JP2015048858A - Hydraulic circuit of construction machine, and construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction machine or a hydraulic circuit of the construction machine, regenerating a return oil from a hydraulic cylinder by using a regeneration valve and a regeneration release valve arranged in a regeneration oil passage mounted near the hydraulic cylinder.SOLUTION: A hydraulic circuit of a construction machine for operating an attachment by driving a hydraulic cylinder, includes: a regeneration oil passage for regenerating a return oil from the hydraulic cylinder; and a spool disposed in the regeneration oil passage, and having a first seal portion at one end, and a second seal portion at the another end. The regeneration oil passage is mounted on the attachment, the spool switches a return oil supply destination by opening and closing a passage of a pressure oil by the second seal portion while keeping airtightness of one end by the first seal portion by axial movement of the spool.

Description

  The present invention relates to a hydraulic circuit of a construction machine and a construction machine.

  Some construction machines supply pressure oil to expand and contract a hydraulic cylinder, and the attachment is driven by the expanded and contracted hydraulic cylinder. Some hydraulic circuits of construction machines supply (regenerate) so-called return oil from the hydraulic cylinder to the hydraulic cylinder again in order to improve the operability of the attachment.

  Patent Document 1 discloses a technique relating to a regeneration hydraulic circuit (hydraulic circuit) that selectively regenerates return oil from a hydraulic cylinder using a regeneration function valve (regeneration valve).

Japanese Patent Laid-Open No. 06-117415

  In the technique disclosed in Patent Document 1, when a regeneration valve (regeneration function valve) is arranged in the vicinity of the hydraulic cylinder in order to shorten the return oil passage to be regenerated and reduce pressure loss, It is necessary to prevent leakage. However, Patent Document 1 does not disclose a technique for preventing the regeneration valve from leaking.

  Further, in the technique disclosed in Patent Document 1, when the construction machine is not regenerated at the time of excavation, for example, the pressure oil (return oil) is discharged through the CT opening narrowed by the control valve. For this reason, in the technique disclosed in Patent Document 1, the pressure loss of the pressure oil that passes through the control valve increases, and the excavation performance (such as the driving force and driving speed of the hydraulic cylinder) of the construction machine may decrease. is there.

  The present invention has been made under such circumstances, and is a construction machine or a hydraulic circuit of a construction machine in which a regeneration oil passage is mounted in the vicinity of a hydraulic cylinder, and includes a regeneration valve and a regeneration release valve disposed in the regeneration oil passage. An object of the present invention is to provide a construction machine or a hydraulic circuit that regenerates return oil from a hydraulic cylinder.

  According to one aspect of the present invention, there is provided a hydraulic circuit for a construction machine that drives a hydraulic cylinder to operate an attachment, the regeneration oil path that regenerates return oil from the hydraulic cylinder, and the hydraulic oil circuit that is disposed in the regeneration oil path. And a spool having a first seal portion at one end and a second seal portion at the other end, the reclaimed oil passage is mounted on the attachment, and the spool extends in the axial direction of the spool. By moving, the pressure seal passage is opened and closed by the second seal portion while maintaining the airtightness of the one end by the first seal portion, and the supply destination of the return oil is switched. A hydraulic circuit for a construction machine is provided. The hydraulic circuit may be characterized in that the first seal portion is an O-ring and the second seal portion is an inclined portion. The spool may be a hydraulic circuit that is moved in the axial direction in accordance with an operation amount of an operation lever that controls driving of the hydraulic cylinder. The regenerative oil passage is arranged side by side with the hydraulic cylinder, and the return oil flowing out from the rod side of the hydraulic cylinder is supplied to the bottom side of the hydraulic cylinder. Good.

  Moreover, according to the other aspect of this invention, a construction machine provided with any one of said hydraulic circuit is provided.

