JP3226080B2 - Drive control device for reach type forklift - 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 a reach type forklift.

[0002]

2. Description of the Related Art A conventional forklift for controlling the driving of both front and rear wheels in order to prevent slipping when starting on a slippery road is disclosed in Japanese Patent Laid-Open No. Hei 5-162959. It is proposed as shown below.

In this reach-type forklift, a front-wheel motor is driven and controlled by chopper-controlling a control circuit having a front-wheel chopper circuit corresponding to a pair of front-wheel motors. Further, by controlling the control circuit having the rear wheel chopper circuit by chopper control, the rear wheel motor is driven and controlled, and the rear wheel also serving as steering is rotated.

Accordingly, when the accelerator lever is operated, the drive control circuit performs chopper control of the front wheel and rear wheel control circuits based on the operation amount, and drives the reach type forklift by constantly rotating the front wheel and the rear wheel. It is like.

As a result, when the vehicle starts on a slippery road surface, slip can be prevented and the vehicle can be started smoothly. However, the first prior art has a first problem as described below.

That is, in the above-mentioned reach type forklift, the front wheel and rear wheel motors are always driven and controlled, so that the front wheel is less worn than the reach type forklift where only the rear wheel motor is drive controlled. Is faster, leading to an increase in running costs. In addition, the power consumption of the battery mounted on the vehicle is increased by driving the front wheel motor, and the operating time is reduced.

Therefore, as means for solving the above problems, for example, Japanese Patent Application No. 5-308, which is a second prior art.
No. 378. That is, when the reach type forklift starts, both the front wheel and rear wheel motors are rotated and driven, and after traveling, only the rear wheel motor is rotated and driven, and the front wheel motor is not driven.
The front wheel is the driven wheel. Therefore, according to the second related art, it is possible to reduce front wheel wear and battery power consumption as compared with the first related art.

On the other hand, in the first prior art, in addition to the above-described first problem, there is further a second problem as described below. That is, in the first prior art, the front wheel motor and the rear wheel motor are each chopper-controlled by a control circuit including separate chopper circuits, so that the circuit configuration and control contents are complicated, and cost increases, reliability, and maintainability are improved. Leads to a decrease in

Further, depending on the type of the reach-type forklift, the two left and right front wheel motors may be independently chopper-controlled by separate control circuits, in which case the above-mentioned problem becomes more remarkable. .

As means for solving the above-mentioned second problem, for example, Japanese Patent Application No. Hei.
There is a method described in US Pat. That is, the three motors are connected in parallel to the DC power supply, and the three driving motors are simultaneously chopper-controlled by a control circuit including a single chopper circuit connected in series to the parallel circuit. Therefore, the circuit configuration and control contents of the control circuit are simplified, and the second problem described above can be solved.

Thus, as is apparent from the above description, according to the fourth prior art which simultaneously employs the second prior art and the third prior art, the first problem and the second problem occur. It is possible to solve points at the same time.

[0012]

However, the fourth prior art described in the preceding section still has the following problems.

That is, in the fourth prior art, as described in the second prior art, in the reach type forklift, all of the rear wheels and the front wheels are always driven at the time of start, regardless of the occurrence of slip. . By the way, a forklift frequently repeats stopping and starting due to its use environment, and thus the starting time accounts for a large proportion of the entire operating time. Therefore, the reduction in the operating time due to the wear of the front wheels and the increase in power consumption is still insufficient, even though it is improved over the first conventional technique.

In the fourth prior art, as described in the third prior art, a total of three drive motors, two front wheels and one rear wheel, are connected in parallel to a DC current, and one drive motor is connected. Since drive control is performed by the control circuit, control of each drive motor cannot be performed individually. By the way, the two front wheel drive motors are motors having smaller rated outputs than the rear wheel motors because of the auxiliary drive motors and restrictions on the installation space of the provided legs. As a result, the current that can be passed through the front wheel motor is smaller than the current that can be passed through the rear wheel motor, so that the current that can be passed as a whole is regulated by the front wheel motor. Therefore, when the vehicle starts to drive both the front wheels and the rear wheels, the driving force is reduced as compared to when the vehicle is running after the vehicle is driven after only the rear wheels are driven. As a result, starting on an uphill road,
A situation occurs in which the pushing operation at the time of starting becomes impossible due to insufficient driving force.

As described above, in the reach type forklift according to the fourth prior art, all the rear wheels and the front wheels are always driven at the time of start, regardless of the occurrence of slip. Therefore, if the road surface condition is a frozen low μ road surface on which slippage is likely to occur, the above situation does not cause any problem, but when starting on a high μ road surface where slippage cannot occur. The occurrence of the above-mentioned situation causes a great hindrance in cargo handling work.

The present invention solves the above-mentioned problems, and reliably prevents slippage of a reach-type forklift at the time of starting, and at the same time, prevents early wear of a front wheel and a decrease in operating time. And high μ at the start
It is an object of the present invention to provide a low-cost, high-performance reach-type forklift drive control device that prevents a decrease in driving force on a road surface and facilitates starting operation on an uphill road and pushing operation when starting. I do.

[0017]

According to a first aspect of the present invention, there is provided a drive control device for a reach-type forklift, comprising: legs provided on both left and right sides in front of the vehicle;
A front wheel provided on said leg, front-wheel electric driving the front wheels
A dynamic motor (hereinafter simply referred to as “front wheel motor”) , a rear wheel provided at a lower portion of the vehicle, and a rear wheel for driving the rear wheel.
Means for opening and closing an energy supply path for operating the front wheel motor in a drive control device of a reach type forklift including an electric motor (hereinafter simply referred to as "rear wheel motor") and a steering device for steering the rear wheel. Means for detecting the speed of the vehicle, means for determining whether or not the vehicle is starting based on the speed detected by the means for detecting the speed of the vehicle, and means for detecting slip of the vehicle. Opening and closing the energy supply path for operating the front wheel motor when the means for determining whether the vehicle is starting is determined to be at the start and when the means for detecting vehicle slip is determined to be the slip. Means for opening the energy supply path and driving the front wheels, while otherwise opening and closing the energy supply path. A processing means for disabling the driving of the front wheels; a means for determining whether or not the vehicle is starting; and a means for determining whether or not the vehicle is starting. Processing means for stopping supply of energy for operating the motor, holding the state for a predetermined period of time, and then starting supply of energy for operating the front-wheel motor and the rear-wheel motor; The predetermined time is set as a delay time from when the opening signal reaches the means for opening and closing the energy supply path for operating the front wheel motor to when the opening is actually performed.

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

In the drive control device for a reach type forklift according to the second aspect, the drive control device is provided on both left and right sides in front of the vehicle.
Drive leg, front wheel provided on the leg, and the front wheel
Front wheel motor and rear wheel provided at the lower part of the vehicle
And a rear wheel motor for driving the rear wheel; and steering the rear wheel.
Control system for reach-type forklift
In the control device, the front wheel motor and the rear wheel motor are:
Electric motor, energy to operate both motors
Is electric energy and operates the front wheel motor
Means for opening and closing the energy supply path, and the speed of the vehicle
And means for detecting the speed of the vehicle.
Determine whether the vehicle is starting or not based on the issued speed
Means, means for detecting slip of the vehicle, and
It is determined that the vehicle is starting by the means for determining whether or not the vehicle is starting
Time and the means for detecting vehicle slip
Energy that activates the front wheel motor when
Energy supply by the means for opening and closing the energy supply path
Open the route to enable driving of the front wheels, while at other times
Energy by the means for opening and closing the energy supply path
Processing means for closing the energy supply path and disabling the front wheels,
Open and close the energy supply path to operate the front wheel motor
Means closes the energy supply path and drives the front wheels.
When the motor is disabled, the electric current flowing through the rear wheel motor
Means for detecting flow, and detecting the speed of the vehicle.
Means for detecting a rear wheel rotation speed;
The rear wheel rotation speed detected by the means for detecting the rotation speed
Processing means for calculating the vehicle speed from the rear wheel rotation speed.
Processing means for calculating a vehicle speed change rate from the speed of the vehicle
When, the first determining means, the rear wheel drive motor to determine whether exceeds a first threshold the processing means vehicle speed change rate calculated by calculating a vehicle speed change rate is provided in advance A second determining means for determining whether or not the current detected by the means for detecting a current flowing through a second threshold value provided in advance, and the first determining means determining whether the current detected by the first determining means is equal to the first threshold value. A processing means for determining occurrence of slip only when the threshold value is exceeded and the second determination means determines that the second threshold value is not exceeded.

According to a third aspect of the present invention, in the drive control device for a reach type forklift, the means for detecting a slip includes only the first threshold value or the first threshold value and the second threshold value. Both of the threshold values may be adjusted by a mechanism for adjusting the voltage applied to the front wheel motor and the rear wheel motor, or a mechanism for adjusting the rate of increase of the voltage until the voltage adjusted by the mechanism is reached. There is provided a means for changing the amount of operation in accordance with the amount of operation based on a predetermined correlation between the amount of operation and each of the threshold values.

According to a fourth aspect of the present invention, the voltage applied to the front wheel motor and the rear wheel motor is an average voltage determined based on a duty ratio adjusted by chopper control. The mechanism for adjusting the voltage applied to the front wheel motor and the rear wheel motor has an accelerator lever and means for varying the duty ratio according to the operation amount of the lever, and the front wheel motor The mechanism for adjusting the rate of increase of the voltage until the voltage adjusted by the mechanism for adjusting the voltage applied to the rear wheel motor reaches the voltage adjusted by the mechanism includes at least two or more kinds of preset operation amounts of the lever. From the time-dependent increase pattern of the duty ratio until it reaches the corresponding duty ratio,
Only when it is determined that the vehicle is starting by the means for selecting one of the means and the means for determining whether the vehicle is starting or not, the duty ratio of the duty ratio selected by the means for selecting the time-dependent increase pattern of the duty ratio is selected. Processing means for increasing the duty ratio over time according to the aging increase pattern.

