JPS6256602A - Directional control valve - Google Patents

Abstract

PURPOSE:To increase the working speed and to prevent a time lag due to air by disposing notches on both side portions of a spool and providing throttle holes connecting both chambers and pilot oil chambers on both end axis portions of the spool. CONSTITUTION:Notches 36, 37 are disposed on both end portions of a spool 27, and throttle holes 45, 46 connecting the notches 36, 37 and the pilot oil chambers 22, 24 are provided on both right and left end axis portions of the spool 27. In this arrangement, at the initial stage of movement of the spool, the pilot oil chambers 22, 24 are instantaneously connected to a drain oil path through the notches 36, 37, so that working resistance of the spool 27 is decreased to increase the working speed. Furthermore, some oil in the pilot oil chambers 22, 24 is always let leak in drain oil paths 40, 41, so that oil is replaced to prevent a time lag due to a lowering of oil temperature and existence of air.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to the structure of a pilot switching valve controlled by a remote control valve for construction machinery.

Conventional technology A pilot switching valve controlled by a remote control valve is connected by a pilot oil passage L, and the pilot oil from the remote control valve acts on the pilot oil chambers on the left and right sides of the pilot switching valve to form a spool. It is designed so that it can be operated and switched. A hydraulic circuit using a conventional pilot switching valve is as shown in FIG. The remote control valve 16 is zM
Tv, the pilot switching valve 1' is controlled from a remote location, and the pilot oil from the remote control valve 16 acts on the pilot oil chamber 24' on the left side of the pilot switching valve 1°, for example, and operates the spool 27'. do. Then, the spool 27'' begins to move to the right, but at the same time, the oil in the pilot oil chamber 22'' on the opposite side returns to the oil tank 11 via the pilot oil path 23 and the remote control valve 16. In that case, the piping of the pilot oil passage 23 in the middle is long and has a small diameter. For this reason, considerable oil flow resistance occurs against the operation of the spool 27', especially in cold weather, so cuts 36° and 37° are provided on both sides of the spool 27', as shown in the cross-sectional view of Fig. 14. It is rare.

That is, the cuts of 37° and 36° cause the pilot oil chamber 24' and the drain oil passage 41 to open when the spool 27'' moves from side to side.
Alternatively, the pilot oil chamber 22° and the drain oil passage 40° are brought into communication for a short time.

Figures 15, 16, 17, 18, and 19 are all enlarged views of section A'' in Figure 14, and Figure 15 shows the spool 27'' in the neutral position. 16 shows a state in which the pilot oil chamber 22' and the drain oil passage 40' are communicated with each other while the spool 27' is moving to the right. As the spool 27'' moves to the right, the pilot oil chamber 2
A part of the oil in the drain oil passage 40' flows out into the drain oil passage 40'. 1st
Figure 7 shows the spool 27' moving to the right and reaching the stroke end, but the pyro oil chamber 22'' and the drain oil passage 40° remain in communication. Figure 18 shows the spool 27' moving to the right and reaching the stroke end. It shows a state in which the spool 27° has moved to the left and reached the left stroke end. Fig. 19 shows the spool 27° in the neutral position. Length from ° part to inner wall opening of drain oil passage 40"1' Length of notch 36' in Nisboul 27' S Distance of movement of Nispool 27' to the left and right CI Nisboul 27' is in the neutral position When the varnish spool 27' moves leftward and reaches the stroke end, the length that blocks the return oil passage 8' and the drain oil passage 40'. Length: Length from the outer wall of the valve body 38' to the inner wall of the return oil path 8° to the 8° part.

Problems to be Solved by the Invention Typically, pilot switching valves are controlled by remote control valves located remotely. For this reason, because the pilot oil passage piping is long and has a small diameter, there is considerable oil flow resistance when the spool is activated, resulting in a considerable time lag between remote control valve operation and spool movement. . Particularly in cold weather, the viscosity of the oil increases, the flow resistance in the pilot oil passage also increases, and it is also impossible to remove air that has entered the oil passage, resulting in a disadvantage that time lags tend to occur. Therefore, as shown in FIG. 14, in the prior art, notches 37'' and 36'' are provided on both sides of the spool 27°, so that when the spool 27' moves leftward or rightward, it is instantaneously cut out. However, as shown in Fig. 17, even when the spool moves and reaches the stroke end position, the pilot oil chamber and drain oil passage communicate with each other. The problem is that the length l' of the cut in the spool becomes large, and the overall length of the spool 27° and the hit of the valve body 38° become large. was there.

