JP2006291989A - Actuator control device and working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator control device easily enlarging the range of a fine operation region regardless of the state of an actuator. <P>SOLUTION: A pilot valve 48 is provided for pilot-operating a control valve 45 for controlling an operating fluid supplied to an actuator 26 from a main pump 42, with pilot pressure generated according to a manual operation quantity. Proportioning pressure reducing valves 51, 52 for reducing output secondary pressure Pco on the control valve 45 side to a predetermined ratio to input secondary pressure Pc on the pilot valve 48 side are provided in pilot passages 46a, 46b and 47a, 47b between the pilot valve 48 and the control valve 45. Solenoid selector valves 53, 54 are provided for switching the proportioning pressure reducing valves 51, 52 into a pressure-reducing operating state and a non-operating state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an actuator control device that controls an actuator by a control valve that is pilot-operated by a pilot pressure generated from a pilot valve, and a work machine equipped with the actuator control device.

  Conventionally, a circuit shown in FIG. 7 is generally used to switch operability between a normal work such as excavation work and a crane work that requires fine operation in a hydraulic excavator.

  In FIG. 7, reference numeral 1 denotes an engine, and a discharge port of a hydraulic pump 2 driven by the engine 1 communicates with a supply port of a control valve 3 that controls the direction and flow rate of hydraulic oil discharged from the hydraulic pump 2. The output port of the control valve 3 is connected to an actuator 4 such as a hydraulic cylinder. The control valve 3 is pilot-operated by a pilot pressure supplied through a pilot passage from a pilot valve (remote control valve) 5 operated by an operator.

  In the pilot passage between the control valve 3 and the pilot valve 5, electromagnetic proportional pressure reducing valves 6 and 7 are interposed, and these electromagnetic proportional pressure reducing valves 6 and 7 are controllers for controlling these electromagnetic proportional pressure reducing valves 6 and 7. 8 is connected to the output section of the controller 8, and to the input section of the controller 8 is connected a mode switching operation unit 9 for switching the work mode. A pilot hydraulic pressure source 10 for supplying a pilot primary pressure is connected to the pilot pressure supply port of the pilot valve 5, and a tank 11 is connected to the pilot oil return port.

  FIG. 8 shows the relationship between the lever operation amount of the conventional pilot valve 5 and the pilot secondary pressure output from the pilot valve 5. In the conventional circuit of FIG. , 7 are fully excited, and the pilot secondary pressure output from the pilot valve 5 is directly supplied to the control valve 3 as indicated by broken lines in FIG. On the other hand, in a crane operation requiring fine operation, the pilot secondary pressure output from the pilot valve 5 is limited to a predetermined pressure by the electromagnetic proportional pressure reducing valves 6 and 7, as shown by a solid line in FIG. Has been depressurized.

When the piston displacement of the hydraulic cylinder detected by the displacement detector is close to the stroke end, the control unit restricts the piston displacement amount and pilot pressure of the hydraulic cylinder read from the built-in ROM. Based on the data in the correspondence table that correlates the values, the limit value corresponding to the piston displacement detected by the displacement detector is calculated, the drive signal corresponding to the limit value is output to the pressure reducing valve, and the manually operated valve is By restricting the pilot pressure supplied via the piston, the piston of the hydraulic cylinder approaches the stroke end, and without detecting the moving direction, while reliably mitigating the impact caused by the collision between the piston and the cover wall surface, Do not impair the operability when the piston is separated from the stroke end or when fine operation is performed with the piston located near the stroke end. There hydraulic working machine of the buffer controller that (for example, see Patent Document 1).
JP-A-8-200304 (first page, FIG. 1)

  In the prior art shown in FIG. 7, the pilot secondary pressure is reduced by the electromagnetic proportional pressure reducing valves 6 and 7 to limit the pilot maximum pressure in a crane operation or the like that requires fine operation. Since the increase gradient of the pilot secondary pressure with respect to the amount of operation lever is the same, there is a problem that the range of the fine operation area is narrow and it is difficult to operate.

  Further, in the prior art described in Patent Document 1, the improvement in operability when performing fine manipulation work is limited to when the piston of the hydraulic cylinder is separated from the stroke end or in a state where the piston is located near the stroke end. There is a problem, and it is trying to improve the fine operability by electrically controlling the output current to the pressure reducing valve by the control unit. However, a sensor for detecting cylinder displacement in hardware is required and the control unit There is a problem that the configuration becomes complicated, and further, complicated software for control is required.

