JP2002027609A - Travel controller for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent braking distance from becoming long against the driver's will, during braking in a state that slipping of drive wheels involved in braking cannot be detected. SOLUTION: Drive wheels 12 are braked by the regenerative braking of a drive motor 26, based on the switchback operation on an acceleration lever 22, and further slipping velocity ΔVD for detecting slipping of the drive wheels 12 is determined from the number of front wheel revolutions NLF (NRF) and the number of rear wheel revolutions ND1 (ND2). When the slipping velocity ΔVD falls below a reference slipping velocity ΔVD2, a left and a right hydraulic brake devices 16L and 16R are controlled to brake the left and right front wheels 11L and 11R. If the number of front wheel revolutions NLF (NRF) can be no longer detected, the left and right front wheels 11L and 11R are braked, when the acceleration lever 22 is switchback-operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel control device for braking driven wheels of an industrial vehicle such as a reach-type forklift truck when the driven wheels slip on a road surface.

[0002]

2. Description of the Related Art Conventionally, a reach-type forklift truck (hereinafter simply referred to as a reach forklift) is driven by a battery driven electric motor.
The vehicle travels simply by driving the driving wheels. Also,
In a reach forklift, a vehicle is braked by braking a drive wheel. The braking of the drive wheels is performed mainly by regenerative braking of the electric motor which is controlled based on the switchback operation of the accelerator lever.

[0003] When the driving wheels are braked by regenerative braking while the vehicle is traveling on a slippery road surface, the driving wheels may slip on the road surface. For this reason, the braking distance may be long, or the rear portion of the vehicle body may be swung right and left.

A reach forklift for solving such a problem has been proposed in Japanese Patent Application Laid-Open No. H11-122721. In this reach forklift, when the rear wheels are locked and slip on the road surface during braking of the drive wheels, the left and right front wheels are driven in reverse rotation by auxiliary motors (electric motors) provided respectively. For this reason, when only the drive wheels are braked, the vehicle is also braked by the left and right front wheels when the drive wheels slip, so that the braking distance becomes longer and the rear part of the vehicle body is hardly swung right and left.

[0005]

In the above-described reach forklift, an assist is provided based on a comparison result between a front wheel speed signal obtained by detecting the rotational speeds of the left and right front wheels and a rear wheel speed command signal which becomes "0" during braking. Drive the motor in reverse. Therefore, tachometers for detecting the rotation speeds of the left and right front wheels are provided at the tips of the left and right reach legs, respectively.

If the tachometer fails, the left and right front wheels are not braked even if the driving wheels lock and slip on the road surface during braking. For this reason, if the operator performs the brake operation as usual without knowing that the tachometer is out of order, the braking distance may be undesirably increased.

This is not only the case where the driving wheels are braked by regenerative braking of the electric motor, but also the case where the driving wheels are braked by a mechanical brake which is operated by operating a brake pedal. This is a problem that occurs even when braking is performed.

[0008] Not only reach forklifts,
When the braked drive wheel slips on the road surface,
This is a problem common to industrial vehicles in which the driven wheels are braked.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a brake system which is capable of detecting a slip of a driving wheel with respect to a road surface due to the braking operation. It is an object of the present invention to provide a travel control device for an industrial vehicle that can prevent the distance from becoming undesirably long.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 detects a slip of a drive wheel braked on a road surface based on an operation of a brake operating means operated by an operator. In the travel control device for an industrial vehicle including braking control means for braking a driven wheel based on the detection result, the braking control means may not detect a slip of the drive wheel with respect to a road surface.
The driven wheel is braked based on the operation of the brake operating means.

According to the first aspect of the invention, when the driving wheel is braked based on the operation of the brake operating means, the driven wheel is braked when the driving wheel slips on the road surface. Further, when the slip of the drive wheel cannot be detected, when the brake operating means is operated, the drive wheel is braked and the driven wheel is braked. Therefore, in a state where the slip of the drive wheel due to the braking cannot be detected, the driven wheel is braked regardless of the slip of the drive wheel.

According to a second aspect of the present invention, in the first aspect, the braking control means controls a hydraulic brake device to brake the driven wheels.
According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, when the drive wheel slips, the driven wheel is braked by the hydraulic brake device. Therefore, power consumption can be reduced as compared with the case where the driven wheel is reversely driven by the auxiliary electric motor to perform braking.

According to a third aspect of the present invention, in the first or second aspect, the brake operating means is an accelerator lever for controlling operation of an electric motor for regeneratively braking the drive wheels. The gist of the invention is that the braking control unit brakes the driven wheel based on the switchback operation of the accelerator lever.