Means for Solving the Problems The means of the present invention taken to solve the above problems are as follows: (a) Notches are provided on both sides of the spool, and the pilot oil chamber and drain oil path are cut in the middle when the spool moves from side to side. When the mouth and spool move to the left or right and reach the stroke end, the spool cuts off communication between the pilot oil chamber and the drain oil path. , Set the length of the notches on both sides of the spool, and 3. Provide throttle holes in the axial center of both ends of the spool so that the notches communicate with the pilot oil chamber.

Effect A: At the beginning of the spool movement, the pilot oil chamber on the side pushed by the spool operation instantly communicates with the drain oil path through the notch, so some of the oil in the pilot oil chamber flows out to the drain oil path. Therefore, the operating resistance of the spool is low.
Fast operating speed.

B. A part of the oil in the pilot oil chamber can always leak into the drain oil path through the throttle holes in the axial center of both ends of the spool, except when the spool is near the stroke end of left-right movement. The oil is replaced and the time lag caused by a drop in oil temperature during cold weather can be prevented. In addition, air tends to flow out easily, and time lag due to the presence of air can be prevented.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In the hydraulic circuit diagram in Figure 1, oil passages 5, 6, and 7 are connected in parallel from the hydraulic pump 4 to ■ and 2.3, respectively.
In addition, these switching valves 1.2.3 are connected to the return oil path 8.9.1.
0 and each communicates with the tank 11. Reference numeral 12 indicates a return oil passage when in neutral, and 13 indicates an actuator.
is understood. Reference numeral 16 denotes a remote control valve, which includes left and right valve bodies 17, 18, and a lever device 19 for operating these valve bodies, and an oil passage 21 from an auxiliary hydraulic pump 20 communicates with the valve bodies 17, 18. A pilot oil passage 23 communicates from the left valve body 17 to the right pilot oil chamber 22 of the pilot switching valve 1, and a pilot oil passage 23 communicates from the right valve body 18 to the left pilot oil chamber 24 of the pilot switching valve 1. An oil passage 25 is in communication. Figure 2 shows pilot switching valve 1.
2.3, 27 is a spool of the pilot switching valve 1, both sides of which extend into the left and right pilot oil chambers 24, 22, and the right end connected to the spring via a spring receiver 28. 29, the left end portions are supported by springs 31 via spring receivers 30, respectively. In the center of the spool 27, only when the spool 27 is in the neutral position,
Return oil passage 12 for unloading pressure oil discharged from the hydraulic pump 4
Two notches 33 and 32 are provided symmetrically. Further, cutouts 35.34 are provided symmetrically on the outside thereof, and the cutouts 35.34 allow the oil discharged from the hydraulic pump 4 to flow into the first rf! In order to send the oil to the actuator 13 at J, the oil passage 5 is made to communicate with the oil passage 15 or the oil passage 14, and at the same time
5 to communicate with the oil passage 8. Further, cutouts 37 and 36 are provided symmetrically on the outside thereof.

The notches 37, 36 are for allowing the pilot oil chambers 24, 22 on the moved side to pass through the respective drain oil passages 41, 40 when the spool 27 moves to the left or right other than the neutral position. That is, the cuts 37, 36 allow the pilot oil chamber 24 to communicate with the drain oil passage 41 or the pilot oil chamber 22 with the drain oil passage 4o instantaneously when the spool 27 moves. Further, in the axial center of both left and right ends of the spool 27, there are throttle holes 46 that communicate the notch 37 and the pilot oil chamber 24, and
A throttle hole 45 is provided to allow the notch 36 and the pilot oil chamber 22 to communicate with each other. 3, 4, 5, 6, and 7 are all enlarged views of section A in FIG. 2, and FIG. 3 shows the spool 27 in the neutral position. FIG. 4 shows a state in which the pyro 7) oil chamber 22 and the drain oil passage 40 are communicated with each other while the spool 27 is moving to the right. By moving the spool 27 to the right, the pilot oil chamber 2
A part of the oil in 2 flows out to the drain oil path 40.

