JP4890147B2 - Load holding device for hydraulic actuator circuit - Google Patents

Load holding device for hydraulic actuator circuit Download PDF

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Publication number
JP4890147B2
JP4890147B2 JP2006213526A JP2006213526A JP4890147B2 JP 4890147 B2 JP4890147 B2 JP 4890147B2 JP 2006213526 A JP2006213526 A JP 2006213526A JP 2006213526 A JP2006213526 A JP 2006213526A JP 4890147 B2 JP4890147 B2 JP 4890147B2
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pressure
pilot
load
valve
hydraulic
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JP2008039042A (en
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修栄 有賀
広二 石川
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日立建機株式会社
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  The present invention relates to a load holding device for a hydraulic actuator circuit, and in particular, in a hydraulic actuator circuit used in a work machine such as a hydraulic excavator or a demolition machine having a hydraulic excavator as a base, a deep hole excavator, etc. The present invention relates to a load holding device that prevents dropping of a load when a burst (breakage) or oil leakage occurs in a load side pipeline.

  For example, in the hydraulic actuator circuit of a boom of a hydraulic excavator, burst or oil leakage of a load side pipe connected to the load side of the actuator (the bottom side of the boom cylinder) in a situation where a load is applied to the hydraulic actuator (boom cylinder) There is provided a load holding device that prevents the work front (load) from dropping when a problem occurs. This load holding device has a configuration in which a holding valve is installed between the bottom side (load side) of the boom cylinder and the load side pipe, and this holding valve is opened and closed with an operating pilot pressure for raising the boom.

  In such a load holding device, Patent Document 1 discloses a holding valve control means for controlling the opening of the holding valve during the operation of the hydraulic actuator, and the holding valve opening during normal times when the pressure in the load side pipe line exceeds a certain value. Is set to a value sufficiently larger than the meter-out opening of the control valve at that time, and the holding valve opening is set in the event of an abnormal condition (when the load-side pipe bursts) when the pressure on the load-side pipe falls below a certain value. A configuration has been proposed in which the actuator speed is set to a value lower than that in the case where there is no holding valve. In addition, as a specific configuration, the pressure of the load side pipe is guided to the operation part of the holding valve, and the stroke characteristic with respect to the operation pilot pressure is shifted in the event of an abnormality (at the time of burst of the load side pipe), or the inclination is changed. By changing the configuration, the holding valve opening at a given lever operation amount is reduced, or the pressure on the load side pipe is led to the switching valve that adjusts the boom pilot operating pilot pressure. ) Shows a configuration in which the holding valve opening at a predetermined lever operation amount is reduced by reducing the increase rate of the operation pilot pressure with respect to the lever operation amount (decreasing the inclination).

JP 2004-60821 A

  In Europe, as a performance of load holding valve, when a holding valve is provided on the load side pipeline of the boom cylinder according to ISO8643, a test load that is 1/2 of the actual vehicle rated lifting capacity is applied, and the operating speed of the load is 200 mm. It is obliged that the cylinder speed (load dropping speed) when bursting the load side pipeline of the boom cylinder is less than twice its operating speed (400 mm / sec). Yes.

In the conventional general load holding valve, the combined opening of the meter-out opening and holding valve opening of the control valve satisfies the desired meter-out flow characteristics (operability), and the load at the time of bursting of the load side pipe line is reduced. It is necessary to set each opening area so that the falling speed satisfies the requirements of ISO8643. In this case, the hold valve opening setting must be adjusted to meet both the desired meter-out flow characteristics and the requirements of ISO8643. However, if the holding valve opening changes, the meter-out flow characteristic as a synthetic opening also changes. Therefore, when the holding valve opening is changed, the meter of the control valve is used to obtain the same meter-out flow characteristic as when the holding valve opening is not changed. It is necessary to correct the setting of the out opening. As a result, the meter-out opening and the holding valve opening of the control valve must be set by trial and error, and there is a problem that much labor is required for setting the meter-out opening and the holding valve opening of the control valve.

  In the load holding device described in Patent Document 1, the holding valve opening is set to a value sufficiently larger than the meter-out opening of the control valve during normal operation, and the holding valve opening at a predetermined lever operation amount is reduced during burst of the load side pipe line. Thus, by configuring the actuator speed to be lower than that without the holding valve, it is possible to easily set the holding valve opening while ensuring the meter-out flow rate characteristic at the normal time.

  However, the load holding device described in Patent Document 1 has the following problems.

  The load holding device described in Patent Document 1 utilizes the fact that the inside of the load side pipe becomes almost atmospheric pressure (lowers to a predetermined value or less) at the time of abnormality (during burst of the load side pipe), and the pressure change Thus, the holding valve opening at a predetermined lever operation amount is reduced by changing the operating characteristic of the holding valve (shifting or changing the inclination) or by adjusting the operating pilot pressure by throttling. The predetermined lever operation amount is a magnitude that sets the operating speed of the load at a normal time to 200 mm / sec. Therefore, when the load side pipeline bursts with the operating lever in the vicinity of the predetermined lever operating amount, the pilot pressure is appropriately reduced and the holding valve opening is controlled to the desired small opening, and the load The drop speed can be maintained at a desired value. However, if the operating lever is operated larger than the predetermined lever operating amount, for example, when the operating lever is operated to near full, the pilot at the load side pipeline burst The pressure does not drop to the desired value, so that the holding valve opening increases accordingly and there is a problem that the load drop rate increases.

