JP2001248603A - Directional control valve having regeneration circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a directional control valve having a regeneration circuit capable of achieving a regeneration function by operation of a spool in one direction, and preventing backflow of pressure oil by operation of the spool in the opposite direction even with a spool type comprising a flow controlling notch opened in a load port. SOLUTION: An oil passage 52 directly opened in a load port Ba is provided on a spool 22, and an inward flow check valve 54 having a valve element 60 to control opening/closing to the oil passage 52 and an oil passage 51 is provided in the spool 22. An oil passage 53 opened in a tank port T1 when the spool 22 is operated left in an illustration is provided, a restrictor 70 to communicate the oil passage 52 with a spring chamber 65 inside the valve element 60 and a restrictor 71 to communicate the spring chamber 65 with the oil passage 53 are provided on the valve element 60 of the check value 54, and an opening area of the restrictor 70 is set to be smaller than an opening area of the restrictor 71.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional control valve having a regenerative circuit, and more particularly to a directional control valve having a regenerative circuit used for a construction machine such as a hydraulic shovel performing a work in which a negative load is applied by its own weight.

[0002]

2. Description of the Related Art An example of an operation in which a negative load due to its own weight acts on a hydraulic excavator is a surface compaction operation. In this rolling work, as shown in FIG. 4, the boom 100 is lowered and the bucket 10 provided at the tip of the arm 101 is moved.
2. Put your back on the ground. In this rolling work, bucket 1
02, the boom 100, the arm 101, and the bucket 1 in the initial stage of the lowering operation of the boom 100 before the back of the boom 100 hits the ground surface.
02 acts on the boom cylinder 10 as a negative load.
The rod 10a is forcibly pushed down by this negative load and tends to descend. At this time, if the amount of oil sent from the hydraulic pump to the rod side of the boom cylinder 10 is larger than the oil amount corresponding to the descending speed of the rod 10a, the rod 1
At the same time, the cylinder tube 10b receives an upward force as indicated by a broken-line arrow A, while the cylinder tube 10b receives a downward force as indicated by a solid-line arrow A. Here, the cylinder tube 10
Since b is pin-connected to the shovel body, when an upward force acts on the cylinder tube 10b, this force causes the front part of the shovel body to rise as indicated by the solid line arrow C, resulting in deterioration of operability.

To eliminate this problem, the boom cylinder 10
It is not necessary to send pressure oil from the hydraulic pump to the rod side of the boom 100.
After 2 hits the ground, it is necessary to compress the boom cylinder 10 with pressure oil from a hydraulic pump and press the bucket 102 against the surface of the ground.

In order to solve such a problem, at the beginning of the boom lowering, a part of the oil returned from the bottom side of the boom cylinder 10 to the tank is returned to the rod side of the boom cylinder 10 so that the boom lowering speed becomes constant. A directional control valve having a regeneration circuit for sending pressure oil from a hydraulic pump to the rod side of the boom cylinder 10 has also been proposed.

FIG. 5 shows a conventional example of a closed center type load sensing valve. This directional control valve is disclosed in Japanese Utility Model Laid-Open No. 5-81509.

In FIG. 5, when the spool 211 of the directional control valve 201 is moved to the right in the drawing, the pressure oil on the bottom side 11 of the boom cylinder 10 is initially supplied to the directional control valve 2 when the boom is lowered.
At the same time as the fuel is returned from the load port 206 to the tank port 208, it also flows from the regeneration port 216 to the load port 207 from the recycled oil passage 217 via the check valve 218 to fill the rod side 12 of the boom cylinder 10. .
The directional control valve 201 has two pump ports 20.
When the spool 211 is moved rightward in the figure, the pump port 203 and the feeder port 205 communicate with each other. Therefore, load port 206 and regeneration port 2
By adjusting the relationship between the flow control notch 16 and the flow control notch between the pump port 203 and the feeder port 205, the supply of hydraulic oil from the hydraulic pump is delayed, and when the boom lowering speed becomes constant, the hydraulic pressure is reduced. Pressure oil can also be sent from the pump to the rod side of the boom cylinder 10.

When the bucket 102 comes into contact with the ground surface and rolls, the movement of the boom cylinder 10 stops, and the bottom side 11
The pressure on the rod side 12 increases on the contrary, but the pressure oil does not flow backward due to the action of the check valve 218.

