the hydraulic pump 20 to be in a state where hydraulic oil can be supplied to the lift cylinder 22 and the tilt cylinder. The rotation of the engine 1 is transmitted to the transmission 3 via the output shaft 1a and the torque converter 2.

When the shift lever 31 is operated to the neutral position, the clutches 8 and 9 are held in a disengaged state, and the rotation of the engine 1 is not transmitted to the output shaft 3b of the transmission 3. When the shift lever 31 is operated to the forward position, the hydraulic pressure of the pressure receiving chamber 8a of the forward clutch 8 is adjusted, the forward clutch 8 is engaged, and the rotation of the engine 1 is transmitted to the output shaft 3b via the forward clutch 8. The state is transmitted. When the shift lever 31 is operated to the reverse position, the hydraulic pressure in the pressure receiving chamber 9a of the reverse clutch 9 is adjusted, the reverse clutch 9 is engaged, and the rotation of the engine 1 is transmitted to the output shaft 3b via the reverse clutch 9. Is transmitted.

When the brake pedal 27 is operated during traveling, the clutch that is not on the forward side is engaged, and a braking force is obtained. When the brake pedal 27 is operated, the CPU 42 controls the corresponding clutch valve so that the clutch that is not on the forward side is also engaged. The engagement pressure of the clutch is controlled to be a value corresponding to the operation amount of the brake pedal 27. The parking brake 12 is also used as a brake for preventing reverse running during braking during HAT.

When the CPU 42 determines that the vehicle speed is lower than or equal to the stop vehicle speed during normal running and that the state in which the brake operation signal is input has continued for a predetermined time (for example, about 0.5 seconds), the CPU 42 sets the brake valve 13 Outputs a braking command signal. The stop vehicle speed means a low speed that is determined to be zero by the vehicle speed sensor 19, and is, for example, about several cm per second. When the braking command signal is output to the brake valve 13, the hydraulic pressure is not supplied to the pressure receiving chamber 12c, and the brake pad 12b is disposed at the braking position where the brake pad 12b is pressed against the disk 12a by the spring force, so that the parking brake 12 is in the braking state. Becomes Therefore, when the forklift is stopped, the parking brake 12 is automatically switched from the braking release state to the braking state. When the accelerator pedal 25 is depressed, the braking state is released.

When the inching pedal 26 is depressed and operated to the inching position, the HAT control is not performed, the clutch on the traveling side is held in a half-clutch state, and the forklift can be driven at a very low speed by manual operation.

Next, the shift control during HAT and the braking control during HAT will be described in more detail with reference to the flowcharts of FIGS. The CPU 42 repeats the processing of the flowcharts of FIGS. 2 to 5 at a predetermined cycle, for example, every 10 milliseconds.

In step S 1, the CPU 42 responds to the load opening throttle lift THlift corresponding to the target engine speed for the cargo handling operation and the operation amount of the accelerator pedal 25 based on the operation amounts of the lift lever 33 and the tilt lever 34 in step S 1. The throttle opening THrun corresponding to the accelerator corresponding to the set target engine speed is calculated. That is, CPU
Reference numeral 42 calculates the operation amount of the lift lever 33 from the output signal of the lift lever sensor 35, and obtains the corresponding throttle opening from the map. Then, the throttle opening is compared with the throttle opening corresponding to the position of the tilt lever 34, and the larger throttle opening is set as the throttle opening THlift for cargo handling. Further, an accelerator operation amount is calculated from an output signal of the accelerator sensor 28, and a throttle opening THrun corresponding to the accelerator is obtained from a map. CPU42
Constitutes a target engine speed setting means for the accelerator operation amount and a target engine speed setting means for the cargo operation amount in step S1.

Next, in step S2, the CPU 42 determines whether or not the shift lever 31 is in the neutral position. If the shift lever 31 is in the neutral position, the process proceeds to step S3. In step S3, the CPU 42 calculates the two throttle opening degrees THlift, TH calculated in step S1.
so that the throttle opening of the larger of the runs is
A command signal corresponding to the throttle actuator 7 is output.

If the shift lever 31 is not at the neutral position in step S2, the CPU 42 proceeds to step S4 to compare the two throttle opening degrees THlift and THrun. If the throttle opening THlift for cargo handling is greater than the throttle opening THrun for accelerator in step S4, C
The PU 42 determines that it is a HAT and proceeds to step S5, where HA
The flag fHAT indicating the T mode is set to 1.
Next, the CPU 42 proceeds to step S6, and outputs a command signal to the throttle actuator 7 so as to attain the throttle opening THlift. As a result, the engine speed becomes the speed at which the hydraulic pressure required for the cargo handling operation can be secured. CPU42
Constitutes a judgment means for judging whether the vehicle is traveling normally or HAT in step S4.

Next, the CPU 42 proceeds to step S7, and based on the output signal of the accelerator sensor 28, the accelerator pedal 2
The target vehicle speed Vhat corresponding to the operation amount of No. 5 is set. Next, in step S8, the CPU 42 detects the target vehicle speed Vhat and the detected vehicle speed (actual vehicle speed) Vse based on the output signal of the vehicle speed sensor 19.
Based on n, PI control of clutch pressure is performed. Since the HAT generally has a low vehicle speed, the engine speed at which the hydraulic pressure required for the cargo handling operation can be secured is higher than the engine speed corresponding to the operation amount of the accelerator pedal 25. Therefore, the vehicle is controlled to a desired vehicle speed by setting the traveling clutch to a half-clutch state and adjusting the engagement pressure. The CPU 42 constitutes a target vehicle speed setting means for the accelerator operation amount in step S7.

If the throttle opening THlift is not greater than the throttle opening THrun in step S4, the CPU 4
2 determines that the vehicle is traveling normally, proceeds to step S9, and sets the flag f
The HAT is set to 0, that is, a state indicating that the mode is not the HAT mode. Next, the CPU 42 proceeds to step S10, and controls the normal traveling mode. That is, a command value for supplying current to the corresponding clutch valve is output so as to completely engage the clutch on the traveling side, and a command signal is output to the throttle actuator 7 so that the throttle opening THrun corresponding to the accelerator is obtained.

Next, the target vehicle speed Vhat in step S7
Will be described in detail with reference to FIG. CPU4
2 calculates a target vehicle speed Vhat from the detection signal of the accelerator sensor 28 using a map in step S701. Then C
PU42 determines in step S702 that the target vehicle speed Vhat is HAT.
It is determined whether or not the speed is higher than the upper limit speed VU. If the speed is higher, the process proceeds to step S703, and the target vehicle speed Vhat is set to the upper limit speed VU. If the target vehicle speed Vhat is equal to or lower than the upper limit speed VU, the CPU 42 proceeds to step S704, and sets the target vehicle speed Vhat to the vehicle speed VM calculated from the map.

Next, in step S705, the CPU 42 determines whether or not the brake pedal 27 is operated (brake ON). If the brake pedal 27 has been operated, the process proceeds to step S706, where the target vehicle speed Vhat is set to 0.
Is set, and the target vehicle speed setting process is ended. If the brake pedal 27 is not operated, the target vehicle speed setting process is ended as it is.

Therefore, in the target vehicle speed setting process in step S7, the target vehicle speed Vhat corresponding to the accelerator operation amount is set to HA.
If the speed is higher than the upper limit speed VU at the time T, the speed is set to the upper limit speed VU. If the brake is ON, the target vehicle speed Vhat is 0 regardless of the target vehicle speed Vhat corresponding to the accelerator operation amount.
Is set to

Next, the braking action when the brake pedal 27 is operated during forward running during the HAT will be described with reference to FIGS.
This will be described according to the flowchart of FIG. CPU 42 is shown in FIG.
The process of the flowchart shown in FIG. 5 is performed by an interrupt process in the middle of the HAT control process for each control cycle. When power is supplied to the control device 41, C
PU42 is a map M showing the relationship between the brake pressure and the simultaneous engagement brake pressure of the forward clutch 8 and the reverse clutch 9.
1 and M2 are set based on the data stored in the ROM 43 and stored in the RAM 44.