  The present invention has been made in view of these points, and an object of the present invention is to provide an actuator control device that can easily expand the range of the fine operation range regardless of the state of the actuator, and a work machine equipped with the actuator control device. It is what.

  According to the first aspect of the present invention, there is provided a control valve for controlling a working fluid supplied from a pump to an actuator, a pilot valve for piloting the control valve with a pilot pressure generated according to a manual operation amount, and a pilot valve and a control valve. The constant ratio pressure reducing valve that is provided in the pilot passage between the pilot valve and reduces the pressure on the outlet side on the control valve side to a predetermined ratio with respect to the inlet side pressure on the pilot valve side, and the constant ratio pressure reducing valve is in the reduced pressure operation state and inactive And a switching means for switching to a state, and when the pilot valve is finely operated, the constant ratio pressure reducing valve is switched to the pressure reducing operation state by the switching means, and the final operation amount for the pilot valve is determined. By reducing the pilot pressure gradient, the same operating amount of the pilot valve On the other hand, the pilot pressure finally output from the pilot valve is reduced, the valve displacement of the control valve is reduced, and the operating speed of the actuator is reduced. It is possible to expand to.

  According to a second aspect of the present invention, the switching means in the actuator control apparatus according to the first aspect includes an electromagnetic switching valve that outputs a switching pressure for switching the constant ratio pressure reducing valve, and is output from the electromagnetic switching valve. Since the constant ratio pressure reducing valve is switched depending on the presence or absence of the switching pressure, the constant ratio pressure reducing valve can be a simple pilot operated type having a structure not having an electromagnetic operating portion.

  A third aspect of the invention is the actuator control device according to the first or second aspect, wherein the bypass passage is connected in parallel to the constant ratio pressure reducing valve, and the pilot passage on the control valve side is provided in the bypass passage. And a check valve for returning the pilot fluid to the neutral position pilot valve. When the pilot valve is returned to the neutral position, the pilot fluid in the pilot passage on the control valve side is in parallel with the constant pressure reducing valve. It quickly returns to the pilot valve in the neutral position via the check valve in the bypass passage connected to, and is discharged to the outside through the pilot valve in the neutral position, so control when the pilot valve is suddenly returned to the neutral position It becomes possible to quickly reduce the pilot pressure of the valve through the check valve. Actuator it is possible to quickly stop the.

  According to a fourth aspect of the present invention, there is provided an actuator according to any one of the first to third aspects, which controls an airframe, a work device that is mounted on the airframe and can be used for a plurality of operations, and an actuator that operates the airframe and the work device. A working machine equipped with a control device, and when performing normal work, the constant ratio pressure reducing valve is deactivated, and the operating speed of the actuator that operates the machine and the work device is controlled normally, while the machine When performing fine operation work that requires fine operability of the work equipment, the constant pressure reducing valve is switched to the pressure reducing operation state by the switching means to lower the final pilot pressure gradient with respect to the pilot valve operation amount. Therefore, the pilot pressure that is finally output from the pilot valve is reduced for the same operation amount of the pilot valve, and the valve displacement of the control valve Reduced, since lowering the operating speed of the actuator body and the working device, regardless of the state of the actuator can be easily extend the range of the fine operation range.

  According to a fifth aspect of the present invention, the machine body in the work machine according to the fourth aspect is provided with a boom that can be used for excavation work and crane work, wherein the upper turning body is turnable with respect to the lower traveling body. It is equipped with an arm and a bucket, and when excavating with the upper swing body, boom, arm and bucket, the constant pressure reducing valve is deactivated and the upper swing body, boom, arm and bucket are operated. The operating speed of the actuator to be controlled is controlled normally. On the other hand, when the crane is operated by the lower traveling body, the upper swing body, the boom, the arm and the bucket, the constant ratio pressure reducing valve is switched to the pressure reducing operation state by the switching means. By reducing the final pilot pressure gradient with respect to the valve operating amount, the pilot valve Luo finally reduces the pilot pressure output, reducing the valve displacement of the control valve, the lower traveling body, the upper rotating body, a boom, reducing an operating speed of the arm and the bucket actuator.

