JP3422314B2 - Travel control device for industrial vehicles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for an industrial vehicle such as a reach type forklift truck, which brakes driven wheels when the braked drive 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) has a steering wheel (hereinafter, referred to as a drive wheel) driven by an electric motor driven by a battery.
It runs by simply driving the drive wheels. Also,
In a reach forklift, the vehicle is braked by braking the drive wheels. Braking of the driving wheels is performed mainly by regenerative braking of an electric motor controlled based on a switchback operation of an accelerator lever.

If the drive wheels are braked by regenerative braking while the vehicle is traveling on a slippery road surface, the drive wheels may slip on the road surface. As a result, the braking distance may become long and the rear part of the vehicle body may be swung to the left or right.

A reach forklift for solving such a problem is proposed in JP-A-11-122721. 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 by auxiliary motors (electric motors) provided respectively. For this reason, when braking only the drive wheels, when the drive wheels slip, the vehicle is also braked by the left and right front wheels, which makes it difficult for the braking distance to be long and the rear portion of the vehicle body to be swung left and right.

[0005]

In the above reach forklift, the assist is performed based on the result of comparison between the front wheel speed signal obtained by detecting the rotational speeds of the left and right front wheels and the rear wheel speed command signal which becomes "0" during braking. Drive the motor in reverse. Therefore, tachometers for detecting the rotational 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 will not be braked even if the drive 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 undesirably increase.

This not only applies to the case where the drive wheels are braked by the regenerative braking of the electric motor, but also the drive wheels are braked by the mechanical brakes operated by the operation of the brake pedal, and when the drive wheels slip, the left and right front wheels are moved. This is a problem that occurs even if braking is applied.

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

The present invention has been made to solve the above problems, and an object of the present invention is to perform braking at the time of braking in a state in which the slip of the driving wheels on the road surface due to braking cannot be detected. It is an object of the present invention to provide a traveling control device for an industrial vehicle that can prevent the distance from unintentionally increasing.

[0010]

In order to solve the above problems, the invention according to claim 1 detects a slip of a drive wheel braked on the road surface based on an operation of a brake operating means operated by an operator. In the traveling control device for an industrial vehicle, which comprises a braking control means for braking the driven wheels based on the detection result, the braking control means, when the slip of the drive wheels with respect to the road surface cannot be detected,
The brake operating means for braking the driven wheel and is operated.

According to the first aspect of the present invention, when the drive wheels are braked based on the operation of the brake operating means, the driven wheels are braked when the drive wheels slip on the road surface. Further, when the slip of the drive wheels cannot be detected, the drive wheels are braked and the driven wheels are braked when the brake operating means is operated. Therefore, when the slip of the drive wheel due to braking cannot be detected, the driven wheel is braked regardless of the slip of the drive wheel.

A second aspect of the present invention is based on the first aspect, wherein 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 wheels are braked by being driven in reverse by the auxiliary electric motor.

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

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

According to a fourth aspect of the present invention, in the operation of the third aspect of the invention, in the traveling control device for an industrial vehicle according to the third aspect, the drive surface of the drive wheel is regenerated by the regenerative braking of the electric motor. The gist of the present invention is to provide a braking force control means for detecting a slip and controlling the braking force by the regenerative braking of the electric motor so as to limit the slip.

According to the invention of claim 4, claim 3
In addition to the effect of the invention described in (1), when the drive wheel is braked by the regenerative braking of the electric motor, the braking force of the electric motor is controlled so that the slip of the drive wheel is limited. Therefore, since the drive wheels do not unnecessarily slip on the road surface during braking, it is possible to further shorten the braking distance and further stabilize the posture of the vehicle body.

The invention according to claim 5 is the invention according to claim 1 or 2, in the traveling control device for an industrial vehicle according to claim 1 or 2, wherein the brake operating means is A brake pedal for activating a mechanical brake device for braking a drive wheel, wherein the braking control means brakes the driven wheel when the brake pedal is operated.