At step S501, the CPU 42 sets the flag f
It is determined whether HAT is 1 and the brake is ON. The flag fHAT is 1, that is, the HAT mode and the brake is ON.
If so, the CPU 42 proceeds to step S502 and sets the minimum simultaneous engagement pressure PhatFR of the forward clutch 8 and the reverse clutch 9 when the brake pedal 27 is ON. The minimum simultaneous engagement pressure PhatFR is a state in which, when the operation amount of the brake pedal 27 is small, the pressure is not applied to the clutch on the braking side due to the variation of the detection signal of the brake sensor 30 irrespective of the operation of the brake pedal 27. It is provided to avoid becoming. Minimum simultaneous engagement pressure PhatF
R is set lower than the engagement pressure at the time of simultaneous engagement brake during normal running.

Next, the CPU 42 proceeds to step S503, and calculates a simultaneous engagement brake pressure Pbrk corresponding to the operation force (brake pressure) of the brake pedal 27 from the map M2. Next, the CPU 42 proceeds to step S504, and determines whether or not the simultaneous engagement brake pressure Pbrk is lower than the minimum simultaneous engagement pressure PhatFR.

If the simultaneous engagement brake pressure Pbrk is smaller than the minimum simultaneous engagement pressure PhatFR, the CPU 42 proceeds to step 50.
5 and the reverse clutch 9 sets the minimum simultaneous engagement pressure PhatF as the command current value RIcon for the reverse clutch valve 11.
The command current value IPhatFR that outputs R is output. If the simultaneous engagement brake pressure Pbrk is not smaller than the minimum simultaneous engagement pressure PhatFR, the CPU 42 proceeds to step 506 so that the reverse clutch 9 becomes the simultaneous engagement brake pressure Pbrk as the command current value RIcon for the reverse clutch valve 11. Output the desired command current value IPbrk.

Next, the CPU 42 proceeds to step S507, and determines whether or not the detected vehicle speed Vsen has changed from a predetermined low speed VL to less than a predetermined low speed VL or the flag fbrk HAT is 1.
The predetermined low speed VL is, for example, approximately 0.25 km / h, which is almost a speed close to stopping. The detected vehicle speed Vsen is a predetermined low speed VL
It is determined that the detected vehicle speed Vsen [3] three cycles earlier is equal to or higher than the predetermined low speed VL, the detected vehicle speed Vsen [2] two cycles ago is equal to or higher than the predetermined low speed VL, and one cycle earlier. It is assumed that the condition that the detected vehicle speed Vsen [1] is lower than the predetermined low speed VL and the present cycle, that is, the condition that the current detected vehicle speed Vsen [0] is lower than the predetermined low speed VL, is satisfied. If the determination condition of step S507 is satisfied, the CPU 42 proceeds to step S508, and sets the command current value Ioff for disengaging both clutches 8, 9 to the command current value FIco of the forward clutch valve 10 to prevent reverse running.
n and the command current value RIcon of the reverse clutch valve 11 are output. By this processing, the pressure of the clutches 8, 9 is released, and both clutches 8, 9 are disengaged.

Next, the CPU 42 proceeds to step S509, sets the flag fbrk HAT to 1, and then proceeds to step S51.
At 0, the flag fbrkfree is set to 1. After that, the CPU 42
Executes a control routine of the parking brake 12.

If the determination condition in step S507 is not satisfied, the CPU proceeds to step S511, and sets the flag fbr
Set kfree to 0. Thereafter, the CPU 42 executes a control routine of the parking brake 12 shown in FIG.

The CPU 42 sets the flag f in step S501.
If HAT is 1 and the brake is not ON, step S
Proceeding to 512, it is determined whether the brake is off. If the brake is off in step S512, the CPU
42 proceeds to step S513, sets the flag fbrk HAT to 0, and then proceeds to the control routine of the parking brake 12.
If the brake is not OFF in step S512, the CPU
42 advances to the control routine of the parking brake 12.

In the control routine of the parking brake 12, in step S520, the CPU 42 determines whether or not the flag fbrkfree is 1 and the brake is ON. If the flag fbrkfree is 1 and the brake is ON, the CPU 42 proceeds to step S5.
21 and the flag fbr for driving the brake valve 13
After setting k to 1, the process proceeds to step S522, in which a control signal for bringing the parking brake 12 into the braking state (parking brake ON) is output to the brake valve 13, and the process ends.
If the flag fbrkfree is 1 and the brake is not ON in step S520, the CPU 42 proceeds to step S523, in which the shift lever 31 is moved forward or backward, and the brake OF is released.
It is determined whether F and the flag fHAT are 1 or not. If the determination condition is satisfied, the CPU 42 proceeds to step S524, sets the flag fbrk for driving the brake valve 13 to 0, and then proceeds to step S525 to output a control signal for setting the parking brake 12 to the brake release state (parking brake OFF). After the output to the brake valve 13, the process ends. If the determination condition is not satisfied in step S523, the CPU 42
Ends the processing as it is.

When the brake pedal 27 is operated during the reverse movement during the HAT, the same operation is performed by exchanging the forward movement and the reverse movement in the above-described processing. This embodiment has the following effects.

(1) When the brake pedal 27 is operated during HAT, the CPU 42 performs braking so that the braking force is equal to or less than a predetermined upper limit. Therefore, it is possible to prevent a large sudden braking force from acting at the time of a HAT having a small center of gravity and a low stability, thereby improving the stability of the vehicle during the HAT.

(2) Since the braking force is obtained by simultaneous engagement of the forward clutch 8 and the reverse clutch 9, there is no need to provide a service brake for braking, and the number of assembly steps is reduced accordingly.

(3) When a braking force is obtained by simultaneous engagement of the forward clutch 8 and the reverse clutch 9 during HAT, the value of the clutch pressure on the braking side corresponding to the brake operating force corresponds to the brake operating force during normal running. Therefore, the stability of the vehicle during HAT can be further improved.

(4) Since the maximum speed VU during HAT is regulated to be lower than the maximum vehicle speed during normal running, the stability of the vehicle when a braking force is applied during HAT with a high center of gravity and low stability is achieved. Is improved.

(5) When the braking force is applied by operating the brake pedal 27 during HAT, the target vehicle speed Vhat is set to 0 regardless of the operation amount of the accelerator pedal 25. When a braking force is applied while keeping the target vehicle speed Vhat at a value corresponding to the accelerator operation amount, the target vehicle speed Vha is opposed to the braking force.
In order to follow t, the clutch pressure on the traveling side increases, making it difficult to obtain a desired braking force and reducing the durability of the clutch. However, when the target vehicle speed Vhat is set to 0, the clutch pressure on the traveling side is reduced, a desired braking force is obtained, and energy loss is reduced.

(6) When setting the clutch pressure on the braking side during brake braking during HAT, the simultaneous engagement brake pressure Pbrk corresponding to the brake pressure is compared with the minimum simultaneous engagement pressure PhatFR, and the simultaneous engagement brake pressure is determined. When the pressure Pbrk is small, the clutch pressure on the braking side is set to the minimum simultaneous engagement pressure PhatFR. Therefore, the operation amount of the brake pedal 27 is small,
Even if the detection signal of the brake sensor 30 varies, the clutch pressure is adjusted to at least the minimum simultaneous engagement pressure PhatFR during braking, so that the braking is stably performed.

(7) When obtaining a braking force by simultaneous engagement of the forward clutch 8 and the reverse clutch 9 during HAT, if the vehicle speed decreases to a vehicle speed close to stop, the clutch pressure of both clutches 8 and 9 becomes non-engaged. It is held at the clutch pressure. Therefore, it is possible to prevent the vehicle from running in the reverse direction due to an increase in the clutch pressure on the braking side when the vehicle speed is reduced.

