KR20190035813A - Hydraulic control valve and hydraulic control circuit - Google Patents

Abstract

A hydraulic control valve and a hydraulic control circuit are provided so that the pressure loss of the return oil at the time of contraction operation of the hydraulic cylinder can be reduced without the quick return circuit being provided outside and the cost can be reduced and the fuel consumption can be improved do. The hydraulic control valve of one embodiment has a valve body for controlling the pressure drop across the hydraulic cylinder. The valve body has a main tank passage and a sub tank passage. The main tank passage is connected to the tank through back pressure maintenance means. The sub tank passages are directly connected to the tank without passing through the back pressure maintenance means. In the state where the hydraulic cylinder is switched to the position for operating the shrinkage side, the head side power supply passage through which the return oil from the head side oil chamber of the hydraulic cylinder flows is communicated with both the main tank passage and the sub tank passage .

Description

Hydraulic control valve and hydraulic control circuit

An embodiment of the present invention relates to a hydraulic control valve and a hydraulic control circuit.

[0003] A hydraulic excavator, which is a type of construction machine, is a work attachment, and includes a boom, an arm, and a bucket that are operated by hydraulic cylinders. The hydraulic control circuit (hydraulic cylinder circuit) for driving the respective hydraulic cylinders controls both the extension and retraction side oil chambers (head side oil chamber and rod side oil chamber) of the hydraulic pump and the tank and the hydraulic cylinder to control valves Valve). And, by the control valve, control of the pressure drop across the hydraulic cylinder, that is, the expansion and contraction operation of the cylinder.

In the hydraulic cylinder, the hydraulic pressure area against the head side oil chamber of the piston is larger than the hydraulic pressure area against the rod side oil chamber by the cross sectional area of the piston rod. Therefore, in the cylinder shrinking operation (in the operation of supplying the pressurized oil to the rod-side oil chamber and discharging the pressurized oil from the head-side oil chamber) due to the hydraulic pressure difference between the head side oil chamber and the rod side oil chamber, There is a possibility that the flow rate of the return oil in the oil chamber is larger than the flow rate of the pressure oil supplied to the rod side oil chamber. In this case, the pressure loss of the return oil is increased, the operating speed of the hydraulic cylinder is lowered, and further, the improvement of the fuel economy of the hydraulic excavator is hindered.

As a countermeasure against this problem, a quick return circuit communicating with the tank is branched and connected to the head side pipeline of the hydraulic cylinder, and part of the return oil from the head side oil chamber of the hydraulic cylinder is directly returned to the tank at the time of cylinder shrinking operation, And the pressure loss of the return oil is reduced (see Patent Document 1). However, when a quick return circuit is provided, it is necessary to newly install a hydraulic piping or a quick return valve, which may increase the cost.

Japanese Patent Application Laid-Open No. 2013-137062

A problem to be solved by the present invention is to reduce the pressure loss of return oil at the time of contraction operation of a hydraulic cylinder without providing a quick return circuit on the outside, thereby reducing costs and improving fuel economy And an oil pressure control circuit including the oil pressure control valve.

The hydraulic control valve of the embodiment has a valve body that is connected between the hydraulic cylinder and the hydraulic pump and the tank and that performs a switching operation to control the pressure drop across the hydraulic cylinder. The valve body has a main tank passage and a sub tank passage. The main tank passage is connected to the head side power supply passage connected to the head side oil chamber of the hydraulic cylinder and the tank through back pressure maintenance means. The sub tank passages are directly connected to the tank without passing through the back pressure maintenance means. In the state where the hydraulic cylinder is switched to the position for operating the shrinkage side, the head side power supply passage through which the return oil from the head side oil chamber of the hydraulic cylinder flows is communicated with both the main tank passage and the sub tank passage .

1 is a sectional view of a hydraulic control valve according to a first embodiment.
2 is a configuration diagram of the hydraulic control circuit of the first embodiment.
3 is a sectional view of the hydraulic control valve of the second embodiment.
4 is a configuration diagram of the hydraulic control circuit of the second embodiment.
5 is a schematic configuration diagram of a hydraulic excavator according to an embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a hydraulic control valve and hydraulic control circuit including the hydraulic control valve of the embodiment will be described with reference to the drawings.

The hydraulic control valve and the hydraulic control circuit of the embodiments described below are mainly used in a construction machine. First, an example of an applied construction machine will be described first. Fig. 5 shows a schematic configuration of a typical hydraulic excavator as a construction machine.

5, in the hydraulic excavator 300, a vehicle body body 305 and an upper swivel (not shown) are mounted on a lower traveling body 301 driven by a hydraulic motor through a swivel mechanism 302 having a swiveling motor. Body 303 is pivotally mounted. A cap 304 is provided in the upper revolving structure 303, and a work attachment is mounted in front of the cap 304. [

As the work attachment, a boom 311 is provided at the front central portion of the cap 304. [ An arm 312 is vertically rotatably provided at the tip of the boom 311. A bucket 313 is vertically rotatably provided at the tip of the arm 312. Here, reference numeral 314 denotes a hydraulic cylinder for raising and lowering the boom 311. Reference numeral 315 denotes a hydraulic cylinder for pushing and pulling the arm 312 (movement in a direction away from the upper revolving structure 303 and in a direction close to the upper revolving structure 303). Reference numeral 316 denotes a hydraulic cylinder for excavating and dumping the bucket 313.

(First Embodiment)

Fig. 1 is a sectional view of the hydraulic control valve of the first embodiment, and Fig. 2 is a configuration diagram of the hydraulic control circuit. In the first embodiment, the hydraulic control circuit of the hydraulic cylinder 316 for the bucket 313 shown in Fig. 5 is taken as an example.

The hydraulic control circuit includes a hydraulic cylinder 1 (hydraulic cylinder 316) for moving a load (bucket 313), a hydraulic control valve 10, a hydraulic pump 3, and a tank T .