  According to the construction machine or the hydraulic circuit of the construction machine according to the present invention, the return oil from the hydraulic cylinder can be regenerated using the regeneration oil passage, the regeneration valve, and the regeneration release valve mounted in the vicinity of the hydraulic cylinder.

1 is a schematic external view showing an example of a construction machine according to an embodiment of the present invention. It is an external view explaining an example of arrangement | positioning of the reproduction | regeneration circuit of the construction machine which concerns on embodiment of this invention. 1 is a schematic hydraulic circuit diagram illustrating an example of a hydraulic circuit of a construction machine according to an embodiment of the present invention. It is explanatory drawing explaining an example of the regeneration valve used for the regeneration oil path of the construction machine which concerns on embodiment of this invention. It is explanatory drawing explaining an example of the regeneration cancellation | release valve used for the regeneration oil path of the construction machine which concerns on embodiment of this invention. It is a schematic hydraulic circuit diagram which shows the other example (comparative example) of the hydraulic circuit of a construction machine.

  Non-limiting exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the description of all attached drawings, the same or corresponding members or parts are denoted by the same or corresponding reference numerals, and redundant description is omitted. Also, the drawings are not intended to show the relative ratio between members or parts. Accordingly, specific dimensions can be determined by one skilled in the art in light of the following non-limiting embodiments.

  Hereinafter, the present invention will be described using the construction machine 100 according to the embodiment. In addition to the present embodiment, the present invention is a hydraulic circuit or machine, device, or system that reuses return oil from a hydraulic cylinder using a regeneration valve (for example, a switching valve) and a regeneration release valve. Any of them can be used. Construction machines that can use the present invention include hydraulic excavators, crane trucks, bulldozers, wheel loaders and dump trucks, pile driving machines, pile removers, water jets, mud drainage treatment equipment, grout mixers, deep Includes foundation and drilling machines.

  The present invention will be described in the following order using the construction machine 100 according to the embodiment.

1. Construction machinery Hydraulic circuit of construction machine [1. Construction machinery]
A schematic configuration of the construction machine 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a schematic external view showing an example of the construction machine 100 according to the present embodiment. FIG. 2 is an example of the arrangement of the regeneration circuit 20 of the construction machine 100 and is an enlarged view for explaining a region Ra in FIG.

  As shown in FIG. 1, the construction machine 100 according to the present embodiment includes an upper swing body 10Up on which a cab (cab) 10Cb is mounted, and a lower traveling body 10Dw that moves the construction machine 100 using wheels and the like. Prepare. Further, the construction machine 100 includes, as an attachment, a boom 11 whose base end is pivotally supported by the upper swing body 10Up, an arm 12 pivotally supported by the distal end of the boom 11, and a bucket pivotally supported by the distal end of the arm 12. 13. Furthermore, the construction machine 100 includes, as hydraulic cylinders, a boom cylinder 11c that drives the boom 11, an arm cylinder 12c that drives the arm 12, and a bucket cylinder 13c that drives the bucket 13.

  In addition, the construction machine which can use this invention may use attachments other than said boom 11, the arm 12, and the bucket 13 as an attachment to attach.

  The construction machine 100 according to this embodiment extends and contracts the boom cylinder 11c in the longitudinal direction by supplying hydraulic oil (pressure oil) to the boom cylinder 11c. At this time, the boom 11 is driven in the vertical direction in front of and above the cab 10Cb by expansion and contraction of the boom cylinder 11c. Further, the construction machine 100 controls the boom direction control valve in accordance with the operation amount (and operation direction) of an operation lever (for example, Lvr in FIG. 3 described later) of an operator (driver, operator) in the cabin of the cab 10Cb. The hydraulic oil supplied to the boom cylinder 11c is controlled. As a result, the construction machine 100 can perform a desired work according to the operation amount of the operation lever of the operator.

