JP4460354B2 - Control device for fluid pressure circuit - Google Patents

Description

  The present invention relates to a control device for a fluid pressure circuit that supplies a working fluid from a plurality of fluid pressure sources to an actuator via a plurality of control valves.

  FIG. 5 shows a hydraulic excavator as a construction machine or a working machine, and an upper swing body 33 is swingably provided on a lower traveling body 31 via a swing bearing portion 32, and a power section 34 is provided on the upper swing body 33. The cab 35 and the work device 36 are mounted. In the working device 36, the base end of the boom 37 is pivotally supported on the upper swing body 33, an arm 38 is pivotally supported on the distal end of the boom 37, and an attachment 39 is attached to the distal end of the arm 38. The boom 37 is rotated by the boom cylinder 26, the arm 38 is rotated by the arm cylinder 21, the attachment 39 is rotated by the bucket cylinder 28, and the attachment is an attachment actuator. Actuated by cylinder 15.

  As a hydraulic circuit applied to a hydraulic excavator having such an attachment 39, when an excessive circuit pressure is not generated in the independent attachment circuit, the controller outputs an electric signal proportional to the operation signal for attachment to the electromagnetic proportional pressure. A controller that outputs to the control valve and can control the stroke of the shunt control valve via this electromagnetic proportional pressure control valve. On the other hand, if an excessive circuit pressure is generated in the independent attachment circuit, the controller detects the state via the pressure sensor. However, it can be controlled to reduce the amount of oil supplied to the independent attachment circuit by controlling the electromagnetic proportional pressure control valve regardless of the operation signal for attachment and reducing the opening area of the variable restrictor of the shunt control valve to a small value. As a result, the amount of oil supplied to the independent attachment circuit is reduced and supplied to the permanent actuator circuit. Aggressive media volume can recover, the attachment between the permanent actuator can smoothly synchronous operation, there is that to be able to improve the workability of the hydraulic excavator (e.g., see Patent Document 1).

  In addition, when the attachment circuit pressure becomes close to the relief pressure in the interlocking operation between the attachment and the actuator on the main body side, the preferential flow branched from the pressure-compensating shunt valve to the external passage flows to the tank via the switching valve, so that the pump Since the discharge flow rate increases and a large amount of flow is supplied to the actuator on the main unit side, when the attachment circuit pressure becomes close to the relief pressure in the interlocking operation of the attachment and main unit side actuator, the main unit side actuator There is one that can solve the problem of extremely slowing down the speed and improve workability (see, for example, Patent Document 2).

  The inventions described in these Patent Documents 1 and 2 are applied to a circuit having a shunt control valve, and cannot be applied to a circuit not having a shunt control valve.

  On the other hand, FIG. 6 shows a control device for a two-pump hydraulic circuit applied to a hydraulic excavator. The first control valve 2 and the arm second control valve 3 are attached to the line of the first hydraulic power source 1 such as a hydraulic main pump. However, the arm first control valve 5 and the attachment second control valve 6 are arranged in parallel on the line of the second hydraulic power source 4 such as a hydraulic main pump.

  In the hydraulic circuit shown in FIG. 6, when the electrical signal from the attachment extension electric remote control 7a is input to the controller 8, the attachment first control valve 2 is an electromagnetic proportional having the characteristics shown in FIG. Electrical signals are output to the pressure control valves 9a and 10a, and the pilot pressure supplied from the pilot hydraulic power source 11 such as a hydraulic pilot pump is further attached to the first pilot through the electromagnetic proportional pressure control valves 9a and 10a. Through the line 12a and the attachment extension second pilot line 13a, the pilot chamber 2a of the attachment first control valve 2 and the pilot chamber 6a of the attachment second control valve 6 are supplied to the attachment extension position, respectively.

  Thereby, the discharge pressure oil of the first hydraulic source 1 is supplied to the head chamber 15a of the attachment cylinder 15 via the attachment headline 14H, and the discharge pressure oil of the second hydraulic source 4 is supplied via the attachment headline 16H. It joins with the attachment head line 14H and is supplied to the head chamber 15a of the attachment cylinder 15, and the return oil from the attachment cylinder rod chamber 15b passes through the attachment rod line 14R via the attachment first control valve 2 and is also attached. By passing through the rod line 16R and flowing through the attachment second control valve 6 to the tank T, the attachment cylinder 15 moves in the extending direction.

  Next, when an electrical signal from the attachment contracted electric remote controller 7b is input to the controller 8, an electrical signal is output to the electromagnetic proportional pressure control valves 9b and 10b, and the pilot pressure supplied from the pilot hydraulic pressure source 11 is proportional to these electromagnetic proportional pressures. The attachment contraction first pilot line 12b and the attachment contraction second pilot line 13b are passed through the pressure control valves 9b and 10b, respectively, and the pilot chamber 2b of the attachment first control valve 2 and the pilot chamber of the attachment second control valve 6 respectively. By being supplied to 6b, it is switched to the attachment contraction position.

  Thereby, the discharge pressure oil of the first hydraulic source 1 is supplied to the rod chamber 15b of the attachment cylinder 15 via the attachment rod line 14R, and the discharge pressure oil of the second hydraulic source 4 is supplied via the attachment rod line 16R. It joins the attachment rod line 14R and is supplied to the rod chamber 15b of the attachment cylinder 15, and the return oil from the attachment cylinder head chamber 15a passes through the attachment head line 14H and is further attached via the attachment first control valve 2. By passing through the head line 16H and flowing through the attachment second control valve 6 to the tank T, the attachment cylinder 15 moves in the contracting direction.

  Next, the arm first control valve 5 receives the pilot pressure from the arm extension hydraulic remote control valve 19a to the arm extension pilot chamber 5a of the arm first control valve 5 via the arm extension first pilot line 18a. Switch to the extended position.

  As a result, the discharge pressure oil from the second hydraulic power source 4 is supplied to the arm head chamber 21a of the arm cylinder 21 through the arm head line 20H, and the arm extension second pilot line branched from the arm extension first pilot line 18a. The pilot pressure is supplied from the arm extension hydraulic remote control valve 19a to the arm extension pilot chamber 3a of the arm second control valve 3 through 22a, thereby switching to the arm extension position, and the discharge pressure oil of the first hydraulic source 1 is changed. The arm head line 23H passes through the arm head line 20H, and is supplied to the head chamber 21a of the arm cylinder 21, and the return oil in the cylinder rod chamber 21b passes through the arm rod line 20R to perform the arm first control. The arm cylinder 21 extends through the valve 5 and further through the arm rod line 23R and through the arm second control valve 3 to the tank T. Move in the direction, the arm 38 is lowered.

