JPH11122721A - Reach fork lift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reach fork lift wherein the two-wheel drive of its front and rear wheels can be utilized effectively responding to its operational situation. SOLUTION: A reach fork lift has a first controller 51 for controlling the rotational direction and speed of rear wheels 13; and a second controller 53 for controlling the respective rotational directions and speeds of auxiliary motors 15, 16 of its front wheels 11, 12, based on the polarity and magnitude of a deviation signal e, between a rear-wheel speed specifying signal 56 obtained in the first controller 51 with respect to the rotational direction and speed of the rear wheels 13, and a feedback signal 57 obtained on the basis of the sensings of the respective rotational directions and speeds of the front wheels 11, 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reach forklift for driving a front wheel in addition to an original rear wheel drive.

[0002]

2. Description of the Related Art An outline of a reach forklift 1 of this type is shown in FIG. FIG. 4A is a side view, and FIG. 4B is a top view. In the figure, a pair of left and right legs 3 and 4 are formed to extend in front of a vehicle body 2, and the legs 3 and 4 are formed.
A mast 5 that can be moved in the front-rear direction is disposed between them. A fork 6 is arranged on the matos 5 so as to be vertically movable.

A left front wheel 11 and a right front wheel 12 are provided at the tips of a pair of left and right legs 2 and 3. A rear wheel 13 is provided on a lower left side of the vehicle body 2, and a caster wheel 14 is provided on a lower right side of the vehicle body 2. The rear wheel 13 can be steered by the steering wheel 7 and is connected via a reduction gear to a drive motor that generates a driving force according to the operation amount of the accelerator lever 8.

[0004] In such a reach forklift 1, when the lift 5 is advanced forward and luggage is placed on the fork 6, the center of gravity moves from the vehicle body 2 to the legs 2 and 3 to serve as drive wheels. The load acting on the rear wheel 13 decreases. In such a state, the rear wheel 13 may slip even when the reach fork foot 1 is run or started on a road surface having a low friction coefficient, for example, a slippery road surface in a freezer.

Therefore, not only the rear wheel 13 at the lower portion of the vehicle body 2 but also the front wheels 1 provided at the tips of the legs 3 and 4 are provided.
Auxiliary driving of the motors 1 and 12 is performed. However, if the front wheels 11, 12 are constantly driven, the front wheels 11, 12
Is configured like a two-wheel speed difference steering control system, and competition occurs with the steering rear wheel 13, thereby impairing the operability of the reach forklift 1 that can make a small turn. Therefore, the slip at the time of the start of the reach forklift 1 is detected by the difference between the speed of the rear wheel and the speed of the front wheel, and only when the slip is detected, the front wheels 11 and 12 are driven auxiliary to escape from the slip. Easy things have been done.

[0006]

However, the front wheels 11, 12 are driven only when it is detected that the rear wheel 13, which is the driving wheel, has slipped, so that the front wheels 11, 12 are driven.
However, there is a problem that the drive mechanism of the above is not effectively utilized.

Accordingly, the present invention is to assist the front wheels to easily escape from the slip when the rear wheels, which are the driving wheels, slip, and to adjust the rear wheels and the front wheels according to the driving condition of the vehicle. An object is to provide a reach forklift capable of effectively utilizing two-wheel drive.

[0008]

According to a first aspect of the present invention, there is provided a rear wheel provided at a lower portion of a vehicle body and connected to a main motor for driving the vehicle.
A first wheel provided on each of a pair of left and right legs formed to extend forward of the vehicle and connected to an auxiliary motor for assisting traveling of the vehicle; and a first wheel for controlling a rotation direction and a rotation speed of the rear wheel.
A controller, a rear wheel speed command signal related to the rotation direction and rotation speed of the rear wheel in the first controller, and a magnitude of a deviation signal between a feedback signal based on detection of the rotation direction and speed of the front wheel and a magnitude of a deviation signal. And a second controller for controlling the rotation direction and the number of rotations of the auxiliary motor.

