JPH11139796A - Tilt control device of fork lift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fork-lift tilt control device that is able to tilt a fork into a desired tilt angle. SOLUTION: An operating angle θ1 of a turn knob 22 by an operator 23 is detected by a potentiometer 19 while an actual tilt angle θ2 of a fork 11 is detected by another potentiometer 20 as well, therefore a controller 17 calculates a desired tilt angle conformed to the operating angle θ1, controlling the hydraulic pressure of a tilt cylinder 12 via a solenoid valve 14 and a pumping motor 18, and a tilting quantity of the fork 11 is adjusted till the actual tilt angle θ2 is accorded with the target tilt angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for controlling a tilt operation of a fork in a forklift.

[0002]

2. Description of the Related Art FIG. 5 shows a side view of a conventional forklift 1. The forklift 1 includes a driver's seat 3 at a rear portion of a vehicle body 2 and a mast device 5 at a front portion of the vehicle body 2 for supporting a fork 4 so as to be able to move up and down. The piston rod of the tilt cylinder 6 is connected to the fork 4.
The hydraulic pressure in the tilt cylinder 6 changes according to the operation of a tilt lever 7 provided in the driver's seat 3. As for the relationship between the operation angle of the tilt lever 7 and the tilt operation, as shown in FIG. 6, the more the tilt lever 7 is tilted, the more the stroke speed of the piston rod 6, that is, the tilt speed of the fork 4 increases. I have.

[0003]

However, in the forklift 1 described above, the operator 8 can directly control the tilt lever 7 with the tilt speed of the fork 4, and how many times the fork 4 is inclined with respect to the horizontal direction. It was not such a tilt angle. Therefore, fork 4
Is set to the target tilt angle, the operator 8 actually approaches the fork 4 and adjusts the tilt speed to approach the target tilt angle. However, since the operator 8 views the fork 4 from the driver's seat 3 behind the mast device 5, the tilt angle must be estimated by a slight change in the attitude of the fork 4 viewed from the longitudinal direction of the fork 4.
It was not easy to achieve the desired tilt angle. The present invention has been made to solve such a problem, and an object of the present invention is to provide a tilt control device of a forklift capable of easily setting a fork to a desired tilt angle.

[0004]

In order to achieve the above object, a tilt control device of the present invention detects a tilt operation member operated by an operator to tilt a fork and an operation amount of the tilt operation member. An operation amount sensor, a tilt amount sensor for detecting a tilt amount of the fork, a fork tilt mechanism for tilting the fork, and a target tilt amount are calculated from the operation amount detected by the operation amount sensor, and the target tilt amount and the tilt amount are calculated. So that the tilt amount detected by the sensor matches
And a controller for controlling the fork tilt mechanism.

[0005] The tilt operating member can be attached to an elevating lever for operating the fork up and down. In this case, the tilt operation member can be constituted by a knob that rotates in substantially the same direction as the operation direction of the elevating lever. Alternatively, a grip member having a lift operation lever and a reach operation lever for an operator to perform a lift operation and a reach operation of a fork with a finger is formed in a driver's seat of a forklift, and the tilt operation member is rotated by another finger. It may be a rotary knob provided on the grip member so that it can be performed. It is preferable that the tilt operation member be provided with a mechanism indicating an operation position at which the fork is horizontal. Further, a potentiometer may be used as each of the operation amount sensor and the tilt amount sensor.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Embodiment 1 FIG. FIG. 1 conceptually shows a tilt control device according to Embodiment 1 of the present invention. A piston rod 13 of a tilt cylinder 12 forming a fork tilt mechanism is connected to a rear portion of the fork 11. The piston rod 13 strokes due to a difference in hydraulic pressure acting before and after the piston. The cylinder chamber of the tilt cylinder 12 is connected to an oil tank 16 via an electromagnetic valve 14 and a pump 15. The opening and closing of the electromagnetic valve 14 is controlled by a controller 17. Pump 15
A pump motor 18 whose rotation speed is controlled by a controller 17 is connected. Further, the controller 17 includes potentiometers 19 and 20 and a battery 2.
1 is connected.

