JP2010180973A - Method and device for synchronizing plurality of cylinders - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the inclination of a heavy matter in lifting up. <P>SOLUTION: When a solenoid selector valve 8 is switched to a lift-up side, working oil 7 is supplied to a cap-side pressure chamber 3a, 3b of each hydraulic cylinder 1a, 1b by the same pressure through a cap-side oil supply line 11, branch lines 11a and 11b thereof and each cap-side pressure connecting line 15a, 15b to extend each hydraulic cylinder 1a, 1b according to the lower surface shape of the heavy matter 5 to a position contacting therewith. When all the hydraulic cylinders 1a and 1b contact with the lower surface of the heavy matter 5 to make a load act thereon, a pilot operation selector valve 24 is switched by pilot pressure raised in a selector valve pilot line 34 branched from the branch cap-side oil supply/discharge line 11a, and the working oil 7 distributed to the same flow rate by a flow branch/collection valve 30 is supplied to the cap-side pressure chamber 3a, 3b of each hydraulic cylinder 1a, 1b, and each hydraulic cylinder 1a, 1b is synchronously extended to lift up the heavy matter 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a synchronization method and apparatus for a plurality of hydraulic cylinders used to synchronize the operations of the plurality of hydraulic cylinders when a plurality of hydraulic cylinders are used to move one heavy object up and down, or when moved horizontally. It is about.

  When a heavy object such as a mold or a work having a large area is moved up and down or horizontally using a plurality of hydraulic cylinders as hydraulic actuators, the load of the heavy object is distributed to the plurality of hydraulic cylinders. In order to make a burden, it is necessary to synchronize the operation of the plurality of hydraulic cylinders.

  As a representative method for synchronizing the operations of the hydraulic cylinders as a plurality of hydraulic actuators of this type, as shown in FIG. 7, a plurality of hydraulic cylinders as hydraulic actuators from the hydraulic pump B, for example, When hydraulic oil (pressure oil) is supplied to the two hydraulic cylinders A1 and A2 via the switching valve C for controlling the extension operation and the contraction operation, the hydraulic oil is supplied to the hydraulic cylinders A1 and A2. For example, a method of controlling the flow rate to the same flow rate by using the flow collecting valve D and an extension operation and a contraction operation from the hydraulic pump B to the two hydraulic cylinders A1 and A2 as schematically shown in FIG. There is a method of supplying hydraulic oil at the same pressure through a switching valve C for control.

  In addition, four hydraulics arranged at each vertex of the quadrilateral as a hydraulic circuit that enables the synchronization of the stroke of each hydraulic cylinder and appropriate load distribution at the same time when moving and lifting the heavy load using a hydraulic cylinder as a hydraulic actuator The hydraulic oil supply pressure to the two hydraulic cylinders in one diagonal position among the cylinders and the hydraulic oil supply pressure to the two hydraulic cylinders in the other diagonal position are balanced, Among the two hydraulic cylinders at one diagonal position and the two hydraulic cylinders at the other diagonal position, at least one of the two hydraulic cylinders at the diagonal position has the same level of supply flow rate. A hydraulic circuit for supplying hydraulic oil has been proposed in the past.

  According to a hydraulic circuit having such a configuration, the stroke and the load distribution of each hydraulic cylinder can be synchronized at the same time during the lift-up and down operations of the heavy structure and the like by the four hydraulic cylinders ( For example, see Patent Document 1).

  In addition, a large heavy load is supported by a large number of fulcrum parts and maintained parallel by hydraulic pressure, that is, as a means for raising and lowering each fulcrum part in synchronism with each other, a plurality of fulcrum parts of the large heavy load are identical. Each hydraulic cylinder is supported as a hydraulic actuator having an effective area, and when the large heavy object is lifted, the same amount of hydraulic oil (without oil leakage from the hydraulic pump to the cap side (anti-rod side) of each hydraulic cylinder) (Pressure oil) is supplied, and each fulcrum is raised synchronously at a speed proportional to the amount of pressure oil supplied, and when the large heavy object is lowered, the back pressure of each hydraulic cylinder prevents the fulcrum from dropping rapidly. Then, the same amount of hydraulic oil is supplied from the hydraulic pump to the head side (rod side) of each hydraulic cylinder in the same manner as described above, and each fulcrum is tuned at a speed proportional to the supply amount of the hydraulic oil. Lowered Tuning lifting method for large heavy, characterized in that the the like has been conventionally proposed (e.g., see Patent Document 2).

  Further, in order to be able to drive a hydraulic jack as a hydraulic actuator serving as a plurality of loads in a synchronized state, a cylinder and a piston rod are respectively connected to the plurality of hydraulic jacks (loads). A double-acting hydraulic cylinder and pressure oil supply / discharge means for supplying and discharging hydraulic oil (pressure oil) to the hydraulic cylinder and driving it for an arbitrary number of strokes. Conventionally, there has been a hydraulic device that controls the amount of hydraulic oil supplied to and discharged from each hydraulic jack through each hydraulic cylinder to drive the hydraulic jacks in a synchronized state. Proposed.

  According to a hydraulic apparatus having such a configuration, the hydraulic jacks (loads) as all the hydraulic actuators described above are set by making the volumes of all the hydraulic cylinders constant and setting the number of strokes of all the hydraulic cylinders to be the same. It can be controlled in a synchronized state (for example, see Patent Document 3).

  Furthermore, as a synchronous control device that operates hydraulic cylinders as a plurality of hydraulic actuators simultaneously and in small increments, the same number of individual oil chambers as the plurality of hydraulic cylinders and individual pistons accommodated in the individual oil chambers Are connected to each other by a connecting member so that each individual piston can simultaneously advance and retreat by the same stroke. As a configuration in which each hydraulic cylinder is individually connected, the hydraulic oil supplied from the hydraulic pump is once sucked into each individual oil chamber of the oil supply cylinder and then supplied to each hydraulic cylinder. Thus, synchronous control of the hydraulic actuator is made so that the same amount of hydraulic oil can be supplied to each hydraulic cylinder at exactly the same amount per operation of the oil cylinder. Location has been conventionally proposed (e.g., see Patent Document 4).

  A hydraulic cylinder is arranged at each vertex of a quadrangle, a hydraulic cylinder located at an arbitrary vertex is defined as a first hydraulic cylinder, and second, third, and fourth hydraulic cylinders are determined sequentially in the clockwise direction on the basis of this. , The cap side (push side) pressure chambers of the first and second hydraulic cylinders, the head side (return side) pressure chambers of the second and third hydraulic cylinders, and the third and fourth hydraulic pressures. A configuration in which the cylinder cap side (push side) pressure chambers and the head side (return side) pressure chambers of the fourth and first hydraulic cylinders are connected to each other by separate pipes and are connected in a closed loop type. Furthermore, there has been conventionally proposed a heavy-weight support device having a configuration in which each of the hydraulic cylinders is supported by a hydraulic jack as an individual hydraulic actuator.

