JPH11336703A - Control device for hydraulic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability and reduce energy consumption, and to prevent rise in temperature, occurrence of leakage or deterioration of lubricating property by controlling the number of rotations of an electric motor depending on operating amount of a control lever or oil pressure of a hydraulic pump. SOLUTION: This control device for hydraulic equipment comprises an electric motor 6, a fixed-displacement type hydraulic pump 7 connected to the electric motor 6, a cylinder 11 connected to the hydraulic pump 7, a control lever 18 for operating the hydraulic pump 7 through the electric motor 6. The control device further comprises an operating amount detecting means 21 for detecting the operating amount of a control member which controls the number of rotations of the electric motor 6 according to a detected value by the operating amount detecting means 21. The control device control an injection amount of hydraulic oil from the hydraulic pump 7 according to a detection value of the means 21. A rod 12 of the cylinder 11 is provided with a limit stroke detecting means 23 to control the number of rotations of the electric motor 6 when the rod 12 is in a limit stroke state, thus reducing an injection amount or stopping the injection.

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 various hydraulic devices having a hydraulic drive mechanism such as a hydraulic shovel and a lift for carrying heavy objects.

[0002]

2. Description of the Related Art This type of hydraulic equipment includes an electric motor, a hydraulic pump driven by the electric motor, and a cylinder connected to the hydraulic pump. The hydraulic oil in the storage tank is supplied to the cylinder, and the rod of the cylinder moves forward and backward.

At this time, the spool position of the control valve is switched by operating a control lever to advance or retract the rod of the cylinder. Further, when the control lever is in a neutral position, the hydraulic oil discharged from the pump is directly bypassed to the tank.

Here, the discharge amount of hydraulic oil discharged from the pump is proportional to the rotation speed of the electric motor. The discharge amount increases when the rotation speed is high, and decreases when the rotation speed is low. . Also, if the amount of discharge per unit time sent to the cylinder is large, the advance speed of the cylinder rod is high,
If the discharge amount is small, the advance speed of the cylinder rod becomes slow.

[0005]

However, in the above-mentioned hydraulic equipment, the amount of operation of the control lever by which the driver switches the direction of movement of the cylinder rod and performs the stop operation is reduced.
It is irrelevant to the rotation speed of the electric motor (discharge amount from the pump). As a result, the cylinder rod moves rapidly immediately after the start of the operation of the control lever, or conversely, the lever cannot be moved quickly even if the lever operation amount is increased. There was a problem that was bad.

Further, in the conventional hydraulic equipment, even if the rod of the cylinder reaches the limit stroke, the hydraulic oil is continuously discharged from the hydraulic pump as long as the operator operates the control member, and the relief valve is operated. Circulates through the oil sump tank to waste power. In addition, when the operating oil is circulated through the relief valve, the energy (flow rate × pressure) is entirely converted into heat, so that the oil temperature increases. And when the oil temperature becomes high,
Problems occur such as leakage and poor lubricity.

Therefore, in the present invention, the number of rotations of the electric motor is controlled in accordance with the operation amount of the control member or the operation state of the actuator such as a cylinder, and the discharge amount of hydraulic oil from the hydraulic pump is controlled. In addition to improving workability, it also saves energy by eliminating wasteful power consumption, prevents the temperature of the hydraulic oil from rising, and prevents leakage and poor lubricity. .

[0008]

Means for Solving the Problems In order to solve the above problems, a control device for hydraulic equipment, which is a first means of the present invention, comprises:
A control device for a hydraulic device, comprising: an electric motor, a fixed displacement hydraulic pump connected to the electric motor, a cylinder connected to the hydraulic pump, and a control member for operating the hydraulic pump via the electric motor. , An operation amount detection means for detecting an operation amount of the control member is provided, and a discharge amount of hydraulic oil from the hydraulic pump is controlled by controlling a rotation speed of the electric motor according to a value detected by the operation amount detection means. It is intended to be adjusted.

