JP3595148B2 - Regeneration circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reproduction circuit used for a construction machine or the like.
[0002]
[Prior art]
As shown in FIG. 3, in the hydraulic excavator, an upper revolving unit c is rotatably provided on a lower traveling unit a via a revolving unit b, and a front work machine d is provided on the upper revolving unit c.
[0003]
In the front work machine d, a base end of a boom e is rotatably supported by an upper revolving unit c, an arm f is rotatably supported at a distal end of the boom e, and a bucket is provided at a distal end of the arm f. g is rotatably supported.
[0004]
The boom e is rotated by a boom cylinder h, the arm f is rotated by an arm cylinder i, and the bucket g is rotated by a bucket cylinder j.
[0005]
In the following description, the term “arm-in” means a movement of operating the arm cylinder i of the hydraulic excavator in the extending direction and pulling the arm f in the direction in which the cab k is located. The term "arm out" means a movement in which the arm cylinder i is operated in the contracting direction and the arm f is turned away from the cab k.
[0006]
FIG. 4 shows an example of a hydraulic circuit in which an arm-in regeneration circuit is provided in a conventional pilot-operated control valve. In the following description, a line means an oil passage of hydraulic oil for operating an actuator or pilot oil for operating a valve.
[0007]
In this conventional hydraulic circuit, when a pilot pressure is supplied to an arm extension operating pilot line 2 in an arm switching main spool 1a of a pilot operated control valve 1, the main spool 1a slides rightward on the paper. The pressure oil supplied from the hydraulic pressure source 3 flows into a head chamber 6 of an arm cylinder 5 through a main line 4 (hereinafter, this main line is referred to as a “head line”) on the cylinder head side, and a rod chamber. The oil in 7 flows out to the tank line 9 through the main line 8 on the cylinder rod side (hereinafter, this main line is referred to as “rod line”), and the rod 10 moves in the extending direction (rightward).
[0008]
At this time, when the pilot pressure is supplied to the pilot pressure action chamber of the arm regeneration valve 12 through the pilot line 11 branched from the arm extension operation pilot line 2, the regeneration spool of the arm regeneration valve 12 is raised above the paper surface. When the internal pressure of the head chamber 6 is lower than the internal pressure of the rod chamber 7, for example, when the arm f is lowered by its own weight by the arm-in operation, a part of the return oil from the rod chamber 7 is transferred to the line 13 and the check valve. Since the gas passes through the valve 14 and further flows into the head chamber 6 of the arm cylinder 5 through the arm regeneration valve 12, the amount of oil supplied to the head chamber 6 is increased as compared with the case without this regeneration circuit, and the arm extension speed is reduced. Can be faster.
[0009]
At this time, the return oil control opening 15 of the main spool 1a is usually narrowed sufficiently to increase the amount of regenerated oil from the rod chamber 7 to the head chamber 6 and enhance the regenerating effect. When the pressure at 4 becomes higher than the pressure at the rod line 8 and the regenerative oil is blocked by the check valve 14 and the regeneration is stopped, the amount of oil passing through the throttle portion at the return oil control opening 15 of the main spool 1a increases. As a result, an excessive boost pressure is generated in the rod line 8.
[0010]
In order to prevent the generation of the excessive boost pressure, an unload valve 16 is provided to relieve the oil in the rod line 8 to the tank when the pressure in the head line 4 exceeds a certain value.
[0011]
The unload valve 16 operates when the operating pressure guided by the unloading pilot signal line 17 branched from the headline 4 exceeds the set pressure set by adjusting the biasing force of the spring 18. Then, the oil in the rod line 8 is discharged to the tank 20.
[0012]
[Problems to be solved by the invention]
In this conventional hydraulic circuit, when the pilot pressure is supplied to the arm contraction operation pilot line 2a by manually operating a remote control valve (not shown) to perform the arm-out operation, the operation pressure of the unload valve 16 is reduced to the headline. If the pressure is set lower than the pressure generated at 4, the rod line 8 serving as the pressure oil supply line at the time of the arm-out operation may be momentarily connected to the tank line 19 by the operation of the unload valve 16.