According to a fifth aspect of the present invention, in the drive control device for a reach-type forklift, when the energy supply path is closed and the front wheels cannot be driven by the means for opening and closing the energy supply path for operating the front wheel motor,
Means for determining whether the current detected by the means for detecting the current flowing to the rear wheel motor has exceeded a third threshold value set in advance, and detecting the current flowing to the rear wheel motor. Means for judging whether or not the current detected by the means has exceeded a fourth threshold value which is variable based on a predetermined fixed correlation with the voltage applied to the rear wheel motor. When it is determined that the current has exceeded one of the thresholds at least by the means, the motor for the front wheels and the motor for the rear wheels continue until the current falls below the thresholds. The energy supply path is opened by the processing means for stopping the voltage and the means for opening and closing the energy supply path for operating the front-wheel motor, prior to the operation amount of the mechanism for adjusting the voltage applied to the front wheel. Drivable To, the current flowing through the motor front wheel
Means for detecting, both the front wheel motor and the rear wheel motor
Means for detecting the total current flowing to the front wheel motor, wherein the current detected by the means for detecting the current flowing to the front wheel motor is lower than a preset fifth threshold value. Means for judging whether or not the threshold value has been exceeded, and the current detected by the means for detecting the total current flowing through both the front wheel motor and the rear wheel motor is a predetermined third current. Means for determining whether a threshold has been exceeded;
The current detected by the means for detecting the total current flowing through both the front wheel motor and the rear wheel motor is a predetermined predetermined correlation between the voltage applied to the front wheel motor and the rear wheel motor. A means for determining whether or not a sixth threshold that can be varied based on the threshold value, and at least one of the three means for determining, when it is determined that the current has exceeded the threshold value, Until the current falls below the threshold, there is provided processing means for stopping the voltage prior to the operation amount of the mechanism for adjusting the voltage applied to the front wheel motor and the rear wheel motor. .

In the drive control device for a reach type forklift according to claim 6, when the energy supply path is opened by the means for opening and closing the energy supply path for operating the front wheel motor, and the front wheels can be driven,
The rate of increase of the voltage until reaching the voltage adjusted by the mechanism for adjusting the voltage applied to the front wheel motor and the rear wheel motor is prioritized over the operation amount of the mechanism for adjusting the increase rate. There is provided processing means for following the provided temporal increase pattern.

In the drive control device for a reach type forklift according to claim 7, the voltage applied to the front wheel motor and the rear wheel motor is adjusted when the energy supply path is opened and the front wheel is drivable. Means are provided for lowering the maximum voltage adjustable by the mechanism below the maximum voltage when the energy supply path is closed and the front wheels cannot be driven.

[0030] In the drive control apparatus for a reach-type forklift according to claim 8, a voltage front wheel is applied to the wheel drive motor after a time of non-drivable, for front wheel drive motor and rear wheels when the front wheels are drivable When the voltages applied to the motor are the same, the sixth threshold value is set lower than the fourth threshold value when both voltages are equal to or higher than a predetermined value, and when both voltages are equal to or lower than the predetermined value, the sixth threshold value is set. Are set higher than the fourth threshold.

In the drive control device for a reach type forklift according to the ninth aspect, it is determined whether or not the speed detected by the means for detecting the speed of the vehicle exceeds a predetermined seventh threshold value. When the determining means determines that the speed of the vehicle exceeds the seventh threshold value, the energy supply path for opening and closing the energy supply path for operating the front wheel motor is closed and the front wheels cannot be driven. And a processing means for maintaining the closed state of the energy supply path even when the energy supply once falls below the seventh threshold and falls below the seventh threshold again.

[0032]

According to the drive control device for a reach-type forklift according to the first aspect, the drive of the front wheels is switched between the drive enabled and the drive disabled, the speed of the vehicle is detected, and it is determined from the speed whether or not the vehicle is starting. It is determined whether or not there is a slip when the vehicle starts. And only when the vehicle starts and slips
The front wheels can be driven, otherwise the front wheels
Driving is disabled. When the vehicle starts and slips
Energy supply to the front wheel motor
After a certain period of time when the path opens and the front wheels are
After waiting, the front wheels are actually driven. Again
After a certain time, mechanical loss braking is performed, and the wheel rotation speed is reduced.
Slow down.

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] According to the driving control device of the reach forklift according to claim 2, the electric motor by an electric energy
Drive the front and rear wheels to drive the front wheels,
Function, and detects the speed of the vehicle.
The vehicle determines whether or not the vehicle has started, and determines when the vehicle starts to slip.
The presence or absence of a loop. And when the vehicle starts and slips
The front wheels can be driven only when the
The front wheels are disabled, and the front wheels are disabled.
Is detected, the current flowing to the rear wheel motor is detected.
You. Further, the rotation speed of the rear wheel is detected, and from the rotation speed of the rear wheel,
Calculate the vehicle speed and calculate the vehicle speed change rate from the vehicle speed.
Is calculated. When the rate of change in vehicle speed exceeds the first threshold value and the current flowing through the rear wheel motor does not exceed the second threshold value, it is determined that a slip has occurred.

According to the drive control apparatus for a reach-type forklift according to the third aspect , the threshold value of the current flowing to the rear wheel motor or the threshold value of both the current and the rate of change of the rear wheel rotational speed are set at the front wheel. A mechanism that adjusts the voltage applied to the motor for the rear wheel and the motor for the rear wheel, or a mechanism that adjusts the rate of increase of the voltage until the voltage adjusted by the mechanism is reached, according to the amount of operation. It changes based on the correlation.

According to the drive control device for a reach type forklift according to the fourth aspect , when the accelerator lever is operated,
An average voltage based on the duty ratio controlled by the chopper according to the operation amount of the lever is applied to the front wheel motor and the rear wheel motor. Also, when starting by operating the lever,
The duty ratio reaches the duty ratio corresponding to the operation amount of the lever while the duty ratio increases with time according to the time-dependent increase pattern of the duty ratio selected in advance.

According to the drive control apparatus for a reach-type forklift according to the fifth aspect , when the front wheels cannot be driven, the current flowing through the rear wheel motors is equal to the third threshold value and the rear wheel motors. When at least one of the fourth thresholds that vary based on a predetermined fixed correlation with the voltage to be applied exceeds one of the thresholds, the current raises the threshold. The application of the voltage to the rear wheel motor is stopped until the voltage falls below the threshold.

On the other hand, when the front wheels are drivable, the current flowing through the front wheel motor sets a fifth threshold value lower than the third threshold value to the values of the front wheel motor and the rear wheel motor. If the total current flowing in both is the third threshold,
When at least one of the sixth thresholds, which varies based on a predetermined predetermined correlation between the voltage applied to the front wheel motor and the voltage applied to the rear wheel motor, exceeds at least one of them, the current that exceeds The voltage application to the front wheel motor and the rear wheel motor is stopped until the value falls below the threshold value.

According to the drive control apparatus for a reach-type forklift according to the sixth aspect , when the front wheels are drivable, the mechanism is adjusted by the mechanism for adjusting the voltage applied to the front wheel motor and the rear wheel motor. The rate of increase of the voltage until the voltage is reached does not follow the mechanism for adjusting the rate of increase, but increases with time according to a time-dependent increase pattern provided separately.

[0044] According to the driving control device of the reach forklift according to claim 7, the maximum voltage that can be applied to the front wheel drive motor and rear wheel drive motor when the front wheel can be driven, the front wheels becomes non-drivable Lower than when you are.

[0045] According to the driving control device of the reach forklift according to claim 8, rear and voltage front wheel is applied to the wheel drive motor after a time of non-drivable, and the front wheel drive motor when the front wheel is drivable wheels When the voltage applied to the motor for
If the voltages are equal to or higher than a certain value, the sixth threshold value is lower than the fourth threshold value. Higher.

According to the drive control apparatus for a reach-type forklift according to the ninth aspect , when the vehicle speed becomes equal to or higher than the seventh threshold value, the energy supply path of the front wheel motor is closed, and the front wheels cannot be driven. . Even after that, even if the value falls below the seventh threshold value again, the state in which the energy supply path is closed is maintained, and the front wheels are maintained in a state where they cannot be driven.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 to 3, a pair of right and left legs 2 are provided on the front side of the vehicle 1 in the reach type forklift.
L and 2R are provided to extend, and a mast M movable in the front-rear direction is provided between the legs 2L and 2R. A pair of left and right forks F are provided on the front side of the mast M, and the forks F are configured to move up and down along the mast M.

Outside the rear ends of the legs 2L and 2R, electric motors for left and right front wheels (hereinafter, “electric motors for front wheels”) are provided.
Simply referred to as "front wheel drive motor") 5L, 5R are provided. Also, outside the front ends of the legs 2L, 2R, the left and right front wheels 4 connected to the left and right front wheel motors 5L, 5R via a left and right gear box 3L, 3R so as to be able to transmit drive.
L and 4R are disposed rotatably.

As shown in FIG. 2, a rear wheel 7 serving as a steering wheel and a driving wheel is provided on the lower left side of the vehicle 1, and a caster wheel 8 is also provided on the right side. As shown in FIG. 3, an electric motor for a rear wheel (hereinafter, simply referred to as a “ motor for a rear wheel ”) that rotationally drives the rear wheel 7 is provided inside the vehicle 1.
Are arranged. As shown in FIGS. 3 and 4, a brake disk 16 having ribs 19 provided at regular intervals penetrates a rotating shaft 17 of the rear wheel motor 9, and furthermore, a very small amount of A rear wheel rotational speed sensor 6, which is, for example, a magnetic sine wave generator, is provided so as to keep a constant interval. The rear wheel rotation speed sensor 6 captures a change in magnetic flux generated every time the rib 19 of the brake disk 16 that rotates integrally with the rotation shaft 17 passes, converts the change into a sine wave voltage, and rotates the rear wheel 7. The speed R is output to a controller 23 described later. Accordingly, the rear wheel rotational speed sensor 6 is not limited to a magnetic sine wave generator as long as a signal indirectly representing the rotational speed is obtained. For example, a magnetic pulse generator that generates a pulse voltage may be used. Or a type such as an encoder.