Specifically, in the first means, when the operation amount of the control member detected through the operation amount detecting means is large, the rotation speed of the electric motor is increased, and the hydraulic oil is supplied from the hydraulic pump. By increasing the discharge amount, the moving speed of the rod of the cylinder is increased. Conversely, when the operation amount of the control member is small, the moving speed of the rod of the cylinder is reduced by decreasing the rotation speed of the electric motor and decreasing the discharge amount of the hydraulic oil from the hydraulic pump.

According to the control device for hydraulic equipment as the first means, when the operator wants to operate the hydraulic equipment quickly, he or she wants to increase the operation amount of the control member and to operate it slowly for fine adjustment. In this case, the operation amount may be reduced. That is, the operator can operate the rod of the cylinder as desired by adjusting the operation amount of the control member according to the work situation.

The control device for a hydraulic device as the second means includes an electric motor, a fixed displacement hydraulic pump connected to the electric motor, a cylinder connected to the hydraulic pump, and the electric motor. And a control member for operating the hydraulic pump through the control device, wherein a limit stroke detecting means is provided on the rod of the cylinder, and the rotation speed of the electric motor is controlled when the rod reaches the limit stroke. The discharge amount from the hydraulic pump is adjusted.

For example, when the limit stroke of the rod is detected by the limit stroke detecting means, the rotation of the electric motor is stopped or the number of rotations is reduced.

According to the control device for hydraulic equipment as the second means, the hydraulic pump is disposed so as to detect a state in which the rod of the cylinder as the actuator has reached the limit stroke. It is possible to prevent unnecessary working oil from continuing to be discharged, suppress unnecessary power consumption, and prevent the working oil from rising in temperature.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a hydraulic excavator 1 which is a hydraulic device to which the control device of the present invention is applied. The hydraulic excavator 1 includes a boom 3A protruding from the upper swing body 2, an arm 3B connected to a tip of the boom 3A,
The bucket 4 attached to the tip of B is operated by a rod 12 of a cylinder 11 constituting the hydraulic mechanism 5 shown in FIG.

As shown in FIG. 2, the hydraulic mechanism 5 generally includes an electric motor 6, a hydraulic pump 7, a control valve 9,
The cylinder 11 and a lever (hereinafter, referred to as a control member)
Called control lever. ) A conventional hydraulic device equipped with 18 includes an operation amount detector 21 and a limit stroke detector 2.
3 to control the number of revolutions of the electric motor 6 via the control circuit 24 in accordance with these detected values.

The output shaft of the electric motor 6 is connected to a drive member of a hydraulic pump 7.

The hydraulic pump 7 sucks and discharges hydraulic oil in the oil reservoir tank 8, and has a discharge port provided with a pipe 19a.
Is connected. The pipe 19a is branched in two directions on the way, one of which is connected to a first port 10a of a control valve 9 described later via a check valve 25, and the other is connected to the oil reservoir tank 8 via a relief valve 20. Have been.

The control valve 9 is, for example, a direct link type three-position switching valve, and its position (A, B, B) is controlled by a control lever 18 described later.
C) is switched.

The cylinder 11 has a rod 12 having a piston 13 movably close to the inner wall thereof,
The inside is partitioned into a first liquid chamber 14 and a second liquid chamber 15 by the piston 13. The tip of the rod 12 is connected to the boom 3A, the arm 3B or the bucket 4 of the shovel car 1.