[0013]
In this case, the pressure in the rod chamber 7 of the arm cylinder 5 decreases, and a sudden change in the cylinder speed occurs. As a result, problems such as vibration of the arm cylinder 5 occur. The pressure must be set to a pressure sufficiently higher than the pressure of the headline 4 that can be generated during the arm-out operation.
[0014]
For this reason, the function of the unload valve 16 at the time of the original arm-in operation as described above, that is, the generation of the excessive boost pressure in the rod line 8 during the non-regeneration at the time of the arm-in operation is controlled by the unload valve 16. The function to be avoided is considerably restricted, and the return oil control opening 15 of the main spool 1a cannot be narrowed much.
[0015]
In other words, the amount of oil discharged to the tank line 9 via the return oil control opening 15 during the arm-in operation increases, and the amount of regenerated oil cannot be increased to sufficiently enhance the regenerating effect.
[0016]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to enable an optimum operating pressure to be set by an unload valve necessary for a regeneration circuit.
[0017]
[Means for Solving the Problems]
The invention described in claim 1 is operated by a control valve for controlling the direction of the working fluid and a working fluid passing through the control valve.Cylinder typeConnecting the hydraulic actuator to the control valve and the hydraulic actuatorHeadlineandRod lineWhen,HeadlineWhenRod lineFrom the control valveHeadlineOnly when the working fluid is supplied to theRod lineWorking fluidHeadlineA regeneration valve for regeneration toRod lineAn unload valve provided between the tank and the tank and operated by an unload pilot signal;HeadlineAnd a pilot signal control unit that connects the unload pilot signal line disposed from the first to the unload valve when the regeneration valve is operated and shuts off when the regeneration valve is not operated.
[0018]
And from the control valveHeadlineWhen the working fluid is supplied to the valve, the regeneration valve operates and the fluid pressure actuatorRod lineWorking fluid that has flowed out through the regeneration valveHeadlineWill be played. In this case, the pilot signal control unitHeadlineFrom the pilot signal line to the unload valve,HeadlineWhen the fluid pressure of the unload valve becomes higher than the set pressure of the unload valve, the unload valve operates,Rod lineThe working fluid is discharged from the tank to the tank.
[0019]
Meanwhile, from the control valveRod lineWhen the working fluid is supplied to the regenerating valve does not operate,Rod lineWhenHeadlineIs shut off by the regeneration valve. In this case, the pilot signal control unitHeadlineThe pilot signal line to the unload valve is also shut off, and the unload valve does not operate.Rod lineWhen supplying working fluid toHeadlineIrrespective of the pressure that is generated in the unloading valve, the operating pressure of the unload valve can be set to a value required to sufficiently enhance the regeneration effect.
[0020]
According to a second aspect of the present invention, the pilot signal control section in the regeneration circuit according to the first aspect is provided integrally with the regeneration valve.
[0021]
Then, the pilot signal control section is switched integrally with the regeneration valve, and the regeneration valve is operated, so that the fluid pressure actuatorRod lineWorking fluid flowing toHeadlineIs reproduced by the pilot signal control unit.HeadlineFrom the pilot signal line to the unload valve, and the regeneration valve does not operate.Rod lineWhenHeadlineIs shut off by the regeneration valve,HeadlineThe pilot signal line from the to the unload valve is also cut off by the pilot signal control unit.
[0022]
According to a third aspect of the present invention, in the reproduction circuit of the first aspect, the pilot signal control unit is provided integrally with the control valve.
[0023]
Then, the pilot signal control section is switched integrally with the control valve, and the control valve isHeadlineWhen the actuator is operated to supply working fluid to the hydraulic actuator viaRod lineWorking fluid flowing toHeadlineAnd reproduced by the pilot signal control unit.HeadlineFrom the pilot signal line to the unload valve, and the control valveRod lineWhen actuated to the side that supplies working fluid to the fluid pressure actuator via, the regeneration valve does not operate,Rod lineWhenHeadlineIs shut off by the regeneration valve,HeadlineThe pilot signal line from the to the unload valve is also cut off by the pilot signal control unit.