  Next, the arm first control valve 5 receives the pilot pressure from the arm contracting hydraulic remote control valve 19b to the arm contracting pilot chamber 5b of the arm first control valve 5 via the arm contracting first pilot line 18b. Switch to the contracted position.

  As a result, the discharge pressure oil from the second hydraulic power source 4 is supplied to the arm rod chamber 21b of the arm cylinder 21 through the arm rod line 20R, and the arm contraction second pilot line branched from the arm contraction first pilot line 18b. The pilot pressure is supplied from the arm contracting hydraulic remote control valve 19b to the arm contracting pilot chamber 3b of the arm second control valve 3 through 22b, thereby switching to the arm contracting position, and the discharge pressure oil of the first hydraulic source 1 is changed. The arm rod line 23R is joined to the arm rod line 20R and supplied to the rod chamber 21b of the arm cylinder 21, and the return oil in the cylinder head chamber 21a passes through the arm head line 20H, and the arm first control valve. 5 and further through the arm headline 23H and through the arm second control valve 3 to the tank T, the arm cylinder 21 is retracted. Movement, the arm 38 is raised.

  As for the boom raising, the boom cylinder 26 is operated by switching the boom first control valve 24 and the boom second control valve 25 to the boom raising position by the pilot pressure from the boom raising remote control valve (not shown). This is the same as the arm cylinder 21 and will not be described in detail.

  As for the bucket extension, the bucket cylinder 28 is extended by the bucket control valve 27 being switched to the bucket extension position by the pilot pressure from the bucket extension remote control valve (not shown), but the detailed explanation is omitted.

Each of the control valves 2, 3, 5, 6, 24, 25, 27 has a variable throttle function. From the electromagnetic proportional pressure control valves 9a, 10a, 9b, 10b or the hydraulic remote control valves 19a, 19b The speed of each actuator is controlled by shifting the spool by the supplied pilot pressure. FIG. 8 shows an opening characteristic taking the arm extension of the arm first control valve 5 as an example.
Japanese Patent No. 3511500 (page 3-6, FIG. 1) Japanese Patent No. 3511504 (page 3-5, FIG. 1)

  The conventional hydraulic circuit shown in FIG. 6 has the following problems.

(1) When the attachment contraction and arm extension are operated in the air, the load pressure of the head chamber 21a of the arm cylinder 21 that moves in the gravity direction due to its own weight in comparison with the rod chamber 15b of the attachment cylinder 15 where a heavy load is applied to the cylinder. Therefore, the supply oil from the first hydraulic power source 1 almost flows through the arm second control valve 3 into the head chamber 21a of the arm cylinder 21 having a low load pressure, and the supply oil from the second hydraulic power source 4 Flows through the arm first control valve 5 into the head chamber 21a of the arm cylinder 21 having a low load pressure, and therefore hardly flows into the rod chamber 15b of the attachment cylinder 15 and the attachment cylinder 15 hardly moves. There was a problem that the interlocking operability between the arm cylinder 21 and the attachment cylinder 15 was poor.

(2) Arm extension and attachment extension 2 When operating in a state where a sudden load is applied to the attachment cylinder 15 when interlocking operation is performed and the maximum cylinder thrust is required near the main relief pressure, Since the load pressure of the head chamber 21a of the arm cylinder 21 that moves by its own weight and falls slightly is lower, the supply oil from the first hydraulic source 1 passes through the arm second control valve 3 and the arm cylinder 21 having a low load pressure. Most of the oil flows into the head chamber 21a, and the oil supplied from the second hydraulic pressure source 4 flows through the arm first control valve 5 into the head chamber 21a of the arm cylinder 21 having a low load pressure. The head chamber 15a hardly flows and the pressure does not increase, so that there is a problem that the required thrust of the attachment cylinder 15 does not occur.

  Furthermore, when the maximum cylinder thrust near the main relief pressure is required in a work state where a sudden load is applied to the arm cylinder 21 by the same operation, the conventional technology uses the weight in the direction of gravity. Since the load pressure of the head chamber 15a of the attachment cylinder 15 moving in a falling manner is lower, the supply oil from the first hydraulic power source 1 passes through the attachment first control valve 2 and the head chamber of the attachment cylinder 15 having a low load pressure. The oil supplied from the second hydraulic power source 4 flows through the attachment second control valve 6 to the head chamber 15a of the attachment cylinder 15 having a low load pressure, so that the head chamber of the arm cylinder 21 There was a problem that the thrust of the required arm cylinder 21 was not generated because the pressure hardly increased in 21a and the pressure did not increase.

(3) When the arm is retracted and the attachment is extended, the head chamber 15a of the attachment cylinder 15 moves in a gravity direction and falls in a gravity direction compared to the rod chamber 21b of the arm cylinder 21 where a heavy load is applied to the cylinder. Since the load pressure is lower, the supply oil from the first hydraulic pressure source 1 flows almost through the attachment first control valve 2 to the head chamber 15a of the attachment cylinder 15 with a lower load pressure, and from the second hydraulic pressure source 4. Oil flows through the attachment second control valve 6 into the head chamber 15a of the attachment cylinder 15 having a low load pressure, and therefore hardly flows into the rod chamber 21b of the arm cylinder 21, and the arm cylinder 21 is hardly There is a problem that the interlocking operability is poor because it does not shrink.

(4) Arm shrinkage and attachment shrinkage 2 When interlocking operation is performed, when the maximum cylinder thrust close to the main relief pressure is required in the working state in which a sudden load is applied to the attachment cylinder 15, Since the load pressure of the 21 rod chamber 21b is lower, the supply oil from the first hydraulic pressure source 1 flows almost through the arm second control valve 3 into the rod chamber 21b of the arm cylinder 21 having a low load pressure. The oil supplied from the second hydraulic power source 4 flows through the arm first control valve 5 into the rod chamber 21b of the arm cylinder 21 having a low load pressure, and therefore hardly flows into the rod chamber 15b of the attachment cylinder 15. Also, since the pressure does not increase, there is a problem that the required thrust of the attachment cylinder 15 does not come out.

  Furthermore, when the maximum cylinder thrust near the main relief pressure is required in a working state where a sudden load is applied to the arm cylinder 21 by the same operation, the rod of the attachment cylinder 15 is used in the prior art. Since the load pressure in the chamber 15b is lower, the supply oil from the first hydraulic pressure source 1 almost flows through the attachment first control valve 2 into the rod chamber 15b of the attachment cylinder 15 with a low load pressure, and the second The supply oil from the hydraulic source 4 flows through the attachment second control valve 6 to the rod chamber 15b of the attachment cylinder 15 having a low load pressure, and therefore hardly flows into the rod chamber 21b of the arm cylinder 21. Since the pressure does not increase, there is a problem that the required thrust of the arm cylinder 21 does not come out.

