JPH0245521Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a valve inserted into a hydraulic cylinder circuit to control the operating speed of the hydraulic cylinder. Conventional technology Normally, an oil passage is formed to supply pressure oil from a hydraulic pump to a hydraulic cylinder via a switching valve, and oil is sent alternately to the head side oil chamber and rod side oil chamber of the hydraulic cylinder under the same conditions. It's like that. However, the pressure receiving area of this hydraulic cylinder is slightly different between the head side and the rod side, and the rod side is smaller by the cross-sectional area of the piston rod. Therefore, when the hydraulic cylinder is operated, when pressurized oil is sent to the head side oil chamber to cause it to expand, the operating force is slightly larger than when pressure oil is sent to the opposite rod side to cause it to contract, but the operating speed is slower. In a hydraulic excavator that uses such a hydraulic cylinder, for example, if the arm cylinder is used to operate the arm, it is arranged so that excavation work can be performed when pressure oil is supplied to the head side oil chamber. It's summery. This is ideal because the side with greater operating force is the digging side. Problems to be solved by the invention The above-mentioned operation of the arm cylinder is such that the front part of its operating range is not used for digging, but the actual digging is done after the bucket reaches the digging point. Previously, simply lowering the arm did not require much actuation force, and a fast actuation speed was required to reach the digging point in a short time.
In this way, the same hydraulic cylinder was required to have a contradictory state of high operating speed and large operating force at a certain point, but conventionally it was possible to operate only at large operating force and slow speed, so it was difficult to operate under light loads. There was a huge loss of time in the operation of the machine, which reduced work efficiency. The object of the present invention is to solve the above problems and provide a hydraulic valve whose operating speed can be increased or decreased in response to the load. Means for Solving the Problems The means of the present invention taken to solve the above problems are: (a) A valve is provided in the circuit between the hydraulic cylinder and the switching valve for its operation. (b) An annular groove that communicates with the cylinder, the head side oil chamber of the hydraulic cylinder, and the switching valve at the same time, and an annular groove that communicates with the rod side oil chamber of the hydraulic cylinder;
The valve body must have an oil chamber that communicates with the switching valve. C. A land part that is inserted into the cylinder of the valve body and opens and closes between the oil chamber and the annular groove leading to the rod side oil chamber, and when the land part is closed, there is a slight amount of oil between the annular groove and the oil chamber. It has an oil passage with a restriction that allows oil flow, an oil passage that opens and closes between the left and right annular grooves, and a poppet that is installed in the oil passage and allows oil to flow only from the rod side oil chamber to the head side oil chamber. Must be a spool. (d) A small diameter spring that is inserted between the valve body and the spool and acts when the oil pressure in the head side oil chamber that acts on the spool is low, and a large diameter spring that acts when the oil pressure is high. It is. Function When pressure oil is supplied to the head side oil chamber of the hydraulic cylinder and the hydraulic cylinder is extended, and the load is small, the spool acts on a small diameter spring and switches, diverting the return oil from the rod side oil chamber. It operates at a high speed because it merges into the head side oil chamber. When the load increases, the spool acts on the large diameter spring, the spool is switched, and the return oil from the rod side oil chamber returns to the tank, so the operating speed slows down, but the operating force increases. In this way, the operating speed of the hydraulic cylinder when the load is light is increased, so that work efficiency is improved. Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings. 1 is a valve body, which has a cylinder 2 inside, and has an annular groove 3 in the middle part and another annular groove 4 on the right side thereof, and the annular groove 3 in the middle part has an oil port 5. The annular groove 4 on the right side communicates with the head side oil chamber 11 of the hydraulic cylinder 7 through an oil port 9 and an oil path 10. The annular groove 4 also communicates with a switching valve 14 via an oil port 12 and an oil passage 13. 15 is the oil chamber on the left side of the main body, oil port 16,
It communicates with the switching valve 14 via an oil passage 17 . A spool 18 is used to bypass the return oil from the rod side oil chamber 8 to the head side oil chamber 11 when the hydraulic cylinder 7 is extended, or to return it directly to the tank 35. It is slidably inserted into the cylinder 2 of 1. The spool 1
8 has a small diameter part 20, a land part 21, and an annular groove 22 formed from the left side, and an oil passage 23 is bored from the outer peripheral surface of the small diameter part 20 to the annular groove 22.