  According to the supporting device having such a configuration, it is possible to vary the piston stroke while keeping the hydraulic pressure of each hydraulic cylinder constant. Therefore, even if there is unevenness on the lower surface of the heavy object supported by each hydraulic cylinder, It is said that the hydraulic cylinder can be brought into contact with the lower surface of the heavy object (see, for example, Patent Document 5).

  A hydraulic cylinder as a plurality of hydraulic actuators is provided, a load is mounted on a mounting means connected to the hydraulic cylinder, and hydraulic pressure is supplied to the plurality of hydraulic cylinders via a hydraulic pump on the mounting plate. In a lift device that lifts and lowers a mounted object, a hydraulic system having a configuration in which a plurality of hydraulic pumps that supply hydraulic pressure to the plurality of hydraulic cylinders are connected to an output shaft of a single motor as a common drive source. Conventionally, a lift device has been proposed.

  According to the hydraulic lift device having such a configuration, each of the hydraulic pumps that supply the hydraulic pressure to the plurality of hydraulic cylinders is driven to rotate in synchronization with the output transmitted from the single motor via the output shaft. Since all the rotation speeds of the hydraulic pumps are the same, it is said that complete synchronization of the plurality of hydraulic cylinders can be obtained (see, for example, Patent Document 6).

  In a balanced synchronization method of an automobile vehicle mounting base in which a vehicle is lifted by a pair of pantograph type mechanisms forming a part of the vehicle mounting base, the pair of pantograph type mechanisms are connected by a synchronization shaft via a connectable clutch. In addition, the pair of pantograph mechanisms can be moved up and down by a cylinder mechanism serving as a hydraulic actuator, the clutch is connected to integrate the synchronization shaft, and the vehicle platform is lifted by the cylinder mechanism. When a twist occurs in the position of the pair of vehicle mounts attached to each of the pantograph type mechanisms in the vertical direction to cause a twist to rotate the cross section of the synchronous shaft in the previous period, the displacement of the twist is detected to detect the displacement There has been proposed a balanced synchronization method for an automobile vehicle mounting base that is controlled to correct the twist by a cylinder mechanism ( For example, refer to Patent Document 7).

JP 2005-214368 A JP-A-7-53190 JP-A-7-332309 JP 2000-27806 A JP 2000-255990 A JP-A-8-231195 Japanese Patent No. 3040567

  However, as shown in FIG. 7, the method of controlling the supply flow rate of the hydraulic oil to the plurality of hydraulic cylinders A1 and A2 to the same flow rate is the case where the same heavy load is always operated, that is, the hydraulic cylinders A1 and A2 If the tip end of the rod is connected to a heavy object or is always in contact with the same part of the heavy object, there will be no problem, but the hydraulic cylinders A1 and A2 are normally free. Thus, the following problems occur when the hydraulic rods A1 and A2 are brought into contact with the heavy rods that are to be operated each time.

  That is, for example, when lifting each heavy cylinder placed above the hydraulic cylinders A1 and A2 in an upward posture, the operation is distributed by the diversion valve D and supplied to the hydraulic cylinders A1 and A2. Since the oil supply flow rate is the same, the height positions of the upper end sides of the operating rods of the hydraulic cylinders A1 and A2 are always synchronized. However, as shown in FIG. 9 (a), the lower surface of the heavy load E to be lifted up with the required portion supported by the fixed base F is not horizontal, and is uneven or inclined. (The figure shows a case where the lower surface of the heavy object E has irregularities), the difference in height position between the support points (contact points) of the hydraulic cylinders A1 and A2 on the lower surface of the heavy object E If, for example, the support location of one hydraulic cylinder A1 on the lower surface of the heavy load E is lower than the support location of the other hydraulic cylinder A2, the hydraulic oil with the same supply flow rate is extended. Of the hydraulic cylinders A1 and A2 to be operated, even if the tip end side of the actuating rod of one hydraulic cylinder A1 is in contact with the lower surface of the heavy object E, the tip end side of the actuating rod of the other hydraulic cylinder A2 is in contact with the heavy object E Have There.

  At this time, when the heavy object E does not move only by the extension operation of the one hydraulic cylinder A1, the operation to the other hydraulic cylinder A2 is caused by the leakage of the hydraulic oil at the flow collecting valve D (see FIG. 7). Since the oil supply is gradually performed, as shown in FIG. 9B, the tip end side of the operating rod of the other hydraulic cylinder A2 slowly rises and eventually comes into contact with the lower surface of the heavy object E. become. Therefore, after that, it is considered that lift-up is performed in a state in which the posture of the heavy object E is held by the synchronized extension operation of the hydraulic cylinders A1 and A2, but the operation of the one hydraulic cylinder A1 is performed. There is a problem that a large time lag occurs after the rod tip side comes into contact with the lower surface of the heavy load E until the tip end side of the working rod of the other hydraulic cylinder A2 comes into contact with the lower surface of the heavy load E.

  On the other hand, when the heavy object E moves only by the extension operation of the one hydraulic cylinder A1, the distal end side of the operating rod of the one hydraulic cylinder A1 is connected to the heavy object E as shown in FIG. The one hydraulic pressure that extends and synchronizes with the other hydraulic cylinder A2 until the tip of the operating rod of the other hydraulic cylinder A2 comes into contact with the lower surface of the heavy object E after contacting the lower surface. The support portion of the one hydraulic cylinder A1 in the heavy object E is pushed up by the cylinder A1 in advance. Therefore, there arises a problem that the heavy object E lifted up by the hydraulic cylinders A1 and A2 is inclined.

  As shown in FIG. 8, according to the method in which the hydraulic oil is supplied to the plurality of hydraulic cylinders A1 and A2 at the same pressure, it becomes a lift-up target as shown in FIG. Even if there is a difference in height position between the support points of the hydraulic cylinders A1 and A2 on the lower surface of the heavy load E because the lower surface of the heavy load E is uneven or the lower surface is inclined, When the load of the heavy object E acts on the one hydraulic cylinder A1 when the tip end of the operating rod of the one hydraulic cylinder A1 comes into contact with the lower surface of the heavy object E in advance, the hydraulic pump B (FIG. 7), the entire amount of hydraulic oil sent out is supplied to the other hydraulic cylinder A2 where no load is applied. Therefore, the hydraulic oil is shown in FIG. 9 (B) with a relatively short time lag. Like Square operating rod distal end side of the hydraulic cylinder A2 is brought into contact with the lower surface of the heavy E of. However, in this case, the center of gravity of the heavy object E is deviated from the center position of each support portion by the respective hydraulic cylinders A1 and A2, and each hydraulic cylinder A1 is configured to supply hydraulic oil at the same pressure. When an unbalanced load is applied to A2 from the heavy object E, there is a problem that a couple acts when the heavy object E is supported by the hydraulic cylinders A1 and A2 to move up and down, and the heavy object E tilts. Arise.

  Since the hydraulic circuit described in Patent Document 1 basically equalizes the supply pressure of hydraulic oil to each hydraulic cylinder as a hydraulic actuator, the weight to be operated on each hydraulic cylinder. When an unbalanced load is applied from an object, the heavy object supported by each hydraulic cylinder is inclined similarly to the method shown in FIG.