According to a second aspect of the present invention, in the first aspect, the second controller obtains a vehicle speed corresponding to the rear wheel speed command signal, and the deviation signal is near zero in a predetermined range. In this case, the front wheel is set free without driving the auxiliary motor.

According to a third aspect of the present invention, in the first or second aspect, the second controller obtains a vehicle speed according to the rear wheel speed command signal when the rear wheel slips when the vehicle is moving forward or backward. Instead, the deviation signal increases in either the positive or negative direction, and the front wheels are driven in the same direction as the rear wheels to assist in slipping out.When the vehicle stops moving forward or reverse, the rear wheels slip. The vehicle travels even though the rear wheel speed command signal is zero, the deviation signal is output in either a negative or positive direction, drives the front wheels in a vehicle stop direction, and the rear wheels when climbing a hill. When the vehicle starts to decelerate or reverse, the vehicle speed according to the rear wheel speed command signal is not obtained,
When the deviation signal increases in the positive direction, the front wheels are driven in the direction of ascending the hill to assist in ascending the hill, and when the accelerator of the rear wheel is loosened or the brake is applied when descending the hill, the rear wheel speed command signal is output. Is small or zero, the vehicle runs faster, the deviation signal increases in the negative direction, and the front wheels are driven in the opposite direction to the rear wheels.

According to a third aspect of the present invention, in the first, second or third aspect, the auxiliary motor is a wheel-in motor built in a wheel and directly driving the wheel.

[0012]

Embodiments of the present invention will be described with reference to the drawings. Since the overall structure of the reach forklift according to the present invention is the same as that described with reference to FIG. 4, the description of FIG.

The parts to be described in addition to FIG. 4 are the form of connection between the front wheel and its motor shown in FIG. 2 and the drive mechanism for the rear wheel shown in FIG.

In FIG. 2, an inner race 22 is fitted into a fixed shaft 21 on the leg side, an outer race 24 is rotatable with respect to the inner race 22 via a bearing 23, and a rubber wheel is baked on the outer periphery of the outer race 24. 25 constitute the front wheels 11 and 12. Auxiliary motor 1 for front wheels 11 and 12
Reference numerals 5 and 16 denote a stator core 26 on the inner ring 22 side and the outer ring 2
This is a high-density (high-density) motor comprising a rotor core 28 in which a permanent magnet 27 is inserted into a 4-side iron core.

The auxiliary motors 15 and 16 are wheel-in motors built in the front wheels 11 and 12,
Are directly driven (direct drive) by the auxiliary motors 15 and 16 without passing through a speed reducer. Auxiliary motor 15,
The reference numeral 16 is a magnetic circuit which always causes the permanent magnet to act in a dynamic manner, and is compact and can generate a large torque at a low speed, so that it can be a direct drive.

The front wheels 11 and 12 and the auxiliary motor 1
Due to the connection form of the 5, 16 wheel-in motors and direct drive, there is almost no mechanical loss due to rotation as compared with the drive via the speed reducer, the attachment to the leg is free, and the maintenance is free. Particularly when there is no auxiliary driving, there is an advantage that the motor rotates freely like a normal driven wheel. That is, it can be said that it is normally used as a driven wheel, and is driven supplementarily only when necessary.

In FIG. 3, a rear wheel 13 is provided with a main motor 17
Of the gear box 31 coaxially arranged on the output shaft of the gear box 31. A motor shaft 33 is protrudingly provided on the side opposite to the output shaft of the main motor, and the brake disc 3 fitted into the motor shaft 33 is provided.
A brake pad 35 is provided on the outer periphery of the brake pad 4. When the command from the brake release switch described later turns off,
The brake pad 35 is closed to provide a deadman brake that sandwiches the brake disc 34. The brake device is not limited to a mechanical brake for the rear wheel 13, but may be an electric brake such as a plugging brake or a regenerative brake.

