JP2002059845A - Lift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely travel forward and backward at a desired speed. SOLUTION: In a lift truck having an operation arm 13 extending backward from a self traveling truck main body 3 arranging a lift 7 on a front part thereof and changing a traveling direction of the truck main body 3 by a swing of the operation arm 13 in left or right, a grip part 25 provided on a tip part of the operation arm 13 through a handle 14 is formed elastically displacable in a forward and backward directions (a), (b) of the truck main body 3, and a strain gage 26 detecting a elastic displacement of the grip part 25 is provided. The truck main body 3 is traveled forward (a) or backward (b) according to a detected signal from the strain gage 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lift truck capable of safely moving a low-lift type lift truck or the like forward and backward at a desired speed.

[0002]

2. Description of the Related Art FIGS. 12 and 13 show an example of a conventional low-lift type lift truck. this is,
One drive wheel 1 and two caster wheels 2
And a motor 5 with an electromagnetic brake 5a for rotating the drive wheel 1 forward and reverse through a gear mechanism 4 so as to be rotatable around a vertical axis O. While being placed, the truck body 3
The start switch 6 is provided on the upper surface of the casing 3a.

A pair of left and right lifts 7 are provided at the front of the truck body 3 so as to be able to move up and down, and a load wheel 9 provided at the end of each lift 7 via a swing bracket 8 is grounded to the floor F. The piston rods of a pair of right and left hydraulic cylinders 10 provided in the truck body 3 are connected to a swing bracket 8 via a link mechanism 11.

Further, the casing 3a is
5b extending upward along the vertical axis O
The operation arm 13 is connected to the bearing portion 5b via a connection shaft 12 so as to be vertically movable within a predetermined angle α (about 90 °). The handle 1 is protruded, and the handle 1
By gripping and swinging the drive wheel 1 left and right, the drive wheel 1 can be rotated about the vertical axis O via the operation arm 13 and the electric motor 5, and the traveling direction of the truck body 3 can be freely changed.

[0005] A pair of left and right operation rings 15 rotatably fitted to the distal ends of the handles 14 are integrally connected to each other via a connection shaft 16.
A rotary potentiometer (detector) 17 built in 4 is connected to one operation ring 15, and the operation ring 15 is turned c or clockwise d from the neutral position N.
By doing so (see FIG. 15), the electric motor 5 is rotated forward or backward based on the detection signal of the potentiometer 17 for detecting this, and the truck body 3 is moved forward a or backward b at a desired speed. Reference numeral 18 denotes a lifting spring that urges the operation arm 13 upward. Reference numeral 19 denotes a slight angle β between the standing state of the operation arm 13 (see the phantom line in FIG. 12) and the horizontal state of the operation arm 13 (see the solid line in FIG. 12). Brake switches 20 to 22 for detecting the state of being pressed down (about 3 °) and activating the electromagnetic brake 5 a are a lift button for raising and lowering and an emergency stop button, and are provided on the distal end surface of the operation arm 13.

In the above configuration, when the load W is lifted up, the start switch 6 is turned on, and the operator M grasps one handle 14 and operates the operation arm 13.
Down to a substantially horizontal state (see the solid line in FIG. 12), and FIG.
As shown in FIG. 4 and FIG.
Of the truck body 3 at a desired speed by turning the operation ring 15 counterclockwise from the neutral position N, and moving the lift 7 under the load W, The user may press the lift button 20. Thus, by causing the hydraulic cylinder 10 to extend and drive, the swing bracket 8 is erected via the link mechanism 11, and the lift 7 can be lifted to lift the load W (see the phantom line in FIG. 12).

[0007] When transporting the load W to a predetermined position,
By turning the operation ring 15 counterclockwise from the neutral position N in the same procedure as described above, the truck body 3 is advanced a at a desired speed, or by turning the operation ring 15 clockwise from the neutral position N, What is necessary is just to move the truck body 3 backward at a desired speed.