  As in the case of the boom 11, the construction machine 100 drives the arm 12 and the bucket 13 in front of and / or above the cab 10Cb by expansion and contraction of the arm cylinder 12c and the bucket cylinder 13c. As in the case of the boom cylinder 11c, the construction machine 100 controls the hydraulic oil supplied to the arm cylinder 12c and the bucket cylinder 13c by the arm direction control valve and the bucket direction control valve. Moreover, the construction machine 100 according to the present embodiment uses the wheels of the lower traveling body 10Dw and the turning motor 14m to run the construction machine 100 (moving back and forth and from side to side) and rotate the upper turning body 10Up (turning operation). .

  The construction machine 100 according to the present invention uses the regeneration circuit 20 (FIG. 2) to re-supply the return oil from the hydraulic cylinder to the hydraulic cylinder (hereinafter referred to as “regeneration”). As shown in FIG. 2, the construction machine 100 supplies pressure oil to the arm cylinder 12c (the bottom 12cb or the rod 12cr thereof) via an oil passage (P-Cb or P-Cr). In the present embodiment, the construction machine 100 regenerates the return oil from the arm cylinder 12c (the rod side in the present embodiment) using the regeneration circuit 20 mounted on the boom 11. In the construction machine to which the present invention can be used, the mounting position (or arrangement position) of the regeneration circuit 20 is appropriately set according to the attachment to be attached and the hydraulic cylinder to which the return oil to be regenerated is supplied.

  The regeneration circuit 20 is a circuit that regenerates the return oil from the hydraulic cylinder (in this embodiment, the arm cylinder 12c). In this embodiment, the regeneration circuit 20 includes a regeneration oil passage 21, a regeneration valve 22, and a regeneration release valve 23. Further, the reproduction circuit 20 is mounted on an attachment (the boom 11 in the present embodiment). Note that the reproduction circuit 20 may be arranged near or inside the attachment.

  The regeneration oil passage 21 is an oil passage through which return oil from the hydraulic cylinder is circulated. In this embodiment, the regenerated oil passage 21 is arranged alongside the arm cylinder 12c (hydraulic cylinder) (FIG. 2). The reclaimed oil passage 21 is mounted on the boom 11 (attachment). Further, the regenerated oil passage 21 supplies the return oil flowing out from the rod side (12cr in the figure) of the arm cylinder 12c to the bottom side (12cb in the figure) of the arm cylinder 12c.

  As a result, the construction machine 100 according to the present invention does not need to regenerate the return oil via a control valve or the like, and therefore uses the reclaimed oil path 21 and the oil path (oil path through which the regenerated pressure oil flows). Can be shortened, and the pressure loss of the pressure oil (return oil) can be reduced.

  The regeneration valve 22 is a valve that controls whether or not to regenerate the return oil from the hydraulic cylinder. As shown in FIG. 2, the regeneration valve 22 is disposed on the rod side 12cr of the arm cylinder 12c. The regeneration valve 22 controls the amount of the return oil that has flowed out from the rod side of the arm cylinder 12c to the bottom side by adjusting the opening area according to the operating state of the arm operation lever, for example. As the regeneration valve 22, for example, a switching valve, an electromagnetic valve, or the like may be used.

  An example of the regenerative valve according to the present invention will be described with reference to FIG. The regeneration valve that can be used in the present invention is not limited to the one shown in FIG.

  As shown in FIG. 4, the regeneration valve 22 according to the present embodiment includes a spool 30A. The spool 30A includes a first seal portion 31 at one end and a second seal portion 32 at the other end. In addition, the spool 30A is provided with an output pressure (arm pulling side) of the operating lever for performing a regenerating operation at one end, and a spring portion 33s for biasing the spool 30A against the output pressure of the operating lever at the other end. Is provided. Furthermore, the regeneration valve 22 (spool 30A) is disposed in the regeneration oil passage 21 (FIG. 3 described later).