The control lever 18 switches the position (A, B, C) of the control valve to advance, retreat, or stop the cylinder. Specifically, when the control lever 18 is in the neutral position, the control valve 9 is set to the position B as shown in FIG.
And the third port 10c are blocked, and the hydraulic oil discharged from the hydraulic pump 7 is bypassed to the tank 8,
It prevents the hydraulic oil from flowing out of the cylinder 11 and prevents the piston 13
Hold the position of. When the control lever 18 is tilted in the X direction, the control valve 9 switches to the position A, and the hydraulic oil discharged from the hydraulic pump 7 is supplied to the cylinder 11.
The rod 12 of the cylinder 11 is advanced by supplying the liquid to the first liquid chamber 14. Further, when the control lever 18 is tilted in the Y direction, the control valve 9 is switched to the C position, and the hydraulic oil discharged from the hydraulic pump 7 is supplied to the second liquid chamber 15 of the cylinder 11 so that the rod of the cylinder 11 12 is to exit.

The operation amount detector 21 detects the operation amount of the control lever 18, and a well-known stroke sensor can be applied. The limit stroke detector 23 detects that the rod 12 has advanced to the limit stroke by contacting the protrusion 12a provided on the rod 12 of the cylinder 11, and a limit switch or a stroke sensor can be applied. It is.

Next, the basic operation of the hydraulic device will be described. First, as shown in FIG. 2, when the control lever 18 is neutral, the control valve 9 is at the position B,
The first port 10a and the fourth port 10d are connected, and the second port 10b and the third port 10c are blocked. In this state, a predetermined amount of hydraulic oil is discharged from the hydraulic pump 7, and the hydraulic oil passes through the pipe 19a, the first port 10a, the fourth port 10d, and the pipe 19d, and flows through the oil reservoir tank 8 Bypassed to Therefore, the hydraulic oil in the cylinder 11 does not flow, and the rod 12
That position is maintained.

Then, the driver operates the boom 3A and the arm 3B.
Alternatively, in order to operate the bucket 4, when each control lever 18 is tilted in the X direction by a desired operation amount, each control valve 9 moves to the position A in conjunction with the control lever 18, and the first port 10a is connected to the first port 10a. The second port 10b is connected, and the third port 10c and the fourth port 10d are connected. Then, when the control circuit 24 operates the electric motor 6 at a rotation speed corresponding to the operation amount of the control lever 18, the hydraulic pump 7 sucks the hydraulic oil in the oil reservoir tank 8 and discharges it from the discharge port.

Accordingly, the hydraulic oil discharged from the hydraulic pump 7 is supplied to the pipe 19a, the check valve 25, the first port 10a, the second port 10b of the control valve 9, and the pipe 1a.
9b, it flows into the first liquid chamber 14 of the cylinder 11. As a result, the rod 12 of the cylinder 11 advances rightward in the figure when the piston 13 is pressed to the right side in the figure and moved by the hydraulic pressure of the hydraulic oil accumulated in the first liquid chamber 14.

The movement of the piston 13 causes the hydraulic oil in the second liquid chamber 15 of the cylinder 11 to flow through the pipe 19c,
Third port 10c, fourth port 10 of control valve 9
d, and is discharged into the oil sump tank 8 through the pipe 19d.

When the rod 12 of the cylinder 11 has reached the limit stroke during the advance, the limit stroke detecting means 23 detects the limit stroke, and the control circuit 24 controls the electric motor 6 to reduce the rotation speed. As a result, the discharge amount of hydraulic oil from the hydraulic pump 7 decreases.

On the other hand, when the user tilts the control lever 18 in the Y direction by a desired operation amount, the control valve 9 moves to the C position in conjunction with the control lever 18, and the first port 10a and the third port 10c are moved. While being connected, the second port 10b and the fourth port 10d are connected. Then, in the same manner as described above, the control circuit 24 operates the electric motor 6 at a rotation speed corresponding to the operation amount of the control lever 18 so that the hydraulic pump 7 sucks the hydraulic oil in the oil reservoir tank 8 and discharges the oil. Discharge from.

As a result, the hydraulic oil passes through the pipe 19a, the check valve 25, the first port 10a and the third port 10c of the control valve 9, and the pipe 19c, and passes through the cylinder 11
Flows into the second liquid chamber 15. Thereby, the cylinder 1
The first rod 12 retreats leftward in the drawing as the piston 13 is moved by being pressed by the hydraulic pressure of the hydraulic oil accumulated in the second liquid chamber 15.