When raising the boom by moving the spool 211 to the left, the pressure oil of the hydraulic pump flows from the pump port 202 to the feeder port 204 and is supplied to the bottom side 11 of the boom cylinder 10 and the rod side 12 of the boom cylinder 10 Is returned from the load port 207 of the directional control valve 201 to the tank port 209. At this time, since the connection between the load port 206 and the reproduction port 216 is cut off, no malfunction occurs. Next, a conventional example of a so-called open center type directional control valve having a center bypass oil passage will be described with reference to FIG. This is an example of application to an actual machine.

In FIG. 6, oil discharged from a hydraulic pump 20 is supplied to a pump port P, and a downstream side of the pump port P is provided in a directional control valve 21A in a center bypass port Pb.
And a parallel port Pp. The center bypass port Pb further includes right and left bypass ports Pbr and Pb.
1 and the parallel port Pp further branches to the right and left feeder passages Fr and Fl, and the port Pp and the passages Ppr and Pl.
A hold check valve 23 is disposed between the pl.

Around the spool hole where the spool 22A of the valve body 21a slides, lands 1 and
Next to it, the right tank port Tr, land 2, next to the right load port Aa, land 3, next to the right feeder port Ppr, and the center center bypass ports Pb, Pb.
r, left side feeder port Ppl across Pbl,
A land 4, a left load port Ba and a land 5, and a left tank port T1 and a land 6 are formed next to the land 4 and the land 5, respectively.

The spool 22A has right and left load ports Aa,
Ba has a large diameter portion 7, and lands 3 and 4 have meter-in flow control notches 22 a and 22 b formed in lands 3 and 4, and lands 2 and 5 have meter-out flow control notches 22 c and 22 c. A small diameter portion 8 is formed at the right and left feeder ports Ppr and Ppl and the tank ports Tr and Tl. Notch 2 for lands 3 and 4
2a, 22b and notches 22c at the lands 2, 5;
22d is a feeder port Ppr, Ppl and a tank port Tr, a small diameter portion 8 of the spool 22A.
Open to Tl.

When lowering the boom cylinder 10 when the spool 22A is moved to the left from the illustrated position,
Connect the load port Aa to the bottom side 11 of the boom cylinder 10
And the load port Ba is connected to the rod side 1 of the boom cylinder 10.
Connect to 2. When the spool 22A is moved to the left, the notch 22c of the land 2 portion connects the port Aa and the port Tr, and the notch 22b of the land 4 portion connects the port Ppl and the port Ba.

The bottom side 11 of the boom cylinder 10
The non-return valve 16 provided in the pipe is an anti-drift valve for drop prevention which operates by a hydraulic signal of the remote control valve 15.

The direction control valve 21A is provided with a regeneration circuit as follows.

An axial oil passage 32 is provided in the spool 22A, a radial oil passage 30 perpendicular to the oil passage 32 is provided in the land 2 portion, and a similar oil passage 31 is provided in the land 1 portion. The check valve 24. Further, a radial oil passage 33 is provided in the land 4 portion, and the oil passage 32
And a check valve 25 is arranged between 33 and 33.

When the spool 22A is moved to the left in the figure,
The pressure oil from the bottom side 11 of the boom cylinder 10 returns to the load port Aa, and the notch 22c of the land 2 portion
Through the oil passage 3
Part of the pressure oil guided from 0 to the oil passage 32 is returned to the tank port Tr via the check valve 24 and the oil passage 31,
The rest is via the check valve 25 and the oil passage 33 through the load port Ba.
To regenerate to the rod side 12 of the boom cylinder 10. Even if the rod side 12 of the boom cylinder 10 becomes high pressure in this state, the discharge oil of the hydraulic pump 20 flowing into the port Ba does not flow backward to the port Aa by the function of the check valve 25.

When the operation spool 22A is operated rightward in the drawing by raising the boom, the oil passage 33 is connected to the feeder port Ppl and the oil passage 30 is connected to the tank port Tr. Feeder port Ppl
Pressure oil (discharge oil of the hydraulic pump 20) flows into the tank port Tr
There is no backflow to.

There are two types of open center type directional control valves in a spool that slides in the valve body.
One is the type shown in FIG. 6 described above, and the other is the type shown in FIG.
It is a type shown in FIG.

The spool 22A shown in FIG. 6 has the large diameter portion 7 at the right and left load ports Aa and Ba as described above, and the notches 22a and 22b at the lands 3 and 4 and the lands 2 and 5 The notches 22c and 22d of the feeder port P are formed at the small diameter portion 8 of the spool 22A.
Opened to pr, Ppl and tank ports Tr, Tl. On the other hand, the spool 22B in FIG.
a and Ba are small-diameter portions 8B.
The notches 22a and 22b of the portion 4 and the notches 22c and 22d of the lands 2 and 5 are both open to the load port Aa or Ba at the small diameter portion 8B.

