WO2003069164A1

WO2003069164A1 - Fluid pressure circuit

Info

Publication number: WO2003069164A1
Application number: PCT/JP2003/000037
Authority: WO
Inventors: Yoshiyuki Shimada
Original assignee: Shin Caterpillar Mitsubishi Ltd.
Priority date: 2002-02-12
Filing date: 2003-01-07
Publication date: 2003-08-21
Also published as: JP2003232303A

Abstract

A fluid pressure circuit, wherein a pilot pressure to a bucket spool (25) for controlling a bucket cylinder (19) is controllably reduced by a pressure reducing valve (36), the pressure reducing valve (36) is controlled by a control signal pressure branched from a pilot pressure to a boom first spool (21) for controlling a boom cylinder (15), the control signal pressure is controlled by a pressure reducing valve (38), and the pressure reducing valve (38) outputs the pilot pressure undisturbed to the pressure reducing valve (36) as a control signal pressure in a range where the pilot pressure of the boom first spool (21) is lower than a specified pressure and, in a range where the pilot pressure of the first boom spool (21) is higher than the specified pressure, outputs a control signal pressure reduced to a specified limit pressure to the pressure reducing valve (36) even if the pilot pressure is varied.

Description

Akira Fluid pressure circuit technology field

The present invention relates to a fluid pressure circuit having a pilot operated control valve.

Itoda

Background technology

As shown in FIG. 5, the hydraulic shovel as a construction machine is provided with a lower traveling body 11 equipped with a traveling motor, a rotating motor 12 of a rotating part 12 and a rotating motor. The upper turning body 13 is provided so as to be rotatable. The upper turning body 13 has the boom 14 of the front working machine and the boom cylinder 15 has the upper turning body 13. The boom 14 is supported by a stick 16 force S at the end of the boom 14 and is turned inward and outward by a stick cylinder 17. It is pivotally supported in the moving position, and the tip of the stick 16 is pivoted in the opening and closing directions by a bucket 18 force S and a bucket cylinder 19 at the tip of the stick 16. It is pivoted.

Here, the boom is raised by extending the boom cylinder 15, and the boom cylinder is extended by extending the stick cylinder 17. Utility model registration No. 2 579 95 in which each operation of bucket close can be obtained by extending the quinn and the socket cylinder 19 In the publication No. 87, a boom cylinder is installed on the left and right pump lines of the hydraulic shovel. The first control valve for the boom to be controlled and the second control valve for the boom, and the first control valve for the stick that controls the stick cylinder. A second stick control valve and a second stick control valve are provided, and the stick is adjusted in accordance with the boom lifting pilot pressure supplied to the boom first control valve. Shows the hydraulic circuit of the construction machine in which the stick's in-lot pressure supplied to the second control valve is controlled to be reduced by the pressure reducing valve. It is.

As shown in FIG. 6, the pressure reducing valve used in the hydraulic circuit of the construction machine disclosed in Japanese Utility Model Registration No. 25799587 is shown in FIG. Boom lift supplied to the boom 1st control valve The stick supplied to the stick 2nd control valve as the pipe pressure rises The quinn rod pressure is gradually reduced, and near the full lever operation position of the boom control valve, the boom lift pressure is reduced. When the set value is reached, the pressure reducing valve has the characteristic of reducing the stick-in-no-rot pressure to 0, so the second stick control valve is used. Returns to the neutral position, and as a result, the hydraulic oil supplied to the stick cylinder from the stick second control valve power The amount also as you to 0, minute its, it is assured hydraulic oil flow rate that will be supplied to the boom Shi Li down da through the boom first control valve.

As an application circuit using a pressure reducing valve having the characteristics shown in Fig. 6, for example, the interlocking operation of boom lifting and bucket close At times, high load The load is lower than that of the cylinder 15. The pump discharge oil easily flows to the cylinder 19, so the boom 14 goes up and is difficult to operate. In order to solve this problem, as shown in Fig. 7, install a pressure reducing valve in the nozzle and the イ -lot line as shown in Fig. 7. And good.