[0024]
The invention described in claim 4 is a hydraulic circuit in which the regeneration circuit according to any one of claims 1 to 3 regenerates hydraulic oil from a rod line to a headline in an arm cylinder of a hydraulic shovel.
[0025]
Then, at the time of arm-in operation in which hydraulic oil is supplied from the control valve to the headline, the regeneration valve operates and the pilot signal control unit connects the pilot signal line from the headline to the unload valve. When the operating oil pressure of the head line becomes higher than the set pressure of the unload valve, the unload valve operates and the operating oil is discharged from the rod line to the tank.
[0026]
On the other hand, during arm-out operation when hydraulic oil is supplied from the control valve to the rod line, the regeneration valve does not operate, and the pilot signal control unit also cuts off the pilot signal line from the headline to the unload valve, causing unloading. Since the valve does not operate, the operating pressure of this unload valve is adjusted to the value required to sufficiently enhance the regeneration effect, regardless of the pressure generated in the headline when hydraulic oil is supplied from the control valve to the rod line. Can be set to
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a hydraulic circuit of a construction machine according to the present invention will be described with reference to one embodiment shown in FIG. 1 and another embodiment shown in FIG. 2, respectively. Parts similar to those of the conventional circuit shown in FIG. 4 are denoted by the same reference numerals, and description thereof may be omitted. In the following description, a line means an oil passage of hydraulic oil for operating an actuator or pilot oil for operating a valve.
[0028]
First, the embodiment shown in FIG. 1 will be described.
[0029]
A pilot pressure is supplied from a remote-controlled valve (not shown) operated by an arm-in to the left and right pilot pressure action chambers of the arm switch main spool 1a of the pilot-operated arm control control valve (hereinafter referred to as control valve) 1. The pilot line 2 for operating the arm extension which receives the pressure and the pilot line 2a for operating the arm contraction which receives the supply of the pilot pressure from a remote control valve (not shown) whose arm is operated out are communicated with each other.
[0030]
The control valve 1 has a hydraulic oil supply port connected to a hydraulic pressure source 3 and a head chamber 4 of an arm cylinder 5 as a fluid pressure actuator through one head port 4 as one main pipe to one output port. 6, a rod chamber 7 of the arm cylinder 5 is connected to the other output port via a rod line 8 as the other main pipeline, and a tank line 9 is connected to the oil drain port.
[0031]
At the tip of the piston rod 10 protruding from the rod chamber 7 of the arm cylinder 5, a load such as the weight of the arm f and the bucket g and a load such as earth and sand in the bucket act as a load W in the arm-in direction.
[0032]
A pilot line 11 branches off from the pilot line 2 for arm extension operation, and the pilot line 11 communicates with a pilot pressure action chamber facing one end of a regeneration spool of a regeneration valve 12 for an arm (hereinafter referred to as an arm regeneration valve) 12. ing.
[0033]
The arm regeneration valve 12 is switched by sliding of a regeneration spool, and a position a that communicates a line 13 branched from a rod line 8 to a head line 4 via a check valve 14 and a passage in the regeneration valve. And a position b for interrupting communication.
[0034]
The main spool 1a is provided with a sufficiently small return oil control opening 15 to enhance the regeneration effect of regenerating hydraulic oil from the rod line 8 to the head line 4 via the arm regeneration valve 12.
[0035]
Due to the throttle resistance at the return oil control opening 15, an excessive boost pressure is generated in the rod line 8 during non-regeneration, in which the check valve 14 is locked due to a rise in the pressure of the headline 4 and regeneration is no longer performed. In order to prevent this, when the pressure of the headline 4 exceeds a certain value, an unload valve 16 for discharging the oil of the rod line 8 to the tank is provided on the rod line 8. It is connected.