A diaphragm 24 is provided in the middle part of 3. Further, the spool 18 has an oil chamber 25 on the right side, and the oil chamber 25 has an oil chamber 25 on the right side.
5 is an oil port 26 which is always in communication with the annular groove 4 . 27
is the oil passage, and one is the spool 1 near the annular groove 22.
8, and the other side communicates with the oil chamber 25. A poppet 28 is attached to the opening to the oil chamber 25 and is pushed by a spring 19.
This allows oil to flow only in the direction indicated by 5. 29 and 30 are spring receivers inserted on the left and right sides of the oil chamber 15 , and a large diameter spring 31 is inserted between the two, but the right spring receiver 30 is formed in a ring shape, and its inner diameter is the same as that of the spool. It is smaller than the outer diameter of the land portion 21 of 18, so that the spring receiver 30 can be pushed when the spool 18 moves to the left.
Further, a small diameter spring 32 is interposed between the spring receiver 29 and the side end of the small diameter portion 20 of the spool 18.
Note that 33 is an oil hole, 34 is a hydraulic pump, and 35 is a tank. When contracting the hydraulic cylinder 7, that is, when sending pressure oil to the rod-side oil chamber 8 of the hydraulic cylinder 7, the switching valve 14 is switched to the right side. hydraulic pump 3
Pressure oil from 4 enters the oil chamber 15 through the switching valve 14 , the oil passage 17, and the oil port 16 . Since there is no pressure oil in the oil chamber 25 on the right side of the spool 18, the spring 32
Since the oil chamber 15 and the annular groove 3 are pressed to the right limit, and there is a wide gap between the oil chamber 15 and the annular groove 3, the pressure oil is
5, enters the rod-side oil chamber 8 of the hydraulic cylinder 7 via the annular groove 3 , oil port 5, and oil passage 6. On the other hand, the head side oil chamber 11 includes an oil passage 10, an oil port 9, an annular groove 4 , and an oil port 1.
2. Since it communicates with the tank 35 via the oil passage 13 and the switching valve 14 , the hydraulic cylinder 7 contracts. Next, when extending the hydraulic cylinder 7,
Switch the switching valve 14 to the left side, contrary to the above. Pressure oil from the hydraulic pump 34 flows through the oil passage 13, the oil port 12,
It enters the head side oil chamber 11 of the hydraulic cylinder 7 via the annular groove 4 , oil port 9, and oil passage 10. On the other hand, the oil in the rod side oil chamber 8 flows through the oil passage 6, the oil port 5, the annular groove 3 , and the oil chamber 1.
5, the oil flows out into the tank 35 via the oil port 16, oil path 17, and switching valve 14 , and the hydraulic cylinder 7 is extended. However, in this case, the pressure oil from the annular groove 4 communicates with the oil chamber 25 through the oil port 26, and the oil chamber 25 communicates with the right end of the spool 18 through the oil hole 33, so the spool 18 moves to the left against the spring 32 at the left end by an amount commensurate with the action of the pump discharge pressure acting on the right end surface. The oil passage 27 opens into the annular groove 3 , and the left corner A of the land portion 21 opens into the cylinder 2.
Approaching the corner C of the left side B of , the circuit leading from the annular groove 3 to the oil chamber 15 is constricted, and another oil passage 23 leading from the annular groove 3 to the oil chamber 15 has a throttle 24. As a result, the oil pressure of the return oil in the annular groove 22 increases, pushing the poppet 28 from the oil passage 27 and flowing into the oil chamber 25.
flows to Of course, the spring 32 that pushes the spool 18 to the right is a small diameter spring and is set to a very small force, so it is activated when the oil pressure in the oil chamber 25 that moves the spool 18 becomes slightly high, and the rod is moved. The return oil from the side oil chamber 8 joins the circuit leading to the head side oil chamber, increasing the operating speed of the hydraulic cylinder 7 under low pressure.