  Since what is described in Patent Document 2 basically controls the supply flow rate of hydraulic oil supplied to each hydraulic cylinder as a hydraulic actuator, the operation amount of each hydraulic cylinder is the same. . Therefore, if the lower surface of a large heavy object that is supported by the hydraulic cylinders to be moved up and down has irregularities or the lower surface is inclined, the large weights of each hydraulic cylinder are similar to the method shown in FIG. When supporting an object, the large heavy object is inclined.

  The hydraulic device described in Patent Document 3 basically controls the supply flow rate of hydraulic oil supplied to each hydraulic jack as a hydraulic actuator to be the same, and controls the operation amount to be the same. Therefore, if the lower surface of the supported object supported by each of the hydraulic jacks is uneven or the lower surface is inclined, when the supported object is supported by each hydraulic jack, as in the method shown in FIG. In addition, the supported object is inclined.

  The synchronous control device described in Patent Document 4 basically has the same supply flow rate of hydraulic oil supplied to each hydraulic cylinder as a hydraulic actuator and the same operation amount. If the lower surface of the heavy-weight structure supported by each hydraulic cylinder is uneven or the lower surface is inclined, the large-weight structure is supported when the heavy-weight structure is supported by each hydraulic cylinder, as in the method shown in FIG. Inclination occurs in the heavy structure.

  The heavy load support device described in Patent Document 5 lifts a heavy load placed on the upper side of each hydraulic cylinder by an extension operation of each hydraulic jack provided individually on the lower side of each hydraulic cylinder. Even if any one of the hydraulic jacks precedes the other hydraulic jacks, the supporting load of each of the hydraulic cylinders provided above the respective hydraulic jacks and connected in a closed loop type can be made constant. However, at this time, the heavy object cannot be prevented from tilting.

  Further, in the heavy load support device disclosed in Patent Document 5, a hydraulic actuator that generates a driving force for lifting a heavy load is provided individually on the lower side of each hydraulic cylinder, not on each hydraulic cylinder. However, Patent Document 5 does not disclose any specific method for synchronizing the operation of each hydraulic jack as the hydraulic actuator.

  According to the hydraulic lift device disclosed in Patent Document 6, the hydraulic oil supplied to all hydraulic cylinders (oil) is fed and returned by the same amount, so that all the hydraulic cylinders can be expanded and contracted. Since the lower surface of the load supported by each hydraulic cylinder is uneven or the lower surface is inclined, the load is inclined when the load is supported by each hydraulic cylinder. There is a problem that it ends up.

  Moreover, the hydraulic lift device disclosed in Patent Document 6 requires the same number of hydraulic pumps as the hydraulic cylinders, and requires a coupling mechanism for coupling the hydraulic pumps to the output shaft of a single motor. Therefore, there is a problem that the device configuration becomes complicated.

  According to the balance synchronization method of the automobile vehicle mounting platform disclosed in Patent Document 7, in the state where the clutch on the synchronization shaft connecting the pair of pantograph mechanisms is released, each of the pantograph mechanisms is Each pantograph mechanism can be individually operated by the corresponding cylinder mechanism, so that each pantograph mechanism is individually lifted from a no-load state to a loaded state, thereby placing each pantograph mechanism on a mounting table. When the pantograph mechanism is lifted by the corresponding cylinder mechanism after the clutch on the synchronous shaft is connected, the synchronous shaft can be arranged at a position corresponding to the unevenness on the lower surface side of the vehicle. The displacement of the operation of each cylinder mechanism can be detected based on the torsion of the cylinder, and if this torsion of the synchronous shaft is detected, the change is detected. By controlling the operation of each cylinder mechanism so as to correct the torsion of the shaft, it is possible to synchronize the lift of the pair of pantograph mechanisms by each cylinder mechanism. Since it is necessary to provide the pantograph type mechanism, there is a problem that the apparatus configuration becomes complicated. In addition, because of the configuration in which the pantograph mechanisms are connected to each other by the synchronization shaft, the pantograph mechanism is limited to a pair arranged so as to be orthogonal to the longitudinal direction of the synchronization shaft, and has a support point of three points or more. There is a problem that it cannot be applied to the device. Furthermore, since the device configuration for detecting the twist direction and the amount of twist and controlling the respective cylinder mechanisms by feedback is required for the twist of the synchronous shaft, there is a problem that the device configuration is further complicated. .

  Therefore, the present invention has a simple configuration that does not require a sensor or circuit configuration for feedback control, and has a center of gravity from the center of each support location by a plurality of hydraulic cylinders, and a heavy object having unevenness and inclination on the lower surface. Even with heavy objects that are out of position, a plurality of hydraulic cylinders that allow a plurality of hydraulic cylinders to quickly operate a heavy object to be operated without tilting from the direction of expansion and contraction of each hydraulic cylinder. It is an object of the present invention to provide a synchronization method and apparatus.

  In order to solve the above-described problem, the present invention, corresponding to claim 1, starts the extension operation by supplying hydraulic oil at the same pressure to the cap-side pressure chambers of a plurality of hydraulic cylinders for moving heavy objects. Then, when the operating rods of all the hydraulic cylinders come into contact with the heavy objects and a load is applied to all the hydraulic cylinders, the hydraulic oil is supplied to the cap-side pressure chambers of all the hydraulic cylinders at the same flow rate to A method of synchronizing a plurality of hydraulic cylinders that synchronize the hydraulic cylinders to move the heavy objects is provided.

  According to claim 2, the hydraulic oil is supplied at the same pressure to the cap side pressure chambers of a plurality of hydraulic cylinders for moving heavy objects through a circuit capable of supplying the hydraulic oil at the same pressure. Supply and start the extension operation, then, the operating rods of all the hydraulic cylinders contact the above-mentioned heavy load and load is applied to all the hydraulic cylinders, so that it connects to the cap side pressure chamber of each hydraulic cylinder When the hydraulic oil pressure in the line is increased, the same amount of hydraulic oil is supplied to the cap-side pressure chamber of each hydraulic cylinder by switching the pilot operation switching valve using the increased pressure as the pilot pressure. Connect the circuit so that the hydraulic oil can be supplied to the cap-side pressure chambers of all the hydraulic cylinders at the same pressure and synchronize the hydraulic cylinders. It is not a method for synchronizing multiple hydraulic cylinders to move the weight thereof.

  In each of the above configurations, a plurality of hydraulic cylinders for moving heavy objects are used as hydraulic cylinders in an upward posture, and the operating rods of all the hydraulic cylinders contact the lower surface of the heavy objects and a load is applied to all the hydraulic cylinders. Then, the hydraulic oil supplied to the cap-side pressure chambers of all the hydraulic cylinders is made the same, and the hydraulic cylinders are extended in synchronization to lift up the heavy load.

  Further, in accordance with claim 4, a circuit that can supply hydraulic oil at the same pressure to the cap-side pressure chambers of a plurality of hydraulic cylinders for moving heavy objects, and the operating rods of all the hydraulic cylinders are weighted. A pilot operation switching valve capable of switching the pressure of hydraulic fluid rising in a line connected to the cap-side pressure chamber of each hydraulic cylinder as a pilot pressure when a load is applied to all the hydraulic cylinders in contact with an object And a synchronizer for a plurality of hydraulic cylinders comprising a circuit configured to supply hydraulic oil at the same flow rate to the cap-side pressure chamber of each hydraulic cylinder by the switching operation of the pilot operation switching valve; To do.