According to the invention described in claim 3, according to claim 1 of the present invention,
Alternatively, in addition to the function of the invention described in claim 2, when the accelerator lever is switched back, the driving wheels are braked by regenerative braking of the electric motor, and the driven wheels are braked when the driving wheels slip. . Then, when the slip of the drive wheel cannot be detected, the driven wheel is braked based on the switchback operation of the accelerator lever regardless of the slip of the drive wheel. Therefore, even if the slip of the driving wheels cannot be detected when the vehicle is braked by the switchback operation of the accelerator lever, the braking distance does not increase unexpectedly.

According to a fourth aspect of the present invention, in the operation of the third aspect of the present invention, in the travel control device for an industrial vehicle according to the third aspect, the driving wheels are driven by a regenerative braking of the electric motor with respect to a road surface. The gist of the invention is to provide a braking force control means for detecting a slip and controlling a braking force by regenerative braking of the electric motor so as to limit the slip.

According to the invention set forth in claim 4, according to claim 3,
In addition to the operation of the invention described in the above, when the driving wheels are braked by the regenerative braking of the electric motor, the braking force of the electric motor is controlled so as to limit the slip of the driving wheels. Accordingly, the driving wheels do not unnecessarily slip on the road surface during braking, so that the braking distance can be further shortened and the posture of the vehicle body can be further stabilized.

According to a fifth aspect of the present invention, in the driving control apparatus for an industrial vehicle according to the first or second aspect, the brake operating means is provided with the brake operating means. A brake pedal for operating a mechanical brake device for braking a drive wheel, wherein the brake control means brakes the driven wheel when the brake pedal is operated.

According to the invention described in claim 5, according to claim 1,
Alternatively, in addition to the operation of the invention described in claim 2, when the brake pedal is operated, the mechanical brake device operates to brake the drive wheels, and when the drive wheels slip, the driven wheels are also braked. Further, when the slip of the drive wheel cannot be detected, the driven wheel is braked based on the operation of the brake pedal regardless of the slip of the drive wheel. Therefore, even if the slip of the drive wheels cannot be detected during the braking of the vehicle by the operation of the brake pedal, it is possible to prevent the braking distance from becoming long unintentionally.

The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein
6. The travel control device for an industrial vehicle according to claim 5, wherein the braking control unit detects a rotation speed of the driven wheel and a rotation speed of the driven wheel. The gist of the present invention is to provide a drive wheel rotational speed detecting means for detecting the slip of the driven wheel with respect to the road surface from the rotational speed of the driven wheel and the rotational speed of the drive wheel.

According to the invention of claim 6, according to claim 1,
In addition to the effect of the invention described in any one of claims to 5, the slip of the drive wheel with respect to the road surface is detected from the rotation speed of the driven wheel and the rotation speed of the drive wheel. Then, even if the slip of the driving wheel cannot be detected due to the failure of one of the driven wheel rotation speed detecting means and the driving wheel rotation speed detecting means or the disconnection of the signal line thereof, regardless of the slip of the driving wheel during the brake operation. The driven wheels are braked together with the drive wheels.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a travel control device for a reach type forklift truck will be described below with reference to FIGS.

As shown in FIGS. 2 and 3, a reach type forklift truck 10 (hereinafter, referred to as a reach forklift) as an industrial vehicle has front and rear wheels 11L and 11R as a pair of left and right driven wheels, and drive steering wheels as drive wheels. The vehicle body 14 includes a rear wheel including a drive wheel 12 (hereinafter simply referred to as a drive wheel) and a caster 13.

The front portion of the vehicle body 14 is constituted by a pair of left and right reach legs 15L, 15R. Each reach leg 15
L and 15R support the front wheels 11L and 11R at their tips, respectively. The front wheels 11L, 11R are provided with hydraulic brake devices 16L, 16R, respectively. A mast device 17 is supported between the reach legs 15L and 15R so that the mast device 17 can reach forward and backward. The mast device 17 performs a reach operation by a reach cylinder 18 provided on the lower rear side of the vehicle body 14.

A driver's seat 19 is provided on the rear right side of the vehicle body 14. An operation panel 20 is provided in front of the driver's seat 19, and a handle 21 is provided on the left side of the driver's seat 19. The handle 21 is provided to steer the drive wheel 12. The operation panel 20 includes an accelerator lever 22 as a brake operation means and a plurality of cargo handling levers 23.
Are provided. A brake pedal 24 for applying a brake to the driving wheel 12 is provided on the floor of the driver's seat 19.
Is provided.

On the rear left side of the vehicle body 14, the drive wheels 12
Is provided with a drive unit 25 for driving. The drive unit 25 includes a traveling motor 26 as an electric motor and a wheel supporting portion 27.
The driving wheels 12 supported by the motor are driven by a traveling motor 26. The traveling motor 26 is an AC induction motor. The casters 13 are supported below the driver's seat 19.

Next, a description will be given of a hydraulic device constituting a travel control device of the reach forklift. As shown in FIG. 1, the hydraulic device includes an oil tank 30, a hydraulic motor 3
1, an oil pump 32, a brake control valve unit 33, and the like.