(8) Even if the forward clutch 8 and the reverse clutch 9 are disengaged during HAT, the brake pedal 2
If the parking brake 7 is operated, the parking brake 12 is in the braking state, so that the parking brake 12 can be reliably stopped even on a slope.

(9) The turbine sensor 17 and the vehicle speed sensor 19 detect the number of rotations on the input side or output side of the clutch, respectively, by using the gears 16 and 18 constituting the gear train incorporated in the transmission 3 as detected parts. I do. Therefore, it is not necessary to newly provide a detected part for detecting the rotation speed on the input side or the output side.

(10) Since a wet hydraulic clutch is used as the forward clutch 8 and the reverse clutch 9,
The durability is unlikely to decrease even if the half-clutch state is frequently used.

(Second Embodiment) Next, a second embodiment will be described with reference to FIGS. In this embodiment, when a braking force is obtained by simultaneous engagement of the forward clutch 8 and the reverse clutch 9 during HAT, the upper limit of the clutch pressure on the braking side is changed according to the lift and weight of the load. This is different from the above embodiment. The mechanical configuration is basically the same as that of the above-described embodiment, and is different in that a lift detecting means is provided. Also, the map for setting the upper limit of the clutch pressure on the braking side is different. Further, the flowchart for controlling the braking force when the brake pedal 27 is operated during the HAT is slightly different from the first embodiment.

As the lift detecting means, a lift switch for detecting whether or not the fork 21 is at a predetermined height (predetermined lift) or a lift sensor capable of continuously detecting the height of the fork 21 is used. Provided. As shown in FIG. 10A, the elevation switch 37 is attached to the outer mast constituting the mast 23 at a predetermined height position. Lift switch 37
Consists of a proximity switch, detects an object to be detected (not shown) fixed to the inner mast side of the mast 23, and outputs an ON signal when the fork 21 exceeds a predetermined lift Hs. An off signal is output when the value is less than the predetermined value. The predetermined lift differs depending on the model, but is set to, for example, a height approximately half of the maximum lift Hmax. The elevation switch 37 is connected to the CPU 42 via the input interface 45.

As the lift sensor 38, for example, a conventional reel-type lift sensor is used, and is provided below the lift cylinder 22 as shown in FIG.
The lift sensor 38 includes a reel around which a wire connected to the fork 21 or lift bracket at one end is wound, and a rotation detector (neither is shown) for detecting a rotation amount of the reel. Lift sensor 38 is not shown in A
CPU via I / D converter and input interface 45
42.

The ROM 43 stores a common map indicating the relationship between the brake pedal pressure and the clutch pressure on the braking side during normal running and HAT, and the upper limit of the clutch pressure on the braking side in accordance with the lift and the weight of the load. Data for setting a map to be calculated is stored. When power is supplied to the control device 41, the CPU 42 sets the maps shown in FIGS. 8 and 9A and 9B based on the data stored in the ROM 43 and stores the maps in the RAM 44. As shown in FIG. 8, a map M indicating the relationship between the brake pressure and the simultaneous engagement brake pressure of the forward clutch 8 and the reverse clutch 9
In No. 3, the relationship between the brake pedal pressure and the clutch pressure on the braking side is set to be the same as that of the map M1 of the first embodiment.

The map for setting the upper limit of the clutch pressure on the braking side in accordance with the lift and the weight of the load includes a case where the lift switch 37 is provided as the lift detecting means and a case where the lift sensor 38 is provided.
Is different from when equipped with When the lift switch 37 is provided as the lift detecting means, the map M shown in FIG.
4 is stored in the storage RAM 44, and when the elevation sensor 38 is provided, the map M5 shown in FIG.
4 is stored.

In the map M4, the upper limit of the clutch pressure changes between the predetermined height Hs and the predetermined height Hs. When the load is lower than the predetermined lift Hs, the upper limit of the clutch pressure becomes larger as the load becomes heavier. When the load is higher than the predetermined lift Hs, the upper limit of the clutch pressure becomes smaller as the load becomes heavier.

The map M5 is set so that the upper limit of the clutch pressure gradually decreases as the lift increases. When the load is lower than a certain height H0, the upper limit of the clutch pressure becomes larger as the load becomes heavier. When the load is higher than a certain height H0, the upper limit of the clutch pressure becomes smaller as the load becomes heavier. FIG.
(A) and (b) each show only three lines for three types of weights, but when the weight of the load is the weight between the lines, C
The PU 42 calculates the upper limit of the clutch pressure by an interpolation method.

The flowchart for controlling the braking force when the brake pedal 27 is operated during the HAT is shown in FIG.
Is slightly different from the embodiment of FIG. That is, as shown in FIG. 7, steps S 503 a and S 503 b for performing another process are provided between steps 503 and 504 in the flowchart of FIG. 4 of the first embodiment. I have.

Therefore, in this embodiment, when the brake pedal 27 is operated during forward running during HAT, the CPU
42 sets the minimum simultaneous engagement pressure PhatFR of the forward clutch 8 and the reverse clutch 9 when the brake pedal 27 is ON in step S502. Next, the CPU 42 proceeds to step S503, and obtains the simultaneous engagement brake pressure Pbrk corresponding to the operation force (brake pressure) of the brake pedal 27 from the map M3. Next, the CPU 42 proceeds to step S503a.
The upper limit value Pbrkmax of the simultaneous engagement clutch pressure according to the weight and the lift of the load is obtained from the map M4 or M5. Next, the CPU 42 proceeds to step S503b, and substitutes a clutch pressure equal to or lower than the upper limit Pbrkmax of the simultaneous engagement clutch pressure into the simultaneous engagement brake pressure Pbrk. That is, step S503
If the simultaneous engagement brake pressure Pbrk obtained in the step is less than the upper limit value Pbrkmax, the simultaneous engagement brake pressure Pbrk is maintained as it is. If the simultaneous engagement brake pressure Pbrk is equal to or more than the upper limit value Pbrkmax, the simultaneous engagement brake pressure Pbrk is used. To the upper limit value Pbrkmax.

Next, the CPU 42 proceeds to step S504, and executes the following steps S504 to 513 and each processing of the flowchart of FIG. Therefore, in this embodiment, (1), (2) and (4) to
The following effect is obtained in addition to the effect of (10).

(11) The CPU 42 controls the forward clutch valve 10 and the reverse clutch valve 1 so as to apply a braking pressure equal to or lower than a preset upper limit corresponding to the lift and weight of the load.
Control 1 Therefore, the HAT corresponding to the change in the center of gravity of the vehicle can be used without performing complicated processing for calculating the center of gravity of the vehicle.
The stability of the middle vehicle can be improved.

(12) A map M3 showing the relationship between the brake pedal pressure and the clutch pressure on the braking side is obtained during normal running and at H
Since it is common at the time of AT, the work of setting the map is simplified. (13) When calculating the upper limit of the clutch pressure on the braking side from the lift and the weight of the load, the A / D is different when the lift switch 37 is used as the lift detecting means than when the lift sensor 38 is used. The operation of the CPU 42 is simplified because no converter is required.

(Third Embodiment) Next, a third embodiment will be described with reference to FIGS. This embodiment differs from the first embodiment in that the upper limit of the target vehicle speed Vhat during HAT is changed according to the lift of the load. The mechanical configuration is basically the same as that of the first embodiment, and is different in that a lift detecting means is provided.

The target vehicle speed Vhat during HAT is stored in the ROM 43.
For setting a map indicating the relationship between the upper limit of the load and the lift of the load. The CPU 42 is a control device 41
When the power is supplied to the RAM, a map is set based on the data stored in the ROM 43 and stored in the RAM 44. The map showing the relationship between the upper limit of the target vehicle speed Vhat and the lift of the load differs between a case where the lift switch 37 is provided as the lift detecting means and a case where the lift sensor 38 is provided. When the elevation switch 37 is provided as the elevation detection means, the map M6 shown in FIG. 12A is stored in the storage RAM 44, and when the elevation sensor 38 is provided, the map M6 shown in FIG.
The map M7 shown in (b) is stored in the storage RAM 44.