[0036]
The unload valve 16 is activated when the operating pressure guided by the unloading pilot signal lines 17a and 17b from the head line 4 exceeds the set pressure set by a spring 18 which can be adjusted by screws or the like, as described below. Then, the unload operation is performed to connect the rod line 8 to the tank line 19. The tank line 19 is a drain oil passage connected to the tank 20.
[0037]
The arm regeneration valve 12 is integrally provided with a pilot signal control unit 21 for unloading. The pilot signal control unit 21 communicates unload pilot signal lines 17a and 17b provided from the headline 4 to the unload valve 16 when the arm regeneration valve 12 is operated and when the arm regeneration valve 12 is not operated. It shuts off.
[0038]
That is, the pilot signal control unit 21 for unloading, the regeneration spool of the arm regeneration valve 12, the pilot signal communication unit 22a that communicates the pilot signal to the unload valve 16, and the pilot signal to the unload valve 16 A pilot signal cutoff section 22b for cutting off, and a pilot signal communication section between a pilot signal line 17a branched from the headline 4 and a pilot signal line 17b connected to the unload valve 16; 22a or a pilot signal cutoff unit 22b is interposed.
[0039]
Pilot signal lines 17a and 17b are communicated by a pilot signal communication section 22a, and pilot signal lines 17a and 17b are cut off by a pilot signal cutoff section 22b. The signal line 17b is connected to the drain line 26 connected to the tank 20.
[0040]
When there is no pilot pressure in the pilot line 11, the regeneration spool of the arm regeneration valve 12 returns to the state shown in FIG. 1 by the return spring 27 provided on the opposite side.
[0041]
As described above, the regeneration circuit represented by the arm-in circuit also requires the unload valve 16, but the pilot signal line 17b to the unload valve 16 is connected to the arm regeneration valve 12 only when the regeneration operation is performed. The pilot signal line 17a on the headline 4 side of the arm cylinder 5 is connected to the pilot signal line 17a of the arm cylinder 5 via the pilot signal communication section 22a of the pilot signal control section 21 which operates integrally with the regeneration valve 12, and the arm regeneration valve 12 is connected to the spring return shown in FIG. When in the state, the circuit configuration is such that it is communicated with the drain line 26 via the internal passage 25 of the pilot signal control unit 21.
[0042]
Next, the operation of the embodiment shown in FIG. 1 will be described. The operation of the same part as that of the conventional example shown in FIG. 4 has already been described in detail, and the explanation of the operation is omitted here.
[0043]
A pilot pressure is supplied to the arm extension operation pilot line 2, and the switching operation of the main spool 1 a causes the pressure oil of the hydraulic pressure source 3 to flow into the head chamber 6 of the arm cylinder 5 through the head line 4, and the rod chamber 7. When the oil flows out to the tank line 9 via the rod line 8, the pilot pressure acts on the arm regeneration valve 12 through the pilot line 11 branched from the arm extension operation pilot line 2, and the arm regeneration valve 12 Is switched upward in FIG.
[0044]
At this time, while the head line 4 is at a lower pressure than the rod line 8, part of the return oil flowing out of the rod chamber 7 to the rod line 8 passes through the line 13 and the check valve 14, and furthermore, the position of the arm regeneration valve 12. A regeneration operation is performed in which the air flows into the head chamber 6 of the arm cylinder 5 through the internal passage a.
[0045]
When the arm regeneration valve 12 is operated, the pilot signal lines 17a and 17b from the head line 4 of the arm cylinder 5 to the unload valve 16 communicate through a pilot signal communication section 22a.
[0046]
On the other hand, when the arm regeneration valve 12 is in the inactive state shown in FIG. 1, the pilot signal lines 17a and 17b from the headline 4 to the unload valve 16 are cut off by the pilot signal cutoff unit 22b. Pilot signal line 17b communicates with drain line 26 through internal passage 25 of pilot signal control unit 21.
