JPH11116200A - Reach type forklift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the driving performance. SOLUTION: A reach type forklift is structured so that the first drive wheel 4 capable of being rotated by the first motor and being steered from a steering wheel 3 is installed on the vehicle body part 2 and that rotatable load wheels 6L and 6R are mounted on a left 5L and a right straddle arm 5R protruding from the vehicle body part, wherein the second drive wheel 7 capable of being rotated by the second motor and being steered freely is installed on the body part 2, and a control device steers the second drive wheel 7 in such a direction that the extension line C2 of its rotary shaft intersects the center of revolution P which is decided by the first drive wheel 4 and the left and right load wheels 6L and 6R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reach type forklift capable of improving driving performance.

[0002]

2. Description of the Related Art As shown in FIG. 4, a reach type forklift f has a drive hole b which can be rotationally driven by an electric motor behind a vehicle body a, and a running stabilization fork. And a rotatable road wheel e at the tips of the left and right straddle arms d projecting from the vehicle body a.
It has. In addition, reach-type forklift f
Is provided with a fork g capable of loading a load, and a mast device equipped with the fork g is provided so as to be movable back and forth.

When a load is loaded on the fork g and the mast device h is moved forward, the center of gravity of the vehicle moves forward, so that the axle load of the drive wheel b is reduced. In addition, the workability is reduced, and in a severe case, the user may get stuck on the spot. Further, for example, even on a road surface having a low friction coefficient such as a freezer or a refrigerated warehouse, there is a problem that a slip occurs in the drive wheel b and the workability is reduced.

Conventionally, as a means for preventing this kind of slip, an electrical control method for detecting the slip state from the number of rotations of the drive wheel b and reducing the number of rotations of an electric motor for driving the drive wheel b is disclosed in, 252728
As disclosed in Japanese Patent Laid-Open Publication No. 6-2006, it has been proposed to provide an auxiliary motor capable of driving the left and right road wheels e in the straddle arm d to improve the driving performance as a so-called three-wheel drive.

[0005] However, in the former, slip can be suppressed to some extent, but its effect is still not enough, and the running response is deteriorated, so that the workability tends to be reduced. In the latter method, the electric motor must be incorporated within a very limited narrow dimension called a straddle arm, which makes it difficult to mount the electric motor and is not suitable for practical use.

The present invention has been devised in view of such a problem, and based on the fact that two drive wheels are provided in a vehicle body, these drive wheels are arranged around one turning center point. It is an object of the present invention to provide a reach-type forklift capable of improving driving performance and effectively suppressing slip by controlling the vehicle to turn.

[0007]

According to a first aspect of the present invention, there is provided a vehicle body having a first drive hole rotatable by a first electric motor and steerable by operating a steering wheel. A reach-type forklift including a rotatable road wheel on left and right straddle arms protruding from a vehicle body, wherein a steerable second drive wheel rotatable by a second electric motor is provided on the vehicle body. And a control device for steering the second drive wheel in a direction in which an extension of the rotation axis intersects a turning center point P defined by the first drive wheel and the left and right road wheels. Features.

According to a second aspect of the present invention, the control device includes a first steering angle detecting means for detecting a steering angle θ1 of the first drive wheel, and a steering device for steering the second drive wheel. An electric motor, a motor drive unit for controlling the driving of the electric motor for steering, and a target steering angle θ2A at which an extension of the rotation axis of the second drive wheel intersects the turning center point P based on the steering angle θ1. 2. The reach-type forklift according to claim 1, further comprising: an arithmetic processing unit that outputs a drive signal for steering the second drive wheel to the target steering angle θ2A to the motor drive unit.

According to a third aspect of the present invention, the control device controls the driving of the first electric motor at a rotation speed V1 proportional to the operation amount S of the accelerator device, and controls the first electric motor from the turning center point P to the first and the second motors. The reach-type forklift according to claim 2, wherein when the turning radii to the second drive wheel are L1 and L2, the rotation speed V2 of the second electric motor is drive-controlled at V1 / L2 / L1. It is.

According to a fourth aspect of the present invention, the first and second drive wheels are attached by first and second wheel supports, and the first and second wheel supports are attached in the direction of the vehicle center line. 4. The joint according to claim 1, wherein the first drive wheel and the second drive wheel are displaced up and down in a seesaw shape by a link body that swings around a horizontal axis. 5. It is a reach type forklift.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, the reach type forklift R of the present embodiment
Road wheels 6L, 6 having a first drive hole 4 rotatable by the electric motor M1 and steerable by operating the handle 3, and rotatable by left and right straddle arms 5L, 5R protruding from the vehicle body 2.
It has R.