FIG. 7 shows that, when the spool 22B is moved to the left from the position shown in the drawing, when the boom cylinder 10 is lowered, the load port B is connected to the boom cylinder 10 in a manner opposite to that shown in FIG. , The load port A is connected to the rod side 12 of the boom cylinder 10. When the spool 22B is moved to the left, the notch 22a of the land 3 connects the port Ppr to the port Aa, and the notch 22d of the land 5 connects the port Ba and the port Tl.

[0021]

As described above, both the closed center type directional control valve and the open center type directional control valve having a regeneration function are known.

However, in the case of the closed center type directional control valve shown in FIG. 5, the center portion in the spool 11 is already used for load pressure detection by providing a load pressure detection passage (not shown). The spool 1 for playback
The central part within 1 cannot be used. For this reason,
As shown in the figure, the oil passage 17 for regeneration must be provided in the valve body, and there is a problem in simplification of equipment.

In the case of an open center type directional control valve,
There are no such restrictions. For this reason, as shown in FIG. 6, the central portion in the spool can be used as the oil passage 32 for regeneration, and the equipment can be simplified as compared with the closed center type.

However, as described above, the directional control valve of the open center type is divided into two types depending on the design of the spool, and the type shown in FIG.
a, 22b, 22c, 22d are load ports Aa or Ba
Directional control valve 21 having a spool type that opens to the side
If an attempt is made to provide a regeneration circuit similar to the direction control valve 21A of FIG.

FIG. 7 shows a case where a regeneration circuit similar to the direction control valve 21A of FIG. 6 is provided, and the state is indicated by a two-dot chain line. An axial oil passage 32 is provided in the spool 22B, a radial oil passage 30 perpendicular to the oil passage 32 is provided in the land 4, and a similar oil passage 31 is provided in the land 5 in the reverse direction. The stop valve 24 is arranged. A radial oil passage 33 perpendicular to the oil passage 32 is provided at the land 2, and the check valve 25 is disposed between the oil passage 32 and the oil passage 33.

The operation of lowering the boom by moving the spool 22B to the left in the drawing is the same as in FIG. 6, and there is no particular problem. That is, the return oil from the bottom side 11 of the boom cylinder 10 is regenerated to the rod side 12 of the boom cylinder 10, and no backflow of the pressure oil occurs even when the rod side 12 becomes high pressure. However, with the operation of raising the boom to move the spool 22B rightward in the figure, the oil passage 30 is moved to the feeder port Ppl.
Is connected to the tank port Tr, the oil discharged from the hydraulic pump 20 supplied to the feeder port Ppl escapes from the tank port Tr to the tank through the oil passages 30, 32, and 33. I will. For this reason, pressure oil cannot be supplied to the bottom side of the boom cylinder 10, and the boom cannot be raised.

If the boom directional control valve is of the type shown in FIG. 6, such a problem does not occur. But,
2. Description of the Related Art In construction machines such as hydraulic excavators, directional control valves of a plurality of non-driving members such as a boom, an arm, and a bucket are arranged in the form of a multiple valve. In this case, using the multiple direction valve of the type shown in FIG. 7 as the direction control valve of FIG. 7 and using only the direction control valve of the boom type shown in FIG. 6 makes it possible to lower the boom by operating the spool to the left in the drawing. Therefore, it is necessary to reverse the two pipes connecting the boom cylinder and the valve. That is, in the directional control valve of the type shown in FIG. 6, the rod-side pipe of the boom cylinder 10 is connected to the load port A and the bottom pipe is connected to the load port B in the directional control valve of the type shown in FIG. Connect the rod side piping of cylinder 10 to load port B
, And the bottom pipe must be connected to the load port A. When the pipes connected to the load ports A and B are reversed as described above, the connection work of the pipes is complicated and error-prone. Also, a directional control valve other than the boom in the multiple valve (FIG. 7)
When the spool 22B is operated leftward in the figure, the pressure oil flows out of the load port A, but only the boom directional control valve (type in FIG. 6) flows out of the load port B. , Service, and inspection may cause confusion.