FIG. 1 is a circuit diagram of the drive control including the front wheels 11 and 12 and the auxiliary motors 15 and 16 having the excellent characteristics described above.

In FIG. 1, a vehicle drive control circuit includes a first
The controller 51, the main motor drive circuit 52, the second controller 53, and the auxiliary motor drive circuit 54 are configured as main parts.

In the main motor drive circuit section 52, the main motor 17 is connected to the battery power supply 5 via a powering contactor 61.
5 is connected. The main motor 17 is a series-wound DC motor composed of an armature 17a and a field winding 17b. A forward contactor 62 and a reverse contactor 63 are connected to the field winding 17b. Both contactors 62, 63
When the direction of the field current flowing through the field winding 17b is changed by the complementary switching operation of the above, the main motor 17 rotates forward and backward.

The main transistor 64 has an anode connected to the forward contactor 62 and the reverse contactor 63 of the field winding 17b, and an emitter connected to the ground, so that the main transistor 64 is connected in series to the main motor 17. It is connected. Then, the first controller 51 is connected to the base terminal.
A known chopper (intermittent) signal is input. Here, 65a is a commutation diode, 65b is an anti-brake diode, 65c is a regenerative diode, and 85 is a tachometer for detecting the rotation speed of the rear wheel 13.

A command value corresponding to the operation amount is input from the accelerator 8 to the first controller 51, and a forward switch 67 and a reverse switch 68 are also connected. When the command value of the accelerator 8 is input to the first controller 51, the transistor switch 69 for operating the powering contactor 61 is closed. When the forward switch 67 or the reverse switch 68 is turned on, the transistor switch 70 for operating the forward contactor 62 and the transistor switch 71 for operating the reverse contactor 63 are complementarily switched. When the brake pedal (not shown) is released, the brake release switch 72 is turned off, and the brake pad 35 shown in FIG. 3 is closed to apply a brake. The off signal of the brake release switch 72 is output to the first controller 51. . The rotation speed of the armature 17 a of the main motor 17 is detected by the tachometer 73 and output to the first controller 51. The forward switch 67, the reverse switch 68, and the like constitute the forward / reverse command means, and the brake release switch 72 constitutes the brake command means.

In the auxiliary motor drive circuit section 54, the auxiliary motors 15, 16 are high-density motors as described with reference to FIG. 2, and are driven by drivers 75, 76 which operate according to command values from the second controller 53. .

The second controller 53 uses a rear wheel speed command 56 from the first controller 51 as a command signal and a front wheel tachometer speed signal based on detection of the rotation direction and speed of the front wheel as a feedback signal 57. It is.

The rear wheel speed command 56 is a command determined by the rotation direction of the rear wheel 13 which is determined by the direction in which the accelerator 8 is tilted forward or backward, and the number of rotations determined by the degree to which the accelerator 8 is tilted.
When the rotation speed increases in the forward direction, a large command value is output proportionally in the positive direction, and when the rotation speed increases in the reverse direction, a large command value is output proportionally in the negative direction.

The feedback signal 57 of the front wheel tachometer speed signal is supplied to a tachometer 73, 74 for each of the front wheels 11, 12, an adder 78 for obtaining the sum of the outputs of the tachometers 73, 74, and an adder 7
When the actual traveling speed of the front wheels 11 and 12 is large in the forward direction, a large signal value is output in the positive direction in proportion to the output of a device comprising a computing unit 79 that halves the output from the output unit 8. When the actual traveling speed of the front wheels 11 and 12 increases in the reverse direction, a large signal value is output in the negative direction in proportion.