  According to the first aspect of the present invention, when the pilot valve is finely operated, the constant ratio pressure reducing valve is switched to the pressure reducing operation state by the switching means to lower the final pilot pressure gradient with respect to the pilot valve operation amount. Therefore, the pilot pressure that is finally output from the pilot valve is reduced for the same operation amount of the pilot valve, the valve displacement of the control valve is reduced, the operating speed of the actuator is reduced, and the state of the actuator is reduced. Regardless, since the range of the fine operation area can be easily expanded, the operability in the fine operation area can be significantly improved.

  According to the second aspect of the present invention, since the constant ratio pressure reducing valve is switched depending on the presence or absence of the switching pressure output from the electromagnetic switching valve, the constant ratio pressure reducing valve has a simple pilot operation type having a structure not having an electromagnetic operation portion. can do.

  According to the third aspect of the present invention, when the pilot valve is returned to the neutral position, the pilot fluid in the pilot passage on the control valve side passes through the check valve in the bypass passage connected in parallel with the constant ratio pressure reducing valve. Since the pilot valve returns to the neutral position quickly and is discharged to the outside through the neutral position pilot valve, the pilot pressure of the control valve is quickly reduced via the check valve when the pilot valve is suddenly returned to the neutral position. And the actuator can be quickly stopped.

  According to the fourth aspect of the present invention, when the normal operation is performed, the constant ratio pressure reducing valve is inactivated, and the operation speed of the actuator for operating the machine body and the work device is controlled normally, while the machine body and the work device are controlled. When performing fine operation work that requires a fine operability, the constant ratio pressure reducing valve is switched to the pressure reducing operation state by the switching means, and the final pilot pressure gradient with respect to the pilot valve operation amount is lowered to reduce the pilot pressure. Because the pilot pressure finally output from the pilot valve can be reduced for the same valve operation amount, the valve displacement of the control valve can be reduced, and the operating speed of the actuator of the machine and work equipment can be reduced. The range of the fine operation area can be easily expanded regardless of the state of the actuator.

  According to the fifth aspect of the present invention, when excavation work is performed with the upper swing body, boom, arm and bucket, the constant ratio pressure reducing valve is deactivated and the upper swing body, boom, arm and bucket are operated. On the other hand, when the crane is operated by the lower traveling body, the upper swing body, the boom, the arm and the bucket, the constant ratio pressure reducing valve is switched to the pressure reducing operation state by the switching means. By lowering the gradient of the final pilot pressure with respect to the operation amount, the pilot pressure finally output from the pilot valve is reduced for the same operation amount of the pilot valve, and the valve displacement amount of the control valve is reduced. It is possible to reduce the operating speed of the actuator of the lower traveling body, upper swing body, boom, arm and bucket. That.

  Hereinafter, the present invention will be described in detail with reference to one embodiment shown in FIG. 1 to FIG. 4 and another embodiment shown in FIG. 5 and FIG.

  First, an embodiment shown in FIGS. 1 to 4 will be described. FIG. 2 shows a hydraulic excavator 20 as a work machine, and this hydraulic excavator 20 is used for a machine body 21 for a plurality of operations. A possible working device 22 is mounted. The machine body 21 is provided such that an upper swing body 21b can turn relative to the lower travel body 21a, and the lower travel body 21a includes a crawler belt that is driven by a travel motor (not shown). A turning mechanism driven by a turning motor (not shown) is provided.

  The work device 22 includes a boom 23, an arm 24, and a bucket 25 that can be used for excavation work and crane work. The boom 23 is pivotally supported by the upper swing body 21b so as to be pivotable in the vertical direction, the arm 24 is pivotally pivoted at the tip of the boom 23, and the bucket 25 is pivotally pivoted at the tip of the arm 24. The boom 23 is rotated by a boom cylinder 26bm, the arm 24 is rotated by an arm cylinder 26am, and the bucket 25 is rotated by a bucket cylinder 26bk. A suspension 27 is pivotally coupled to the back surface of the bucket 25, and a suspended load 28 is suspended from a tip hook of the suspension 27.