According to the invention of claim 5, claim 1
Alternatively, in addition to the effect 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 when the vehicle is braked by operating the brake pedal, it is possible to prevent the braking distance from unintentionally increasing.

The invention described in claim 6 is the same as the invention described in any one of claims 1 to 5,
The traveling control device for an industrial vehicle according to claim 5, wherein the braking control means detects a driven wheel rotation speed detection means for detecting a rotation speed of the driven wheel and a rotation speed of the drive wheel. The gist of the present invention is to include a drive wheel rotation speed detection means for performing the above, and a slip detection means for detecting a slip of the drive wheel with respect to the road surface from the rotation speed of the driven wheel and the rotation speed of the drive wheel.

According to the invention of claim 6, claim 1
In addition to the operation of the invention described in any one of claims 5 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. Even if the slip of the drive wheel cannot be detected due to a failure of either the driven wheel rotation speed detection means or the drive wheel rotation speed detection means or the disconnection of the signal line thereof, etc., regardless of the slip of the drive wheel during the brake operation. The driven wheels as well as the driven wheels are braked.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION 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 includes a pair of left and right driven wheels as front wheels 11L and 11R, and drive wheels as drive wheels. The vehicle body 14 is provided with (hereinafter, simply referred to as drive wheels) 12 and rear wheels including casters 13.

The front portion of the vehicle body 14 is composed of a pair of left and right reach legs 15L and 15R. Each reach leg 15
L and 15R respectively support the front wheels 11L and 11R at their tips. Hydraulic brake devices 16L and 16R are provided on the front wheels 11L and 11R, respectively. A mast device 17 is supported between the reach legs 15L and 15R so as to be reachable in the front-rear direction. 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 on the front side of the driver's seat 19, and a steering wheel 21 is provided on the left side of the driver's seat 19. The handle 21 is provided to steer the drive wheels 12. The operation panel 20 includes an accelerator lever 22 as a brake operating means and a plurality of cargo handling levers 23.
And are provided. A brake pedal 24 for braking the drive wheels 12 is provided on the floor of the driver's seat 19.
Is provided.

On the left side of the rear portion of the vehicle body 14, the drive wheels 12 are provided.
A drive unit 25 for driving the motor is provided. The drive unit 25 includes a traveling motor 26 as an electric motor and a wheel supporting portion 27.
The drive wheel 12 supported by the driving motor 26 is 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, the hydraulic device that constitutes the travel control device of the reach truck will be described. As shown in FIG. 1, the hydraulic system includes an oil tank 30 and a hydraulic motor 3.
1, an oil pump 32, a brake control valve unit 33, and the like.

The hydraulic motor 31 drives the oil pump 32 to supply the hydraulic oil in the oil tank 30 to the brake control valve unit 33 and the oil control valve unit 34 at a predetermined hydraulic pressure. The oil control valve unit 34 is an integrated valve that is operated by each cargo handling lever 23, 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 a unit in which a pressure reducing valve, a shutoff valve, a linear solenoid valve, an accumulator 33a and the like (not shown) are integrated. The brake control valve unit 33 stores hydraulic oil supplied from the oil pump 32 at a predetermined hydraulic pressure in the accumulator 33a and controls the hydraulic pressure output to the hydraulic brake devices 16L and 16R by electrical control. Each hydraulic brake device 16L, 16R brakes the front wheels 11L, 11R with a braking force according to the hydraulic pressure of the supplied hydraulic oil.

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

In this embodiment, the controller 46 is braking force control means and slip detection means. Further, the motor rotation speed sensors 42a and 42b and the controller 46 constitute drive wheel rotation speed detection means, and the front wheel rotation speed sensor 45
L, 45R and the controller 46 constitute a driven wheel rotation speed detecting means. Further, the hydraulic motor 31, the oil pump 3
2, brake control valve unit 33, motor rotation speed sensors 42a, 42b, front wheel rotation speed sensors 45L, 45R
And the controller 46 constitutes 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 rotation 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.