In the map M6, the upper limit of the target vehicle speed Vhat changes between the predetermined height Hs and the predetermined height Hs. When the height is less than the predetermined height Hs, the upper limit is larger than when the height is equal to or more than the predetermined height Hs. The map M7 is set so that the upper limit of the target vehicle speed Vhat gradually decreases as the lift increases.

The flowchart for setting the target vehicle speed Vhat at the time of HAT is slightly different from the flowchart of the first embodiment. As shown in FIG.
In the flowchart for setting the target vehicle speed Vhat at the time of AT, an upper limit speed VUH according to the lift is used instead of the upper limit speed VU in steps S702 and S703 in the flowchart shown in FIG.

When setting the target vehicle speed Vhat during HAT, the CPU 42 calculates the target vehicle speed Vha calculated in step S701.
It is determined whether or not t is greater than the upper limit speed VUH in step S70.
Judge with 2. If the target vehicle speed Vhat is higher than the upper limit speed VUH, the CPU 42 sets the target vehicle speed Vhat to the upper limit speed VUH in step S703, and sets the target vehicle speed Vhat.
Is equal to or lower than the upper limit speed VUH, the target vehicle speed Vhat is set to the vehicle speed VM calculated from the map in step S704.

This embodiment has the following effects in addition to the effects (1) to (10) of the first embodiment. (14) The target vehicle speed Vhat at the time of HAT has an upper limit set in accordance with the lift. Therefore, the stability of the vehicle at the time of HAT where the center of gravity of the vehicle is high is further improved.

(15) Target vehicle speed Vhat corresponding to lift
When calculating the upper limit of the lift, the lift switch 3
When the CPU 42 is used, an A / D converter is not required and the CPU 42
Is simplified.

(16) Target vehicle speed Vhat corresponding to lift
When calculating the upper limit of the height, the lift sensor 38 is used as the lift detecting means.
In the case where is used, a more appropriate upper limit speed can be set. (Fourth Embodiment) Next, a fourth embodiment will be described with reference to FIGS. In this embodiment, the HAT
The difference from the first embodiment is that the upper limit of the middle engine speed is changed according to the vehicle speed and the weight of the load. The mechanical configuration is the same as in the first embodiment.

The ROM 43 stores the detected vehicle speed Vsen during HAT.
For setting a map indicating the relationship between the engine speed and the engine speed. The CPU 42 is a control device 41
When the power is supplied to the RAM, a map is set based on the data stored in the ROM 43 and stored in the RAM 44. A map M8 indicating the relationship between the detected vehicle speed Vsen and the engine speed is, as shown in FIG.
Is set so that the engine speed is constant from 0 to a predetermined low speed, and from the predetermined low speed to the maximum speed during HAT, the upper limit of the engine speed gradually decreases as the vehicle speed increases. When the vehicle speed is the same, the upper limit of the engine speed increases as the weight of the load increases. Although only two lines, heavy and light, are shown in the map, if the weight of the load is the weight between the lines, the CPU 42 calculates the upper limit of the engine speed by interpolation.

When the shift lever 31 is not in the neutral position during the processing of the flowchart shown in FIG. 2 in the first embodiment, the CPU 42 executes the processing of the flowchart of FIG. According to the flowchart shown in FIG. 13, the CPU 42 limits the engine speed during the HAT so as to be equal to or less than the upper limit corresponding to the load. This restriction is applied when the weight of the load is equal to or more than a predetermined value, and is not limited when there is no load or when the weight of the load is less than the predetermined value.

Next, according to the flowchart of FIG.
Control of the engine speed during T will be described. CPU
42 is a step S401, in which both throttle openings THlift,
Compare the magnitude of THrun and calculate the throttle opening T for cargo handling.
If Hlift is larger than the throttle opening THrun corresponding to the accelerator, the CPU 42 determines that the HAT is the HAT, and proceeds to step S4.
02, a flag fH indicating that the HAT mode is set.
Set AT to 1. Next, the CPU 42 proceeds to step S403, and determines whether the weight of the load is equal to or more than a predetermined value. If the weight of the load is equal to or more than the predetermined value in step S403, the CPU 42
Proceeds to step S404, and calculates the upper limit of the engine speed corresponding to the weight of the load and the vehicle speed from the map M8.

Next, the CPU 42 proceeds to step S405, and determines whether or not the throttle opening THlift corresponding to cargo handling is larger than the throttle opening THU corresponding to the upper limit of the engine speed. If the throttle opening THlift for cargo handling is large, the process proceeds to step S406, and a command signal is output to the throttle actuator 7 so that the throttle opening THU is obtained. If the throttle opening THlift for cargo handling is not large, the process proceeds to step S407, and a command signal is output to the throttle actuator 7 so that the throttle opening THlift is obtained. If the weight of the load is less than the predetermined value in step S403, the CPU 42 proceeds to step S407.
To output a command signal to the throttle actuator 7 so that the throttle opening becomes THlift.

If the throttle opening THlift corresponding to cargo handling is not greater than the throttle opening THrun corresponding to the accelerator in step S401, the CPU 42 determines that the vehicle is traveling normally, and proceeds to step S408 to set the flag fHAT.
To 0, that is, a state indicating that the mode is not the HAT mode.
Next, the CPU 42 proceeds to step S409, and controls the normal traveling mode.

Therefore, this embodiment has the following effects in addition to the effects (1) to (10) of the first embodiment. (17) When the weight of the load is equal to or more than the predetermined value, the control unit controls the engine speed at the time of HAT to be equal to or lower than an upper limit set in advance according to the vehicle speed and the weight of the load.
Therefore, the load does not rise at a high speed in a state where the vehicle speed is high with a load having a certain weight or more, and the stability of the vehicle is improved.

(18) Since the upper limit of the engine speed is set according to the vehicle speed and the weight of the load, the upper limit of the engine speed is set according to the vehicle speed only by determining whether the weight of the load is equal to or more than a predetermined value. In comparison, the upper limit of the engine speed can be set to a more appropriate value.

(Fifth Embodiment) Next, a fifth embodiment will be described with reference to FIG. In this embodiment, HA
Even if the throttle opening THlift for cargo handling becomes smaller than the throttle opening THrun for accelerator during T, the CPU 4
2 differs from the first embodiment in that the clutch on the traveling side is not shifted to the fully engaged state in the normal traveling mode until the lifting of the load stops. Other configurations are basically the same.

The ROM 43 stores a map showing the relationship between the position of the lift lever 33 and the target engine speed. As shown in FIG. 15, the map M9 includes the lift lever 3
3 is set such that the target engine speed increases as the opening increases from a position where the opening of the control valve (not shown) closes the port for opening the opening of the control valve to a position where the port is opened by a predetermined amount. ing.

During HAT, the engine speed becomes higher than the engine speed corresponding to the accelerator operation amount, and in this state, the traveling side clutch is held in a half clutch state so that the vehicle speed becomes the target vehicle speed corresponding to the accelerator operation amount. Then, the vehicle speed is controlled by feedback controlling the engagement pressure of the clutch. If the driver slightly lifts the lift lever 33 or increases the accelerator operation amount while the load is rising, the target engine speed for cargo handling may become lower than the target engine speed for accelerator.

In each of the above-described embodiments, when the target engine speed for cargo handling becomes equal to or lower than the target engine speed for accelerator operation, it is determined that the vehicle is in the normal running mode, and the clutch on the traveling side is shifted from the half-clutched state to the fully engaged state. Is moved to Therefore, the clutch on the traveling side may shift from the half-clutch state to the fully engaged state even while the load is rising. While the load is rising, it is not preferable that a shock occurs because the stability of the vehicle is low.