Referring to the hydraulic circuit shown in FIG. 7, the first boom 21 and the second boom that control the boom cylinder 15 are described. 2 Spool 2 2 and the stick that controls the stick cylinder 17 The first spool 23 and the stick 2nd spool And a bucket spool 25 for controlling the bucket cylinder 19.

The boom first spool 21, the stick second spool 24, and the bucket spool 25 are connected to one hydraulic pressure source 26, Hydraulic oil is supplied from this oil pressure source 26. — On the other hand, the boom second spool 22 and the stick first spool 23 are connected to the other hydraulic pressure source 27, and the hydraulic pressure source 27 is connected to the other hydraulic pressure source 27. Receives the supply of hydraulic oil. Each hydraulic pressure source 26, 27 supplies hydraulic oil to each spool via the respective parallel passage 28, and each spool is placed in the neutral position. At that time, they are connected to the tank 30 via the respective binos passages 29.

The boom lift-up nodal pressure action section of the first boom spool 21 and the neurot pressure action section of the second boom spool 22 include: The boom lift from the boom remote control valve 31 and the throttle lines 32 and 33 are connected respectively, and PT / JP03 / 00037

The socket closet opening of the socket spout control port is equipped with a bucket remote control valve. To close noise line 35 is connected.

Bucket Remote control valve 34 A block from the valve to the bucket closing nozzle of the socket spooner 25. In the close noise lot line 35, a pressure reducing valve 36 of an external port type is provided. In addition, the boom remote control valve 31 and the boom connected to the boom port 1 of the boom 1st spool 21 The boom-up signal pressure line 37 is branched from the up-noise mouth line 32, and this branched boom-up signal pressure line 3 7 is led to the signal pressure action section of the pressure reducing valve 36.

The pressure reducing valve 36 of the external nozzle type is provided with a boom remote control valve 31 and a boom lifter of the boom 1st spool 21. Lifting the boom that acts on the ilot pressure action part, and the bucket remote control valve according to the norobot pressure. The bucket close pilot pressure acting on the bucket close pilot operating part is reduced in pressure.

In other words, by operating the boom lift and the notch's close, the pressure reducing valve 36 is operated by the boom lift noise pressure, and By restricting the stroke of the socket spool 25, the amount of oil supplied to the boom cylinder 15 from the common oil pressure source 26 to ensure, boom 1 4 is you are in the jar by Ru on the force ^s. T JP03 / 00037

5 Like the stick cylinder control system in a two-pump circuit disclosed in Utility Model Registration No. 25799587, the left and right When the plane is equipped with the first stick 23 and the second stick 24, the boom-up operation is performed. In the linked operation of the stick-in operation and the stick-in operation, the stick-in pilot pressure is reduced by the boom-up noise pressure. Even if the pressure reducing valve (not shown in FIG. 7) is activated and the second spool 24 is returned to the neutral position, the stick is removed. Since hydraulic oil is supplied to the cylinder 17 from the hydraulic pressure source 27 through the first spool 23 of the stick, the stick cylinder 1 7 doesn't work The problem described in this publication, such as the boom-up operation and the bucket that rotates the bucket 18 toward the aircraft, does not cause such a problem. If it is applied to the linked operation of the close operation as it is, a problem will occur.

That is, in the hydraulic circuit shown in FIG. 7, when the boom raising operation and the bucket / close operation are interlocked, the operation shown in FIG. By the pressure reducing valve 36 with the characteristics shown in the figure, the boom lift-up nozzle of the boom 1st spool 21 from the boom remote control valve 31 As the boom lifting pilot pressure supplied to the pressure action section rises, the bucket spoon comes from the bucket remote control valve 34. The bucket-close pilot pressure supplied to the socket-close-pipe pressure-operating part of the nozzle 25 is gradually reduced. snow , It has the characteristic of reducing the bucket-close pilot pressure to zero near the full lever operation position of the pump remote control valve 31. .