The accelerator opening sensor 40 is arranged below the operation panel 20 and detects the accelerator opening ACC of the accelerator lever 22 operated from the neutral position to the forward side or the reverse side,
The detection signal is output to the controller 46.

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

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. Each of the motor rotation speed sensors 42a, 42b has a motor rotation speed NM1, NM2 (where NM1 = N) which is the rotation speed of the output shaft of the traveling motor 26.
M2), that is, the rear wheel rotational speed ND that is the rotational speed of the drive wheel 12
Pulse signals corresponding to 1 and ND2 (however, ND1 = ND2) are generated and output to the controller 46, respectively. The motor rotation speed sensors 42a and 42b are provided so that the respective pulse signals are output at the timings in which the phases are deviated by 90 °, and the phase deviation relationship is reversed according to the rotation direction of the traveling motor 26. Has been.

The steering angle sensor 43 is the drive unit 25.
A steering angle θ of the drive wheel 12 that is steered rightward or leftward is detected from a straight traveling state by using a gear (not shown) that rotates together with the detected body as a detected body, and outputs the detection signal 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 hydraulic pressure of the accumulator 33a falls below a predetermined hydraulic pressure.

The front wheel rotation speed sensors 45L and 45R are provided on the reach legs 15L and 15R, and detect the detected portions provided on the front wheels 11L and 11R, respectively. And
The front wheel rotation speed sensor 45L controls 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 outputs 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) including a microcomputer, a three-phase inverter circuit, a solenoid valve drive circuit, and the like. The controller 46 causes the traveling motor 26, by causing the microcomputer to execute various control programs stored in advance.
The hydraulic motor 31 and the brake control valve unit 33 are controlled. 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, the brake control valve unit 33 is supplied with a drive current corresponding to the target braking force of the hydraulic brake devices 16L and 16R.

The traveling motor 26 is normally or reversely rotated by 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 rotates by the drive current supplied from the controller 46.

The brake control valve unit 33 supplies hydraulic pressure corresponding to the drive current supplied from the controller 46 to the hydraulic brake devices 16L and 16R. The controller 46 operates the hydraulic motor 31 when each cargo handling lever 23 is operated, and when the detection signal is input from the pressure switch 44 even when each cargo handling lever 23 is not operated, the controller 46 drives the hydraulic motor 31. drive.
In addition, the controller 46 controls the motor rotation speed sensors 42.
From the phase shift relationship of both pulse signals input from a and 42b, it is determined whether the rotation direction of the traveling motor 26 is forward rotation or reverse rotation, that is, whether the drive wheel 12 is forward rotation or reverse rotation. Determine if there is.

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

(Motor operation control) The controller 46
Motor operation control for controlling the traveling motor 26 is performed based on the accelerator opening degree 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 operated to the forward drive side or the reverse drive side based on the forward drive and reverse drive signals SF and SR. Further, it is determined from the motor rotational speeds NM1 and NM2 whether the rotational direction of the traveling motor 26 at that time is forward rotation or reverse rotation. And accelerator lever 2
Depending on the side on which 2 is operated, the rotation direction and the target torque are set from the accelerator opening ACC and the motor rotation speed NM1 (= NM2) at that time, and the traveling motor 26 is operated at the target torque. The controller 46 controls the forward and reverse signals SF and SR, the accelerator opening ACC and the motor speed N.
The target torque is set using the map in which the target torque is set corresponding to M1 (NM2).

More specifically, the controller 46, as the motor operation control, receives the forward drive signal SF and the rotation direction of the traveling motor 26 is forward rotation, and 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 drive signal SR is input and the rotation direction of the traveling motor 26 is reverse.

Further, for motor operation control, the controller 46 receives the reverse signal SR while the rotation direction of the traveling motor 26 remains forward, or the forward signal SF while the rotation direction remains reverse. At this time, that is, 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
A 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 according to the operation direction of the accelerator lever 22, the accelerator opening ACC and the vehicle speed to drive 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 reverse side or the forward side is used. The drive wheels 12 are braked to brake the vehicle.