If the load on the hydraulic cylinder 7 further increases slightly and the spool 18 moves to the left, the land portion 21 will move toward the cylinder 2.
, and blocks the passage between the annular groove 3 and the oil chamber 15 . Although some of the oil leaks through the oil passage 23 and the throttle 24, most of the return oil flows through the oil passage 27 and the poppet 28 into the oil chamber 25 that communicates with the head side oil chamber 11, as described above, and then flows into the hydraulic cylinder. 7 elongates at a fast rate as before. The above is a case of a light load, for example, when the arm is lowered by a hydraulic excavator until the excavation bucket reaches the excavation point on the ground, the pump discharge pressure is operated at a low state, and the spool 18 is operated at a low setting force. It was acting only on the small diameter spring 32. In this state, the return oil in the rod-side oil chamber 8 of the hydraulic cylinder 7 merges with the working pressure oil in the head-side oil chamber 11, and the operating speed of the hydraulic cylinder 7 increases. When the excavation bucket reaches the excavation point and enters the excavation state from this state, the load increases and the pump discharge pressure increases, so the spool 18 is pushed to the left and the side end of the land portion 21 touches the spring receiver 30. It acts on the large diameter spring 31 through it and pushes the spring 31 to the left. When the land portion 21 leaves the B portion of the cylinder 2, the spring receiver 30 moves to the left together with the land portion 21. Return oil passes through the gap between the inner peripheral surface of the oil chamber 15 and the outer peripheral surface of the spring receiver 30 and returns to the oil chamber 15.
The passage between the annular groove 3 and the oil chamber 15 is opened. All the return oil from the rod side oil chamber 8 returns to the tank 35 through the oil chamber 15 , oil port 16, oil passage 17, etc. The hydraulic cylinder 7 and the switching valve 14 are in a state similar to a normal hydraulic cylinder operating circuit in which they are connected in a straight line, and the return oil from the rod side oil chamber 8 returns to the tank 35 without being throttled on the way, so the hydraulic pressure The cylinder 7 operates in its normal state, ie with a greater actuation force and a lower speed than described above. In this way, the valve of the present invention changes the operating speed of the hydraulic cylinder 7 to the circuit between the hydraulic cylinder 7 and its operation switching valve 14 so that the operating speed of the hydraulic cylinder 7 is fast in the case of light loads and slow in the case of heavy loads. Therefore, by operating the switching valve 14 , the hydraulic cylinder 7
When sending pressure oil to the head-side oil chamber 11 of the spool 18, the spool 18 acts only on the small-diameter spring 32 while the load is small in the initial stage and the working oil pressure is low, and the land portion 21 of the spool 18 acts on the return oil path. Close the oil passage 2
7. Since the hydraulic cylinder 7 is connected to the circuit of the head side oil chamber 11 through the poppet 28, the operating speed of the hydraulic cylinder 7 is increased, and the working speed under light loads can be increased.
If the load on the hydraulic cylinder 7 increases, the spool 1
8 moves to the left and acts on the large diameter spring 31, and the land portion 21 opens the return oil passage between the annular groove 3 and the oil chamber 15 , so the return oil from the rod side oil chamber 8 is throttled. I returned to tank 35 without any problem and replaced hydraulic cylinder 7.