FIG. 5 shows a state in which the spool 27 has moved to the right and reached the stroke end, but the pilot oil chamber 22 and the oil passage 40 are blocked. FIG. 6 shows the spool 27 moving leftward and reaching the left stroke end.

In FIG. 7, the spool 27 is in the neutral position, and each symbol in the drawing is m: length from the outer wall A of the valve body 38 to the inner wall opening of the drain oil passage 40; 1 cut of the varnish boule 27; Length of 36 S Distance of movement of the varnish spool 27 to the left and right Cl Length of cutting the biloft oil chamber 22 and the drain oil passage 40 into four when the varnish spool 27 is in the neutral position Cz The varnish spool 27 moves to the left and stroke Length that blocks the return oil passage 8 and the drain oil passage 40 when reaching the end 2: This is the length from the outer wall part A of the valve body 38 to the inner wall part C of the return oil passage 8. Note that 26 is a relief valve, and 44 is a prime mover for driving a hydraulic pump.

The present invention is constructed as described above, and details of its operation will be described next. In the hydraulic circuit diagram of FIG. 1, when the actuator 13 is not operated and the lever device 19 is in the neutral position, the oil discharged from the auxiliary hydraulic pump 20 returns to the oil tank 11 from the relief valve 39. In addition, when the lever device 19 is in the neutral state, the notches 33 and 32 of the spool 27 are open to the return oil passage 12, and the oil discharged from the hydraulic pump 4 is 43 and returns to the oil tank 11. Next, when actuating the actuator 13, the lever device 19 is operated. For example, when it is tilted to the right (in the direction of the arrow), the oil discharged from the auxiliary hydraulic pump 20 passes through the oil passage 21, the valve body 18, and the pilot oil passage 25 and enters the pilot oil chamber 24, as shown in FIG. Push the spool 27 to the right against the spring 29. A notch 34 in the spool 27 allows the oil passage 14 and the oil passage 8 to communicate with each other, and a notch 35 allows the oil passage 5 and the oil passage 15 to communicate with each other. The actuator 13 operates because the oil passage 14 communicates with the oil tank 11 and the oil passage 15 communicates with the hydraulic pump 4. When the spool 27 moves to the right, the pilot oil chamber 22 on the right side communicates with the oil tank 11 via the pylon I, the oil passage 23, and the valve body 17, but the pilot oil passage 23 is narrow;
Moreover, since the pipe is long, the flow resistance within the pipe is large. However, since the spool 27 is in the neutral position, the drain oil passage 40 and the pilot oil chamber 22 are in communication through the notch 36 and the throttle hole 45, and at the beginning of the rightward movement of the spool 27, A notch 36 opens into the pilot oil chamber 22. Therefore, a small amount of oil in the pilot oil chamber 22 leaks into the drain oil passage 40 through the throttle hole 45, and
A portion of the oil in the pilot oil chamber 22 flows out into a drain oil passage 40 passing through the notch 36. With these, the spool 27
The resistance when moving is reduced, and the spool 27 moves further to the right, and when it reaches just before the stroke end, the fifth spool 27 moves to the right.
As shown in the figure, the pilot oil chamber 22 and the drain oil passage 40 are cut off. Furthermore, FIGS. 8, 9, and 10 all show other embodiments of the present invention. The one shown in FIG. 8 has oil fillers 47 opened at two locations on the outer periphery of the spool 27A instead of the notch 3G, and the two holes 47 are connected through holes 48. The dimension l between the openings is made slightly larger than the length m between the outer wall A of the valve body 38 and the inner wall opening of the drain oil passage 40. FIG. 9 shows the case of a spool 27B in which a notch 49 is provided instead of the notch 36. In the case shown in FIG. 10, the length E of the notch remains unchanged, but the throttle hole that makes the notch communicate with the axis of the spool end face is eliminated. However, valve body 3
8 is provided with a throttle hole 50 that communicates the viroft oil chamber 22 and the drain oil passage 40. Therefore, spool 27C
Regardless of the movement position, the pilot oil chamber 22 and the drain oil passage 40 are always connected through the throttle hole 50. Also,
The one shown in Fig. 11 is similar to Fig. 10, and the length of the cut is l.
is unchanged, but the aperture hole that connects the notch to the axis of the spool end face has been eliminated. The valve body 38 in FIG. 10 has a throttle hole 50, whereas the valve body 38 in FIG. 11 has a small groove (slit) 51 extending from the notch 36 toward the right end surface of the spool 27D. It is.