  In addition, since it is essential to apply the high pressure of the load side pipe line to the operation side of the holding valve, the structure and strength of the operation side of the holding valve must be set to the high pressure specification, which leads to the manufacturing cost. There is also a problem that increases.

  Furthermore, expensive additional functions such as the addition of an oil passage in the holding valve and the addition of an assist cylinder are required, leading to an increase in manufacturing cost and the size of the holding valve, which increases the space occupied by the load holding device. .

  The first object of the present invention is to reliably reduce the opening area of the holding valve at the time of bursting of the load side pipe regardless of the operation amount of the operation lever, and to control the load dropping speed to a safe speed. It is to provide a load holding device for a hydraulic actuator circuit.

  The second object of the present invention is to provide an inexpensive and compact load holding device for a hydraulic actuator circuit in which the operation side configuration of the holding valve can be a low pressure specification and the configuration is relatively simple. is there.

(1) In order to achieve the above object, the present invention provides a hydraulic pump and a pilot pump, a hydraulic actuator driven by hydraulic pressure discharged from the hydraulic pump, and a pressure supplied from the hydraulic pump to the hydraulic actuator. Control valve for controlling oil and pressure oil discharged from the hydraulic actuator, pilot operating means for generating pilot pressure from the pressure oil discharged from the pilot pump and switching the control valve, the control valve and the control valve A hydraulic actuator circuit load holding device, wherein the hydraulic actuator circuit has a pair of hydraulic lines connected to the hydraulic actuator, and one of the pair of hydraulic lines is a load side line connected to a load side of the hydraulic actuator In between the load side of the hydraulic actuator and the load side pipeline A kicked retention valve has a pressure receiving portion a pilot pressure is guided from the hydraulic pilot operating section changes such that the opening area increases when the increased pilot pressure guided to the pressure receiving portion In addition, the pilot pressure is a predetermined first pilot pressure and the opening area is a first opening area smaller than the maximum opening area, and the opening area is the maximum when the pilot pressure is a second pilot pressure larger than the first pilot pressure. A holding valve that is set to be and a pressure receiving portion of the holding valve, and the hydraulic pilot operating means switches the control valve so as to discharge the hydraulic oil of the hydraulic actuator to the load side pipe line. a pilot line for guiding the pilot pressure to the pressure receiving portion at the time of, and the load-side pipe line to the pilot line Provided, it is assumed that the pressure of the load-side pipe is provided with a pressure control valve to control the pressure of the pilot conduit and equal to or less than a predetermined value does not become more than the first pilot pressure.

In this way, a pressure control valve that controls between the pilot line and the load side line so that the pressure in the pilot line does not become higher than the predetermined first pilot pressure when the pressure in the load side becomes lower than the predetermined value. In the present invention in which the pressure side control valve does not operate when the load side pipe is not bursting normally, the output pressure of the hydraulic pilot operating means is directly input to the control valve and the holding valve, and the hydraulic pilot operating means The speed of the hydraulic actuator can be controlled according to the operation.

On the other hand, when the load side pipeline bursts, the pressure in the load side pipeline drops to almost atmospheric pressure (below a predetermined value), so that the pressure control valve operates and the pressure in the pilot pipeline exceeds the predetermined first pilot pressure . It is controlled not to become. As a result, the opening area of the holding valve is limited to a small value corresponding to the set value, the opening area of the holding valve is surely reduced, and the load dropping speed is controlled to a safe speed to ensure work safety. be able to.

Further, the holding valve is set so that the opening area is maximized at a second pilot pressure that is greater than the first pilot pressure, so that when the pilot pressure reaches the second pilot pressure, The meter-out flow area of the control valve dominates the meter-out flow characteristics obtained by the holding valve, and the opening area of the holding valve has little effect, so that the desired meter-out flow characteristics (operability) are satisfied. In addition, it is possible to easily set and tune the opening area for controlling the load dropping speed at the burst time of the load side pipe line to a desired value.

(2) Further, in order to achieve the second object, the present invention is provided in the above (1) between the pressure control valve and the load side pipe, and A check valve for preventing the transmission of pressure to the control valve is further provided.

As a result, the high pressure of the load side pipeline does not act on the pressure control valve, so the configuration on the operation side of the holding valve including the pressure control valve can be an inexpensive low pressure specification, and the configuration is relatively simple and inexpensive. It can be set as a compact load holding device.

According to the first aspect of the present invention, regardless of the operation amount of the operation lever, the holding valve opening is surely made small when the load side pipe bursts, and the load dropping speed is limited to a safe speed. Safety can be ensured.
Furthermore, it is possible to easily set the opening area for satisfying a desired meter-out flow rate characteristic (operability) and controlling the load dropping speed at the time of burst of the load side pipe to a desired value.

According to the second aspect of the present invention, the configuration of the operation side of the holding valve can be a low pressure specification, the configuration is relatively simple, and the load holding device can be made inexpensive and compact.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a hydraulic circuit diagram showing only a portion related to a boom cylinder in a hydraulic actuator circuit including a load holding device according to a first embodiment of the present invention.