The hydraulic cylinder 1 is provided with two working oil chambers of a rod side oil chamber 1A formed by the piston 1P and a head side oil chamber (oil opposite side oil chamber) 1B. A rod connected to the piston 1P is passed through the rod-side oil chamber 1A. Therefore, the hydraulic pressure area of the piston 1P with respect to the rod-side oil chamber 1A is smaller by the cross-sectional area of the rod than the hydraulic pressure area of the piston 1P with respect to the head-side oil chamber 1B. In the hydraulic cylinder 1, when pressurized oil is supplied to the rod-side oil chamber 1A, return oil from the head-side oil chamber 1B is generated and the entire length is contracted. On the other hand, when pressurized oil is supplied to the head side oil chamber 1B, return oil from the rod side oil chamber 1A is generated, and the hydraulic cylinder 1 is extended in its entire length.

Therefore, when the hydraulic cylinder 1 is contracted by the above-described hydraulic pressure area difference, the discharge amount of the return oil from the head side oil chamber 1B is smaller than the supply amount of the pressure oil to the rod side oil chamber 1A More. And the countermeasure is included in the hydraulic control valve 10. [

The hydraulic pressure control valve 10 controls the pressure drop across the hydraulic cylinder 1. The hydraulic control valve 10 is configured to be able to be positioned at three positions of a neutral position N, an A position (first position) and a B position (second position). 1, the hydraulic control valve 10 includes a valve body 11 having a sleeve hole 40 formed so as to pass along the axial direction of the valve body 11, Directional valve. The hydraulic control valve 10 is driven by the pilot pressures PA and PB.

The valve body 11 of the hydraulic control valve 10 is provided with a rod side power supply port 12A and a head side power supply port 12B which are disposed on both sides with the axial center in between. Here, in Fig. 1, the flow path on the rod side is formed on the left side from the axial center, and the flow path on the head side is formed on the right side from the axial direction center. The rod side power supply port 12A is connected to the rod side oil chamber 1A of the hydraulic cylinder 1 through the rod side power supply line 2A and the head side power supply port 12B is connected to the head side power supply line 2B To the head-side oil chamber 1B of the hydraulic cylinder 1. The oil-

A pump passage (13) disposed at the axial center is provided around the sleeve hole (40) of the valve body (11). The pump passage 13 is connected to the discharge port of the hydraulic pump 3. On both sides of the pump passage 13, first tank passages 14A and 14B are provided. On both outer sides of the first tank passages 14A and 14B, a rod-side bridge passage 15A and a head-side bridge passage 15B are provided. The rod-side power supply passage 16A connected to the rod-side power supply port 12A and the head-side power supply passage 16A connected to the head-side power supply port 12B are respectively provided at both outer sides of the rod side bridge passage 15A and the head side bridge passage 15B. Side supply passage 16B.

1, the main tank passage 17A as the second tank passage is provided on the outer side of the rod-side power supply passage 16A. The load side bridge passage 15A is connected to the pump passage 13 through the load check valve 20. [ The main tank passage 17A and the first tank passage 14A are connected to the tank T via a back pressure check valve 5. [

Next, the head side of the right side of FIG. 1 will be described. A sub tank passage 19 as a third tank passage is provided outside the head side power supply passage 16B. On the outside of the sub-tank passage 19, there is provided a branch acute supply passage 18 branch-connected to the head side acute passage 16B. A main tank passage 17B as a second tank passage is provided on the outside of the branch supply passage 18. The head side bridge passage 15B is connected to the pump passage 13 through the load check valve 20. [ The main tank passage 17B and the first tank passage 14B are connected to the tank T via a back pressure check valve (back pressure maintaining means) On the other hand, the sub tank passage 19 is directly connected to the tank T without passing through the back pressure check valve.

The rod side power supply passage 16A and the head side power supply passage 16B are connected to the main tank passages 17A and 17B through relief valves 21A and 21B for discharging excessive high pressure.

The spool 50 is provided with an A position pilot pressure surface 50A for switching the position of the spool 50 from the neutral position N to the A position on both end faces in the axial direction, And a pilot hydraulic pressure surface 50B for the B position for switching from the neutral position N to the B position. The spool (50) has a central land portion (51) at a central position in the axial direction. First annular recesses 52A and 52B are formed on both outer sides of the central land portion 51. [ Further, first land portions 53A and 53B are provided on both outer sides of the first annular concave portions 52A and 52B. Second annular recesses 54A and 54B are formed on both outer sides of the first land portions 53A and 53B. In addition, second land portions 57A and 57B are provided on both outer sides of the second annular concave portions 54A and 54B.

Particularly in the head side, the spool 50 has a third land portion 55B and an annular concave portion 56B between the second annular concave portion 54B and the second land portion 57B . The land portions and the annular concave portions are formed alternately arranged in the axial direction.

A first notch 61 is formed on the outermost periphery of the center side edge in the outermost second land portions 57A and 57B. The third land portion 55B on the head side is provided with a second notch 62 on the outer periphery of the center side edge. In addition, a third notch 63 is formed in the first land portions 53A and 53B on the outer periphery of the opposite side edge of the center. A fourth notch 64 is formed on the outer periphery of both edges of the central land portion 51.

Pilot ports Pa and Pb are provided in the hydraulic control valve 10 so as to face both ends of the spool 50. [ One of the two pilot ports Pa and Pb is a port for inputting a pilot pressure PA for switching the spool 50 to the A position. The pilot port Pa is disposed at the end of the positioning mechanism 70 provided in the valve body 11. [ The other pilot port Pb is a port for inputting the pilot pressure PB for switching the spool 50 to the B position. The pilot port Pb is disposed on the side where the positioning mechanism 70 is not provided. The operating mechanism (direction switching mechanism) of the spool 50 is constituted by two pilot ports Pa and Pb and a positioning mechanism 70. [

The positioning mechanism 70 is disposed on one side of the valve body 11 and has a cap-shaped casing 71 whose one end is opened. The casing 71 is fixed to one side surface of the valve body 11 so as to close one end of the sleeve hole 40 of the valve body 11. Inside the casing 71, a spring accommodation chamber 71a accommodating a coil spring 77 is provided. A pilot port Pa is formed in the end wall 71d of the small diameter hole portion 71b at an end of the spring accommodation chamber 71a through a stopper wall 71c. .