  The present invention has been made in view of the above points, and in a fluid pressure circuit provided with a plurality of sets of circuits for supplying a working fluid from a common fluid pressure source to a plurality of actuators via a plurality of control valves, An object of the present invention is to provide a control device for a fluid pressure circuit that improves the interlocking operability between actuators and that allows sufficient thrust to be obtained from an actuator that is subjected to a sudden load.

According to the first aspect of the present invention, the upper swing body is provided so as to be able to swing with respect to the lower traveling body, and a work device is mounted on the upper swing body, and the work device is rotated by the boom cylinder on the upper swing body. The base end of the boom is pivotally supported, and the arm that is rotated by the arm cylinder that extends and retracts to the tip of the boom is pivotally supported. The arm is pivoted by the bucket cylinder. In the work machine to which the attachment operated by the expansion and contraction attachment cylinder is attached, the operation device for the attachment and the extension command signal and the contraction command signal from the attachment operation device are processed and the electric signal is obtained. a controller for outputting, attachments elongation pilot pressure and attach in response to an electrical signal output from the controller An electromagnetic proportional pressure control valve for a plurality of attachments to be output by controlling the cement shrinkage pilot pressure, the is controlled in accordance with the attachment elongation pilot pressure and the attachment shrinkage pilot pressure output from the electromagnetic proportional pressure control valve for attachment Attachment first control valve and attachment second control valve for controlling hydraulic oil supplied from the first hydraulic source and the second hydraulic source to the attachment cylinder extending side and contracting side, respectively, and arm extension pilot pressure and arm corresponding to the operation amount a pilot valve for the arm for outputting the contraction pilot pressure, the arm cylinder extension side and the contraction of the first hydraulic pressure source and the second hydraulic pressure source is controlled in accordance with the arm extending pilot pressure and the arms contracted pilot pressure outputted from the pilot valve Hydraulic fluid supplied to the An arm first control valve and an arm second control valve to be controlled; a pressure sensor for detecting an arm extension pilot pressure and an arm contraction pilot pressure output from the pilot valve to the arm first control valve; A plurality of arm proportional pressure control valves for controlling the arm extension pilot pressure and the arm contraction pilot pressure output from the arm pilot valve to the arm second control valve in accordance with the electrical signal output from the arm; The controller, when performing a pilot operation of the attachment first control valve and the attachment second control valve to the contraction side via the electromagnetic proportional pressure control valve for attachment by the contraction command signal from the actuator for attachment, The arm expansion pressure of the arm 2nd control valve by the electromagnetic proportional pressure control valve By squeezing the lot pressure, the supply oil from the first hydraulic pressure source is controlled to flow relatively increased to the attachment cylinder side through the first control valve attachment for throttled by the arm second control valve When the arm first pilot valve and the arm second control valve are pilot-operated to the extension side by the arm extension pilot pressure from the arm pilot valve, the electromagnetic proportional pressure control for attachment is performed by the pressure signal from the pressure sensor. through the valve, by squeezing the attachment shrinkage pilot pressure attachment second control valve, arm cylinder side through the first control valve arm for supplying oil from the second hydraulic pressure source is focused by the attachment second control valve It is the control apparatus of the fluid pressure circuit which controls so that it may increase and flow relatively .

According to a second aspect of the present invention, an upper swing body is provided so as to be able to swing with respect to the lower traveling body, and a work device is mounted on the upper swing body, and the work device is rotated by a boom cylinder on the upper swing body. The base end of the boom is pivotally supported, and the arm that is rotated by the arm cylinder that extends and retracts to the tip of the boom is pivotally supported. The arm is pivoted by the bucket cylinder. In the work machine to which the attachment operated by the expansion and contraction attachment cylinder is attached, the operation device for the attachment and the extension command signal and the contraction command signal from the attachment operation device are processed and the electric signal is obtained. a controller for outputting, attachments elongation pilot pressure and attach in response to an electrical signal output from the controller An electromagnetic proportional pressure control valve for a plurality of attachments to be output by controlling the cement shrinkage pilot pressure, the is controlled in accordance with the attachment elongation pilot pressure and the attachment shrinkage pilot pressure output from the electromagnetic proportional pressure control valve for attachment Attachment first control valve and attachment second control valve for controlling hydraulic oil supplied from the first hydraulic source and the second hydraulic source to the attachment cylinder extending side and contracting side, respectively, and arm extension pilot pressure and arm corresponding to the operation amount a pilot valve for the arm for outputting the contraction pilot pressure, the arm cylinder extension side and the contraction of the first hydraulic pressure source and the second hydraulic pressure source is controlled in accordance with the arm extending pilot pressure and the arms contracted pilot pressure outputted from the pilot valve Hydraulic fluid supplied to the An arm first control valve and an arm second control valve to be controlled; a pressure sensor for detecting an arm extension pilot pressure and an arm contraction pilot pressure output from the pilot valve to the arm first control valve; A plurality of arm proportional pressure control valves for controlling the arm extension pilot pressure and the arm contraction pilot pressure output from the arm pilot valve to the arm second control valve in accordance with the electrical signal output from the arm; The controller uses the extension command signal from the attachment operation unit to perform the pilot operation of the attachment first control valve and the attachment second control valve to the extension side via the attachment electromagnetic proportional pressure control valve. Through the electromagnetic proportional pressure control valve, the arm extension of the arm second control valve By squeezing the pilots pressure, the supply oil from the first hydraulic pressure source is controlled to flow relatively increased to the attachment cylinder through the first control valve attachment for throttled by the arm second control valve, When the arm first pilot valve and the arm second control valve are pilot-operated to the extension side by the arm extension pilot pressure from the arm pilot valve, an electromagnetic proportional pressure control valve for attachment is provided by the pressure signal from the pressure sensor. through, by squeezing the attachment elongation pilot pressure attachment second control valve, the arm cylinder side through the first control valve arm for supplying oil from the second hydraulic pressure source is focused by the attachment second control valve It is a control device for a fluid pressure circuit that controls the flow so as to increase relatively .