  In this embodiment, the spool 30A uses an O-ring as the first seal portion 31. The spool 30 </ b> A uses an inclined surface as the second seal portion 32. As a result, when the spool 30A is moved in the axial direction of the spool, the O-ring (first seal portion 31) maintains the airtightness at one end and the pressure on the inclined surface (second seal portion 32). The oil passage can be opened and closed. Further, the spool 30A can prevent pressure oil from leaking by maintaining the airtightness of one end with an O-ring and closing the pressure oil passage on the inclined surface. Thereby, the spool 30A can also have a function equivalent to the holding valve Vsp.

  The spool that can be used in the present invention is any one that can open and close the pressure oil passage at the other end while maintaining the airtightness at the other end when the spool is moved in the axial direction. A spool having a shape of can be used.

  In the case of the position shown in FIG. 4A, the spool 30A blocks communication between the rod side and the bottom side of the hydraulic cylinder in the regenerated oil passage 21. As a result, the hydraulic oil is introduced to the rod side of the hydraulic cylinder via the direction control valve Vc. That is, the regeneration valve 22 (construction machine 100) does not regenerate the return oil in the case of FIG.

  Further, when the spool 30A is at the position shown in FIG. 4B, the output pressure (arm pulling side) of the operation lever Lvr is input to one end and moved in the axial direction (Mb in the drawing). At this time, the spool 30A is arranged at a position moved in the axial direction in balance with the urging force of the spring portion 33s. As a result, the spool 30A maintains the airtightness at one end with the O-ring, and opens the passage of the pressure oil on the inclined surface, thereby connecting the rod side and the bottom side of the hydraulic cylinder (Fb in the figure). That is, the regeneration valve 22 (construction machine 100) regenerates the return oil in the case of FIG.

  As described above, the construction machine 100 according to the present invention uses the regeneration valve 22 to control whether or not to regenerate the return oil in the vicinity of the hydraulic cylinder (in this embodiment, the arm cylinder 12c) and the amount to be regenerated. Can do. For this reason, the construction machine 100 can shorten the oil passage (the oil passage through which the regenerated pressure oil flows). Moreover, since the construction machine 100 can shorten the oil passage (the oil passage through which the regenerated pressure oil flows), the pressure loss of the pressure oil (return oil) can be reduced.

  The regeneration cancellation valve 23 is a valve that switches the supply destination of return oil via the regeneration valve 22. As shown in FIG. 2, the regeneration cancellation valve 23 is disposed on the downstream side of the regeneration oil passage 21. In the present embodiment, the regeneration release valve 23 switches whether to regenerate the return oil or discharge it to the tank according to the load of the arm 12 (attachment).

  Thereby, the construction machine 100 according to the present invention can control whether to regenerate the return oil that has passed through the regeneration valve 22 by using the regeneration cancellation valve 23. Moreover, the construction machine 100 according to the present invention can control the operation of regenerating the return oil according to the work state or work operation (for example, excavation operation) of the construction machine.

  In this embodiment, the regeneration release valve 23 switches the supply destination of the return oil using the pressure of the hydraulic oil supplied from the hydraulic pump Pmp (FIG. 3 described later) to the bottom side of the arm cylinder 12c (hydraulic cylinder). . When the pressure on the bottom side of the arm cylinder 12c is low, the regeneration release valve 23 closes the opening, for example, to regenerate the return oil. Further, when the pressure on the bottom side of the arm cylinder 12c is high, the regeneration release valve 23 opens an opening and discharges the return oil downstream (for example, a hydraulic oil tank) so as not to regenerate the return oil, for example. .

  Note that the opening of the regeneration release valve 23 may be controlled in accordance with a command of a controller mounted in advance on the construction machine 100.

  An example of the regeneration release valve used in the regeneration circuit of the construction machine according to the present invention will be described with reference to FIG. The regeneration cancellation valve according to the present invention is not limited to that shown in FIG.

