JP4993363B2 - Fluid control circuit and work machine - Google Patents

Description

  The present invention relates to a fluid control circuit including a tool actuator and another actuator, and a work machine equipped with the fluid control circuit.

  In a work machine equipped with a tool instead of a bucket in the front working device of a hydraulic excavator, the spool of the control valve is controlled according to the amount of tool lever operation, and the amount of oil supplied from the pump to the tool actuator is controlled. In some cases, when the flow rate of the actuator is set, the upper limit of the flow rate output from the pump becomes the set flow rate of the tool actuator.

  Since the tool lever operation amount vs. spool opening characteristics are 1: 1, the tool pressure is lower than the boom raising pressure when the tool actuator and other actuators with higher operating pressure than the tool actuator such as boom raising are operated in conjunction. Most of the oil flowing from the pump flows into the tool actuator, making it difficult for the boom to rise, and sufficient interlocking operability cannot be obtained. Further, when the tool actuator is operated during the boom raising operation, the boom is suddenly decelerated, so that a shock is also generated.

  Also, when the tool actuator flow rate is set, the upper limit value of the flow rate output by the pump is the tool actuator set flow rate. Since only the flow rate required for the actuator is output, the pump capacity cannot be fully exhibited and sufficient interlocking operability cannot be obtained.

  On the other hand, there is a fluid pressure circuit control device that improves the interlocking operability when interlocking a plurality of fluid pressure actuators (see, for example, Patent Document 1).

This is because an electromagnetic bypass throttling variable adjustment valve that is switched by an electric signal from the controller is provided on the center bypass line between the electromagnetic attachment switching valve and the negative control relief valve. A pump pressure sensor and a load pressure sensor are provided on each line on the output side of the spool for the attachment and the spool for the attachment, respectively, and the controller controls the stroke of the spool for the arm and the spool for the attachment so that each of the P-C The variable throttle area is controlled, and the bypass throttle variable adjustment valve is controlled to correct the combined value of the bypass variable throttle areas in the spool stroke so that an appropriate pump signal pressure can be obtained.
Japanese Patent Laying-Open No. 2006-144851 (first page, FIG. 1)

  Such a fluid pressure circuit requires a bypass throttle variable adjustment valve on the center bypass line, a pump pressure sensor on the pump line, a load pressure sensor on each output line, and the circuit configuration of the fluid pressure circuit and its control device is It becomes complicated.

  The present invention has been made in view of the above points, and an object thereof is to provide a fluid control circuit and a work machine that can improve the interlocking operability between a tool actuator and other actuators with a simple circuit configuration. And

The invention described in claim 1 includes a bypass passage for bypassing the working fluid from the upstream side to the downstream side in the neutral position, and outputting the working fluid discharged from the pump according to the amount of tool operation. A control valve, a tool control valve that supplies the working fluid output from the tool bypass control valve to the tool actuator according to the amount of tool operation, and a bypass passage that bypasses the working fluid from upstream to downstream in the neutral position Other control valves that are provided inside and that supply the working fluid discharged from the pump to other actuators according to other operation amounts, tool operation amounts and tool bypass control valves according to other operation amounts, etc. And a control means for outputting a control signal for controlling the control valve and the tool control valve. The control means includes a single-acting table with a characteristic that controls the tool bypass control valve so that the tool bypass control valve makes the maximum stroke at the maximum operation amount when the tool is operated alone, and the tool In conjunction with the actuator and other actuators, it has a characteristic interlocking table that controls the control signal to the tool bypass control valve with respect to the tool operation amount so that it is narrowed down with the maximum operation amount than when the tool is operated alone , When operating the tool operation amount up to 100% during the independent operation of other actuators, increase the command value to the tool bypass control valve to a predetermined value and change the tool operation amount from 100% to the other actuator. Commanded to the tool bypass control valve. A fluid control circuit having a function of lowering the hysteresis component with the tool bypass control valve than the predetermined value.

  According to a second aspect of the present invention, the pump in the fluid control circuit according to the first aspect is a variable displacement pump, and the negative control pressure generated through the bypass passages in the tool bypass control valve and other control valves. A regulator that controls the pump capacity to a greater value as the tool size is smaller is limited, and the control means controls the regulator so that the regulator can output the maximum flow rate during linked operation by limiting the regulator with the required flow rate of the tool according to the amount of tool operation. It has a function to do.