A rod 72 is integrally fixed to the end of the spool 50 on the positioning mechanism 70 side. The rod 72 is inserted into the casing 71 and a head portion 73 having an outer peripheral flange faces the pilot port Pa. A first spring bearing sleeve 74 and a second spring bearing sleeve 75 are provided on the outer periphery of the rod 72 so as to be axially slidable. The first spring bearing sleeve 74 and the second spring bearing sleeve 75 are formed as opposed end portions as the impact end portions 74b and 75b. Flange portions 74a and 75a for receiving a spring force are provided at opposite ends of the first spring bearing sleeve 74 and the second spring bearing sleeve 75, respectively.

The coil spring 77 that presses the spool 50 toward the neutral position is mounted on the outer periphery of the first spring bearing sleeve 74 and the second spring bearing sleeve 75. Both ends of the coil spring 77 are accommodated in both flange portions 74a and 75a of the first spring bearing sleeve 74 and the second spring bearing sleeve 75 in the compressed state.

The positioning mechanism 70 positions and holds the spool 50 at the neutral position N when the pilot pressures PA and PB are not introduced into the pilot ports Pa and Pb. That is, by the force of the coil spring 77, the first spring bearing sleeve 74 is urged to the left in FIG. 1 and the second spring bearing sleeve 75 is urged to the right in FIG. Thereby, the collision ends 74b and 75b of the first spring bearing sleeve 74 and the second spring bearing sleeve 75 are spaced from each other (not shown in Fig. 1). The flange portion 74a of the first spring bearing sleeve 74 abuts against the stopper wall 71c inside the casing 71 and the flange portion 75a of the second spring bearing sleeve 75 abuts on the valve body 11 The stopper wall 45 provided at the peripheral edge of the opening of the sleeve hole 40 of the cover 40 is brought into contact with the stopper wall 45. Thereby, the spool 50 fixed to the rod 72 is held at the neutral position N. [

The positioning mechanism 70 holds the spool 50 at the position A when the pilot pressure PA is introduced into the pilot port Pa. That is, when the pilot pressure PA is introduced into the pilot port Pa in the neutral position, the pilot pressure PA is applied to the end surface of the rod 72 and the A position pilot pressure receiving surface 50A of the spool 50 So that the spool 50 is pushed to the right side in the drawing. At this time, the coil spring 77 contracts, and the first spring bearing sleeve 74 moves to the right. The collision end 74b of the first spring bearing sleeve 74 then collides against the collision end 75b of the second spring bearing sleeve 75 and is held in position. Thereby, the spool 50 fixed to the rod 72 is held at the position A.

The positioning mechanism 70 holds the spool 50 at the position B when the pilot pressure PB is introduced into the pilot port Pb. That is, when the pilot pressure PB is introduced into the pilot port Pb in the neutral position, the pilot pressure PB acts on the B-position pilot pressure surface 50B of the spool 50, And is pushed to the left side in the drawing. At this time, the coil spring 77 contracts, and the second spring bearing sleeve 75 moves to the left. The collision end 75b of the second spring bearing sleeve 75 then collides against the collision end 74b of the first spring bearing sleeve 74 and is held in position. Thereby, the spool 50 fixed to the rod 72 is held at the position B.

Next, the operation of the hydraulic control valve 10 and the hydraulic control circuit will be described with reference to Figs. 1 and 2. Fig.

First, the case where the spool 50 is at the neutral position N will be described. In this case, the pump passage 13 communicates with the first tank passages 14A and 14B through the fourth notch 64 and the first annular recesses 52A and 52B. At this time, the rod-side bridge passage 15A, the head-side bridge passage 15B, the rod-side power supply passage 16A, and the head-side power supply passage 16B are kept closed.

Next, the case where the spool 50 is at the position A will be described. In this case, the communication between the pump passage 13 and the first tank passages 14A and 14B is cut off. Side bridge passage 15A and the rod-side power supply passage 16A are communicated with each other through the third notch 63 and the second annular concave portion 54A at the rod side (the pressurized oil supply side in the left side in Fig. 1) do. Thereby, the pressure oil that has flowed into the rod-side bridge passage 15A through the load check valve 20 flows into the rod-side power supply passage 16A through the third notch 63 and the second annular concave portion 54A ≪ / RTI > Then, the pressurized oil is introduced into the rod-side oil chamber 1A of the hydraulic cylinder 1 through the rod-side power supply port 12A and the rod-side power supply line 2A.

On the other hand, the head side bridge passage 15B is closed on the head side (the return oil return side on the right side in Fig. 1). The head side power supply passage 16B and the sub tank passage 19 communicate with each other through the second notch 62 and the second annular concave portion 54B. The branch acute supply passage 18 and the main tank passage 17B connected to the head side acute supply passage 16B communicate with each other through the first notch 61 and the annular concave portion 56B. The return oil from the head side oil chamber 1B of the hydraulic cylinder 1 is discharged to the tank T through both the main tank passage 17B and the sub tank passage 19. [

That is, the return oil passing through the main tank passage 17B is discharged to the tank T through the back pressure check valve 5. [ On the other hand, the return oil passing through the sub tank passage 19 is discharged directly to the tank T without passing through the back pressure check valve. Here, the back pressure check valve 5 is generally set such that the pressure (back pressure) of the pressure oil in the main tank passages 17A, 17B is about 0.3 to 0.5 MPa.

The hydraulic control valve 10 is switched to the A position when the bucket hydraulic cylinder 1 is contracted. When the bucket hydraulic cylinder 1 is contracted, the bucket 313 performs an extrusion operation (also referred to as a dump or opening operation).

Next, the case where the spool 50 is at the B position will be described. In this case, the communication between the pump passage 13 and the first tank passages 14A and 14B is cut off. The head side bridge passage 15B and the head side power supply passage 16B are communicated with each other through the third notch 63 and the second annular concave portion 54B at the head side (the pressurized oil supply side at the right side in Fig. 1) do. Thereby, the pressure oil flowing into the head side bridge passage 15B through the load check valve 20 flows into the head side power supply passage 16B through the third notch 63 and the second annular concave portion 54B ≪ / RTI > The compressed oil is then introduced into the head side oil chamber 1B of the hydraulic cylinder 1 through the head side power supply port 12B and the head side power supply line 2B.