(Regenerative braking force control) Also, the controller 4
Reference numeral 6 denotes 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 wheel 12 is detected based on D1 and ND2, and regenerative braking force control (braking traction control) for limiting the braking torque of the traveling motor 26 is performed.

As the regenerative braking force control, the controller 46
The front wheels 11L and 11R from the front wheel rotation speeds NLF and NRF using the previously stored radii of the front wheels 11L and 11R.
The front wheel speeds VLF and VRF, which are the moving speeds of, are obtained. At this time, the controller 46 obtains either the left or right front wheel speed VLF (or VRF) when the vehicle is in a straight traveling state,
When the vehicle is turning, the front wheels 1 on the outside of the turn are
The front wheel speed VLF (or VRF) of 1L (or 11R) is obtained. This is either the left or right front wheel 11L (or 11R)
Front wheel speed VLF (or VR
This is for detecting F).

Further, the controller 46 controls the rear wheel rotation speed N
From D1 (ND2), the rear wheel speed VD is calculated using the radius of the drive wheel 12 stored in advance. This rear wheel speed VD is
When there is a slip between the drive wheel 12 and the road surface, the moving speed of the drive wheel 12 becomes smaller than the moving speed by the slip amount.

Next, the controller 46 calculates the front wheel speed VLF (or VRF) from the ratio of the turning radius of the front wheels 11L (11R) and the turning radius of the drive wheels 12 according to the steering angle θ at that time. The front wheel speed VLF is multiplied by the determined correction coefficient.
The converted rear wheel speed VDP is calculated by converting (or VRF) into the moving speed of the drive wheel 12.

Then, the controller 46 subtracts the converted rear wheel speed VDP from the rear wheel speed VD to obtain a speed difference (VD
-VDP) is a slip velocity ΔVD (= (VD-VDP) <0) for detecting a slip of the driving wheel 12 on the road surface.
Ask as. That is, the sliding speed ΔVD is the driving wheel 12
Of the driving wheel 1 exceeds the maximum braking force determined by the weight of the driving wheel and the friction coefficient between the driving wheel 1 and the road surface.
2 is a speed difference corresponding to the fact that 2 is slipped on the road surface and is smaller than the moving speed of the drive wheels 12.

As a regenerative braking force control, the controller 46 drives the drive wheel 1 when the slip velocity ΔVD falls below a preset reference slip velocity ΔVD0 (<0).
It is determined that No. 2 is slipping on the road surface, and the braking torque of the traveling motor 26 is limited so that the slip velocity ΔVD becomes a value within a preset appropriate range.

Driving force control (traction control during power running) for limiting the target drive torque of the traveling motor 26 when slip of the drive wheels 12 is detected even during power running of the vehicle.
Is done.

(Front Wheel Braking Control) Further, the controller 4
6 controls the brake control valve unit 33 to control the left and right hydraulic brake devices 16 during the regenerative braking force control.
L and 16R are operated to perform front wheel braking control for braking the left and right front wheels 11L and 11R.

As the front wheel braking control, the controller 46
When the front wheel rotation speed NLF (NRF) is equal to or greater than the preset stop determination value ND0, the slip speed ΔV is
Once D falls below the reference slip velocity 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 the left and right front wheels 11L and 11R are driven by the preset braking force of the left and right hydraulic brake devices 16L and 16R. Brake. At this time, the hydraulic brake devices 16L and 16R are connected to the front wheels 11L and 11R.
The braking force applied to the left and right front wheels 11 even when no load is loaded when the vehicle is traveling on a dry road surface.
L and 11R are set to a size within a range in which a large braking force can be obtained without causing a significant slippage, and even when the load is fully loaded.