The hydraulic motor 31 drives an oil pump 32 to supply hydraulic oil in an oil tank 30 to a brake control valve unit 33 and an oil control valve unit 34 at a predetermined oil pressure. The oil control valve unit 34 is a unit in which valves operated by the respective cargo handling levers 23 are integrated, and supplies and discharges hydraulic oil to a lift cylinder, a reach cylinder, and a tilt cylinder (not shown).

The brake control valve unit 33 is formed by integrating a pressure reducing valve, a shut-off valve, a linear solenoid valve, an accumulator 33a and the like (not shown). The brake control valve unit 33 accumulates hydraulic oil supplied from the oil pump 32 at a predetermined hydraulic pressure in the accumulator 33a, and controls the hydraulic pressure output to each of the hydraulic brake devices 16L and 16R by electric control. Each of the hydraulic brake devices 16L and 16R brakes the front wheels 11L and 11R with a braking force corresponding to the hydraulic pressure of the supplied hydraulic oil.

Next, an electric device constituting a travel control device of the reach forklift will be described. As shown in FIG. 1, the electric device includes an accelerator opening sensor 40, traveling direction detection switches 41a and 41b, a motor speed sensor 42.
a, 42b, a steering angle sensor 43, a pressure switch 44, front wheel speed sensors 45L and 45R, a controller 46, and the like.

In this embodiment, the controller 46 is a braking force control unit and a slip detection unit. The motor rotation speed sensors 42a and 42b and the controller 46 constitute driving wheel rotation speed detection means, and the front wheel rotation speed sensor 45
L, 45R and the controller 46 constitute a driven wheel rotational speed detecting means. Also, the hydraulic motor 31, the oil pump 3
2. Brake control valve unit 33, motor speed sensors 42a, 42b, front wheel speed sensors 45L, 45R
And the controller 46 constitute a braking control means. Further, the hydraulic brake devices 16L and 16R, the traveling motor 2
6. Hydraulic motor 31, oil pump 32, brake control valve unit 33, accelerator opening sensor 40, traveling direction detection switches 41a and 41b, motor speed sensor 4
2a, 42b, steering angle sensor 43, pressure switch 44,
Front wheel speed sensors 45L, 45R and controller 46
Etc. constitute a travel control device.

An accelerator opening sensor 40 is disposed below the operation panel 20 and detects an accelerator opening ACC of an accelerator lever 22 which is operated forward or backward from a neutral position.
The detection signal is output to the controller 46.

The traveling direction detecting switches 41a and 41b are
Both are turned off when the accelerator lever 22 is at the neutral position. The switch 41a is turned on from off to on only when the accelerator lever 22 is operated from the neutral position to the forward side, and outputs the forward signal SF to the controller 46. The switch 41b is turned on from off and outputs a reverse signal SR to the controller 46 only when the accelerator lever 22 is operated from the neutral position to the reverse side.

The motor rotation speed sensors 42a and 42b detect the rotation speed of a gear (not shown) fixed to the output shaft of the traveling motor 26 as an object to be detected. The motor rotation speed sensors 42a and 42b output motor rotation speeds NM1 and NM2 (where NM1 = N
M2), that is, the rear wheel rotation speed ND which is the rotation speed of the drive wheel 12
Pulse signals corresponding to 1, ND2 (where ND1 = ND2) are generated and output to the controller 46, respectively. The motor speed sensors 42a and 42b are provided such that the pulse signals are output at timings when the phases are shifted by 90 ° and with the phase shift relationship reversed according to the rotation direction of the traveling motor 26. Have been.

The steering angle sensor 43 is connected to the drive unit 25.
A steering angle θ of the drive wheel 12 that is steered to the right or left from a straight running state is detected by using a gear (not shown) that rotates together with the gear to be detected, and a detection signal is output to the controller 46.

The pressure switch 44 is provided in the brake control valve unit 33, and outputs a detection signal to the controller 46 when the oil pressure of the accumulator 33a falls below a predetermined oil pressure.

The front wheel rotation speed sensors 45L and 45R are provided on the reach legs 15L and 15R, and detect detected parts provided on the front wheels 11L and 11R, respectively. And
The front wheel rotation speed sensor 45L receives a pulse signal corresponding to the front wheel rotation speed NLF, which is the rotation speed of the front wheel 11L, and the front wheel rotation speed sensor 45R receives a pulse signal corresponding to the front wheel rotation speed NRF, which is the rotation speed of the front wheel 11R. Output to

The controller 46 includes a control circuit (not shown) composed of a microcomputer, a three-phase inverter circuit, a solenoid valve driving circuit, and the like. The controller 46 executes the various control programs stored in advance by the microcomputer to execute the traveling motor 26,
The control of the hydraulic motor 31 and the brake control valve unit 33 is performed. The controller 46 supplies a three-phase alternating current whose current value and frequency are controlled to the traveling motor 26,
A predetermined drive current is supplied to the hydraulic motor 31. Further, a drive current corresponding to a target braking force of the hydraulic brake devices 16L and 16R is supplied to the brake control valve unit 33.

