JP2000302396A - Control device of cargo handling cylinder of forklift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the operational delay of a lift cylinder when a lift lever is suddenly operated. SOLUTION: In a control device of a cargo handling cylinder for a forklift truck comprising a hydraulic pump 2 for discharging the working oil, a pump motor 3 for operating the pump 2, a proportional solenoid valve 5 to regulate the flow rate of the working oil to be discharged from the pump 2 and supply the desired flow rate to a lift cylinder 4, and a controller 6 to output the drive signal to the pump motor 3, control the drive of the pump motor 3, output the command signal based on the operational quantity of a lift lever 7 to the proportional solenoid valve 5, and control the operation of the proportional solenoid valve 5, is provided with a potentiometer 10 for detecting the operational speed of the lift lever 7, and when the operational speed of the lift lever 7 is judged to be excessively rapid compared with the operational speed of the lift lever 7 detected by the potentiometer 10 in the controller 6, the command signal based on the manipulated variable of the lift lever 7 to be outputted to the proportional solenoid valve 5 is increased and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling a cargo handling cylinder such as a lift cylinder for raising and lowering a fork, a tilt cylinder for tilting a mast, and other attachment cylinders in a forklift truck.

[0002]

2. Description of the Related Art Conventionally, a forklift truck has a working machine mounted on a vehicle body. The working machine includes a mast which can be tilted back and forth by a tilt cylinder at a front portion of the vehicle body, and a lift cylinder along the mast. And a lift bracket that can be moved up and down by a chain. The lift bracket is provided with a fork.

In a forklift truck equipped with such a working machine, for example, as a control device for a lift cylinder as a cargo handling cylinder, as shown in FIG. 1, a hydraulic pump 2 for discharging hydraulic oil from a hydraulic tank 1 is used. When,
A pump motor 3 for driving the hydraulic pump 2 is provided, and a proportional solenoid valve 5 for regulating a flow rate of hydraulic oil discharged from the hydraulic pump 2 and supplying a desired flow rate to the lift cylinder 4 is provided.

The proportional solenoid valve 5 moves the spool by the solenoid A and the solenoid B based on the input command signal, and moves at the ascending position U, the stop position N, and the descending position D, and the hydraulic oil flows. The lift, the stop and the lowering of the lift cylinder 4 are performed by changing the flow rate of the hydraulic oil by changing the direction and the valve opening.

The solenoids A and B are connected to a controller 6 mounted on the vehicle body, and are controlled by receiving a command signal from the controller 6. The controller 6 is connected to a lift lever 7 which is an operation lever installed in a cab of a vehicle body, inputs an operation direction and an operation amount of the lift lever 7, and outputs a drive signal to the pump motor 3. And controls the operation of the proportional solenoid valve 5 by outputting a command signal to the solenoid A or the solenoid B based on the operation amount of the lift lever 7.

In the control device for the lift cylinder 4 as described above, when the lift lever 7 is operated as shown in FIG. 2, when the lift lever 7 comes out of the neutral region, a drive signal is output to the pump motor 3 and , Proportional solenoid valve 5
A command signal based on the operation amount of the lift lever 7 is output. The inclination of the command signal output to the proportional solenoid valve 5 based on the operation amount of the lift lever 7 changes in accordance with the operation amount of the lift lever 7, that is, the greater the operation amount of the lift lever 7, the steeper the inclination. Had become. In order to prevent the occurrence of a large shock at the time of startup in the lift cylinder 4 when the lift lever 7 is suddenly operated, the command signal is restricted so as not to exceed a predetermined inclination which is a maximum inclination. And this pump motor 3
In the actual operation of the lift cylinder 4, the actual operation of the pump motor 3 is slightly delayed from the drive signal due to the rise delay, so that the actual operation of the lift cylinder 4 is controlled by a command signal from the proportional solenoid valve 5. From the position S which is slightly delayed from the rise.

[0007]

In such a conventional control device for a lift cylinder, which is a loading cylinder of a forklift truck, a lift lever 7 as an operation lever is provided.
Is operated suddenly, as shown in FIG.
Outputs a drive signal to the pump motor 3 when the motor comes out of the neutral region, and outputs a command signal to the proportional solenoid valve 5 which is the maximum inclination based on the operation amount of the lift lever 7. Since the actual driving of the motor 3 is slightly delayed from the drive signal due to the rise delay, a desired flow rate of the hydraulic oil is not supplied from the pump motor 3 to the proportional solenoid valve 5, and the lift lever 7 Even when the valve opening degree is based on the operation amount, the position S of the lift cylinder 4 at which the lift cylinder 4 actually operates is greatly delayed due to the insufficient flow rate of the hydraulic oil. That is, there has been a problem that the operation of the lift cylinder 4 after the operation of the lift lever 7 actually starts (operates) is greatly delayed. When the lift lever 7, which is the operation lever, is operated normally, as shown in FIG.
When the lift cylinder 4 is actually operated, the rise delay of the pump motor 3 is eliminated when the lift cylinder 4 is actually operated, and the above-described problem occurs when the lift lever 7 is suddenly operated. Absent.