Although not shown, the reach type forklift R is provided with left and right straddle arms 5 as in the prior art.
A mast device having a fork is provided between L and 5R so as to be able to move back and forth. The vehicle body 2 is provided with an accelerator device 13 (shown in FIG. 3) that can issue a command for the rotation drive direction and rotation speed of the first drive wheel 4.

The left and right road wheels 6L, 6R are
In this example, the vehicle is mounted so as not to be steerable in a state parallel to the straight traveling direction. In the present embodiment, the first drive wheel 4 is provided at a position deviated to the left of the vehicle body center line CL of the vehicle body 2. This first drive wheel 4
As shown in FIG. 2 where the vehicle body is viewed from the rear,
Attached to the wheel support 16.

The first wheel support 16 has a first
And a support ring body 16B that rotatably supports the turning gear case 16A, which pivotally supports the drive wheel 4 and has a gear for power transmission built therein. A ring gear G is fixed to the turning gear case 16A,
A gear (not shown) of a steering linkage linked to the handle 3 meshes with the ring gear G. As a result, the first drive wheel 4 is turned by the operation of the handle 3 together with the turning gear case 16A. At this time, the first drive wheel 4
Is an intermediate position D1 in the width direction and the circumferential direction of the wheel.
(As shown in FIG. 1).

In the present invention, the vehicle body 2
One of the features is that a steerable second drive wheel 7 that can be rotationally driven by the second electric motor M2 is provided.

As described above, in the present invention, in addition to the first drive wheel 4, the second drive wheel 7, which can be driven to rotate and is steerable, is provided on the vehicle body 2.
As a result, the driving force and the contact area of the driving wheel can be greatly expanded.As a result, even when the center of gravity changes due to loading of loads or on slippery road surfaces, it is possible to effectively suppress the occurrence of slip and start, run, and turn. The workability can be prevented from lowering. Further, since the vehicle body 2 can secure a design space wider than the straddle arm, it becomes practical.

As shown in FIG. 1, in the present embodiment, the second drive wheel 7 is located adjacent to the first drive wheel 4 in the width direction of the vehicle body and is located at a position close to the vehicle body center line CL of the vehicle body 2. Is also provided at a position deviated to the right, and in this example, the one provided at a position substantially symmetrical with the first drive wheel 4 with respect to the vehicle body center line CL is illustrated.
As a result, the left and right stability of the vehicle body is maintained, so that the conventional caster wheels are not provided. Further, the second drive wheel 7 is attached to a second wheel support 17 as shown in FIG.

The second wheel support 17 has a first
Similarly to the wheel support 16 of this embodiment, a turning gear case 17A pivotally supporting the second drive wheel 7 and internally incorporating a power transmission gear therein, and the turning gear case 17A
And a support ring body 17B that rotatably supports the support ring 17B. In addition, the turning gear case 17B includes:
In this example, the pinion gear of the steering motor 14 is configured to mesh.

Accordingly, by driving the steering motor 14, the turning gear case 17A can turn with respect to the support ring body 17B. In this embodiment, the second drive wheel 7 is moved in the width direction and the circumferential direction of the wheel. The intermediate position D2 (shown in FIG. 1) can be turned as the steering center point.

In this embodiment, the support ring bodies 16B of the first and second wheel supports 16, 17 are provided.
17B is connected to the fixing member 24 of the vehicle body 2 via the first to third link bodies 21 to 23.

As shown in FIG. 2, one end of the first link body 21 is rotatably connected to the support ring body 16B of the first wheel support 16, and the other end is rotatably connected to the fixing member 24. Connect and terminate. The second link body 22 has one end rotatably connected to the support ring body 17B of the second wheel support 17, and the other end rotatably connected to the fixing member 24, and terminates. Further, the third link body 23 has a substantially middle portion that is fixed to the fixing member 24.
A pin 2 whose axis center line is horizontal and extends in the direction of the vehicle center line.
5, one end is rotatably connected to the support ring body 16B of the first wheel support 16, and the other end is rotatably connected to the support ring body 17B of the second wheel support 17. Are linked.

By displacing the first and second wheel supports 16 and 17 and thus the first drive wheel 4 and the second drive wheel 7 up and down in a so-called seesaw shape, the driving wheels The ability to follow the road surface can be improved, the occurrence of slip can be suppressed, and the impact received from the unevenness of the road surface can be appropriately absorbed, so that the riding comfort can be greatly improved. Further, in the present embodiment, since the caster wheels are not provided as in the related art, there is no resistance due to the reversing force for reversing the caster wheels, such as when turning the vehicle forward and backward, and the slip at the time of starting is further suppressed. Help.