[0047]
As described above, the unload valve 16 can be operated only at the time of the arm-in operation in which the arm regeneration valve 12 operates, and at the time of neutrality and the arm-out operation of the main spool 1a in which the arm regeneration valve 12 does not operate. Since the pilot signal line 17b of the unload valve 16 communicates with the drain line 26 via the internal passage 25 of the pilot signal control unit 21, the unload valve 16 operates regardless of the head pressure of the arm cylinder 5. Never.
[0048]
Therefore, the operating pressure of the unload valve 16 does not need to be set sufficiently higher than the head pressure of the arm cylinder 5 that can be generated at the time of arm-out operation as in the related art. Can be demonstrated. For this reason, the return oil control opening 15 of the main spool 1a can be reduced as much as necessary to sufficiently enhance the regeneration effect.
[0049]
That is, during the arm-in operation, the amount of oil discharged to the tank line 9 through the return oil control opening 15 is sufficiently reduced, and accordingly, the rod line 8 passes through the line 13, the check valve 14, and the arm regeneration valve 12. The amount of regenerated oil regenerated in the head chamber 6 of the arm cylinder 5 can be increased, and a sufficient regenerating effect can be obtained.
[0050]
Next, the embodiment according to the present invention shown in FIG. 2 will be described. The configurations 1 to 20 are the same as those of the embodiment shown in FIG. 1, and therefore, the same reference numerals are given to those portions, and the description thereof will be omitted.
[0051]
The control valve 1 is integrally provided with a pilot signal control unit 21 for unloading. The pilot signal control section 21 communicates the pilot signal lines 17a and 17b provided from the head line 4 to the unload valve 16 when the arm regeneration valve 12 is operated and shuts off when the arm regeneration valve 12 is not operated. It is.
[0052]
That is, the pilot signal control unit 21 interrupts the pilot signal to the unload valve 16 and the pilot signal communication unit 22a to communicate the pilot signal to the unload valve 16 with the arm switching main spool 1a of the control valve 1. Pilot signal cutoff units 22b and 22c are additionally provided integrally, respectively, and are provided between a pilot signal line 17a branched from the headline 4 and a pilot signal line 17b connected to the unload valve 16. The pilot signal communication section 22a and the pilot signal cutoff section 22b or 22c are interposed.
[0053]
The pilot signal communication section 22a communicates the pilot signal lines 17a and 17b with the internal passage 24, and the pilot signal cutoff sections 22b and 22c cut off the pilot signal lines 17a and 17b and simultaneously unload the pilot signal lines 17a and 17b. The pilot signal line 17b connected to the valve 16 is connected to a drain line 26 connected to the tank 20.
[0054]
As described above, the regeneration circuit typified by the arm-in circuit also requires the unload valve 16, but the pilot signal line 17b to the unload valve 16 has a pilot signal line only when the regeneration operation of the arm regeneration valve 12 is performed. It is communicated with the head line 4 of the arm cylinder 5 via the internal passage 24 of the signal control unit 21 and the pilot signal line 17a.
[0055]
On the other hand, when the arm regeneration valve 12 is in the inactive state shown in FIG. 2, that is, when the arm contraction operation pilot line 2a receives the pilot pressure from the remote control valve (not shown), the arm out operation is performed. , And when the pilot pressure is not supplied to both pilot lines 2 and 2a, the pilot signal line 17b is connected to the drain line 26 via the internal passage 25 of the pilot signal control unit 21 in a neutral state.
[0056]
Next, the operation of the embodiment shown in FIG. 2 will be described. The operation of the same part as that of the conventional example shown in FIG. 4 has already been described in detail, and the explanation of the operation is omitted here.
[0057]
When the pilot pressure is supplied to the arm extension operation pilot line 2 by the arm-in operation and the main spool 1a of the control valve 1 is switched to the right in FIG. 2, the pressure oil of the hydraulic pressure source 3 passes through the head line 4. While flowing into the head chamber 6 of the arm cylinder 5, the oil in the rod chamber 7 flows out to the tank line 9 via the rod line 8.