As described above, when the lift lever 7 is suddenly operated, the movement of the lift cylinder 4 is inevitably greatly delayed. When performing the operation, the lift lever 7 is suddenly operated,
As described above, when the actual operation of the lift cylinder 4 is greatly delayed, the operation responsiveness may be extremely poor, or a feeling at the time of operation may be uncomfortable.
Actually, a problem that the inching operation cannot be performed may occur. An object of the present invention is to solve these problems.

[0009]

According to a first aspect of the present invention, there is provided a hydraulic pump for discharging working oil, and a pump motor for driving the hydraulic pump. Equipped with a proportional solenoid valve that supplies the flow rate of the work to the cargo handling cylinder in the work machine, outputs a drive signal to the pump motor to control the drive of the pump motor, and sends a command signal based on the operation amount of the operating lever to the proportional solenoid valve A control device for a loading cylinder of a forklift truck provided with a controller for outputting and controlling the operation of a proportional solenoid valve, comprising: an operating speed detecting means for detecting an operating speed of an operating lever; If it is determined that the operating speed of the operating lever is abrupt based on the operating speed of the operating lever detected in step 2, the operation output to the proportional solenoid valve is performed. And it outputs the increased command signal based on the operation amount of the lever.

In a second aspect based on the first aspect, the controller further comprises a load detecting means for detecting a load on the work implement, and the controller outputs to the proportional solenoid valve in accordance with the load detected by the load detecting means. The amount of increase of the command signal based on the operation amount of the lever is changed.

[0011]

According to the first aspect of the invention, when the cargo handling lever is suddenly operated, the valve opening of the proportional solenoid valve becomes larger than the normal valve opening, and a desired flow rate can be supplied to the cargo handling cylinder. As a result, it is possible to prevent the actual operation of the cargo handling cylinder from being greatly delayed.

According to the second aspect of the invention, the loading cylinder can always be operated substantially constantly without being affected by the load on the fork, so that the operator can feel the same feeling in any state. Can be operated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control device for a loading cylinder of a forklift truck according to the present invention will be described. A work machine having a mast that can be tilted back and forth by a tilt cylinder at the front of a vehicle body, a lift bracket that can be moved up and down by a lift cylinder and a chain along the mast, and a fork mounted on the lift bracket In a forklift truck equipped with, as a control device for a lift cylinder, which is a type of cargo handling cylinder, as shown in FIG.
A hydraulic pump 2 for discharging hydraulic oil from a hydraulic tank 1 and a pump motor 3 for driving the hydraulic pump 2 are provided. The flow rate of hydraulic oil discharged from the hydraulic pump 2 is regulated to supply a desired flow rate to the lift cylinder 4. The proportional solenoid valve 5 is provided.

The proportional solenoid valve 5 moves a spool by a solenoid A and a solenoid B based on an input command signal, so that a rising position U at which hydraulic oil is supplied to the bottom 4a side of the lift cylinder 4; Position N at which the flow of air is interrupted, the bottom 4 of the lift cylinder 4
The hydraulic cylinder moves at the lowering position D where the hydraulic oil flows from the a side to the hydraulic tank 1. By changing the flow direction of the hydraulic oil and the flow rate of the hydraulic oil by changing the valve opening, the lift in the lift cylinder 4 is increased. Stop and descend.

The solenoids A and B are connected to a controller 6 mounted on the vehicle body, and are controlled by receiving a command signal from the controller 6. The controller 6 is connected to a potentiometer 10 which is a lever detecting means attached to a lift lever 7 which is an operation lever installed in a driver's cab of the vehicle body. The operation direction and the operation amount of the lift lever 7 are controlled by the potentiometer 10. Is input, thereby outputting a drive signal to the pump motor 3 to control the drive of the pump motor 3 and
A command signal is output to the solenoid A or the solenoid B based on the operation amount of the lift lever 7 to control the operation of the proportional solenoid valve 5.

An operating speed detecting means for detecting the operating speed of the lift lever 7 is provided. As the operating speed detecting means, the potentiometer 10 mounted on the lift lever 7 is used. The operation speed is calculated based on the change.