According to a third aspect of the present invention, an upper swing body is provided so as to be rotatable relative to the lower traveling body, and a work device is mounted on the upper swing body, and the work device is rotated by a boom cylinder on the upper swing body. The base end of the boom is pivotally supported, and the arm that is rotated by the arm cylinder that extends and retracts to the tip of the boom is pivotally supported. The arm is pivoted by the bucket cylinder. In the work machine to which the attachment operated by the expansion and contraction attachment cylinder is attached, the operation device for the attachment and the extension command signal and the contraction command signal from the attachment operation device are processed and the electric signal is obtained. a controller for outputting, attachments elongation pilot pressure and attach in response to an electrical signal output from the controller An electromagnetic proportional pressure control valve for a plurality of attachments to be output by controlling the cement shrinkage pilot pressure, the is controlled in accordance with the attachment elongation pilot pressure and the attachment shrinkage pilot pressure output from the electromagnetic proportional pressure control valve for attachment Attachment first control valve and attachment second control valve for controlling hydraulic oil supplied from the first hydraulic source and the second hydraulic source to the attachment cylinder extending side and contracting side, respectively, and arm extension pilot pressure and arm corresponding to the operation amount a pilot valve for the arm for outputting the contraction pilot pressure, the arm cylinder extension side and the contraction of the first hydraulic pressure source and the second hydraulic pressure source is controlled in accordance with the arm extending pilot pressure and the arms contracted pilot pressure outputted from the pilot valve Hydraulic fluid supplied to the An arm first control valve and an arm second control valve to be controlled; a pressure sensor for detecting an arm extension pilot pressure and an arm contraction pilot pressure output from the pilot valve to the arm first control valve; A plurality of arm proportional pressure control valves for controlling the arm extension pilot pressure and the arm contraction pilot pressure output from the arm pilot valve to the arm second control valve in accordance with the electrical signal output from the arm; The controller uses the extension command signal from the attachment operation unit to perform the pilot operation of the attachment first control valve and the attachment second control valve to the extension side via the attachment electromagnetic proportional pressure control valve. The arm contraction power of the arm second control valve is passed through the electromagnetic proportional pressure control valve. By squeezing the pilots pressure, the supply oil from the first hydraulic pressure source is controlled to flow relatively increased to the attachment cylinder side through the first control valve attachment for throttled by the arm second control valve When the arm first control valve and the arm second control valve are pilot-operated to the contraction side by the arm contraction pilot pressure from the arm pilot valve, the electromagnetic proportional pressure control for attachment is performed by the pressure signal from the pressure sensor. through the valve, by squeezing the attachment elongation pilot pressure attachment second control valve, arm cylinder side through the first control valve arm for supplying oil from the second hydraulic pressure source is focused by the attachment second control valve It is the control apparatus of the fluid pressure circuit which controls so that it may increase and flow relatively .

According to a fourth aspect of the present invention, an upper swing body is provided so as to be able to swing with respect to the lower traveling body, and a work device is mounted on the upper swing body, and the work device is rotated on the upper swing body by a boom cylinder. The base end of the boom is pivotally supported, and the arm that is rotated by the arm cylinder that extends and retracts to the tip of the boom is pivotally supported. The arm is pivoted by the bucket cylinder. In the work machine to which the attachment operated by the expansion and contraction attachment cylinder is attached, the operation device for the attachment and the extension command signal and the contraction command signal from the attachment operation device are processed and the electric signal is obtained. a controller for outputting, attachments elongation pilot pressure and attach in response to an electrical signal output from the controller An electromagnetic proportional pressure control valve for a plurality of attachments to be output by controlling the cement shrinkage pilot pressure, the is controlled in accordance with the attachment extends pilot pressure and the attachment shrinkage pilot pressure output from the electromagnetic proportional pressure control valve for attachment Attachment first control valve and attachment second control valve for controlling hydraulic oil supplied from the first hydraulic source and the second hydraulic source to the attachment cylinder extending side and contracting side, respectively, and arm extension pilot pressure and arm corresponding to the operation amount a pilot valve for the arm for outputting the contraction pilot pressure, the arm cylinder extension side and the contraction of the first hydraulic pressure source and the second hydraulic pressure source is controlled in accordance with the arm extending pilot pressure and the arms contracted pilot pressure outputted from the pilot valve Hydraulic fluid supplied to the An arm first control valve and an arm second control valve to be controlled; a pressure sensor for detecting an arm extension pilot pressure and an arm contraction pilot pressure output from the pilot valve to the arm first control valve; A plurality of arm proportional pressure control valves for controlling the arm extension pilot pressure and the arm contraction pilot pressure output from the arm pilot valve to the arm second control valve in accordance with the electrical signal output from the arm; The controller, when performing a pilot operation of the attachment first control valve and the attachment second control valve to the contraction side via the electromagnetic proportional pressure control valve for attachment by the contraction command signal from the actuator for attachment, Arm contraction pie of arm 2nd control valve by electromagnetic proportional pressure control valve By squeezing the lot pressure, the supply oil from the first hydraulic pressure source is controlled to flow relatively increased to the attachment cylinder side through the first control valve attachment for throttled by the arm second control valve When the arm first control valve and the arm second control valve are pilot-operated to the contraction side by the arm contraction pilot pressure from the arm pilot valve, the electromagnetic proportional pressure control for attachment is performed by the pressure signal from the pressure sensor. through the valve, by squeezing the attachment shrinkage pilot pressure attachment second control valve, arm cylinder side through the first control valve arm for supplying oil from the second hydraulic pressure source is focused by the attachment second control valve It is the control apparatus of the fluid pressure circuit which controls so that it may increase and flow relatively .

According to the first aspect of the present invention, it is possible to prevent the supply oil from flowing to the arm cylinder side having a low load pressure and not flowing to the attachment cylinder side during the aerial interlocking operation of arm extension and attachment contraction. Can solve the problem that the operability of the interlocking becomes poor.

According to the second aspect of the present invention, when the maximum cylinder thrust near the main relief pressure is required in an operation state in which an abrupt load is applied to the attachment cylinder or the arm cylinder when the arm extension and the attachment extension 2 are interlocked. The problem that the supply oil flows to the cylinder side where the load pressure is low and the pressure does not increase can be solved, and sufficient cylinder thrust can be obtained.

According to the third aspect of the invention, it is possible to prevent the supply oil from flowing to the attachment cylinder side having a low load pressure and not flowing to the arm cylinder side during the aerial interlocking operation by the arm contraction and attachment extension 2 interlocking operation. This solves the problem that the arm cylinder does not move and the interlocking operability deteriorates.

According to the fourth aspect of the present invention, when the maximum cylinder thrust force close to the main relief pressure is required in a working state in which an abrupt load is applied to the attachment cylinder or the arm cylinder when the arm contraction and the attachment contraction 2 are interlocked. The problem that the supply oil flows to the cylinder side where the load pressure is low and the pressure does not increase can be solved, and sufficient cylinder thrust can be obtained.