On the other hand, at the rod side (the return oil return side from the left side in Fig. 1), the rod side bridge passage 15A is closed. The rod side supply passage 16A and the main tank passage 17A communicate with each other through the first notch 61 and the second annular concave portion 54A. Thereby, the return oil from the rod-side oil chamber 1A of the hydraulic cylinder 1 is discharged to the tank T through the main tank passage 17A. That is, the return oil passing through the main tank passage 17A is discharged to the tank T through the back pressure check valve 5. [

The hydraulic control valve 10 is switched to the B position when the bucket hydraulic cylinder 1 is extended. When the bucket hydraulic cylinder 1 is extended, the bucket 313 performs excavation (also referred to as closing operation).

As described above, in the hydraulic control valve 10, the sub tank passage 19 as the third tank passage is provided outside the head side power supply passage 16B provided in the valve body 11. Further, on the outside of the sub-tank passage 19, there is provided a branch acute supply passage 18 branch-connected to the head side acute passage 16B. Further, a main tank passage 17B as a second tank passage is provided outside the branch diaphragm passage 18. The head side bridge passage 15B is connected to the pump passage 13 through the load check valve 20. [ The main tank passage 17B and the first tank passage 14B are connected to the tank T via a back pressure check valve (back pressure maintaining means) On the other hand, the sub tank passage 19 is directly connected to the tank T without passing through the back pressure check valve.

The return oil from the head side oil chamber 1B is discharged to the tank T through both passages of the main tank passage 17B and the sub tank passage 19 at the time of contraction operation of the hydraulic cylinder 1 can do. Therefore, the pressure loss of the return oil can be reduced as compared with the case where the return oil is discharged to the tank T only through the main tank passage 17B. The sub tank passage 19 returns the return oil from the head side oil chamber 1B directly to the tank T without passing through the back pressure check valve 5 so that the pressure loss can be greatly reduced.

The return oil from the head side oil chamber 1B is branched into both the main tank passage 17B and the sub tank passage 19 and flows in the valve body 11. As compared with the case where a quick return circuit for quickly returning the return oil from the head side oil chamber 1B to the tank T is separately provided outside the hydraulic control valve 10, . In other words, the sub tank passage 19 for directly discharging the return oil to the tank T without passing through the back pressure check valve is provided in the valve body 11 of the hydraulic control valve 10 itself separately from the main tank passage 17B Is installed. Therefore, it is not necessary to provide the quick return circuit separately from the hydraulic control valve 10, and the circuit configuration can be simplified.

The return oil from the head side oil chamber 1B of the hydraulic cylinder 1 is returned to the main tank passage 1B only by switching the position of the spool 50 to the position of the shrinkage adjustment action A of the hydraulic cylinder 1. [ 17B to the tank T via the sub-tank passage 19, as shown in Fig. That is, the two tank passages (the main tank passage 17B and the sub tank passage 19) can be opened and closed by the switching operation of one spool 50. In this case, since the means for switching the opening and closing of the sub tank passage 19 are integrally provided on the spool 50, no separate operating means is required from the spool 50, It becomes easy. In other words, there is no need to provide a quick return valve for opening and closing the quick return circuit as in the prior art, so that the configuration can be simplified.

The head side power supply passage 16B (branch power supply passage 18) is communicated with the main tank passage 17B through the first notch 61 by the switching operation of the spool 50. [ In addition to this, the head side power supply passage 16B is communicated with the sub tank passage through the second notch 62. Thereby, the return oil from the head side oil chamber 1B of the hydraulic cylinder 1 is discharged to the tank T through the main tank passage 17B and the sub tank passage 19 by this operation. The first notch 61 and the second notch 62 in this case maintain their relative positions determined by machining. Therefore, the timing at which the head side power supply path 16B (branching power supply path 18) is in communication with the main tank path 17B and the timing at which the head side power supply path 16B is in communication with the sub tank path 19 There is no work.

(Second Embodiment)

Next, a second embodiment will be described based on Fig. 3 and Fig. Fig. 3 is a sectional view of the hydraulic control valve 100 in the second embodiment, and Fig. 4 is a configuration diagram of the hydraulic control circuit. In the second embodiment, the hydraulic control circuit of the hydraulic cylinder 315 for the arm 312 shown in Fig. 5 will be described as an example.

The hydraulic control circuit includes a hydraulic cylinder 1 (hydraulic cylinder 315) for moving a load (arm 312), a hydraulic control valve 100, two hydraulic pumps 103 and 203, (T). The oil hydraulic cylinder 1 (hydraulic cylinder 315) is generally moved by two hydraulic pumps 103 and 203, as shown in Figs. 3 and 4.

Here, the construction of the hydraulic cylinder 1 is the same as that of the first embodiment, but the structure of the hydraulic control valve 100 is different from that of the first embodiment, because two hydraulic pumps 103 and 203 are used. 3, two spools 150 and 250 are used to control the pressure control on the hydraulic cylinder 1 by two spools 150 and 250. In other words, ).

More specifically, the hydraulic control valve 100 controls the pressure drop across the hydraulic cylinder 1. The two spools 150 and 250 of the hydraulic control valve 100 are configured so as to be positioned at three positions of the neutral position N, the A position (first position) and the B position (second position) .

3, the hydraulic control valve 100 includes two sleeve holes 140, 240 formed in parallel to each other in the axial direction along the axial direction of the valve body 111, And 250 are inserted in an axially slidable manner. Each of the spools 150 and 250 is driven by pilot pressures PA and PB. The configuration of each flow path switched by the spools 150 and 250 and the spools 150 and 250 is basically the same as that of the first embodiment. In the same constituent parts as those of the first embodiment, A code of 100 in number obtained by adding 100 to the code in 2 digits in the embodiment and a code of 200 in number obtained by adding 200 are associated with the constituent parts of the first embodiment.