The hydraulic oil accumulated in the first liquid chamber 14 of the cylinder 11 due to the movement of the piston 13
The oil is discharged into the oil reservoir 8 through the pipe 19b, the second port 10b and the fourth port 10d of the control valve 9, and the pipe 19d.

If the oil pressure in the hydraulic circuit is about to exceed the set pressure while the hydraulic oil is being supplied to the cylinder 11, the relief valve 20 provided on the branch pipe side of the pipe 19a opens, and the relief valve 20 is opened. Hydraulic oil is stored in the oil reservoir 8 via
Is discharged. As a result, it is possible to prevent the inside of the hydraulic circuit from becoming equal to or higher than the set pressure.

The cylinder 1 to which the bucket 4 and the like are connected
When the control valve 9 for one is attached to the rod 12 of the cylinder 11 while the control valve 9 is in the position B, the second port 10b and the third port 10c of the control valve 9
Are blocked, these ports 10b,
There is a case where confinement pressure is applied to 10c. Therefore, when the position of the control valve 9 is switched in this state, the hydraulic oil flows backward from the cylinder 11 to the hydraulic pump 7 side, and the rod 12 may temporarily move in the opposite direction to the operation direction desired by the operator. In the present embodiment, since the check valve 25 is provided, the above problem can be prevented.

For example, in the state shown in FIG.
When a load is applied to the left rod 12 from the bucket 4 in the left direction in the figure, a closing pressure is generated in the first liquid chamber 14. In this state, when the control lever 18 is operated so that the control valve 9 switches from the position B to the position A, the first hydraulic fluid is discharged until the hydraulic pressure of the hydraulic oil discharged from the hydraulic pump 7 rises to the confining pressure or more. The hydraulic oil in the chamber 14 flows backward to the hydraulic pump 7 side. Therefore, the worker
Although the user wants to move the rod 12 to the right in the drawing, the rod 12 is temporarily moved to the left immediately after switching. However, in the present embodiment, the inconvenience can be prevented by the check valve 25.

Further, in the conventional control circuit, the amount of hydraulic oil discharged by the hydraulic pump 7 is proportional to the number of rotations of the electric motor 6 regardless of the amount of operation of the control lever 18. The numbers are as shown in FIG.
It only relates to the load on the electric motor 6, that is, the discharge pressure of the hydraulic pump 7. Therefore, when the discharge amount of the hydraulic pump is set in accordance with the heavy load, FIG.
As shown in (A), when the load applied to the cylinder 11 is small, the discharge amount of the hydraulic oil from the hydraulic pump 7 is large. Therefore, in such a case, the rod 12 of the cylinder 11 has advanced rapidly. Conversely, when the discharge amount of the hydraulic pump is set according to the light load, as shown in FIG. 4B, when the load on the cylinder 11 is large, the discharge amount from the hydraulic pump is small. Therefore, in such a case, there is an inconvenience that the advance speed of the rod 12 of the cylinder 11 is too slow and the workability is poor.

On the other hand, in the hydraulic mechanism 5 of the present invention, as shown in FIG.
Therefore, the operability and workability can be improved, and as a result, the above problem can be solved.

Further, in the present invention, when the stroke of the rod 12 in the cylinder 11 reaches the limit value, as shown in FIG. 6, the number of revolutions of the electric motor 6 is reduced to reduce the discharge amount from the hydraulic pump 7. I can do it. Therefore, the number of rotations of the electric motor 6 is reduced,
The power consumption can be reduced, and the heat generation of the hydraulic oil can be reduced by the reduced discharge amount, so that the temperature rise of the hydraulic oil can be prevented.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the cylinder 1
Although one rod 12 is disposed so as to be able to detect that it has advanced to the limit stroke, conversely, it may be disposed so that it can detect that it has retracted to the limit stroke, or it is possible to detect both. You may.