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

(Failure 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 wheels 12 cannot be detected, the hydraulic brake devices 16L and 16R are operated based on the switchback operation of the accelerator lever 22. Braking control at the time of failure is performed to control the brake control valve unit 33 so as to brake the front wheels 11L and 11R.

As a braking control at the time of failure, the controller 46
When at least one of the front wheel rotational speeds NLF and NRF is not input, when the forward drive signal SF is switched to the reverse drive signal SR while the traveling motor 26 is in the normal rotation state, the same as in the motor operation control described above. A target braking torque corresponding to the accelerator opening ACC and the motor rotation speed NM1 (NM2) at that time is set using the map, and the traveling motor 26 is operated at the target braking torque. Further, when the reverse drive signal SR is switched to the forward drive signal SF while the traveling motor 26 is still in reverse rotation, the traveling motor 26 is similarly driven with the set target braking torque.

Further, 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
Braking 1L and 11R.

Next, the traveling control including the above-mentioned controls performed by the controller 46 will be described with reference to the traveling control flowcharts shown in FIGS. This traveling control is repeatedly executed every 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, the front wheel speed VLF (VRF) is obtained from the front wheel rotation speed NLF (NRF). At this time, the controller 46
When the vehicle is turning, the front wheels 11 on the outside of the turn are
Front wheel speed V from L (11R) front wheel speed NLF (NRF)
Calculate 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, in S60, the motor speeds NM1 and NM2
The traveling motor 26 is in the forward rotation state and is in the state in which the reverse drive signal SR is input, or the traveling motor 26 is in the reverse rotation state and is in the forward drive state. It is determined whether or not the signal SF is input.

When the condition of S60 is not satisfied, 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 traveling motor 26 is operation-controlled with the target torque (driving torque or braking torque).

On the other hand, when the above condition is satisfied in S60, the target braking torque is set from the forward and reverse signals SF, SR, the accelerator opening ACC and the motor rotation speed NM1 (NM2) in S90, and the vehicle travels in S100. The operation of the motor 26 is controlled by the target braking torque.

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

In S130 executed after S120, it is determined whether or not the rear wheel rotation speed ND1 (ND2) is below the stop determination value ND0. When the rear wheel rotation speed ND1 (ND2) is equal to or higher than the stop determination value ND0 in S130, the brake control valve unit 33 is operated in S140 to operate the left and right front wheels 1.
This processing is terminated by setting the braking of 1L and 11R.

On the other hand, in S130, the rear wheel rotation speed ND1 (ND2)
Is below the stop determination value ND0, the brake control valve unit 33 is stopped in S150, and the left and right front wheels 11L and 11R are de-braked, and this processing ends.

Further, if either one of the front wheel rotation speeds NLF and NRF is not input in S10, S160
Then, whether or not the traveling motor 26 is in the normal rotation state and the reverse signal SR is input, or whether the traveling motor 26 is in the reverse rotation state and the forward signal SF is input. It is determined whether or not it is in the state.

When the condition of S160 is not satisfied, S
At 170, forward and reverse signals SF and SR, accelerator opening A
A target torque is set from the CC and the motor rotation speed NM1 (NM2), and the traveling motor 26 is operation-controlled at the target torque in S180. Then, in step S190, the hydraulic brake devices 16L and 16R are released, and this processing ends.

On the other hand, when the above condition is satisfied in S160, the target braking torque is set from the forward and reverse signals SF and SR, the accelerator opening ACC and the motor speed NM1 (NM2) in S200, and the target braking torque is set in S210. The operation of the motor 26 is controlled by the target braking torque.

Next, in S220, the brake control valve unit 33 is controlled to set the state in which the left and right front wheels 11L and 11R are braked, and this processing ends. Therefore, when the accelerator lever 22 is switched back while the vehicle is moving forward or backward, the drive 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 slip velocity 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, when the switchback operation is performed, the vehicle is braked by the drive wheels 12, and the slip is limited to secure the braking force on the road surface.