In order to lift down the luggage W, the lowering lift button 21 may be pressed. As a result, the hydraulic cylinder 10 is driven to contract, whereby the link mechanism 11
The swing bracket 8 is tilted down through this, and the lift 7 can be lowered to drop the load W (see the solid line in FIG. 12).

[0009]

In the above-mentioned conventional configuration,
For example, when the truck body 3 is moved backward b, the operation ring 1 is operated by the thumb Ma with the operator M facing backward.
5 (see FIGS. 14 and 15), and it is necessary to operate the operation ring 15 in an unreasonable posture and in a state where it cannot be seen.
It is difficult to operate the truck body 5 smoothly.
Is too slow or too fast, and it is difficult to keep the running speed of the truck body 3 appropriate. In particular, when the running speed is too fast, the truck body 3 may come into contact with the operator M. Yes, there is a problem with safety.

An object of the present invention is to provide a lift truck capable of safely moving back and forth at a desired speed in view of the above-mentioned conventional drawbacks.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, an operation arm extends rearward from a self-propelled truck body having a lift disposed at a front portion thereof. In a lift truck in which the running direction of the truck body is changed by swinging the arm to the left and right, a grip provided at the tip of the operation arm is formed to be elastically displaceable in the front-rear direction, and A detector for detecting elastic displacement is provided, and the truck body is moved forward or backward based on a detection signal of the detector.

According to the above configuration, by gripping and pushing and pulling the grip provided at the distal end of the operation arm, the grip is elastically displaced forward or backward, and the detector for detecting the elastic displacement is used. Based on the detection signal, the track body can be moved forward or backward at a speed proportional to the elastic displacement width.In this case, the direction of forward and backward movement of the track body and the push-pull direction of the gripping part match, The operator can smoothly move the truck body back and forth at a desired speed in an easy operation posture. Therefore, for example, even when the operator moves the truck body backward while facing backward, the truck body can be safely driven so as not to contact the operator.

According to a second aspect of the present invention, in the first aspect of the present invention, the holding portion has a leaf spring and an elastically displaceable grip externally fitted to the leaf spring, and the leaf spring is provided with the operating member. The arm is provided between a pair of left and right handles protruding from both side surfaces of the distal end of the arm, and the elastic displacement of the leaf spring is detected by a detector.

According to the above construction, the grip body is simply pushed and pulled back and forth to move the track body in proportion to the elastic displacement width based on the detection signal of the detector for detecting the elastic displacement of the leaf spring. At the set speed in the direction of displacement. Further, the leaf spring can be firmly attached to the distal end of the operation arm via the pair of left and right handles.

According to a third aspect of the present invention, in the second aspect, the detector comprises a strain gauge attached to the leaf spring.

According to the above configuration, the pushing / pulling force applied to the grip portion and the pushing / pulling direction can be accurately detected by the strain gauge, and the truck body can be moved forward or backward as desired based on the detection signal. Can be. Further, since the strain gauge is merely attached to the leaf spring, the structure is simple and the manufacturing cost is low.

According to a fourth aspect of the present invention, in the second aspect of the present invention, a branch rod extending forward from the leaf spring is provided, and the displacement of the distal end of the branch rod is detected by the detector. It is characterized by:

According to the above construction, the displacement of the leaf spring is detected by the detector via the branching rod, and the detector is separated from the grip having the leaf spring. Even if it hits an obstacle, the detector can be protected from the obstacle.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the branch rod is supported by the support frame protruding from the operation arm so as to be movable back and forth.

According to the above configuration, the tip end of the branch rod can be reliably supported by the support frame so as not to be displaced from the detector.

The invention according to claim 6 is the invention according to claim 4 or 5.
In the described invention, the detector is arranged along the operation arm.

According to the above configuration, the detector can be arranged so as not to be bulky along the operation arm.
The operating arm can protect the detector from obstacles.

According to a seventh aspect of the present invention, in any one of the fourth to sixth aspects, the detector comprises a potentiometer engaged with a tip end of the branch rod.