The valve body 111 of the hydraulic control valve 100 is provided with a rod side supply port 112A and a head side supply port 112B which are disposed on both sides with the center in the axial direction therebetween. Here, in Fig. 1, the flow path on the rod side is formed on the left side from the axial center, and the flow path on the head side is formed on the right side from the axial direction center. The rod side supply port 112A is connected to the rod side oil chamber 1A of the hydraulic cylinder 1 through the rod side supply line 2A. The head side power supply port 112B is connected to the head side oil chamber 1B of the hydraulic cylinder 1 through the head side power supply line 2B.

At the periphery of the sleeve holes 140 and 240 of the valve body 111, there are provided pump passages 113 and 213 disposed at the axial center. The pump passages 113 and 213 are connected to the discharge ports of the hydraulic pumps 103 and 203, respectively. First tank passages 114A, 114B, 214A and 214B are provided on both outer sides of the pump passages 113 and 213, respectively. Side bridge passages 115A and 215A and head-side bridge passages 115B and 215B are provided on both outer sides of the first tank passages 114A, 114B, 214A and 214B. The rod-side power supply passages 116A and 216A which are both communicated with the rod-side power supply port 112A are provided on both outer sides of the rod-side bridge passages 115A and 215A and the head-side bridge passages 115B and 215B, Side power feeding passages 116B and 216B which are all communicated with the power feeding passages 112B.

3, main tank passages 117A and 217A as second tank passages are provided on the outside of the rod-side power supply passages 116A and 216A. The rod side bridge passages 115A and 215A are connected to the pump passages 113 and 213 through the load check valves 120 and 220, respectively. The main tank passages 117A and 217A and the first tank passages 114A and 214A are connected to the tank T via a back pressure check valve (back pressure maintaining means)

3, sub tank passages 119 and 219 as third tank passages are provided outside the head side power supply passages 116B and 216B. Outside the sub tank passages 119 and 219, there are provided branch diaphragm passages 118 and 218 communicating with each other. These branch acute supply passages 118 and 218 are connected to the head side acute supply passages 116B and 216B through a pilot check valve 280 to be described later.

Main tank passages 117B and 217B as second tank passages are provided outside the branch acute feeding passages 118 and 218. [ The head side bridge passages 115B and 215B are connected to the pump passages 113 and 213 via the load check valves 120 and 220, respectively. The main tank passages 117B and 217B and the first tank passages 114B and 214B are connected to the tank T via a back pressure check valve (back pressure maintaining means) On the other hand, the sub tank passages 119 and 219 are directly connected to the tank T without passing through the back pressure check valve.

The rod side power supply path 116A and the head side power supply path 116B are connected to the main tank paths 117A and 117B through relief valves 121A and 121B which discharge excessively high pressure.

The spools 150 and 250 are provided on both end faces in the axial direction with pilot pressure surfaces 150A and 250A for A position for switching the positions of the spools 150 and 250 to the A position, Position pilot pressure surfaces 150B and 250B for switching the position to the B position.

The configuration on the outer circumferential side of the spools 150 and 250 is the same as that of the first embodiment as indicated by corresponding reference numerals to the first embodiment (see Fig. 1). That is, the spools 150 and 250 have the central land portion 51 at the central position in the axial direction, and have the first annular recesses 52A and 52B on both outer sides of the central land portion 51. The first land portions 53A and 53B are provided on both outer sides of the first annular concave portions 52A and 52B and the second annular concave portions 53A and 53B are formed on both outer sides of the first land portions 53A and 53B 54A, and 54B are formed. Second land portions 57A and 57B are provided on both outer sides of the second annular concave portions 54A and 54B. The spools 150 and 250 on the head side also have a third land portion 55B and an annular concave portion 56B between the second annular concave portion 54B and the second land portion 57B . These land portions and annular concave portions are formed alternately arranged in the axial direction.

A first notch 61 is formed on the outer periphery of the center side edge of the outermost second land portions 57A and 57B. A second notch 62 is formed on the outer periphery of the center side edge of the third land portion 55B on the head side. A third notch 63 is formed on the outer periphery of the opposite side edge of the first land portions 53A and 53B. A fourth notch 64 is formed on the outer periphery of both edges of the central land portion 51.

In the hydraulic control valve 100, pilot ports Pa and Pb are provided so as to face both ends of the spools 150 and 250, respectively. The pilot port Pa on one side of the two pilot ports Pa and Pb is a port for inputting the pilot pressure PA for switching the spools 150 and 250 to the A position. The pilot port Pa is disposed at the end of the positioning mechanism 70 provided in the valve body 111. [

The other pilot port Pb is a port for inputting a pilot pressure PB for switching the spools 150 and 250 to the B position. The pilot port Pb is disposed on the side where the positioning mechanism is not provided. The operating mechanism (direction switching mechanism) of the spools 150 and 250 is composed of two pilot ports Pa and Pb and a positioning mechanism 70. The positioning mechanism 70 has the same configuration as that of the first embodiment, and a detailed description thereof will be omitted.

Next, the pilot check valve 280 and the regeneration passage for introducing a part of the return oil to the pressure oil supply side will be described.

A pilot check valve 280 is provided between the head side power source passage 216B and the branch acute power source passage 218 as described above. This pilot check valve 280 cuts off the communication between the head side acute supply passage 216B and the branch acute passage passage 218 when no pilot signal is inputted. The pilot check valve 280 performs a check function to prevent the pressure oil flowing into the head side power supply passage 216B from flowing to the branch steam supply passage 218 side downstream of the head side power supply passage 216B. The pilot check valve 280 permits communication between the head side power supply path 216B and the branch power supply path 218 when a pilot signal is input.

The pilot check valve 280 includes a poppet-shaped main valve body 281 for opening and closing the flow path between the head side power supply path 216B and the branching acute supply path 218, And a pilot mechanism section 285 for controlling the pilot mechanism section 285. The main valve body 281 is inserted into the valve body receiving hole formed in the valve body 111 so as to be slidable in the valve opening / closing direction. A back pressure chamber 281a is provided in the main valve body 281. The back pressure chamber 281a communicates with the head side power supply passage 216B on the upstream side through the pores 281b.