In the type shown in FIG. 7, if the land 2 is sufficiently long, there is no possibility that the oil passage 33 is connected to the tank port Tr. However, the notch 22c in the land 2 part becomes long, and not only the spool shape of the land 2 part needs to be reconsidered, but also the position of the tank port Tr differs only in the boom direction control valve in the multiple valve. Also, the connection of the tank port Tr needs to be reconsidered.

An object of the present invention is to provide a regenerative function in one-way operation of a spool and a reverse flow of pressurized oil in an opposite operation of a spool, even if the notch for flow rate control is a spool type opening to a load port. It is to provide a directional control valve with no regeneration circuit.

[0030]

(1) In order to achieve the above object, the present invention provides a first oil passage in which return oil from a return load port is provided in the spool during one-way operation of the spool. And a directional control valve having a regeneration circuit that recirculates to the supply-side load port via the first check valve, wherein a second inflow of inward flow between the return-side load port and the first oil passage in the spool is provided. A check valve is provided, and an opening / closing control means for opening the second check valve when the spool is operated in one direction and closing the second check valve when operating the spool in the opposite direction is provided.

By providing the second check valve for inward flow and the opening / closing control means as described above, the second check valve opens when the spool is operated in one direction, and can perform a regeneration function. The second check valve closes and no backflow of pressure oil occurs.

(2) In the above (1), more specifically, the spool is provided with a second oil passage directly opening to the return side load port, and the second check valve is connected to the second oil passage and the second oil passage. A valve body for controlling opening and closing with the first oil passage, wherein the opening and closing control means is provided on a valve body of the second check valve, and communicates the second oil passage with a spring chamber inside the valve body; First
A second throttle provided on the valve body of the check valve for communicating the spring chamber with the tank port when the spool is operated in one direction; Is smaller than the opening area.

Thus, the opening / closing control means opens the second check valve when the spool is operated in one direction, and closes the second check valve when the spool is operated in the opposite direction.

That is, when the spool is operated in one direction, the second throttle of the opening / closing control means connects the spring chamber to the tank port, so that the return load port → the second oil passage → the first throttle → the spring chamber → the second throttle. Throttle → The oil passage of the tank port is formed.
Since the opening area of the throttle is smaller than the opening area of the second throttle, the pressure in the spring chamber is substantially the same as that of the tank port. Therefore, the differential pressure between the pressure of the return load port and the pressure of the tank port acts on the valve body of the second check valve, and opens the second check valve.
When the spool is operated in the reverse direction, the second throttle of the opening / closing control means does not allow the spring chamber to communicate with the tank port, so that the spring chamber has the same pressure as the return-side load port, and the second check valve is kept closed.

(3) In the above (2), preferably, the opening / closing control means is formed on the spool,
A third oil passage that opens to the tank port when the spool is operated in one direction; the second throttle opens to the third oil passage;

Thus, the second throttle of the opening / closing control means allows the spring chamber to communicate with the tank port when the spool is operated in one direction, and does not allow the spring chamber to communicate with the tank port when operating the spool in the opposite direction.

[0037]

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

In FIG. 1, reference numeral 21 denotes a directional control valve having a regeneration circuit according to the present embodiment.
1 has a valve body 21a formed with a pump port P to which the discharge oil from the hydraulic pump 20 is supplied, and load ports A and B for supplying and discharging the pressure oil to and from the boom cylinder 10, and downstream of the pump port P The side is branched into a center bypass port Pb and a parallel port Pp in the valve body 21a, the center bypass port Pb is further branched into right and left bypass ports Pbr and Pbl connected to the tank T, and the parallel port Pp is further right and left feeder passage. Branch to Fr, Fl,
A hold check valve 23 is arranged between the parallel port Pp and the feeder passages Fr and Fl.

The valve body 21a has a spool hole 21b.
Is formed, and the spool 22 is inserted into the spool hole 21b. The bypass ports Pb, Pbr, and Pbl are formed around the spool hole 21b. The right and left sides of the bypass port Pb, Pbr and Pbl are connected to the land 1, the right tank port Tr connected to the tank T, the land 2, and the load. A right load port Aa connected to the port A, a land 3, and a right feeder port Ppr connected to the feeder passage Fr are formed, and bypass ports Pb and Pbr, P
A left feeder port Ppl connected to the feeder passage Fl, a land 4, a left load port Ba connected to the load port B, a land 5, a left tank port Tl connected to the tank T, and a land 6 are sequentially formed on the left side of the drawing bl. .