In this embodiment, the CPU 42 controls the engine speed so that it becomes the maximum target engine speed determined by the throttle opening THlift corresponding to cargo handling and the throttle opening THrun corresponding to the accelerator. However, even if the throttle opening THlift for cargo handling becomes smaller than the throttle opening THrun for accelerator while the load is rising, the CPU 4
No. 2 does not shift the traveling clutch to the fully engaged state until the load stops. Therefore, it is possible to prevent the occurrence of a shock caused by the clutch changing from the half-clutch state to the fully engaged state while the load is rising.

The CPU 42 determines, based on the detection signal of the lift lever sensor 35, that the lifting of the load has stopped when the operation amount of the lift lever 33 becomes 0 from the rising side.
Therefore, in this embodiment, (1) of the first embodiment
The following effects are obtained in addition to the effects of (10).

(19) The CPU 42 keeps the clutch on the traveling side in a half-clutch state without fully engaging even if it is determined that the vehicle is traveling normally during the rising of the load during the HAT, and after the lifting of the load is stopped. Then, the control is performed such that the traveling side clutch is completely engaged and the normal traveling is performed. Therefore, it is possible to reliably prevent the occurrence of a shock due to the clutch changing from the half-clutched state to the fully engaged state while the load is rising.

(20) The CPU 42 sets the target engine speed to the larger of the target engine speed corresponding to the accelerator operation amount and the target engine speed set based on the operation amount of the cargo handling operation means, and sets the target engine speed. Control is performed so that the number of rotations becomes equal. Therefore, after the lifting of the load is stopped, the engine speed at the target vehicle speed can be reached in a short time when the traveling side clutch is brought into the fully engaged state and the normal traveling is started.

(21) When the lift lever 33 is operated upward, the control of the engine 1 is performed such that the engine speed increases after the control valve is opened by a predetermined amount. Even if the engine speed is immediately increased in conjunction with the opening of the control valve, the pressurized oil is not immediately supplied to the lift cylinder 22, so that the state becomes empty. However, by increasing the engine speed after the control valve is slightly opened, the puffiness is avoided and the fuel efficiency is improved.

(Sixth Embodiment) Next, a sixth embodiment will be described with reference to FIGS. In this embodiment, the driving wheel 5a is provided with a service brake (service brake) 6, and a braking force corresponding to the operating force of the brake pedal 27 is applied to the driving wheel 5a by hydraulic pressure. It is significantly different from the mechanical configuration of each embodiment. The brake pedal 27 is provided with a brake switch 27a for detecting that the brake pedal 27 has been operated to the braking position. The other mechanical configuration except for the brake pedal 27 is the same as that of the first embodiment. In addition, instead of detecting the input-side rotational speed of the clutch with the turbine sensor 17, the rotational speed is estimated and obtained from the engine rotational speed and the weight of the load.
7 is not required in the above embodiment.

The turbine speed NT and the engine speed NE
Is referred to as the speed ratio of the torque converter 2, which becomes smaller as the running load becomes larger, and becomes larger as the running load becomes smaller. The speed ratio of the torque converter 2 when the HAT ends is not always constant, but the weight of the load can be detected. Therefore, the CPU 42 estimates the turbine speed NT from the engine speed NE using the most possible speed ratio from the weight of the load.

The control during HAT is performed in the same manner as in the first embodiment, except for the control when the brake pedal 27 is operated. That is, the CPU 42 controls the vehicle speed at the time of the HAT according to the flowcharts of FIGS. 2 and 3 in the same manner as in the first embodiment. Therefore, during HAT, the brake pedal 27
Is operated, the target vehicle speed Vhat becomes 0 irrespective of the accelerator operation amount by the processing of steps S705 and S706 in the flowchart of FIG. As a result, the clutch valve is controlled such that the traveling side clutch pressure becomes zero.

During HAT, the target vehicle speed is set according to the accelerator operation amount, and if the difference between the detected vehicle speed Vsen and the target vehicle speed is large, control is performed so as to increase the clutch pressure on the traveling side. Therefore, if the target vehicle speed Vhat is a value corresponding to the accelerator operation amount even when the brake pedal 27 is depressed, the clutch pressure is increased by depressing the brake pedal 27 and recovering the amount reduced from the target vehicle speed. Is controlled. As a result, the brake pressure required for deceleration increases, the load on the foot increases, and wasteful energy is consumed. Further, if the operation of the brake pedal 27 is stopped in a state where the clutch pressure is high, the vehicle may accelerate rapidly. However, in this embodiment, the HAT
When the brake pedal 27 is operated during the operation, the target vehicle speed Vha
Since t is set to 0, the clutch pressure does not increase.

The braking force when the brake pedal 27 is operated is obtained by the braking force of the service brake 6 corresponding to the operation amount of the brake pedal 27. Therefore, unlike the first embodiment, control according to the flowcharts shown in FIGS. 4 and 5 is not performed.

Therefore, this embodiment has the following effects in addition to the effects (4), (5), (9) and (10) of the first embodiment. (22) When the brake pedal 27 is operated during the HAT, the target vehicle speed Vhat is set to 0, and the traveling side clutch pressure does not increase. Therefore, there is no need to continue the operation of the brake pedal 27 with a large depressing force for braking, and the brake operation becomes easier. Further, there is no possibility that the vehicle is suddenly accelerated when the operation of the brake pedal 27 is stopped.

(Seventh Embodiment) Next, a seventh embodiment will be described with reference to FIG. This embodiment is significantly different from the above embodiments in that the mode does not shift to the HAT mode if the vehicle speed is equal to or higher than a predetermined vehicle speed. The mechanical configuration is basically the same as that of the first embodiment. Also, HA
The flowchart for determining whether to perform the vehicle speed control in the T mode or the vehicle speed control in the normal traveling mode is slightly different from the first embodiment. As shown in FIG. 17, in the present embodiment, in the flowchart of FIG. 2 in the first embodiment, between steps S2 and S4,
The difference from the first embodiment is that a step S201 for determining whether the detected vehicle speed Vsen is lower than the predetermined vehicle speed Vd is provided. Other configurations are the same as those of the first embodiment.

The maximum speed (upper limit speed) VU during HAT is used as the predetermined vehicle speed Vd. Therefore, in this embodiment, in a state where the shift lever 31 is not in the neutral position, that is, in the traveling mode, first, the detected vehicle speed Vsen is equal to the predetermined vehicle speed V.
It is determined whether d (= VU) or less, that is, whether the detected vehicle speed Vsen is not higher than the predetermined vehicle speed Vd. And
If the detected vehicle speed Vsen is not equal to or higher than the predetermined vehicle speed Vd, the process proceeds to step S4, and it is determined whether or not the HAT mode is set. The processing after step S4 is the same as in the first embodiment.
If the detected vehicle speed Vsen is equal to or higher than the predetermined vehicle speed Vd in step S201, the CPU 2 proceeds to step S9, in which the flag fH
After setting the AT to 0, the control of the normal traveling mode is performed.

This embodiment has the following effects in addition to the effects (1) to (10) of the first embodiment. (23) If the vehicle speed is equal to or higher than the predetermined vehicle speed Vd, the operation does not shift to the HAT. If the transition from the normal traveling mode to the HAT mode is determined only by the magnitude of the throttle opening THlift corresponding to cargo handling and the throttle opening THrun corresponding to the accelerator, the transition to HAT may occur even when the vehicle is running at high speed. However, the transition to HAT in a high-speed state is disadvantageous in terms of vehicle stability. In this embodiment, the vehicle does not shift to the HAT at a speed higher than the predetermined speed, so that the stability of the vehicle during the HAT is improved.

(24) Since the upper limit speed VU during HAT is used as the predetermined vehicle speed Vd, there is no possibility of exceeding the upper limit speed during HAT, and the stability of the vehicle during HAT is further improved. The embodiment is not limited to the above,
For example, it may be embodied as follows.