The traveling motor 26 rotates forward or backward with a driving torque or a braking torque according to the current value and frequency of the three-phase alternating current supplied from the controller 46. The hydraulic motor 31 is rotated by a drive current supplied from the controller 46.

The brake control valve unit 33 supplies a hydraulic pressure according to the drive current supplied from the controller 46 to each of the hydraulic brake devices 16L and 16R. The controller 46 operates the hydraulic motor 31 when each of the cargo handling levers 23 is operated, and controls the hydraulic motor 31 when the detection signal is input from the pressure switch 44 even when each of the cargo handling levers 23 is not operated. drive.
Further, the controller 46 includes a motor rotation speed sensor 42
a, 42b, the direction of rotation of the traveling motor 26 is forward or reverse, that is, the direction in which the drive wheel 12 rotates forward or reverse. Determine if there is.

The controller 46 controls the running of the vehicle based on each signal according to the control program. The controller 46 performs the following controls in the traveling control.

(Motor operation control) The controller 46
Motor operation control for controlling the traveling motor 26 is performed based on the accelerator opening ACC, the forward and reverse signals SF and SR, and the motor speeds NM1 and NM2.

As the motor operation control, the controller 46
Determines whether the accelerator lever 22 is being operated on the forward side or the reverse side based on the forward and reverse signals SF and SR. Further, it is determined from the motor rotation speeds NM1 and NM2 whether the rotation direction of the traveling motor 26 at that time is forward rotation or reverse rotation. And the accelerator lever 2
The rotation direction and the target torque are set from the accelerator opening ACC and the motor speed NM1 (= NM2) at that time according to the side on which the motor 2 is operated, and the traveling motor 26 is operated at the target torque. The controller 46 includes forward and reverse signals SF and SR, an accelerator opening ACC and a motor speed N.
The target torque is set using a map in which the target torque is set corresponding to M1 (NM2).

More specifically, as the motor operation control, when the forward signal SF is input and the rotation direction of the traveling motor 26 is forward rotation, the controller 46 controls the accelerator opening ACC and the motor rotation speed at that time. When the value of the map set corresponding to NM1 (NM2) is positive, the target drive torque is set as the target torque. On the other hand, when the value of the map corresponding to the accelerator opening ACC and the motor speed NM1 (NM2) is negative, the target braking torque is set as the target torque. Similarly, the controller 46 performs the same control when the reverse signal SR is input and the rotation direction of the traveling motor 26 is reversed.

As the motor operation control, the controller 46 receives the reverse signal SR while the rotation direction of the traveling motor 26 is in the normal rotation, or receives the forward signal SF while the rotation direction is in the reverse direction. In other words, it is determined that the accelerator lever 22 has been switched back. At this time, the accelerator opening ACC and the motor speed NM1 at that time are
The target braking torque corresponding to (NM2) is set using the map, and the traveling motor 26 is operated at the target braking torque.

By this motor operation control, the controller 46 drives the drive wheels 12 with a drive torque corresponding to the operation direction of the accelerator lever 22, the accelerator opening ACC, and the vehicle speed to run the vehicle. Further, when the accelerator lever 22 is switched back to the reverse side or the forward side while the vehicle is moving forward or backward, the braking torque of the traveling motor 26 according to the accelerator opening ACC to the backward or forward side is obtained. The driving wheels 12 are braked to brake the vehicle.

(Regenerative braking force control)
6 shows the front wheel rotation speeds NLF and NRF and the rear wheel rotation speed N when a switchback operation is performed during the motor operation control.
The slip of the drive wheels 12 is detected based on D1 and ND2, and regenerative braking force control (traction control during braking) for limiting the braking torque of the traveling motor 26 is performed.

The controller 46 performs regenerative braking force control.
Is calculated from the front wheel rotation speeds NLF and NRF using the radius of the front wheels 11L and 11R stored in advance.
The front wheel speeds VLF and VRF, which are the moving speeds of the vehicle, are obtained. At this time, the controller 46 calculates the left or right front wheel speed VLF (or VRF) when the vehicle is running straight,
Also, when the vehicle is in a turning state, the front wheels 1 on the outside of the turn are turned off.
A 1L (or 11R) front wheel speed VLF (or VRF) is obtained. This is the left or right front wheel 11L (or 11R)
Front wheel speed VLF (or VR)
F).

The controller 46 determines the rear wheel speed N
The rear wheel speed VD is obtained from D1 (ND2) using the radius of the drive wheel 12 stored in advance. This rear wheel speed VD is
When there is a slip between the driving wheel 12 and the road surface, the traveling speed of the driving wheel 12 becomes smaller than the moving speed of the driving wheel 12 by the amount of the slip.