According to the present invention, the following excellent effects are exhibited.
(1) Supply hydraulic oil to cap side pressure chambers of a plurality of hydraulic cylinders for moving heavy objects at the same pressure to start the extension operation, and then the operating rods of all the hydraulic cylinders contact the heavy objects When a load is applied to all the hydraulic cylinders, the hydraulic oil is supplied to the cap-side pressure chambers of all the hydraulic cylinders at the same flow rate so that the hydraulic cylinders are synchronized to extend and move the heavy objects. The synchronization method of a plurality of hydraulic cylinders, more specifically, the same through a circuit capable of supplying hydraulic oil at the same pressure to the cap-side pressure chambers of a plurality of hydraulic cylinders for moving heavy objects The hydraulic oil is supplied under pressure to start the extension operation, and then the operating rods of all the hydraulic cylinders come into contact with the above-mentioned heavy load so that all the hydraulic cylinders are loaded. When the hydraulic oil pressure in the line connected to the cap-side pressure chamber of each hydraulic cylinder rises, the cap of each hydraulic cylinder is switched by switching the pilot operation switching valve using the increased pressure as the pilot pressure. Connect a circuit that can supply the same flow rate of hydraulic oil to the side pressure chambers, and supply the hydraulic oil to the cap side pressure chambers of all the hydraulic cylinders with the same amount of hydraulic oil. A method of synchronizing a plurality of hydraulic cylinders that are operated to extend in synchronization with each other to move the above-mentioned heavy load, and that hydraulic oil can be supplied to the cap-side pressure chambers of the plurality of hydraulic cylinders for moving the heavy loads at the same pressure. When each of the hydraulic cylinders and the operating rods of all the hydraulic cylinders come into contact with heavy objects and a load is applied to all the hydraulic cylinders, A pilot operation switching valve capable of switching the pressure of the hydraulic oil rising in the line connected to the cap side pressure chamber of the compressor as a pilot pressure, and the switching operation of the pilot operation switching valve to change the cap side pressure of each hydraulic cylinder. Since there is a synchronizer for a plurality of hydraulic cylinders having a configuration in which a hydraulic fluid is supplied to the chamber at the same flow rate, the contact points of the operating rods of the hydraulic cylinders in the heavy object to be moved Even if the positions of the hydraulic cylinders are displaced along the extending / contracting operation direction of each hydraulic cylinder, the time lag required to bring the operating rods of all the hydraulic cylinders into contact with the heavy objects can be reduced. Further, by bringing the operating rods of all the hydraulic cylinders into contact with heavy objects, the movement of the heavy objects can be quickly started in a state where the loads of the heavy objects are dispersed in the respective hydraulic cylinders. In addition, as described above, when there is a difference in the position of the hydraulic cylinder in the expansion / contraction operation direction between the contact points of the operating rods of the hydraulic cylinders in the heavy load, or the gravity center of the heavy load is in contact with the operating rods of the hydraulic cylinders. Even when an unbalanced load is applied to each hydraulic cylinder due to the displacement from the center of the location, the heavy load is The hydraulic cylinders can be moved in a state that prevents the hydraulic cylinders from tilting from the direction of expansion and contraction.
(2) Further, the apparatus for moving the heavy object without tilting from the expansion / contraction operation direction of each hydraulic cylinder can be constituted by a hydraulic circuit. Therefore, there is no need for a complicated mechanism for detecting a shift in the amount of movement between the contact points of heavy objects by each hydraulic cylinder, or a mechanism for individually feedback-controlling the operation amount of each hydraulic cylinder based on the shift. Therefore, the device configuration for synchronizing the plurality of hydraulic cylinders can be simplified.
(3) Moreover, since the hydraulic cylinders are positioned each time according to the shape of the heavy load immediately before the heavy load is moved by the synchronized extension operation, Even if the respective hydraulic rods are out of phase after the hydraulic cylinders are contracted, they can be used for the next heavy load movement without causing any problems.
(4) When a plurality of hydraulic cylinders for moving a heavy object are hydraulic cylinders in an upward posture, the operating rods of all the hydraulic cylinders contact the lower surface of the heavy object and a load is applied to all the hydraulic cylinders. By making the flow rate of hydraulic oil supplied to the cap side pressure chambers of all the hydraulic cylinders the same, the hydraulic cylinders are extended in synchronization and lifted up the heavy load, so that When lifting up with a hydraulic cylinder, there are irregularities on the lower surface of the heavy object, the lower surface is inclined, and the height positions are different at each support point by each hydraulic cylinder on the lower surface of the heavy object, Even if the center of gravity of the heavy load is deviated from the center of each support location by each hydraulic cylinder and an unbalanced load is acting on each hydraulic cylinder from the heavy load, It can be heavy to prevent in advance the possibility that inclines from stretching operation direction of the hydraulic cylinders.

It is a schematic diagram showing one embodiment of an apparatus used for a synchronizing method of a plurality of hydraulic cylinders of the present invention. FIG. 2 is a schematic diagram showing a state from when the heavy rod is lifted up using the apparatus of FIG. 1 until a working rod of each hydraulic cylinder is first extended and brought into contact with the heavy load. FIG. 2 is a schematic diagram showing a state in which operating rods of each hydraulic cylinder are extended and operated while supporting heavy objects with operating rods of all hydraulic cylinders when lifting heavy objects using the apparatus of FIG. 1. It is a schematic diagram which shows the state which lifts up a heavy load using the apparatus of FIG. 1, and hold | maintains this heavy load while lifting up. It is a schematic diagram which shows the state which lifts down a heavy article using the apparatus of FIG. It is a schematic diagram which shows the other form of implementation of this invention. It is a figure which shows the outline | summary of an example of the synchronization method of the conventional several hydraulic cylinder. It is a figure which shows the outline | summary of another example of the synchronization method of the conventional several hydraulic cylinder. FIG. 8 shows a case where a heavy object with unevenness on the lower surface is lifted up by the synchronization method of a plurality of hydraulic cylinders in FIG. 7, (a) is a heavy object in which the operating rod tip side of one hydraulic cylinder precedes the other hydraulic cylinder. (B) is a schematic diagram showing a state in which the tip of the operating rod of the other hydraulic cylinder comes into contact with the lower surface of the heavy load due to leakage of the flow collecting valve, FIG. 5 is a schematic diagram showing a state in which a heavy object is tilted by a prior lift of the heavy object by one hydraulic cylinder.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 to FIG. 5 show an application example in which a heavy object is moved up and down by a plurality of hydraulic cylinders arranged in the vertical direction as one embodiment of the method and apparatus for synchronizing a plurality of hydraulic cylinders of the present invention. Then, in a state where the heavy objects 5 to be operated are disposed above the two hydraulic cylinders 1a and 1b as a plurality of hydraulic cylinders, the distal ends of the operating rods 2a and 2b of all the hydraulic cylinders 1a and 1b The hydraulic oil (pressure oil) 7 is supplied from the hydraulic pump 6 to the cap side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b at the same pressure until it comes into contact with the lower surface of the object 5. Thereafter, the tip ends of the operating rods 2a, 2b of all the hydraulic cylinders 1a, 1b come into contact with the lower surface of the heavy object 5, so that the load of the heavy object 5 acts on all the hydraulic cylinders 1a, 1b. Then, the supply flow path (circuit) of the hydraulic oil 7 is switched so that the hydraulic oil 7 is supplied at the same flow rate to the cap-side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b. , 1b are synchronously extended by hydraulic oil 7 supplied at the same flow rate so that the heavy object 5 is lifted up.