However, the socket spool 25 is composed of the first and second booms 21 and 22 and the first and second booms. Since it is not composed of two parts like the punole 23 and stick No. 2 pool 24, it is composed of only one part. When the boom is lifted by the lever operation and the port pressure S increases, the bucket is operated by the pressure reducing valve 36 having the characteristics shown in FIG. To / from the socket 25 • Closed Norolet pressure S Once cut, only the bucket 25 is neutral. Bucket cylinder 19 will not move due to return to position, causing a problem

The problem is that not only the packet spool 25 but also the rotating motor control valve and the bucket that control the rotating motor can be mounted instead of the bucket. The same applies to a control valve that controls a workpiece such as a plate force.

The present invention has been made in view of such a point, and when a plurality of fluid pressure actuators are operated simultaneously, one fluid pressure actuator is operated. Reducing the pressure reducing valve to ensure the operation of the actuator may impair the operation of other fluid actuators. The purpose is to provide a fluid pressure circuit that can Uncovering the invention

The fluid pressure circuit of the present invention comprises one pipe-operated control valve for controlling one fluid pressure actuator and one fluid pressure actuator. Other pipe working type control valves that control other fluid pressure actuators that operate at the same time as the actuator, and one pilot operation A pilot signal supplied to another nozzle control valve by a control signal pressure branched from a pipe port pressure supplied to the valve control valve. And a pressure reducing valve that can control the pressure of the pilot valve, and when the pilot pressure supplied to one pilot operated control valve is higher than a certain pressure, the pressure of the pressure reducing valve is reduced. A fluid pressure circuit having pressure reducing valve control means for limiting a control function, wherein one fluid pressure actuator and another fluid pressure circuit are provided. When the actuator and the actuator are operated simultaneously, the pressure reducing valve supplies the pilot pressure to one of the pilot operated control valves preferentially. It is possible to ensure that one fluid pressure puck, which requires a sufficient fluid volume, can be operated, and that one nozzle-operated type can be operated. If the pilot pressure supplied to the control valve is higher than a certain pressure, the pressure reducing control function of the pressure reducing valve is limited by the pressure reducing valve control means, and other functions are performed. Since it is possible to supply the nozzle pressure to secure the opening area required for the neurot type operation control valve of this type, other fluid pressure valves can be supplied. The pressure-reducing valve control means in the fluid pressure circuit of the present invention, which can ensure the necessary operation of the heater stably, includes: In a range where the pilot pressure supplied to one pilot operated control valve is lower than a certain pressure, the control signal pressure is maintained without changing the pilot pressure. And a direct control characteristic section that outputs to the pressure reducing valve. The pilot pressure S supplied to the pilot-operated control valve S — in the range above the fixed pressure. It has a constant pressure control characteristic part for outputting a control signal pressure reduced to a constant V to pressure to the pressure reducing valve even if the pilot pressure changes. If the pilot pressure supplied to one of the pilot operated control valves is lower than a predetermined pressure, the direct control characteristic part of the pressure reducing valve control means causes the pressure reducing valve to have its original function. By exerting the decompression control function, one fluid pressure actuator can be reliably operated, and one nozzle-operated control valve. If the pressure at the nozzle port supplied to the pressure regulator is higher than a certain pressure, the pressure reduction control function of the pressure reducing valve is restricted by the constant pressure control characteristic part of the pressure reducing valve control means. The required operation of the fluid pressure actuator can be stably secured.

One pilot-operated control valve and another pilot-operated control valve in the fluid pressure circuit of the present invention supply working fluid from a common fluid pressure source. On the other hand, the other fluid pressure actuator is a fluid pressure circuit in which the one fluid pressure actuator is assumed to be a lighter load actuator. When operating one fluid pressure actuator and another fluid pressure actuator at the same time, the pressure reducing valve uses the working fluid supplied from the fluid pressure source. Other neurots JP03 / 00037

9 Supplied from a common fluid pressure source by suppressing the flow to other fluid load actuators with low load through the operable control valve. Since the working fluid is supplied to one fluid pressure actuator through one pipe-operated control valve, the load is low. The required operation can be ensured even with a high-load fluid pressure actuator that is installed in conjunction with the fluid pressure actuator described above.