Next, the controller 46 calculates the front wheel speed VLF (or VRF) from the ratio between the turning radius of the front wheel 11L (11R) and the turning radius of the drive wheel 12 according to the steering angle θ at that time. Multiplied by the determined correction coefficient, the front wheel speed VLF
(Or VRF) is converted to the moving speed of the drive wheel 12 to obtain a converted wheel speed VDP.

The controller 46 calculates a speed difference (VD) obtained by subtracting the converted rear wheel speed VDP from the rear wheel speed VD.
-VDP) to the slip velocity ΔVD (= (VD-VDP) <0) for detecting slip of the drive wheels 12 on the road surface.
Asking. That is, the slip speed ΔVD is
The driving force on the road surface exceeds the maximum braking force determined by the driving wheel weight and the coefficient of friction with the road surface.
2 is the speed difference by which the vehicle slips on the road surface and is smaller than the moving speed of the drive wheels 12.

The controller 46 performs the regenerative braking force control when the slip speed ΔVD falls below the preset reference slip speed ΔVD0 (<0).
2 determines that the vehicle is slipping on the road surface, and limits the braking torque of the traveling motor 26 so that the slip speed ΔVD falls within a predetermined appropriate range.

It should be noted that even during power running of the vehicle, drive force control (traction control during power running) for limiting the target drive torque of the traveling motor 26 when slippage of the drive wheels 12 is detected.
Is performed.

(Front wheel braking control)
6 controls the left and right hydraulic brake devices 16 by controlling the brake control valve unit 33 during the regenerative braking force control.
L, 16R are operated to perform front wheel braking control for braking the left and right front wheels 11L, 11R.

As the front wheel braking control, the controller 46
When the front wheel speed NLF (NRF) is equal to or greater than a preset stop determination value ND0, the slip speed ΔV
Once D falls below the reference slip speed ΔVD0, the brake control valve unit 33 is controlled to operate the left and right hydraulic brake devices 16L and 16R. At this time, the controller 46 supplies a drive current of a preset magnitude to the brake control valve unit 33, and controls the left and right front wheels 11L, 11R with a preset braking force in the left and right hydraulic brake devices 16L, 16R. Bring braking. At this time, the hydraulic brake devices 16L, 16R are connected to the front wheels 11L, 11R.
The braking force applied to the left and right front wheels 11 when the vehicle is traveling on a dry road surface, even when no load is loaded.
L and 11R are set to a size that can provide a braking force that does not significantly slip and that does not significantly increase the braking distance even when the load is fully loaded.

The controller 46 also determines the rear wheel speed N
When D1 (ND2) falls below the stop determination value ND0,
The power supply to the brake control valve unit 33 is stopped to stop the operation of the left and right hydraulic brake devices 16L and 16R, and the braking of the left and right front wheels 11L and 11R is released. The stop determination value ND0 is determined by the drive wheel 12 and the left and right front wheels 11L and 11L.
It is provided to suppress a shock generated in the vehicle body 14 when the vehicle braked by R stops, and
The value is set to a value corresponding to the vehicle speed at which the vehicle can be stopped smoothly without increasing the braking distance by braking only the drive wheels 12.

(Failure-time braking control) The controller 46
When at least one of the front wheel rotation speeds NLF and NRF cannot be detected and the slip of the drive wheel 12 cannot be detected, the hydraulic brake devices 16L and 16R are operated based on the fact that the accelerator lever 22 has been switched back, and the left and right wheels are operated. Failure-time braking control for controlling the brake control valve unit 33 so as to brake the front wheels 11L and 11R is performed.

As a braking control at the time of failure, the controller 46
When at least one of the front wheel rotation speeds NLF and NRF is no longer input, when the forward signal SF is switched to the reverse signal SR while the traveling motor 26 is in the normal rotation state, similar to the motor operation control described above. The target braking torque corresponding to the accelerator opening ACC and the motor speed NM1 (NM2) at that time is set using the map, and the traveling motor 26 is operated at the target braking torque. Also, when the reverse signal SR is switched to the forward signal SF while the traveling motor 26 remains in the reverse rotation, the traveling motor 26 is similarly operated at the set target braking torque.

The controller 46 supplies the drive current to the brake control valve unit 33 to operate the left and right hydraulic brake devices 16L and 16R, and the left and right front wheels 1
Brakes 1L and 11R.

Next, the running control including the above-described respective controls performed by the controller 46 will be described with reference to the running control flowcharts shown in FIGS. This traveling control is repeatedly executed at a predetermined control cycle.

In the traveling control, the controller 46
First, in step (hereinafter abbreviated as S) 10, it is determined whether or not both the front wheel rotation speeds NLF and NRF are input.
Next, in S20, a front wheel speed VLF (VRF) is obtained from the front wheel rotation speed NLF (NRF). At this time, the controller 46
Indicates that when the vehicle is turning, the front wheels 11 on the outside of the turn
L (11R) front wheel speed NLF (NRF) to front wheel speed V
Find LF (VRF).