The pilot mechanism portion 285 has a casing 285a mounted so as to cover the valve body receiving hole of the main valve body 281. [ A slide hole 285b is formed in the casing 285a. A sub valve element 286 is slidably inserted into the slide hole 285b. The sub valve body 286 is connected to the piston 287 so that when the pilot pressure acts on the piston 287, the sub valve body 286 moves to the open side. Small-diameter flow passages 288a, 288b, 288c, and 288d are provided in a portion of the valve body 111 provided with the casing 285a and the casing 285a.

Under such a configuration, when the pilot pressure acts on the pressure receiving surface of the piston 287, the piston 287 moves and the sub-valve body 286 connected to the piston 287 moves. The pressurized fluid flowing into the back pressure chamber 281a of the main valve body 281 flows to the downstream side of the main valve body 281 through the small-diameter flow passages 288a, 288b, 288c, and 288d. The pressure difference between the back pressure chamber 281a and the outside of the main valve body 281 is eliminated, so that the main valve body 281 moves to the open position. Thereby, the return oil flows from the upstream side head side power supply passage 216B to the downstream side branch gas supply passage 218.

When the return oil flows to the branch supply passage 218, the return oil flows also to the branch supply passage 118 communicating with the branch supply passage 218. When both of the spools 150 and 250 are in the A position, both the branch supply and discharge passages 118 and 218 communicate with the main tank passages 117B and 217B through the first notch 61. [ The return oil flowing into the branch acute supply passages 118 and 218 flows to the main tank passages 117B and 217B via the first notch 61 and is discharged to the tank T through the back pressure check valve 5 do.

A part of the return oil that has flowed into the branch acute supply passages 118 and 218 is introduced to the pressure oil supply path to the rod side oil chamber 1A of the hydraulic cylinder 1 in accordance with the pressure level. This passage is called a regeneration passage. The regeneration passage includes a head side radial hole 254 formed in the peripheral wall at the head side position of the spool 250, an axial passage 255 formed in the spool 250, A rod side radial hole 256 formed in the peripheral wall at the position on the rod side and a check valve 260 inserted into a predetermined portion of the axial passage 255.

The head side radial hole 254 is disposed at a position to communicate with the branch acute passage 218 when the spool 250 is positioned at the A position. The rod-side radial hole 256 is disposed at a position where it communicates with the rod-side power supply passage 216A when the spool 250 is positioned at the A position. The check valve 260 is arranged to open and close the head side radial hole 254 and is set to open when the pressure of the head side power supply passage 216B is higher than the pressure of the rod side power supply passage 216A have.

Next, the operation of the hydraulic control valve 100 and the hydraulic control circuit will be described with reference to Figs. 3 and 4. Fig.

First, the case where the spools 150 and 250 are at the neutral position N will be described. In this case, the pump passages 113 and 213 communicate with the first tank passages 114A, 114B, 214A, and 214B through the fourth notch 64 and the first annular recesses 52A and 52B. At this time, the rod side bridge passages 115A and 215A, the head side bridge passages 115B and 215B, the rod side power feeding passages 116A and 216A, and the head side power feeding passages 116B and 216B are kept closed.

The switching operation of the two spools 150 and 250 is performed in synchronization. That is, the pilot pressure PA or the pilot pressure PB is simultaneously introduced to the two spools 150 and 250. A pilot pressure PA for moving the spools 150 and 250 to the position A is introduced to the pilot port of the pilot check valve 280 as a pilot pressure.

Next, the case where the spools 150 and 25 are at the A position will be described. In this case, the communication between the pump passages 113, 213 and the first tank passages 114A, 114B, 214A, 214B is cut off. The rod-side bridge passages 115A and 215A and the rod-side power supply passages 116A and 216A are connected to the third notch 63 and the second annular concave portion 54A . As a result, the respective pressures from the hydraulic pumps 103 and 203 flowing through the rod check valves 120 and 220 and flowing into the rod side bridge passages 115A and 215A are controlled by the third notch 63 and the second annular phase, Side air supply passages 116A and 216A through the concave portion 54A. The compressed oil is introduced into the rod side oil chamber 1A of the hydraulic cylinder 1 through the rod side supply port 112A and the rod side supply side line 2A.

On the other hand, the head side bridge passages 115B and 215B are closed at the head side (the return oil return side from the right side in Fig. 3). The head side power supply passages 116B and 216A and the sub tank passages 119 and 219 communicate with each other through the second notch 62 and the second annular concave portion 54B. Further, the pilot check valve 280 is operated to be disposed at the open position, whereby the return oil introduced into the head side acute supply passages 116B and 216B is introduced into the branch acute supply passages 118 and 218. At this time, since the spools 150 and 250 are at the A position, the branch acute supply passages 118 and 218 and the main tank passages 117B and 217B communicate with each other through the first notch 61. [

The return oil from the head side oil chamber 1B of the hydraulic cylinder 1 is discharged to the tank T through both the main tank passages 117B and 217B and the sub tank passages 119 and 219 . That is, the return oil passing through the main tank passages 117B and 217B is discharged to the tank T through the back pressure check valve 5. [ The return oil passing through the sub tank passages 119 and 219 is directly discharged to the tank T without passing through the back pressure check valve. Here, the back pressure check valve 5 is generally set such that the pressure (back pressure) of the pressure of the main tank passages 117A, 117B, 217A, 217B is about 0.3 to 0.5 MPa.

The switching of the hydraulic control valve 100 to the position A is for operating the hydraulic cylinder 1 (hydraulic cylinder 315) for shrinking. When the female hydraulic cylinder 1 (hydraulic cylinder 315) is contracted, the arm 312 performs an extruding operation.

Next, the case where the spools 150 and 250 are at the B position will be described. In this case, the communication between the pump passages 113, 213 and the first tank passages 114A, 114B, 214A, 214B is cut off. The head side bridge passages 115B and 215B and the head side power supply passages 116B and 216B are connected to the third notch 63 and the second annular concave portion 54B . Thereby, the pressure oil that has flowed into the head side bridge passages 115B and 215B through the load check valves 120 and 220 flows through the third notch 63 and the second annular concave portion 54B, (116B, 216B). The compressed oil is introduced into the head side oil chamber 1B of the hydraulic cylinder 1 through the head side power supply port 112B and the head side power supply line 2B.