In the third embodiment, the upper limit of the vehicle speed during HAT may be set according to the lift and the weight of the load. The map for setting the upper limit of the vehicle speed in accordance with the height and the weight of the load includes a height switch 3 as a height detection means.
7 and the height sensor 38 are different maps. When the lift switch 37 is used, the line in which the upper limit vehicle speed changes in two steps across the predetermined lift Hs is the upper limit vehicle speed corresponding to the weight of the load, similarly to the map M6 in FIG. It is provided at a position where At the same height, the higher the weight, the lower the upper limit vehicle speed. When the lift sensor 38 is used, as in the map M7 of FIG. 12B, a line where the upper limit vehicle speed gradually decreases with an increase in the lift is located at a position where the upper limit vehicle speed corresponds to the weight of the load. Provided. At the same height, the higher the weight, the lower the upper limit vehicle speed. In this case, the stability of the vehicle during cargo handling when the center of gravity of the vehicle is high is further improved.

In the second embodiment, when the upper limit of the clutch pressure on the braking side is set according to the lift and the weight of the load, the relationship between the lift of the load, the weight of the load and the upper limit of the clutch pressure is determined. The upper limit of the clutch pressure may be determined from a three-dimensional map by setting the three-dimensional map.

In the fourth embodiment, when setting the upper limit of the engine speed in accordance with the vehicle speed and the weight of the load,
The relationship between the vehicle speed, the weight of the load, and the upper limit of the engine speed may be set in a three-dimensional map, and the upper limit of the engine speed may be obtained from the three-dimensional map.

In the fifth embodiment, a lift sensor 38 may be provided to determine whether or not the load has stopped based on a detection signal from the lift sensor 38. In this case, although the fork 21 is stopped at the highest position, the lift lever 3
Even if 3 is not returned, it is possible to confirm that the load has stopped and shift to normal traveling.

A hydraulic braking clutch is incorporated in the transmission 3, and instead of applying the braking force when the brake pedal 27 is operated by the simultaneous engagement of the forward clutch 8 and the reverse clutch 9, the braking pressure of the braking clutch is received. A control valve for adjusting the engagement state by increasing or decreasing the hydraulic pressure in the room may be controlled by the CPU 42 to control the braking force. In this case, the braking force can be adjusted without considering the balance between the engaging forces of the forward clutch 8 and the reverse clutch 9, and the control becomes simpler than in the case of simultaneous engagement of the forward clutch 8 and the reverse clutch 9.

The parking brake 12 may have the function of the braking clutch. For example, a pressure control proportional solenoid valve is used as the brake valve 13 similarly to the clutch valves 10 and 11, and the brake valve 13 is controlled so that a braking force corresponding to the operation amount of the brake pedal 27 is obtained. .

In the first and second embodiments,
When the brake pedal 27 is operated during HAT, the minimum simultaneous engagement pressure PhatFR during braking is not set, and the map M3 is set.
The clutch pressure on the braking side may be controlled so as to become the simultaneous engagement brake pressure Pbrk obtained from the above. In this case, the processing is simplified.

When the brake is operated during the HAT to decelerate and becomes lower than the predetermined low speed VL, the parking brake 12 is not immediately put into the braking state. The parking brake 12 may be brought into the braking state after a lapse of about (seconds). In this case, when it is determined that the vehicle speed is lower than the low speed, the parking brake 1
2 does not work.

The third, fourth, and fifth embodiments may be combined with the second embodiment. Moreover, you may implement combining 1st-7th embodiment suitably. The pressure control proportional solenoid valve may be a proportional solenoid valve that is fully closed when the amount of power to the solenoid is 0 and whose opening increases in proportion to the amount of power. In this case, the clutch is kept in the disengaged state when no exciting current is supplied to the clutch valve. Then, only when the exciting current is supplied to the clutch valve corresponding to the traveling-side clutch, only the traveling-side clutch is engaged, and the driving force is transmitted to the output shaft.

The parking brake 1 built in the transmission 3
2 may be omitted and a normal parking brake may be provided. ○ Pressure receiving chamber 8 for both clutches 8 and 9 and parking brake 12
Instead of incorporating a hydraulic pump for supplying hydraulic pressure to the transmission cylinders a, 9a, and 12c in the transmission 3, a hydraulic pump 20 for supplying hydraulic oil to the lift cylinder 22 is used, and the pressure receiving chambers 8a, 9c are used.
It is good also as composition which supplies oil pressure to a and 12c.

The forward / reverse switching operation means is not limited to the lever, but may be a push button capable of selecting any of the forward travel position, the reverse travel position, and the neutral position. Shift switch 3
2 is a contact point operated by a push button.

The accelerator operation means is the accelerator pedal 2
The lever is not limited to 5 and may be a manually operated lever. ○
The cargo handling operation means is not limited to the lift lever 33 and the tilt lever 34, and may include a lever required for other cargo handling operations depending on the type of forklift.

The throttle opening (THlif) for cargo handling
t) may be set based only on the operation amount of the lift lever 33. The present invention is not limited to a forklift, and may be applied to other industrial vehicles equipped with a hydraulic device for cargo handling, such as a shovel loader.

A dry hydraulic clutch may be used instead of the wet hydraulic clutch as both clutches 8 and 9. Various maps may be stored in the ROM 43 in advance. In this case, the CPU 42 does not need to set various maps.

The inching pedal 26 may be omitted to make it impossible to run at a very low speed by manual operation. Inventions (technical ideas) other than those described in the claims that can be grasped from the embodiment will be described below together with their effects.

(1) In the invention according to any one of claims 1 to 4, the control means determines the relationship between the operation amount of the brake operation means and the clutch pressure for obtaining the corresponding braking force. The clutch pressure is obtained based on the map or the arithmetic expression shown, and the control valve is controlled so that the clutch pressure is obtained. In this case, control for obtaining an appropriate braking force corresponding to the brake operation amount is simplified.

(2) In the invention according to claim 2,
The value of the clutch pressure on the braking side corresponding to the brake operation force is
It is set lower than the value of the clutch pressure corresponding to the brake operation force during normal running. In this case, the stability of the vehicle during the HAT can be further improved.

(3) In the invention as set forth in claim 2 or claim 3, the control means determines that the relationship between the engagement pressure of the clutch for applying the braking force and the operation amount of the brake operating means is determined during normal running and during HAT. Then, the clutch pressure corresponding to the operation amount of the brake operating means is calculated from the same map or arithmetic expression, and when the clutch pressure is larger than the upper limit value, control is performed so that the upper limit value is obtained. In this case, there is no need to provide a separate map or arithmetic expression for HAT.

(4) In the invention as set forth in any one of claims 1 to 4, the control means may adjust the engine speed to the vehicle speed and the weight of the load in advance when the weight of the load is equal to or greater than a predetermined value. Control is performed so as to be equal to or less than the upper limit set accordingly. In this case, in addition to the corresponding effects of claims 1 to 4, in addition to a load having a certain weight or more, the load does not move at a high speed at a high vehicle speed, and the stability of the vehicle is improved. improves.

(5) In the invention according to any one of claims 1 to 5 or (4), the control means may be an H
At the time of AT, the vehicle speed is controlled so as to be lower than the vehicle speed during normal running. In this case, in addition to the effect corresponding to claims 1 to 5 or the effect described in (4), since the maximum speed during HAT is regulated to be lower than the maximum vehicle speed during normal driving, the center of gravity is high. As a result, the stability of the vehicle when a braking force is applied during a HAT with low stability is improved.

(6) In the invention as set forth in any one of (1) to (8), (4) or (5), the control means may be configured to determine that the load in the HAT is rising while the determination means is in normal running. Even if it is determined that the clutch on the traveling side is not in the fully engaged state and is maintained in the half clutch state, the target engine speed is set to the target engine speed and the operation amount of the cargo handling means corresponding to the operation amount of the accelerator operation means. The target engine speed is set to a larger value than the target engine speed set on the basis of this, and control is performed so as to reach the target engine speed.After the load is stopped, the traveling side clutch is fully engaged and normal running is performed. Is controlled so as to shift to. In this case, in addition to the effect corresponding to claim 1 to claim 8 or the effect described in (4) or (5), a shock caused by the clutch being changed from the half-clutched state to the fully engaged state while the load is rising. Can be reliably prevented. Further, after the lifting of the load is stopped, the engine speed at the target vehicle speed can be reached in a short time when the traveling side clutch is fully engaged to shift to normal traveling.