The second controller 53 has a rear wheel speed command 5
6, an arithmetic unit 79 for obtaining the deviation signal e by subtracting the feedback signal 57, a comparator 80 for the deviation signal e, and a regulator 8
It consists of 1. The comparator 80 outputs an OFF signal to the interrupter 57 when the deviation signal e is smaller than a predetermined range sandwiching zero, and outputs an ON signal to the interrupter 57 when the deviation signal exceeds the predetermined range. is there. When the interrupter 57 is turned off, the battery power supply 55 for the auxiliary motors 15 and 16 is turned off.
Is disconnected, and the front wheels 11, 12 rotate freely.
When the interrupter 57 is turned on, the electric power of the battery power supply 55 is supplied to the auxiliary motors 15 and 16, and the front wheels 11 and 12 are controlled and driven based on the output from the adjuster 81. When the deviation signal e is large in the positive direction, the controller 81
When the deviation signal e is large in the negative direction, the front wheels 11, 12 are driven in the same direction as the rear wheels 13.
Is driven at a rotational speed proportional to the rear wheel 13 in the reverse direction.

Next, an example of the operation of the vehicle drive control circuit shown in FIG. 1 will be described separately when starting forward or backward, when stopping forward or backward, when ascending a slope, and when descending a slope.

First, a description will be given of a sudden start of forward or backward travel. For example, when the forward switch 67 is turned on and a command value corresponding to the operation amount of the accelerator 8 is input to the first controller 51, the powering contactor 61 is closed by the transistor switch 69, and the forward / backward contactors 62, 63 by the transistor switches 70, 71. Are switched in a complementary manner, and the current corresponding to the accelerator operation amount flows to the main motor by the chopper signal to the main transistor 64, and the rear wheels are driven in the forward direction by the power running force corresponding to the accelerator operation amount. You. Then, the first controller 51
Outputs a forward direction corresponding to the accelerator operation amount, that is, a positive rear wheel speed command 56 to the second controller 53.

At this time, since the front wheels 11 and 12 are direct drives, they normally function as free driven wheels.
Rotate without slipping. However, the rear wheel 13 is a drive wheel and tends to slip when the center of gravity moves forward. When the rear wheel 13 slips, the vehicle does not start, and the feedback signal 57 based on the front wheel tachometer speed signal remains zero. Then, a positive deviation signal e having a magnitude corresponding to the accelerator operation amount is output from the calculator 79 to the adjuster 81, and the front wheels 11, 12 are driven by the drivers 75, 76 and the auxiliary motor 15 according to the magnitude of the deviation signal e. , 16 to assist the rear wheel 13 to escape from the slip state. When the slip of the rear wheel 13 is eliminated, the vehicle travels in accordance with the rear wheel speed command 56, so that it coincides with the feedback signal 57 based on the front wheel tachometer speed signal, and the deviation signal e becomes close to zero. Thus, the front wheels 11, 12 return to the original driven wheels.

The comparator 80 takes into account the delay of the entire system. There is a delay between the accelerator and the vehicle speed, and the vehicle speed detected by the front wheels 11, 12, that is, the front wheel speed signal 57 is the rear wheel speed command 57 of the first controller 51.
This is because it is not preferable to immediately change the front wheels 11 and 12 from free to driving just because they do not match. If a slip occurs on the rear wheels when the vehicle starts moving backward, the positive / negative relationship between the rear wheel speed command 56, the feedback signal 57, and the deviation signal e is reversed, and the same operation is performed only when the vehicle moves forward in reverse. .

Next, a description will be given of the case of a sudden stop during forward or reverse travel. For example, when a sudden stop operation is performed to depress the brake pedal during forward movement, the brake release switch 72 is turned on, the brake pad 35 in FIG. 3 is closed and the rear wheel 13 is locked, and the rear wheel is regardless of the operation amount of the accelerator 8. The speed command 56 becomes zero. However, if the center of gravity moves toward the front wheels 11 and 12, the slip may occur with the rear wheels 13 locked, and the vehicle may travel due to inertia. Front wheel 11,1
2 rotates in the forward direction, the feedback signal 57 based on the front wheel tachometer speed signal becomes a negative output, and the rear wheel speed command 56
Is zero, the deviation signal e has a negative output. The controller 81 controls the front wheels 11 and based on the magnitude of the negative deviation signal e.
Reference numeral 12 is driven in the reverse direction via drivers 75 and 76 and auxiliary motors 15 and 16 to prevent the vehicle from running by inertia and assist in a sudden stop.