[0007] The potentiometer 19 is connected to a rotary knob 22 provided in the driver's seat.
, The amount of rotation of the rotary knob 22 is detected. This rotation amount is detected as an operation angle θ1 from a neutral position which is a predetermined origin. Therefore, the rotary knob 22
Is in the neutral position, it means that the operation angle θ1 is 0 degrees. On the other hand, the potentiometer 20 is provided on the tilt axis C of the fork 11, and the fork 1
The tilt angle such as how many times 1 is tilted upward or downward from the horizontal direction can be detected as the tilt angle θ2.

As shown in FIG. 2, the relationship between the operation angle θ1 detected by the potentiometer 19 and the corresponding target tilt angle θ3 is stored in the controller 17 in advance. When the operation angle θ1 is input, the controller 17 calculates a target tilt angle θ3 based on the relationship in FIG. As an example of the present embodiment, when the operation angle θ1 is 20 degrees, the target tilt angle θ3 is 2 degrees, and when the operation angle θ1 is 0 degrees, that is, when the operation angle θ1 is at the neutral position, the target tilt angle θ3 is 0 degrees. The degree is calculated.

In the tilt control device having the above configuration, when the operator 23 turns the rotary knob 22, the operation angle θ1 is detected by the potentiometer 19, and the controller 17 calculates the target tilt angle θ3 corresponding thereto. The controller 17 includes the fork 11
To the target tilt angle θ3.
The desired hydraulic pressure is adjusted by adjusting the rotation speed of the tilt cylinder 12.
To act on. Thereby, the piston rod 1
3 strokes and the fork 11 tilts.

The actual tilt angle θ2 of the fork 11 is detected by a potentiometer 20 and
7, the controller 17 further adjusts the rotation speed of the pump motor 18 based on the result so that the difference Δθ between the target tilt angle θ3 and the actual tilt angle θ2 is eliminated. Also, the controller 17
Depending on whether the difference Δθ between the target tilt angle θ3 and the actual tilt angle θ2 is plus or minus, the electromagnetic valve 1 changes the flowing direction of the oil and changes the moving direction of the piston rod 13.
Switch the oil path of 4. When the difference Δθ between the target tilt angle θ3 and the actual tilt angle θ2 becomes 0, the pump motor 18 is stopped by the controller 17, the oil passage of the electromagnetic valve 14 is closed, and the desired tilt angle of the fork 11 Is obtained. As described above, in this embodiment, since the operator 23 only needs to turn the rotary knob 22 provided in the driver's seat to a position where a desired tilt angle can be obtained, the target tilt angle can be intuitively and easily understood. Can be obtained.

Embodiment 2 Rotation knob 22 and potentiometer 19 of tilt control device according to Embodiment 1
May be provided on the grip portion 25 of the elevating lever 24 for controlling the elevating of the fork 11 as shown in FIG.
The elevating lever 24 can be tilted in the front-rear direction of the machine stand, and when tilted forward as shown by an arrow D in the figure, the fork 11
Is lowered, and when the fork 11 is tilted rearward as shown by an arrow U in the figure, the fork 11 is raised. The rotary knob 22 is provided at the grip 25 by an operator 23.
A part of the circumferential surface of the rotary knob 22 is exposed in an arc shape from the surface of the grip 25 so that the operator 23 can turn only the thumb. The rotation direction of the rotary knob 22 is substantially the same as the operation direction of the elevating lever 24 and can be rotated in the front-back direction of the machine base.
When the fork 11 is turned forward as shown by the arrow F in the figure, the fork 11 tilts downward, and when it is turned backward as shown by the arrow R in the figure, the fork 11 tilts upward.
In addition, concave portions 26 and 27 are formed in the rotary knob 22 and the grip portion 25 to indicate to the operator 23 the position where the fork 11 is horizontal. Recess 26
Is aligned with the concave portion 27 of the grip portion 25 when the rotary knob 22 is at the neutral position, and forms a hemispherical concave portion together with the concave portion 27.