  The invention described in claim 3 includes an airframe, a boom mounted on the airframe so as to be movable up and down, a tool provided on the boom via an arm, a tool actuator for operating the tool, and a boom that moves up and down the boom. And a fluid control circuit according to claim 1 provided for a tool actuator and a boom actuator of the work device, wherein the fluid control circuit is mounted on the airframe together with a pump. It is a working machine provided with a tank for storing working fluid.

According to the first aspect of the present invention, when the tool is operated alone, the tool bypass control valve is controlled by the single operation table of the control means so that the control signal to the tool bypass control valve with respect to the tool operation amount is the maximum operation amount. Since the maximum stroke can be achieved, a sufficient operating flow rate can be supplied to a single-operated tool actuator, and when the tool actuator and other actuators are linked, the control table linked to the tool operation amount Since the control signal to the tool bypass control valve is throttled at the maximum operating amount compared with the single tool operation, it is possible to prevent the working fluid from flowing only into the tool actuator with a low operating pressure. Switch operability from single-acting table to interlocking table That can be improved with a simple circuit configuration. Furthermore, the control means controls the tool command value when the other actuator is operated in an interlocked manner from the single operation of the tool smaller than the tool command value when the tool is operated in an interlocked manner during the independent operation of the other actuator, The influence of the hysteresis of the tool bypass control valve can be reduced.

  According to the second aspect of the present invention, the control means restricts the regulator with the required flow rate of the tool according to the amount of tool operation when the tool is operated alone, but the regulator of the variable displacement pump is set to the maximum flow rate during the interlock operation. Can control the output of the variable displacement pump without restricting the flow rate of the pump, and the interlocking operability between the tool actuator and other actuators can be improved with a sufficient pump flow rate. be able to.

  According to the third aspect of the invention, the interlocking operability between the tool actuator and the boom actuator can be improved with a fluid control circuit having a simple circuit configuration, and the boom raising operation can be performed while operating the tool. It is possible to provide a working machine that can smoothly move

  Hereinafter, the present invention will be described in detail with reference to one embodiment shown in FIGS.

  FIG. 4 shows a work machine A according to the present invention, in which a lower traveling body 1 having a traveling motor 1m as a fluid pressure actuator on the left and right sides is connected to a swing motor 3m as a fluid pressure actuator via a swing bearing portion 2. The upper revolving unit 3 that can be swiveled is provided, and the power unit 4 and the cab 5 are mounted on the upper revolving unit 3 to constitute the airframe B.

  The working device 6 is mounted on the machine body B. In the working device 6, the base end of the boom 7 is pivotally supported on the upper swing body 3 so as to be rotatable in the vertical direction, and an arm 8 is pivotally supported on the distal end of the boom 7. The tool 9 is pivotally supported in place of the bucket, the boom 7 is rotated in the vertical direction by the boom actuator 7a, that is, moved up and down, the arm 8 is rotated by the arm actuator 8a, and the tool 9 is It is actuated by the tool actuator 9a and rotated by the bucket actuator 9b.

  FIG. 1 shows a fluid control circuit 10 which is mounted on a work machine A and has a feature in a boom / tool interlocking circuit. In the fluid control circuit 10, the working fluid is oil using hydraulic fluid, and the fluid pressure is hydraulic.

  In the fluid control circuit 10 shown in FIG. 1, a discharge line 12 of a variable displacement pump 11 as a pump is provided with a center bypass line 13 and a hydraulic oil supply line 15 through a travel straight valve 14. A tool bypass control valve 16 and a boom control valve 17 as another control valve are connected to the center bypass line 13 and the hydraulic oil supply line 15, respectively.

  The tool bypass control valve 16 internally includes a bypass passage 16b that bypasses hydraulic oil from the upstream side to the downstream side in the neutral position, and operates the hydraulic oil discharged from the variable displacement pump 11 in the non-neutral position by operating the tool lever. It is a spool valve that outputs according to the amount.