  Specifically, as shown in FIG. 1 showing an apparatus used in the synchronization method of a plurality of hydraulic cylinders according to the present invention, the hydraulic pump 6 is lifted up by a heavy load 5 by the extension operation of the two hydraulic cylinders 1a and 1b. A P port of an electromagnetic switching valve 8 for switching the lifting and lowering of the heavy object 5 due to the contraction operation of the hydraulic cylinders 1a and 1b is connected via an oil supply line 9 provided with a pressure reducing valve 10. The electromagnetic switching valve 8 is a spring center type 4-port 3-position direction control valve that is normally ABR connected.

  One end of a cap side oil supply line 11 having a flow rate adjusting valve (pressure temperature compensation type flow rate adjusting valve) 12 with a check valve 13 is connected to the A port which is one load side port of the electromagnetic switching valve 8. It is. The other end side of the cap-side oil supply line 11 is branched into two branch cap-side oil supply lines 11a and 11b, and check valves 14a and 14b are provided at intermediate positions of the branch cap-side oil supply lines 11a and 11b. Are provided.

  Further, at the tip side of the branch cap side oil supply lines 11a, 11b, cap side pressure chambers 3a, 3b of the hydraulic cylinders 1a, 1b are provided with external pilot type pilot check valves 16a, 16b. They are individually connected via the side pressure chamber connection lines 15a and 15b.

  One end side of a head side oil supply / discharge line 17 provided with a flow rate adjustment valve (pressure temperature compensation type flow rate adjustment valve) 18 with a check valve 19 is connected to the B port which is the other load side port of the electromagnetic switching valve 8. It is. The head side pressure chambers 4a and 4b of the hydraulic cylinders 1a and 1b are connected in parallel to the other end side of the head side oil supply / discharge line 17 via individual head side pressure chamber connection lines 20a and 20b. It is.

  A tank 22 for hydraulic oil 7 is connected to the R port of the electromagnetic switching valve 8 via an oil return line 21. As a result, one solenoid of the electromagnetic switching valve 8 is excited to move the spool from the normal position to the right in the figure so that the A port communicates with the P port and the B port communicates with the R port. Is switched from the hydraulic pump 6 by the pressure reducing valve 10 on the oil supply line 9 and the hydraulic oil 7 guided to the P port of the electromagnetic switching valve 8 at a relatively low required pressure is supplied to the electromagnetic switching valve 8. Are supplied to the cap-side oil supply line 11 from the A port, and the flow rate is adjusted by the flow rate adjusting valve 12 on the cap-side oil supply line 11, and then each branch cap-side oil supply line 11a, 11b and each cap-side pressure chamber. The same pressure is supplied to the cap-side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b through the connection lines 15a and 15b. Note that the set pressure of the pressure reducing valve 10 is set to such an extent that even if the distal ends of the operating rods 2a and 2b of all the hydraulic cylinders 1a and 1b come into contact with the lower surface of the heavy object 5, the heavy object 5 does not lift up. It shall be.

  On the other hand, the other solenoid of the electromagnetic switching valve 8 is excited to move the spool from the normal position to the left in the figure so that the B port communicates with the P port and the A port communicates with the R port. When switched, the hydraulic oil 7 guided from the hydraulic pump 6 through the pressure reducing valve 10 on the oil supply line 9 to the P port of the electromagnetic switching valve 8 at the required pressure is transferred from the B port to the head side oil supply / discharge line 17. After the flow rate is adjusted by the flow rate adjusting valve 18, the same pressure is supplied to the head side pressure chambers 4 a and 4 b of the hydraulic cylinders 1 a and 1 b through the head side pressure chamber connection lines 20 a and 20 b. .

  Further, the oil supply branch line 23 is branched from a required location upstream of the installation position of the pressure reducing valve 10 in the oil supply line 9, and the downstream end of the oil supply line 23 is connected to the pilot operation switching valve 24. Connect to the P port. The pilot operation switching valve 24 is a normally closed spring center type 3 port 3 position direction control valve.

  The port A, which is the load side port of the pilot operation switching valve 24, includes a P port of the flow dividing valve 30, a counter balance valve 26 with a check valve 27 for an external pilot, and a flow rate adjustment valve (pressure temperature with a check valve 29). Compensation type flow rate adjusting valve) 28 is connected via an oil supply / discharge line 25 provided in order. A tank 22 a for hydraulic oil 7 is connected to the R port of the pilot operation valve 24 via another oil return line 31.

  One end of each of the two branch oil supply / discharge lines 32a and 32b is connected to the A port and the B port of the distribution flow valve 30, and the other end of each branch oil supply / discharge line 32a, 32b is connected to Required locations upstream of the installation positions of the pilot check valves 16a and 16b in the cap-side pressure chamber connection lines 15a and 15b, for example, the cap-side pressure chamber connection lines 15a and 15b and the branch cap-side oil supply The lines 11a and 11b are connected to each other at connection points.

  Further, the pilot-side oil supply line 11 is connected to one of the pilot ports 33a for switching the P port and the A port to communicate with each other by moving the spool from the normal position to the right in the figure by the pilot operation switching valve 24. Or a location where the check valve 14a is installed in one branch cap side oil supply line 11a, for example, a location upstream of the check valves 14a, 14b in each branch cap side oil supply line 11a, 11b. A first switching valve pilot line 34 which is branched from the upstream position is connected. The pilot pressure required to act on the one pilot port 33a to switch the spool of the pilot operation switching valve 24 causes the operating rods 2a and 2b of the hydraulic cylinders 1a and 1b to be in an unloaded state. The hydraulic oil 7 is made to be higher than the supply pressure of the hydraulic oil 7 to the cap side pressure chambers 3a and 3b, which is required when the hydraulic pump 6 is extended, and the hydraulic oil 7 is guided from the hydraulic pump 6 to the electromagnetic switching valve 8. The hydraulic cylinders 1a, 1b are within the range below the set pressure of the pressure reducing valve 10 provided on the oil supply line 9 and the heavy cylinders 7 are loaded on the hydraulic cylinders 1a, 1b. It is set so as to be lower than the supply pressure of the hydraulic oil 7 to the cap side pressure chambers 3a, 3b required for extending the operating rods 2a, 2b. That.