  Actuators such as a traveling motor (not shown), a turning motor (not shown), a boom cylinder 26bm, an arm cylinder 26am, and a bucket cylinder 26bk are hydraulic motors or hydraulic cylinders, and the cab 31 mounted on the upper turning body 21b. A work operation lever 34a is installed in each of the console boxes 33 arranged on the left and right sides of the operator seat 32, and a traveling operation pedal and lever 34b are installed in front of the operator seat 32.

  In the following description, the travel motor (not shown), the swing motor (not shown), the boom cylinder 26bm, the arm cylinder 26am, and the bucket cylinder 26bk are collectively referred to as the actuator 26 that operates the machine body 21 and the work device 22, The work operation lever 34a and the travel operation pedal and lever 34b are collectively referred to as an operation lever 34.

  The hydraulic excavator 20 is provided with an actuator control device 40 for controlling the actuator 26 as shown in FIG.

  The actuator control device 40 includes a discharge passage from a main pump (variable displacement hydraulic pump) 42 as a pump driven by an engine 41 mounted on the upper swing body 21b, a main passage 43 connected to the actuator 26, 44 is provided with a control valve 45 for directional control and flow rate control of the working fluid supplied to the actuator 26, that is, hydraulic oil, to both ends of each spool which is a movable valve body corresponding to each actuator of the control valve 45. A pilot valve (remote control valve) 48 for supplying pilot pressure via the pilot passages 46a and 46b or the pilot passages 47a and 47b is provided.

  The pilot valve 48 pilot-operates the control valve 45 by a pilot fluid (oil) pressure generated according to a manual operation amount, that is, a pilot pressure, and a pilot passage 46a between the pilot valve 48 and the control valve 45, Constant ratio pressure reducing valves 51 and 52 are interposed in 46b and pilot passages 47a and 47b.

  These constant ratio pressure reducing valves 51 and 52 reduce the control valve 45 side, that is, the pilot passages 46b and 47b side outlet side pressure to a predetermined ratio with respect to the pilot valve 48 side, that is, the pilot passages 46a and 47a side inlet side pressure. These constant ratio pressure reducing valves 51 and 52 are provided with electromagnetic switching valves 53 and 54 as switching means for switching the constant ratio pressure reducing valves 51 and 52 to a pressure reducing operation state and a non-operation state, respectively. ing.

  Further, bypass passages 55 and 56 are respectively connected in parallel to the constant ratio pressure reducing valves 51 and 52, and the pilot fluid in the pilot passages 46b and 47b on the control valve 45 side is neutralized in the bypass passages 55 and 56, respectively. Check valves 57 and 58 for returning to the pilot valve 48 are provided.

  These check valves 57 and 58 are used for the pilot fluid pushed back from the control valve 45 to the pilot passage 46b or 47b when the control valve 45 returns to the neutral position, the pilot passage 46a or 47a, and the pilot valve 48 in the neutral position. After that, the tank 59 has a function of quickly discharging it.

  The control valve 45 includes a supply port 62 communicated with the variable capacity main pump 42 via a load hold check valve 61, a discharge port 64 communicated with a tank 59 mounted on the upper swing body 21b, and a main passage. 43 and 44, respectively, and a movable valve body or spool 68 having a center bypass passage 67 in a neutral position, and a balance between the pilot pressure acting on both ends of the spool 68 and the spring pressure. The displacement is controlled.

  In the pilot valve 48, a pair of pressure reducing valves 48a and 48b corresponds to one actuator 26, and receives a pilot original pressure, that is, a pilot primary pressure, from a pilot pressure source 71 such as a pilot pump through a pilot primary passage 72. The pilot pressure corresponding to the manual operation amount, that is, the pilot secondary pressure is output to one of the pilot passages 46a and 47a from one of the pressure reducing valves 48a and 48b located on the side where the operator manually operates the operation lever 34, and the pilot The pilot fluid returned from the other of the passages 46a and 47a is discharged from the other of the pressure reducing valves 48a and 48b to the tank 59.

  The constant ratio pressure reducing valves 51 and 52 are pilot secondary pressures of pilot passages 46b and 47b positioned on the output side of the pilot secondary pressure of the pilot passages 46a and 47a positioned on the input side, that is, the input secondary pressure Pc. The pressure, that is, the output secondary pressure Pco is reduced to a predetermined ratio.