  In FIG. 1, this hydraulic actuator circuit includes a variable displacement hydraulic pump 2 driven by a motor (not shown), a hydraulic actuator (boom cylinder) 1 driven by hydraulic pressure discharged from the hydraulic pump 2, and a hydraulic pump. A control valve 4 for controlling the flow of pressure oil supplied from 2 to the boom cylinder 1, a pair of hydraulic lines 8a and 8b connecting the control valve 4 to the bottom side and the rod side of the boom cylinder 1, respectively, and a pilot A pump 3, a hydraulic pilot type operating lever device (hydraulic pilot operating means) 5 for generating a pilot pressure from the pressure oil discharged from the pilot pump 3 and switching the control valve 4, an operating lever device 5 and a control valve A pair of pilot pipes 7a connecting the four pressure receiving chambers 4a and 4b And 7b, has a tank 12 for storing hydraulic oil supplied to the hydraulic pump 2 and a pilot pump 3.

A load holding valve 6 is disposed between the bottom side of the boom cylinder 1 and the hydraulic pipe line 8 a, and the load holding valve 6 is attached on the outer wall of the cylinder of the boom cylinder 1. The load holding valve 6 includes a holding valve 13 and a check valve 14 that allows only the flow of pressure oil from the hydraulic line 8a to the boom cylinder 1. The holding valve 13 is connected to the pilot pipe line 7 a via the signal pressure port 128 and has a pressure receiving chamber 13 a that receives the pilot pressure from the hydraulic pilot operating lever device 5. Further, the holding valve 13 is held in the shut-off position when the operating lever of the operating lever device 5 is not operated (the pilot pressure from the operating lever device 5 is the tank pressure) and the control valve 4 is in the neutral position. When the control lever is operated to output pilot pressure to the pilot line 7a and the control valve 4 is switched from the neutral position, the opening area is changed in accordance with the pilot pressure and the main ports 111 and 112 are connected. The flow of pressure oil between the hydraulic line 8a and the bottom side of the boom cylinder 1 is controlled. The holding valve 13 has a check valve function that shuts off the flow of pressure oil from the bottom side of the boom cylinder 1 to the hydraulic pipe line 8a at the shut-off position.

The hydraulic actuator circuit of this embodiment includes a pressure control unit 11 provided between the pilot conduit 7a and hydraulic lines 8a, the pressure control unit 11, pressure in the hydraulic conduit 8a Is provided on the downstream side of the pressure control valve 9, and is controlled from the pressure control valve 9 to a hydraulic line. The check valve 10 allows only the flow of the pressure oil to the 8a and prevents the pressure from being transmitted from the hydraulic line 8a to the pressure control valve 9. The pressure control valve 9 is, for example, a pressure reducing valve. In this case, the pressure control valve 9 operates when the differential pressure between the pressure of the pilot line 7a and the pressure on the outlet side of the pressure control valve 9 becomes higher than the set pressure of the spring 9a. Is controlled (depressurized) so as to be the set pressure of the spring 9a. As a result, when the pressure in the hydraulic line 8a becomes substantially atmospheric pressure (0) and the pressure on the outlet side of the pressure control valve 9 becomes almost 0, the pressure in the pilot line 7a does not exceed the set pressure of the spring 9a. Is controlled (depressurized). The pressure control valve 9 may be a relief valve. In this case, the pressure in the hydraulic line 8a is lower than the set pressure of the spring 9a, and the pressure on the outlet side of the pressure control valve 9 is set by the spring 9a. When the pressure is lower than the pressure, the pilot pipe 7a is controlled so that the pressure in the pilot line 7a does not exceed the set pressure of the spring 9a.

  FIG. 2 is a side view showing an external appearance of a hydraulic excavator on which the load holding device of the hydraulic actuator circuit of the present invention is mounted.

  In FIG. 2, the excavator includes a lower traveling body 100, an upper swing body 101, and a front work machine 102. The lower traveling body 100 is provided with left and right traveling motors 50 and 56, and the traveling motors 50 and 56 rotate the crawler 100a to travel forward or backward. A swing motor 53 is mounted on the upper swing body 101, and the upper swing body 101 is rotated to the right or left with respect to the lower traveling body 100 by the swing motor 53. The front work machine 102 includes a boom 103, an arm 104, and a bucket 105. The boom 103 is moved up and down by the boom cylinder 1, and the arm 104 is moved to the dump side (opening side) or the cloud side (scraping side) by the arm cylinder 54. Operated. A load holding valve 6 is provided on the outer cylinder wall on the bottom side of the boom cylinder 1.

  The boom cylinder 1 supports the entire front work machine 102 (the boom 103, the arm 104, and the bucket 105), and the total load (the boom 103, the arm 104, and the bucket 105) of the front work machine 102 in the contraction direction of the boom cylinder 1. When the bucket 105 is loaded, the loaded load acts as a load. As a result, a load pressure is always present on the bottom side of the boom cylinder 1. In the present specification, such a bottom side of the boom cylinder 1 is referred to as a load side.