  The present invention will be described below with reference to one embodiment shown in FIGS. In addition, the same code | symbol is attached | subjected to the part similar to FIG. 5 thru | or FIG. 8, and the description is abbreviate | omitted.

  FIG. 1 shows an embodiment of a control device for a hydraulic circuit as a fluid pressure circuit according to the present invention, and an attachment 39 is attached to a working device 36 in place of a bucket like the hydraulic excavator shown in FIG. In the same manner as the circuit shown in FIG. 6, the electric remote controllers 7a and 7b as the operating devices, the controller 8 for calculating the command signals from these electric remote controllers 7a and 7b, One electromagnetic proportional pressure control valve 9a, 9b, 10a, 10b that controls the pilot pressure in accordance with the electrical signal output from the controller 8, and these electromagnetic proportional pressure control valves 9a, 9b, 10a, 10b An actuator for attachment (hereinafter referred to as “attachment member”) as an actuator from the first hydraulic pressure source 1 as one fluid pressure source and the second hydraulic pressure source 4 as another fluid pressure source controlled by the pilot pressure. An attachment first control valve 2 as one first control valve and an attachment second control valve 6 as one second control valve for respectively controlling the hydraulic oil as the working fluid supplied to the cylinder 15); Hydraulic remote control valves 19a and 19b serving as pilot valves for outputting pilot pressure corresponding to the operation amount, and the first hydraulic pressure source 1 and the second hydraulic pressure source are controlled by the pilot pressures output from these hydraulic remote control valves 19a and 19b. 4 to other working actuators (hereinafter referred to as “arm cylinders”) 21 as other actuators, the arm first control valve 5 as the other first control valve for controlling the hydraulic fluid supplied to each other, and the other first actuators. The arm 2nd control valve 3 as 2 control valves is comprised.

  6 is different from the circuit shown in FIG. 6 in that the pressure sensors 41 and 42 for detecting the pilot pressure output from the hydraulic remote control valves 19a and 19b to the arm first control valve 5 and inputting the pilot pressure to the controller 8; 8 includes other electromagnetic proportional pressure control valves 43 and 44 for controlling the pilot pressure output from the hydraulic remote control valves 19a and 19b to the arm second control valve 3 in accordance with the electrical signal output from the controller 8. An attachment cylinder is applied to the electromagnetic proportional pressure control valves 9a, 9b, 10a, 10b and the electromagnetic proportional pressure control valves 43, 44 by calculating and processing electric signals input from the electric remote controls 7a, 7b and the pressure sensors 41, 42. This is the point of outputting an electric signal that improves the interlocking operability between the arm 15 and the arm cylinder 21.

  That is, the pressure sensor 41 is connected to the arm extension first pilot line 18a, the pressure sensor 42 is connected to the arm contraction first pilot line 18b, respectively, and the arm extension second pilot line 22a and the arm contraction second pilot line 22b are connected. Above, electromagnetic proportional pressure control valves 43 and 44 having characteristics as shown in FIG.

  As the electromagnetic proportional pressure control valves 9a, 9b, 10a, 10b and the electromagnetic proportional pressure control valves 43, 44, for example, an electromagnetic proportional pressure reducing valve or the like may be used.

  Here, taking the electromagnetic proportional pressure control valve 43 side as an example, the description of FIG. 2 will be made. Pp is the inlet side primary pressure, that is, the pilot pressure supplied from the arm extension hydraulic remote control valve 19a, and Px is the outlet side. The secondary pressure, that is, the pressure acting on the arm extension pilot chamber 3a of the arm second control valve 3, is zero when the current value is Im. Further, Pm is the maximum pressure that can be controlled when the current value is zero, and is assumed to be a value larger than the aforementioned Pp. Therefore, the secondary pressure is as shown by a solid line in the figure. .

(1) Consider the case where the arm extension and attachment contraction are performed in the air. When the attachment contraction operation is performed, an attachment lever signal is input from the attachment contraction electric remote controller 7b to the controller 8, and the electric signal is sent from the controller 8 to the electromagnetic proportional pressure in various patterns by devising the software according to the input value. Output to the control valve 43 is enabled.

  Here, when an electric signal is input to the electromagnetic proportional pressure control valve 43, the arm extension pilot pressure output to the arm extension pilot chamber 3a of the arm second control valve 3 according to the characteristics shown in FIG. It is controlled by.

  For example, as shown in FIG. 3, the arm extension pilot pressure can be controlled linearly with respect to the attachment lever signal (pattern 1), can also be controlled with a curve (pattern 2), or there is It is also possible to control so as not to be below a certain value (pattern 3).

  Further, when the arm is extended, an arm extension pilot pressure signal is input to the controller 8 from the pressure sensor 41. By devising the software according to the input value, the electrical signal is electromagnetically proportional from the controller 8 in various patterns. It is assumed that the pressure can be output to the pressure control valve 10b.

  When an electric signal is input to the electromagnetic proportional pressure control valve 10b, the attachment shrinkage of the attachment second control valve 6 to the pilot chamber 6b is controlled in various patterns according to the characteristics shown in FIG. For example, as shown in FIG. 4, the attachment contraction pilot pressure can be linearly controlled with respect to the arm extension pilot pressure (pattern 1 '), or can be controlled with a curve (pattern 2'). Alternatively, it can be controlled not to be below a certain value (pattern 3 ').

(2) At the time of arm extension and attachment extension 2 interlocking operation, as in (1), the attachment lever signal from the attachment extension electric remote control 7a and the arm extension pilot pressure signal from the arm extension hydraulic remote control valve 19a As shown in FIG. 3, the arm extension pilot pressure to the arm second control valve 3 is freely controlled by the electromagnetic proportional pressure control valve 43 in response to the attachment lever signal, and the arm extension pilot pressure detected by the pressure sensor 41 is controlled. The controller 8 receiving the signal controls the attachment extension pilot pressure in various patterns with respect to the arm extension pilot pressure as shown in FIG.

(3) At the time of aerial interlocking operation by arm contraction and attachment extension 2 interlocking operation, as in (1), the attachment lever signal from the attachment extension electric remote control 7a and the arm contraction pilot pressure from the arm contracting hydraulic remote control valve 19b 3, the arm contraction pilot pressure to the arm second control valve 3 is freely controlled by the electromagnetic proportional pressure control valve 44 and detected by the pressure sensor 42 with respect to the attachment lever signal as shown in FIG. 3. The controller 8 that has received the arm contraction pilot pressure signal controls the attachment extension pilot pressure in various patterns with respect to the arm contraction pilot pressure as shown in FIG. 4, for example.