  The electromagnetic switching valves 53 and 54 include a solenoid 73 that operates the movable valve body in one direction and a spring 74 that returns the movable valve body in the other direction, respectively, and pilot pressure action of the constant ratio pressure reducing valves 51 and 52. A switching pressure for switching these constant ratio pressure reducing valves 51 and 52 is output to the unit.

  Each solenoid 73 of these electromagnetic switching valves 53 and 54 is connected to an output unit of a controller 75 that controls the switching of these electromagnetic switching valves 53 and 54, and an operator of the hydraulic excavator 20 is connected to an input unit of this controller 75. Is connected to a mode switching operation unit 76 such as a changeover switch for switching the work mode. When a fine operation work mode such as a crane work mode is instructed by the mode switching operation device 76, a switching signal is energized to the solenoids 73 of the electromagnetic switching valves 53 and 54 from the controller 75, and the constant ratio pressure reducing valve 51 , 52 are switched to the decompression operation state, and when a normal operation mode such as excavation work is instructed from the mode switching operation unit 76, a spring is generated by turning off the energization of each solenoid 73 of the electromagnetic switching valves 53, 54 from the controller 75. By the returning action of 74, the constant ratio pressure reducing valves 51 and 52 are returned to the non-operating state.

  FIG. 3 shows details of the constant ratio pressure reducing valves 51 and 52. In these constant ratio pressure reducing valves 51 and 52, a spool 82 is fitted in a valve block 81 so as to be slidable in the axial direction. A small piston 83 is slidably fitted to the end face, and a coiled spring 84 is fitted to the small piston 83.

  The valve block 81 includes an inlet port 85 that communicates with the pilot passages 46a and 47a, a tank port 86 that communicates with the tank passage 60, an outlet port 87 that communicates with the pilot passages 46b and 47b, and the electromagnetic switching valves 53 and 54. A switching port 88 communicated with each other is provided.

  In the valve block 81, a pilot chamber 89 is formed on the lower side of the spool 82 in FIG. 3, and this pilot chamber 89 communicates with the outlet port 87 by an internal passage 90, and also serves as a spring chamber on the upper side of the spool 82 in FIG. A pilot chamber 91 is formed. The pilot chamber 91 is communicated with a switching port 88. A pilot chamber 93 is formed between the spool 82 and the small piston 83. The pilot chamber 93 is formed by a passage 94 in the spool. The inlet port 85 is communicated.

  A circumferential groove 95 is formed on the outer peripheral surface of the spool 82, and an opening degree adjusting portion E is provided on one side of the circumferential groove 95 and an opening degree adjusting portion F is provided on the other side. When the spool 82 is displaced downward, the opening adjustment portion E opens, the inlet port 85 and the outlet port 87 communicate with each other through the circumferential groove 95, and when the spool 82 is displaced upward, the opening adjustment portion F opens, The outlet port 87 and the tank port 86 communicate with each other through the circumferential groove 95.

  The operation principle of the constant ratio pressure reducing valves 51 and 52 will be described with reference to FIGS.

(A) When the electromagnetic switching valves 53 and 54 are de-energized If the pilot valve 48 is operated with the solenoid switching valves 53 and 54 not excited, the switching port 88 changes to the pilot chamber 91 and the inlet port The input secondary pressure Pc output from the pilot valve 48 is guided from 85 to the pilot chamber 93 at the tip of the small piston 83. On the other hand, the output secondary pressure Pco of the outlet port 87 is guided to the pilot chamber 89.

Considering the balance of the forces acting on the spool 82 of the constant ratio pressure reducing valves 51 and 52 at this time, the force Fa acting on the spool 82 is the outer diameter D of the spool 82 facing the pilot chamber 89 on the outlet side. And the output secondary pressure Pco of the outlet port 87 decompressed by the constant ratio pressure reducing valves 51 and 52,
Fa = A1 ・ Pco ……… (1)
It becomes.

On the other hand, the force Fb acting on the spool 82 in the downward direction is an annular pressure receiving area A2 due to the difference between the outer diameter D of the spool 82 facing the pilot chamber 91 and the outer diameter d of the small piston 83, and Due to the pressure receiving area A3 by the outer diameter d, the pilot secondary pressure of the pilot passages 46a and 47a, that is, the input secondary pressure Pc, and the acting force W of the spring 84,
Fb = A2 / Pc + A3 / Pc + W (2)
It becomes.