  When the operating lever of the operating lever device 5 is operated in the direction B in the figure to generate a pilot pressure in the pilot line 7a and the boom cylinder 1 is operated in the contracting direction, the load pressure on the bottom side of the boom cylinder 1 is hydraulic. It acts on the control valve 4 via the pipe line 8a. The control valve 4 adjusts the contraction speed of the boom cylinder 1 by controlling the discharge flow rate from the boom cylinder 1 while adjusting the pressure (back pressure of the boom cylinder 1). Such speed control of the hydraulic actuator is generally called meter-out control, and the control valve 4 has a meter-out opening area so that such meter-out control can be performed. Further, during meter-out control, a load pressure is always applied to the hydraulic line 8a. In this specification, such a hydraulic line 8a is referred to as a load side line.

  FIG. 3 is a diagram showing meter-out opening area characteristics of the holding valve 13 and the control valve 4 and their combined opening area characteristics. In the figure, the horizontal axis represents the pilot pressure (reference symbol Pi) output from the operating lever device 5 to the pilot pipe line 7a, and the vertical axis represents the opening area (reference symbol A). Further, the solid line X is the opening area characteristic of the load holding valve 6, the solid line Y is the meter-out opening area characteristic of the control valve 4, and the alternate long and short dash line Z is their combined opening area characteristic.

  In FIG. 3, the opening area characteristic X of the holding valve 13 indicates that when the pilot pressure Pi is in the range of 0 to Pi0, the opening area is 0, and until the pilot pressure Pi exceeds Pi0 and reaches Pi2, the pilot pressure Pi is As the pressure increases, the opening area increases. When the pilot pressure Pi exceeds Pi2, the opening area increases abruptly. When the pilot pressure Pi becomes Pi3 or higher, the opening area is set to the maximum Amax.

  The meter-out opening area characteristic Y of the control valve 4 is that when the pilot pressure Pi is in the range of 0 to Pi0, the opening area is 0. When the pilot pressure Pi exceeds Pi0, the opening increases as the pilot pressure Pi increases. The area is set to increase. However, the opening area of the control valve 4 is set to be smaller than the opening area of the holding valve 13.

The meter-out opening area of the control valve 4 and the opening area of the holding valve 13 and their combined opening area have the following relationship.
1 / A1 2 + 1 / A2 2 = 1 / A TOTAL 2 (1)
A1: Meter-out opening area of control valve
A2: Opening area of the holding valve
A TOTAL : Series synthetic opening area The synthetic opening area of the meter-out opening area of the control valve 4 and the opening area of the holding valve 13 can be obtained from the above relationship, and the opening of the holding valve 13 with respect to the pilot pressure Pi. When the area and the opening area of the control valve 4 change as described above, the characteristic (synthetic opening area characteristic) Z of the synthetic opening area is indicated by a one-dot chain line.

  The function of the pressure control valve 9 will be described with reference to FIG. In the figure, the horizontal axis represents the operation amount (stroke) of the operation lever of the operation lever device 5, that is, the lever operation amount (reference S), and the vertical axis represents the pilot pressure (reference Pi) generated in the pilot pipe line 7a.

  When the hydraulic line 8a is not bursting (breaking) and normal, the load pressure on the bottom side of the boom cylinder 1 always acts on the hydraulic line 8a (load side line) during the operation of the boom cylinder 1. The check valve 10 is kept closed (described later), and the pressure control valve 9 is inoperable. Therefore, the pilot line 7a functions as a normal pilot line, and a pilot pressure corresponding to the operation amount of the operation lever is generated in the pilot line 7a. A solid line G in FIG. 4 shows the relationship between the lever operation amount S and the pilot pressure Pi in the normal state. When the lever operation amount S is in the range of 0 to S0 (dead zone), the pilot Pi is 0. When the lever operation amount S exceeds S0, the pilot pressure Pi increases as the lever operation amount S increases. When the lever operation amount S reaches S2, which is slightly smaller than the maximum value Smax, the pilot pressure Pi becomes Pimax.

  When the hydraulic pipe line 8a bursts (described later), the pressure of the hydraulic pipe line 8a becomes atmospheric pressure (0), so that the pressure control valve 9 is operable. As a result, when the operating lever of the operating lever device 5 is operated in the direction B in the figure to generate the pilot pressure in the pilot pipe line 7a, if the pilot pressure tries to exceed the set value of the spring 9a, the pressure control valve 9 In operation, the pilot pressure is limited below the set value of the spring 9a. As a result, the relationship between the lever operation amount S and the pilot pressure Pi changes as indicated by a solid line H. In the figure, Pi1 is a set value of the spring 9a of the pressure control valve 9, and S1 is a lever operation amount value corresponding to the pilot pressure of the set value Pil. As shown in this figure, until the lever operation amount S reaches S1, the pilot pressure Pi changes as in the case of the solid line G. When the lever operation amount reaches S1 and the pilot pressure increases to Pil, the pressure control is performed. Valve 9 is actuated to limit further increase in pilot pressure.