  Further, in order to reduce the burden on the hydraulic pump 6, an accumulator 35 is provided in the oil supply line 9 in the vicinity of the branch point of the oil supply branch line 23. Thus, as described above, the electromagnetic switching valve 8 is switched to the lift-up side, and the hydraulic oil 7 guided from the hydraulic pump 6 through the pressure reducing valve 10 at the required pressure is transferred from the A port of the electromagnetic switching valve 8 to the cap side. A state in which the oil is supplied at the same pressure to the cap-side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b through the oil supply line 11, the branch cap-side oil supply lines 11a and 11b, and the cap-side pressure chamber connection lines 15a and 15b. When the heavy load 5 is received on the upper side of the operating rods 2a, 2b of the hydraulic cylinders 1a, 1b and the load of the heavy load 5 acts on all the hydraulic cylinders 1a, 1b, One pilot port 33 of the pilot operation switching valve 24 passes through the first switching valve pilot line 34 from the branch cap side oil supply line 11a. In as pilot pressures stand, the spool of the pilot operated changeover valve 24 is P port and the A port from the normal position are to be switched so as to communicate. Therefore, when the pilot operation switching valve 24 is switched, the hydraulic oil 7 supplied from the hydraulic pump 6 and maintained at a high pressure by the accumulator 35 on the oil supply line 9 passes through the oil supply branch line 23 to the pilot. After being guided to the P port of the operation switching valve 24, it is supplied from the A port of the pilot operation switching valve 24 to the oil supply / discharge line 25. Therefore, after the high pressure hydraulic oil 7 supplied to the oil supply / discharge line 25 passes through the check valve 27 attached to the counter balance valve 26 on the oil supply / discharge line 25, the flow rate adjustment valve 28 adjusts the flow rate. After that, the hydraulic fluid 7 that is guided to the flow collecting valve 30 and distributed to the AB ports so that the flow becomes half the total flow rate of the hydraulic oil 7 at the flow collecting valve 30 is The oil is supplied to the cap side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b via the branch oil supply / discharge lines 32a and 32b and the cap side pressure chamber connection lines 15a and 15b, respectively. Therefore, in each of the hydraulic cylinders 1a and 1b, the operation rods 2a and 2b can be extended in synchronization with each other by the hydraulic oil 7 supplied at the same flow rate to the cap-side pressure chambers 3a and 3b. It is.

  At this time, the hydraulic fluid supplied from the pilot operation switching valve 24 to the cap-side pressure chamber connection lines 15a and 15b through the oil supply / discharge line 25, the divided flow valve 30, and the branch oil supply / discharge lines 32a and 32b. The supply pressure of 7 is not depressurized by the pressure reducing valve 10, and therefore, before the pilot operation switching valve 24 is switched to the PA connection state, the cap side oil supply line 11 and each branch cap side oil from the electromagnetic switching valve 8. Compared to the supply pressure of hydraulic oil 7 supplied to the cap side pressure chambers 3a, 3b of the hydraulic cylinders 1a, 1b through the supply lines 11a, 11b and the cap side pressure chamber connection lines 15a, 15b at the same pressure. Although the pressure is high, the branch cap side oil supply lines 11a and 11b are provided with check valves 14a and 14b, respectively. Backflow into the valve 8 side are also available prevented.

  In the pilot operation switching valve 24, the other pilot port 33b for switching the A port and the R port to communicate with each other by moving the spool to the left in the figure has a required portion of the head side oil supply / discharge line 17. For example, a second switching valve pilot line 36 that is branched from a position upstream of the flow rate adjusting valve 18 on the head side oil supply / discharge line 17 is connected. Further, a counter balance valve pilot line 37 and a check valve pilot line 38 are branched from required portions on the head side pressure oil supply / discharge line 17. The counter balance valve pilot line 37 is connected to a pilot port of the counter balance valve 26 on the oil supply / discharge line 25, and the check valve pilot line 37 is branched to connect each cap side pressure chamber connection line. The pilot check valves 16a and 16b are individually connected to the pilot ports of the pilot check valves 16a and 16b. Thus, as described above, the electromagnetic switching valve 8 is switched to the lift-down side, and the hydraulic oil 7 is supplied from the B port of the electromagnetic valve 8 to the head-side oil supply / discharge line 17 and each head-side pressure chamber connection line. When supplying the same pressure to the head side pressure chambers 4a and 4b of the hydraulic cylinders 1a and 1b through the hydraulic cylinders 20a and 20b, the pilot check valves 16a and 16b provided on the cap side pressure chamber connection lines 15a and 15b are used. The hydraulic oil 7 is prevented from being discharged from the cap side pressure chambers 3a, 3b of the hydraulic cylinders 1a, 1b and supplied to the head side pressure chambers 4a, 4b of the hydraulic cylinders 1a, 1b. That is, when the pressure of the hydraulic oil 7 in the head side oil supply / discharge line 17 increases, the second switching valve pilot line 36 and the counter balance valve pyro And trine 37, the check valve pilot line 38 are as pilot pressure stand. Therefore, the pilot operation switching valve 24 switches the spool from the normal position so that the A port and the R port communicate with each other by the pilot pressure guided to the other pilot port 33b via the second switching valve pilot line 36. It is done. The counter balance valve 26 allows the hydraulic oil 7 to flow from the distribution flow valve 30 side to the pilot operation switching valve 24 side through the oil supply / discharge line 25 by the pilot pressure introduced through the counter balance valve pilot line 37. It is made to operate to become. Further, the pilot check valves 16a and 16b on the cap side pressure chamber connection lines 15a and 15b are connected to the cap side pressures of the hydraulic cylinders 1a and 1b by the pilot pressure introduced through the check valve pilot line 37. The hydraulic oil 7 is allowed to flow from the chambers 3a, 3b to the branched oil supply / discharge lines 32a, 32b through the cap-side oil supply / discharge lines 15a, 15b.

  Therefore, at this time, the hydraulic oil 7 in the cap-side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b is divided into the cap-side pressure chamber connecting lines 15a and 15b, the branch oil supply / discharge lines 32a and 32b, and the collection. The pilot valve is switched to the A port of the pilot operation switching valve 24 through the flow valve 30, the check valve 29 attached to the flow rate adjustment valve 28 on the oil supply / discharge line 25, and the counter balance valve 26 in this order. The oil can be discharged from the R port of the valve 24 through the oil return line 31 to the tank 22a. Therefore, the hydraulic oil 7 is supplied from the B port of the electromagnetic switching valve 8 switched to the lift-down side through the head-side oil supply / discharge line 17 and the head-side pressure chamber connection lines 20a, 20b. With the supply of the same pressure to the head-side pressure chambers 4a and 4b, the hydraulic pressure cylinders 1a and 1b are gradually moved while preventing the heavy object 5 from falling by securing the back pressure with the counter balance valve 26. The heavy object 5 can be lifted down by being contracted.

  39 is a filter provided on the discharge side of the hydraulic pump 6, 40 is a check valve provided on the oil supply line 9, 41 is a relief valve connected to the oil supply line 9, and 42 is a relief valve connected to the oil supply / discharge line 25. , 43 are drain lines of the pilot check valves 16a, 16b. Reference numeral 44 denotes a fixed base for placing a heavy object 5 disposed above the hydraulic cylinders 1a and 1b.

