JPH10212728A - Hydraulic circuit for construction machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic circuit for a hydraulic drop hammer capable of increasing the pressure in a hydraulic cylinder at the start of moving even if the hydraulic device is miniaturized. SOLUTION: A hydraulic pressure supply circuit 11 from a variable delivery pump 6 is connected to the chamber 5a on the rod side of a hydraulic cylinder 5, and a stroke sensor 8 for detecting the position and speed of a piston 2 inside the hydraulic cylinder 5, and a pressure sensor 9 for detecting the load inside the hydraulic cylinder 5 are arranged. A control mechanism 10 for controlling the pressure and flow rate of the variable delivery pump 6 on the basis of the signals both from the stroke sensor 8 and from the pressure sensor 9 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for a construction machine such as a hydraulic drop hammer or a hydraulic vibro hammer.

[0002]

2. Description of the Related Art In a hydraulic drop hammer, for example, a weight is suspended from a rod end of a piston in a hydraulic cylinder, a circuit from a hydraulic pump is connected to a rod side chamber of the hydraulic cylinder, and a switching valve is provided from the hydraulic pump through a switching valve. By supplying pressure oil to the rod side chamber, the piston is moved to raise the weight, and when the pile is hit, the switching valve is switched so that the pressure oil supplied to the rod side chamber is discharged, and the weight is dropped by its own weight. I have.

Conventionally, a constant displacement pump has been used as a hydraulic pump for driving the hydraulic cylinder, and a constant pressure and a constant flow rate of pressurized oil have been supplied. Since the most force is required at the beginning of the movement of the piston, the selection of the hydraulic pump was determined by the maximum pressure and the maximum flow rate.

[0004]

However, most of the steps other than the start of the movement of the piston require the flow rate but the pressure does not have to be maximum, so that the power always supplied in the actual movement is used up. No, the hydraulic system was upsized.

Accordingly, an object of the present invention is to provide a hydraulic circuit of a hydraulic drop hammer that can increase the pressure at which the hydraulic cylinder starts to move even if the hydraulic device is downsized.

[0006]

In order to achieve the above-mentioned object, the present invention relates to a hydraulic cylinder, comprising connecting a hydraulic oil supply circuit from a hydraulic pump to a rod side chamber of a hydraulic cylinder, and switching between supply and discharge of hydraulic oil. In a hydraulic circuit of a construction machine for reciprocating a piston in a cylinder, a stroke sensor for detecting a position and a speed of the piston and a pressure sensor for detecting a load in the hydraulic cylinder while the hydraulic pump is a variable displacement pump. And a control mechanism for controlling the pressure and the flow rate of the variable displacement pump based on signals from the stroke sensor and the pressure sensor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a hydraulic drop hammer will be described below with reference to the drawings.

The hydraulic circuit 1 of the hydraulic drop hammer includes a hydraulic cylinder 5 having a weight 4 suspended at the tip of a rod 3 of a piston 2, a variable displacement hydraulic pump 6 for driving the hydraulic cylinder 5, and a variable displacement hydraulic pump 6 Valve 7 for switching between supply and discharge of the pressure oil supplied from the hydraulic cylinder 5 to the hydraulic cylinder 5, and a stroke sensor 8 for detecting the position and speed of the piston 2
And a pressure sensor 9 for detecting a load in the hydraulic cylinder 5
And a control mechanism 10 for controlling the pressure and flow rate of the variable displacement hydraulic pump 6 based on signals from the stroke sensor 8 and the pressure sensor 9.

A pressure oil supply circuit 11 extending from the variable displacement hydraulic pump 6 is provided with an accumulator 12 and is connected to a switching valve 7. The switching valve 7 has a rod-side chamber 5 of a hydraulic cylinder 5.
a, a rod-side circuit 13 connected to the hydraulic circuit 5, a head-side circuit 14 connected to the head-side chamber 5 b of the hydraulic cylinder 5, and a discharge circuit 16 to the oil tank 15.
Is provided with an accumulator 17.

The stroke sensor 8 is provided at the end of the rod side chamber 5a of the hydraulic cylinder 5, and has a control mechanism 10
8 and the pressure sensor 9 is connected to the head side circuit 1
The control mechanism 10 and the variable displacement hydraulic pump 6 are connected to each other by an electric wire 20. Incidentally, 21 is a relief valve.