The spool 22 has right and left tank ports Tr,
T1 has a large-diameter portion 7 and right and left load ports Aa,
The portions of Ba and feeder ports Ppr, Ppl are small diameter portions 8B, 8B.
Notches 22a, 22 for meter-in flow rate control
b is formed, and notches 22c and 22d for meter-out flow control are formed in the lands 2 and 5 of the spool 22, and the notches 22a and 22b in the lands 3 and 4 and the notches in the lands 2 and 5 are formed. Reference numerals 22c and 22d open to the load ports Aa and Ba at small diameter portions 8B and 8B, respectively. The load port A is connected to the rod side 12 of the boom cylinder 10, and the load port B is connected to the bottom side 11 of the boom cylinder 10. When the spool 22 is moved to the left from the position shown, the notch 2
2a connects the feeder port Ppr and the load port Aa, the notch 22d of the land 5 connects the load port Ba and the tank port Tl, and pressurized oil is supplied / discharged in the contraction direction of the boom cylinder 10 to perform the boom lowering operation. . Conversely, when the spool 22 is moved to the right in the figure, the notch 22b of the land 4 is moved to the feeder port Ppl and the load port Ba.
The notch 22c of the land 2 connects the load port Aa and the tank port Tr, and the boom cylinder 10
Pressure oil is supplied and discharged in the direction of extension of the boom, and the boom is raised.

The spool operation of the direction control valve 21 is performed by the remote control valve 15. When the remote control valve 15 is operated to generate the hydraulic signal Pa, the spool 22 moves to the left in the figure, and when the remote control valve 15 is operated to generate the hydraulic signal Pb, the spool 22 moves to the right in the figure.
In the piping on the bottom side 11 of the boom cylinder 10, there is provided a check valve 16 as an anti-drift valve for drop prevention, which is operated by a hydraulic signal Pa of the remote control valve 15.

The direction control valve 21 has a regeneration circuit 50 incorporated therein. The reproduction circuit 50
And an axial oil passage 51 provided inside the spool 2.
2, a load port B provided at the small diameter portion 8B on the left side of the drawing.
a, which opens directly on the outer periphery of the spool 22, and is closed by the land 5 when the spool 22 is in a neutral position, and opens to the tank port Tl when the spool 22 moves to the left in the drawing (during regeneration). An oil passage 53, a check valve 54 provided between the oil passage 51 and the oil passages 52 and 53, an opening on the outer periphery of the spool 22, and closed by the land 2 when the spool 22 is in neutral, An oil passage 55 that opens to the load port Aa when moving to the left in the drawing (during regeneration);
Check valve 56 provided between oil passage 51 and oil passage 55
And

The check valve 54 opens when the spool 22 moves to the left in the drawing (during regeneration), allows the flow of pressure oil from the oil passage 52 to the oil passage 51, and reduces the excess flow rate of the return oil. It returns to the tank port T1 from the passage 53, and the spool 2
2 is closed at the time of the right operation in the figure, and the return oil flows through the oil passages 51 and 5.
It is configured such that none of the three flows in. The check valve 56 is a normal check valve that opens when the spool 22 moves to the left in the drawing (during regeneration) and allows the flow of pressure oil from the oil passage 51 to the oil passage 55.

The details of the check valves 54 and 56 will be described with reference to FIG.

In FIG. 2, the above-described axial oil passage 51 is formed in a portion of the spool 22 except for both ends of the spool, and has a larger diameter than the oil passage 51 closed by plugs 63l and 63r at both ends of the spool. End holes 60l and 60r are formed. The oil passage 52 directly opening to the load port Ba is connected to the oil passage 51 and the end hole 601 in the spool 22.
The oil passage 53 which opens on the step surface at the boundary between the spool 22 and the outer periphery of the spool 22 is formed with a groove 5 having a predetermined width formed on the outer periphery of the spool 22 where the end hole 601 of the spool 22 is located.
3a and a radial hole 53b communicating with the groove 53a and opening on the inner peripheral surface of the end hole 60l.

The check valve 54 is disposed slidably in the axial direction in the end hole 601, and controls the opening and closing of the oil passage 52 and the oil passage 51, and the end hole 601 of the oil passage 51. A seat portion 61 formed at the opening to
A spring 62 for urging the valve body 60 in a seating direction (a valve closing direction) with the seat portion 61; a cylindrical guide portion 64 on the side opposite to the seat portion of the valve body 60; A spring chamber 65 in which the spring 62 is located is formed by the inside of the shape guide portion 64 and the plug 63l.