  The boom control valve 17 is internally provided with a bypass passage 17b for bypassing the hydraulic oil from the upstream side to the downstream side in the neutral position, and in the non-neutral position, the hydraulic oil discharged from the variable displacement pump 11 is operated for other operations. This is a spool valve that is supplied to a boom actuator 7a as another actuator in accordance with a boom lever operation amount as a quantity.

  The hydraulic oil can also be supplied to the cylinder head side of the boom actuator 7a from a second boom control valve (not shown).

  The output line 21 from the tool bypass control valve 16 is connected to the input port of the tool control valve 22. This tool control valve 22 uses the hydraulic oil output from the tool bypass control valve 16 according to the amount of tool lever operation. And a function of supplying to the tool actuator 9a.

  The downstream portion of the center bypass line 13 is connected to a hydraulic oil storage tank 25 via a pressure setting valve, that is, a relief valve 23 and a throttle 24, and a negative control line 26 is branched immediately before the relief valve 23 and the throttle 24, A check valve 27 is connected to a regulator 29 that controls the swash plate 28 of the variable displacement pump 11.

  The variable displacement pump 11 is mounted on the upper swing body 3 of the airframe B together with an engine (not shown) and driven by the engine, and the tank 25 is mounted in the vicinity of the pump on the upper swing body 3 and has a pump suction port. Supply hydraulic oil to

  The negative control pressure of the negative control line 26 acting on the regulator 29 varies depending on the spool stroke amounts of the tool bypass control valve 16 and the boom control valve 17.

  That is, the larger the spool stroke amount of the tool bypass control valve 16 and the boom control valve 17, the smaller the negative control pressure generated through the bypass passages 16b and 17b in these valves, and the smaller this negative control pressure is. The regulator 29 greatly controls the pump capacity.

  Conversely, the smaller the spool stroke amount of the tool bypass control valve 16 and the boom control valve 17, the closer to the neutral position, the greater the negative control pressure generated through each bypass passage 16b, 17b in these valves, The greater the negative control pressure, the smaller the regulator 29 controls the pump capacity.

  A tool lever 31 for operating the tool actuator 9a and a boom lever 32 for operating the boom actuator 7a are connected to the input portion of the control means 33, and the tool bypass control valve 16 and the boom are connected to the output portion of the control means 33. A control valve 17, a tool control valve 22, and a regulator 29 are connected.

  This control means 33 outputs a control signal for controlling the tool bypass control valve 16, the boom control valve 17 and the tool control valve 22 in accordance with the tool lever operation amount and the boom lever operation amount. In addition to a so-called controller having a storage circuit for storing a data table or the like, an electro-hydraulic conversion valve (not shown) such as an electromagnetic proportional valve for converting an electrical signal into a pilot pressure signal at the final output if necessary It has.

  When the tool is operated alone, the control means 33 causes the tool bypass control valve 16 to make the maximum stroke with the control signal (electrical signal or pilot pressure signal) to the tool bypass control valve 16 with respect to the tool lever operation amount with the maximum operation amount. And a control signal (electrical signal or pilot) to the tool bypass control valve 16 with respect to the amount of tool lever operation when the tool actuator 9a and the boom actuator 7a are operated in conjunction with each other. Pressure signal) is provided with an interlocking table 35 having a characteristic for controlling the maximum operation amount to be reduced from that during single tool operation, and a selection unit 36 for selecting either the single acting table 34 or the interlocking table 35. is doing.

  The control means 33 includes a tool lever operation amount / flow rate characteristic determination unit 37 that determines the relationship between the tool lever operation amount that operates the tool actuator 9a in one direction and the flow rate, and a flow rate that determines the relationship between the flow rate and pressure. And a pressure characteristic determination unit 38. Furthermore, although it has a tool lever operation amount / flow rate characteristic and a flow rate / pressure characteristic for operating the tool actuator 9a in the other direction, the illustration is omitted.

  The control means 33 includes a boom raising characteristic determining unit 39 that determines the relationship between the boom lever operation amount and the boom raising control signal (electrical signal or pilot pressure signal) to the boom control valve 17, and the relationship between the boom lowering control signal. And a boom lowering characteristic determining unit (not shown).