(4) Even during arm shrinkage and attachment shrinkage 2 interlocking operation, as in (1), by the attachment lever signal from the attachment shrinkage electric remote control 7b and the arm shrinkage pilot pressure signal from the arm shrinkage hydraulic remote control valve 19b, As shown in FIG. 3, the arm contraction pilot pressure to the arm second control valve 3 is freely controlled by the electromagnetic proportional pressure control valve 44 in response to the attachment lever signal, and the arm contraction pilot pressure detected by the pressure sensor 42. The controller 8 that receives the signal controls the attachment contraction pilot pressure in various patterns with respect to the arm contraction pilot pressure as shown in FIG. 4, for example.

  Next, the function and effect of the above embodiment will be described.

(1) The head of the arm cylinder 21 connected to the arm 38 that moves by its own weight in the gravitational direction due to its own weight compared to the rod chamber 15b of the attachment cylinder 15 where a heavy load is applied to the cylinder during the air-linked operation of arm extension and attachment shrinkage In the hydraulic circuit shown in FIG. 1, the controller 8 causes the controller 8 to attach via the electromagnetic proportional pressure control valves 9b and 10b in response to the attachment lever signal from the attachment contraction electric remote control 7b. When piloting the first control valve 2 and the attachment second control valve 6 to the contraction side, the controller 8 controls the arm extension pilot pressure of the arm second control valve 3 by the electromagnetic proportional pressure control valve 43. , The oil supplied from the first hydraulic pressure source 1 passes through the attachment first control valve 2 and takes priority over the attachment cylinder 15 side. To flow in.

  Further, when the arm first control valve 5 and the arm second control valve 3 are pilot-operated to the extension side by the arm extension pilot pressure from the arm extension hydraulic remote control valve 19a, the controller 8 Controls the attachment contraction pilot pressure of the attachment second control valve 6 via the electromagnetic proportional pressure control valve 10b, so that the supply oil from the second hydraulic source 4 passes through the arm first control valve 5 and the arm cylinder. Give priority to the 21 side.

  Thus, as in the conventional hydraulic circuit shown in FIG. 6, most of the supplied oil flows to the arm cylinder 21 side where the load pressure is low and hardly flows to the attachment cylinder 15 side. There is no longer a problem that the operability of the interlocking will be poor due to little movement.

(2) At the time of arm extension and attachment extension 2 interlocking operation, as in (1), the controller 8 sends the attachment number via the electromagnetic proportional pressure control valves 9a and 10a according to the attachment lever signal from the attachment extension electric remote control 7a. 1 The control valve 2 and the attachment second control valve 6 are pilot-operated to the extension side. At that time, the controller 8 increases the arm extension pilot pressure of the arm second control valve 3 via the electromagnetic proportional pressure control valve 43. By controlling, the supply oil from the first hydraulic pressure source 1 flows preferentially to the attachment cylinder 15 through the attachment first control valve 2.

  Further, the arm first control valve 5 and the arm second control valve 3 are pilot-operated to the extension side by the arm extension pilot pressure from the arm extension hydraulic remote control valve 19a, and at that time, the pressure signal from the pressure sensor 41 is used. The controller 8 controls the attachment extension pilot pressure of the attachment second control valve 6 via the electromagnetic proportional pressure control valve 10a, so that the supply oil from the second hydraulic power source 4 causes the arm first control valve 5 to flow. Pass through the arm cylinder 21 side preferentially.

  In this way, when working with a sudden load on the attachment cylinder 15 or the arm cylinder 21, when the maximum cylinder thrust close to the main relief pressure is required, the supply oil flows to the cylinder with the lower load pressure. Sufficient cylinder thrust can be obtained without causing the pressure to increase.

(3) At the time of the aerial interlocking operation by the arm contraction and attachment extension 2 interlocking operation, the controller 8 controls the electromagnetic proportional pressure control valves 9a, 10a by the attachment lever signal from the attachment extension electric remote controller 7a as in (1). The attachment first control valve 2 and the attachment second control valve 6 are pilot-operated to the extension side through the controller 8. At this time, the controller 8 is connected to the arm of the arm second control valve 3 through the electromagnetic proportional pressure control valve 44. By controlling the contraction pilot pressure, the supply oil from the first hydraulic power source 1 flows preferentially to the attachment cylinder 15 side through the attachment first control valve 2.

  Further, the arm first control valve 5 and the arm second control valve 3 are pilot-operated to the contraction side by the arm contraction pilot pressure from the arm contraction hydraulic remote control valve 19b, and at that time, by the pressure signal from the pressure sensor 42 The controller 8 controls the attachment extension pilot pressure of the attachment second control valve 6 via the electromagnetic proportional pressure control valve 10a, so that the supply oil from the second hydraulic power source 4 causes the arm first control valve 5 to flow. Pass through the arm cylinder 21 side preferentially.

  Thus, as in the conventional hydraulic circuit shown in FIG. 6, most of the supplied oil flows to the attachment cylinder 15 side where the load pressure is low and hardly flows to the arm cylinder 21 side, so that the arm cylinder 21 is hardly There will be no loss of interlocking operability without moving.

(4) At the time of the arm contraction and attachment contraction 2 interlocking operation, as in (1), the controller 8 uses the attachment proportional signal from the attachment contraction electric remote control 7b to send the attachment first via the electromagnetic proportional pressure control valves 9b and 10b. 1 control valve 2 and attachment second control valve 6 are pilot-operated to the contraction side. At that time, controller 8 controls the arm contraction pilot pressure of arm second control valve 3 by electromagnetic proportional pressure control valve 44. As a result, the supply oil from the first hydraulic pressure source 1 passes through the attachment first control valve 2 preferentially to the attachment cylinder 15 side.

  Further, the arm first control valve 5 and the arm second control valve 3 are pilot-operated to the contraction side by the arm contraction pilot pressure from the arm contraction hydraulic remote control valve 19b, and at that time, by the pressure signal from the pressure sensor 42 The controller 8 controls the attachment contraction pilot pressure of the attachment second control valve 6 via the electromagnetic proportional pressure control valve 10b, so that the supply oil from the second hydraulic power source 4 causes the arm first control valve 5 to flow. Pass through the arm cylinder 21 side preferentially.

  In this way, when working with a sudden load on the attachment cylinder 15 or the arm cylinder 21, when the maximum cylinder thrust close to the main relief pressure is required, the supply oil flows to the cylinder with the lower load pressure. Sufficient cylinder thrust can be obtained without causing the pressure to increase.