With the above-described configuration, the operator 23 can simultaneously perform the lifting operation of the fork 11 and the tilt operation of the fork 11 with one hand, and can smoothly perform a series of cargo handling operations without holding the lever. can do. Moreover, since the tilting direction of the elevating lever 24 and the rotating direction of the rotary knob 22 are substantially the same, a more intuitive tilt operation feeling without confusion for the operator 23 is obtained. Furthermore, fork 11
Is horizontal, the rotary knob 22 may be turned so as to form a hemispherical depression by the concave portion 26 and the concave portion 27.

Embodiment 3 In the tilt control device according to the first embodiment, as shown in FIG. 4, a grip member 28 gripped by an operator 23 is attached to a driver's seat, and the grip member 28 is used to perform a lifting operation and a reach operation of the fork 11, respectively. A lifting operation lever 29 and a reach operation lever 30 to be performed, and a rotary knob 22 for performing a tilt operation of the fork 11 may be provided. The grip member 28 is provided with two shaft members 32 and 33 provided in parallel with a certain gap 31 substantially in the front-rear direction of the machine frame, and attached to both ends of the shaft members 32 and 33, and both are integrally formed. It is mainly composed of a pair of plates 34 and 35 to be connected.

An elevating operation lever 29 and a reach operation lever 30 are juxtaposed at one end of the shaft member 32 located forward of the shaft members 32, 33. The elevating operation lever 29 and the reach operation lever 30 are provided so that the operator 23 can operate with only the index finger and the middle finger, respectively. On the other hand, a rotation knob 22 is provided on one end side of the shaft member 33 located rearward so that the operator 23 can turn the thumb member only with the thumb. With such a configuration, the operator 23 can simultaneously perform the lifting / lowering operation, the reach operation, and the tilt operation of the fork with one hand, and can smoothly perform a series of cargo handling operations without holding the lever.

The ring finger and the little finger that do not operate the operation levers 29 and 30 and the rotary knob 22 have two shaft members 3.
It can be inserted into the gap 31 formed between the members 2 and 33, and more precise operation can be performed by operating the operation levers 29 and 30 and the rotary knob 22 while grasping the rear shaft member.

Embodiment 4 In the tilt control device according to the first embodiment, a mechanism for indicating the position where the fork 11 becomes horizontal to the operator 23 may be provided on the rotary knob 22. Specifically, the operation angle θ1 of the rotary knob 22 is 0.
A click mechanism is provided so that a click sensation is generated on the rotary knob 22 at the neutral position. Accordingly, when the fork 11 is to be horizontal, for example, when the fork 11 is inserted into or removed from a pallet on which a load is placed, the operator 23 may turn the rotary knob 22 depending on a click feeling, and the operation angle θ1 is 0 degree. The position of is easily understood. That is, the fork 11 can be more easily and reliably leveled.

Embodiment 5 Instead of directly detecting the tilt angle of the fork 11 by the potentiometer 20, a stroke sensor for detecting the stroke amount of the piston rod 13 of the tilt cylinder 12 is used to calculate the tilt angle θ2 of the fork 11 from the stroke amount of the piston rod 13. It may be.

Embodiment 6 FIG. The rotary knob 22 may be provided on a lever other than the elevating lever 24, for example, a traveling lever for operating the forklift to move forward and backward. In this case, the operator 23 can perform the tilt operation of the fork 11 with one hand while performing the forward and backward operation of the forklift.