  The regeneration circuit 20 (FIG. 5) according to the present embodiment is mounted on the boom 11 as shown in FIG. Further, the regeneration release valve 23 of the regeneration circuit 20 according to the present embodiment is disposed on the bottom side 12cb of the arm cylinder 12c as shown in FIG. Furthermore, the regeneration circuit 20 according to the present embodiment flows hydraulic oil (Vc-Cy in the drawing) supplied from the direction control valve Vc (FIG. 3 to be described later) into the bottom side of the arm cylinder 12c.

  As shown in FIG. 5, the regeneration circuit 20 includes a spool 30 </ b> B that controls the flow direction of pressure oil (switches the supply destination) inside the regeneration release valve 23. Further, the regeneration circuit 20 includes therein a throttle 24 and a check valve 25 that control the flow (pressure, flow rate, etc.) of pressure oil flowing from the rod side of the arm cylinder 12c.

  When regenerating the return oil, the regeneration circuit 20 re-supplys the pressure oil (Cy1-R in the figure) flowing out from the rod side of the arm cylinder 12c to the bottom side of the arm cylinder 12c (Cy-B in the figure). . At this time, the regeneration circuit 20 uses the throttle 24 and the check valve 25 to control the flow rate and pressure of the pressure oil to be resupplied to the bottom side of the arm cylinder 12c.

  Further, the regeneration circuit 20 uses the pressure input to one end of the spool 30B (regeneration release valve 23) (pressure of the pressure oil on the bottom side of the arm cylinder 12c) when the return oil is not regenerated. Move in the direction and change its opening shape. As a result, the regeneration circuit 20 uses the regeneration release valve 23 to cause the pressure oil (Cy2-R in the figure) flowing out from the rod side of the arm cylinder 12c to pass through the opening formed by the moved spool 30B. The oil can be discharged into the hydraulic oil tank (Cy-T in the figure).

[2. Hydraulic circuit of construction machinery]
The hydraulic circuit 100C of the construction machine 100 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic hydraulic circuit diagram showing an example of the hydraulic circuit 100C according to the present embodiment.

  In addition, the continuous line described in FIG. 3 shows an oil path (pressure oil path). A dotted line shows the oil path of a pilot circuit (remote control circuit). Further, in FIG. 3, the reproducing circuit 20 is mainly shown to explain the present invention, and other parts (for example, an electric control system of the controller) are omitted. Furthermore, the present invention can be used for any circuit other than the hydraulic circuit 100C shown in FIG. 3 as long as it uses the regeneration circuit 20 to regenerate the return oil from the hydraulic cylinder.

  As shown in FIG. 3, the hydraulic circuit 100C includes a hydraulic pump Pmp that discharges pressure oil (hydraulic oil), a direction control valve Vc that is supplied with the pressure oil discharged from the hydraulic pump Pmp, and a direction control valve Vc. And a hydraulic cylinder Cy arranged on the downstream side. The hydraulic circuit 100C includes a pilot pump Pmp-PL that generates a pilot pressure that is input to the control port of the directional control valve Vc. Furthermore, the hydraulic circuit 100 </ b> C according to the present invention further includes a regeneration circuit 20 including a regeneration oil passage 21, a regeneration valve 22, and a regeneration release valve 23.

  The hydraulic circuit 100C according to the present embodiment controls the operation of supplying (inputting) the pressure oil discharged from the hydraulic pump Pmp to the direction control valve Vc by controlling the operation of the hydraulic pump Pmp. Further, the hydraulic circuit 100C controls the operation of the pilot pump Pmp-PL to control the operation of the direction control valve Vc, so that the hydraulic cylinder Cy (11c, 12c and 13c in FIG. 1) from the direction control valve Vc, and The flow rate and direction of hydraulic oil (pressure oil) supplied (inflow) to the hydraulic motor (14m in FIG. 1) are controlled. Further, the hydraulic circuit 100C uses the regeneration circuit 20 to control the operation of regenerating the return oil from the hydraulic cylinder Cy.