In this embodiment, each wheel support 16,
By providing a pressing means 26 capable of pressing each wheel toward the road surface on the 17 support ring portions 16B, 17B, a downward biasing force can be applied from the vehicle body 2. This can help to suppress large vertical displacement of the first and second drive wheels 4 and 7.
Although the pressing means 26 is formed of a spring in this example, various actuators such as a cylinder may be employed.

The reach-type forklift R of this embodiment is
As shown in FIG. 1, the second drive wheel 7 is
A control device 10 is provided for steering in such a direction that an extension line C2 of the rotation axis crosses a turning center point P defined by the first drive wheel 4 and the left and right road wheels 6L, 6R.

As described above, the second drive wheel 7
By providing a control device 10 in which the extension line C2 of the axis of rotation intersects a turning center point P defined by the first drive wheel 4 and the left and right road wheels 6L, 6R, whereby Ackermann-Jant theory is achieved. Accordingly, the vehicle can turn while minimizing the slip of the second drive wheel 7. Here, the turning center point P is, as shown in FIG. 1, an extension line C of the rotation axis of the left and right road wheels 6L, 6R,
It can be defined as an intersection with the extension C1 of the rotation axis of the first drive wheel 4 which is turned by the handle 3.

The control device 10, as shown in FIG.
In this example, a first steering angle detector 11 for detecting the steering angle θ1 of the first drive wheel 4 and a second steering angle detector 12 for detecting the steering angle θ2 of the second drive wheel 7
And a steering motor 14 for steering the second drive wheel 7, a motor drive unit 27 for controlling the drive of the steering motor 14, and an arithmetic processing unit for outputting a drive signal to the motor drive unit 27. Are illustrated.

The first and second steering angle detectors 11 and 12
Consists of, for example, a potentiometer, detects the steering angle as a voltage signal, and inputs it to the input port I / O. The steering angle detectors 11 and 12 may employ various types of detectors such as a magnetic sensor and an optical sensor in addition to the potentiometer.

The arithmetic processing unit includes, for example, a CPU serving as a central processing unit, a ROM serving as a storage unit in which a processing procedure of the CPU and known data are stored in advance, a RAM serving as a temporary storage memory for work, Fill in, output port I / O
And a data bus connecting these as appropriate.

Next, the processing procedure of the control device 10 will be described. In this example, first, based on the steering angle θ1 of the first drive wheel 4, a target steering angle θ2A at which the extension line C2 of the rotation axis of the second drive wheel 7 intersects the turning center point P is calculated.

For example, as shown in FIG. 1, plane coordinates XY fixed to the reach type forklift R are set. X
The axis is an extension line C of the left and right road wheels 6L and 6R.
And the Y axis is the first drive wheel 4
Through the steering center point D1. First, assuming that the wheel base of the reach type forklift R is B and the steering angle of the first drive wheel 4 is θ1, the X coordinate value Xp of the coordinates (Xp, 0) of the turning center point P is substantially the following equation. An equivalent operation can be performed. Xp = B / tan (θ1) ...

Next, the control device 10 determines that the extension of the rotation axis C2 of the second drive wheel 7 intersects the turning center point P defined by the first drive wheel 4 and the left and right road wheels 6L, 6R. The target steering angle θ2A of the second drive wheel is obtained. This target steering angle θ2A is
The coordinates Xp of the turning center point P, the distance M in the X direction between the steering center points D1 and D2 of the first and second road wheels, and the wheel base B are calculated by a calculation substantially equivalent to the following equation. You can ask. θ2A = tan ⁻¹ {B / (Xp−M)}

Next, the control device 10 outputs a signal corresponding to the target steering angle θ2A of the second drive wheel 7 to the motor drive unit 27. In the motor drive unit 27, the steering motor 14 is controlled so as to eliminate the deviation between the current steering angle θ2 of the second drive wheel 7 and the target steering angle θ2A.
Drive control.

When the control device 10 performs the above-described processing, the extension line C2 of the rotation axis of the second drive wheel 7 is determined by the first drive wheel 4 and the left and right road wheels 6L and 6R. The steering can be performed in a direction crossing the turning center point P, and the vehicle can turn while minimizing the slip of the second drive wheel 7.

The first and second motors M1, M2 may be connected in series or in parallel. When the first and second electric motors M1 and M2 are connected in series, an electric differential rotation action is obtained. The motor driving the wheel with the smaller turning radius decelerates, and the motor driving the wheel with the larger turning radius increases in speed according to the deceleration.

When the motors M1 and M2 are connected in parallel, for example, using the configuration of the control device 10,
The first motor M1 is drive-controlled at a rotation speed V1 proportional to the operation amount of the accelerator device 13, and turning radii, which are distances from the turning center point P to the first and second drive wheels, are L1 and L2. At this time, it is desirable that the rotation speed V2 of the second electric motor is controlled to be V1 · L2 / L1. These drive signals are obtained by the arithmetic processing unit and output to the motor controllers 29 and 30 that drive the first and second electric motors M1 and M2.