Here, if the forces in both directions acting on the spool 82 are balanced, the equations (1) and (2) are equal,
Fa = Fb
That is,
A1 / Pco = A2 / Pc + A3 / Pc + W (3)
It becomes.

Here, substituting and organizing the relationship of A1 = A2 + A3,
Pco = Pc + W / A1 (4)
However, even if the output secondary pressure Pco becomes equal to the input secondary pressure Pc on the supply side, the equation (4) does not hold, and the spool 82 is moved downward by the amount of the acting force W of the spring 84. As a result, the acting force increases, and as a result, the spool 82 is displaced by the maximum stroke in the downward direction, and the opening degree adjusting unit E shown in FIG. 3 is fully opened and the opening degree adjusting unit F is fully closed. Therefore, the inlet port 85 of the input secondary pressure Pc and the outlet port 87 of the output secondary pressure Pco communicate with each other through the circumferential groove 95 at the maximum opening degree.
Pco = Pc (5)
Thus, the pilot secondary pressure output from the pilot valve 48 to one of the pilot passages 46a and 47a is output as it is to one of the pilot passages 46b and 47b without being reduced by the constant ratio pressure reducing valves 51 and 52.

  That is, the constant ratio pressure reducing valves 51 and 52 are in a non-operating state, which corresponds to the normal work mode indicated by the dotted line in FIG. 4, and can perform normal work such as excavation work and dismantling work efficiently. .

(B) When the electromagnetic switching valves 53 and 54 are excited When the pilot valve 48 is operated while the electromagnetic switching valves 53 and 54 are excited, the output secondary pressure Pco is output from the outlet port 87 to the pilot chamber 89. , And the input secondary pressure Pc is led to the pilot chamber 93 from the inlet port 85, but the pilot chamber 91 is opened to the tank 59, so there is almost no pressure.

Accordingly, the force Fa acting on the spool 82 in the upward direction is the same as that in the expression (1), but the force Fc acting on the spool 82 in the downward direction is applied to the tank passage 60 by the pilot chamber 91 by the electromagnetic switching valves 53 and 54. Because it communicates
Fc = A3 ・ Pc + W (6)
It becomes. Here, from equation (1) = (6), that is, Fa = Fc,
Pco = (A3 ・ Pc + W) / A1 (7)
Get. Therefore, the output secondary pressure Pco is determined by the input secondary pressure Pc, the pressure receiving area A1 due to the outer diameter D of the spool 82, the pressure receiving area A3 due to the outer diameter d of the small piston 83, and the acting force W of the spring 84. Depressurized to value.

  Thus, when the constant ratio pressure reducing valves 51 and 52 are in the pressure reducing operation state, the above equation (7) is actually established by the metering of the opening degree adjusting unit E and the opening degree adjusting unit F of the spool 82. The output secondary pressure Pco is adjusted.

  As a result, the input secondary pressure Pc output from the pilot valve 48 to one of the pilot passages 46a and 47a is reduced by a constant ratio (A3 / A1) by one of the constant ratio pressure reducing valves 51 and 52, and FIG. As indicated by a solid line having a lower gradient than the dotted line, the output secondary pressure Pco is output to one of the pilot passages 46b and 47b, which is suitable for fine operation work such as crane work.

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

  When the pilot valve 48 is finely operated, the constant ratio pressure reducing valves 51 and 52 are switched to the pressure reducing operation state by the electromagnetic switching valves 53 and 54, and the operation amount of the pilot valve 48 is changed as indicated by the solid line from the dotted line in FIG. By lowering the gradient of the final pilot pressure (output secondary pressure Pco), the pilot pressure (output secondary pressure Pco) that is finally output from the pilot valve 48 for the same operation amount of the pilot valve 48 is reduced. Since the operating speed of the actuator 26 can be reduced by reducing the valve displacement amount of the control valve 45, the range of the fine operation range can be easily expanded regardless of the state of the actuator 26 such as the cylinder expansion / contraction stroke. The operability in the fine operation area can be greatly improved.

  For example, in FIG. 4, when the fine operation is performed within the limited pilot pressure (output secondary pressure Pco) Pa, the lever operation amount is limited to L1 in the normal operation mode. In the fine operation work mode in which the constant ratio pressure reducing valves 51 and 52 are switched to the pressure reducing operation state, the lever operation amount can be increased to L2, so that the operability can be improved.

