JP2912486B2 - Low lift truck - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-lift truck, and more particularly, to a low-lift truck capable of improving operability by reducing steering force of a steering wheel.

[0002]

2. Description of the Related Art As shown in FIG. 9, when a load d is placed on a fork f of a low lift truck (hereinafter simply referred to as a low lift) a, the weight of the load d is increased by a drive wheel c which is a steering wheel and a drive wheel. Is carried by the load wheel e provided at the tip of the fork f. Here, assuming that the weight of the load d is W, the wheelbase is L, and the horizontal distance from the road wheel e to the center of gravity of the load d is X, the drive wheel c
Is increased by the weight of W · X / L as compared with the no-load state.

Conventionally, low lifts generally handle relatively light loads of 1 to 3 tons.
The number of cases where large and heavy loads such as t are handled is increasing. In such a case, as described above, the weight W of the load and the horizontal distance X from the load wheel e to the load center of the load d both increase, and accordingly, the shaft weight of the drive wheel c also increases. On the other hand, in the conventional low lift a,
Since the drive wheel is turned directly by the handle b, the steering force for steering the handle b increases with the increase in size, and there is a problem that it is difficult to steer.

According to the present invention, a steering torque applied to a steering wheel is detected, and an assist torque is generated from a power steering motor in accordance with the detected steering torque, thereby reducing the steering force of the steering wheel and improving operability. The purpose is to provide a new configuration of low lift.

[0005]

According to the present invention, a base (8) on which a revolving gear case (16) for supporting a drive wheel (3) is pivotably mounted, and a road wheel (4) are provided.
The steering gear case (16) comprises a vehicle body comprising a fork (5) disposed therein, and a handle (2) connected to the swing gear case (16), extending straight and having a grip (6) at a tip end. A low-lift truck that turns and steers a turning gear (13) around the turning gear case (16), and a power steering motor (1) is attached to the turning gear (13).
Pinion of 1) a (12) causes the engaged, the
The straight handle (2) is a movable post that can be swung.
(2B), and the magnitude and direction of the steering torque applied to the handle (2) are adjusted by the movable post (2B).
Steering torque detector detectable by swing angle (10)
Is provided on the steering wheel (2), and the steering torque detector (1 ) is provided .
The low lift truck is provided with a controller (30) for generating an assist torque of the power steering motor (11) based on the torque signal detected in (0) and rotating the pinion gear (12).

[0006]

When the steering wheel is steered to turn the low lift, the magnitude and direction of the steering torque applied to the steering wheel are detected by a steering torque detector built in the steering wheel, and the power steering is accordingly performed. The steering motor generates steering assist torque, which is transmitted to a turning gear that can steer the drive wheel, thereby reducing steering force and improving maneuverability.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1-3, the low lift 1 according to the present invention
Is a steering torque detector 10 that can detect the magnitude and direction of the steering torque applied to the steering wheel 2; a turning gear 13 fixed around a turning gear case 16 that can steer the drive wheel 3; The power steering motor 11 can supply assist torque to the gear 13, and the controller 30 determines the assist torque of the power steering motor 11.

The low lift 1 includes a base unit 8 containing a loading motor (not shown), a traveling motor 14, a drive wheel 3, a turning gear case 16 capable of supporting and steering the drive wheel 3, and the like. 8, a battery storage unit 7, which is mounted to be movable up and down via a well-known lift mechanism (not shown) using a link mechanism, and a pair of left and right forks 5, 5 welded to a lower portion of the battery storage unit 7.
The handle 2 is disposed so as to be able to be freely lifted up. In addition, the lifting mechanism raises and lowers the load wheels 4, 4 disposed at the tips of the forks 5, 5, respectively, and moves the forks 5, 5 up and down to perform a cargo handling operation.

As shown in FIG. 3, the slewing ring 1 made of a large-diameter bearing is provided around the slewing gear case 16.
By 8 inner race is fixed, and to fix the outer race support 17 of the base body 8,
The turning gear case 16 that supports the drive wheel 3 is turned freely. Further, the turning gear case 16 has a built-in gear reducer (not shown) for transmitting the torque of the traveling motor 14 to the drive wheel 3 which is gear-down and supported by the deviation portion K.

The gear case 16 has a hook portion 15 on the upper surface thereof for supporting the handle 2. Therefore, when the steering wheel 2 is turned to the left or right, a turning gear case 16 rotatably attached to the turning ring 17 is provided.
The handle 2 is thus connected to the turning gear case 16 via the hook 15. Thereby, the drive wheel 3 can be steered.

The power steering motor 11 is fixed to the base body 8, and a pinion gear 12 fitted to a drive shaft thereof meshes with a conversion gear 13 fixed around the turning gear case 16. .

The handle 2 is mounted on the base post 2A pivotally supported by the hook 15 via a horizontal pin 19 so as to be able to swing up. The steering torque detector 10 detects a minute swing angle of the movable post 2B generated when the steering wheel 2 is steered. The traveling motor 1
The handle 4 is driven while adjusting the traveling speed by operating an accelerator grip 6 provided at the tip of the movable post 2B of the handle 2.

As shown in FIGS. 4 and 7, the steering torque detector 10 projects into the base post 2A of the rectangular tube at a position beyond the pivot 9 at one end of the movable post 2B. The protrusion 20 is formed. Further, substantially L-shaped claw pieces 21A and 21B are fixed to the protruding portion 20 so as to be shifted vertically. The projection 20 has a guide shaft 2.
7 penetrate, and furthermore, springs 24 and 25 for pressing the protrusion 20 from left and right are elastically inserted into the guide shaft 27. Thereby, the base side, movable side post 2A, 2B
Are usually kept in a neutral position that is linear.