  Although not shown, the hydraulic cylinders 1a and 1b are provided with sensors for detecting the stroke end on the expansion side and the stroke end on the contraction side. When one of the hydraulic cylinders 1a and 1b reaches the stroke end on the extension side when the hydraulic cylinders 1a and 1b are extended by the switching operation to the up side, based on the detection signal. Thus, the solenoid for switching the lift-up side of the electromagnetic switching valve 8 is demagnetized so that the spool of the electromagnetic switching valve 8 can be returned to the normal position. Further, when the electromagnetic switching valve 8 is switched to the lift-down side and the hydraulic cylinders 1a and 1b are contracted, any one of the hydraulic cylinders 1a and 1b is in a contraction stroke end. Is reached, the solenoid for switching the lift-down side of the electromagnetic switching valve 8 is demagnetized based on the detection signal so that the spool of the electromagnetic switching valve 8 can be returned to the normal position.

  In the case where the heavy object 5 to be operated is moved up and down by using the synchronizer for a plurality of hydraulic cylinders according to the present invention having the above-described configuration, as shown in FIG. 1, in advance, above the hydraulic cylinders 1a and 1b. The heavy object 5 is arranged, and a required portion of the heavy object 5 that does not interfere with the operating rods 2a and 2b of the hydraulic cylinders 1a and 1b is placed on and supported by the fixed base 44. In addition, the said heavy article 5 has an unevenness | corrugation and inclination in the lower surface (the figure shows the case where an unevenness | corrugation exists), for example, as shown in FIG. 1, among the said hydraulic cylinders 1a and 1b, It is assumed that the height position of the part supported by one hydraulic cylinder 1a is lower than the height position of the part supported by the other hydraulic cylinder 1b.

  In this state, when the heavy object 5 is lifted up, the electromagnetic switching valve 8 is switched to the lift-up side as shown in FIG. Thus, the hydraulic oil 7 guided from the P port to the A port of the electromagnetic switching valve 8 in a state where the pressure is reduced to the required pressure by the pressure reducing valve 10 on the oil supply line 9 from the hydraulic pump 6 is supplied to the cap side oil supply line. After the flow rate is adjusted by the flow rate adjusting valve 12 on 11, the cap side pressure chambers 3a of the hydraulic cylinders 1a and 1b via the branch cap side oil supply lines 11a and 11b and the cap side pressure chamber connection lines 15a and 15b, respectively. , 3b are supplied at the same pressure to start the extending operation of the operating rods 2a, 2b of the hydraulic cylinders 1a, 1b.

  When the extension operation of the operation rods 2a and 2b of the hydraulic cylinders 1a and 1b is started as described above, the operation rods 2a and 2b are substantially synchronized when the hydraulic cylinders 1a and 1b are not loaded. As described above, when there is a difference in height position between the support points of the hydraulic cylinders 1a and 1b on the lower surface of the heavy object 5, as shown by a solid line in FIG. The distal end side of the operating rod 2a of one hydraulic cylinder 1a comes into contact with the lower surface of the heavy object 5 prior to the other hydraulic cylinder 1b. As a result, the load of the heavy object 5 acts on the one hydraulic cylinder 1a.

  When the load of the heavy object 5 acts on the one hydraulic cylinder 1a, the hydraulic oil 7 supplied to the cap-side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b at the same pressure is supplied from the hydraulic pump 6 side. The entire amount newly introduced through the cap-side oil supply line 11 is supplied to the cap-side pressure chamber 3b of the other hydraulic cylinder 1b where the load of the heavy object 5 is not yet applied. For this reason, the operating rod 2b of the other hydraulic cylinder 1b is quickly extended, and a large time lag is not caused. As shown by a two-dot chain line in FIG. It comes into contact with the lower surface of the object 5. In this way, the time until the tip ends of the operating rods 2a, 2b of all the hydraulic cylinders 1a, 1b are brought into contact with the lower surface of the heavy object 5 is the flow rate adjusting valve 12 on the cap side oil supply line 11. What is necessary is just to set suitably via the flow volume adjustment of the hydraulic oil 7. FIG.

  When the operating rods 2a, 2b of all the hydraulic cylinders 1a, 1b are in contact with the lower surface of the heavy object 5 and a load is applied to all the hydraulic cylinders 1a, 1b as described above, the branch cap side As a result, the pressure of the hydraulic oil 7 in the oil supply lines 11a and 11b increases. As a result, as shown in FIG. 3, the pilot oil is supplied to the first switching valve pilot line 34 branched from the one branch cap side oil supply line 11a. Since the pressure rises and acts on one pilot port 33a of the pilot operation switching valve 24, the pilot operation switching valve 24 is switched to the PA connection state.

  When the pilot operation switching valve 24 is switched to the PA connection state, the hydraulic oil 7 guided to the pilot operation switching valve 24 through the oil supply line 9 and the oil supply branch line 23 with the pressure higher than that of the hydraulic pump 6 and the accumulator 35. After the flow rate is adjusted by the flow rate adjusting valve 28 on the oil supply / discharge line 25, the flow is adjusted to the divergence and flow control valve 30 and distributed by ½ flow rate, and then each branch oil supply / discharge line 32 a, 32 b and each flow rate is adjusted. The oil is supplied to the cap side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b via the cap side pressure chamber connection lines 15a and 15b, respectively. Accordingly, since the hydraulic oil 7 is supplied to the cap side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b at the same flow rate, the operating rods 2a and 2b of the hydraulic cylinders 1a and 1b are supplied. Synchronized extension operation is performed. Therefore, the heavy object 5 is lifted up by the hydraulic cylinders 1a and 1b without being inclined with respect to the expansion / contraction operation direction of the hydraulic cylinders 1a and 1b.

  In addition, since the extension operation of the hydraulic cylinders 1a and 1b is based on the supply of the hydraulic oil 7 having the same flow rate, each of the hydraulic cylinders 1a and 1b can be operated even when different loads are applied. The extension operations of the hydraulic cylinders 1a and 1b are kept in a synchronized state. Therefore, even if the center of gravity of the heavy load 5 is deviated from the center position of the respective support portions by the hydraulic cylinders 1a and 1b, an eccentric load acts on the hydraulic cylinders 1a and 1b from the heavy load 5. Even if this is the case, the possibility that the heavy object 5 is inclined from the direction of expansion and contraction of the hydraulic cylinders 1a and 1b is prevented.

  The hydraulic oil 7 discharged from the head side pressure chambers 4a and 4b of the hydraulic cylinders 1a and 1b when the hydraulic cylinders 1a and 1b are extended is connected to the head side pressure chamber connection lines 20a and 20b and the heads. After passing through the R port from the check valve 19 attached to the flow rate adjusting valve 18 on the side oil supply / discharge line 17 and the B port of the electromagnetic switching valve 8, the oil is recovered into the tank 22 through the oil return line 21.

  The ascending speed when the heavy load 5 is lifted up by the hydraulic cylinders 1a and 1b is appropriately set through the flow rate adjustment of the hydraulic oil 7 in the flow rate adjustment valve 28 on the oil supply / discharge line 25. do it.