Next, in S30, the rear wheel speed VD is obtained from the rear wheel speed ND1 (ND2), and in S40, the converted rear wheel speed VDP is obtained from the front wheel speed VLF (VRF) obtained in S10. Then, in S50, the slip speed ΔVD is obtained by subtracting the converted rear wheel speed VDP from the rear wheel speed VD.

Next, at S60, the motor rotation speeds NM1, NM2
From the phase shift relationship, whether the traveling motor 26 is in the normal rotation state and the reverse signal SR is being input, or whether the traveling motor 26 is in the reverse rotation state and It is determined whether or not the signal SF is being input.

If the condition of S60 is not satisfied, the program proceeds to S7
At 0, the target torque is set from the forward and reverse signals SF, SR, the accelerator opening ACC, and the motor speed NM1 (NM2). Then, in S80, the operation of the traveling motor 26 is controlled by the target torque (driving torque or braking torque).

On the other hand, if the above condition is satisfied in S60, the target braking torque is set in S90 from the forward and reverse signals SF and SR, the accelerator opening ACC and the motor speed NM1 (NM2). The operation of the motor 26 is controlled by the target braking torque.

Next, in S110, it is determined whether or not the slip speed ΔVD obtained in S50 is lower than the reference slip speed ΔVD0. If the slip speed ΔVD is lower than the reference slip speed ΔVD0 in S110, in S120,
The braking torque of the traveling motor 26 is limited so that the slip speed ΔVD converges in an appropriate range.

In S130 executed after S120, it is determined whether or not the rear wheel rotation speed ND1 (ND2) is lower than a stop determination value ND0. If the rear wheel rotation speed ND1 (ND2) is equal to or greater than the stop determination value ND0 in S130, the brake control valve unit 33 is operated in S140 and the left and right front wheels 1
This processing is terminated with the 1L and 11R braked.

On the other hand, at S130, the rear wheel speed ND1 (ND2)
Is less than the stop determination value ND0, the brake control valve unit 33 is deactivated in S150, and the left and right front wheels 11L and 11R are released from braking, and this processing is ended.

If it is determined in S10 that one of the front wheel rotation speeds NLF and NRF has not been input, the program proceeds to S160.
It is determined whether the traveling motor 26 is in the normal rotation state and the reverse signal SR is being input, or whether the traveling motor 26 is in the reverse rotation state and the forward signal SF is input. It is determined whether it is in the state to be performed.

If the condition of S160 is not satisfied,
At 170, the forward and reverse signals SF and SR, the accelerator opening A
A target torque is set based on the CC and the motor speed NM1 (NM2), and in S180, the operation of the traveling motor 26 is controlled with the target torque. Then, in S190, the present process ends with the hydraulic brake devices 16L and 16R released.

On the other hand, when the above condition is satisfied in S160, the target braking torque is set in S200 from the forward / reverse signals SF and SR, the accelerator opening ACC and the motor speed NM1 (NM2). The operation of the motor 26 is controlled by the target braking torque.

Next, at step S220, the brake control valve unit 33 is controlled to brake the left and right front wheels 11L and 11R, and this processing is terminated. Therefore, when the accelerator lever 22 is switched back while the vehicle is moving forward or backward, the driving wheels 12 are braked by the regenerative braking of the traveling motor 26. At this time, if the road surface is slippery or the regenerative braking force is large, the drive wheels 12 slip on the road surface. The driving wheel 12 slips and the slip speed Δ
When VD falls below the reference slip speed ΔVD0, the braking torque of the traveling motor 26 is limited, and the slip of the drive wheels 12 is suppressed. As a result, at the time of the switchback operation, the vehicle is braked by the drive wheels 12, and the slip is limited, so that the braking force against the road surface is secured.

At this time, once the slip speed ΔVD falls below the reference slip speed ΔVD0, the hydraulic brake device 1
6L and 16R are operated, and the left and right front wheels 11L and 11R are braked. For this reason, when braking by the drive wheel 12 alone is not enough, the vehicle is also braked by the left and right front wheels 11L and 11R.

Further, when the switchback operation is performed in a state where the left or right front wheel speed sensor 45L (45R) fails and the front wheel speed NLF (NRF) cannot be detected, the drive wheel 12 is braked by regenerative braking. At the same time, the hydraulic brake devices 16L and 16R operate to brake the left and right front wheels 11L and 11R. Therefore, when the front wheel rotation speed sensors 45L and 45R fail and the slip of the drive wheel 12 cannot be detected, the left and right front wheels 11L and 11R are braked regardless of the slip of the drive wheel 12.