A driving force is transmitted from the rear wheel motor 9 to the rear wheel 7 via a drive unit 90 . Further, a drive unit gear 10 is horizontally fixed to the upper end of the drive unit 90.
90 , the rear wheel motor 9 and the rear wheel 7 are integrally rotatable in the steering direction of the rear wheel 7.

A steering gear 21 is provided at the tip of the steering shaft 18 so as to mesh with the drive unit gear 10. The drive unit gear 10 has a detection gear 11 a of a steering angle sensor 11.
Are provided so as to be meshable.

The rear wheel 7 is driven by a steering motor (not shown) based on the amount of rotation of a steering wheel H provided on the driver's seat W of the vehicle 1 to rotate the steering shaft 18 so that the steering gear 21 The steering is performed via the drive unit gear 10. The steering angle θ at that time is determined by the steering angle sensor 11.
And output to the controller 23 described later.

The driver's seat W of the vehicle 1 is provided with an accelerator lever 12 as traveling operation means. or,
The accelerator lever 12 is provided with a potentiometer 13 for detecting an operation amount S of the accelerator lever 12 and outputting it to a controller 23 described later. Further, the accelerator lever 12 is provided with an operation direction switch 14 for detecting the operation direction of the accelerator lever 12 and outputting the detected operation direction as a traveling direction D of the vehicle 1 to a controller 23 described later.

A drive control device 20 for controlling the driving of the left and right front wheel motors 5L, 5R and the rear wheel motor 9 is provided inside the vehicle 1. Next, the electrical configuration of the drive control device 20 will be described below.

As shown in FIG . 5, the drive control device 20
Is composed of a rear wheel drive circuit section 21, a front wheel drive circuit section 22, and a controller 23, which are connected to a battery 24 as a DC power supply.

The rear-wheel drive circuit 21 is a circuit for driving the rear-wheel motor 9. One of the terminals of the rear-wheel motor 9 is connected via the regenerative contactor 25 and the other is connected to the switching terminal. They are connected to the minus side and plus side of the battery 24, respectively, via a main transistor 28 or the like as an element.

A rear wheel forward contactor 26 and a rear wheel reverse contactor 27 are connected to the field winding 9b. The direction of the magnetic field current flowing through the field winding 9b is changed by the complementary switching operation of the two contactors 26 and 27, so that the rear wheel motor 9 is normally or reversely rotated.

The main transistor 28 has a collector terminal connected to the rear wheel forward contactor 26 and the rear wheel reverse contactor 27, and an emitter terminal connected to the negative side of the battery 24. Therefore, the main transistor 28 is connected in series to the rear wheel motor 9. A known chopper signal from the controller 23 is input to the base terminal.
The main transistor 28 may be of any type such as a bipolar transistor, SIT, or FET. However, in the case of SIT or FET, the collector terminal changes to a drain terminal, the emitter terminal changes to a source terminal, and the base terminal changes to a gate terminal.

The flywheel diode 29 has an anode connected to the rear wheel contactor 26 of the field winding 9b and a cathode connected to the + side of the battery 24. The flywheel diode 30 has an anode connected to the rear wheel contactor 27 of the field winding 9b and a cathode connected to the + side of the battery 24.

The total current sensor 31 is connected between the rear wheel motor 9 and the regenerative contactor 25, detects the total current It supplied from the battery 24, and outputs it to the controller 23. I have.

The total current It detected by the total current sensor 31 is equal to the left and right front wheel motor contactors 41 and 4.
0 is on and the left and right front wheels 4L, 4R are drivable, which means the current flowing through both the left and right front wheel motors 5L, 5R and the rear wheel motor 9, but not both contactors. 40, 41 turn off, front left and right wheels 4L, 4R
Is incapable of driving, it means a current flowing only to the rear wheel motor 9. That is, the total current sensor 31, when the left and right front wheels 4L, 4R can be driven detects the total current flowing through the left and right front wheel drive motor 5L, 5R, both及beauty rear wheel motor 9 sensor When the left and right front wheels 4L, 4R cannot be driven, they function as sensors for detecting the current flowing through the rear wheel motor 9.

The regeneration transistor 32 has a collector connected to the + terminal of the battery 24, and an emitter connected to the rear wheel contactor 2 of the armature 9 a via the regeneration resistor 33.
6 and the rear wheel reverse contactor 27 side.

The regenerative diode 34 has a cathode connected to the armature 9 a side of the regenerative contactor 25 and an anode connected to the negative side of the battery 24. The well-known snubber circuit 36 includes a collector of the main transistor 28.
It is connected in parallel between the emitters.

The front wheel drive circuit section 22 is a circuit for driving the left and right front wheel motors 5L and 5R. The right front wheel motor 5R and the left front wheel motor 5L are magnet type DC motors. And the field magnets 5Lb and 5Rb. The right front wheel motor 5R is connected in series with a right motor contactor 40 as opening / closing means, and the left front wheel motor 5L is similarly connected in series with a left motor contactor 41 as opening / closing means. Also, the right motor contactor 40
And the right front wheel motor 5R, and the left motor contactor 41 and the left front wheel motor 5L are connected in parallel. The contactors 40 and 4 which are means for opening and closing the electric energy supply path to the left and right front wheel motors 5L and 5R.
1 is turned on in response to a control signal from the controller 23.
Off control is performed to switch between driving and non-driving of the left and right front wheels 4L and 4R.

Further, to both ends are connected a front wheel forward contactor 42 and a front wheel reverse contactor 43. The direction of the current flowing through the armatures 5La, 5Ra is changed by the complementary switching operation of the two contactors 42, 43, and the right front wheel motor 5R and the left front wheel motor 5L rotate forward and backward. .

The right front wheel motor 5R and the left front wheel motor 5L are connected at one end to the full current sensor 31 of the armature 9a via a front wheel forward contactor 42 and a front wheel reverse contactor 43. The other end is connected to the collector side of the main transistor 28. Therefore,
The rear wheel motor 9, the right front wheel motor 5R, and the left front wheel motor 5L are connected in parallel to the battery 24.

The front wheel current sensor 46 is provided between the front wheel forward contactor 42 and the front wheel reverse contactor 43 and the armature 9a.
Of the contactor 25 for regeneration. The front wheel current sensor 46 detects front wheel current If supplied to the left and right front wheel motors 5L and 5R, and
Is output.

The anode of the flywheel diode 44 has a right front wheel motor 5R and a left front wheel motor 5L.
Is connected to the front contactor 42 side, and the cathode is connected to the regeneration contactor 25 side of the armature 9a. The flywheel diode 45 has its anode connected to the front wheel reverse contactor 43 of the right front wheel motor contactor 40 and left front wheel motor contactor 41, and its cathode connected to the regenerative contactor 25 side of the armature 9a. Have been.

The controller 23 is connected between the + and-terminals of the battery 24. The electrical configuration of the controller 23 will be described below with reference to FIG.

The controller 23 includes a control unit (hereinafter referred to as a CPU).
And a storage unit 51. Storage unit 5
1, a control program for operating the CPU 50 is stored. This control program is based on the operation amount S, the steering angle θ, the traveling direction D, the rotation speed R, the total current It, and the front wheel current If, and the contactors 25, 26,
27, 40, 41, 42, and 43 are provided. Also, turn on the regeneration transistor 32.
It has a program to instruct turning off. Further, it has a program for generating a chopper signal for driving the main transistor 28 based on the operation amount S.

The storage unit 51 stores maps shown in FIGS. 7 and 8 for determining the target duty ratio of the chopper signal with respect to the operation amount S of the accelerator lever 12 detected by the potentiometer 13. Of the two maps, the map in FIG. 8 indicates the time when the forklift is started and the slip is detected (hereinafter, referred to as a slip start mode), that is, the left and right front wheels 4L and 4R and the rear wheel 7 described later. Are driven together (except at the time of switchback described later; the same applies hereinafter), showing the correlation between the manipulated variable S and the target duty ratio M1. Similarly, the map of FIG. 7 shows the manipulated variable S and the manipulated variable S at the time of starting, when no slip is detected, and after starting (hereinafter referred to as a standard mode), that is, when only the rear wheels 7 are driven. This shows the correlation between the target duty ratio M2. Then, based on the rotation speed R and the total current It, either of the two modes is determined by a control program described later in detail, and these two maps corresponding to each of the two modes are used properly.

In the slip start mode map, the maximum value of the target duty ratio M1 that can be adjusted by the operation amount S is set lower than the same maximum value of the target duty ratio M2 in the standard mode map. In both maps, the target duty ratios M1 and M2 corresponding to the same operation amount S until the maximum value is reached are the same, so that the target duty ratio in the slip start mode map is larger than that in the standard mode map. The manipulated variable S that reaches the maximum value of the ratio M1
Becomes smaller.

The storage unit 51 stores the data shown in FIGS.
A map for determining the total current threshold value for the voltage applied to the left and right front wheel motors 5L, 5R and the rear wheel motor 9 is stored. Of the two maps, the map of FIG. 9 shows the correlation between the voltage applied to the rear wheel motor 9 and the total current threshold L4, which is the fourth threshold, in the standard mode. Similarly, the map of FIG. 10 shows the left and right front wheel motors 5L, 5L in the slip start mode.
R and a voltage applied to the rear wheel motor 9 and a correlation between the total current threshold L6 as a sixth threshold. Then, based on the rotation speed R and the total current It, either of the two modes is determined by a control program described later in detail, and these two maps corresponding to each of the two modes are used properly.

When the voltage in the standard mode is the same as the voltage in the slip start mode, when the voltages are equal to or lower than a certain voltage (less than 2 V), the value of the total current threshold value L6 according to the slip start mode map Is higher than the value of the total current threshold L4, which also follows the map in the standard mode. On the other hand, above the certain voltage, the opposite is true.
As will be described in detail later, in the slip start mode, a sufficient driving force is ensured at a voltage lower than the predetermined voltage, and a slip is generated due to an excessive driving force at the voltage higher than the predetermined voltage.

