JPS59233030A - Cylinder regeneration circuit for oil-pressure shovel - Google Patents

Abstract

PURPOSE:To increase the speed of a cylinder by a method in which a regenerative poppet is provided in the gratity-lowering side passage of the cylinder, and pressure oil on the returning side of the cylinder is always connected to the cylinder supply side passage and also to a tank when the pressure on the supply side is more than a fixed pressure. CONSTITUTION:A regenerative poppet 6a is provided in the return side passage 6c of a spool valve 6 for arm when the arm cylinder 8 of an oil-pressure shovel goes down under gravity. By the regenerative poppet 6a, pressure oil on the return side of the cylinder is always allowed to flow to the cylinder supply side passage through an orifice (h). When the pressure of the cylinder supply side passage 6d exceeds a given pressure, the regenerative poppet 6a is switched by the pressure on the supply side of the cylinder, and the pressure oil is flowed through the orifice 6j of the passage 6i to a tank. The speed when the cylinder goes down under gravity can thus be increased.

Description

Detailed Description of the Invention The present invention relates to a cylinder return flow regeneration circuit for a hydraulic excavator, and its purpose is to regenerate the entire cylinder return flow flow to the cylinder supply side when the cylinder drops under its own weight due to an external force. 2) When the pressure on the cylinder supply side increases to a certain pressure due to excavation resistance, etc., the cylinder return flow rate is returned to the tank side.
The objective is to make effective use of cylinder driving force.

Figure 1 is a circuit diagram of a conventional hydraulic excavator, where 1 is a pump,
2 is a control valve, and the valve 2 is a relief valve 3. It is composed of a traveling spool valve 4, a turning spool valve 5, and an arm spool valve 6. 7 is a hydraulic oil tank, 8 is an arm cylinder, 9 is an arm cylinder 8
10 is a pipe connected to the bottom side of the arm cylinder 8. Reference numeral 11 denotes a flow rate-limiting check valve provided in the pipe line 9 connected to the rond side of the arm cylinder.

In this way, by restricting the pipe line 9 on the cylinder return side using the flow rate limiting check valve 11, the cylinder speed is regulated to match the flow rate of the pump entering the cylinder supply side.

This conventional method does not generate negative pressure on the cylinder supply side. However, since the cylinder speed cannot be increased due to the presence of the throttle, work efficiency inevitably deteriorates.

In the case of FIG. 2, since a flow rate limiting check valve as shown in FIG. 1 is not provided, an arm spool valve 6', which will be described next, is used. That is, the circuit is such that the flow rate on the cylinder return side is regenerated to the cylinder supply side by switching the regeneration poppet 12, thereby increasing the cylinder speed. However, with this structure, the regeneration poppet 12 does not move to the regeneration side at the beginning of switching the spool valve. Therefore, after a certain amount of time has elapsed, the regeneration poppet 12 moves to the regeneration side and the cylinder speed increases. This means that the cylinder speed fluctuates during operation, and smooth operation cannot be expected.

FIG. 3 shows a circuit according to the invention. The difference between FIG. 3 and FIG. 1 is that an arm spool valve 6'' is installed in place of the flow rate limiting check valve J1.

FIG. 4 shows the internal circuit of the arm spool valve when the spool valve 6'' is switched to the "A position". 6a
is a regenerated poppet, 6b is a spring that tries to maintain the regenerated poppet 1-6a at the "A position" at all times, and 6c is a pipe connected to the rod side of the arm cylinder 8 when the arm spool valve 6" is set to the "A position". This is a passageway that connects to road 9. 6d is a passage connected to the conduit 10 connected to the bottom side of the arm cylinder 8 when the arm spool valve 6'' is set to the "A position", and 6e is the regenerated poppet 6a by the pressure generated in the passage 6d.
a passageway provided so that the switch can be switched to the "mouth position", 6
f is an orifice provided in the passage 6e, and 6g is a passage connecting the passage 6c and the passage 6d when the regenerating poppet 6a is in the "A" position. 6h is an orifice provided in passage 6d.

61 is a passage that connects the passage 6C and the tank passage when the regeneration poppet 6a is in the "mouth position"; 6J is the passage 61;
The orifice provided in 6 is the spring 6 of the regenerated poppet 6a.
Passage connecting the b-side chamber and tank passage, 6Q is passage 6
This is a damping orifice provided at k.

Next, the operation will be explained.