One pipe-operated control valve in the fluid pressure circuit of the present invention is a control valve for controlling a boom cylinder of a hydraulic shovel. The other pilot operated control valve is a control valve that is installed in a one-to-one relationship with the other fluid pressure actuators of the hydraulic pressure level. The fluid pressure circuit is assumed to be a hydraulic fluid pressure circuit, and the hydraulic pressure boom cylinder and the other fluid pressure actuators are operated at the same time. When the pressure reducing valve is supplied, the boom cylinder needs a sufficient amount of oil by giving priority to the pipe port pressure to the control valve for the boom cylinder. The cylinder can be operated reliably, and the other pilot operated control valve can be used for other fluid pressure actuators. Even if the control valve is installed in a one-to-one relationship with the heater, since the pressure-reducing valve control means restricts the function of the pressure-reducing valve, other pilot valves are required. It is possible to supply the pilot pressure to secure the required opening area for the operable control valve, and the pressure reducing valve stops other fluid pressure actuators. And can be prevented. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a circuit diagram showing an embodiment of a fluid pressure circuit according to the present invention. FIG. 2 is a circuit diagram showing a pressure reducing valve control means used in the fluid pressure circuit. FIG. 3 is a characteristic diagram showing the control characteristics of the pressure reducing valve, and FIG. 3 is a characteristic diagram showing the pressure reducing characteristics of the pressure reducing valve used alone in the fluid pressure circuit, and FIG. FIG. 5 is a characteristic diagram showing a combination characteristic of a valve control means and a pressure reducing valve. FIG. 5 is a side view of a hydraulic shovel, and FIG. 6 is a diagram showing a conventional hydraulic circuit. Fig. 7 is a characteristic diagram showing the pressure-reducing characteristics of the stick-in port pressure with respect to the boom-up port pressure of the pressure-reducing valve, and Fig. 7 shows the assumptions of the present invention. A hydraulic circuit using a pressure reducing valve in the bucket nozzle outlet line is shown. is there . BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail with reference to one embodiment shown in FIGS. 1 to 4. FIG. Fig. 1 shows a hydraulic circuit as a hydraulic circuit installed on a hydraulic shovel as a construction machine. The same parts as those in the hydraulic shovel shown in FIG. 5 are denoted by the same reference numerals.

As shown in FIG. 1, this hydraulic circuit is one of the pipes that controls the boom cylinder 15 as one of the fluid pressure actuators. Boo as a port-operated control valve PT / JP03 / 00037

And the non-first scan Phu Norre 21 your good beauty boom second scan pool 2 ^2, vinegar te I click Shi Li down da 17 a control to Ru scan tape click the first scan pool 23 And a second spool 24 for the stick and another pipe for controlling the bucket cylinder 19 as another fluid pressure actuator. It is equipped with a socket spool 25 as a lot-operated control valve.

These boom first spool 21, boom second spool 22, stick first spool 23, stick second spool 24, etc. The bucket spool 25 is a pipe-operated center bin. It is a snorve.

The first spool 21 of the boom, the second spool 24 of the stick, and the bucket spool 25 are one of the common fluid pressure sources. The hydraulic pressure source 26 is connected to the hydraulic pressure source 26 and receives a supply of hydraulic oil as a working fluid from the hydraulic pressure source 26.

On the other hand, boom second pool 22 and stick

The one spool 23 is connected to the other hydraulic pressure source 27 and receives the supply of hydraulic oil from this hydraulic pressure source 27.

Each hydraulic pressure source 26, 27 supplies hydraulic oil to each spool via the respective parallel passage 28, and when each spool is in the neutral position. In this case, each tank is connected to a tank 30 via a respective bypass passage 29.

The bucket cylinder 19 that rotates the bracket is lower in load than the high-load boom cylinder 15 that supports the load of the entire front work machine. The socket spool 25 that controls the socket cylinder 19 is an actuator. This is a control valve installed in a one-to-one relationship with the socket cylinder 19.