The CPU 50 includes the potentiometer 1
The operation amount S of the accelerator lever 12 detected by 3 is input via the A / D converter 52. Similarly, the traveling direction D of the operation direction switch 14 is input to the CPU 50. Similarly, the steering angle θ detected by the steering angle sensor 11 is input to the CPU 50 via the A / D converter 53. Similarly, the rotation speed R detected by the rear wheel rotation speed sensor 6 is input to the CPU 50 via the filter 54.

The CPU 50 calculates the vehicle speed at that time based on the rotational speed R, and determines whether or not the vehicle is starting. From the vehicle speed of zero (stopped state),
The time until the vehicle reaches the start end vehicle speed L7, which is the seventh threshold value stored in the storage unit 51 in advance, is regarded as the start time, and the other time is regarded as the travel time. That is, when the vehicle speed is equal to or higher than the start end vehicle speed L7, the start end vehicle speed L
Even 7 or less, if it falls below once again from beyond the emitting advance end car speed L7, as long as you do not start completely again stopped regarded as a time of traveling.

Further, the CPU 50 calculates a vehicle speed change rate within a predetermined time based on the vehicle speed. The front wheel current If detected by the front wheel current sensor 46 is input to the CPU 50 via a noise removing filter 61 and an A / D converter 62. The front wheel current If is also input to the comparator 63 via the filter 61. The comparator 63 calculates the front wheel current If and a fifth threshold overcurrent limit value (hereinafter referred to as a front wheel OCL value) set by a front wheel overcurrent limit value setting circuit (hereinafter referred to as a front wheel OCL setting circuit) 64. Call).

The front wheel OCL value is a maximum allowable current for preventing the magnets of the left and right front wheel motors 5L and 5R, which are magnet type motors, from being demagnetized, and is determined and set in advance by a test or calculation. Then, the front wheel OCL setting circuit 6
4 includes a front wheel OCL value L5S when one of the left and right front wheel motors 5L and 5R is driven, and a front wheel OCL value L5 when both the left and right front wheel motors 5L and 5R are driven.
Two types of W are set.

The front wheel OCL setting circuit 64 calculates a front wheel OCL value L5S when one of the left and right front wheel motors 5L and 5R is driven, and a front wheel OCL value when both the left and right front wheel motors 5L and 5R are driven. L5W is output to the comparator 63. Then, the comparator 63 compares the front wheel current If with the front wheel OCL value L5S (or L5W), and outputs an H level first limit signal S1 to the CPU 50 when the front wheel drive current If is larger.

The CPU 50 includes the all-current sensor 3
1 is the total current It detected by the filter 6 for removing noise.
5 through the A / D converter 66. Note that the total current It is also input to the comparator 67 via the filter 65. The comparator 67 calculates the total current It and the front and rear wheel overcurrent limit value setting circuit (hereinafter, referred to as front and rear wheel OCL setting circuit).
An overcurrent limit value (hereinafter, referred to as a front and rear wheel OCL value) L3 which is a third threshold value set at 68 is compared.

The front and rear wheel OCL values L3 are the maximum allowable currents for preventing the main transistor 28 from being destroyed, and are determined and set in advance by tests or calculations. Front and rear wheel OC
L setting circuit 68 is adapted to as to output the wheel OCL value L3 to the ratio 較器6 7 back and forth. Then, the ratio 較器6 7 compares the total current It and the front and rear wheels OCL value L3, when the larger total current It, the second restriction signal S2 H level CPU
Output to 50.

The map shown in FIG. 11 is stored in the storage unit 51. This map shows the relationship between the manipulated variable S and the second threshold value, that is, the total current threshold value L2, in the standard mode, that is, when both of the contactors 40 and 41 are turned off and only the rear wheel 7 is driven. The correlation is shown. Further, the storage unit 51 stores a vehicle speed change rate threshold L1, which is a first threshold.

When the CPU 50 determines that the vehicle is starting from the calculated vehicle speed, the total current It is determined by the total current threshold L2.
When it is determined that the vehicle speed change rate exceeds the threshold value L1 and the calculated vehicle speed change rate exceeds the vehicle speed change rate threshold value L1, the occurrence of slip is determined.

The storage unit 51 stores at least a time-dependent increase pattern of the duty ratio for determining the increase rate until reaching the target duty ratio M2 corresponding to the operation amount S determined according to the map of FIG. Two or more types ( Fig. 1
Eight) a map set in 2 are stored. The pattern of increasing the duty ratio over time used is the driver's seat W
The one suitable for the situation is selected by the operator in advance from the two or more kinds of the time-dependent increase patterns of the duty ratio by a selecting means (not shown) provided in the above. CPU 50
The ratio with respect to the target duty ratio M2 is determined according to the time-dependent increase pattern of the duty ratio in the map of FIG. 10
0%, that is, a control signal for increasing to the target duty ratio M2 is output.

Further, the storage unit 51 stores FIG.
A map in which a time-dependent increase pattern of the duty ratio that determines the increase rate until reaching the target duty ratio M1 corresponding to the operation amount S determined according to the map of FIG. I have. CPU 50
When the vehicle speed is determined to be starting from the calculated vehicle speed and when it is determined that a slip has occurred, that is, only in the slip starting mode, priority is given to the map of FIG. 12 according to the duty ratio aging increase pattern in the map of FIG. , The ratio to the target duty ratio M1 is increased to 100%, that is, to the target duty ratio M1. It should be noted that the target duty M1 according to the aging increase pattern of the map of FIG.
Is less than or equal to the ratio of the lowest temporal increase pattern according to the map of FIG. 12 to the target duty M2.

The CPU 50 includes contactors 26 and 27 for rear wheel forward and rear wheel reverse, contactors 42 and 43 for front wheel forward and rear wheel forward, contactors 40 and 41 for right front wheel and left front wheel motor, and a contactor 25 for regeneration. A drive signal for driving an excitation coil (not shown) for turning on / off is output to each of the coil drive circuits 69a to 69g. The details will be described below.

When the CPU 50 determines that the vehicle is in the slip start mode, the CPU 50 outputs a drive signal for turning on the contactors 41 and 40 to the coil drive circuits 69e and 69f. On the other hand, at other times, that is, when it is determined that the mode is the standard mode, a drive signal for turning off is similarly output. Upon receiving the drive signal, the coil drive circuits 69e and 69f turn on and off the contactors 40 and 41. In other words, the left and right front wheels 4L and 4R can be driven in the former case, and cannot be driven in the latter case. The term “impossible to drive” as used herein means a driven wheel that is in a rotating state in which the driving force is not transmitted. (Hereinafter the same) Meanwhile, starting at A, as described above, it is until the vehicle speed reaches the starting ends vehicle speed L7 is a seventh threshold from zero. Therefore, CP
U50 is, the slip start mode, i.e. at the start, and when it is determined that slip occurs, after the left and right front wheels 4L, 4R becomes drivable, the starting ends vehicle speed the vehicle speed is increased L7
Then, the left and right front wheels 4L, 4R are switched to the non-driveable state. Then, the vehicle speed decreases, and the starting end speed is again increased.
Even if the temperature falls below the degree L7 , unless the vehicle completely stops and then starts again, it is not considered to be at the time of starting, so that the left and right front wheels 4L and 4R are not switched to be driven again.

The controller 23 immediately starts the slip start mode and immediately starts the two contactors 40, 41.
During the so-called delay time until the
The output of the chopper signal to the main transistor 28 is cut off, and the power supply is stopped. Specifically, the output of the chopper signal from the CPU 50 to the AND circuit 70 described later is stopped.

Further, after stopping the output of the chopper signal, the CPU 50 stores the data in the storage unit 51, and after elapse of a predetermined time previously obtained by experiments and calculations, the CPU 50 shown in FIGS. 8 and 13 described above. The output of the chopper signal is restarted according to the map.

The CPU 50 controls the coil drive circuit 6 to turn on / off the left and right front wheel motor contactors 41 and 40.
The drive signals output to 9e and 69f are output to the front wheel OCL setting circuit 64. Then, the front wheel OCL setting circuit 64
The front wheel OCL value L5 depends on the presence or absence of these two drive signals.
S, has become as outputs one of L5W the ratio 較器6 3. That is, when both contactors 40 and 41 are turned on, the front wheel OCL setting circuit 64 controls the front wheel OCL value L5W.
When only one of them is turned on, the front wheel OCL value L5S is output.

In the standard mode, the CPU 50 transmits a chopper signal of the target duty ratio M2 to the operation amount S of the accelerator lever 12 via the AND circuit 70 according to the map shown in FIG.
Output to the base terminal. Also, CPU5
0 indicates that the chopper signal of the target duty ratio M1 with respect to the operation amount of the accelerator lever 12 in the slip start mode is in accordance with the map shown in FIG.
And outputs the signal to the base terminal of the main transistor 28.

Further, when the vehicle 1 determines that the vehicle 1 is in the slip start mode, the CPU 50 determines whether the left and right front wheel motor contactors 4 are based on the steering angle θ detected by the steering angle sensor 11.
On / off control of 1, 40. That is, when the vehicle 1 makes a right turn and the steering angle θ turns to the right by 33 ° or more to the left, C
The PU 50 outputs a signal for turning off the right front wheel motor contactor 40 to the coil drive circuit 69e. Then, the CPU 50 shuts off the power supply of the right front wheel motor 5R to make it free, so that the right front wheel 4R becomes a driven wheel.

Similarly, when the vehicle 1 makes a left turn and the steering angle θ turns to the left by 40 ° or more to the right, the CPU 50 outputs a signal for turning off the left front wheel motor contactor 41 to the coil drive circuit 69f. It is supposed to. And C
The PU 50 cuts off the power supply of the left front wheel motor 5L to make it free, so that the left front wheel 4L becomes a driven wheel.

The turning control at the time of the start is such that the right front wheel 4R serving as the inner wheel is slower in turning speed than the left front wheel 4L serving as the outer wheel in the right turning, and the left front wheel 4L serving as the inner wheel is opposite to the outer wheel in the left turning. The turning speed becomes slower than the right front wheel 4R.
As a result, the armature current of the inner wheel motor having a low turning speed increases, and the armature current of the outer wheel motor having a high turning speed decreases. Therefore, in this embodiment, the armature current of the motor on the inner wheel side is prevented from exceeding the permissible current, and the armature current of the motor on the outer wheel side is reduced to prevent a reduction in driving capability.