In the first to sixth embodiments, as a method of controlling the hydraulic pressure acting on the tilt cylinder 12, instead of adjusting the rotation speed of the pump motor 18 connected to the pump 15, a proportional electromagnetic valve is used. Alternatively, the hydraulic pressure may be controlled by the degree of opening and closing of the proportional electromagnetic valve. Further, instead of the mechanism for tilting the fork 11 by changing the hydraulic pressure of the tilt cylinder 12 as described above, a rotating shaft of a motor is connected to the fork 11 via a suitable speed reducing means, and the rotation of the motor causes the fork 11 to tilt. It may be a mechanism to make it. In this case, the controller 17 considers the difference Δθ between the target tilt angle θ3 and the actual tilt angle θ2 and
To control the rotation of the motor connected to.

[0020]

As described above, according to the tilt control device of the present invention, the operator only needs to operate the tilt operating member to a position where a desired tilt angle can be obtained. The fork can be easily set to the target tilt angle.

Further, by attaching the tilt operating member to an elevating lever for operating the elevating and lowering of the fork, the operator can simultaneously perform the fork elevating operation and the tilt operation with one hand. Furthermore, by making the tilt operation member a knob that rotates in substantially the same direction as the operation direction of the elevating lever, a more intuitive tilt operation feeling can be obtained.

Further, the tilt operation member is provided on the grip member together with the elevation operation lever and the reach operation lever for performing the elevation operation and the reach operation of the fork, so that the operator can perform the elevation operation, the reach operation and the tilt operation of the fork. Can be done simultaneously with one hand.

By providing the tilt operation member with a mechanism indicating the operation position at which the fork is horizontal, the operator can easily level the fork. If a potentiometer is used as each of the operation amount sensor and the tilt amount sensor, the operation amount of the tilt operation member and the tilt amount of the fork can be converted into electric signals and input to the controller, thereby facilitating arithmetic processing in the controller.

[Brief description of the drawings]

FIG. 1 is a diagram conceptually showing a tilt control device according to a first embodiment of the present invention.

FIG. 2 is a view showing a relationship between an operation angle θ1 of a rotary knob and a target tilt angle θ3 corresponding thereto in the tilt control device according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a tilt control device according to a second embodiment of the present invention, showing a lifting lever provided with a rotary knob.

FIG. 4 is a perspective view of a grip member provided with a rotary knob, a lifting operation lever, and a reach operation lever in the tilt control device according to Embodiment 3 of the present invention.

FIG. 5 is a side view of a conventional forklift.

FIG. 6 is a diagram showing a relationship between a tilt lever angle and a tilt speed in a conventional forklift.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Fork 12 Tilt cylinder 13 Piston rod 14 Electromagnetic valve 15 Pump 17 Controller 18 Pump motor 19, 20 Potentiometer 22 Rotary knob 23 Operator 24 Elevating lever 26, 27 Depression 28 Grip member 29 Elevating operation lever 30 Reach operation lever

Claims (6)

[Claims] A tilt operation member operated by an operator to tilt the fork; an operation amount sensor for detecting an operation amount of the tilt operation member; a tilt amount sensor for detecting a tilt amount of the fork; A fork tilt mechanism for tilting, a target tilt amount is calculated from the operation amount detected by the operation amount sensor, and the target tilt amount is calculated so that the target tilt amount matches the tilt amount detected by the tilt amount sensor. A tilt control device for a forklift, comprising a controller for controlling a fork tilt mechanism. 2. The tilt control device according to claim 1, wherein the tilt operation member is attached to an elevating lever that operates to elevate the fork. 3. The tilt control device according to claim 2, wherein the tilt operation member is a knob that rotates in substantially the same direction as the operation direction of the lift lever. 4. A grip member provided with a lift operation lever and a reach operation lever for an operator to perform a lift operation and a reach operation of the fork by a finger, respectively, is formed in a driver's seat of the forklift. The tilt control device according to claim 1, wherein the operation member is a rotation knob provided on the grip member so that the operation member can be rotated by another finger. 5. The tilt control device according to claim 1, wherein the tilt operation member is provided with a mechanism indicating an operation position at which the fork is horizontal. 6. The tilt control device according to claim 1, wherein each of the operation amount sensor and the tilt amount sensor is a potentiometer.