JP2527286B2 - Reach type forklift - Google Patents

Description

Detailed Description of the Invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reach type forklift having excellent workability by enabling the left and right road wheels to be driven to prevent slippage at the time of starting, which is likely to occur on slippery road surfaces.

[0003]

2. Description of the Related Art As shown in FIG. 7, a conventional reach-type forklift (hereinafter simply referred to as a forklift) F is
The main body 2 is provided with a drive wheel 11 that can be steered by the steering wheel 6 and a road wheel 12L,
Straddle arms 10 and 10 that rotatably support 2R
In between, a mast 3 that locks cargo handling devices 4, such as a fork that can be moved up and down by a lift cylinder 5, is provided to be able to move back and forth.

The main body 2 is provided with various hydraulic operating levers 7, an accelerator lever 8 for driving the drive wheel 11 to rotate, and a battery 9. The drive wheel 11 is used for traveling via a gear reducer. By being linked with an electric motor (both not shown), it is rotationally driven according to the operation amount of the accelerator lever 8.

By the way, when the mast 3 is forwarded in a state where a load is loaded on the cargo handling tool 4, the center of gravity moves to the front of the vehicle, and the axle weight acting on the drive wheel 11 decreases. In such a state, even if an attempt is made to start the forklift F on a road surface having a low coefficient of friction, for example, on wet concrete, or on a frozen frozen storage floor, the drive wheel 11 slips and cannot be started, particularly in severe cases. .

Therefore, when the vehicle starts moving, regardless of whether the accelerator lever 8 is tilted or not, the current to the electric motor for traveling is reduced to suppress the torque generated by the electric motor.
A slip countermeasure for preventing a slip due to a sudden start has been proposed.

[0007]

However, when the current to the electric motor for traveling is reduced, although a certain effect can be expected in the prevention of slip, it takes time to start the forklift and the cycle time of the cargo handling work is reduced. There is a problem of lowering the workability and impairing the workability. In addition, there is a problem that the forklift cannot start on an uphill or the like due to a lack of torque and is stuck.

It is an object of the present invention to provide a reach type forklift which prevents slipping even on a slippery road surface and is excellent in workability.

[0009]

DISCLOSURE OF THE INVENTION The present invention includes a load wheel attached to the tip of the left and right straddle arms and independently driven to rotate by an auxiliary electric motor, and a main body portion rotatably supported by a steering handle. A drive wheel connected to a traveling electric motor, means for detecting an operation amount of an accelerator lever, and a steering angle detector for detecting a steering angle of the drive wheel, and a drive obtained from the steering angle detector. The turning center of the vehicle body is calculated from the steering angle of the wheels, and the turning radii of each of the drive wheel and the left and right road wheels are calculated from the turning center, and each auxiliary electric motor is calculated based on the operation amount of the accelerator lever. Multiplied by the signal and the ratio of the turning radius of each road wheel to the turning radius of the drive wheel A control device capable of outputting a motion signal which is reach truck formed by providing.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. The reach type forklift 1 is provided with left and right straddle arms 15, 15 on both sides of a front portion of a main body 2, and supports load wheels 16L, 16R at the distal ends thereof, and auxiliary motors 17L, 17R capable of rotating these.
Equipped. In addition, the main body 2 is provided with a drive wheel 11 and a control device 19 that are linked to a traveling electric motor 18 that can be turned by a steering handle and can be rotationally driven according to the tilt angle and direction of the accelerator lever 8.

As shown in FIG. 2 (the right side road wheel 16R also has a similar structure), the drive mechanism for the left side road wheel 16L uses a single plate 20 for the straddle arm 15 to form a gear reduction mechanism. The gear box 21 that is built in and supported is integrally fixed, thereby suppressing an increase in the width of the straddle arm 15.

The gearbox 21 includes an auxiliary electric motor 1
A transmission shaft 25 having an idle gear 24 meshed with a pinion gear 23 fixed to the 7L output shaft 22 is arranged, and a bevel pinion gear 26 at the other end of the transmission shaft 25 meshes with a bevel gear portion 27 of an idle shaft body 29. .

The spur gear portion 28 at the other end of the idle shaft body 29 is meshed with the final gear 31 of the drive shaft 32 via the intermediate spur gear 30. The drive shaft 32 is
The cylindrical portion 33 of the gear box 21 is supported by tapered roller bearings B, B assembled on the back. The gear box 21 is filled with gear oil, and the space between the gear box 21 and the plate 20 is oil-tight.