  Returning to FIG. 3, A1 is the opening area of the holding valve 13 when the pilot pressure is limited to Pil. As described above, in Europe, as a performance of the holding valve 13 when the holding valve 13 is provided in the load side pipe line 8a of the boom cylinder 1, a test load that is 1/2 of the actual vehicle rated lifting capacity is applied according to ISO8643. The operating speed of the load is set to 200 mm / sec, and the cylinder speed (load dropping speed) when the load side pipe 8a of the boom cylinder 1 is burst is twice the operating speed (400 mm / sec). ) Is required. The value of the combined opening area of the holding valve 13 and the control valve 4 at the pilot pressure Pi1 is set so that the operating speed is 200 mm / sec, and the opening area A1 is twice that at the burst of the load side pipe line 8a (400 mm / sec). (sec) is set to obtain a falling speed of less than (sec).

  FIG. 5 is a hydraulic circuit diagram showing a specific configuration of the holding valve 13.

  In FIG. 5, the holding valve 13 has a housing 130 having the main ports 111 and 112 and the signal pressure port 128, and the main port 111 is directly connected to the bottom side of the boom cylinder 1, and the main port 112 is an actuator. The signal pressure port 128 is connected to the hydraulic pilot operating lever device 5 via the pilot line 7a.

  In the housing 130, a poppet valve body 113 as a main valve, a spool valve body 114 as a pilot valve that is operated by a pilot pressure from the operation lever device 5 to operate the poppet valve body 113, and functions of an overload relief valve And a small relief valve 115 having.

  In the housing 130, a cylinder connection chamber 116 connected to the main port 111, a pipe connection chamber 117 connected to the main port 112, and a back pressure chamber 118 are provided, and the poppet valve body 113 as a main valve is provided in the back. The pressure chamber 118 is slidably disposed in the housing 130 so as to receive the pressure of the pressure chamber 118 on the back surface and to block and communicate between the cylinder connection chamber 116 and the pipe connection chamber 117. The poppet valve body 113 is provided with a throttle passage 119 for controlling the passage amount of pilot pressure oil flowing out from the cylinder connection chamber 116 to the back pressure chamber 118. In the back pressure chamber 118, a spring 128 that holds the poppet valve body 113 in the illustrated blocking position is disposed.

Further, pilot passages 120a, 120b, and 120c are formed in the housing 130, and the back pressure chamber 118 and the pipe connection chamber 117 are connected to each other via the pilot passage 120a, the spool valve body 114, and the pilot passage 120b. The connection chamber 116 and the pipe connection chamber 117 are connected via the pilot passage 120c, the spool valve body 114, and the pilot passage 120b. The spool valve body 114 is formed with a first variable throttle 114a that controls communication between the pilot passage 120a and the pilot passage 120b, and a second variable throttle 114b that controls communication between the pilot passage 120c and the pilot passage 120b. ing. A spring 121 for setting an initial valve opening force of the spool valve body 114 is provided at the valve closing direction operating end of the spool valve body 114, and the valve opening direction operating end of the spool valve body 114 is controlled by the operation lever device 5. A pressure receiving chamber 122 through which the pilot pressure is guided through the pilot pipe line 129 is provided, and the amount of movement of the spool valve body 114 depends on the balance between the control force by the pilot pressure guided to the pressure receiving chamber 122 and the biasing force of the spring 121. The opening areas of the first and second variable throttle portions 114a and 114b of the spool valve body 114 change according to the amount of movement, and the pilot flow rate is cut off, communicated and controlled. The pressure receiving chamber 122 corresponds to the pressure receiving chamber 13a of FIG. The end of the spool valve body on which the spring 121 is disposed is connected to the tank 12 via drain passages 123 and 124 in order to make the movement of the spool valve body 114 smooth.

  FIG. 6 is a view showing the opening area characteristics of the first and second variable throttle portions 114a and 114b of the pilot valve (spool valve body 114) and the main valve (poppet valve body 113) in the holding valve 13 shown in FIG. is there. In the figure, the horizontal axis represents the pilot pressure (reference symbol Pi) output from the operating lever device 5 to the pilot pipe line 7a, and the vertical axis represents the opening area (reference symbol A). The solid line C is the opening area characteristic of the main valve (poppet valve body 113), the solid line D is the opening area characteristic of the second variable throttle part 114b, and the solid line E is the opening area characteristic of the first variable throttle part 114a. is there.

  In FIG. 6, when the pilot pressure Pi is in the range of 0 to Pi0, the first and second variable throttle portions 114a and 114b of the spool valve body 114 are closed. Further, since the first variable throttle portion 114a is closed, the pressure in the back pressure chamber 118 does not decrease, and the poppet valve body 113 is also closed. When the pilot pressure Pi exceeds Pi0, the second variable throttle portion 114b of the spool valve body 114 starts to open as indicated by the solid line D, and when the pilot pressure Pi further increases, the second variable throttle portion increases as the pilot pressure Pi increases. The opening area of 114b increases. When the pilot pressure Pi further increases and exceeds Pi2, the first variable throttle portion 114a of the spool valve body 114 starts to open as indicated by the solid line E, and when the pilot pressure Pi reaches Pi3, the first and second variable throttle portions. The opening areas of 114a and 114b are maximized. As described above, when the opening areas of the first and second variable throttle portions 114a and 114b change, the first variable throttle portion 114a is closed until the pilot pressure Pi reaches Pi2, so that the pressure in the back pressure chamber 118 is increased. The poppet valve body 113 is still closed. When the pilot pressure Pi reaches Pi2 and the first variable throttle 114a starts to open, the back pressure chamber 118 communicates with the main port 112 via the first variable throttle portion 114a, and the first variable throttle portion 114a extends from the back pressure chamber 118. Then, a flow of pressure oil that reaches the tank 12 via the main port 112, the hydraulic line 8a shown in FIG. 1, and the control valve 4 occurs, and the pressure in the back pressure chamber 118 decreases. For this reason, as shown by the solid line C, when the poppet valve body 113 starts to open and the pilot pressure Pi further increases, the opening area of the poppet valve body 113 increases to one unit and becomes the maximum.