When the vehicle travels due to inertia at the time of sudden reverse stop, the positive / negative relationship between the feedback signal 57 and the deviation signal e is reversed while the rear wheel speed command 56 remains zero, and the front wheel 1
1 and 12 are driven in the forward direction to assist the sudden stop in the reverse direction of the vehicle.

Next, a description will be given of when the vehicle goes up a slope. If the degree of the slope is small and the vehicle speed according to the rear wheel speed command 56 is obtained, the deviation signal e between the rear wheel speed command 56 and the feedback signal 57 based on the front wheel tachometer speed signal is close to zero. , The front wheels 11, 12 remain free driven wheels.

When the load on the vehicle increases when the uphill slope becomes steep, the vehicle speed cannot be obtained according to the rear wheel speed command 56, and the vehicle starts to decelerate. The driver of the vehicle operates the accelerator 8 in the forward direction to maintain the speed of the vehicle.
Then, while the rear wheel speed command 56 further increases, the feedback signal 57 decreases, and a positive deviation signal e is output. When the positive deviation signal e becomes larger than a predetermined value of the comparator 80, the controller 81 controls the front wheels 11, 12 by the drivers 75, 76 and the auxiliary motor 15,
The vehicle is driven in the forward direction through the line 16 to assist the vehicle in climbing a hill.

When the vehicle is stopped and the vehicle starts moving backward even if the accelerator 8 is operated to the maximum in the forward direction, the rear wheel speed command 56 remains at the maximum. The positive and negative of the signal 57 are reversed and become a positive output. Then, the deviation signal e becomes the wheel speed command 56 + the feedback signal 57 and increases in the positive direction. Based on the increased deviation signal e, the front wheels 11 and 12 are driven via the drivers 75 and 76 and the auxiliary motors 15 and 16. It is further strongly driven in the forward direction to prevent the vehicle from going backward on a slope.

Next, a description will be given of when the vehicle descends on a slope. If the degree of the slope is small and the vehicle speed according to the rear wheel speed command 56 is obtained, the deviation signal e between the rear wheel speed command 56 and the feedback signal 57 based on the front wheel tachometer speed signal is close to zero. The front wheels 11 and 12 remain free driven wheels in the same manner as when climbing a hill.

When the descending slope of the slope becomes steep, the vehicle speed cannot be obtained according to the rear wheel speed command 56, and the vehicle starts to accelerate. The driver returns the accelerator 8 toward the neutral position according to the speed of the vehicle, and applies the brake. But,
If the descending gradient is steep, the vehicle starts accelerating even if the accelerator 8 is returned to the neutral position, and the feedback signal 57 based on the front wheel tachometer speed signal has a negative value even though the rear wheel speed command 56 is zero. And the deviation signal e takes a negative value. Then, based on the negative deviation signal e, the front wheels 11 and 12 drive the driver 75,
The vehicle is driven in the direction of ascending on the sloping road via the auxiliary motors 76 and the auxiliary motors 15 and 16 to prevent the vehicle from accelerating when descending the sloping road.
Of course, the acceleration of the vehicle at the time of descending the slope is caused by the front wheels 11 and 12.
If the vehicle cannot be stopped by the auxiliary driving, the driver operates the brake pedal, and the mechanical braking force of the rear wheel 13 is also applied.

[0039]

According to the first aspect of the present invention, the speed control by the rear wheel speed command signal relating to the rotation direction and the rotation speed of the rear wheel and the feedback signal based on the detection of the rotation direction and the speed of the front wheel. By using the system, the front wheels are free during normal running of the vehicle and the small turning of the vehicle is secured, and the front wheels are automatically used as auxiliary drive except during normal driving of the vehicle such as when slipping Can be.