As shown in the control block diagram of FIG. 3, the accelerator lever 8 is provided with accelerator lever operation amount detecting means capable of detecting the operation amount thereof. In this embodiment, this means comprises a potentiometer 34 for detecting the amount of rotation of the cam piece 8A which rotates together with the accelerator lever 8, for example. The drive signal V of the traveling motor 18 is determined via a drive signal determination circuit 35 that can be determined. In this example, a drive signal V that is linearly proportional to the operation amount of the accelerator lever 8 is output. However, various other functions such as a quadratic function may be used.

Drive wheel 11 which is a steering and driving wheel
Is provided with a steering angle detector 38 for detecting the steering angle. The steering angle detector 38 is, for example, a potentiometer that detects the rotation angle of the gear case G that rotates with the drive wheel, that is, the steering angle θ, and the steering angle θ is input to the arithmetic circuit 37.

The arithmetic circuit 37 is the drive wheel 1
While calculating the turning center point of the vehicle body from the steering angle θ of 1,
The turning radius from the turning center point to the drive wheel 11 and the turning radii of the left and right road wheels 16L and 16R are calculated.

The left and right road wheels 16L and 16R are obtained by multiplying the drive signal V to the drive wheel 11 by each ratio of the turning radii of the left and right road wheels 16L and 16R to the turning radius of the drive wheel 11. As a drive signal, the left and right road wheels 16L, 16R
To the auxiliary electric motors 17L and 17R.

The arithmetic circuit 37 has a sampling cycle
From the steering angle θ obtained by the steering angle detector 38, the present turning center point P of the forklift 1 is calculated. The turning center point P is, as shown in FIG.
Since the 6L and 16R are rotatably supported only in the longitudinal direction of the straddle arms 15 and 15, they are located on the axis R that connects the rotation centers of the left and right road wheels 16L and 16R, and therefore, the drive wheel. The intersection of the rotation center line F of 11 and the axis R is the turning center point P.

Here, assuming a rectangular coordinate system whose origin is the steering center O of the drive wheel 11, the forklift 1
Assuming that the steering angle of the drive wheel 11 is θ, the equation of the rotation center line F of the drive wheel 11 in the coordinate system is as follows. The steering angle θ is
The counterclockwise direction is positive with respect to the X axis. Y = tan θ · X ...

The linear equation of the axis R where the turning center points P are lined up is an equation, where L is the wheel base of the forklift 1. Y = L ...

Therefore, when the solutions of the above and are obtained, the coordinates (XP, YP) of the turning center point P of the forklift 1 can be obtained as shown in the equation. (XP, YP) = (L · cot θ, L) ...

Next, the left and right road wheels 16L, 16
If the distances between the R and Y axes are WL and WR, respectively, the left and right road wheels 16L and 16 from the turning center point P.
The respective turning radii L1 and L2 up to R are, as shown in the equations and, from the X coordinate of the turning center point P, the distance W
It is sufficient to adjust L and WR. L1 = XP + WL ... L2 = XP-WR ...

The turning radius L3 from the drive wheel 11 to the turning center point P can be obtained by the equation 1.

[0024]

[Equation 1]

Next, based on the left and right road wheels 16L, 16R and the turning radii L1, L2, L3 of the drive wheel 11 and the drive signal V determined by the drive signal determination circuit 35, the left and right sides are obtained. Drive signals VL and VR of the road wheels 16L and 16R are determined. Drive signals VL to auxiliary electric motors 17L and 17R that link the left and right road wheels 16L and 16R,
VR is determined by the equations and. VL = V * L1 / L3 ... VR = V * L2 / L3 ...

Such left and right road wheels 16
The drive signals VL and VR of L and 16R are output to the left and right auxiliary electric motor drive circuits 40L and 40R such as a chopper circuit,
Each auxiliary electric motor 17L, 17R can be rotationally driven.

Thus, the left and right auxiliary electric motors 17L, 1
The drive signals VL and VR of the 7R are calculated by multiplying the drive signal V of the traveling electric motor 18 by the ratio of the respective turning radii to calculate the drive wheels 11 and the left and right road wheels 16L and 16L.
By turning at the same angular velocity with respect to the turning center point P between all the driving wheels of R, smoothing is performed without slippage between the driving wheels and restraint of the auxiliary electric motors 17L, 17R, etc. This is to prevent burnout and the like due to.