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

Further, when the switchback operation is performed in a state where either the left or right front wheel rotation speed sensor 45L (45R) fails and the front wheel rotation speed NLF (NRF) cannot be detected, the drive wheels 12 are braked by regenerative braking. At the same time, the hydraulic brake devices 16L and 16R are activated 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 the accelerator opening ACC and the motor speed NM1 (NM
Operation is controlled by controlling the current value and frequency of the three-phase AC based on 2). Therefore, when the motor rotation 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 the reach forklift described above in detail, 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 switchback operation of the accelerator lever 22 to brake the left and right front wheels 11L and 11R. Therefore, even if the slip of the drive wheel 12 cannot be detected due to a failure of the front wheel rotation speed sensors 45L and 45R or disconnection of the signal line thereof, the left and right front wheels 11L and 11R are braked during the switchback operation regardless of the slip of the drive wheel 12. To be done. As a result, the braking distance does not increase against the operator's will during braking.

(2) When the braked drive wheels 12 slip, the left and right front wheels 11L, 11R are braked by the hydraulic brake devices 16L, 16R. Therefore, the left and right front wheels 11 consume less power as compared with 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 and 11R can be braked.

(3) The traveling motor 26 is operated and controlled so that the slip velocity ΔVD obtained from the front wheel rotational speed NLF (NRF) and the rear wheel rotational speed ND converges within a predetermined allowable range.
The slip of the drive wheel 12 is limited. Therefore,
The braking distance can be further shortened, and the rear portion of the vehicle body 14 can be prevented from swinging right and left.

Embodiments other than the above embodiment will be listed below. In the above-described embodiment, when the driving wheels 12 are braked by the regenerative braking, the traction control during braking (regenerative braking force control) for limiting the slip of the driving wheels 12 on the road surface is not performed, and the left and right front wheels 11 are operated during the switchback operation.
A configuration may be adopted in which L and 11R are braked. In this case as well, it is possible to prevent the braking distance from unintentionally increasing during braking in the state where the slip of the drive wheels 12 cannot be detected.

In the above embodiment, when the drive wheel 12 slips when the traveling motor 26 is driven by the braking torque and the drive wheel 12 is braked during the motor operation control, the drive is performed not only during the switchback. When the slip of the wheel 12 is detected, the left and right front wheels 11L and 11R are braked. Then, when the slip of the drive wheels 12 is no longer detected due to a failure of the front wheel rotation speed sensors 45L, 45R or the like, the accelerator opening ACC and the motor rotation speed NM1 are detected.
The configuration is such that the left and right front wheels 11L and 11R are braked based on the fact that (NM2) is in the region where the traveling motor 26 is driven with the braking torque. In this case, even if the slip of the drive wheels 12 cannot be detected, the braking distance is prevented from unintentionally lengthening 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 of the front wheel rotation speed sensors 45L (45R) fails, the front wheel rotation speed NRF (NLF) detected by the front wheel rotation speed sensor 45R (45L) which is not in failure is detected. Drive wheel 1 when braking using
The slip of 2 may be detected and the braking force of the traveling motor 26 may be limited. With this configuration, even when only one of the front wheel rotation speed sensors 45L (45R) fails, the normal traction control during braking can be performed.

In the above embodiment, the traveling motor 26 may be a DC motor. In this case, the motor operation control can be performed even if the motor speeds NM1 and NM2 cannot be detected. Therefore, not only when the front wheel rotation speed sensors 45L and 45R malfunction, but also when the motor rotation speed sensors 42a and 4R
Even when 2b fails, the drive wheels 12 can be braked and the left and right front wheels 11L and 11R can be braked during the switchback operation.

In the 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 wheels 12 cannot be detected due to a failure of the motor rotation speed sensors 42a and 42b, the hydraulic brake devices 16L and 16R are operated based on the switchback operation of the accelerator lever 22. May be.