In the control device for the cargo handling cylinder, when the lift lever 7 is operated by the controller 6, the lift motor 7 is operated by the pump motor 3 when the lift lever 7 comes out of the neutral region. A drive signal based on the amount is output, and a command signal based on the operation amount of the lift lever 7 is output to the proportional solenoid valve 5.

On the other hand, the controller 6 inputs the operation speed of the lift lever 7 from a potentiometer 10 as operation speed detecting means, and determines whether or not the operation speed of the lift lever 7 is a sudden operation. This is lift lever 7
Calculates the operation speed from the operation amounts of the plurality of lift levers 7 detected at a time in the early stage of the operation immediately before the vehicle exits the neutral region, and determines that the operation is sudden if the operation speed is faster than a preset speed. It is. And lift lever 7
When the controller 6 determines that the operation speed is abrupt, the controller 6 outputs a drive signal based on the operation amount of the lift lever 7 to the pump motor 3 in the same manner as in the normal state, and also sends the lift lever to the proportional solenoid valve 5. A command signal based on the manipulated variable of No. 7 is output after being increased from a normal value. this is,
The valve opening of the proportional solenoid valve 5 is made larger than a normal valve opening so as to compensate for a shortage of the flow rate of hydraulic oil in the proportional solenoid valve 5 due to a delay in rising of the pump motor 3 at the time of sudden operation. In order to obtain a command signal to be output to the proportional solenoid valve 5 to increase the degree, the normal command signal K0 is calculated from an arithmetic expression indicating a command signal for the operation amount of the lift lever 7 in a normal state shown in FIG. (K0 + α) and outputs to the proportional solenoid valve 5 an initial command signal K1 which is larger than the normal time. Then, a coefficient β is added to the obtained initial command signal K1 (K
1 + β), and thereafter, the previously output command signal Kn-1
Is added (Kn-1 + β). In addition,
Instead of adding the coefficient β, the previously output command signal Kn
−1 may be multiplied by a coefficient β (Kn−1 × β). As a result, the proportional solenoid valve 5 supplies a desired flow rate to the lift cylinder 4 by increasing the valve opening even if the flow rate of the hydraulic oil is insufficient due to a delay in rising of the pump motor 3.

When the lift lever 7 is suddenly operated, the pump motor 3 is operated by the pump motor 3 when the lift lever 7 comes out of the neutral region, as shown in FIG. In addition to outputting a drive signal based on the amount, a command signal based on the operation amount of the lift lever 7 is output to the proportional solenoid valve 5 in a manner larger than a normal value. At this time, the actual drive of the pump motor 3 is slightly delayed from the drive signal due to the rise delay, but by setting the valve opening of the proportional solenoid valve 5 larger than the normal valve opening, the lift cylinder A desired flow rate is supplied to the lift cylinder 4 so that the actual movement (operation) of the lift cylinder 4 is not greatly delayed from the start of the operation of the lift lever 7.

In this way, even if the lift lever 7 is suddenly operated to perform, for example, an inching operation, the actual operation of the lift cylinder 4 is not significantly delayed.
Thereby, the operation responsiveness of the lift lever 7 can be improved and the feeling of discomfort during the operation can be eliminated, and the inching operation can be performed satisfactorily.

In order to eliminate the delay in the rise of the pump motor 3, there is a control of driving the pump motor 3 earlier in advance. However, such a control imposes a heavy load on the circuit. Although there was a possibility that the cost would increase due to the increase in the capacity, the problem of the rising delay of the pump motor 3 is eliminated as described above, thereby eliminating the cost increase of the circuit and the like.

Next, a description will be given of another embodiment of the control device for a loading cylinder of a forklift truck according to the present invention. The control device of the lift cylinder is substantially the same as that of the above-described embodiment, but is slightly different in the following points. That is, as shown in FIG. 6, in the above-described embodiment, a load detecting means for detecting the load on the lift cylinder 4, that is, the load on the work implement, is further provided near the lift cylinder 4. The load detecting means is a pressure sensor 11, and the load is detected by detecting the pressure applied to the lift cylinder 4 by the pressure sensor 11. This load is specifically the load on the fork. The pressure sensor 11 is also connected to the controller 6, and the load of the lift cylinder 4 detected by the pressure sensor 11 is input to the controller 6. When the controller 6 determines that the operation speed of the lift lever 7 is a sudden operation, the controller 6 sends the lift lever 7 to the proportional solenoid valve 5.
A command signal based on the manipulated variable is output after being increased from a normal value. The amount of increase in the command signal at this time is changed in accordance with the load detected by the pressure sensor 11, and the valve opening is set to In order to obtain a command signal to be output to the proportional solenoid valve to increase the value, first, as described above, a normal command signal K0 is calculated from an arithmetic expression indicating a command signal for the operation amount of the lift lever 7 in a normal state. Add initial coefficient α (K0
+ Α) to obtain an initial command signal K1 that is larger than the normal time and output to the proportional solenoid valve 5. The initial coefficient α at this time is
As shown in FIG. 7, the value is changed according to the load so that the initial coefficient α is small when the load is small and the initial coefficient α is large when the load is large. Then, the obtained initial command signal K
1 is added to the coefficient β (K1 + β), and thereafter, the coefficient β is added to the previously output command signal Kn−1 (Kn−1).
+ Β). At this time, as shown in FIG. 8, the coefficient β is changed according to the load such that the coefficient β is large when the load is small and the coefficient β is small when the load is large.
The feeling according to the load is obtained. Note that, similarly to the above, instead of adding the coefficient β, the previously output command signal Kn−1 is multiplied by the coefficient β (Kn−
1 × β).