[0058]
At the time of the arm-in operation, the pilot pressure acts on the arm regeneration valve 12 through the pilot line 11 branched from the arm extension operation pilot line 2, and the regeneration spool of the arm regeneration valve 12 is switched above the paper surface. While the headline 4 is at a lower pressure than the rod line 8, part of the return oil flowing out of the rod chamber 7 to the rod line 8 passes through the line 13 and the check valve 14, and further moves to the position a of the arm regeneration valve 12. Through the internal passage and the headline 4 to the head chamber 6 of the arm cylinder 5 to perform a regeneration operation.
[0059]
At the time of the arm-in operation, that is, at the time of operation of the arm regeneration valve 12, the unload pilot signal control unit 21 provided integrally with the main spool 1a of the control valve 1 is also switched to the pilot signal communication unit 22a. The pilot signal line 17b to the unload valve 16 communicates with the head line 4 of the arm cylinder 5 via the internal passage 24 of the pilot signal communication part 22a and the pilot signal line 17a.
[0060]
On the other hand, when the pilot pressure is not supplied to either of the pilot lines 2 and 2a and the main spool 1a of the control valve 1 and the arm regeneration valve 12 are in the neutral state or the inactive state shown in FIG. The pilot signal line 17b to the valve 16 communicates with the drain line 26 by the internal passage 25 of the pilot signal cutoff unit 22b of the pilot signal control unit 21.
[0061]
Further, the pilot pressure is supplied to the arm contraction operation pilot line 2a by the arm-out operation, and when the main spool 1a of the control valve 1 is switched to the left in FIG. 2, the pilot signal line 17b to the unload valve 16 becomes , Is communicated with the drain line 26 by the internal passage 25 of the pilot signal cutoff section 22c of the pilot signal control section 21.
[0062]
As described above, the pilot signal line 17b to the unload valve 16 communicates with the head line 4 of the arm cylinder 5 via the pilot signal control unit 21 only during the arm-in operation in which the arm regeneration valve 12 operates. The pilot signal line 17b communicates with the drain line 26 via the pilot signal control unit 21 when the main spool 1a is in neutral and when the arm is out, so that the unload valve 16 can operate and the arm regeneration valve 12 does not operate. Therefore, the unload valve 16 does not operate regardless of the head pressure of the arm cylinder 5.
[0063]
Therefore, the operating pressure of the unload valve 16 does not need to be set sufficiently higher than the head pressure of the arm cylinder 5 that can be generated at the time of arm-out operation as in the related art. Can be demonstrated. For this reason, the return oil control opening 15 of the main spool 1a can be reduced as much as necessary to sufficiently enhance the regeneration effect.
[0064]
That is, during the arm-in operation, the amount of oil discharged to the tank line 9 through the return oil control opening 15 is sufficiently reduced, and accordingly, the rod line 8 passes through the line 13, the check valve 14, and the arm regeneration valve 12. The amount of the regeneration oil regenerated in the head chamber 6 of the arm cylinder 5 can be increased, and a sufficient regeneration effect can be obtained.
[0065]
As described above, in the unload valve 16 of the regeneration circuit typified by the arm-in circuit of the hydraulic shovel, by applying the circuit according to the present invention, the unload valve 16 is prevented from operating during the arm-out operation. Thus, the operating pressure of the unload valve can be set to a value required to sufficiently enhance the regeneration effect. That is, it is possible to set the optimum unload valve operating pressure for the regeneration circuit of the arm-in circuit.
[0066]
The present invention is not limited to the regeneration circuit of the hydraulic circuit that controls the arm cylinder 5 of the excavator to arm-in, but can be applied to other regeneration circuits.
[0067]
For example, a regeneration circuit for regenerating hydraulic oil from a cylinder rod side to a cylinder head side is also provided in a bucket closing circuit that controls a bucket cylinder j so that a bucket g of the hydraulic shovel illustrated in FIG. Is provided, the present invention may be similarly applied to the regeneration circuit of the bucket close circuit.