  The hydraulic circuit 100C has a check valve (check valve) 25 that restricts the flow of pressure oil to be regenerated in one direction (the direction of flowing into the bottom side) in the oil path between the regenerator valve 22 and the hydraulic cylinder Cy. Have As a result, the hydraulic circuit 100C prevents backflow of the pressure oil when the pressure on the bottom side of the hydraulic cylinder Cy becomes high. The hydraulic circuit 100C may further include a throttle 24 that restricts the flow (pressure, flow rate, etc.) of the regenerated pressure oil (return oil) in the oil path between the regenerative valve 22 and the hydraulic cylinder Cy. .

  The hydraulic pump Pmp discharges pressure oil (operating oil) flowing into the hydraulic cylinder Cy. The hydraulic pump Pmp may be configured to be mechanically connected to an output shaft of a power source (such as a prime mover, an engine, and a motor) (not shown) and discharge pressure oil using the power of the power source.

  The direction control valve Vc controls the flow rate and flow direction of the pressure oil (hydraulic oil) supplied to the boom cylinder 11c, the arm cylinder 12c or the bucket cylinder 13c, or the turning motor 14c. The directional control valve controls the flow rate and flow direction of the pressure oil supplied (inflowed) to the hydraulic cylinder (or hydraulic motor) based on the pilot pressure (remote control pressure) input to the control port. In FIG. 3, a plurality of directional control valves corresponding to each hydraulic cylinder are omitted, and only one directional control valve is illustrated. In FIG. 3, the shape of the spool of the direction control valve is omitted.

  The hydraulic cylinder Cy drives an attachment (such as 11 in FIG. 1) by its expansion and contraction operation. The hydraulic cylinder Cy expands and contracts in the longitudinal direction using the pressure oil (hydraulic oil) supplied from the direction control valve Vc. As shown in FIG. 1, in the construction machine 100 of the present embodiment, the hydraulic cylinder Cy includes a boom cylinder 11 c that drives the boom 11, an arm cylinder 12 c that drives the arm 12, and a bucket cylinder 13 c that drives the bucket 13. Is provided.

  Further, as shown in FIG. 3, the hydraulic cylinder Cy is disposed downstream of the directional control valve Vc and between an oil passage Ocb connected to the bottom side and an oil passage Ocr connected to the rod side ( Is included).

  The hydraulic cylinder Cy can be composed of a cylinder container and a piston. The hydraulic cylinder Cy is supplied with hydraulic oil (pressure oil) to a bottom side (head side, push side) chamber and a rod side (pull side) chamber. When hydraulic oil is supplied to the bottom side, the hydraulic cylinder Cy moves a built-in piston or the like in the pushing direction and extends in the longitudinal direction. Further, when hydraulic oil is supplied to the rod side, the hydraulic cylinder Cy moves the built-in piston or the like in the pulling direction and contracts in the longitudinal direction.

  As shown in FIG. 3, the regeneration circuit 20 according to the present invention includes a regeneration oil passage 21, a regeneration valve 22, and a regeneration release valve 23, and flows out from the rod side of the hydraulic cylinder (arm cylinder 12c in this embodiment). Re-supply the return oil to the bottom side. The configurations of the regeneration oil passage 21, the regeneration valve 22, and the regeneration cancellation valve 23 are the same as those described in [1. Since the configuration is the same as that described in [Construction Machine], the description is omitted.

  The hydraulic circuit 100C of the construction machine 100 is configured to be connected to a controller (not shown) for controlling the operation of the construction machine 100. Here, the controller can be composed of an arithmetic processing unit including a CPU and a memory (ROM, RAM, etc.).