[0014] Potentiometers 22 and 23 are respectively provided on the inside of the left and right claw pieces 21A and 21B by a bracket 26 at the fixed side post 2A. The potentiometers 22 and 23 are vertically moved and their detection axes 2
By arranging the 2A and 23A in directions opposite to each other, it is possible to house and arrange in the narrow handle 2.

The driver holds the accelerator grip 6 and moves the steering wheel 2 to the right or left with the springs 24, 2 or
5, the movable post 2B first pivots about the pivot 9, and at this time, a small relative displacement (swing angle) occurs between the movable post 2B and the base side post 2A. . As a result, the claw piece 21 fixed to the projection 20
A or 21B is the detection axis 2 of the potentiometers 22 and 23
By pressing either 2A or 23A, the steering torque applied to the steering wheel 2 is finally detected as a linear displacement.

For example, FIG. 5 shows a case where the handle 2 is turned counterclockwise in the figure, and the claw 21B pushes the detection shaft 23A of the potentiometer 23, and FIG. This indicates a case in which the rotation is made around, and the claw piece 21A pushes the detection shaft 22A of the potentiometer 22. When the steering of the steering wheel 2 is stopped, the urging force of the springs 24 and 25 causes
The movable post 2B and the fixed post 2A return to a neutral state.

Next, the controller 30 will be described with reference to FIG. A voltage corresponding to the steering torque detected by the potentiometers 22 and 23 for detecting left and right steering torques is supplied to a motor for driving a power steering motor via a buffer A via a bias adjustment circuit, a gain adjustment circuit and a buffer B. The power steering motor 11 is rotationally driven through a drive circuit.

The bias adjustment circuit is a circuit for correcting a shift of the center point caused by a mounting error of the potentiometers 22 and 23 capable of detecting the steering torque and the springs 24 and 25 for maintaining the projection 20 in a neutral state. For example,
It consists of a variable resistor and an operational amplifier. In addition, the gain adjustment circuit transmits a vibration or the like during traveling of the low lift 1 to the steering wheel 2 and outputs a steering torque signal of the torque detector 10 even though the steering wheel 2 is not steered. Since a so-called hunting phenomenon occurs in the motor 11, predetermined amplification is performed with a time constant to prevent hunting. The gain adjustment circuit can adjust the gain by using a variable resistor or the like, and is configured so that the assist torque can be adjusted so that the steering feeling is optimized.

The motor drive circuit comprises a chopper circuit and the like, and rotates the power steering motor 11 by a predetermined amount in proportion to the voltage from the buffer B. Incidentally, VR1 and VR2 are variable resistors for adjusting a zero point shift due to an error when the potentiometers 22 and 23 are mounted.

The low lift of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the present embodiment, a steering torque detector using a potentiometer has been illustrated, but various detectors such as a strain gauge and a differential transformer can be used. Further, the position where the steering torque detector is provided may be any one of the central part, the lower part and the upper part of the steering wheel.

[0021]

As described above, when the steering torque is applied, the assist torque corresponding to the applied steering torque is generated by the power steering motor and transmitted to the turning gear case supporting the drive wheel, thereby increasing the weight of the load. Accordingly, even when the shaft weight of the drive wheel increases, the steering wheel can be steered with a small steering force, so that operability can be improved and cargo handling efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a side view showing one embodiment of a low lift of the present invention.

FIG. 2 is a plan view showing one embodiment of the low lift truck of the present invention.

FIG. 3 is a front view showing a turning gear case.

FIG. 4 is a cross-sectional view illustrating a steering torque detector.

FIG. 5 is a sectional view showing the operation of the steering torque detector.

FIG. 6 is a sectional view showing the operation of the steering torque detector.

FIG. 7 is a cross section illustrating a steering torque detector.

FIG. 8 is a diagram illustrating a controller.

FIG. 9 is a side view illustrating a conventional low lift.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Low lift 2 Handle 3 Drive wheel 4 Road wheel 5 Fork 7 Battery storage part 8 Base part 10 Steering torque detector 11 Power steering motor 12 Pinion gear 13 Conversion gear 16 Revolving gear case 30 Controller

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-113645 (JP, A) JP-A-5-8738 (JP, A) JP-A-3-295768 (JP, A) JP-A 63-113768 266327 (JP, A) JP-A 63-64577 (JP, U) JP-A 3-5679 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B62D 5/04 B62D 1 /twenty two

Claims (1)

(57) [Claims] 1. A base (8) on which a revolving gear case (16) for supporting a drive wheel (3) is pivotably mounted.
And a fork (5) on which a road wheel (4) is arranged, and a handle (2) connected to the revolving gear case (16), extending straight, and having a grip (6) at the tip. A low-lift truck for turning and steering the turning gear case (16), wherein a turning gear (13) is provided around the turning gear case (16).
The pinion gear (12) of the power steering motor (11) is meshed with the reversing gear (13), and the linear handle (2) is swiveled by the movable post.
(2B), and the magnitude and direction of the steering torque applied to the handle (2) can be adjusted by the movable side post (2B).
Steering torque detector which can be detected by the swing angle (1
0) is provided on the steering wheel (2), and based on the torque signal detected by the steering torque detector (10), the assist torque of the power steering motor (11) is generated to rotate the pinion gear (12). A low-lift truck provided with a controller (30) that performs the operation.