[0068]
In short, the present invention can be widely applied to a machine having a regeneration circuit for regenerating hydraulic oil flowing out of one oil port of a hydraulic actuator such as a hydraulic cylinder to the other oil port.
[0069]
Further, providing the pilot signal control unit 21 integrally with the main spool of the control valve 1 or the regeneration spool of the arm regeneration valve 12 allows the pilot signal control unit 21 to be easily installed together with the control valve 1 or the arm regeneration valve 12 and Although there is an advantage that the pilot lines 2 and 11 for controlling the control valve 1 or the arm regeneration valve 12 can be shared, the pilot signal control unit 21 is not necessarily integrated with the main spool of the control valve 1 or the regeneration spool of the arm regeneration valve 12. It does not need to be provided.
[0070]
That is, the pilot signal control unit 21 is, for example, a control valve that can be switched together with the control valve 1 or the arm regeneration valve 12 by a pilot signal supplied to the arm extension operation pilot line 2 or the pilot line 11. A switching valve separate from the one or arm regeneration valve 12 may be used.
[0071]
【The invention's effect】
According to the first aspect of the present invention, the control valveHeadlineWhen the working fluid is supplied to theHeadlineSince the pilot signal line is connected to the unload valve from the control valve, the unload valve can be operated as before, andRod lineWhen the working fluid was supplied to the unload valve, the pilot signal control unit did not operate the unload valve.Rod lineWhen supplying working fluid toHeadlineThe operating pressure of the unload valve can be set to an optimum value for sufficiently enhancing the regeneration effect, regardless of the pressure generated in the unloading valve.
[0072]
According to the second aspect of the present invention, there is an advantage that the pilot signal control unit can be easily installed together with the regeneration valve.
[0073]
According to the third aspect of the present invention, there is an advantage that the pilot signal control unit can be easily installed together with the control valve.
[0074]
According to the fourth aspect of the present invention, in the regeneration circuit for regenerating the hydraulic oil from the rod line to the head line in the arm cylinder of the hydraulic shovel, the pilot signal control is performed during the arm-out operation for supplying the hydraulic oil to the rod line. Since the unloading valve is deactivated by the section, the operating pressure of the unloading valve that operates during arm-in operation that supplies hydraulic oil to the headline can be set to an optimal value to sufficiently enhance the regeneration effect .
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram showing one embodiment of a regeneration circuit according to the present invention.
FIG. 2 is a hydraulic circuit diagram showing another embodiment of the regeneration circuit according to the present invention.
FIG. 3 is a front view of the hydraulic excavator.
FIG. 4 is a hydraulic circuit diagram showing a conventional regeneration circuit.
[Explanation of symbols]
1 Control valve
4Headline
5 Arm cylinder as fluid pressure actuator
8Rod line
12 Regenerative valve
16 Unload valve
17a, 17b Pilot signal line
20 tanks
21 Pilot signal controller

Claims (4)

A control valve for controlling the direction of the working fluid;
A cylinder-type fluid pressure actuator operated by a working fluid through a control valve,
A head line and a rod line connecting the control valve and the fluid pressure actuator,
A regeneration valve that is provided between the head line and the rod line and operates only when the working fluid is supplied from the control valve to the head line , and regenerates the working fluid flowing out of the rod line from the fluid pressure actuator to the head line ,
An unload valve provided between the rod line and the tank and operated by an unload pilot signal;
A regenerative circuit, comprising: a pilot signal control unit for communicating an unloading pilot signal line disposed from the headline to the unloading valve when the regenerating valve is operated and cutting off when the regenerating valve is not operated. . The regeneration circuit according to claim 1, wherein the pilot signal control unit is provided integrally with the regeneration valve. The regeneration circuit according to claim 1, wherein the pilot signal control unit is provided integrally with the control valve. The regeneration circuit according to any one of claims 1 to 3, wherein the regeneration circuit is a hydraulic circuit that regenerates hydraulic oil from a rod line to a head line in an arm cylinder of a hydraulic shovel.

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