In the present embodiment, when the turning speed ratio between the right front wheel 4R and the left front wheel 4L is reduced to 60% or less in a test in advance, the power supply to the inner wheel side motor is cut off. That is, the steering angle θ at which the turning speed ratio becomes 60% or less is 33 ° or more to the left in the case of a right turn, and 40 ° or more to the right in the case of a left turn. It is to be noted that the steering angle is different between the right turn and the left turn because the rear wheels 7 are eccentrically located on the left side with respect to the vehicle 1 as shown in FIG. This is because in each case, the turning radius of the right front wheel 4R and the turning radius of the left front wheel 4L are different from each other.

A series of controls based on the steering angle θ detected by the steering angle sensor 11 are performed only in the slip start mode, and are not performed in the standard mode. That is, in the standard mode, the two contactors 4 described above are used.
0, 41 are turned off, and the control for maintaining the left and right front wheels 4L, 4R incapable of driving has priority. On the other hand, in the slip start mode, control based on the steering angle θ detected by the steering angle sensor 11 described above is given priority. Therefore, in the slip start mode, the steering angle θ is less than 33 ° to the left,
Alternatively, when the steering angle θ is less than 40 ° to the right, both the left and right front wheels 4L and 4R can be driven.
Alternatively, when the steering angle is more than 40 ° to the right, the left and right front wheels 4L, 4L are controlled according to the steering angle θ detected by the steering angle sensor 11.
Only one of the 4Rs can be driven and the other is a driven wheel.

When the vehicle 1 is driving forward,
When the accelerator lever 12 is operated in the reverse direction from the forward direction through the neutral position, the CPU 50 determines that the operation is the switchback operation. At this time, the CPU 50 switches the rear-wheel forward and rear-wheel reverse contactors 26 and 27 to the direction in which the rear-wheel motor 9 is driven backward. The same applies to the case where the vehicle is being driven in reverse. Even if the accelerator lever 12 is operated from the reverse direction to the forward direction via the neutral position, the CPU 5
0 is determined as a switchback operation.

When the switchback operation is performed, the CPU
50 is a right front wheel and left front wheel motor contactor 40, 4
1 is on, that is, in the slip start mode, the contactors 40 and 41 are turned off, while the contactors 40 and 41 are turned off.
When 41 is off, that is, in the standard mode, both contactors 40 and 41 are kept off as they are. That is,
When the CPU 50 determines that the operation is the switchback operation,
Regardless of the standard mode or the slip start mode, the contactors 40 and 41 are turned off.

At the same time, the CPU 50 determines whether or not the vehicle speed at that time is at a speed at which regenerative braking can be performed. The vehicle speed at which the regenerative braking can be performed is determined in advance by a test or an experiment. When the current vehicle speed is within the regenerable braking speed, the CPU 50 turns off the regenerative contactor 25 to perform the regenerative braking.

The CPU 50 turns on the main transistor 28 and the regenerating transistor 32 to perform a known pre-excitation, and when the pre-excitation ends, the main transistor 28
Then, the regeneration transistor 32 is turned off. CPU 50
Generates a regenerative current based on the preliminary excitation.

This regenerative current is detected by the all current sensor 31, and the regenerative current value is output to the CPU 50. Then, when the regenerative current becomes equal to or more than a predetermined allowable current value,
The CPU 50 controls the main transistor 28 by chopper control to suppress the regenerative current. This allowable current value is stored in the storage unit 51 in advance.
Is stored as a map (not shown). This map shows the correlation between the operation amount S and the allowable current value of the regenerative current in the switchback operation of the accelerator lever 12 at that time, and the allowable current value increases in proportion to the operation amount S. ing.

When the vehicle speed becomes a speed at which regenerative braking cannot be performed, the CPU 50 shifts to plugging braking. CPU 50
Switches the rear-wheel forward and rear-wheel reverse contactors 26 and 27 so that the rear-wheel motor 9 is driven backward through the coil drive circuits 69a and 69b, and the left and right front wheels via the coil drive circuits 69c and 69d. The front-wheel forward contactors and the front-wheel reverse contactors 42 and 43 are switched so that the motors 5L and 5R are driven backward. The CPU 50 turns on the regenerative contactor 25 via the coil drive circuit 69g. The CPU 50 performs chopper control of the main transistor 28 at a duty ratio with respect to the operation amount S in the switchback operation of the accelerator lever 12 at that time. That is, the CPU 50 rotates the rear wheel motor 9 in the reverse direction and drives it backward to execute plugging braking. If the vehicle speed is such that regenerative braking cannot be performed when the switchback operation is performed, the CPU 50 immediately starts control for plugging braking without performing regenerative braking.

In the present embodiment, the motor 9 for the rear wheel is used for both the regenerative braking and the plugging braking.
But it is not limited to this, for example,
During both braking operations, both the left and right front wheel motors 5L, 5R and the rear wheel motor 9 may be operated. However, in this case, it goes without saying that control for turning on the right front wheel and left front wheel motor contactors 40 and 41 is required.

If both the regenerative braking and the plugging braking are applied to both the left and right front wheel motors 5L, 5R and the rear wheel motor 9, the braking force increases, but the circuit configuration becomes complicated. .

[0106] The ratio 較器7 4, and the total current It is digitally converted by the A / D converter 66, FIG. 9 and the output from the CPU 50, the total current threshold based on the map shown in FIG. 10 Compare with L4 or L6.

That is, in the slip start mode, C
The PU 50 compares the total current threshold value L6 corresponding to the voltage applied to the left and right front wheel motors 5L, 5R and the rear wheel motor 9 with the comparator 74 based on the map shown in FIG.
Output to The comparator 74 compares the total current It with the total current threshold L6, and outputs an H-level third limiting signal S3 only when the total current It is larger.

Similarly, in the standard mode, the CPU 5
0 is a voltage applied to the rear wheel motor 9 at that time based on the map shown in FIG. 9 (in the standard mode, since the left and right front wheel contactors 41 and 40 are off as described above, the voltage is It is not applied to the front wheel motors 5L and 5R.), And outputs the total current threshold value L4 to the comparator 74. The comparator 74 compares the total current It with the total current threshold L4, and only when the total current It is larger,
A third level limit signal S3 is output.

The AND circuit 70 receives the first and second limit signals S1 and S2 via a NOT circuit 71 and OR circuits 72 and 73. Similarly, the third limiting signal S3 is input via the NOT circuit 71 and the OR circuit 72. (Since the knot circuit 71 is provided, the H-level limit signals S1, S2, and S3 are converted to L-level signals and input to the AND circuit 70.) Also, a chopper signal based on the operation amount S is The data is input from the CPU 50. Further, the output from the AND circuit 70 is output to the main transistor 28 in accordance with the above-mentioned two input states (limit signal and chopper signal). Therefore, when at least one of the limit signals S1, S2, and S3 is output, the AND circuit 70 cuts off the chopper signal from the CPU 50 to the main transistor 28.

That is, in the case of the slip start mode, the chopper signal to the main transistor 28 is stopped when at least one of the limit signals S1, S2, S3 is output, while in the case of the standard mode. The chopper signal to the main transistor 28 is stopped when at least one of the limit signals S2 and S3 is output.
Also, the chopper signal to the stopped main transistor 28 is such that all the outputs of the limit signals S1, S2, S3 are turned off.
It will be resumed when lost .

The operation of the drive control device for a reach-type forklift constructed as described above will be described below.
When the vehicle 1 is stopped, the CPU 50 performs control in the standard mode. That is, the left and right front wheel contactors 41, 40
Are turned off via the coil drive circuits 69e and 69f, the left and right front wheels 4L and 4R are kept incapable of driving, and only the rear wheels 9 can be driven. Then, for example, when the accelerator lever 12 is operated in the forward direction from the neutral position to perform forward traveling, the CPU 50 causes the rear wheel forward and rear wheels so that the rear wheel motor 9 is driven forward through the coil drive circuits 69a and 69b. The reverse contactors 26 and 27 are switched. Similarly, the CPU 50 switches the front wheel forward and front wheel reverse contactors 42 and 43 so that the left and right front wheel motors 5L and 5R are driven forward through the coil drive circuits 69e and 69f. However, as described above, the left and right front wheels 4L and 4R are kept incapable of driving. Further, the CPU 50 turns on the regenerative contactor 25 via the coil drive circuit 69g.

Subsequently, the CPU 50 selects the map in the standard mode shown in FIG. 7, and calculates the target duty ratio M2 of the chopper signal corresponding to the operation amount S of the accelerator lever 12 at that time based on the map.

Since the vehicle 1 is stopped, that is, the vehicle is traveling from the vehicle speed of zero, the CPU 50 determines that the vehicle has started. Further, based on the determination, the CPU 50 calculates the duty ratio of the chopper signal in accordance with the time-dependent increase pattern selected in advance among the two or more types of the time-dependent increase patterns set in the map shown in FIG. While increasing the target duty ratio M2, a chopper signal of the duty ratio is output to the main transistor 28 via the AND circuit 70.

The main transistor 28 is turned on / off based on the chopper signal, and the driving power is supplied from the battery 24 to the rear wheel motor 9. Then, the rear wheel motor 9 starts rotating.

By controlling the duty ratio based on the map shown in FIG. 12 at the time of starting, excessive power supply to the rear wheel motor 9 can be prevented without relying on the accelerator operation technique of the driver. And a smooth start is possible.

Further, the control of the duty ratio by the map shown in FIG.
If the speed exceeds the speed L7 even once, it will not function unless the vehicle 1 stops once thereafter.

In the reach type forklift, when a load is loaded on the fork F in a state where the fork F is reached forward, a load is applied to the front side of the left and right front wheels 4L, 4R. The wheel weight of the rear wheel 7 located on the rear side of 4R is reduced. When such a cargo handling operation is performed on a low-μ road surface such as a frozen road surface in a freezer, the rear wheel 7 easily slips when the use environment of the vehicle 1 is performed.