  The control means 33 includes a flow rate limiting function that restricts the regulator 29 with the required flow rate of the tool according to the tool lever operation amount obtained from the tool lever operation amount / flow rate characteristic determination unit 37 when the tool is operated alone, and a regulator during the interlock operation. 29 is provided with a function for controlling 29 so that the maximum flow rate set by the maximum flow rate setting device 41 can be output, and a selection unit 42 for selecting one of these functions. The maximum flow rate setting device 41 can release the flow rate limiting function by the tool lever operation amount / flow rate characteristic determining unit 37 and cause the variable displacement pump 11 to discharge the maximum flow rate.

  Next, the operation of the embodiment shown in FIG. 1 will be described with reference to the flowchart shown in FIG.

(Step S1)
The single-acting table 34 and the interlocking table 35 provide two types of tool lever operation amount vs. spool opening characteristics to determine whether the tool lever is operated alone or when the tool lever / boom lever is interlocked.

(Step S2)
When the tool is operated alone, the selection unit 36 selects the single-acting table 34 in which the spool makes the maximum stroke by operating the full lever.

(Step S3)
When this tool is operated alone, the tool lever operation amount / flow rate characteristic determination unit 37 is selected by the selection unit 42 so that the flow rate output from the variable displacement pump 11 is limited by the required flow rate of the tool and only the required flow rate is discharged Let

(Step S4)
When operating the tool lever / boom lever interlocking operation with the same pump with which the pump flow rate is determined, by selecting the interlocking table 35 using the selection unit 36, the spool stroke of the tool bypass control valve 16 can be reduced compared to when operating alone. Since the flow rate supplied to the tool actuator 9a via the tool control valve 22 is limited, the necessary flow rate can be supplied to the high-load boom actuator 7a, and the boom raising operation can be secured.

(Step S5)
At the time of interlock operation with this same pump, the maximum flow rate setter 41 is selected by the selection unit 42 so that the maximum flow rate that can be output by the variable displacement pump 11 is set to the maximum flow rate of the maximum flow rate setter 41 The flow rate is not restricted by the tool lever operation amount / flow rate characteristic determination unit 37

  Next, FIG. 3 considers the hysteresis of the tool bypass control valve 16, and when the tool single action is changed to the tool / boom linkage, the command value is made smaller than the command value when the boom single action is changed to the tool / boom linkage. A control example is shown.

(Step S6)
Judge whether the tool single-action is linked to the tool / boom or the boom single-action is linked to the tool / boom.

(Step S7)
For example, when operating the tool lever 31 to 100% during the boom lever operation, the command value of the tool bypass control valve 16 is increased from 0 to XkPa.

(Step S8)
On the other hand, when the boom lever 32 is operated with the tool lever 31 operated 100%, the command value of the tool bypass control valve 16 is reduced from, for example, 4000 kPa to (X−α) kPa. When the command value of the tool bypass control valve 16 is lowered, the influence of hysteresis is reduced by making α kPa lower than when raising the step S7.

  Next, the effect of this embodiment will be described.

  When operating the tool alone, the tool bypass control valve 16 can be stroked at the maximum operation amount by the control signal to the tool bypass control valve 16 with respect to the tool operation amount by the single action table 34 of the control means 33. A sufficient operating flow rate can be supplied to the tool actuator 9a for single operation.

  On the other hand, during the interlock operation of the tool actuator 9a and the boom actuator 7a, the control signal to the tool bypass control valve 16 with respect to the tool operation amount is the maximum operation amount according to the interlock table 35 of the control means 33. Since the working fluid can be prevented from flowing into only the tool actuator 9a having a low operating pressure because it is further throttled, and the conventional bypass throttle variable adjustment valve, pump pressure sensor and load pressure sensor are not required, the tool actuator 9a And the boom actuator 7a can be improved with a simple circuit configuration in which the single-acting table 34 is switched to the interlocking table 35.

  That is, when the tool actuator 9a and the boom actuator 7a are interlocked, the flow rate flowing to the lightly loaded tool actuator 9a is throttled by the interlocking table 35, so that the necessary amount of oil is also supplied to the heavy load boom actuator 7a. Will be able to. Furthermore, even if the tool actuator 9a is inserted during the boom raising operation of the heavy load boom actuator 7a, the flow rate that flows into the tool actuator 9a is only the minimum required flow rate to the tool actuator 9a. The balance can be adjusted and it can be adjusted to smooth movement.