[0160]

As described in detail above, claims 1 to 1 are provided.
According to the invention described in 2, the speed control at the time of HAT can be automatically performed, and the stability of the vehicle at the time of transition from normal driving to HAT or at the time of HAT can be improved.

According to the first to fourth aspects of the present invention, it is possible to prevent a large sudden braking force from acting during a HAT in which the stability is small due to a high center of gravity, thereby improving the stability of the vehicle during the HAT. it can.

According to the second aspect of the present invention, since the braking force is obtained by simultaneous engagement of the forward clutch and the reverse clutch, there is no need to provide a regular brake for braking, and the number of assembly steps is reduced accordingly. it can.

According to the third aspect of the present invention, control is simplified as compared with a configuration in which a braking force is obtained by simultaneous engagement of the forward clutch and the reverse clutch. According to the fourth aspect of the invention, the stability of the vehicle can be improved in response to a change in the center of gravity of the vehicle without performing complicated processing for calculating the center of gravity of the vehicle.

According to the fifth aspect of the present invention, the load is not moved up at high speed in a state where the vehicle speed is high in a state where there is a load having a certain weight or more, and the stability of the vehicle is improved.
According to the invention described in claims 6 to 8, since the maximum speed during HAT is regulated to be lower than the maximum vehicle speed during normal running, the braking force during HAT with a high center of gravity and low stability is reduced. The stability of the vehicle when acting is improved.

According to the seventh aspect of the present invention, since the target vehicle speed at the time of HAT has an upper limit set in accordance with the lift, the stability of the vehicle at the time of cargo handling when the center of gravity of the vehicle becomes high is improved. improves.

According to the eighth aspect of the present invention, since the target vehicle speed at the time of HAT has an upper limit set in accordance with the lift and the weight of the load, the target vehicle speed at the time of loading and running when the vehicle has a high center of gravity is set. Stability is further improved.

According to the ninth aspect of the present invention, it is possible to reliably prevent the occurrence of a shock caused by the clutch changing from the half-clutch state to the fully engaged state while the load is rising. Also,
After the lifting of the load is stopped, the engine speed at the target vehicle speed can be reached in a short time when the traveling-side clutch is brought into the fully engaged state to shift to normal traveling.

According to the tenth aspect of the present invention, it is not necessary to operate the brake operating means with a large operating force for braking, so that the brake operation becomes easy and the vehicle suddenly stops when the operation of the brake operating means is stopped. There is no danger of being accelerated.

According to the eleventh and twelfth aspects of the present invention, since the vehicle does not shift to the HAT when the vehicle speed is equal to or higher than the predetermined speed, the stability of the vehicle during the HAT is improved. According to the twelfth aspect, there is no possibility that the speed exceeds the upper limit speed during HAT, and the stability of the vehicle during HAT is further improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment.

FIG. 2 is a flowchart for explaining normal traveling, HAT determination, and the like.

FIG. 3 is a flowchart illustrating an operation when setting a target vehicle speed.

FIG. 4 is a flowchart for explaining a braking operation during HAT.

FIG. 5 is a flowchart for explaining the operation of a parking brake.

FIG. 6 is a map showing a relationship between a brake pedal pressure and a braking-side clutch pressure.

FIG. 7 is a diagram illustrating a part of a flowchart according to the second embodiment;

FIG. 8 is a map showing a relationship between a brake pedal pressure and a braking-side clutch pressure.

FIG. 9 is a map showing the relationship between the clutch pressure upper limit, the lift, and the weight of the load.

10A is a schematic diagram illustrating an arrangement of a lift switch, and FIG. 10B is a schematic diagram illustrating an arrangement of a lift sensor.

FIG. 11 is a diagram showing a part of a flowchart according to the third embodiment;

FIG. 12 is a map showing a relationship between an upper limit of a target vehicle speed and a lift.

FIG. 13 is a flowchart of the fourth embodiment.

FIG. 14 is a map showing the relationship between the upper limit of the engine speed, the vehicle speed, and the weight of the load.

FIG. 15 is a map showing a relationship between a target engine speed and a control valve opening.

FIG. 16 is a schematic configuration diagram of a sixth embodiment.

FIG. 17 is a flowchart of the seventh embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Torque converter, 3 ... Transmission, 5
a: drive wheel, 8: forward clutch, 9: reverse clutch, 1
0: forward clutch valve as control valve, 11: reverse clutch valve, 19: vehicle speed sensor as vehicle speed detecting means, 20: hydraulic pump as cargo handling pump, 25
... Accelerator pedal as accelerator operating means, 27 ... Brake pedal as brake operating means, 28 ... Accelerator sensor as accelerator operating amount detecting means, 33 ... Lift lever as cargo handling operating means, 34 ... Tilt lever, 35 ... Cargo handling Lift lever sensor as operation amount detecting means, 36... Tilt switch similarly, 42... CPU constituting target vehicle speed setting means and target engine speed setting means, and determining means and control means.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02D 29/04 F16D 25/14 640K F-term (Reference) 3D041 AA33 AA37 AA66 AA71 AA76 AB07 AC01 AC09 AC18 AC26 AD02 AD04 AD10 AD23 AD32. FA10 3J057 AA03 BB03 GA57 GB05 GB29 GB36 GB39 GE05 GE07 HH04 JJ01

Claims (12)