  Further, in the prior art, fine operability can be obtained only when the piston displacement of the hydraulic cylinder is close to the stroke end. However, according to the present embodiment, fine operation is performed in the full stroke of the actuator 26. The area can be secured and the operability can be greatly improved.

  Further, since the constant ratio pressure reducing valves 51 and 52 are switched depending on the presence or absence of the switching pressure (that is, the input secondary pressure Pc) output from the electromagnetic switching valves 53 and 54, the constant ratio pressure reducing valves 51 and 52 have an electromagnetic operation section. It can be a simple pilot operation type with no structure. In other words, it is possible to expand the fine operation range by electrically controlling the output current to the pressure reducing valve by the control unit as in the conventional case, but the cylinder displacement detection sensor is necessary in terms of hardware and control. The configuration in the unit becomes complicated, and there is a problem that complicated software for control is required. On the other hand, the constant ratio pressure reducing valves 51 and 52 are used. Since only the electromagnetic switching valves 53 and 54 to be controlled are applicable, the configuration can be simplified.

  When the pilot valve 48 is returned to the neutral position, the pilot fluid in the pilot passages 46b and 47b on the control valve 45 side is checked in the bypass passages 55 and 56 connected in parallel with the constant ratio pressure reducing valves 51 and 52. Since the valve 57, 58 is quickly returned to the pilot valve 48 in the neutral position and is discharged to the tank 59 through the pilot valve 48 in the neutral position, when the pilot valve 48 is suddenly returned to the neutral position, the control valve 45 The pilot pressure acting on the valve can be quickly reduced via the check valves 57 and 58, and the actuator 26 can be stopped quickly.

  When performing normal work such as excavation work, the constant ratio pressure reducing valves 51 and 52 are deactivated, and the operating speed of the actuator 26 that operates the airframe 21 and the work device 22 is normally controlled. When performing fine operation work that requires fine operability of the work device 22, the constant ratio pressure reducing valves 51, 52 are switched to the pressure reducing operation state by the electromagnetic switching valves 53, 54, and the final operation amount of the pilot valve 48 is controlled. The pilot pressure (output secondary pressure Pco) that is finally output from the pilot valve 48 is reduced with respect to the same operation amount of the pilot valve 48 by lowering the gradient of the effective pilot pressure (output secondary pressure Pco) Therefore, the amount of displacement of the control valve 45 can be reduced, and the operating speed of the actuator 26 of the airframe 21 and the work device 22 can be reduced. Not easily allowed to extend the range of the fine operation range, it is possible to improve the operability.

  Specifically, when excavation work is performed by operating the upper swing body 21b, the boom 23, the arm 24 and the bucket 25, the upper swing body 21b, The operating speed of each actuator 26 of the boom 23, the arm 24 and the bucket 25 is normally controlled, while the suspended load 28 is transferred by the lower traveling body 21a, the upper turning body 21b, the boom 23, the arm 24 and the bucket 25 and lifted and lowered. When carrying out crane work, the constant ratio pressure reducing valves 51 and 52 are switched to the pressure reducing operation state by the electromagnetic switching valves 53 and 54, and the gradient of the final pilot pressure (output secondary pressure Pco) with respect to the operation amount of the pilot valve 48 , The pilot pressure (output secondary pressure Pco) finally output from the pilot valve 48 is reduced with respect to the same operation amount of the pilot valve 48, and the valve displacement amount of the control valve 45 is reduced. Lower travel The operating speed of the travel motor of the body 21a, the swing motor of the upper swing body 21b, the boom cylinder 26bm, the arm cylinder 26am, and the bucket cylinder 26bk can be reduced.

  Next, another embodiment shown in FIGS. 5 and 6 will be described. Parts similar to those in the embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.