According to the second aspect of the present invention, it is possible to clarify the distinction between normal driving and other driving, and to automatically use the front wheels as auxiliary driving only in special cases such as slipping. it can.

According to the third aspect of the present invention, in all cases other than normal driving, such as driving assistance when suddenly starting or stopping when traveling forward and backward, and driving assistance when traveling uphill or descending a hill,
The front wheels can be used as an auxiliary drive.

According to the fourth aspect of the present invention, the front wheels are driven by a direct drive wheel-in motor, so that they function as driven wheels during normal running, but function as auxiliary driving wheels except during normal running. This mechanism is easy to use properly.

[Brief description of the drawings]

FIG. 1 is a control block diagram of a reach forklift according to the present invention.

FIG. 2 is a sectional view of a front wheel by a wheel-in type motor.

FIG. 3 is a top view showing a drive unit for a rear wheel.

FIG. 4 is an outline view of a reach forklift.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reach forklift 11 Left front wheel 12 Right front wheel 13 Rear wheel 15 Left front wheel auxiliary motor 16 Right front wheel auxiliary motor 17 Main motor 51 First controller 52 Main motor drive circuit 53 Second controller 54 Auxiliary motor drive circuit 56 Rear wheel Speed command 57 feedback signal (front wheel speed signal) e deviation signal 67 forward switch 68 reverse switch 72 brake release switch 73 tachometer 74 tachometer 26 stator core (wheel-in motor) 27 permanent magnet (wheel-in motor) 28 rotor core (wheel-in motor) ) 34 Brake disc (brake device) 35 Brake pad (brake device)

Claims (4)

[Claims] A rear wheel connected to a main motor for driving the vehicle, provided on a lower portion of the vehicle body, and provided on each of a pair of left and right legs formed to extend in front of the vehicle; A front wheel connected to an auxiliary motor that assists the vehicle, a first controller that controls the rotation direction and rotation speed of the rear wheel, and a rear wheel speed command signal related to the rotation direction and rotation speed of the rear wheel in the first controller. And a second controller for controlling the rotation direction and the number of rotations of the auxiliary motor based on the sign and magnitude of a deviation signal between a rotation direction and a feedback signal based on detection of a speed of the front wheel. 2. The second controller does not drive the auxiliary motor when a vehicle speed corresponding to the rear wheel speed command signal is obtained and the deviation signal is close to zero in a predetermined range. The reach forklift according to claim 1, wherein the front wheel is made free. 3. The second controller according to claim 1, wherein the rear wheel slips when the vehicle starts moving forward or backward, a vehicle speed corresponding to the rear wheel speed command signal is not obtained, and the deviation signal is either positive or negative. The front wheel is driven in the same direction as the rear wheel to assist in slip escape, and the rear wheel slips when the vehicle stops moving forward or backward, and the rear wheel speed command signal is zero. When the vehicle is running and the deviation signal is output in either a negative or positive direction, the front wheels are driven in a vehicle stop direction, and when the rear wheels start to decelerate or reverse when climbing a hill, the rear wheel speed command is issued. The vehicle speed cannot be obtained according to the signal,
When the deviation signal increases in the positive direction, the front wheels are driven in the direction of ascending the hill to assist in ascending the hill, and when the accelerator of the rear wheel is loosened or the brake is applied when descending the hill, the rear wheel speed command signal is output. The reach forklift according to claim 1 or 2, wherein the vehicle travels quickly even though is small or zero, and the deviation signal becomes large in the negative direction to drive the front wheels in the opposite direction to the rear wheels. 4. The vehicle according to claim 1, wherein the auxiliary motor is a wheel-in motor built in a wheel and directly driving the wheel.
The reach fork according to 2 or 3.