The traveling motor 26 is an AC induction motor, and has an accelerator opening ACC and a motor rotation speed NM1 (NM M
The operation is controlled by controlling the current value and frequency of the three-phase alternating current based on 2). For this reason, when the motor speed sensors 42a and 42b fail, the traveling motor 26
Cannot be driven, and the vehicle cannot be driven.

According to the travel control device for a reach forklift described in detail above, the following effects can be obtained. (1) When the front wheel rotation speeds NLF and NRF cannot be detected, the hydraulic brake devices 16L and 16R are controlled based on the fact that the accelerator lever 22 has been switched back, and the left and right front wheels 11L and 11R are braked. Therefore, even if the slip of the drive wheel 12 cannot be detected due to the failure of the front wheel speed sensors 45L, 45R or the disconnection of the signal line thereof, the left and right front wheels 11L, 11R are braked at the time of the switchback operation regardless of the slip of the drive wheel 12. Is done. As a result, the braking distance does not increase against braking of the operator during braking.

(2) When the braked drive wheel 12 slips, the left and right front wheels 11L and 11R are braked by the hydraulic brake devices 16L and 16R. Therefore, the left and right front wheels 11 require less power consumption as compared to the case where the left and right front wheels are braked by reversely driving the auxiliary motor that is temporarily driven like a conventional reach forklift.
L, 11R can be braked.

(3) The running motor 26 is controlled so that the slip speed ΔVD obtained from the front wheel rotation speed NLF (NRF) and the rear wheel rotation speed ND converges to a predetermined allowable range.
The slip of the driving wheel 12 is limited. Therefore,
The braking distance can be made shorter, and the rear portion of the vehicle body 14 can hardly swing right and left.

Hereinafter, embodiments other than the above embodiment will be listed. In the above-described embodiment, in the configuration in which the traction control during braking (regenerative braking force control) for limiting the slip of the driving wheel 12 on the road surface is not performed when the driving wheel 12 is braked by the regenerative braking, the left and right front wheels 11 during the switchback operation.
It is good also as a structure which brakes L and 11R. Also in this case, it is possible to prevent the braking distance from becoming longer unintentionally during braking in a state where slippage of the drive wheel 12 cannot be detected.

In the above-described embodiment, when the driving wheel 12 slips when the driving motor 12 is driven by the braking torque and the driving wheel 12 is braked during the motor operation control, the driving is performed not only at the time of switchback but also at the time of driving. When the slip of the wheel 12 is detected, the left and right front wheels 11L and 11R are braked. When the slip of the drive wheel 12 is no longer detected due to a failure of the front wheel speed sensors 45L and 45R, the accelerator opening ACC and the motor speed NM1
The left and right front wheels 11L, 11R are braked based on the fact that (NM2) is in an area where the traveling motor 26 is driven by the braking torque. In this case, even if the slip of the drive wheels 12 cannot be detected, the braking distance is prevented from becoming undesirably long when the vehicle is braked by loosening the accelerator lever 22 to the neutral position side during power running. be able to.

In the above embodiment, when only one front wheel speed sensor 45L (45R) fails, the front wheel speed NRF (NLF) detected by the non-failed front wheel speed sensor 45R (45L) is determined. Drive wheel 1 during braking using
2, the braking force of the traveling motor 26 may be limited. In this configuration, even if only one of the front wheel speed sensors 45L (45R) fails, almost normal braking traction control can be performed.

In the above embodiment, the traveling motor 26 may be a DC motor. In this case, the motor operation can be controlled even if the motor rotation speeds NM1 and NM2 cannot be detected. Therefore, not only when the front wheel speed sensors 45L and 45R fail, but also when the motor speed sensors 42a and 42R
When the switch 2b breaks down, the drive wheels 12 can be braked at the time of the switchback operation, and the left and right front wheels 11L and 11R can also be braked.

In a configuration in which the traveling motor is a DC motor, the rotation deceleration due to the braking of the drive wheel 12 is detected from the rear wheel rotation speed ND1 (ND2). When the rotational deceleration exceeds a value that cannot be reached unless the drive wheels 12 slip, the hydraulic brake devices 16L and 16R are controlled to brake the left and right front wheels 11L and 11R. In this configuration, when the slip of the drive wheel 12 cannot be detected due to a failure of the motor speed sensors 42a, 42b or the like, the hydraulic brake devices 16L, 16R are operated based on the switch-back operation of the accelerator lever 22. You may.

In the above-described embodiment, the mechanical brake device for braking the drive wheel 12 by operating the brake pedal 24 as the brake operating means is provided, and the slip of the drive wheel 12 with respect to the road surface when braking is performed by the mechanical brake device. Is detected. Then, the left and right front wheels 11L, 11R are braked by operating the hydraulic brake devices 16L, 16R based on the detection result. In this case, when the slip of the drive wheel 12 cannot be detected, the hydraulic brake devices 16L and 16R are operated based on the operation of the brake pedal 24. Also in this configuration, even if the slip of the drive wheel 12 cannot be detected due to a sensor failure or the like, it is possible to prevent the braking distance from becoming long against the intention of the operator during braking.