3-A) When the packet (not shown) is off the ground and switched to the arm spool 6 "PrA position", the arm cylinder 8 receives a force in the direction of extension due to the weight of the packet arm, resulting in a drop due to its own weight. In this case, arm cylinder 8
The conduit 9 connected to is the return side, and the conduit 10 is the supply side.

In this state, for example, when the pressure in the conduit 10 is low, that is, when the dead weight of the arm cylinder 8 is falling quickly, the regeneration poppet 6a is held in the "A position" by the force of the spring 6b, so the return side pipe Since the path 9 communicates with the conduit 10 via the path 6g+6d, the rod side return flow rate of the arm cylinder 8 is regenerated to the bottom side of the arm cylinder 8. In other words, the flow rate supplied to the bottom side of the arm cylinder 8 is the sum of the pump discharge amount and the return flow rate on the rod side of the arm cylinder 8.

In order to prevent the arm cylinder 8 from moving faster than the total flow rate, an orifice 6h is provided in the passage 6g to regulate the return flow rate on the rod side of the arm cylinder 8.
has been established. It is desirable that the diameter of the orifice 4-6h is such that a certain amount of pressure can be generated on the bottom side of the arm cylinder 8.

In this case, a similar pressure is generated in the passage 6e and tries to move the regenerated poppet 6a to the "mouth position", but the spring 6b
Attempts to maintain the ``A'' position using the force of

Therefore, if the setting force of the spring 6b is set to an appropriate value,
The regenerated poppet 6a can be placed at the optimal position "A" or "Mouth". In addition, in order to regulate the return flow rate on the rod side of the arm cylinder 8 even when it is suddenly switched to the "A" or "Open" position, an orifice 6j is provided in the passage 61 to regulate the flow rate, and the arm cylinder 8 There is no speed change.

B) When the arm spool 6'' is switched to the "A position" in the digging state, a considerable amount of pressure is required on the bottom side of the arm cylinder 8 in the normal digging state. Therefore, the regenerated poppet 6a overcomes the spring 6b and moves to the "r" position, and the arm cylinder 8
The return flow rate on the rod side flows through the conduit 9 and the passages 6c and 6i to the tank passage, similar to the conventional circuit.

As described above, when the arm spool 6'' is switched to the A position to extend the arm cylinder 8, the packet is f1!
! ”, the regeneration spool 6a is moved to the “A” position until the pressure on the cylinder side of the arm cylinder 8 reaches the coercive pressure.
Therefore, the return flow rate on the rod side of the arm cylinder 8 is regenerated to the bottom side of the arm cylinder 8, allowing quick operation.

Also, during excavation, the regenerated poppet 1-68 is in the "mouth position", and the circuit is the same as the conventional one.

In the above description, the spool valve for an arm was explained, but the same effect can be obtained even if it is used for a spool valve for a bucket.

[Brief explanation of drawings]

Figure 1 shows an example of a cylinder regeneration circuit for a conventional hydraulic excavator. Figure 2 is also the second example. FIG. 3 shows a cylinder regeneration circuit for a hydraulic excavator according to the present invention. Figure 4 is a detailed diagram of the internal circuit when the arm spool valve is switched to the FA position. Refer to the diagram; 1 pump 2 controller 1 to roll valve 3 relief valve 4 travel spool valve 5 swing spool valve 6, 6', 6' arm spool valve 7 hydraulic oil tank 8 arm cylinder 9 (arm cylinder's Rondo side) Conduit 10 (Bottom side of arm cylinder)
Pipe line 11 Flow rate limiting check valve 6a Regeneration poppet 6b Spring 6c (pressure oil) passages 6d, 6e, 6g, 6i, 6k Oil passages 6j, 6h
Orifice 6F, 6Q, (for dumping) orifice and above Applicant: Isamu Ohashi, patent attorney, Sumitomo Heavy Industries, Ltd.

Claims (1)

[Claims] When the arm cylinder (8) of the hydraulic excavator receives a force in the direction of extension due to the weight of the packet or arm and falls under its own weight, the arm spool valve has a circuit that regenerates the return flow rate of the arm cylinder to the supply side. The spool valve has a regeneration poppet (6a) whose regeneration circuit is constantly maintained by a spring (6b), and the regeneration poppet (6a)
so that the cylinder return flow rate always flows into the cylinder supply side passage through the orifice (6h), and when the cylinder supply pressure exceeds a predetermined pressure, the pressure causes the regeneration poppet (6a
) is switched to flow into a tank passage through an orifice (6j).