(5) In the above description, the interlock operation between the arm 38 and the attachment 39 has been described as an example. However, the operation is controlled by the attachment 39 controlled by the electric remote controls 7a and 7b and a hydraulic remote control valve (not shown). In the interlocking operation with other work actuators, similarly, by incorporating the pressure sensors 41 and 42 and the electromagnetic proportional pressure control valves 43 and 44, it is possible to improve the interlocking operability and secure the actuator thrust. For example, the present invention may be applied with one actuator as the attachment cylinder 15 and the other actuator as the boom cylinder 26 or the like.

It is a circuit diagram showing one embodiment of a control device of a fluid pressure circuit concerning the present invention. It is a characteristic view of the electromagnetic proportional pressure control valves 43 and 44 in the control device same as above. It is a characteristic view which shows the arm expansion / contraction pilot pressure control pattern by the attachment lever signal in a control apparatus same as the above. It is a characteristic view which shows the attachment expansion / contraction pilot pressure control pattern by the arm expansion / contraction pilot pressure in a circuit same as the above. It is a side view of a hydraulic excavator. It is a circuit diagram which shows the control apparatus of the conventional hydraulic circuit. It is a characteristic view of the electromagnetic proportional pressure control valves 9a, 9b, 10a, 10b in the control device. It is a characteristic view which shows the arm expansion opening characteristic of the arm 1st control valve in a control apparatus same as the above.

Explanation of symbols

1 first hydraulic source 2 A Attachment first control valve 3 A over arm second control valve 4 second hydraulic pressure source 5 A over arm first control valve 6 A Attachment second control valve
Electric remote control as controller for 7a, 7b attachment 8 Controller
Solenoid proportional pressure control valve for 9a, 9b, 10a, 10b attachment
15 A Attachment Cylinders
Hydraulic remote control valve as pilot valve for 19a, 19b arm
21 A Mushirin da
26 boom cylinder
28 bucket cylinder
31 Lower body
33 Upper swing body
36 Work equipment
37 boom
38 arms
39 Attachment
41, 42 Pressure sensor
Electromagnetic proportional pressure control valve for 43 and 44 arms

Claims (4)