As a result, the first and second drive wheels 4, 7 move at the same angular velocity around the same turning center point, so that there is no slip between the running wheels and smooth turning can be realized. be able to. The turning radii L1 and L2 can be obtained by a calculation substantially equivalent to the following equation. L1 = Xp / COS (θ1) L2 = (Xp−M) / COS (θ2A)

As described in detail above, the present invention is not limited to the above-described embodiment, but may be modified in various forms, and in order to reduce the height dimension of the components of the second drive wheel 7. For example, the second electric motor M2 may be placed horizontally, and the wheel diameter may be smaller than that of the first drive wheel 4. Further, the left and right road wheels can be steered.

[0038]

As described above, according to the first and second aspects of the present invention, the vehicle body of the reach-type forklift is provided with the second steerable drive wheel that can be driven to rotate. As a result, the driving force and the contact area of the driving wheels can be greatly expanded, so that sufficient driving force can be obtained even when the center of gravity changes due to loading of loads or on slippery road surfaces, etc. And workability can be prevented from lowering.

Further, by providing a control device for steering the second drive wheel in a direction in which an extension of the axis of rotation intersects a turning center point P defined by the first drive wheel and the left and right road wheels, According to Ackerman-Jant's theory, the vehicle can turn with a minimum sliding friction between the second drive wheel and the road surface.

According to the third aspect of the present invention, the first electric motor is drive-controlled at a rotational speed V1 proportional to the operation amount of the accelerator device, and the distance from the turning center point P to the first and second drive wheels is controlled. Are L1 and L2, the first and second drive wheels are driven at the same angular velocity around the same turning center point in order to drive-control the rotational speed V2 of the second electric motor at V1 · L2 / L1. Because of the movement, smooth turning can be realized without slippage between the running wheels.

Further, in the invention according to claim 4, the first,
The second drive wheel is attached by first and second wheel supports, and the first and second wheel supports are joined by a link-like body that swings around a horizontal axis in a vehicle body center line direction. By displacing the drive wheel and the second drive wheel up and down in a seesaw manner, the road surface followability of the first and second drive wheels can be increased, and furthermore, the slip can be suppressed and the impact can be suitably absorbed. Ride comfort can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a reach-type forklift.

FIG. 2 is a view of a body portion of the reach type forklift as viewed from the rear.

FIG. 3 is a block diagram illustrating an example of a control device.

FIG. 4 is a side view of a conventional reach-type forklift.

[Explanation of symbols]

 Reference Signs List 2 vehicle body 3 steering wheel 4 first drive hole 5L, 5R left and right straddle arms 6L, 6R left, right road wheel 7 second drive wheel provided, 10 control device 11 first steering angle detecting means 14 Electric motor for steering 27 Motor drive unit R Reach type forklift M1 First electric motor M2 Second electric motor

Claims (4)

[Claims] 1. A road wheel having a first drive hole rotatably driven by a first electric motor and steerable by operating a steering wheel in a vehicle body, and rotatable to left and right straddle arms protruding from the vehicle body. A reachable forklift provided with: a second steerable drive wheel rotatably driven by a second electric motor is provided on the vehicle body, and the second drive wheel is extended by a rotation shaft thereof. A reach type forklift comprising a control device for steering in a direction in which a line intersects a turning center point P defined by the first drive wheel and the left and right road wheels. 2. The control apparatus according to claim 1, wherein the control device comprises: a first steering angle detecting means for detecting a steering angle θ1 of the first drive wheel;
A steering motor for steering the second drive wheel, a motor drive unit for driving and controlling the steering motor,
Based on the steering angle θ1, a target steering angle θ2A at which an extension of the rotation axis of the second drive wheel intersects the turning center point P is calculated, and the second drive wheel is steered to the target steering angle θ2A. The reach-type forklift according to claim 1, further comprising an arithmetic processing unit that outputs a drive signal to the motor drive unit. 3. The control device controls the drive of the first electric motor at a rotation speed V1 proportional to an operation amount of an accelerator device, and turns the first electric motor from the turning center point P to first and second drive wheels. The reach-type forklift according to claim 2, wherein when the radii are L1 and L2, the driving speed of the rotation speed V2 of the second electric motor is controlled by V1 / L2 / L1. 4. The first and second drive wheels are attached by first and second wheel supports, and swing the first and second wheel supports around a horizontal axis in the direction of the vehicle center line. 4. A splicing mechanism according to claim 1, wherein the first drive wheel and the second drive wheel are vertically displaced in a seesaw shape.
The reach-type forklift according to any one of the above.