[Claims] 1. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to drive wheels via a torque converter, and increasing and decreasing the hydraulic pressure in a pressure receiving chamber of each clutch to change the engagement state. A control valve for adjusting; an accelerator operation amount detecting means for detecting an operation amount of an accelerator operation means; a target vehicle speed setting means for the accelerator operation amount; a target engine speed setting means for the accelerator operation amount; and a traveling speed of the vehicle. Speed detecting means for detecting the load, a loading pump driven by the engine, a loading operation amount detecting means for detecting an operation amount of the loading operation means operated for performing the loading operation, a brake operating means, a loading operation Means for setting the target engine speed with respect to the amount, and normal traveling based on the detection signals of the accelerator operation amount detection means and the cargo operation amount detection means. Judgment means for judging whether the vehicle is in cargo handling, and when the judgment means judges that the vehicle is traveling normally, the clutch on the traveling side is set to a fully engaged state and controlled to a target engine speed corresponding to the operation amount of the accelerator operation means, If the determining means determines that the cargo handling is traveling, the target engine speed is controlled based on the operation amount of the cargo handling operation means, and the clutch on the traveling side is set to the half-clutch state, and the operation amount of the accelerator operation means is corresponded. A cargo handling and travel control device for an industrial vehicle, comprising: a control means for controlling an engagement pressure of a clutch such that the target vehicle speed is attained. A cargo handling and traveling control device for an industrial vehicle that performs braking so as to be equal to or less than a predetermined upper limit value. 2. The cargo handling and traveling control device for an industrial vehicle according to claim 1, wherein said control means controls said control valves so as to obtain said braking force by simultaneous engagement of said forward clutch and reverse clutch. 3. The transmission incorporates a hydraulic braking clutch, and the control means controls a control valve that adjusts an engagement state by increasing or decreasing a hydraulic pressure in a pressure receiving chamber of the braking clutch during the braking. The cargo handling and traveling control device for an industrial vehicle according to claim 1. 4. The industrial vehicle according to claim 2, wherein said control means controls said control valve so as to apply a braking pressure equal to or less than a preset upper limit in accordance with the lift and weight of the load. Cargo handling and travel control equipment. 5. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to drive wheels via a torque converter, and increasing and decreasing the hydraulic pressure in a pressure receiving chamber of each clutch to change the engagement state. A control valve for adjusting; an accelerator operation amount detecting means for detecting an operation amount of an accelerator operation means; a target vehicle speed setting means for the accelerator operation amount; a target engine speed setting means for the accelerator operation amount; and a traveling speed of the vehicle. Speed detection means for detecting the load, a loading pump driven by the engine, a loading operation amount detecting means for detecting the operation amount of the loading operation means operated for performing the loading operation, and a target engine rotation with respect to the loading operation amount Number setting means, and determining whether the vehicle is traveling normally or not based on the detection signals of the accelerator operation amount detection means and the cargo operation amount detection means. Determining means, when the determining means determines that the vehicle is traveling normally, controls the forward clutch to a fully engaged state to control the target engine speed corresponding to the operation amount of the accelerator operation means, and When it is determined, the target engine speed is controlled to the target engine speed set based on the operation amount of the cargo handling operation means, and the clutch on the traveling side is set to the half-clutch state, and the target vehicle speed corresponds to the operation amount of the accelerator operation means. In a cargo handling and travel control device for an industrial vehicle, comprising: a control unit for controlling an engagement pressure of a clutch.
A cargo handling and travel control device for an industrial vehicle that controls an engine speed to be equal to or less than an upper limit set in advance according to a vehicle speed and a weight of a load. 6. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to driving wheels via a torque converter, and increasing and decreasing the hydraulic pressure in a pressure receiving chamber of each clutch to change the engagement state. A control valve for adjusting; an accelerator operation amount detecting means for detecting an operation amount of an accelerator operation means; a target vehicle speed setting means for the accelerator operation amount; a target engine speed setting means for the accelerator operation amount; and a traveling speed of the vehicle. Speed detection means for detecting the load, a loading pump driven by the engine, a loading operation amount detecting means for detecting the operation amount of the loading operation means operated for performing the loading operation, and a target engine rotation with respect to the loading operation amount Number setting means, and determining whether the vehicle is traveling normally or not based on the detection signals of the accelerator operation amount detection means and the cargo operation amount detection means. Determining means, when the determining means determines that the vehicle is traveling normally, controls the forward clutch to a fully engaged state to control the target engine speed corresponding to the operation amount of the accelerator operation means, and When it is determined, the target engine speed is controlled to the target engine speed set based on the operation amount of the cargo handling operation means, and the clutch on the traveling side is set to the half-clutch state, and the target vehicle speed corresponds to the operation amount of the accelerator operation means. And a control device for controlling the engagement pressure of the clutch, wherein the control means controls the vehicle speed during loading / unloading to be lower than the vehicle speed during normal running. Cargo handling and travel control equipment. 7. The cargo handling and traveling control device for an industrial vehicle according to claim 6, wherein an upper limit of the vehicle speed is set in accordance with a lift. 8. The cargo handling and traveling control device for an industrial vehicle according to claim 6, wherein an upper limit is set for the vehicle speed in accordance with the lift and the weight of the load. 9. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to drive wheels via a torque converter, and increasing and decreasing the hydraulic pressure in a pressure receiving chamber of each clutch to change the engagement state. A control valve for adjusting; an accelerator operation amount detecting means for detecting an operation amount of an accelerator operation means; a target vehicle speed setting means for the accelerator operation amount; a target engine speed setting means for the accelerator operation amount; and a traveling speed of the vehicle. Speed detection means for detecting the load, a loading pump driven by the engine, a loading operation amount detecting means for detecting the operation amount of the loading operation means operated for performing the loading operation, and a target engine rotation with respect to the loading operation amount Number setting means, and determining whether the vehicle is traveling normally or not based on the detection signals of the accelerator operation amount detection means and the cargo operation amount detection means. Determining means, when the determining means determines that the vehicle is traveling normally, controls the forward clutch to a fully engaged state to control the target engine speed corresponding to the operation amount of the accelerator operation means, and When it is determined, the target engine speed is controlled to the target engine speed set based on the operation amount of the cargo handling operation means, and the clutch on the traveling side is set to the half-clutch state, and the target vehicle speed corresponds to the operation amount of the accelerator operation means. A cargo handling and traveling control device for an industrial vehicle, comprising: control means for controlling the engagement pressure of a clutch. The clutch on the side is held in a half-clutch state without being fully engaged, and the target engine speed is set to a target engine speed corresponding to the operation amount of the accelerator operation means. The target engine speed is set to be larger than the target engine speed set based on the operation amount of the operating means, and control is performed so as to reach the target engine speed. A cargo handling and travel control device for an industrial vehicle that performs control to shift to normal travel as an engaged state. 10. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to driving wheels via a torque converter, and increasing and decreasing the oil pressure in a pressure receiving chamber of each clutch to change an engaged state. A control valve for adjusting; an accelerator operation amount detecting means for detecting an operation amount of an accelerator operation means; a target vehicle speed setting means for the accelerator operation amount; a target engine speed setting means for the accelerator operation amount; and a traveling speed of the vehicle. Interlocking with the operation of the vehicle speed detecting means for detecting the load, the loading pump driven by the engine, the loading operation amount detecting means for detecting the operation amount of the loading operation means operated for performing the loading operation, and the brake operating means Service brake that is actuated in response to the load, target engine speed setting means for the load operation amount, accelerator operation amount detection means, and load operation Determining means for determining whether the vehicle is traveling normally or unloading based on a detection signal of the amount detecting means; and, when the determining means determines that the vehicle is traveling normally, the clutch on the traveling side is set to a fully engaged state to operate the accelerator operation means. The target engine speed is controlled to a target engine speed corresponding to the above, and when the determination means determines that the cargo handling is traveling, the target engine speed is set to a target engine speed set based on the operation amount of the cargo handling operation means, and the traveling side clutch is in a half clutch state. And a control means for controlling an engagement pressure of a clutch so as to attain a target vehicle speed corresponding to an operation amount of the accelerator operation means. When the brake operating means is operated, the target vehicle speed is set to 0 and the engaging pressure of the forward clutch is controlled regardless of the operation amount of the accelerator operating means. Cargo handling and running controller for the industrial vehicle. 11. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to driving wheels via a torque converter, and increasing and decreasing the hydraulic pressure in a pressure receiving chamber of each clutch to change the engagement state. A control valve for adjusting; an accelerator operation amount detecting means for detecting an operation amount of an accelerator operation means; a target vehicle speed setting means for the accelerator operation amount; a target engine speed setting means for the accelerator operation amount; and a traveling speed of the vehicle. Speed detection means for detecting the load, a loading pump driven by the engine, a loading operation amount detecting means for detecting the operation amount of the loading operation means operated for performing the loading operation, and a target engine rotation with respect to the loading operation amount Number setting means, and determining whether the vehicle is traveling normally or not based on detection signals from the accelerator operation amount detection means and the cargo operation amount detection means. When the determining means determines that the vehicle is traveling normally, the clutch on the traveling side is brought into a completely engaged state and controlled to a target engine speed corresponding to the operation amount of the accelerator operating means. If it is determined that the target engine speed is set to the target engine speed set based on the operation amount of the cargo handling operation means, and the forward clutch is set to the half-clutch state, and the target vehicle speed corresponding to the operation amount of the accelerator operation means is obtained. And a control device for controlling the engagement pressure of the clutch as described above, wherein the control means controls the accelerator operation amount detection means and the cargo operation operation amount when the vehicle speed is equal to or higher than a predetermined vehicle speed. Even if the detection signal of the means satisfies the conditions for cargo handling, the cargo handling and running of the industrial vehicle is controlled so as not to shift to cargo handling but to continue the control of normal running. The control device. 12. The cargo handling and traveling control device for an industrial vehicle according to claim 11, wherein the predetermined vehicle speed is set to be equal to an upper limit vehicle speed during cargo handling traveling.