  The embodiment shown in FIGS. 1 to 4 is an example in which the electromagnetic switching valves 53 and 54 are provided for the pilot chamber 91 on the spring 84 side of the constant ratio pressure reducing valves 51 and 52. 5 and another embodiment shown in FIG. 6 is an example in which the electromagnetic switching valves 53, 54 are provided for the pilot chamber 89 on the opposite side of the constant ratio pressure reducing valves 51, 52 from the spring 84 side. The electromagnetic switching valves 53 and 54 are provided between the pilot passages 46 b and 47 b communicating with the output port 87 and the port 96 of the pilot chamber 89. Further, the pilot chamber 91 that also serves as a spring chamber communicates with the tank port 86 through an internal passage 97.

  When the electromagnetic switching valves 53 and 54 are de-excited, the pilot chamber 89 is guided to the tank 59 through the port 96, and there is almost no pressure in the pilot chamber 89. The spool 82 is pushed downward by the input secondary pressure Pc from the pilot valve 48 thus guided, and the inlet port 85 and the outlet port 87 communicate with each other through the circumferential groove 95 of the spool 82. As a result, the output secondary pressure Pco from the constant ratio pressure reducing valves 51 and 52 is output without being reduced as the input secondary pressure Pc.

  On the other hand, when the electromagnetic switching valves 53 and 54 are excited, the output secondary pressure Pco of the outlet port 87 is guided to the pilot chamber 89. Therefore, the force Fa acting on the spool 82 in the upward direction is A1 · Pco. Yes, the expression (1) is established, and the input secondary pressure Pc is guided to the pilot chamber 93, and the pilot chamber 91 is opened to the tank 59 so that there is almost no pressure, so that the force Fc acting on the spool 82 downward is provided. Is A3 · Pc + W, and equation (6) is established, so that the input secondary pressure Pc is reduced at a constant ratio by the same action as in the previous embodiment, and similarly switching from normal work to fine operation work. It can correspond to.

  As described above, the present invention can solve the problem that the fine operation area of the prior art is narrow without using a complicated control system, can secure a wide fine operation area, and can greatly improve the operability.

  The present invention is not limited to only mode switching between excavation work and crane work, but can also be applied to other work that requires fine operability.

It is a circuit diagram showing one embodiment of an actuator control device concerning the present invention. It is a side view at the time of using the working machine carrying an actuator control apparatus same as the above for crane work. It is model sectional drawing which shows the constant ratio pressure reducing valve of an actuator control apparatus same as the above. It is a characteristic figure of the lever operation amount and pilot pressure of the actuator control device same as the above. It is a circuit diagram which shows other embodiment of the actuator control apparatus which concerns on this invention. It is a model sectional view showing a constant ratio pressure reducing valve in another embodiment. It is a circuit diagram which shows the conventional actuator control apparatus. It is the characteristic figure of the conventional lever operation amount and pilot pressure.

Explanation of symbols

21 Aircraft
21a Undercarriage
21b Upper swing body
22 Work equipment
23 Boom
24 arms
25 buckets
26 Actuator
40 Actuator controller
42 Main pump as a pump
45 Control valve
46a, 46b, 47a, 47b Pilot passage
48 Pilot valve
51, 52 Constant pressure reducing valve
53, 54 Switching means (electromagnetic switching valve)
55, 56 Bypass passage
57, 58 Check valve

Claims (5)

A control valve for controlling the working fluid supplied from the pump to the actuator;
A pilot valve that pilot-operates with a pilot pressure generated according to the amount of manual operation of the control valve;
A constant ratio pressure reducing valve provided in a pilot passage between the pilot valve and the control valve for reducing the pressure on the outlet side on the control valve side to a predetermined ratio with respect to the pressure on the pilot valve side;
An actuator control device comprising switching means for switching the constant ratio pressure reducing valve between a pressure reducing operation state and a non-operation state. The actuator control device according to claim 1, wherein the switching means includes an electromagnetic switching valve that outputs a switching pressure for switching the constant ratio pressure reducing valve. A bypass passage connected in parallel to the constant ratio pressure reducing valve;
The actuator control device according to claim 1 or 2, further comprising: a check valve provided in the bypass passage and returning the pilot fluid in the pilot passage on the control valve side to the pilot valve in the neutral position. The aircraft,
A working device that is mounted on the fuselage and can be used for multiple tasks;
An actuator control device according to any one of claims 1 to 3, which controls an actuator that operates the machine body and the work device. The aircraft is provided so that the upper swinging body can turn relative to the lower traveling body,
The work machine includes a boom, an arm, and a bucket that can be used for excavation work and crane work.

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