Boom uppipe for boom 1st spoonhole 21 and pressure section for boom and 2nd spoon 22 boom. The boom remote control valve 31 serving as a boom operating valve is provided with a boom lifting pipe line 32, 33 in the port pressure operating section. Each of them is connected to the bucket-closing pilot pressure acting portion of the bucket spool 25, and the bucket as a bucket operation valve is provided. A bucket close lot line 35 from the tri-mo valve 34 is connected.

The boom lowering port of the first boom 1 spool 21 has a boom lowering knob with a boom remote control valve 31. A train (not shown) is connected, and the bucket open-pipe port pressure operation section of the bucket spool 25 has a bucket tree. The socket open-no-rot line (not shown) of the motor valve 3-4 is connected, and the first spool 23 of the stick is connected. Stick ^2nd pool 24 stick stick pipe outlet In the pressure application section, there are a stick operating valve (not shown) and a stick-in-pilot line (not shown). K. Outno Lock door La Lee emissions (not Shimese the figure) is connected.

In the boom remote control valve 31, the operation in the direction of the arrow shown in FIG. 1 is a boom raising operation, and the bucket remote control , w,,. PCT / JP03 / 00037

For the 13-way valve 34, the operation in the direction of the arrow is a socket-close operation.

Bucket remote control valve 3 4 force, bucket closer 25 bucket close / bucket reaching to the pressure action section · Inside the close pilot line 35, a pressure reducing valve 36 of an external pipe type is provided.

In addition, the boom remote control valve 31 is connected to the boom lift port of the first boom 1 spool 21 and the boom lift pie port connected to the pressure action section. The boom-up signal pressure line 37 is branched from the train 32, and the branched boom-up signal pressure line 37 is used as pressure reducing valve control means. The control signal pressure line 39 connected to the primary side of all the pressure reducing valves 38 and drawn out from the secondary side of the pressure reducing valve 38 controls the control signal pressure of the pressure reducing valve 36. It is connected to the working part.

This pressure reducing valve 38 has characteristics as shown in FIG. In FIG. 2, the abscissa represents the primary-side boom up-nozzle pressure input to the pressure reducing valve 38, and the ordinate represents the pressure reducing valve 38. The control signal pressure to the controlled secondary pressure, that is, the pressure reducing valve 36 is shown, and the boom is raised. Even if the pilot pressure becomes higher than the pilot pressure SPa, the control signal pressure does not become higher than Pa.

That is, the pressure reducing valve 38 is connected to the boom upper spool 21 when the boom upper nozzle pressure supplied to the boom first spool 21 is lower than a predetermined pressure. A direct control function that outputs the pressure from the pilot port to the pressure reducing valve 36 as it is as a control signal pressure 00037

In addition to having the sex part 38a, the boom lift pipe pressure supplied to the boom first spool 21 is higher than a certain pressure. Even if the boom lifting pipe pressure changes, a control signal pressure reduced to a constant limit pressure is output to the pressure reducing valve 36 even if the pressure changes. And functions as a limiter for the external pilot control signal of the pressure reducing valve 36.

The pressure reducing valve 36 in the socket close pilot line 35 is connected to a boom-up signal pressure line 37 as shown in FIG. In response to the control signal pressure output from the pressure reducing valve 38, the bucket remote control valve 34, the bucket of the socket spool 25, and the like. It controls the bucket close noise pressure supplied to the loose pipe mouth pressure acting part by reducing the pressure.

Therefore, the combination of the pressure reducing valve 36 and the pressure reducing valve 38 is, as shown in FIG. Even if the pilot pressure rises above a certain pressure Pa near the full lever operation position of the boom remote control valve 31, the nozzle of the socket spool 25 does not G. Close. The socket-closed nozzle pressure supplied to the pilot-pressure operating section is required to operate the socket cylinder 19. The bucket close pie port pressure Pb, which can secure a certain opening area of the socket spool, is kept from being lower than the pressure Pb.