  The opening area of the holding valve 13 is the sum of the opening areas of the first and second variable throttle portions 114a and 114b and the spool valve body 113 represented by solid lines E, D, and C, and the characteristics thereof are indicated by a one-dot chain line X. It becomes like this. The opening area characteristic X of the holding valve 13 shown in FIG. 3 shows the characteristic of the alternate long and short dash line X thus obtained.

  The housing 130 is also provided with a relief passage 120e located on the entry side of the small relief valve 115 and a control passage 120f located on the exit side. The relief passage 120e is connected to the cylinder connection chamber 116, and the control passage 120f is It is connected to the tank 12 via a drain passage 124. Further, the control passage 120f is provided with a throttle 125 which is a pressure generating means, the signal passage 127 branches from between the small relief valve 115 and the throttle 125, and the pressure generated in the throttle 125 is spooled via the signal passage 127. The valve body 114 is guided to the pressure receiving chamber 126 provided at the valve opening direction operation end.

  When an excessive external force acts on the boom cylinder 1 and the cylinder connection chamber 116 becomes high pressure, the pressure in the relief passage 120e rises, the small relief valve 115 opens, and pressure oil flows into the control passage 120f provided with a throttle. As a result, the pressure of the signal passage 127 rises, this pressure acts on the pressure receiving chamber 126, moves the spool valve body 114 with a full stroke, and fully opens the first and second variable throttle portions 114a and 114b. At the same time, the poppet valve body 113 is opened. As a result, the high pressure oil generated by the external force is discharged to the tank by an overload relief valve (not shown) provided in the hydraulic line 8a to prevent the equipment from being damaged.

  The operation of the present embodiment configured as described above will be described.

1) During boom raising operation (when pressure oil is supplied to the bottom side of the boom cylinder 1)
When the operating lever device 5 is operated in the direction A in the figure, a pilot pressure corresponding to the lever operation amount is generated in the pilot pipe line 7b, and the pilot pressure is supplied to the pressure receiving portion 4b of the control valve 4, and the control valve 4 is shown in the figure. Switch to the right position. When the control valve 4 is switched to the right position in the figure, the pressure oil discharged from the hydraulic pump 2 passes through the control valve 4, the hydraulic pipe line 8 a and the holding valve 13 and the check valve 14 provided in the load holding valve 6. It is supplied to the bottom side of the boom cylinder 1. The pressure oil on the rod side of the boom cylinder 1 is discharged to the tank 12 via the hydraulic line 8 b and the control valve 4. At this time, since the pressure (load pressure) on the bottom side of the boom cylinder 1 acts on the inside of the hydraulic pipe line 8a and becomes high pressure, the check valve 10 is closed, and the high pressure in the hydraulic pipe line 8a is increased. There is no transmission to the control valve 9.

2) During boom lowering operation (when hydraulic oil is discharged from the bottom side of the boom cylinder 1)
When the operation lever device 5 is operated in the direction B in the figure, a pilot pressure corresponding to the lever operation amount is generated in the pilot pipe line 7a, and the pilot pressure is applied to the pressure receiving portion 4a of the control valve 4 and the pressure receiving portion 13a of the holding valve 13. Supplied. The control valve 4 is switched to the left position in the figure by the pilot pressure, and the pressure oil discharged from the hydraulic pump 2 is supplied to the rod side of the boom cylinder 1 via the control valve 4 and the hydraulic line 8b. The holding valve 13 is opened by the pilot pressure applied to the pressure receiving portion 13 a, and the pressure oil on the bottom side of the boom cylinder 1 is discharged to the tank 12 through the holding valve 13 and the control valve 4. At this time, the opening areas of the holding valve 13 and the control valve 4 are as shown by characteristics X and Y in FIG. As a result, the synthetic opening surface changes in accordance with the lever operation amount of the operation lever device 5, and the speed can be adjusted while controlling the discharge flow rate. Also at this time, the pressure (load pressure) on the bottom side of the boom cylinder 1 acts in the hydraulic pipe line 8a, the pressure is relatively high, and the check valve 10 is closed. Therefore, the high pressure in the hydraulic line 8 a is not transmitted to the pressure control valve 9. Further, since the check valve 10 is closed, the pressure control valve 9 is inoperable, and a pilot pressure corresponding to the operation amount of the operation lever as shown by a solid line G in FIG. The boom can be lowered as the operation lever is operated.

3) When the load pressure is maintained When the load pressure on the bottom side of the boom cylinder 1 is high as in the case of holding the suspended load with the control valve 4 in the neutral position without operating the operation lever device 5, The holding valve 13 is in the shut-off position described above, and the load pressure on the bottom side of the boom cylinder 1 is held by the check valve function of the hold valve 13 and the check valve 14 in the shut-off position, thereby reducing the leak amount.