According to the above configuration, the push-pull force applied to the grip portion and the push-pull direction applied to the grip portion can be precisely detected by the potentiometer via the branch rod, and the track body is advanced as desired based on the detection signal. Or you can go backwards.

[0025]

FIGS. 1 and 2 show a low-lift type lift truck according to a first embodiment of the present invention. 14, a grip 25 provided between the distal ends of the handles 14 is formed to be elastically displaceable in the front-rear direction, and a strain gauge (detector) 26 for detecting the elastic displacement of the grip 25 is provided. Is provided. Since the configuration other than the above is almost the same as the configuration shown in FIGS. 12 and 13,
The same portions are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIGS. 3 to 6, the grip 25 has a substantially circular cross-section grip made of a leaf spring 25A and an elastic material such as an elastically deformable sponge externally fitted to the leaf spring 25A. 25B, both ends of the leaf spring 25A are inserted and fixed in slits 27 formed at the tip of each handle 14, and a strain gauge 26 is attached to the front center (or rear center) of the leaf spring 25A. Have been. In FIG. 6, reference numeral 28 denotes a cord connected to the strain gauge 26.

The function of the forward and backward movements a and b of the truck body 3 will be described based on the above configuration. In the state where the grip portion 25 is not pushed or pulled, as shown in FIG. It is linear and held at the neutral position N, the tensile stress and the compressive stress are not applied to the strain gauge 26, and the truck body 3 is stopped.

When the truck body 3 is advanced a from the above state, the operator M may hold the grip 25 and push the operation arm 13 forward e. As a result, FIG.
As shown in (b), when the leaf spring 25A is elastically deformed from the neutral position N forward e by an elastic displacement width h1 proportional to the pushing force, a tensile force is applied to the strain gauge 26, and the tensile force is applied by the tensile force. The electric motor 5 is normally rotated at a predetermined speed based on a detection signal output from the strain gauge 26 in proportion to the elastic displacement width h1, and the truck body 3 can be advanced a at a desired speed.

When the truck body 3 is moved backward b, the operator M may hold the grip 25 and pull the operating arm 13 backward f. As a result, FIG.
As shown in the figure, the leaf spring 25A is elastically deformed from the neutral position N rearward by an elastic displacement width h2 proportional to the pulling force, whereby a compressive force is applied to the strain gauge 26, and the elastic displacement width due to the compressive force is applied. strain gauge 2 in proportion to h2
The motor 5 is reversed at a predetermined speed based on the detection signal output from the motor 6, and the truck body 3 can be moved backward b at a desired speed.

According to the above configuration, the grip 25B of the grip portion 25 is gripped and pushed and pulled, so that the grip portion 2
5 is elastically displaced forward or backward f, and the track main body 3 is moved forward or backward b at a speed proportional to the elastic displacement widths h1 and h2 based on a detection signal from a strain gauge 26 for detecting the elastic displacement. In this case, since the directions of the forward and backward movements a and b of the truck body 3 coincide with the pushing and pulling directions e and f of the grip portion 25, the operator M can easily move the truck body 3 in a desired operation posture. The forward and backward movements a and b can be smoothly performed at the speed. Therefore, for example, even when the operator M moves the truck body 3 backward b while facing the rearward f, the truck body 3 can be safely driven so as not to contact the operator M. Also,
Since the leaf spring 25A is provided between the pair of left and right handles 14 protruding from both sides of the distal end of the operation arm 13, the leaf spring 25A can be firmly attached to the distal end of the operation arm 13. Further, the strain gauge 26 is connected to the leaf spring 2.
Since it is merely attached to 5A, the structure is simple and the production cost is low.