  As described above, according to the construction machine 100 (hydraulic circuit 100C) according to the present embodiment, the return is achieved by opening and closing the second seal portion 32 by moving the spool 30A (regeneration release valve 23) in the axial direction. The oil supply destination can be switched. Further, according to the construction machine (hydraulic circuit 100C) according to the present embodiment, when the regenerative oil passage 21 (spool 30A) is arranged in the vicinity of the hydraulic cylinder, the first seal portions 31 and the first seal portions 31 at both ends of the spool 30A are arranged. By using the two seal portions 32, it is possible to prevent leakage of pressurized oil from the regenerated oil passage 21 (for example, both ends of the spool 30 </ b> A). Thereby, the construction machine according to the present embodiment can arrange the regenerated oil passage 21 (regeneration circuit 20) in the vicinity of the hydraulic cylinder and shorten the regenerated oil passage 21, so that the pressure loss of the return oil to be regenerated is reduced. Can be reduced.

  FIG. 6 shows a schematic hydraulic circuit diagram for explaining another example (comparative example) of the hydraulic circuit of the construction machine.

  As shown in FIG. 6, the hydraulic circuit of the other example regenerates the return oil via the control valve as compared with the hydraulic circuit 100C (FIG. 3) of the present invention. Energy loss occurs. In addition, the hydraulic circuit of another example is different from the hydraulic circuit 100C of the present invention (for example, FIG. 2) according to the regenerative oil passage (the oil through which the regenerated pressure oil flows) according to the separation distance between the control valve and the hydraulic cylinder. (Path) becomes longer, the pressure loss of the pressure oil (return oil) increases.

  As described above, the embodiment of the construction machine and the hydraulic circuit thereof according to the present invention has been described, but the present invention is not limited to the above-described embodiment. The present invention can be variously modified or changed in light of the appended claims.

100: Construction machine 100C: Hydraulic circuit 10Cb: Cab (operating room, etc.)
10Up: Upper turning body 10Dw: Lower traveling body 11: Boom (attachment)
11c: Boom cylinder (hydraulic cylinder)
12: Arm (attachment)
12c: Arm cylinder (hydraulic cylinder)
13: Bucket (attachment)
13c: Bucket cylinder (hydraulic cylinder)
14m: slewing motor 20: regeneration circuit 21: regeneration oil passage 22: regeneration valve (switching valve etc.)
23: Regeneration release valve 24: Restriction 25: Check valve (check valve)
30A, 30B: Spool 31: First seal portion (O-ring, etc.)
32: Second seal part (inclined part, etc.)
33s: Spring part Cy: Hydraulic cylinder Lvr: Operation lever Pmp: Hydraulic pump Pmp-PL: Pilot pump Tnk: Tank (hydraulic oil tank, etc.)
Vc: Directional control valve (control valve, etc.)

Claims (5)

A hydraulic circuit of a construction machine that drives a hydraulic cylinder to operate an attachment,
A regeneration oil passage for regenerating the return oil from the hydraulic cylinder;
A spool that is disposed in the reclaimed oil passage, includes a first seal portion at one end, and a second seal portion at the other end;
The regenerated oil passage is mounted on the attachment,
The spool moves in the axial direction of the spool to open and close the passage of pressure oil at the second seal portion while maintaining the airtightness of the one end at the first seal portion, and to return the spool. Switch the oil supply destination,
A hydraulic circuit of a construction machine characterized by the above. The first seal portion is an O-ring;
The second seal part is an inclined part.
The hydraulic circuit for a construction machine according to claim 1, wherein The spool is moved in the axial direction in accordance with an operation amount of an operation lever that controls driving of the hydraulic cylinder.
The hydraulic circuit for a construction machine according to claim 2, wherein: The regenerative oil passage is arranged side by side with the hydraulic cylinder, and supplies the return oil flowing out from the rod side of the hydraulic cylinder to the bottom side of the hydraulic cylinder.
The hydraulic circuit for a construction machine according to any one of claims 1 to 3, wherein the hydraulic circuit is for a construction machine.   A construction machine comprising the hydraulic circuit according to any one of claims 1 to 4.

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