4) When the hydraulic line 8a bursts during the boom lowering operation During the boom lowering operation (normal), the holding valve 13 and the control valve 4 are opened as described above, and the boom cylinder 1 is connected to the hydraulic line 8a. While adjusting the pressure (load pressure) on the bottom side, the discharge flow rate is controlled according to the combined opening surface of the holding valve 13 and the control valve 4 to adjust the speed. Under such circumstances, in the unlikely event that the hydraulic line 8a bursts, the pressure in the hydraulic line 8a drops to almost atmospheric pressure and the check valve 10 opens. As a result, even when the pressure control valve 9 is activated, the lever operation amount of the operation lever is larger than S1 in FIG. 4, and the pilot pressure generated in the pilot line 7a is higher than the set value Pil, the pilot pressure is As shown in FIG. 4, the pressure is controlled (depressurized) so as not to exceed the pressure of Pi1 which is the set value of the spring 9a. As a result, the opening area of the holding valve 13 is limited to a small value of A1 corresponding to the pilot pressure Pil as shown in FIG. 3, and the cylinder speed (load dropping speed) is kept at a safe speed specified in ISO8643. Can be secured.

  As described above, according to the present embodiment, the pressure control valve 9 does not operate when the hydraulic line 8a that is the load side line is not bursting, and the output pressure (pilot pressure) of the operation lever device 5 is The pressure is directly input to the pressure receiving portion 4a of the control valve 4 and the pressure receiving portion 13a of the holding valve 13, and the speed control of the boom cylinder 1 can be performed according to the operation of the operation lever of the operation lever device 5.

On the other hand, when the hydraulic line 8a bursts, the pressure in the hydraulic line 8a drops to almost atmospheric pressure, so that the pressure control valve 9 operates and the pilot pressure generated in the pilot line 7a is the set value of the spring 9a. Control (pressure reduction) is performed so as not to exceed Pi1 and, accordingly, the opening area of the holding valve 13 is limited to a small value of A1 corresponding to the pilot pressure Pi1 . As a result, the opening area of the holding valve 13 is surely reduced, controlling the falling speed of the load in a safe rate that prescribed in ISO8643, it is possible to ensure the safety of the work.

  Further, when the hydraulic pipe line 8a is not bursting normally, the high pressure in the hydraulic pipe line 8a does not act on the pressure control valve 9, so the configuration on the operation side of the holding valve 13 including the pressure control valve 9 is inexpensive and low-pressure specification. Since only the pressure control valve 9 and the check valve 10 are provided, the configuration is relatively simple, and the load holding device can be made inexpensive and compact.

  Further, since the holding valve 13 is configured to be fully opened when the pilot pressure exceeds a predetermined range Pi0 to Pi2 including Pi1, which is a set value, in the range where the pilot pressure exceeds the predetermined range Pi0 to Pi2, The meter-out opening area of the control valve 4 dominates the meter-out flow rate characteristic obtained by the combined opening area of the control valve 4 and the holding valve 13, and the opening area of the holding valve 13 has little influence. As a result, the holding valve 13 and the control for satisfying a desired meter-out flow rate characteristic (operability) and controlling the dropping speed of the load at the burst time of the hydraulic line 8a which is the load side line to a desired value. The opening area of the valve 4 can be easily set and tuned.

  In the embodiment of the present invention, the set value of the pressure control valve 9 (set value of the spring 9a) is fixed, but the set value of the spring 9b can be changed from the outside as shown in FIG. A variable pressure control valve 9A may be used. In this case, the magnitude of the pilot pressure Pi1 shown in FIG. 4 can be easily adjusted, and thereby the opening area A1 of the holding valve 13 shown in FIG. 3 can be easily adjusted.

It is a hydraulic circuit diagram which extracts and shows only a portion concerning a boom cylinder among hydraulic actuator circuits provided with a load holding device concerning a 1st embodiment of the present invention. 1 is a side view showing an external appearance of a hydraulic excavator in which a load holding device for a hydraulic actuator circuit according to the present invention is mounted. It is a figure which shows the opening area characteristic of a holding valve and a control valve, and those synthetic | combination opening area characteristics. It is a figure which shows the relationship between the lever operation amount of an operation lever apparatus, and pilot pressure. It is a hydraulic circuit diagram which shows the specific structure of a holding valve. It is a figure which shows the opening area characteristic of the 1st and 2nd variable throttle part of a pilot valve (spool valve body) and the main valve (poppet valve body) in the holding valve shown in FIG. It is a figure which shows the modification of a pressure control valve.