The operation of the hydraulic circuit 1 configured as described above will be described. When the switching valve 7 connects the pressure oil supply circuit 11 and the head-side circuit 13, the pressure oil is supplied from the variable displacement hydraulic pump 6. At the stage where supply to the hydraulic cylinder 5 is started, the piston 2 is lowered to the lowest point of the hydraulic cylinder 5 by the weight of the weight 4.

The stroke sensor 8 detects the position of the piston 2 and sends a signal to the control mechanism 10, and the pressure sensor 9 detects that the pressure of the head side circuit 14 is low and sends a signal to the control mechanism 10. , The control mechanism 10 sends a command to supply the maximum-pressure hydraulic oil to the variable displacement hydraulic pump 6.

Thus, in the first stage in which the hydraulic drop hammer makes one hit, the rod side chamber 5 of the hydraulic cylinder 5
The pressure oil of the maximum pressure is supplied to a, the piston 2 starts to move upward, and the weight 4 starts to rise.

When the piston 2 starts moving upward, the stroke sensor 8 detects the position and speed of the piston 2 and sends a signal to the control mechanism 10, and the pressure sensor 9 detects the load on the hydraulic cylinder 5 and 10 and the control mechanism 10 sends a command to the variable displacement hydraulic pump 6 to supply a pressure oil required for raising the piston 2 and a maximum flow rate of pressure oil. When the piston 2 rises to the highest position, the switching valve 7 switches to discharge the pressure oil in the rod side chamber 5a of the hydraulic cylinder 5 to the oil tank 15 via the discharge circuit 16, and the weight 4 falls freely.

In this way, the variable displacement hydraulic pump 6 is controlled so as to supply the required pressure and flow rate of hydraulic oil to the hydraulic cylinder 5 in accordance with the operating condition of the hydraulic cylinder 5, so that the power source The power can be used efficiently, the hydraulic device can be downsized, and the variable displacement hydraulic pump 6 is electrically controlled, so that the operation can be performed efficiently with no reaction delay.

In the above embodiment, the present invention is applied to a hydraulic drop hammer. However, the present invention is also applicable to a hydraulic vibratory hammer.

[0017]

As described above, in the hydraulic circuit of the construction machine according to the present invention, the pressure oil supply circuit from the variable displacement pump is connected to the rod side chamber of the hydraulic cylinder, and the position and speed of the piston in the hydraulic cylinder are controlled. Since a stroke sensor for detecting the pressure and a pressure sensor for detecting the load in the hydraulic cylinder are provided, and a control mechanism for controlling the pressure and the flow rate of the variable displacement pump based on the signals from the stroke sensor and the pressure sensor is provided. , Corresponding to the operating condition of the hydraulic cylinder,
By controlling the variable displacement hydraulic pump to supply the required pressure and flow rate of hydraulic oil to the hydraulic cylinder, the power of the power source can be used efficiently, and the hydraulic device can be downsized and Since the variable displacement hydraulic pump is controlled in a controlled manner, it is possible to work efficiently without any reaction delay.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic drop hammer showing an embodiment of the present invention.

[Explanation of symbols]

1: hydraulic circuit, 2: piston, 3: rod, 4: weight,
5 hydraulic cylinder, 5a rod side chamber, 6 hydraulic pump, 7 switching valve, 8 stroke sensor, 9 pressure sensor, 10 control mechanism, 11 hydraulic oil supply circuit

Claims (1)

[Claims] 1. A hydraulic circuit for a construction machine in which a hydraulic oil supply circuit from a hydraulic pump is connected to a rod side chamber of a hydraulic cylinder, and the supply and discharge of the hydraulic oil is switched to reciprocate a piston in the hydraulic cylinder. The hydraulic pump is a variable displacement pump, a stroke sensor for detecting the position and speed of the piston, and a pressure sensor for detecting a load in the hydraulic cylinder are provided, and signals from the stroke sensor and the pressure sensor are provided. A hydraulic circuit for a construction machine, comprising: a control mechanism for controlling a pressure and a flow rate of the variable displacement pump based on the following.