When the vehicle 1 starts in the standard mode, the CPU 50 determines whether the total current It does not exceed the total current threshold L2 determined by the map shown in FIG. . Further, the CPU 50 determines whether the vehicle speed change rate does not exceed a preset and stored vehicle speed change rate threshold value L1. As a result, CP
U50 indicates that the total current It is below the total current threshold L2,
When it is determined that the vehicle speed change rate exceeds the vehicle speed change rate threshold value L1, the occurrence of the slip is determined.

Here, the reason why the CPU 50 determines the occurrence of a slip according to the above-described discrimination control by using both the total current threshold value L2 and the vehicle speed change rate threshold value L1 is described below.

The rate of change of the vehicle speed is determined by the rear wheel rotational speed sensor 6
From the rotational speed R of the rear wheel 7 detected by
In general, the rotational speed of the drive wheel when the vehicle slips at the start increases sharply as compared with the rotational speed immediately before the vehicle slips because the running resistance decreases. Therefore, if the slip occurrence is determined when the vehicle speed change rate suddenly increases so as to exceed the vehicle speed change rate threshold value L1 obtained and set in advance through experiments and calculations, the slip with a certain degree of accuracy can be obtained. Can be detected.

However, the vehicle speed change rate threshold value L1
In some cases, accurate determination of a slip cannot be made by means of discriminating only by using the method. That is, reach forklift ,
Oite to slip hardly occurs high-μ road surface, fork F
When the operation amount S of the accelerator lever 12 is maximized in a state where the weight of the vehicle is lightest when no load is loaded on the vehicle and the vehicle is started without a slip, the vehicle speed change rate is such that the slip is likely to occur.
On a very low μ road surface, the operation amount S of the accelerator lever 12 is made small, and becomes larger than the vehicle speed change rate when the vehicle starts due to slippage. That is, in such a situation, the vehicle speed change rate at which no slip occurs is larger than the vehicle speed change rate at which slip occurs, so that it is impossible to determine only the vehicle speed change rate threshold L1. Become.

Therefore, in this embodiment, the total current threshold value L2 is used so that the occurrence of slip can be accurately determined even in such a situation. Generally, when a drive wheel slips, the current flowing through the motor that drives the drive wheel is lower than when the drive wheel does not slip. This is because the current flowing through the motor is proportional to the driving force of the motor. Therefore, if it is detected that the current has dropped below a predetermined threshold value, it is possible to determine the occurrence of slip.

However, this condition is satisfied only when the operation amount S of the accelerator lever 12 is the same, and is not necessarily satisfied when the operation amount S is different. That is,
As described above, if the operation amount S of the accelerator lever 12 detects the occurrence of slippage in the fine operation and the threshold value of the current flowing through the drive wheels is fixed and set, the threshold value becomes
When the operation amount S is large, the current may be lower than the current flowing to the drive wheels when no slip occurs.

In order to accurately detect the occurrence of slip without being influenced by the operation amount S of the accelerator lever 12, FIG.
Is provided based on the map shown in FIG. 3, and a total current threshold L2 that varies according to the operation amount S is provided.
In the standard mode, the total current It means a current flowing through the rear wheel motor 9). According to the total current threshold value L2 thus varied, an accurate determination can be made each time according to each operation amount S.

As described above, by using both the vehicle speed change rate threshold value L1 and the total current threshold value L2, it is possible to accurately and reliably determine the occurrence of slip. Of course, the control method for determining the occurrence of slip is not limited to the above-described content, and may be, for example, the following control method.

That is, the vehicle speed change rate threshold value L1
May be changed in conjunction with the operation amount S, similarly to the total current threshold L2. Or, the factor to be linked
Instead of the operation amount S, the duty ratio may be varied in conjunction with the selection of the time-dependent increase pattern of the duty ratio in the map shown in FIG.

If the CPU 50 determines that a slip has occurred at the time of starting, the CPU 50 immediately switches from the standard mode to the slip starting mode and performs control. That is, the left and right front wheel contactors 41 and 40 are turned on via the coil drive circuits 69e and 69f, and the left and right front wheels 4L and 4R can be driven. Also, C
The PU 50 outputs a signal for turning on the left and right front contactors 41, 40 to the coil drive circuits 69e, 69f, and simultaneously stops the chopper signal that has been output to the main transistor 28 via the AND circuit 70. . This chopper signal corresponds to the target duty ratio M2 corresponding to the operation amount S based on the map shown in FIG.
The chopper signal increases in accordance with the time-dependent increase pattern selected in the map shown in FIG. That is, the control for stopping the chopper signal is executed with priority irrespective of the control based on the maps shown in FIGS.

The stop of the chopper signal is maintained until a certain time stored in the storage unit 51 has elapsed. As described above, the fixed time is previously experimentally calculated and is not particularly limited as long as it is a value suitable for control. However, for the following reason, the CPU 50 sends the coil control circuit 69e,
It is desirable to match the so-called delay time from when the ON signal is output to the left and right front contactors 41, 40 via 69f to when the contactors 41, 40 are actually turned on.

That is, if the fixed time is shorter than the delay time, the power supply is started before the contactors 41, 40 are turned on, so that the right and left front wheel motors 5L, 5L, This is because a sudden driving force is generated in the 5R, and conversely, if the certain time is longer than the delay time, the response of the driving control is reduced.

By the way, during the stop of the chopper signal,
Since the rear wheel motor 9 does not generate a driving force, gear friction braking, which is a mechanical loss, and tire friction braking due to friction between the tire and the road surface act on the rear wheel 7. That is, the double friction braking works in a direction to suppress the slip when the rear wheel 7 starts moving, and an excellent action of functioning as a so-called traction control can be obtained.

Thereafter, when the predetermined time has elapsed, the CP
U50 selects the map in the slip start mode shown in FIG. 8, and calculates the target duty ratio M1 of the chopper signal corresponding to the operation amount S of the accelerator lever 12 at that time based on the map.

Further, the CPU 50 increases the duty ratio of the chopper signal to the calculated target duty ratio M1 according to the time-dependent increase pattern of the duty ratio in the map shown in FIG. The main transistor 28 via the circuit 70
Output again.

The main transistor 28 is turned on / off based on the chopper signal, and the driving power is supplied from the battery 24 to the rear wheel motor 9 and the left and right front wheel motors 5L and 5R. Then, the rear wheel motor 9 and the left and right front wheel motors 5L and 5R start rotating. That is,
Since the left and right front wheels 4L, 4R and the rear wheel 7 are driven by three wheels, extremely stable drive transmission is achieved as compared with the single-wheel drive of the rear wheel 7 alone in the standard mode.

As described above, in the slip start mode map shown in FIG. 8, the maximum value of the target duty ratio M1 which can be adjusted by the operation amount S is the same as that in the standard mode map shown in FIG. The target duty ratio M2 is set lower than the target duty ratio M2, thereby preventing abrupt power supply to each of the motors 5L, 5R, 9 without depending on the accelerator operation technique of the driver, and in the slip start mode. As in the standard mode, a smooth start is possible.

After the lapse of the same fixed time, FIG.
The ratio to the target duty ratio M1 according to the map of the slip start mode shown in FIG. 3 is set to be equal to or less than the ratio to the lowest target duty ratio M2 according to the map shown in FIG. , Without depending on the driver's accelerator operation technology, each motor 5L, 5R,
9 can be prevented from being suddenly supplied, and a smooth start can be performed in the slip start mode as in the standard mode.

The rear wheel motor 9, the left and right front wheel motors 5L,
When the 5R rotates, the controller 23 informs the front wheel current I
f and the total current It are input. And the front wheel current I
When f is larger than the front wheel OCL value L5W (in this case, the left and right front wheel motors 5L and 5R are both driven), the first limiting signal S1 from the comparator 64 is equal to the total current I
When t is greater than the front and rear wheel OCL value L3, the comparator 65 outputs the second limit signal S2. As a result, the output of the chopper signal to the main transistor 28 is cut off by the AND circuit 70, and the left and right front wheel motors 5L and 5R or the main transistor 28 is protected.

Similarly, when the total current It is larger than the total current threshold L6 determined based on the map shown in FIG. 10, the comparator 74 outputs the third limiting signal S3.
Is output. As a result, the output of the chopper signal to the main transistor 28 is cut off by the AND circuit 70, and an optimal driving force according to the operation amount S of the accelerator lever 12 is secured.

Then, the chopper signal is cut off, the total current It or the front wheel current If decreases, and the respective limit signals S1,
When all the outputs of S2 and S3 disappear, the chopper signal is output to the main transistor 28 again.

Incidentally, in the slip start mode,
When the steering wheel H is operated and the vehicle 1 turns right and the steering angle θ becomes 33 ° or more to the left, the CPU 50 turns off the right front wheel motor contactor 40. Therefore, the right front wheel motor 5R
The power supply is cut off and the vehicle becomes free, and the right front wheel 4R
Is the driven wheel. As a result, it is possible to prevent the armature current of the right front wheel motor 5R from increasing to an allowable current or more based on a decrease in the turning speed due to the right turn. or,
Based on the increase in the armature current of the right front wheel motor 5R, it is possible to prevent a decrease in driving force due to a decrease in the armature current of the left front wheel motor 5L having a high turning speed. Therefore, the vehicle 1 can smoothly start turning right.

Similarly, when the vehicle 1 turns left and the steering angle θ becomes 40 ° or more to the right, the CPU 50 turns off the left front wheel motor contactor 41. Therefore, the left front wheel motor 5L
The power supply is cut off and the free state is set, and the left front wheel 4L
Is the driven wheel. As a result, an increase in the armature current of the left front wheel motor 5L to an allowable current or more due to a decrease in the turning speed due to the left turn is prevented. or,
Based on the increase in the armature current of the left front wheel motor 5L, it is possible to prevent a decrease in driving force due to a decrease in the armature current of the right front wheel motor 5R having a high turning speed. Therefore, the vehicle 1 can smoothly start turning left.

Eventually, when the vehicle speed increases and reaches a predetermined start end vehicle speed L7, the CPU 50 switches from the slip start mode to the standard mode. That is, the CPU 5
0 turns off the contactors 42 and 43 for front wheel forward and rear wheel and the contactors 41 and 40 for left and right front wheel motors via the coil drive circuits 69c to 69f. Therefore, the supply of power from the battery 24 to the front wheel drive circuit section 22 is cut off, and the rotation of the left and right front wheel motors 5L and 5R is in a free state. As a result, power is supplied from the battery 24 only to the rear wheel motor 9.

The CPU 50 again selects the map in the standard mode shown in FIG. 7, and calculates the target duty ratio M2 of the chopper signal corresponding to the operation amount S of the accelerator lever 12 at that time based on the map.

As described above, the maximum target duty ratio M2 that can be adjusted based on the map of FIG.
1), and the above-described control based on the map of FIG. 12 is not performed (this control is performed only at the time of starting), so that the target vehicle speed corresponding to the target duty ratio M2 is quickly reached. I can do things.

On the other hand, if no slip occurs when the vehicle 1 starts moving, the above-described control for turning on the left and right front wheel contactors 41 and 40 by the CPU 50 is not performed, and the control for stopping the chopper signal for a certain period of time is not performed. Of course not done. Then, the CPU 50 calculates the target duty ratio M2 of the chopper signal corresponding to the operation amount S of the accelerator lever 12 at that time based on the map of the standard mode shown in FIG. 7, and the duty ratio of the chopper signal is shown in FIG. The above-described control for increasing the duty ratio to the target duty ratio M2 in accordance with the temporal increase pattern of the duty ratio of the map is continued.

Eventually, when the vehicle speed increases and reaches the predetermined starting end vehicle speed L7, the CPU 50 determines that the vehicle is not starting and the control according to the map shown in FIG. 12 is not performed. That is, the duty ratio control of the chopper signal is performed only based on the map shown in FIG.

In the standard mode, the rear wheel motor 9
Is rotated, the controller 23 receives the total current It (in the standard mode, the current flowing through the rear wheel motor 9). The total current It is equal to the front and rear wheels OC.
When the value is larger than the L value L3, the comparator 67 outputs the second limit signal S2. As a result, the output of the chopper signal to the main transistor 28 is cut off by the AND circuit 70, and the main transistor 28 is protected.

Similarly, when the total current It is larger than the total current threshold L4 determined based on the map shown in FIG. 9, the comparator 74 outputs the third limit signal S3. As a result, the output of the chopper signal to the main transistor 28 is cut off by the AND circuit 70,
An optimal driving force according to the operation amount of the accelerator lever 12 is secured.

When the chopper signal is cut off, the total current It decreases, and the outputs of both limit signals S2 and S3 disappear, the chopper signal is output to the main transistor 28 again.

As described above, in both maps shown in FIGS. 9 and 10, the voltage applied to the rear wheel motor 9 in the standard mode, the rear wheel motor 9 in the slip start mode, and the left and right When the voltages applied to the front wheel motors 5L and 5R are the same, the voltages are constant (2V).
Below, the value of the total current threshold L6 according to the map in the slip start mode is higher than the value of the total current threshold L4 also according to the map in the standard mode. On the other hand, above the certain voltage, the opposite is true. The reason for such setting is as follows.

That is, in the standard mode, only the rear wheel motor 9 is driven to rotate, so that all the current It flows through the rear wheel motor 9, whereas in the slip start mode, the left and right front wheel motors 5L, 5R , And rear wheel motor 9
Are rotationally driven, the total current It is shunted to each motor. Therefore, if both the current thresholds L4 and L5 are equal to or less than the predetermined voltage, the motors 5L and 5L in the slip start mode are compared with those in the standard mode.
This is because the driving force of R and 9 decreases, and the driving force required for starting cannot be secured.

On the other hand, when the voltage is equal to or higher than the predetermined voltage, it is necessary to suppress the driving force in the slip starting mode to be lower than the driving force in the standard mode in order to prevent occurrence of slip due to excessive driving force and to achieve a smooth start. Because there is.

In the standard mode, the accelerator lever 12
Is operated from the forward direction to the reverse direction via the neutral position, the CPU 50 switches the rear wheel forward and rear wheel reverse contactors 26 and 27 to the reverse drive direction, and at the same time, the vehicle speed at that time is the regenerative braking speed. Is determined. As a result, when it is determined that the regenerative braking can be performed, the CPU 50 turns off the regenerative contactor 25.

When the regeneration contactor 25 is turned off, C
The PU 50 controls the main transistor 28 and the regenerating transistor 32 to perform a known pre-excitation, thereby increasing the electromotive force of the rear wheel motor 9 and generating a regenerative current. The regenerative current is the negative terminal of the battery 24, the regenerative diode 3
4. All current sensor 31, armature 9a, rear wheel reverse contactor 27 (in the case of switchback operation from reverse to forward, it becomes rear wheel forward contactor 26), field winding 9
b, and the flywheel diode 29 (in the case of a switchback operation from reverse to forward, it becomes a flywheel diode 30) to the + terminal of the battery 24.
Regenerated in

As described above, this regenerative current is detected by the all-current sensor 31, and the regenerative current value is output to the CPU 50. When the regenerative current becomes equal to or greater than a predetermined allowable current value, the CPU 50 controls the main transistor 28 by chopper control to suppress the regenerative current.

When the vehicle speed reaches a speed at which regenerative braking cannot be performed, the CPU 50 shifts to plugging braking. CP
U50 switches the rear wheels forward and rear wheels reverse contactors 26, 27 as the rear-wheel motors 9 are reverse drive, front wheels forward and the front wheel reverse contactors 42 and 43
Switch. The CPU 50 is provided with the regenerative contactor 2.
Turn 5 on. Then, the CPU 50 performs chopper control of the main transistor 28 at a duty ratio with respect to the operation amount S in the switchback operation of the accelerator lever 12 at that time. Accordingly, the rear wheel motor 9 rotates in the reverse direction to drive backward, and plugging braking is started.

In the slip start mode, when a similar switchback operation is performed, as described above, the CPU 50 controls to turn off the right front wheel and left front wheel motor contactors 40, 41. Later, the same control as in the standard mode operates.

In this embodiment, as described above, the left and right front wheel motors 5L, 5R,
Since the three wheels of the rear wheel motor 9 are driven, as in the related art, the three-wheel drive is always performed at the time of starting regardless of the occurrence of slip, but unnecessary power consumption of the battery 24 can be eliminated. The operating time can be extended. Similarly, early wear of the left and right front wheels 4L, 4R can be prevented.

Furthermore, even when the vehicle is starting, when no slip occurs, the rear wheel is driven, so that the current limitation by the front wheel motor is eliminated, and a high driving force can be obtained. Therefore, on a high μ road surface where slippage is unlikely to occur, starting on an uphill road and pushing operation at the time of starting can be easily performed.

Further, after a slip occurs at the time of starting,
Until the delay time until the contactors 41, 40 for the left and right front wheel motors are turned on, the drive of all the motors is stopped, and then the three-wheel drive is started. Also, even on a low μ road surface, the occurrence of slip is reliably prevented, and a smooth start can be performed.

Further, in the slip start mode, an appropriate duty control of the chopper signal with respect to the operation amount S of the accelerator lever 12 is performed according to the maps shown in FIG. 8 and FIG. This eliminates the need for the accelerator operation, and ensures the prevention of slipping even on a low μ road surface, enabling a smooth start.

Further, in the slip start mode, the total current It is limited in accordance with the map shown in FIG. 10, so that the driver does not need to have a skilled accelerator operation as described above.
Even on low μ road surfaces, reliably prevent the occurrence of slip,
You can start smoothly.

Further, only when the vehicle speed change rate exceeds the vehicle speed change rate threshold value L1 and the total current It falls below the total current threshold value L2 according to the map shown in FIG.
Since the occurrence of slip is determined, extremely accurate slip detection can be easily performed.

Further, the present invention can be easily realized by changing the control contents of the controller 23 without adding any new parts to the prior art, and is extremely low in cost.

[0164] In the present embodiment, as has been described above, when the slip occurs at the start, the control that switches to the slip start mode is forcibly made separately in the driver's seat W, on / off It is of course possible to provide a switch so that it is possible to select in advance whether to invalidate the control.

In this embodiment, the accelerator lever 1
2 is used, but the present invention is not limited to this, and for example, a pedal type may be used. Further, in the present embodiment, only the main transistor 28 is chopper-controlled. However, the present invention is not limited to this. For example, one transistor is provided for each of the left and right front wheel motors 5L and 5R and the rear wheel motor 9. A chopper control may be provided.

Of course, the other configurations described in this embodiment can be replaced with other configurations without departing from the gist.

[0167]

As described above, the present invention reliably prevents slippage of a reach-type forklift at the time of starting, and at the same time, prevents early abrasion of the front wheels and a decrease in operating time, and attains a high level at the time of starting. It is possible to provide a low-cost and high-performance reach-type forklift drive control device that prevents a decrease in driving force on a μ road surface and facilitates starting operation on an uphill road and pushing operation at the start. .

[Brief description of the drawings]

FIG. 1 is a side view of a reach type forklift according to the present invention.

FIG. 2 is a schematic top view of a reach type forklift according to the present invention.

FIG. 3 is a schematic top view of the reach type forklift according to the present invention.

FIG. 4 is a partial front view of a rear wheel portion of a reach-type forklift according to the present invention.

FIG. 5 is a circuit diagram of a drive control device for a reach type forklift according to the present invention.

FIG. 6 is a block diagram of a controller included in the drive control device for the reach-type forklift according to the present invention.

FIG. 7 is stored in a storage unit of the controller.
5 is a map for determining a target duty ratio of a chopper signal in a standard mode.

FIG. 8 is stored in a storage unit of the controller.
5 is a map for determining a target duty ratio of a chopper signal in a slip start mode.

FIG. 9 is stored in a storage unit of the controller.
4 is a map for determining a total current threshold value in a standard mode.

FIG. 10 is a map for determining a total current threshold value in a slip start mode, which is stored in a storage unit of the controller.

FIG. 11 is a map for determining a total current threshold value stored in a storage unit of the controller.

FIG. 12 is a map that is stored in a storage unit of the controller and that determines a ratio to a target duty ratio when the vehicle starts in the standard mode.