Explanation of symbols

1 Hydraulic actuator (boom cylinder)
2 Hydraulic pump 3 Pilot pump 4 Control valves 4a and 4b Pressure receiving chamber 5 Operation lever device (hydraulic pilot operating means)
6 Load holding valve 7a Pilot pipeline (load side pipeline)
7b Pilot pipelines 8a, 8b Hydraulic pipeline 9 Pressure control valve 10 Check valve 11 Pressure control unit 12 Tank 13 Holding valve 13a Pressure receiving chamber 14 Check valve 50, 56 Traveling motor 53 Turning motor 54 Arm cylinder 100 Lower traveling body 100a Crawler 101 Upper traveling body 102 Front work machine 103 Boom 104 Arm 105 Buckets 111, 112, 128 Input / output port 113 Poppet valve body 114 Spool valve body 115 Small relief valve 116 Cylinder connection chamber 117 Piping connection chamber 118 Back pressure chamber 119 Throttle passage 120a, 120b, 120c Pilot passage 120e Relief passage 120f Control passage 121 Spring 122 Pressure receiving chamber 123, 124f Drain passage 127 Signal passage 129 Pilot conduit 130 Housing

Claims (2)

  1. A hydraulic pump and a pilot pump;
    A hydraulic actuator driven by the hydraulic pressure discharged from the hydraulic pump;
    A control valve for controlling pressure oil supplied from the hydraulic pump to the hydraulic actuator and pressure oil discharged from the hydraulic actuator;
    Pilot operating means for generating pilot pressure from the pressure oil discharged by the pilot pump and switching the control valve;
    A hydraulic actuator having a pair of hydraulic pipes connecting the control valve and the hydraulic actuator, wherein one of the pair of hydraulic pipes is a load side pipe connected to a load side of the hydraulic actuator In a circuit load holding device,
    A holding valve provided between a load side of the hydraulic actuator and the load side conduit, and having a pressure receiving portion to which a pilot pressure from the hydraulic pilot operating means is guided, and a pilot guided to the pressure receiving portion When the pressure increases , the opening area changes so as to increase , and the pilot pressure becomes a first opening area that is smaller than a maximum opening area at a predetermined first pilot pressure, and the pilot pressure is A holding valve set to maximize the opening area at a second pilot pressure greater than the first pilot pressure;
    A pilot pressure connected to the pressure receiving portion of the holding valve is guided to the pressure receiving portion when the hydraulic pilot operating means switches the control valve so as to discharge the hydraulic oil of the hydraulic actuator to the load side pipe line. A pilot line,
    Pressure that is provided between the pilot line and the load side line, and that controls the pressure of the pilot line not to be higher than the first pilot pressure when the pressure of the load side line becomes a predetermined value or lower. A load holding device comprising a control valve.
  2. The load holding device for a hydraulic actuator circuit according to claim 1,
    A load holding device, further comprising a check valve provided between the pressure control valve and the load side pipe and blocking transmission of pressure from the load side pipe to the pressure control valve.
JP2006213526A 2006-08-04 2006-08-04 Load holding device for hydraulic actuator circuit Expired - Fee Related JP4890147B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2006213526A JP4890147B2 (en) 2006-08-04 2006-08-04 Load holding device for hydraulic actuator circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2006213526A JP4890147B2 (en) 2006-08-04 2006-08-04 Load holding device for hydraulic actuator circuit

Publications (2)

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JP2008039042A JP2008039042A (en) 2008-02-21
JP4890147B2 true JP4890147B2 (en) 2012-03-07

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IT201600106112A1 (en) * 2016-10-21 2018-04-21 Atlantic Fluid Tech S R L Hose breaking device
EP3557083A1 (en) 2018-04-16 2019-10-23 Atlantic Fluid Tech S.r.l. Tube rupture protection device
EP3599383A1 (en) 2018-07-27 2020-01-29 Atlantic Fluid Tech S.r.l. Actuator control device

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SE534272C2 (en) * 2009-06-18 2011-06-28 Kurt Palmloef SAFETY-vALVE
KR101134007B1 (en) 2009-07-21 2012-04-05 엠에스 주식회사 Hydraulic cylinder pressure control device of brake pad makingmachine
DE102011014685A1 (en) * 2011-03-22 2012-09-27 Linde Material Handling Gmbh Hydraulic control valve device
CN102900731B (en) * 2012-10-31 2014-12-31 长沙中联消防机械有限公司 Hydraulic control system for emergency withdraw of arm support
CN103836021A (en) * 2014-03-24 2014-06-04 徐州重型机械有限公司 Balance combined valve, hydraulic lifting system and fire fighting truck

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JPH0341211A (en) * 1989-07-07 1991-02-21 Ishikawajima Harima Heavy Ind Co Ltd Bearing supporting device for rotating body
JPH0357507A (en) * 1989-07-26 1991-03-12 Kobe Steel Ltd Method for controlling meandering of plate under rolling
JP3919399B2 (en) * 1998-11-25 2007-05-23 カヤバ工業株式会社 Hydraulic control circuit
JP3915622B2 (en) * 2002-07-30 2007-05-16 コベルコ建機株式会社 Load holding device for hydraulic actuator circuit
JP2004232832A (en) * 2003-02-03 2004-08-19 Sumitomo (Shi) Construction Machinery Manufacturing Co Ltd Holding valve of construction machine

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IT201600106112A1 (en) * 2016-10-21 2018-04-21 Atlantic Fluid Tech S R L Hose breaking device
EP3312436A1 (en) * 2016-10-21 2018-04-25 Atlantic Fluid Tech S.r.l. Anti-rupture tube device
EP3557083A1 (en) 2018-04-16 2019-10-23 Atlantic Fluid Tech S.r.l. Tube rupture protection device
EP3599383A1 (en) 2018-07-27 2020-01-29 Atlantic Fluid Tech S.r.l. Actuator control device

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