The valve body 60 has a pressure receiving portion 66 radially outside the seat portion 61 and a pressure receiving portion 67 radially inside the seat portion 61. The oil passage 52 is formed on the pressure receiving portion 66 side. It opens to the pressure receiving chamber 68, and the pressure receiving portion 67 is located in the oil passage 51 in the axial direction. That is, the check valve 54 is configured as an inward flow check valve in which the pressure oil flows from the oil passage 52 to the oil passage 51.

The pressure receiving chamber 66 is provided at the pressure receiving portion 66 of the valve body 60.
A hole 70 is formed as a first throttle that allows the spring chamber 8 to communicate with the spring chamber 65.
A hole 71 as a second throttle and an outer peripheral groove 72 for communicating the oil passage 5 with the oil passage 53 are formed. The hole 71 connects the spring chamber 65 to the outer peripheral groove 72 and the oil passage when the spool 22 moves to the left in the drawing (during regeneration). It communicates with the tank port Tl via 53. Here, the opening area of the hole 70 (first stop) is set smaller than the opening area of the hole 71 (second stop).

On the other hand, on the right side of the drawing, the oil passage 55 opened on the outer periphery of the spool 22 is
0r is formed at a portion where the check valve 56 is located, and the check valve 56 includes a valve body 80 slidably disposed in the end hole 60r in the axial direction.
The valve body includes a seat portion 81 formed at an opening to the end hole 60r of the oil passage 51, and a spring 82 for urging the valve body 80 in a seating direction (valve closing direction) with the seat portion 81. A side opposite to the seat portion of 80 is a cylindrical guide portion 84, and a spring chamber 85 in which a spring 82 is located is formed by the inside of the cylindrical guide portion 84 and the plug 63r in the end hole 60r.

The valve element 80 has a pressure receiving portion 86 radially outside the seat portion 81 and a pressure receiving portion 87 radially inside the seat portion 81. The oil passage 55 is formed on the pressure receiving portion 86 side. It opens to the pressure receiving chamber 88, and the pressure receiving portion 87 is located in the oil passage 51 in the axial direction. That is, the check valve 56 is configured as an outward flow check valve in which the pressure oil flows from the oil passage 51 to the oil passage 55. A hole 90 that connects the spring chamber 85 to the pressure receiving chamber 88 is formed in the pressure receiving portion 86 of the valve body 80.

The operation of the present embodiment configured as described above will be described.

First, when the spool 22 is at the illustrated neutral position, the spring chamber 65 of the check valve 54 is connected to the load port Ba.
And the oil passage 52, the pressure receiving chamber 68, and the hole 70 (first throttle), and the spring chamber 65 communicates with the oil passage 53 through the hole 71 (second throttle). However, at this time, the communication between the oil passage 53 and the tank port Tl is blocked by the land 5 of the spool 22, and the spring chamber 65 has the same pressure as the load port Ba. On the other hand, at this time, the pressure in the oil passage 51 is almost equal to the tank pressure (0 Bar). Therefore, the check valve 54 is in the closed state.

When the spool 22 is moved to the left in the figure to start the boom lowering operation, the spool 22 is moved to the left in the figure, and when the oil passage 53 communicates with the tank port Tl, the load port Ba → the oil passage 52 → Pressure receiving chamber 68 → hole 70 (first throttle) → spring chamber 65 → hole 71 (second throttle) → oil passage 53 →
An oil passage for the tank port Tl is formed. At this time, the first
Since the opening area of the diaphragm 70 is set smaller than the opening area of the second diaphragm 71, the pressure in the spring chamber 65 can be controlled to a value substantially equal to the pressure in the tank port Tl by appropriately designing the opening areas. On the other hand, the pressure in the oil passage 52 has a value close to 0 Bar during regeneration. For this reason, the check valve 54 is determined by the difference in hydraulic pressure acting on the pressure receiving area of the pressure receiving portion 66.
Can open and perform the regeneration function.

At the time of the regeneration, since the pressure receiving areas of the bottom side 11 and the rod side 12 of the hydraulic cylinder 10 are different, not all of the discharged oil amount from the bottom side 11 can be accommodated in the rod side 12. Excess flow rate occurs. Part of this surplus flow rate is also load port Ba → oil passage 52 → pressure receiving chamber 6
8 → hole 70 (first throttle) → spring chamber 65 → hole 71 (second throttle) → returned to the tank port Tl through the oil passage of the oil passage 53, and the rest was a load port Ba → a notch for meter-out flow rate control It is returned to the tank port Tl via 22d.