Next, as shown in FIG. 5, when the turning center point P can be located between the left and right road wheels 16L and 16R, L2 calculated by the above equation becomes a negative value. The drive signal VR to the right auxiliary motor 17R has a negative output, and its rotation direction is opposite to that of the left auxiliary motor 17L.

Incidentally, as shown in FIG. 6, when the steering wheel operation is performed in the opposite manner to the above case, the rotation center line F of the drive wheel 11 is expressed by the formula. Y = tan (−θ) · X ...

Therefore, the turning center point P can be obtained by solving the equation and the above equation. (XP, YP) = (− L · cot θ, L) ...

The left and right road wheels 16L, 16
The turning radii L1 and L2 of each R are as shown in equations (10) and (11). L1 = −L · cot θ + WL = XP + WL (10) L2 = −L · cot θ−WR = XP−WR (11)

Therefore, if the positive and negative signs of the steering angle θ are set to the left and right with reference to the upright state, the above equation can be satisfied regardless of whether the steering angle is positive or negative. The distance between the wheel base L of the forklift 1 or the Y axis of the reference coordinate axis and the left and right road wheels 16L and 16R is stored in advance in the arithmetic circuit.

The present invention is not limited to the above-mentioned embodiment, and for example, the drive mechanism of the road wheel may employ transmission by a belt or a chain in addition to the combination of gears, and a traveling electric motor and an auxiliary electric motor. As the drive signal of, the voltage, the current, the generated torque, the number of revolutions, or the like can be used and various changes can be made.

[0034]

As described above, according to the present invention, not only the drive wheel provided at the rear of the main body of the vehicle body as in the prior art but also the road wheel pivotally supported at the tip of the straddle arm can be driven. Even if there is a change in the center of gravity due to the presence or absence of loading of the mast, the extension of the mast, the retraction of the mast, etc., sufficient traction can be obtained. Prevents deterioration of workability.

Further, the drive signal of the auxiliary electric motor for driving the left and right road wheels is set to the drive signal of the traveling electric motor for driving the drive wheel, and the ratio of the turning radius of each of the left and right load wheels to the turning radius of the drive wheel is set. Since it has a control device that can output as a multiplied product, all driving wheels are driven at the same angular velocity around the same point, and there is no slip between the wheels during turning and smooth turning is possible. In addition, it is possible to prevent the seizure of the auxiliary electric motor.

[Brief description of drawings]

FIG. 1 is a plan view illustrating an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a driving mechanism of a road wheel.

FIG. 3 is a control block diagram of the present invention.

FIG. 4 is a plan view for explaining the contents of calculation of the present invention.

FIG. 5 is a plan view for explaining the contents of calculation of the present invention.

FIG. 6 is a plan view for explaining calculation contents of the present invention.

FIG. 7 is a side view for explaining a conventional reach-type forklift.

[Explanation of symbols]

 1 Reach type forklift 2 Main body 8 Accelerator lever 9 Battery 11 Drive wheel 15 Straddle arm 16L Road wheel 16R Road wheel 17L Auxiliary electric motor 17R Auxiliary electric motor 18 Driving motor 34 Potentiometer 35 Drive signal determination circuit 36 Driving electric motor driving circuit 37 Computational circuit 38 Steering angle detector 40L Auxiliary motor drive circuit 40R Auxiliary motor drive circuit

Claims (1)

(57) [Claims] 1. A road wheel attached to the tip of the left and right straddle arms and independently rotated by an auxiliary electric motor, and a drive rotatably supported by a steering wheel on the main body and connected to a traveling electric motor. The vehicle includes a wheel, a means for detecting an operation amount of an accelerator lever, and a steering angle detector for detecting a steering angle of the drive wheel, and the vehicle body turns from the steering angle of the drive wheel obtained from the steering angle detector. The center point is calculated, and the respective turning radii from the turning center to the drive wheel and the left and right road wheels are calculated, and a signal based on the operation amount of the accelerator lever and a turning radius of the drive wheel are given to each auxiliary electric motor. Control device capable of outputting a drive signal multiplied by the ratio of the turning radius of each road wheel to Reach truck to be provided. [0001]