JPH0567802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to the structure of a pilot switching valve controlled by a hydraulic remote control valve in a hydraulic system for actuating an actuator of a construction machine or the like.

Prior Art A pilot switching valve controlled by a hydraulic remote control valve is connected by a pilot oil passage, and pilot pressure oil from the remote control valve acts on the pilot oil chamber of the pilot switching valve. By moving the spool to the left or right, the switch can be switched. Since remote control valves are usually intended to control pilot switching valves from a remote location, their oil passages are long, and since they only operate a spool, they do not require a large amount of oil. Because there are so many, it is difficult to secure enough space, so the diameter of the pilot oil passage piping is not made that large. Therefore, flow resistance within the piping tends to be large. Furthermore, when the pilot pressure oil from the remote control valve acts on one pilot oil chamber of the pilot switching valve, the oil in the pilot oil chamber on the opposite side is pushed out by the movement of the spool and passes through the pilot oil path and the remote control valve. Return to the tank. Since the piping of the pilot oil passage is long and small in diameter, although the spool does not operate very quickly, there is considerable oil flow resistance when the spool operates, and this is added to the above-mentioned resistance, resulting in a time lag. Particularly in cold weather, the viscosity of oil increases and the flow resistance increases, which not only tends to cause time lags due to the resistance of the long and thin pilot oil passage, but also reduces the chances of removing the air trapped in this pilot oil passage. , the unfavorable condition that a time lag occurs is compounded. One of the conventional techniques to deal with these problems is Utility Application No. 58-40700
No.), but the content is that instead of the spool shown in Figure 9, there is a vertical notch near the side end of the spool of the pilot switching valve that leads to the pilot oil chamber, as shown in Figure 10. As shown in the hydraulic circuit in Figure 11, by drilling the hydraulic circuit, it is shut off when no pilot pressure is applied, but when the spool moves due to pilot pressure, the return oil passage and the pilot The oil chambers communicate through a notch, and a portion of the oil in the pilot oil chamber passes through the notch and flows back into the oil passage. According to this method, a unidirectional flow of warm oil from the remote control valve flows into the pilot oil path, which is effective for air removal and warming up.
As shown in Fig. 2, the opening area changes depending on the spool stroke, and as a result, the amount of pilot pressure oil flowing out changes, which has the disadvantage that the fine operation of the switching valve becomes unstable.

In addition, when the switching valve starts operating, the actual volume of the pilot oil chamber on the opposite side of the pilot oil chamber to which the pilot pressure acts is smaller by the volume that the spool moves and enters. As a result, the highly viscous oil that filled the tank must be returned to the tank via small-diameter piping and a remote control valve, so the spool moves slowly due to flow resistance and special care is required for operation. be.

Furthermore, as other conventional technology,
As seen in Publication No. 54418, in order to reduce the viscous resistance of the hydraulic oil in the pilot circuit especially in cold weather and to reduce the time lag of spool displacement, a pilot pressure receiving chamber and a drain chamber in the switching valve housing are installed. Techniques for providing a flow path that directly communicates with the two are well known. In this conventional technology,
As shown in the example drawings, it is necessary to drill small holes for the flow passages at both ends of the housing, which is the largest component of the switching valve. To get the space you need,
Not only will the diameter of the pilot pressure receiving chamber become larger, increasing costs, but also the oil in the pilot oil chamber on the side where the spool moves will pass through the pilot piping and the above-mentioned flow passage, so its flow will be reduced. The resistance is great.

Problems to be Solved by the Invention In view of the above-mentioned prior art, when a remote control valve is operated, warm pressure from the remote control valve is applied to the pilot oil chamber of the pilot switching valve and the pilot piping to the oil chamber. By constantly allowing a predetermined amount of oil to flow in, the pilot circuit system is warmed up and air is removed, and the excess oil that is generated when the spool of the switching valve enters the other pilot oil chamber is eliminated. By returning the oil directly to the return oil path of the pilot switching valve, the initial movement of the spool is made easier, so there is no time lag in operation even in cold weather at the start of operation, and it also has good fine controllability. proposes a switching valve that has a simple shape, has low processing costs, and can be easily modified from a normal pilot switching valve if necessary.

Means for Solving the Problems The means of the present invention taken to solve the above problems are as follows: (a) A pilot oil passage is routed from a remote control valve to a pilot switching valve in a hydraulic system for actuator operation of construction machinery, etc. be something that

(b) Regardless of the stroke position of the spool of the switching valve, it is always connected to the drain oil passage of the switching valve, and when the spool moves in one direction, it is connected to the pilot oil chamber on that side without any flow resistance. Provide a flow path near both ends of the spool.

(c) an opening in the end face of the spool and the above-mentioned notch;
A throttle hole that communicates the pilot oil chamber and the drain oil passage of the switching valve through the notch, and that prevents flow of pilot pressure oil in excess of the capacity of the pilot pressure oil supplied to the pilot oil chamber due to its throttle effect. are provided at both ends of the spool.

It is.

Operation When the remote control valve is operated, the oil in the tank becomes pilot pressure oil and flows into the pilot oil chamber, and a predetermined amount always flows through the throttle hole and notch provided in the spool to the oil path leading to the tank of the switching valve. Therefore, the air in the pilot pressure oil system on that side is automatically vented, the pilot pressure oil is replaced, and the related oil chambers and piping are warmed up. The spool returns to the tank through the drain oil path of the switching valve via the notch in the spool without going through piping or the remote control valve, so the spool can be moved easily even at the beginning of switching, and the spool can be easily moved. Since the amount of circulating oil is stable regardless of the movement position, fine operability of the switching valve is not lost.

In addition, all of the above objectives can be achieved simply by providing a restrictor hole in the spool of a conventional switching valve, making it easy to manufacture.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings shown in FIGS. 1 to 7.

Reference numerals 1, 2, and 3 are all pilot switching valves, and oil passages 5, 6, and 7 are connected to these switching valves 1, 2, and 3 in parallel from a hydraulic pump 4, respectively. , 2, 3 are return oil passages 8,
9 and 10 respectively communicate with tank 11. 1
Reference numeral 2 designates a return oil passage during neutral state, and 13 represents an actuator, to which oil passages 14 and 15 from the pilot switching valve 1 communicate.
16 is a remote control valve, left and right valve body 1
7 and 18, and a lever device 19 for operating them, and an oil passage 21 from an auxiliary hydraulic pump 20 communicates with the valve bodies 17 and 18. A pilot oil passage 23 communicates from the left valve element 17 to the right pilot oil chamber 22 of the pilot switching valve 1, and pilot oil flows from the right valve element 18 to the left pilot oil chamber 24 of the pilot switching valve 1. Road 25 is connected. 27 is a spool, pilot oil chamber 22, 2
When pilot pressure is applied to any one of 4, it moves to the left or right and switches the main circuit. 26 indicates the right side of the spool 27 of the pilot switching valve 1, and 28 indicates the left side, and the right side 26 always communicates with the drain oil passage 46 regardless of the stroke position of the spool 27. Depth of cut 4
4, and this notch 44 is the spool 27
However, when it moves slightly to the right, the pilot oil chamber 22
There are also locations and sizes that lead to the area. Furthermore, a throttle hole 48 is provided at the right end of the spool 27, opening both ends of the notch 44 and the pilot oil chamber 22. In exactly the same way, the left side 28 has a notch 45 that is always in communication with the drain oil passage 47,
A throttle hole 49 opening both ends into the notch 45 and the pilot oil chamber 24 is provided at the left end of the spool 27.

Note that 33 is a filter, 34 is a cooler, and 35 is a relief valve.

Fig. 4 shows the inside of the pilot switching valves 1, 2, and 3, and 27 is a spool whose both ends extend into the left and right pilot oil chambers 22, 24, and the right end has a spring receiver 36. through spring 37
The left end portions are supported by springs 39 via spring receivers 38 to maintain the neutral position. Two notches 40 and 41 are symmetrically provided in the center of the spool 27 to open the return oil passages 12 at the front and rear thereof only when the spool 27 is in the neutral position. Furthermore, notches 42 and 43 are provided symmetrically on the outside, and these notches 42 and 43 are used for the oil passages 5 and 5 that are discharged from the hydraulic pump 4 when the spool 27 moves to the left or right. Pressure oil to oil line 1
The oil is supplied to the actuator 13 through the oil passages 15, 14 and the return oil passage 8.
This is for returning to the tank 11 by communicating with the tank 11. Furthermore, there are notches 44, 4 on the outside.
5 are provided symmetrically. The cuts 44, 45
always connects to the drain oil passages 6, 47, and when the spool 27 moves to the right or left, the pilot oil chambers 22, 24 and the drain oil passages 46, 47 on the side on which it moved,
It has a position and size that allows communication without resistance.
Further, throttle holes 48 and 49 are bored inside the left and right ends of the spool 27.
One end of 9 is connected to the pilot oil chamber 22, 24,
The other end opens into notches 44 and 45,
The pilot oil chambers 22, 24 are always kept in a constricted state and communicated with the drain oil passages 46, 47, and when pilot pressure oil flows into the pilot oil chambers 22, 24, a predetermined amount of the oil flows through the constricted state. hole 48,4
9 to the drain oil passages 46 and 47, but the predetermined amount at this time is set to be the maximum amount within a range that does not exceed the discharge capacity of the secondary side pressure oil of the remote control valve 16 even at the maximum. Above aperture hole 4
Aperture effects of 8 and 49 are set.

The present invention is constructed as described above, and when the actuator 13 is not actuated and the lever device 19 is in the neutral position, the oil in the auxiliary hydraulic pump 20 returns to the tank 11 from the relief valve 35 and flows through the pilot oil path 23. , 25, the pilot oil chambers 22, 24
communicates with the tank 11 via the valve bodies 17, 18, the spool 27 is held in the neutral position by the springs 37, 39, and therefore only the return oil passage 12 is open to the notches 40, 41. The oil discharged from the hydraulic pump 4 returns to the tank 11 through the return oil path 12, the cooler 34, and the filter 33.

Next, when the lever device 19 is operated, for example, to the left (in the direction of the arrow) in order to operate the actuator 13, oil from the auxiliary hydraulic pump 20 passes through the oil passage 21, the valve body 17, and the pilot oil passage 23. It flows into the pilot oil chamber 22 and pushes the spool 27 to the left against the spring 39. A notch 42 in the spool 27 allows the oil passage 5 and the oil passage 14 to communicate with each other, and at the same time, a notch 43 allows the oil passage 15 and the oil passage 8 to communicate with each other. Therefore, the pressure oil from the hydraulic pump 4 flows to the actuator 13 through the oil passage 5, the notch 42, and the oil passage 14, and the return oil flows through the oil passage 15 and the notch 4.
3. The oil returns to the tank 11 through the oil path 8, and the actuator 13 is activated. While the lever device 19 is being operated, the pressure oil of the auxiliary hydraulic pump 20 is regulated by the valve body 17 and is supplied to the pilot oil chamber 22 as secondary pressure oil, of which a predetermined amount is supplied to the throttle hole 4.
8 to the hand drain oil passage 46, but since the pressure oil is refilled into the oil chamber 22, the oil pressure maintains its value and the spool 27 resists the spring 39 on the opposite side of the spool 27. Since the spool 27 is held in that position, changes in the function of the spool 27 are not affected. Accordingly, the oil in the pilot oil chamber 22 and the pilot oil passage 23 flows out into the drain oil passage 46 through the throttle hole 48, so that the oil in the pilot oil chamber 22 and the pilot oil passage 23 gradually flows out from the auxiliary pump 20. Replaced with new oil supplied. In addition, A in FIG. 4 shown in FIGS. 5 and 6
As is clear from the enlarged view, the pilot oil chamber 22 is always in communication with the drain oil passage 46 through the throttle hole 48 regardless of the position of the spool 27. The opening area between the oil chamber 22 and the drain oil passage remains constant, so when the pilot pressure oil acts, the pressure in the pilot oil chamber 22 remains stable regardless of the movement of the spool 27. ing. When a relatively large amount of pilot pressure oil is replaced in this way without affecting the pilot function, air is removed and the time lag is eliminated. Further, the pilot oil passage 23 is a thin pipe, and the position of the operating lever 19 and the position of the switching valve 1 are located at a considerable distance, and the length thereof is long. Therefore, in cold weather, the oil temperature in the pilot oil passage 23 drops significantly and the viscosity resistance of the oil increases, which is one of the causes of time lag during remote control operation. Room 22,
Since the oil in the pilot oil passage 23 flows out into the drain oil passage 46, the oil is replaced, and warm oil from the tank 11 is supplied in place of the cold oil in the piping, so that the oil temperature and the temperature of its surrounding equipment are reduced. increases, oil viscosity resistance decreases, and time lag during operation is eliminated.

Also, by moving the spool 27 to the left against the spring 39, the notch 45 on the opposite side
allows the pilot oil chamber 24 and drain oil passage 47 to communicate with each other without resistance, so that the oil in the pilot oil chamber 24 returns to the tank 11 through the drain oil passage 47.
The spool 27 can move smoothly regardless of the presence or absence of flow resistance in the pilot oil path 25, and there is no time lag factor at all.

Next, when the operating lever 19 is operated in the opposite direction of the arrow to operate the valve body 18, the pilot pressure oil passes through the pilot oil passage 25 and is released from the spool 2.
The only difference is that 7 is moved in the opposite direction to the above, and its operation and effect are the same as described above.

Effects of the Invention This invention provides a spool that is connected to the drain oil passage near both ends of the spool of the pilot switching valve, regardless of its stroke position, and that the spool is pushed only when the spool is moved by the pilot pressure oil. a notch at a position and size such that the pilot oil chamber on the side where the pilot oil chamber is connected communicates with the drain oil passage, and a throttle hole opening both ends of the notch and the pilot oil chamber,
The maximum amount of pilot pressure oil that passes through the throttle hole is
Since the throttling effect of the throttle hole is set to be maximum within the range that does not exceed the secondary side discharge capacity of the remote control valve, when the remote control valve is operated, the pilot oil passes through the throttle hole regardless of the stroke position of the spool. A stable and large circulating flow occurs in the pipeline system, and the cold oil in the pilot piping is replaced by warm oil, and at the same time, the temperature of the piping increases, and the time lag caused by the oil flow resistance is short-lived. In addition, a large amount of circulating flow is generated in the pilot oil passage and pilot oil chamber, and the air inside is automatically discharged to the oil passage leading to the tank, eliminating the time lag caused by the presence of air. On the other hand, excess oil in the pilot oil chamber on the side where the spool is pushed and moved by the pilot pressure oil flows out to the drain oil path of the switching valve without resistance through the notch provided near the end of the spool, so as mentioned above, In addition to this, the spool time lag factor is also eliminated. In addition, in order to achieve the above effects, the present invention enables valves with complex shapes to be manufactured by simply replacing the spool of a conventional pilot switching valve with one having the shape of the present invention, or by additionally machining the spool. Since there is no need to process the main body, it is possible to obtain a pilot switching valve that is easy, inexpensive, and can exert its time lag prevention effect in a short period of time.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of an operating system equipped with the switching valve of the present invention, Figs. 2 and 3 are hydraulic circuit diagrams for explaining operating conditions, and Fig. 4 is a sectional view of the switching valve of the invention. , Figure 5 is an enlarged view of part A of Figure 4, Figure 6
Figure 7 is a sectional view of the main parts showing the situation during operation,
FIG. 8 is an explanatory diagram of the operating characteristics of the present invention, FIGS. 9 and 10 are sectional views of main parts of a conventional pilot switching valve,
FIG. 11 is a hydraulic circuit diagram of FIG. 10, and FIG. 12 is an explanatory diagram of its operating characteristics. 1...Pilot switching valve, 4...Hydraulic pump,
16...Remote control valve, 22, 24...
...Pilot oil chamber, 23, 25...Pilot oil path, 27...Spool, 44, 45...Notch,
46, 47... Drain oil path, 48, 49... Throttle hole.

Claims (1)

[Claims] 1 In a pilot switching valve connected by a hydraulic remote control valve and a pilot oil line,
Slightly inward from both ends of the spool of the pilot switching valve, regardless of its stroke position,
It is always in communication with the drain oil passage of the pilot switching valve, and the position is such that when pilot pressure acts on one pilot oil chamber and the spool moves slightly, the other pilot oil chamber communicates with the drain oil passage of the pilot switching valve without resistance. A flow path consisting of a notch with a size of A switching valve characterized by being provided with a throttle hole that exhibits a predetermined throttle effect such that the capacity does not exceed the capacity of the switching valve.