Further, when the pressure on the rod side of the boom cylinder 10 becomes high due to jack-up or the like at the time of regeneration, the check valve 56 closes, so that no trouble occurs.

Next, when the spool 22 is moved rightward in the figure by the boom raising operation, the oil passage 53 is closed by the land 5 or communicates with the load port Ba, and the spring chamber 65 is set to the same pressure as the load port Ba. Has become. On the other hand,
The pressure in the oil passage 51 is almost equal to the tank pressure (0 Bar). Therefore, as in the neutral state, the check valve 54 is kept closed, and the pressure oil in the load port Ba does not flow backward to the oil passage 51 side.

Next, the effects of the present embodiment will be described in comparison with the prior art.

As described above, when the directional control valve of the type shown in FIG. 7 (the directional control valve of the type shown in FIGS. 1 and 2 according to the present invention) is provided with a regeneration circuit as shown in FIG. In this case, the configuration is as shown by a dashed line, and in this case,
When raising the boom that has moved the spool 22B to the right in the figure,
A problem occurs in which a backflow from the high pressure side to the low pressure side occurs.

FIG. 7 shows a specific structure on the load port B side on the left side of the reproduction circuit shown by the two-dot chain line in FIG. 3.

In FIG. 3, the check valve 24 and the oil passage 31
The check valve 56 and the oil passage 5 shown on the right side of FIG.
Substantially the same as 5. The oil passage 30 is connected to the spool 22
The spool 22B is formed on the spool 22B so as to be closed by the land 4 at the time of neutralization of B and open to the load port Ba when the spool 22B moves to the left in the drawing (during regeneration).

Here, when the oil passage 30 and the load port Ba communicate with each other when the boom is lowered by moving the spool 22B to the left in the figure, the load port Ba → the oil passage 30 → the oil passage 32 → the check valve 25 (FIG. 7). → Oil passage 33 (Fig. 7) → Load port A
a (FIG. 7) and the pressure oil flows, and the return oil from the bottom side 11 of the hydraulic cylinder 10 is regenerated to the rod side 12. Also,
The surplus flow rate at the time of this regeneration is partly due to the oil passages 30, 32, the seat portion 161 in which the check valve 24 is in contact, and the pressure receiving chamber 168.
Is returned to the tank port Tl through the oil passage 31, and the remainder is returned from the load port Ba to the tank port Tl via the notch 22d for meter-out flow rate control. At this time, the flow at the check valve 24 is
This is a so-called outward flow that flows from the side to the pressure receiving chamber 168 via the sheet portion 161.

On the other hand, in FIG. 3, when the spool 22B is moved rightward by the boom raising operation, the oil passage 30 provided in the spool 33B communicates with the feeder port Ppl.
Feeder port Ppl → oil passage 30 → oil passage 32 → check valve 25 (FIG. 7) → oil passage 33 (FIG. 7) → tank port T
and high-pressure oil flows, and the oil discharged from the hydraulic pump 20 supplied to the feeder port Ppl escapes to the tank. For this reason, pressure oil cannot be supplied to the bottom side of the boom cylinder 10, and the boom cannot be raised. At this time, it is clear that the check valve 24 does not perform any function.

Therefore, the present invention provides a check valve 5 for inward flow between the load port Ba and the oil passage 51 in the spool 22.
4, the check valve 54 is opened when the boom is lowered to move the spool 22 to the left in the drawing, and the open / close control is performed so that the check valve 54 is closed when the spool 22 is operated in the reverse direction. . The fundamental difference between the check valve 24 shown in FIG. 3 and the check valve 54 of the present invention is that the connection between the oil passage 32 (51) provided in the spool 22B (22) and the load port Ba is the former. In this case, the opening and closing are performed through the oil passage 30 controlled to open and close in the land portion 4, whereas in the latter (the present invention)
Oil passage 52 and check valve 54 which open directly to load port Ba
Is performed by the control of

With this configuration, as described above, the directional control valve 21 is connected to the notches 22b,
Even if the spool 22d is open to the load port Ba, the regeneration function can be performed when the spool 22 is moved to the left in the figure, and the backflow of the pressure oil does not occur when the spool 22 is moved to the right in the figure. Moreover, the configuration changes the conventional check valve from the outward flow to the inward flow,
Only adding 0, 71 is very simple.