FIGS. 8 to 10 show a low-lift type lift truck according to a second embodiment of the present invention, which is a branch rod extending forward from the center of the lower surface of a leaf spring 25A along the operation arm 13. FIG. 30, the distal end portion 30a of the branch rod 30 is bent at a right angle toward the operation arm 13,
A pair of front and rear slide-type potentiometers (detectors) 1 in which detection rods 17a are brought into contact with both front and rear surfaces of the tip portion 30a.
7A and 17B are fixed to the operation arm 13 via the support frame 31, and the branch rod 3 is inserted into a through hole 32 penetrating the support frame 31.
0 is inserted to be able to move back and forth. In FIG. 8, 3
Reference numeral 4 denotes a protective cover that covers the potentiometers 17A and 17B, and is fixed to the operation arm 13. Since the configuration other than the above is substantially the same as that of the first embodiment shown in FIGS. 1 to 6, the same parts are denoted by the same reference numerals and description thereof will be omitted.

The function of the forward and backward movements a and b of the truck body 3 will be described based on the above configuration. When the grip portion 25 is not pushed or pulled, the leaf spring 25A is linear and is held at the neutral position N. (See FIG. 7 (a)),
As shown in FIG. 11A, both potentiometers 17
The protruding lengths H1 of the detection rods 17a of A and 17B are set to be the same, and the truck body 3 is stopped.

When the operator M grips the grip 25 and pushes the operating arm 13 forward e in order to advance the truck body 3 from the above state, the leaf spring 25A is moved to the neutral position N.
From the front to the front e (see FIG. 7B),
As shown in FIG. 11B, the distal end portion 30a of the branch rod 30
Is moved forward e, the detecting rod 17a of the front potentiometer 17A is pushed in, and its protruding length H2 is shortened, and the detecting rod 17a of the rear potentiometer 17B is protruded, and its protruding length H3 And the motor 5 is rotated forward at a predetermined speed based on the detection signals output from the potentiometers 17A and 17B in proportion to the protrusion lengths H2 and H3, and the truck body 3 is advanced a at a desired speed. be able to. In other words, if you press hard, the rotation speed of the electric motor 5 will increase and the truck will move forward quickly,
If it is pressed lightly, the number of revolutions of the electric motor 5 becomes low, and the truck moves forward slowly. Also, if the operator M stops, there is no pushing force, so the truck naturally slows down and stops.

Further, in order to move the truck body 3 backward b, the operator M
3 is pulled rearward f, the leaf spring 25A is elastically deformed from the neutral position N to the rear f (see FIG. 7C).
As shown in (c), when the distal end portion 30a of the branch rod 30 is moved backward f, the front potentiometer 17 is moved.
The detection rod 17a of the rear potentiometer 17B is protruded, the projection length H4 of the detection rod
7a is pushed in, the protruding length H5 is shortened, and the electric motor 5 is reversed at a predetermined speed based on the detection signals output from the potentiometers 17A and 17B in proportion to the protruding lengths H4 and H5, The truck body 3 can be moved backward at a desired speed.

According to the above configuration, substantially the same effects as those of the first embodiment can be obtained, and also the following effects can be obtained. That is, both potentiometers 17A,
Since the grip 17B is separated from the grip 25 having the leaf spring 25A, even if the grip 25 collides with an obstacle, for example, the two potentiometers 17A, 17B
Can be protected. Also, the through hole 3 of the support frame 31
Since the branch rod 30 is inserted through the second rod 2, the distal end portion 30a of the branch rod 30 can be reliably supported so as not to be displaced from the potentiometers 17A and 17B.

In the above-described second embodiment, two potentiometers 17A and 17B are used in order to improve accuracy, but one of them is omitted and one potentiometer 17A is omitted.
(Or 17B) alone. Further, various types of detection devices such as a load cell may be used instead of the potentiometers 17A and 17B.

[0037]

According to the first aspect of the present invention, by gripping and pushing and pulling the grip provided at the distal end of the operating arm, the grip is elastically displaced forward or backward, and the elastic displacement The truck body can be moved forward or backward at a speed proportional to the elastic displacement width based on the detection signal from the detector for detecting the forward and backward directions of the truck body and the push-pull direction of the gripping portion. Since they match, the operator can smoothly move the truck body back and forth at a desired speed in an easy operation posture. Therefore, for example, even when the operator moves the truck body backward while facing backward, the truck body can be safely driven so as not to contact the operator.