In the above embodiment, the hydraulic brake device 1
Instead of 6L and 16R, the left and right front wheels 11 are controlled by electric control.
It is good also as an electric brake device which brakes L and 11R. Also in this case, the left and right front wheels 11 require less power consumption.
L, 11R can be braked.

The traveling control device of the reach forklift is not limited to a traveling control device of an industrial vehicle in which the front wheels are drive wheels and the rear wheels are driven wheels. Hereinafter, technical ideas grasped from each of the above-described embodiments will be described together with their effects.

(1) A reach-type forklift truck provided with the travel control device for an industrial vehicle according to any one of claims 1 to 6. (2) The travel control device for an industrial vehicle according to claim 1, wherein the braking control means controls an electric brake device to brake the driven wheels. This configuration also requires less power consumption than when braking is performed by driving the driven wheels in reverse by the auxiliary electric motor.

[0087]

According to the first to sixth aspects of the present invention, when braking in a state where it is no longer possible to detect slippage of the braked drive wheels with respect to the road surface, the braking distance is unexpectedly increased. It can be kept from becoming long.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a travel control device of a reach forklift.

FIG. 2 is a schematic side view of a reach forklift.

FIG. 3 is a schematic plan view similarly.

FIG. 4 is a flowchart of a traveling control process.

FIG. 5 is also a flowchart.

FIG. 6 is also a flowchart.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Reach type forklift truck as an industrial vehicle, 11L, 11R ... Front wheel as a driven wheel, 12 ... Driven steering wheel as a drive wheel, 16L, 16R ... Hydraulic brake device, 22 ... Accelerator lever as a brake operating means, 26 ... A traveling motor as an electric motor, 31... A hydraulic motor constituting braking control means, 32... An oil pump, 33.
2a, 42b: motor rotation speed sensors constituting braking control means and driving wheel revolution number detecting means; 45L, 45R ... front wheel revolution number sensors constituting braking control means and driven wheel revolution number detecting means; 46, braking control means; Controllers ND1 and ND2 as braking force control means constituting driven wheel rotation speed detection means, drive wheel rotation speed detection means and slip detection means
... Rear wheel speed as drive wheel speed, NLF, NRF. Front wheel speed as driven wheel speed, ND .Rear wheel speed as drive wheel speed.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B60K 41/20 B60K 41/20 B60L 15/20 B60L 15/20 Y G01P 3/56 G01P 3/56 A F term (reference) 3D037 EB03 EC07 FA14 3D041 AA65 AA71 AB07 AC01 AC26 AD00 AD02 AD10 AD51 AE02 AE41 5H115 PA08 PC06 PG05 PI16 PI29 PO06 PO17 PU09 PV09 QE10 QH08 QI02 QI04 QI07 QI12 QI14 QN03 RB15 SE03 TB01 TO03 TB03 TO03 TB03 TO03 TB03 TO03

Claims (6)

[Claims] 1. An industrial vehicle comprising: a brake control means for detecting a slip of a drive wheel braked on a road surface based on an operation of a brake operation means operated by an operator and braking a driven wheel based on a result of the detection. In the travel control device, a travel control device for an industrial vehicle that brakes the driven wheel based on an operation of the brake operation device when the brake control unit cannot detect slippage of the drive wheel on a road surface. 2. The travel control device for an industrial vehicle according to claim 1, wherein the braking control means controls a hydraulic brake device to brake the driven wheels. 3. The travel control device for an industrial vehicle according to claim 1, wherein the brake operation means is an accelerator lever for controlling operation of an electric motor that regeneratively brakes the drive wheels, The travel control device for an industrial vehicle that brakes the driven wheel based on a switchback operation of the accelerator lever. 4. The travel control device for an industrial vehicle according to claim 3, wherein a slip of the drive wheels on a road surface due to regenerative braking of the electric motor is detected, and the regenerative braking of the electric motor is limited so as to limit the slip. A travel control device for an industrial vehicle, comprising: a braking force control unit that controls a braking force by the vehicle. 5. The travel control device for an industrial vehicle according to claim 1, wherein the brake operation means is a brake pedal that operates a mechanical brake device for braking the drive wheels. The travel control device for an industrial vehicle that brakes the driven wheel based on the operation of the brake pedal. 6. The traveling control device for an industrial vehicle according to claim 1, wherein the braking control unit includes a driven wheel rotation speed detection unit that detects a rotation speed of the driven wheel. A drive wheel rotation number detection unit that detects a rotation number of the drive wheel; and a slip detection unit that detects slip of the drive wheel with respect to a road surface from the rotation number of the driven wheel and the rotation number of the drive wheel. Industrial vehicle travel control device.