On the other hand, at the rod side (the return oil return side from the left side in Fig. 3), the rod side bridge passages 115A and 215A are closed. The rod side supply passages 116A and 216A and the main tank passages 117A and 217A communicate with each other through the first notch 61 and the second annular concave portion 54A. The return oil from the rod side oil chamber 1A of the hydraulic cylinder 1 is discharged to the tank T through the main tank passages 117A and 217A. That is, the return oil passing through the main tank passages 117A and 217A is discharged to the tank T through the back pressure check valve 5. [

The switching of the hydraulic control valve 10 to the B position is for extending the hydraulic cylinder 1 (hydraulic cylinder 315) for the arm. When the female hydraulic cylinder 1 (hydraulic cylinder 315) is extended, the arm 312 performs a pulling operation.

For example, as shown in Fig. 5, when the arm 315 is extruded from the folded state, the female hydraulic cylinder 315 is operated to contract. At this time, due to the weight of the arm 312 or the bucket 313, a large inertial force acts on the hydraulic cylinder 1 toward the shrinkage side. In this case, the supply of the pressure oil to the rod-side oil chamber 1A of the hydraulic cylinder 1 is not followed and cavitation may occur.

At this time, the regeneration passage functions. That is, at this time, since the pressure of the return oil from the head side oil chamber 1B is high, the returning oil introduced from the head side oil supplying passages 116B and 216B through the pilot check valve 280 to the branch oil path 218 The oil opens the check valve 260 of the regeneration passage and joins the pressure of the rod-side power supply passages 116A and 216A. Thereby, a sufficient oil amount can be supplied to the rod-side oil chamber 1A of the hydraulic cylinder 1 while preventing cavitation.

As described above, in the hydraulic control valve 100 and the hydraulic control circuit, the return oil from the head side oil chamber 1B is supplied to the main tank passages 117B and 217B and the sub- And can be discharged to the tank T through the passages on both sides of the passages 119 and 219. Therefore, the pressure loss of the return oil can be reduced as compared with the case where the return oil is discharged to the tank T through only the main tank passages 117B and 217B. The sub tank passages 119 and 219 return the return oil from the head side oil chamber 1B directly to the tank T without passing through the back pressure check valve 5 so that the pressure loss can be greatly reduced .

The return oil from the head side oil chamber 1B is branched and flowed into both the main tank passages 117B and 217B and the sub tank passages 119 and 219 within the valve body 111. [ Therefore, compared with the case where the quick return circuit for quickly returning the return oil from the head side oil chamber 1B to the tank T is separately provided outside the hydraulic control valve 100, the circuit configuration can be simplified have. In other words, the valve body 111 of the hydraulic control valve 100 is provided with a sub-tank passage 119 for discharging the return oil directly to the tank T without passing through the back pressure check valve, separately from the main tank passages 117B and 217B , 219) are installed. Therefore, it is not necessary to provide the quick return circuit separately from the hydraulic control valve 100, and the circuit configuration can be simplified.

The return oil from the head side oil chamber 1B of the hydraulic cylinder 1 is returned to the main oil chamber 1B only by switching the position of the two spools 150, Can be returned to the tank T through the sub tank passages 119 and 219 in addition to returning to the tank T through the tank passages 117B and 217B. That is, two sets of two tank passages (the main tank passages 117B and 217B and the sub tank passages 119 and 219) can be opened and closed by the switching operation of the spools 150 and 250. In this case, since means for switching the opening and closing of the sub tank passages 119 and 219 are integrally provided on the spools 150 and 250, no separate operating means is required from the spools 150 and 250, The opening and closing control of the valve can be easily performed. In other words, there is no need to provide a quick return valve for opening and closing the quick return circuit as in the prior art, so that the configuration can be simplified.

The branch dispensers 118 and 218 are communicated with the main tank passages 117B and 217B through the first notch 61 by the switching operation of the spools 150 and 250. [ In addition to this, the head side power supply passages 116B and 216B are communicated with the sub tank passages 119 and 219 through the second notch 62. Thereby, the return oil from the head side oil chamber 1B of the hydraulic cylinder 1 is discharged to the tank T through the main tank passages 117B and 217B and the sub tank passages 119 and 219. In this case, the first notch 61 and the second notch 62 maintain relative positions determined by machining. Therefore, the timing at which the branch acute supply passages 118 and 218 communicate with the main tank passages 117B and 217B and the timing at which the head side acute supply passages 116B and 216B communicate with the sub tank passages 119 and 219 There is no.

When the pilot signal is input to the pilot check valve 280, the return oil flowing into the head side power supply passages 116B and 216B flows through the first notch 61 and the second notch 62, Tank passages 117B and 217B and sub-tank passages 119 and 219, respectively. That is, in a state in which the pilot signal is not inputted to the pilot check valve 280, the flow of the pressure oil discharged into the tank T through the first notch 61 and the main tank passages 117B and 217B is restricted . Thereby, the supporting force of the hydraulic cylinder 1 against the external force can be maintained.

For example, as in the second embodiment, if there are four notches 61, 61, 62 and 62 in total in the two spools 150 and 250, the tank T, which has passed through the spools 150 and 250, There is a possibility that the bearing force of the hydraulic cylinder 1 against the external force is lowered. Therefore, when the pilot check valve 280 is closed, the return oil does not flow to the main tank passages 117B and 217B. As a result, it is possible to suppress the increase in the leakage amount of the pressure oil that has passed through the first notch 61, and it is possible to sufficiently support the external force acting on the hydraulic cylinder 1. [

Since part of the return oil from the head side oil chamber 1B of the hydraulic cylinder 1 can be supplied to the rod side oil chamber 1A through the regeneration passage, The supply shortage can be compensated for and cavitation can be prevented.

The present invention is not limited to the above-described embodiments, and includes various modifications to the above-described embodiments within the scope not departing from the gist of the present invention. For example, even in the case of a hydraulic control valve using one spool of the first embodiment, as in the second embodiment, a check valve can be inserted into the spool to constitute a regeneration passage.