Thus, the command signal based on the operation amount of the lift lever 7 output to the proportional solenoid valve 5 when the lift lever 7 is suddenly operated is changed and output according to the load, so that the lift cylinder 4 The operation is always substantially constant without being affected by the load on the fork.

In this manner, the actual operation of the lift cylinder 4 is prevented from being greatly delayed, and the operational response of the lift lever 7 is improved, and the feeling of operation is improved. Eliminating discomfort, performing good inching operation, and
The lift cylinder 4 can be operated almost constantly without being affected by the load on the fork, and the operator can always operate with the same feeling regardless of the load on the fork. Can be reduced.

In each of the embodiments described above, the case where the lift cylinder 4 is used as the cargo handling cylinder is described. However, the present invention is not limited to this, and the tilt cylinder for tilting the mast and other attachment cylinders are used. Cylinder or the like.

[0026]

When the controller determines that the operation speed of the operation lever is abrupt, the command signal based on the operation amount of the operation lever to be output to the proportional solenoid valve is increased and output, thereby increasing the load handling lever. When suddenly operated, the valve opening of the proportional solenoid valve becomes larger than the normal valve opening,
A desired flow rate can be supplied to the cargo handling cylinder, thereby preventing the actual operation of the cargo handling cylinder from being greatly delayed, thereby improving the operational response of the operation lever and eliminating a feeling of discomfort during operation. be able to. Also, by changing the amount of increase of the command signal based on the operation amount of the operation lever output to the proportional solenoid valve according to the load in the controller, the loading cylinder is always substantially constant without being affected by the load on the fork. Can be operated, whereby the operator can operate with the same feeling in any state, and the operation can be facilitated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control device for a loading cylinder of a forklift truck.

FIG. 2 is a chart for explaining an operation state of a conventional control device for a cargo handling cylinder.

FIG. 3 is a chart for explaining an operation state in a conventional control device for a cargo handling cylinder.

FIG. 4 is a table of an arithmetic expression showing a command signal for a normal operation amount of the lift lever according to the present invention.

FIG. 5 is a table for explaining an operation state in the control device for the cargo handling cylinder according to the present invention.

FIG. 6 is a configuration diagram of a control device of a loading cylinder of another forklift truck.

FIG. 7 is a table showing a relationship between a load and an initial coefficient.

FIG. 8 is a chart showing a relationship between a load and a coefficient.

[Explanation of symbols]

1 ... Hydraulic tank, 2 ... Hydraulic pump, 3 ... Pump motor,
4 lift cylinder, 4a bottom, 5 proportional solenoid valve
6: controller, 7: lift lever, 10: potentiometer, 11: pressure sensor.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ikuo Hayama 110 Yokokura Nitta, Koyama City, Tochigi Pref.

Claims (2)

[Claims] A hydraulic pump (2) for discharging working oil and a pump motor (3) for driving the hydraulic pump (2) are provided. A proportional solenoid valve 5 for supplying to the loading cylinder is provided. A drive signal is output to the pump motor 3 to control the drive of the pump motor 3 and a command signal is output to the proportional solenoid valve 5 based on the operation amount of the operation lever. And a controller for controlling the operation of the proportional solenoid valve 5 for controlling the operation of the proportional solenoid valve 5. The control device for a loading cylinder of a forklift truck includes operation speed detection means for detecting an operation speed of an operation lever. When it is determined that the operation speed of the operation lever is abrupt operation from the operation speed of the operation lever detected by the means, the proportional solenoid valve 5
A command signal based on an operation amount of an operation lever to be output to the controller, and outputs the command signal in an increased manner. 2. A command based on an operation amount of an operation lever output to the proportional solenoid valve 5 in accordance with the load detected by the load detection means in the controller 6 and provided with load detection means for detecting a load on the work machine. 2. The control device according to claim 1, wherein the amount of increase of the signal is changed.