  The control means 33 controls the regulator 29 with the required flow rate of the tool according to the amount of tool operation when operating the tool alone, but controls the regulator 29 of the variable displacement pump 11 so that it can output up to the maximum flow rate when operating in conjunction. Therefore, the capacity of the variable displacement pump 11 can be fully demonstrated without restricting the flow rate of the variable displacement pump 11, and the interlocking operability between the tool actuator 9a and the boom actuator 7a is improved with sufficient pump flow rate. Can be made.

  The interlocking operability between the tool actuator 9a and the boom actuator 7a can be improved by the fluid control circuit 10 having a simple circuit configuration, and the boom 7 can be raised smoothly while operating the tool 9. Work machine A can be provided.

  When the tool bypass control valve 16, the boom control valve 17 and the tool control valve 22 are electromagnetic valves, the electrical signal output from the arithmetic circuit of the control means 33 may be directly input. In the case of an operation type valve, the electric signal output from the arithmetic circuit of the control means 33 may be converted into a pilot pressure by an electromagnetic proportional valve (not shown) and applied to each pilot operation type valve.

  The present invention is applicable not only to a mobile work machine A such as a hydraulic excavator but also to a stationary work machine and a hydraulic control circuit for controlling the hydraulic pressure thereof.

It is a circuit diagram showing one embodiment of a fluid control circuit concerning the present invention. It is a flowchart which shows the example of control of a fluid control circuit same as the above. It is a flowchart which shows the example of determination of the command value for tools of a fluid control circuit same as the above. It is a side view of the working machine which concerns on this invention.

Explanation of symbols

A Work machine B Airframe 6 Work device 7 Boom
7a Boom actuator as another actuator 8 Arm 9 Tool
9a Tool actuator
10 Fluid control circuit
11 Variable displacement pump as pump
16 Bypass control valve for tools
16b Bypass passage
17 Boom control valve as other control valve
17b Bypass passage
22 Tool control valve
25 tanks
29 Regulator
33 Control means
34 Single acting table
35 Interlocking table

Claims (3)

A bypass control valve for a tool that internally includes a bypass passage that bypasses the working fluid from the upstream side to the downstream side in a neutral position and outputs the working fluid discharged from the pump according to the amount of tool operation;
A tool control valve that supplies the working fluid output from the tool bypass control valve to the tool actuator according to the amount of tool operation;
Another control valve that internally includes a bypass passage that bypasses the working fluid from the upstream side to the downstream side in a neutral position and supplies the working fluid discharged from the pump to other actuators according to other operation amounts;
A tool bypass control valve according to a tool operation amount and another operation amount, a control means for outputting a control signal for controlling the other control valve and the tool control valve, and
The control means
A single-acting table with characteristics that control the control signal to the tool bypass control valve for the tool operation amount so that the tool bypass control valve makes the maximum stroke at the maximum operation amount when the tool is operated alone,
When synchronous operation of the actuator and another actuator for the tool; and a linkage table of characteristic be controlled to the control signal to the tool bypass control valve for tool operation amount, squeezing from time tools alone operation at the maximum operation amount With
When operating the tool operation amount up to 100% during the independent operation of other actuators, increase the command value to the tool bypass control valve to a predetermined value and change the tool operation amount from 100% to the other actuator. A fluid control circuit having a function of lowering the command value to the tool bypass control valve by the hysteresis of the tool bypass control valve from the predetermined value when the two are operated in conjunction with each other. The pump is a variable displacement pump,
It has a regulator that controls the pump capacity larger as the negative control pressure generated through the bypass passages in the tool bypass control valve and other control valves is smaller,
The control means
The fluid control according to claim 1, wherein the regulator is limited to a flow rate required by the tool according to the amount of tool operation when the tool is operated alone, and the regulator is controlled so that the regulator can output up to the maximum flow rate during the interlock operation. circuit. The aircraft,
A boom mounted on the fuselage so as to be movable up and down, a tool provided on the boom via an arm, a tool actuator for operating the tool, and a working device including a boom actuator for moving the boom up and down;
The fluid control circuit according to claim 1 or 2 provided for a tool actuator and a boom actuator of a work device,
The fluid control circuit includes a working fluid storage tank mounted on the fuselage together with a pump.

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