Further, in the above embodiment, the control device of the hydraulic equipment has been described as applied to the hydraulic excavator 1. However, various hydraulic mechanisms, small transporters, and the like applied to construction machines and agricultural machines have been described.
It can be applied to lifts, medical equipment such as medical beds and chairs, lifting and lowering mechanisms for boat screws, attitude control mechanisms, tools, opening and closing mechanisms for vehicle doors and pallets, and in particular,
When there is no external hydraulic pressure source, hydraulic pressure can be easily obtained by taking in power from a battery or the like, so that the present invention can be suitably applied.

[0038]

As is apparent from the above description, in the control apparatus for hydraulic equipment according to the present invention, the number of rotations of the electric motor is controlled via the operation amount detecting means in accordance with the operation amount of the control lever, and the hydraulic pump is controlled. By adjusting the discharge amount of hydraulic oil from the cylinder, it is possible to adjust the advance and retreat speed of the cylinder rod. It can be performed. In this way, the operability is improved,
Workability can be improved.

Further, through the limit stroke detecting means,
When the rod of the cylinder reaches the limit stroke, by controlling the number of revolutions of the electric motor, it is possible to keep supplying hydraulic oil and prevent unnecessary power consumption, thereby saving energy and reducing costs. . Further, it is possible to prevent the temperature of the hydraulic oil from rising due to the circulating supply of the hydraulic oil. As a result, it is possible to prevent problems such as leakage and deterioration in lubricity due to high oil temperature.

[Brief description of the drawings]

FIG. 1 is a side view showing a hydraulic excavator to which a control device for hydraulic equipment of the present invention is applied.

FIG. 2 is a hydraulic circuit diagram of a control device for a hydraulic device according to the present invention.

FIG. 3 is a graph showing a relationship between a discharge amount and a discharge pressure of a hydraulic pump in a conventional hydraulic device.

4A and 4B show a relationship between a discharge amount of a hydraulic pump and a load actually applied in a conventional hydraulic device, wherein FIG. 4A is a graph when a heavy load is set, and FIG. 4B is a graph when a light load is set. It is.

FIG. 5 is a graph showing a relationship between a discharge amount and a discharge pressure of a hydraulic pump in the hydraulic device of the present invention.

FIG. 6 is a graph showing a relationship between a discharge amount of a hydraulic pump and a stroke of a rod in the hydraulic device of the present invention.

[Explanation of symbols]

5 ... hydraulic mechanism, 6 ... electric motor, 7 ... hydraulic pump, 8 ...
Oil reservoir tank, 9 ... control valve, 11 ... cylinder, 1
2 ... Rod, 14 ... First liquid chamber, 15 ... Second liquid, 17 ... Control lever, 18 ... Control lever, 19 ...
Piping, 21: manipulated variable detector, 23: limit stroke detector, 24: control circuit.

Claims (2)

[Claims] An electric motor, a fixed displacement hydraulic pump connected to the electric motor, a cylinder connected to the hydraulic pump, and a control member for operating the hydraulic pump via the electric motor. In the control device for a hydraulic device, an operation amount detection unit that detects an operation amount of the control member is provided, and a rotation speed of the electric motor is controlled according to a detection value of the operation amount detection unit to operate the hydraulic pump. A control device for a hydraulic device, wherein an oil discharge amount is adjusted. 2. An electric motor, comprising: a fixed displacement hydraulic pump connected to the electric motor; a cylinder connected to the hydraulic pump; and a control member for operating the hydraulic pump via the electric motor. In the control device for a hydraulic device, a limit stroke detecting means is provided on a rod of the cylinder, and when the rod reaches a limit stroke, a rotation speed of the electric motor is controlled to adjust a discharge amount from the hydraulic pump. A control device for a hydraulic device, characterized in that: