JPS6346311B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a pilot section of a pilot switching valve controlled by a remote control valve.

For pilot switching valves that are controlled by a remote control valve, the two are connected by a pilot oil passage, and the pilot oil from the remote control valve acts on the left and right pilot chambers of the pilot switching valve, causing the spool to flow. It operates to switch this. Since a remote control valve normally controls a pilot switching valve from a remote location, its pilot oil path is also long, and since it does not require a large amount of oil just to operate the spool, the pilot oil path is shortened. The diameter of the pipe is not that large. Because the pilot oil passage piping is long and small in diameter, the spool does not operate as quickly, but
Strictly speaking, there is considerable oil flow resistance when the spool is activated, which causes a time lag. Particularly in cold weather, the viscosity of the 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 creates an opportunity to remove the air trapped in this pilot oil passage. Since it is small, it is easy to create a bad condition where a time lag occurs.

The object of the present invention is to solve the above problems and provide an apparatus that does not cause time lag during pilot operations.

The structure of the present invention is such that in a pilot switching valve through which a pilot oil passage passes from a remote control valve, when pilot pressure acts on the spool of the pilot switching valve in one pilot oil chamber and the spool moves, the other pilot oil chamber A flow path is provided that communicates the return oil path in the valve body with the return oil path in the valve body.

When the pilot oil chamber communicates with the tank side through the pilot oil passage, it also communicates with the return side oil passage inside the valve body, so the resistance of the return oil passing through the pilot oil passage can be reduced and the occurrence of time lag can be prevented. . Furthermore, since oil can flow, air in the pilot oil passage can easily escape to the outside.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Reference numerals 1, 2, and 3 are all pilot switching valves, and oil passages 5, 6, and 7 from a hydraulic pump 4 are connected in parallel to these pilot switching valves 1, 2, and 3, respectively. 2 and 3 communicate with the tank 11 through return oil passages 8, 9, and 10, respectively. In addition, 12 is a return oil passage at the time of neutrality, and 13 is an actuator, and oil passages 14 and 15 communicate with the pilot switching valve 1 to the actuator 13. Reference numeral 16 denotes a remote control valve, which includes left and right valve bodies 17 and 18, and a lever device 1 for operating the same.
9, and an oil passage 21 from an auxiliary hydraulic pump 20 communicates with the valve bodies 17 and 18. Further, 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 from the right valve element 18 to the left pilot oil chamber of the pilot switching valve 1. 24 has a pilot oil passage 25
is understood. Note that 26 is a relief valve.

Fig. 2 shows the inside of the pilot switching valves 1, 2, and 3, and Figs. 3, 4, 5, 6, and 7 show the operation and embodiments of the part shown by arrow A in Fig. 2. In this enlarged view, 27 is a spool, whose both ends face the left and right pilot oil chambers 24, 22, the right end is connected to the spring 29 via the spring receiver 28, and the left end is connected to the spring receiver 30. It is supported by a spring 31 via. The spool 27 has a central part of the spool 27.
There are two symmetrical notches 32 and 33 that open the return oil passage 12 only when the is in the neutral position, and an oil passage 14 that connects the oil passage 5 that communicates with the pump 4 to the actuator 13 is located on the outside thereof. Alternatively, there are symmetrical cuts 34 and 35 in the oil passage 15 and at the same time, the oil passage 8 communicating with the tank 11. Furthermore, a return oil passage 8 and another switching valve 2 are arranged outwardly.
Notches 36 and 37 are provided symmetrically on the left and right to open the return oil passages 9, but the notches 36 and 37 not only open the return oil passages 8 and 9, but also open the return oil passages 8 and 9 when the spool 27 is in a position other than neutral. The oil passage 8 is formed so as to communicate with the pilot oil chamber 22 or 24, and when the spool 27 moves to the right, the pilot oil chamber 22 communicates with the oil passage 8 through the notch 36, and when the spool 27 moves to the left, it communicates with the oil passage 8. The pilot oil chamber 24 communicates with the oil passage 8 via the notch 37.

The present invention is constructed as described above, and when the actuator 13 is not operated 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 26, and the oil in the pilot oil path 23, Since the pilot oil chambers 22 and 24 communicate with the tank 11 through 25, the spool 27 is held in the neutral position by the springs 29 and 31, and only the return oil passage 12 in the neutral state is opened by the notches 32 and 33. The pressure oil from the hydraulic pump 4 returns to the tank 11 through the return oil path 12 at the time of neutralization.

Next, when actuating the actuator 13, the lever device 19 is operated. For example, the right side (arrow direction)
When it is tilted down, oil from the auxiliary hydraulic pump 20 flows into the pilot oil chamber 24 through the valve body 18 and the pilot oil passage 25, pushing the spool 27 to the right against the spring 29. The pilot oil chamber 22 communicates with the return oil passage 8 through the notch 36 . Spool 27
The oil in the pilot oil chamber 22 pushed by the entry of the oil not only flows from the pilot oil passage 23 through the valve body 17 to the tank 11, but also partially flows from the notch 36 through the oil passage 8 to the tank 11. . Both the pilot oil passage 23 and the return oil passage 8 of the switching valve 1 communicate with the tank 11, so the oil pressure in the pilot oil chamber 22 is almost gone, and the spool 27 moves against the spring 29. In this process, one side is connected to the tank 11 through the thin and long pilot oil passage 23 and further through the valve body 17, which has a large internal resistance, and the other side is connected to the tank 11 through the return oil passage 8 of the switching valve 1. Since the flow path is large and short, its internal resistance is small, and a notch 36 is provided to allow oil in the pilot chamber 22 to flow through the oil path 8 into the tank 1.
1 has a great effect. In particular, when the spool 27 is moved by pressure oil, the operating speed is fast and the cross-sectional area of the spool 27 is larger than the cross-sectional area of the pilot oil passage 23.
However, providing a notch 36 in the spool 27 to release some of the oil in the pilot oil chamber 22 to the oil path 8 simply creates a separate return oil path. This is significant because it not only provides a return oil passage that is more effective than the pilot oil passage 23.

The notch 36 provided in the spool 27 is the same as the notch 36 shown in FIG. 3 because it is only necessary to allow the oil chamber 22 to pass through the oil passage 8 when the spool is pushed toward the pilot oil chamber 22. Instead, the spool 27 as shown in Fig. 6 is connected to the pilot oil chamber 22.
The object of the present invention can also be achieved by providing an oil passage 38 that allows the oil chamber 22 and oil passage 8 to communicate only when pushed to the side, or an axial oil groove 39 as shown in FIG. can be achieved.

As described above, the present invention provides a system in which when the spool of a pilot switching valve connected to a remote control valve by a pilot oil passage is pushed by pilot pressure, the pilot oil chamber on the opposite side and the tank of the switching valve Since the flow passage communicating with the port is provided, the oil flows out from the pilot oil chamber quickly, and there is no time lag even when the oil resistance in the pilot oil passage increases in cold weather. In addition, since the pilot oil chamber communicates with the outside at two locations, oil circulation is improved, air is easily released from the pilot oil passage to the outside, and time lags due to the presence of air can be prevented.

[Brief explanation of the drawing]

The drawings are all embodiments of the present invention, but the first
The figure is a hydraulic circuit diagram, Figure 2 is a cross-sectional view, Figure 3 is an enlarged view of section A in Figure 2, Figures 4 and 5 are diagrams showing the operating situation in Figure 3, FIGS. 6 and 7 are diagrams showing other embodiments of the present invention. 1...Pilot switching valve, 8...Oil passage, 16...
...remote control valve, 22...pilot oil chamber, 23...pilot oil passage, 24...pilot oil chamber, 25...pilot oil passage, 27...spool, 36...notch, 37...notch.

Claims (1)

[Claims] 1. In a pilot switching valve connected to a remote control valve by a pilot oil passage, pilot pressure is applied to one pilot oil chamber of the pilot switching valve at a position slightly inward from both ends of the spool of the pilot switching valve. A switching valve characterized in that a flow passage is provided such that when the spool is moved slightly by operation, the other pilot oil chamber communicates with a return oil passage of the pilot switching valve.