operates at normal speed. Effects of the invention In the hydraulic cylinder circuit equipped with the speed increasing valve according to this invention, an annular groove 4 is provided inside the valve body 1 and simultaneously communicates with the cylinder 2, the head side oil chamber 11 of the hydraulic cylinder 7, and the switching valve 14 . Since the annular groove 3 communicating with the rod side oil chamber 8 and the oil chamber 15 communicating with the switching valve 14 are formed, the hydraulic cylinder 7 can be operated immediately by switching the switching valve 14 . In the above case, even if an external force is applied to the hydraulic cylinder 7 in the direction of extension or contraction , the oil passage 6 Since the passage leading from the oil passage 17 to the oil passage 17 is always open, the hydraulic cylinder 7 can be operated immediately without any trouble. For example, even if the engine is stopped with the hydraulic cylinder 7 contracted and the arm lifted upward, if the oil passage 17 is made to flow through the tank 35 by operating the switching valve 14, the oil passage 17 will be Since the hydraulic cylinder 7 is open to the rod-side oil chamber 8 of the cylinder 7, the hydraulic cylinder 7 is contracted by the arm's own weight, and the arm can be lowered to a safe state. If the load is light when the hydraulic cylinder 7 is extended, the return oil from the rod-side oil chamber 8 joins the pressure oil flowing into the head-side oil chamber 11, increasing the operating speed and causing rapid expansion. When the load increases, the return oil from the rod-side oil chamber 8 returns to the tank 35, so the pressure in the rod-side oil chamber 8 decreases and the effective pressure against the hydraulic cylinder 7 increases, allowing it to operate with the normal large force. . Therefore, when the speed increasing valve according to this invention is used in a hydraulic cylinder circuit, when the switching valve 14 is operated to switch, the hydraulic cylinder 7 is immediately and without any trouble.
In addition to increasing the operating speed to the excavation point, the work cycle time can be shortened and work efficiency can be improved.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the present invention, Fig. 2, Fig. 3,
4 and 5 are partial vertical sectional views showing the operating state of the present invention. DESCRIPTION OF SYMBOLS 1... Valve body, 2... Cylinder, 3 ... Annular groove, 4 ... Annular groove, 7... Hydraulic cylinder, 8...
...Rod side oil chamber, 11...Head side oil chamber, 14 ...
...Switching valve, 15 ...Oil chamber, 18...Spool, 2
1... Land portion, 23... Oil path, 24... Throttle,
27...Oil passage, 28...Poppet, 31...Spring, 32...Spring, 34...Hydraulic pump.

Claims (1)

[Scope of utility model registration request] A valve is interposed in the circuit between the hydraulic cylinder and its operation switching valve, and when the hydraulic cylinder is under a light load, the spool in the valve is moved to increase the extension speed of the hydraulic cylinder and cause the extension operation. In this hydraulic cylinder control device, an annular groove 4 communicating with the cylinder 2, the head side oil chamber 11 of the hydraulic cylinder 7 and the switching valve 14 at the same time, and an annular groove 3 communicating with the rod side oil chamber 8 are provided inside the valve body 1. and,
An oil chamber 15 communicating with the switching valve 14 is formed, and a spool 18 is slidably provided in the cylinder 2, and the spool 18 has an annular groove 22, a land portion 21, an annular groove 3 and an oil chamber 15. an oil passage 23 provided with a throttle 24 that allows a slight flow of oil between the two; an oil passage 27 that opens and closes between the left and right annular grooves 3 and 4 ; A poppet 28 is provided that allows oil to flow only to the poppet 2.
An oil hole 33 communicating between the downstream side of the valve body 1 and the right end side of the spool 18 is bored, and a light load spring 32 is provided in the oil chamber 15 between the left end inside the valve body 1 and the left end of the spool 18. A spring 31 for heavy loads is provided between the left end of the inside of the valve body 1 and the spring receiver 30 of the stepped portion of the right end of the oil chamber 15 , and when the hydraulic cylinder 7 is extended under light loads, the spool 18 is moved by the spring force of the spring 32. The spool 18 moves against the springs 31 and 3 to enable the annular groove 3 to communicate with the annular groove 4 , and when the hydraulic cylinder 7 is extended under heavy load, the spool 18 moves against the springs 31 and 3.
The annular groove 3 and the oil chamber 15 move against the spring force of 2.
A speed increasing valve characterized in that the valve is configured to be able to communicate with each other through an annular groove 22 of a spool 18.