In the above-described embodiment, the back pressure check valve 5 is used as the back pressure maintaining means, but other back pressure maintaining means may be used.

In the above-described embodiment, the spool (50, 150, 250) itself is provided with communication switching means for connecting and disconnecting the head side power supply passages 16B, 116B, 216B to the sub tank passages 19, 119, 219 However, the communication switching means may be provided separately from the direction switching spools 50, 150, and 250. In this case, when the pressure control of the hydraulic cylinder 1 is controlled by the switching operation of the spools 50, 150 and 250, the sub tank passages 19, 119, 219 are interlocked with each other. The return oil from the head side oil chamber 1B can be easily returned to the tank T with a small pressure loss at the time of contraction operation of the hydraulic cylinder 1. [

According to at least one embodiment described above, the return oil from the head side oil chamber 1B is supplied to the main tank passages 17B, 117B, 217B and the sub tank passages 19, 19B during the shrinking operation of the hydraulic cylinder 1. [ 119 and 219 to the tank T through the passage on both sides. Therefore, the pressure loss of the return oil can be reduced as compared with the case where the return oil is discharged to the tank T only through the main tank passages 17B, 117B, and 217B. In particular, the sub tank passages 19, 119 and 219 return the return oil from the head side oil chamber 1B directly to the tank T without passing through the back pressure check valve 5, can do.

The return oil from the head side oil chamber 1B is branched into both the main tank passages 17B, 117B and 217B and the sub tank passages 19, 119 and 219 in the valve body 11 It is flowing. As compared with the case where the quick return circuit for quickly returning the return oil from the head side oil chamber 1B to the tank T is separately provided outside the hydraulic control valves 10 and 100, It can be simplified. That is, the valve body 11, 111 of the hydraulic control valve 10 is provided with a sub tank for directly returning the return oil to the tank T without passing through the back pressure check valve separately from the main tank passages 17B, 117B, And tank passages 19, 119, and 219 are provided. Therefore, it is not necessary to provide the quick return circuit separately from the hydraulic control valves 10, 100, and the circuit configuration can be simplified.

While several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and alterations can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope of the invention and equivalents thereof as long as they are included in the scope and spirit of the invention.

1: Hydraulic cylinder
1A: Rod side oil chamber
1B: head side oil chamber
1P: piston
3: Hydraulic pump
5: Back pressure check valve (back pressure maintaining means)
10: Hydraulic control valve
11: Valve body
12A: rod side supply port
12B: Head side supply port
13: pump passage
14A, 14B: first tank passage
15A: rod side bridge passage
15B: head side bridge passage
16A: rod side supply passage
16B: head side supply passage
17A, 17B: main tank passage
18:
19: sub tank passage
20: Load check valve
40: sleeve hole
50: spool
61: First notch
62: Second notch
70: Positioning mechanism
100: Hydraulic control valve
111: Valve body
112A: rod side supply port
112B: Head side supply port
113: pump passage
114A, 114B: first tank passage
115A: rod side bridge passage
115B: head side bridge passage
116A: rod side supply passage
116B: head side supply passage
117A, 117B: main tank passage
118:
119: sub tank passage
120: Load check valve
140: Sleeve hole
150: spool
213: pump passage
214A, 214B: first tank passage
215A: rod side bridge passage
215B: head side bridge passage
216A: rod side supply passage
216B: head side supply passage
217A, 217B: main tank passage
218:
219: sub tank passage
220: Load check valve
240: Sleeve hole
250: spool
260: Check valve
280: Pilot check valve
Pa: Pilot port for A position switching
Pb: Pilot port for B position switching
PA, PB: Pilot pressure

Claims (7)

A hydraulic control valve provided between the hydraulic cylinder and the hydraulic pump and provided between the hydraulic cylinder and the tank and having a valve body for controlling the pressure drop across the hydraulic cylinder by a switching operation,
The valve body includes:
A head side power supply passage connected to the head side oil chamber of the hydraulic cylinder,
A main tank passage connected to the tank through back pressure maintaining means,
And a sub tank passage directly connected to the tank without passing through back pressure maintenance means,
The head side power supply passage into which the return oil from the head side oil chamber of the hydraulic cylinder flows is provided on both sides of the main tank passage and the sub tank passage Hydraulic control valve in communication. The method according to claim 1,
Inside the valve body,
A spool for communicating the head-side acute supply passage with the main tank passage in a state in which the hydraulic cylinder is switched to a position for actuating the hydraulic cylinder to the contraction side is provided so as to be slidable,
Tank communication passage for communicating the head-side power supply passage with the sub-tank passage in a state in which the spool is switched to a position for operating the hydraulic cylinder to the contraction side. 3. The method of claim 2,
And the communication switching means is provided on the spool. The method of claim 3,
A first notch for communicating the head side power supply passage with the main tank passage on the outer periphery of the flow path closing land portion on the spool in a state in which the spool shifts to a position for operating the hydraulic cylinder to the contraction side, And a second notch communicating the head side acute passage with the sub tank passage. 5. The method of claim 4,
A pilot check valve is provided to any one of a flow path in front of the first notch for communicating the head side acute supply passage to the main tank passage and a flow path in front of the second notch for communicating the head side acute supply passage to the sub tank passage. Hydraulic control valve with valve installed. The method according to claim 4 or 5,
The valve body is provided with a rod side supply passage connected to the rod side oil chamber of the hydraulic cylinder,
Wherein a part of the return oil flowing into the head side acute supply passage in a state in which the spool moves to the position for operating the hydraulic cylinder to the contraction side is provided inside the valve body or inside the spool, And a regeneration passage which is introduced into the rod side supply passage is provided. A hydraulic pressure control valve that is installed between the hydraulic cylinder and the hydraulic pump and installed between the hydraulic cylinder and the tank and controls switching of the pressure of the hydraulic cylinder relative to the hydraulic cylinder, In one hydraulic control circuit,
The hydraulic control valve is the hydraulic control valve according to any one of claims 1 to 6,
Wherein the main tank passage of the hydraulic control valve is connected to the tank through a back pressure check valve serving as the back pressure maintaining means for keeping the pressure of the main tank passage constant.

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