The length 2' of the small groove 51 is a length that allows the biloft oil chamber 22 and the drain oil passage 40 to be opened until the spool 27D moves leftward and reaches the stroke end.

Therefore, in the case of FIG. 11 as well, the pilot oil chamber 22 and the drain oil passage 40 are always in communication through the small groove 51, regardless of the moving position of the spool 27D. For that purpose, the first
The hydraulic function of the pilot switching valve shown in FIGS. 0 and 11 is as shown in FIG. 12. That is, even when the spool moves left and right and reaches the left or right stroke end position, the pyro oil chamber and the drain oil passage remain open at the throttle hole or small groove.

Effects of the Invention As described above, in the present invention, notches are provided on both sides of the spool of a viroft switching valve controlled by a remote control valve, and throttle holes are provided that communicate with the notches and the axial center portions of both ends of the spool. The spool is actuated and moved by pilot pressure, and when it reaches a position near the stroke end, the structure is such that communication between the pilot oil chamber and the drain oil passage is cut off. However, in the prior art, the spool 27 is operated and moved by pilot pressure.
As shown in FIG. 17, even when the stroke end position is reached, the pilot oil chamber 22' and the drain oil passage 40'' are in communication.Therefore, the length l' of the cut 36' becomes considerably large. In contrast, in the pilot switching valve of the present invention, as shown in FIG. The length l of the notch 36 is small.Since both sides of the pilot switching valve are symmetrical, the total length of the spool 27 of the present invention is shorter than the total length of the spool 27' of the conventional one (f'
It can be shortened by 1×2. On the other hand, let us compare all the valve bodies of the virofft switching valves of the present invention and those of the prior art. As shown in FIG. 19, the outer wall A' of the prior art valve body 38' and the inner wall of the return oil passage 8'.

The length 6 with the part is H2s, C! -1-S+ l +c, , ll+■. On the other hand, in the case of the present invention, similarly h is W+=Cz
＋S All cars with body 38 are connected from valve body 38'
(It can be made smaller by x2 than 1'-1. Therefore, the pilot switching valve of the present invention is smaller and lighter than that of the prior art, and costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of the present invention, Fig. 2 is a sectional view of the virofloft switching valve of the present invention, and Figs. 3, 4, 5, 6, and 7 are all Fig. 2. FIG. 8, FIG. 9, FIG. 10, and FIG. 11 are all enlarged views of section A in FIG. Fig. 12 is a hydraulic function diagram of the pilot switching valve shown in Figs. 10 and 11, Fig. 13 is a hydraulic circuit diagram of the prior art, Fig. 14 is a sectional view of the pilot switching valve of the prior art, and Figs. Figures 16, 17, 18, and 19 are all
This is an enlarged view of section A in FIG. 4, which is an example of the prior art. 1...Pilot switching valve 8...
...Return oil path 16...Remote control valve 22.2
4...Pilot oil chamber 23.25...Pilot oil path 27...Spool 36.37...Depth of cut 40.41...Drain oil path 45.46... ...Aperture hole 50...Aperture hole 51...More than small groove

Claims (1)

[Claims] (1) In a pilot switching valve connected to a remote control valve by a pilot oil passage, when pilot hydraulic pressure acts on the opposite side of the spool at a position slightly inward from both ends of the spool of the pilot switching valve. , a cut that connects the pilot oil chamber and drain oil passage for a short time,
and a switching valve characterized by a configuration in which a throttle portion is provided that communicates the notch with the pilot oil chamber, and the spool blocks communication between the pilot oil chamber and the drain oil path at a stroke end position of the spool. structure.