In the above embodiment, a mechanical brake device for braking the drive wheel 12 by operating the brake pedal 24 as a brake operating means is provided, and the drive wheel 12 slips on the road surface when braking by the mechanical brake device. To detect. Then, based on the detection result, the hydraulic brake devices 16L, 16R are operated to brake the left and right front wheels 11L, 11R. In this case, when the slip of the drive wheels 12 cannot be detected, the hydraulic brake devices 16L and 16R are operated based on the operation of the brake pedal 24. Even in the case of this configuration, even if the slip of the drive wheels 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 electrically controlled.
An electric brake device for braking L and 11R may be used. Also in this case, the left and right front wheels 11 consume less power.
L and 11R can be braked.

Not limited to the travel control device for the reach forklift, the travel control device may be, for example, an industrial vehicle in which the front wheels are the driving wheels and the rear wheels are the driven wheels. Hereinafter, the technical idea understood from each of the above-described embodiments will be described together with the effects thereof.

(1) A reach-type forklift truck equipped 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. Also with this configuration, power consumption can be reduced as compared with the case where the driven wheels are braked by being driven in reverse by the auxiliary electric motor.

[0087]

According to the first to sixth aspects of the present invention, the braking distance is unintentionally increased during braking in a state where the slip of the braked drive wheel with respect to the road surface cannot be detected. You can prevent it from becoming long.

[Brief description of drawings]

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

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

FIG. 3 is a schematic plan view of the same.

FIG. 4 is a flowchart of travel control processing.

FIG. 5 is also a flowchart.

FIG. 6 is also a flowchart.

[Explanation of symbols]

10 ... Reach type forklift truck as industrial vehicle, 11L, 11R ... Front wheel as driven wheel, 12 ... Drive steered wheel as drive wheel, 16L, 16R ... Hydraulic brake device, 22 ... Accelerator lever as brake operating means, 26 ... a traveling motor as an electric motor, 31 ... a hydraulic motor constituting a braking control means, 32 ... similarly an oil pump, 33 ... similarly a brake control valve unit, 4
2a, 42b ... Motor rotation speed sensor constituting braking control means and drive wheel rotation speed detecting means, 45L, 45R ... Front wheel rotation speed sensor constituting braking control means and driven wheel rotation speed 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 rotation speed as drive wheel rotation speed, NLF, NRF ... front wheel rotation speed as driven wheel rotation speed, ND ... rear wheel rotation speed as drive wheel rotation speed.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60K 26/02 B60K 28/16 B60L 15/00-15/38 B60L 7/00-7/28

Claims (6)

(57) [Claims] 1. An industrial vehicle having braking control means for detecting a slip of a drive wheel braked on the road surface based on an operation of a brake operating means operated by an operator and braking the driven wheel based on the detection result. the traveling control device, the brake control means, when it can not detect slip relative to the road surface of the driving wheels, the travel control device of the industrial vehicle for braking the driven wheel and the brake operation means is operated. 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 or 2, wherein the brake operating means is an accelerator lever for controlling the operation of an electric motor that regeneratively brakes the drive wheels, The braking control means is a traveling control device for an industrial vehicle, which brakes the driven wheels based on a switchback operation of the accelerator lever. 4. The traveling control device for an industrial vehicle according to claim 3, wherein a slip of the drive wheel with respect to 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 traveling control device for an industrial vehicle, comprising a braking force control means for controlling the braking force by the vehicle. 5. The travel control device for an industrial vehicle according to claim 1, wherein the brake operating means is a brake pedal that operates a mechanical brake device for braking the drive wheels, The braking control means is a travel control device for an industrial vehicle that brakes the driven wheels based on an operation of the brake pedal. 6. The traveling control device for an industrial vehicle according to claim 1, wherein the braking control means includes a driven wheel rotation speed detection means that detects a rotation speed of the driven wheel. A driving wheel rotational speed detecting means for detecting the rotational speed of the driving wheel, and a slip detecting means for detecting a slip of the driven wheel from the rotational speed of the driven wheel and the driving wheel. Running control system for industrial vehicles.