FIG. 13 is a map for determining a ratio to a target duty ratio in a slip start mode, stored in a storage unit of the controller.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2R ... Right leg, 2L ... Left leg, 4R ... Right front wheel, 4L ... Left front wheel, 5R ... Electric motor for right front wheel, 5L ...
Left front wheel electric motor, 6 ... Rear wheel rotation speed sensor, 7 ... Rear wheel, 9 ... Rear wheel electric motor, 12 ... Accelerator lever, 1
5: Drive control device, 23: Controller, 40: Contactor for right front wheel motor, 41: Contactor for left front wheel motor, 50: CPU, 63, 67, 74: Comparator, R: Rotation speed, S: Operation amount, It ... total current, If ... front wheel current,
M1: target duty ratio, M2: target duty ratio, L
1: vehicle speed change rate threshold, L2, L4, L6: total current threshold, L3: front and rear wheel OCL values, L5S, L5W ...
Front wheel OCL value, L7: Start end vehicle speed

Continuation of the front page (56) References JP-A-7-163020 (JP, A) JP-A-53-105046 (JP, A) JP-A-2-299402 (JP, A) JP-A-61-147707 (JP) , A) JP-A-1-222608 (JP, A) JP-A-54-33414 (JP, A) JP-A-2-137777 (JP, A) JP-A-5-162995 (JP, A) 55-110328 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60L 15/28 B60K 1/02 B66F 9/10 B66F 9/24

Claims (9)

(57) [Claims] 1. A leg provided on both left and right sides in front of a vehicle, a front wheel provided on the leg, an electric motor for a front wheel driving the front wheel, a rear wheel provided on a lower portion of the vehicle, and a wheel electric motor that drives rear wheels, the drive control device of the reach forklift comprising a steering device for steering the rear wheels, and means for opening and closing the energy supply path for operating the electric motor for the front wheel, the Means for detecting the speed of the vehicle, means for determining whether or not the vehicle is starting based on the speed detected by the means for detecting the speed of the vehicle, means for detecting slip of the vehicle, When it is determined that the vehicle is starting by the means for determining whether the vehicle is starting,
And when it is determined that the vehicle is slipping by the means for detecting vehicle slip, the energy supply path is opened and closed by the means for opening and closing the energy supply path for operating the front wheel electric motor, and the front wheels can be driven. Processing means for closing the energy supply path by the means for opening and closing the energy supply path and disabling the front wheels;
When it is determined that the vehicle is starting by the means for determining whether or not the vehicle is starting, and when it is determined that the vehicle is slipping by the means for detecting slip of the vehicle, the supply of energy for operating the rear wheel electric motor is stopped. After holding the state for a predetermined period of time , the electric motor for the front wheels and the electric
Processing means for starting supply of energy for operating the dynamic motor, wherein the predetermined time period is supplied to the means for opening and closing the energy supply path for operating the front wheel electric motor. A drive control device for a reach-type forklift, characterized in that a delay time from when the vehicle arrives to when the vehicle actually opens is set. 2. A leg provided on both left and right sides in front of the vehicle, a front wheel provided on the leg, an electric motor for a front wheel driving the front wheel, and a rear wheel provided on a lower portion of the vehicle. a wheel electric motor that drives rear wheels, the drive control device of the reach forklift comprising a steering device for steering the rear wheels, and means for opening and closing the energy supply path for operating the electric motor for the front wheel, the Means for detecting the speed of the vehicle, means for determining whether or not the vehicle is starting based on the speed detected by the means for detecting the speed of the vehicle, means for detecting slip of the vehicle, When it is determined that the vehicle is starting by the means for determining whether the vehicle is starting,
And when it is determined that the vehicle is slipping by the means for detecting slip, the means for opening and closing the energy supply path for operating the front wheel electric motor opens the energy supply path and enables the front wheels to be driven. Processing means for closing the energy supply path by the means for opening and closing the energy supply path and disabling the front wheels;
Means for opening and closing an energy supply path for operating the front wheel electric motor, and means for detecting a current flowing to the rear wheel electric motor when the energy supply path is closed and the front wheel cannot be driven. Wherein the means for detecting the speed of the vehicle includes means for detecting a rear wheel rotation speed, and processing means for calculating the vehicle speed from the rear wheel rotation speed detected by the means for detecting the rear wheel rotation speed. Wherein the means for detecting slip is calculated by a processing means for calculating a vehicle speed change rate from a vehicle speed calculated from the rear wheel rotation speed, and a processing means for calculating a vehicle speed change rate. a first discriminating means, the current detected by said means for detecting a current flowing through the electric motor for the rear wheels is pre to determine whether exceeds a first threshold vehicle speed change rate is provided in advance Second determining means for determining whether a second threshold value provided is exceeded, the first determining means exceeding the first threshold value, and the second determining means A drive unit for a reach-type forklift, comprising: processing means for determining occurrence of slip only when it is determined that the second threshold value is not exceeded. Wherein said means for detecting a slip, only the first threshold value, or both the said first threshold the second threshold, for the front wheel electric motor and the rear wheel The amount of operation of any one of the mechanism for adjusting the voltage applied to the electric motor or the mechanism for adjusting the rate of increase in voltage until the voltage adjusted by the mechanism is reached, and 3. The drive control device for a reach-type forklift according to claim 2, further comprising means for changing the operation amount in accordance with the operation amount based on a predetermined correlation with the threshold value. 4. A voltage applied to the electric motor for the front wheels electric motor and the rear wheels, the average voltage determined based on a duty ratio that is regulated by the chopper control, electric front wheel
The mechanism for adjusting the voltage applied to the dynamic motor and the rear wheel electric motor has an accelerator lever, and means for varying the duty ratio according to the operation amount of the lever,
The mechanism for adjusting the rate of increase in voltage until reaching the voltage adjusted by the mechanism for adjusting the voltage applied to the front wheel electric motor and the rear wheel electric motor is at least two or more types of preset, Means for selecting one of the time-dependent increase patterns of the duty ratio until the duty ratio corresponding to the operation amount of the lever is reached, and the means for determining whether the vehicle is starting or not, when starting. Processing means for increasing the duty ratio over time in accordance with the duty ratio increasing pattern selected by the means for selecting the duty ratio increasing pattern only when it is determined. 4. The drive control device for a reach type forklift according to claim 3. 5. The method according to claim 1, wherein the means for opening and closing the energy supply path for operating the electric motor for the front wheel is closed when the energy supply path is closed and the front wheel cannot be driven.
Means for determining whether the current detected by the means for detecting the current flowing in the electric motor exceeds a third threshold value set in advance, and detecting the current flowing in the rear wheel electric motor. The current detected by the means is:
Means for judging whether or not a fourth threshold value, which is variable based on a predetermined fixed correlation with the voltage applied to the rear wheel electric motor, has been exceeded; If it is determined that at least at least one of the thresholds is exceeded, the voltage applied to the front wheel electric motor and the rear wheel electric motor is adjusted until the current falls below both the thresholds. When the energy supply path is opened and the front wheels can be driven by the processing means for stopping the voltage and the means for opening and closing the energy supply path for operating the front wheel electric motor in preference to the operation amount of the mechanism, , power for the front wheel
Means for detecting a current flowing in the dynamic motor, and means for detecting the total current flowing in both the electric motor for an electric <br/> motor and rear wheel front wheel, the current flowing through the front wheel electric motor current detected by said means for detecting is set beforehand, and means for determining whether exceeds the fifth threshold value lower than said third threshold, after a front wheel electric motor and means for determining whether the current detected by the means for detecting the total current flowing in both wheel electric motor, it exceeds the said third preset threshold, electric front wheel
Current detected by said means for detecting the total current flowing in both dynamic motor and the rear wheel electric motor, in advance between the voltage applied to the front wheel electric motor <br/> motor and the rear wheel electric motor Means for determining whether or not a sixth threshold that varies based on the set constant correlation is determined, and at least one of the three means for determining whether the current exceeds the threshold, If it is determined that exceeds, said current until below the threshold, in preference to the amount of operation of said mechanism for adjusting the voltage applied to the electric motor for the front wheels electric motor and the rear wheels, to stop the voltage 5. The drive control device for a reach type forklift according to claim 2, further comprising a processing unit. 6. When the energy supply path for opening and closing the energy supply path for operating the front wheel electric motor is opened and the front wheel is drivable, the front wheel
The rate of increase of the voltage to reach the voltage that is regulated by the mechanism for adjusting the voltage applied to the electric motor and the rear wheel electric motor, in preference to the operation amount of the mechanisms regulating the rate of increase, in advance 6. The drive control device for a reach type forklift according to claim 3, further comprising processing means for following the provided time-increasing pattern. When 7. A front opening energy supply path can be driven, which can be adjusted by the mechanism for adjusting the voltage applied to the front wheel electric motor and the rear wheel electric motor <br/> over data 5. The method according to claim 3, further comprising means for lowering the maximum voltage below the maximum voltage when the energy supply path is closed and the front wheels cannot be driven. 7. The drive control device for a reach type forklift according to claim 6. 8. A voltage front wheel is applied to the wheel electric motor after a time of non-drivable, the voltage front wheel is applied to the front wheel electric <br/> motor motor and the rear wheels when the drivable When the voltages are the same, the sixth threshold value is set lower than the fourth threshold value when both voltages are equal to or more than a predetermined value, and the sixth threshold value is set when both voltages are equal to or less than a certain value. 7. The method according to claim 5, wherein the threshold value is set higher than the fourth threshold value.
A drive control device for a reach-type forklift according to claim 7. 9. A discriminating means for discriminating whether or not the speed detected by the means for detecting the speed of the vehicle has exceeded a seventh threshold value provided in advance. Processing means for closing the energy supply path by the means for opening and closing the energy supply path for operating the front wheel electric motor when it is determined that the seventh threshold value is exceeded, and disabling the front wheel; 9. A processing device according to claim 1, further comprising processing means for keeping the energy supply path closed even when the energy supply path drops again after exceeding the threshold value. A drive control device for the reach-type forklift described in the above.