According to the second aspect of the present invention, the track body is elastically moved based on the detection signal of the detector which detects the elastic displacement of the leaf spring simply by gripping the grip and pushing and pulling the leaf spring back and forth. It can move forward or backward in the displacement direction at a speed proportional to the displacement width. Further, the leaf spring can be firmly attached to the distal end of the operation arm via the pair of left and right handles.

According to the third aspect of the present invention, the pushing / pulling force applied to the grip portion and the pushing / pulling direction can be precisely detected by the strain gauge, and the track body is advanced as desired based on the detection signal. Or you can go backwards. Further, since the strain gauge is merely attached to the leaf spring, the structure is simple and the manufacturing cost is low.

According to the fourth aspect of the present invention, the displacement of the leaf spring is detected by the detector via the branch rod, and the detector is separated from the grip portion having the leaf spring. For example, even if the gripper hits an obstacle,
The detector can be protected from the obstacle.

According to the fifth aspect of the present invention, the tip end of the branch rod can be reliably supported by the support frame so as not to be displaced from the detector.

According to the sixth aspect of the present invention, the detector can be arranged so as not to be bulky along the operation arm, and the detector can be protected from obstacles by the operation arm.

According to the seventh aspect of the present invention, the push-pull force applied to the grip portion and the push-pull direction of the grip portion can be precisely detected by the potentiometer via the branching rod, and the track body can be detected based on the detection signal. It can be moved forward or backward as desired.

[Brief description of the drawings]

FIG. 1 is a side view of a lift truck according to a first embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a side view of the main part.

FIG. 4 is a plan view of the main part.

FIG. 5 is a view as viewed in the direction of arrows BB in FIG. 4;

FIG. 6 is a perspective view of the main part.

FIGS. 7A to 7C are explanatory diagrams illustrating a detection operation.

FIG. 8 is a side view of a main part of a lift truck according to a second embodiment of the present invention.

FIG. 9 is a plan view of the same.

FIG. 10 is a perspective view of the main part.

FIGS. 11A to 11C are explanatory diagrams illustrating a detection operation.

FIG. 12 is a side view showing a conventional example.

FIG. 13 is a plan view of the same.

FIG. 14 is an enlarged plan view of the main part.

15 is a view as viewed in the direction of arrows AA in FIG. 14;

[Explanation of symbols]

 Reference Signs List 3 truck body 7 lift 13 operating arm 17A, 17B potentiometer (detector) 17a potentiometer detection rod 25 gripper 25A leaf spring 25B grip 26 strain gauge (detector) 30 branch rod 30a tip end of branch rod 31 support frame 32 penetration Hole a Forward b Reverse

Claims (7)

[Claims] An operation arm extends rearward from a self-propelled truck body having a lift disposed at a front portion, and the traveling direction of the truck body is changed by swinging the operation arm left and right. In the truck, a grip provided at the tip of the operation arm is formed so as to be elastically displaceable in the front-rear direction, and a detector is provided for detecting the elastic displacement of the grip, and a detection signal of the detector is provided. A lift truck, wherein the truck body is moved forward or backward based on the following. 2. A pair of left and right handles protruding from both sides of a distal end portion of the operation arm, wherein the grip portion has a leaf spring and an elastically displaceable grip externally fitted to the leaf spring. 2. The lift truck according to claim 1, wherein the lift truck is provided between the lift trucks, and the elastic displacement of the leaf spring is detected by a detector. 3. The lift truck according to claim 2, wherein said detector comprises a strain gauge attached to said leaf spring. 4. The lift truck according to claim 2, further comprising a branch rod extending forward from said leaf spring, wherein a displacement of a tip of said branch rod is detected by said detector. 5. The lift truck according to claim 4, wherein a branching rod is supported by a support frame protruding from the operation arm so as to be movable back and forth. 6. The lift truck according to claim 4, wherein the detector is arranged along the operation arm. 7. The lift truck according to claim 4, wherein the detector comprises a potentiometer engaged with a tip of the branch rod.