That is, the characteristics of the pressure reducing valve 36 shown in FIG. 03 00037

15 The level of the opening area of the packet spool 25 required to operate the socket cylinder 19 is secured. If the noise noise pressure is Pb and the control signal pressure of the pressure reducing valve 36 at that time is Pa, then the boom raising pilot pressure exceeds Pa. Nevertheless, as shown in FIG. 2, the control signal pressure from the pressure reducing valve 38 to the pressure reducing valve 36 does not become higher than Pa as shown in FIG. As shown in the figure, the secondary close pressure of the pressure reducing valve 36, ie, the socket close pilot pressure, must not fall below Pb. Yes.

Next, the operation and effect of this embodiment will be described.

When the boom remote control valve 31 of the hydraulic pressure shovel is operated to the boom raising side, the bucket remote control valve 34 is simultaneously bucketed. Operate the close side to extend the boom cylinder 15 and the bucket cylinder 19 at the same time, and move the hydraulic shovel over the boom. When performing the socket close operation while operating the boom, the boom that has been branched from the boom-up nozzle line 32 The boom lifting port pressure acts on the pressure reducing valve 38 by the rising signal pressure line 37, and the pressure reducing valve 38 controls the characteristics shown in FIG. Outputs signal pressure.

In the characteristic shown in FIG. 2, in the direct control characteristic section 38a, the pressure reducing valve 38 is connected to the boom lift pipe from the boom remote control valve 31. Since the lot pressure is output to the control signal pressure action section of the pressure reducing valve 36 as it is as the control signal pressure, the packet remote control valve 34 Through the pressure reducing valve 36 The bucket close / pilot pressure supplied to the bucket / close / pull pressure operating section of pool 25 is shown in Fig. 4. As shown, the decompression characteristics of FIG. 3 remain as they are.

Me other child, Bas Ke Tsu door scan-flops over Norre 2 5 of the scan-flops one / Les opening of force ^s Noge Tsu door re-mode co-down valve 3 4 Do we commanded opening degree by Ri small Ku system The hydraulic fluid supplied from the pump power of the hydraulic pressure source 26 to the bucket cylinder 19 is boosted by the bucket spool 25. Since it is throttled in accordance with the pipe lifting pressure, a large amount of flow is not supplied to the bucket cylinder 19 with a low load. It is also possible that only the bucket cylinder 19 operates at high speed and closes the bucket.

In other words, the pressure at the pipe outlet is given priority to the boom 1st spoonhole 21 from the bucket spool 25 by the pressure reducing valve 36. By supplying the hydraulic fluid, the hydraulic fluid supplied from the common hydraulic pressure source ²⁶ passes through the first spool 21 of the boom and passes through the bucket cylinder 19. For a heavy-load boom cylinder 15 that has a large capacity and requires a sufficient amount of hydraulic oil, and also supports the load of the entire front work machine. As a result, the required amount of hydraulic oil can be reliably supplied.

In short, even in a hydraulic circuit in which a low-load bucket cylinder 19 and a high-load boom cylinder 15 are installed, The reliable movement of the boom by the cylinder 15 and the bucket-close operation by the bucket cylinder 19 are balanced. It can be implemented smoothly and smoothly, and necessary operations can be performed. PT / JP03 / 00037

17 can be secured.

On the other hand, operate the boom remote control valve 31 toward the boom upper side to the vicinity of the hood lever operation position to make the boom 1st spoiler 21 and boom When the second spoonhole 22 is operated up to the vicinity of the hood stroke, the boom cylinder 15 is moved up to the maximum hydraulic oil flow. It is possible to operate it.

At this time, even if the boom lift pilot pressure from the boom remote control valve 31 increases, the constant pressure control characteristic section 38b shown in FIG. After the functioning pressure reducing valve 38, the control signal pressure limited to a certain limit pressure acts on the control signal pressure action section of the pressure reducing valve 36, so that the valve is controlled. Supplied from the socket remote control valve 34 through the pressure reducing valve 36 to the bucket close pilot pressure action section of the bucket spool 25. The packet close pilot pressure does not drop below a certain pressure Pb as shown in FIG.

In this case, the close noise pressure Pb is necessary for operating the / ket cylinder 19 to perform the close / close operation. It is a pilot pressure that can secure a certain fixed bucket spool opening area.