Further, in a multiple valve having a spool type in which a notch for flow control is opened to a load port, the size of a land is changed only for a directional control valve for providing a regeneration function.
There is no need to change the spool type, and the regeneration function can be easily added, and the piping connection work becomes complicated,
There is no risk of confusion in service and inspection.

[0066]

According to the present invention, even if the notch for controlling the amount is of a spool type opened to the load port, the regenerating function can be performed by one-way operation of the spool, and the reverse flow of the pressure oil by the opposite operation of the spool. Will not occur.

Further, in a multiple valve having a spool type in which a notch for controlling a flow rate is opened to a load port, the size of a land is changed only for a directional control valve for providing a regeneration function.
There is no need to change the spool type, and the regeneration function can be easily added, and the piping connection work becomes complicated,
There is no risk of confusion in service and inspection.

Further, the second check valve is very simple because it changes a conventional check valve from an outward flow to an inward flow and only adds holes such as a first throttle and a second throttle.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a directional control valve having a regeneration circuit according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a detailed structure of left and right check valves incorporated in a spool of the direction control valve shown in FIG.

FIG. 3 is a sectional view showing a detailed structure of a conventional check valve.

FIG. 4 is a diagram illustrating the appearance of a hydraulic excavator and a surface compaction operation as an example of an operation in which a negative load is applied.

FIG. 5 is a cross-sectional view of a closed center type directional control valve having a conventional regeneration circuit.

FIG. 6 is a cross-sectional view of an open center type directional control valve having a conventional regeneration circuit.

FIG. 7 is a sectional view of another conventional open center type directional control valve.

[Explanation of symbols]

 P Pump port Pb Center bypass port Pbr Right, left center bypass port Pp Parallel port Ppr, Ppl right, left feeder port A, Aa Right load port B, Ba Left load port Tr, Tl Right, left tank port 1, 2, 3 , 4, 5, 6 Land 7 Large spool diameter portion 8, 8B Small spool diameter portion 10 Boom cylinder 11 Bottom side 12 Rod side 15 Remote control valve 16 Anti-drift valve 20 Hydraulic pump 21 Directional control valve 21a Valve body 22 Spool 22a, 22b , 22c, 22d notch 23 hold check valve 50 regeneration circuit 51 oil passage (first oil passage) 52 oil passage (second oil passage) 53 oil passage (third oil passage) 54 check valve (second check valve 55) Oil passage 56 Check valve (first check valve) 60 Valve body 61 Seat 6 Spring 64 Cylindrical guide part 65 Spring chamber 66, 67 Pressure receiving part 68 Pressure receiving chamber 70 Hole (first throttle) 71 Hole (second throttle) 80 Valve body 81 Seat part 82 Spring 84 Cylindrical guide part 85 Spring chamber 86, 87 Pressure receiving section 88 Pressure receiving chamber 90 holes

 ──────────────────────────────────────────────────の Continuing on the front page (72) Kinya Takahashi, Inventor Kinyacho, Tsuchiura-shi, Ibaraki Pref.Hitachi Construction Machinery Co., Ltd. F-term in Tsuchiura Plant (reference) 3H089 AA55 AA69 BB04 BB12 CC03 DB13 DB32 DB33 HH05 JJ02

Claims (3)

[Claims] 1. A regeneration circuit for returning return oil from a return load port to a supply load port via a first oil passage and a first check valve provided in the spool when the spool is operated in one direction. A directional control valve, wherein a second check valve for inward flow is disposed between the return load port and the first oil passage within the spool, and the second check is performed during one-way operation of the spool. A directional control valve having a regeneration circuit, comprising: an opening and closing control means for opening a valve and closing the second check valve when the spool is operated in a reverse direction. 2. The directional control valve having a regeneration circuit according to claim 1, wherein a second oil passage that opens directly to the return load port is provided on the spool, and the second check valve is the second oil passage. And a valve body for controlling the opening and closing of the first oil passage. The opening / closing control means is provided on a valve body of the second check valve, and connects the second oil passage with a spring inside the valve body. A first throttle that communicates with the chamber; and a second throttle that is provided on the valve body of the check valve and that communicates the spring chamber with the tank port when the spool is operated in one direction. A directional control valve having a regeneration circuit, wherein the area is smaller than the opening area of the second throttle. 3. The directional control valve having a regeneration circuit according to claim 2, wherein said opening / closing control means further includes a third oil passage formed in said spool and opening to said tank port when operating said spool in one direction. A directional control valve having a regeneration circuit, wherein the second throttle is open to the third oil passage.