An upper swing body is provided so as to be able to swing with respect to the lower traveling body, and a work device is mounted on the upper swing body, and this work device has a base end of a boom rotated by a boom cylinder. An arm that is freely pivotally supported and is pivotally supported by the boom cylinder at the tip of the boom, and is pivotally supported at the tip of the arm. In work machines with attachments actuated by cylinders,
A controller for attachments;
A controller that calculates and outputs an extension command signal and a contraction command signal from an attachment operating device, and outputs an electrical signal ;
An electromagnetic proportional pressure control valve for a plurality of attachments that controls and outputs an attachment extension pilot pressure and an attachment contraction pilot pressure in accordance with an electrical signal output from the controller;
Electromagnetic proportional pressure control valve the hydraulic oil supplied from the first hydraulic pressure source and the second hydraulic pressure source to the attachment cylinder extending side and contracting side is controlled depending on the output attachment extending pilot pressure and the attachment shrinkage pilot pressure from the attachment An attachment first control valve and an attachment second control valve for respectively controlling
An arm pilot valve that outputs an arm extension pilot pressure and an arm contraction pilot pressure according to the operation amount; and
Arms that are controlled according to the arm extension pilot pressure and the arm contraction pilot pressure output from the pilot valve and control the hydraulic fluid supplied from the first hydraulic source and the second hydraulic source to the arm cylinder extension side and the contraction side, respectively. 1 control valve and arm second control valve;
A pressure sensor that detects an arm extension pilot pressure and an arm contraction pilot pressure output from the pilot valve to the arm first control valve, respectively, and inputs them to the controller;
A plurality of arm proportional pressure control valves for controlling the arm extension pilot pressure and the arm contraction pilot pressure output from the arm pilot valve to the arm second control valve in accordance with an electrical signal output from the controller; And
The controller
When the attachment first control valve and the attachment second control valve are pilot-operated to the contraction side via the attachment electromagnetic proportional pressure control valve by the shrinkage command signal from the attachment operation device, the electromagnetic proportional pressure control for the arm the valve arm by squeezing the arms extending pilot pressure of the second control valve, supplying oil from the first hydraulic pressure source relative to the attachment cylinder side through the first control valve attachment for throttled by the arm second control valve When the arm first pilot valve and the arm second control valve are pilot-operated to the extension side by the arm extension pilot pressure from the arm pilot valve, the pressure sensor outputs from the pressure sensor. By the pressure signal, the attachment second control is performed via the electromagnetic proportional pressure control valve for attachment. By squeezing the attachment shrinkage pilot pressure valve, supply oil from the second hydraulic source to flow relatively increased to the arm cylinder side through the first control valve arm for throttled by the attachment second control valve A control apparatus for a fluid pressure circuit. An upper swing body is provided so as to be able to swing with respect to the lower traveling body, and a work device is mounted on the upper swing body, and this work device has a base end of a boom rotated by a boom cylinder. An arm that is freely pivotally supported and is pivotally supported by the boom cylinder at the tip of the boom, and is pivotally supported at the tip of the arm. In work machines with attachments actuated by cylinders,
A controller for attachments;
A controller that calculates and outputs an extension command signal and a contraction command signal from an attachment operating device, and outputs an electrical signal ;
An electromagnetic proportional pressure control valve for a plurality of attachments that controls and outputs an attachment extension pilot pressure and an attachment contraction pilot pressure in accordance with an electrical signal output from the controller;
Electromagnetic proportional pressure control valve the hydraulic oil supplied from the first hydraulic pressure source and the second hydraulic pressure source to the attachment cylinder extending side and contracting side is controlled depending on the output attachment extending pilot pressure and the attachment shrinkage pilot pressure from the attachment An attachment first control valve and an attachment second control valve for respectively controlling
An arm pilot valve that outputs an arm extension pilot pressure and an arm contraction pilot pressure according to the operation amount; and
Arms that are controlled according to the arm extension pilot pressure and the arm contraction pilot pressure output from the pilot valve and control the hydraulic fluid supplied from the first hydraulic source and the second hydraulic source to the arm cylinder extension side and the contraction side, respectively. 1 control valve and arm second control valve;
A pressure sensor that detects an arm extension pilot pressure and an arm contraction pilot pressure output from the pilot valve to the arm first control valve, respectively, and inputs them to the controller;
A plurality of arm proportional pressure control valves for controlling the arm extension pilot pressure and the arm contraction pilot pressure output from the arm pilot valve to the arm second control valve in accordance with an electrical signal output from the controller; And
The controller
The electromagnetic proportional pressure control for the arm when the attachment first control valve and the attachment second control valve are pilot-operated to the expansion side via the electromagnetic proportional pressure control valve for attachment by the extension command signal from the actuator for attachment. By reducing the arm extension pilot pressure of the arm second control valve via the valve, the supply oil from the first hydraulic pressure source is throttled by this arm second control valve, so that the attachment cylinder passes through the attachment first control valve to the attachment cylinder. It controls to flow relatively increased, by an arm extending pilot pressure from the pilot valve for the arm, when the pilot operated side extending a first control valve and the arm second control valve arm, the pressure sensor The second pressure of the attachment is controlled by the pressure signal of the attachment via the electromagnetic proportional pressure control valve for attachment. By squeezing the attachment elongation pilot pressure valve, supply oil from the second hydraulic source to flow relatively increased to arm cylinder side through the first control valve arm for throttled by the attachment second control valve A control apparatus for a fluid pressure circuit. An upper swing body is provided so as to be able to swing with respect to the lower traveling body, and a work device is mounted on the upper swing body, and this work device has a base end of a boom rotated by a boom cylinder. An arm that is freely pivotally supported and is pivotally supported by the boom cylinder at the tip of the boom, and is pivotally supported at the tip of the arm. In work machines with attachments actuated by cylinders,
A controller for attachments;
A controller that calculates and outputs an extension command signal and a contraction command signal from an attachment operating device, and outputs an electrical signal ;
An electromagnetic proportional pressure control valve for a plurality of attachments that controls and outputs an attachment extension pilot pressure and an attachment contraction pilot pressure in accordance with an electrical signal output from the controller;
Electromagnetic proportional pressure control valve the hydraulic oil supplied from the first hydraulic pressure source and the second hydraulic pressure source to the attachment cylinder extending side and contracting side is controlled depending on the output attachment extending pilot pressure and the attachment shrinkage pilot pressure from the attachment An attachment first control valve and an attachment second control valve for respectively controlling
An arm pilot valve that outputs an arm extension pilot pressure and an arm contraction pilot pressure according to the operation amount; and
Arms that are controlled according to the arm extension pilot pressure and the arm contraction pilot pressure output from the pilot valve and control the hydraulic fluid supplied from the first hydraulic source and the second hydraulic source to the arm cylinder extension side and the contraction side, respectively. 1 control valve and arm second control valve;
A pressure sensor that detects an arm extension pilot pressure and an arm contraction pilot pressure output from the pilot valve to the arm first control valve, respectively, and inputs them to the controller;
A plurality of arm proportional pressure control valves for controlling the arm extension pilot pressure and the arm contraction pilot pressure output from the arm pilot valve to the arm second control valve in accordance with an electrical signal output from the controller; And
The controller
The electromagnetic proportional pressure control for the arm when the attachment first control valve and the attachment second control valve are pilot-operated to the expansion side via the electromagnetic proportional pressure control valve for attachment by the extension command signal from the actuator for attachment. through the valve, by squeezing the arm shrinkage pilot pressure of the arm second control valve, the attachment cylinder side through the first control valve attachment for supplying oil is throttled in the arm second control valve from the first hydraulic pressure source relatively increased amounts controls to flow, the arm shrinkage pilot pressure from the pilot valve for the arm, when the pilot operated side shrinkage of the first control valve and the arm second control valve arm, the pressure sensor The pressure signal from the attachment second via the electromagnetic proportional pressure control valve for attachment By squeezing the attachment elongation pilot pressure control valves, flow relatively increased to the arm cylinder side through the first control valve arm for supplying oil from the second hydraulic pressure source is focused by the attachment second control valve Control device for fluid pressure circuit, characterized in that An upper swing body is provided so as to be able to swing with respect to the lower traveling body, and a work device is mounted on the upper swing body, and this work device has a base end of a boom rotated by a boom cylinder. An arm that is freely pivotally supported and is pivotally supported by the boom cylinder at the tip of the boom, and is pivotally supported at the tip of the arm. In work machines with attachments actuated by cylinders,
A controller for attachments;
A controller that calculates and outputs an extension command signal and a contraction command signal from an attachment operating device, and outputs an electrical signal ;
An electromagnetic proportional pressure control valve for a plurality of attachments that controls and outputs an attachment extension pilot pressure and an attachment contraction pilot pressure in accordance with an electrical signal output from the controller;
Electromagnetic proportional pressure control valve the hydraulic oil supplied from the first hydraulic pressure source and the second hydraulic pressure source to the attachment cylinder extending side and contracting side is controlled depending on the output attachment extending pilot pressure and the attachment shrinkage pilot pressure from the attachment An attachment first control valve and an attachment second control valve for respectively controlling
An arm pilot valve that outputs an arm extension pilot pressure and an arm contraction pilot pressure according to the operation amount; and
Arms that are controlled according to the arm extension pilot pressure and the arm contraction pilot pressure output from the pilot valve and control the hydraulic fluid supplied from the first hydraulic source and the second hydraulic source to the arm cylinder extension side and the contraction side, respectively. 1 control valve and arm second control valve;
A pressure sensor that detects an arm extension pilot pressure and an arm contraction pilot pressure output from the pilot valve to the arm first control valve, respectively, and inputs them to the controller;
A plurality of arm proportional pressure control valves for controlling the arm extension pilot pressure and the arm contraction pilot pressure output from the arm pilot valve to the arm second control valve in accordance with an electrical signal output from the controller; And
The controller
When the attachment first control valve and the attachment second control valve are pilot-operated to the contraction side via the attachment electromagnetic proportional pressure control valve by the shrinkage command signal from the attachment operation device, the electromagnetic proportional pressure control for the arm the valve arm by squeezing the arm shrinkage pilot pressure of the second control valve, supplying oil from the first hydraulic pressure source relative to the attachment cylinder side through the first control valve attachment for throttled by the arm second control valve controls to flow increased to the manner, by the arm contraction pilot pressure from the pilot valve for the arm, when the pilot operating the first control valve and side contraction arm second control valve arm, from the pressure sensor By the pressure signal, the attachment second control is performed via the electromagnetic proportional pressure control valve for attachment. By squeezing the attachment shrinkage pilot pressure valve, supply oil from the second hydraulic source to flow relatively increased to the arm cylinder side through the first control valve arm for throttled by the attachment second control valve A control apparatus for a fluid pressure circuit.

Images