The bucket spool 25 is provided in a one-to-one relationship with the bucket cylinder 19, and the bucket clone 25 is provided.ズ The pressure reducing valve is

The bucket cylinder 19 is used for the bucket close from the pressure reducing valve 36 whose pressure is regulated by the constant pressure control characteristic section 38 b of 38. The minimum packet / close noise pressure Pb required for operation can be supplied, so the required packet / cloth is required. Can be ensured stably.

As described above, the pressure reducing valve 36 having the pressure reducing characteristics as shown in FIG. 3 is assembled in the socket 'close pilot line 35'. In addition, the pressure of the pressure reducing valve 36 is controlled by the outlet pressure of the boom to the first spool 21 of the boom, and the bucket is controlled by the bucket. The bucket closes to the tray spout No. 25 Even if the interlocking operation such as controlling the pressure to reduce the pressure of the bucket is performed, Since the above-described pressure reducing valve 38 having the characteristics shown in FIG. 2 is incorporated in the signal pressure line 37, the control signal pressure to the pressure reducing valve 36 is shown in FIG. As the pressure is not more than Pa, even if the boom-up and full-reno operation increases the boom-up pipe opening pressure, the 4 As shown in the figure In addition, the bucket close / eject pressure to the bucket spool 25 is required to operate the bucket cylinder 19. Since the bucket close pressure is lower than the bucket close-out pressure Pb that can secure a certain fixed bucket spool opening area, As before, the bucket is connected to the bucket spout 25 by the pressure reducing valve 36. The closing pipe pressure is completely cut off. The bucket spool 25 does not return to the neutral position, and the bucket cylinder 19 power S power does not disappear. o

Note that, in the illustrated embodiment, the boom lift and As described in the case of the socket close, similarly, the swivel motor control that is controlled by a single spool is used. If the same pressure reducing valve 36 is used for the pilot line of the spool that controls other actuators such as By installing a pressure reducing valve 38 as shown in Fig. 2 on the control signal pressure line 39 of the pressure reducing valve 36, similar effects can be expected. it can . Possibility of industrial use

The main fluid pressure circuit operates not only construction machines such as hydraulic shovels, but also, if necessary, a plurality of fluid pressure actuators at the same time. In this case, the pressure reducing valve to ensure the operation of one fluid pressure actuator will impair the operation of the other fluid pressure actuator. In such cases, it can be widely applied to solve the problem.

Claims

Range of request

1. A pipe-operated control valve for controlling the hydraulic actuator of the present invention;

One fluid pressure actuator and other language operated at the same time

Other nozzle-operated control valves for controlling the fluid pressure actuator, and

One pipe outlet is supplied to the operable control valve. The control signal pressure branched from the port pressure force can reduce the neurot pressure supplied to the other port-operated control valves. Pressure reducing valve and,

-The pressure reducing valve control restricts the pressure reducing control function of the pressure reducing valve when the pressure supplied to the port operated control valve is higher than a certain pressure. Means and

A fluid pressure circuit characterized by having:

2. The pressure reducing valve control means

If the pilot port pressure supplied to one of the nozzle-operated control valves is lower than a certain pressure, the pilot port pressure is kept at the same level. A direct control characteristic part which outputs to the pressure reducing valve as a signal pressure;

If the pilot pressure supplied to the pilot-operated control valve is higher than a certain pressure, the pilot pressure will not change even if the pilot pressure changes. A constant-pressure control characteristic section that outputs a control signal pressure reduced to a constant limit pressure to a pressure-reducing valve;

The scope of the claim characterized by having On-board fluid pressure circuit.

3. One of the nozzle-operated control valves and the other of the pipe-operated control valves receive working fluid from a common fluid pressure source.

The other fluid actuator is a fluid actuator that is lower in load than the other fluid actuator.

The fluid pressure circuit according to claim 1 or claim 2, characterized by this.

4. The first pilot operated control valve is a control valve that controls the boom cylinder of the hydraulic shovel,

Other pilot operated control valves are control valves that are installed in a one-to-one relationship with other hydraulic actuators on the hydraulic shovel.

The fluid pressure circuit according to any one of claims 1 to 3, characterized by this.