  Thereafter, when one of the hydraulic cylinders 1a, 1b reaches the extension stroke end, the electromagnetic switching is performed as shown in FIG. 4 based on a detection signal of the extension stroke end from a sensor (not shown). The valve 8 is returned to the normal position. As a result, the P-port is blocked in the electromagnetic switching valve 8 and the ABR connection state is established. Therefore, the hydraulic oil that has acted on the cap-side oil supply line 11 and the branch cap-side oil supply lines 11a and 11b. When the supply pressure of the hydraulic oil 7 in the one branch cap side oil supply line 11a disappears, one of the pilot operation switching valves 24 is connected via the first switching valve pilot line 34. Since the pilot pressure acting on the pilot port 33a is no longer established, the pilot operation switching valve 24 is also returned to the normal position to be in the all-port block state.

  Accordingly, the supply of the hydraulic oil 7 to the cap-side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b is stopped, and the lift-up operation of the heavy object 5 by the hydraulic cylinders 1a and 1b is stopped. At this time, the load of the heavy object 5 is acting on the hydraulic cylinders 1a and 1b, but the discharge of the hydraulic oil 7 from the cap-side pressure chambers 3a and 3b is connected to the cap-side pressure chambers. Since it is blocked by the pilot check valves 16a and 16b on the lines 15a and 15b, the heavy object 5 is held in a lifted-up state.

  Next, when the heavy object 5 is lifted down, as shown in FIG. 5, the electromagnetic switching valve 8 is switched to the lift-down side. As a result, the flow rate of the hydraulic oil 7 guided from the hydraulic pump 6 through the oil supply line 9 to the electromagnetic switching valve 8 is adjusted by the flow rate adjusting valve 18 on the head-side oil supply / discharge line 17, and then each head-side pressure is adjusted. It becomes possible to supply to the head side pressure chambers 4a and 4b of the hydraulic cylinders 1a and 1b through the chamber connection lines 20a and 20b. However, at this time, the hydraulic oil 7 is discharged from the cap side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b by the pilot check valves 16a and 16b on the cap side pressure chamber connection lines 15a and 15b. Since it is blocked, the supply pressure of the hydraulic oil 7 in the head side oil supply / discharge line 17 is increased.

  When the supply pressure of the hydraulic oil 7 increases in the head-side oil supply / discharge line 17 as described above, a second switching valve pilot line 36 branched from the head-side oil supply / discharge line 17 is provided. Since the pilot pressure is generated in the counter balance valve pilot line 37 and the check valve pilot line 38, the pilot pressure of the second switching valve pilot line 36 acts on the other pilot port 33b. The operation switching valve 24 is switched to the AR connection state, and the counter balance valve 26 on the oil supply / discharge line 25 is switched so as to be able to flow from the side of the flow collecting valve 30. Further, the cap side pressure chamber connection lines 15a, Each pilot check valve 16a, 16b on 15b is connected to cap side pressure chamber 3a of each hydraulic cylinder 1a, 1b. It is switched to the ready discharge of the working fluid 7 from 3b.

  Accordingly, the hydraulic oil 7 is supplied to the head side pressure chambers 4a and 4b of the hydraulic cylinders 1a and 1b, and at the same time, the hydraulic oil 7 in the cap side pressure chambers 3a and 3b is supplied to the cap side pressure chambers. Pilot operation is switched through the connection lines 15a, 15b, the branch oil supply / discharge lines 32a, 32b, the distribution flow valve 30, the check valve 29 attached to the flow rate adjustment valve 28 on the oil supply / discharge line 25 and the counter balance valve 26. After leading to the A port of the valve 24, the hydraulic cylinders 1a, 1b are contracted to recover from the R port of the pilot operation switching valve 24 through the oil return line 31 to the tank 22a. The object 5 is gradually lifted down while the cylinder load is held by the counter balance valve 26.

  At this time, the amount of hydraulic oil discharged from the cap-side pressure chambers 3a and 3b of the hydraulic cylinders 1a and 1b is controlled by the flow dividing valve 30 so as to have the same flow rate. Therefore, since the contraction operation of the hydraulic cylinders 1a and 1b is synchronized, it is possible to prevent the heavy object 5 from being inclined from the contraction operation direction of the hydraulic cylinders 1a and 1b even when the heavy object 5 is lifted down. Is done.

  The descending speed when the heavy load 5 is lifted down by the hydraulic cylinders 1a and 1b may be appropriately set through the flow rate adjustment in the flow rate adjustment valve 18 on the head side oil supply / discharge line 17. Good.

  Thereafter, when one of the hydraulic cylinders 1a and 1b reaches the contraction stroke end, the electromagnetic switching valve 8 is set to the normal position based on a detection signal of the contraction stroke end from a sensor (not shown). Will be restored. As a result, the supply of hydraulic oil to the head-side oil supply / discharge line 17 via the electromagnetic switching valve 8 is stopped, so that the contraction operation of the hydraulic cylinders 1a and 1b is stopped. At the same time, no pilot pressure is generated in the second switching valve pilot line 36, the counter balance valve pilot line 37, and the check valve pilot line 38, so that the pilot operation switching valve 24 is in the normal position. The counter balance valve 26 on the oil supply / discharge line 25 and the pilot check valves 16a and 16b on the cap side pressure chamber connection lines 15a and 15b return to the initial positions. Therefore, the initial state is the same as shown in FIG.

  As described above, according to the synchronization method and apparatus for a plurality of hydraulic cylinders of the present invention, even if there is a difference in the height positions of the support portions of the hydraulic cylinders 1a and 1b on the lower surface of the heavy object 5, all the hydraulic cylinders 1a are used. , 1b, the time lag required to bring the tip side of the operating rods 2a, 2b into contact with the lower surface of the heavy object 5 can be reduced, so that the load of the heavy object 5 is distributed to the hydraulic cylinders 1a, 1b. The lift-up of the heavy object 5 can be started promptly. In addition, as described above, when there is a difference in the height position of the support portions of the hydraulic cylinders 1a and 1b on the lower surface of the heavy load 5, or the center of gravity of the heavy load 5 is from the center of the support portions by the hydraulic cylinders 1a and 1b. Even if an eccentric load is applied to the hydraulic cylinders 1a and 1b by the heavy load 5 due to the displacement, the heavy load 5 is operated to expand and contract by the hydraulic cylinders 1a and 1b. It is possible to move up and down while preventing the possibility of tilting from the direction.

  Further, the apparatus for moving the heavy object 5 up and down without tilting from the direction of expansion and contraction of the hydraulic cylinders 1a and 1b by the synchronized expansion and contraction of the hydraulic cylinders 1a and 1b is the hydraulic circuit shown in FIG. Can be configured. Therefore, a complicated mechanism for detecting the displacement of the height position of the supporting portion of the heavy load 5 by the hydraulic cylinders 1a and 1b and the operation amount of the hydraulic cylinders 1a and 1b based on the displacement are individually determined. Since a mechanism for feedback control is not required, the device configuration of the synchronization device for a plurality of hydraulic cylinders according to the present invention can be simplified.

  Further, in each of the hydraulic cylinders 1a and 1b, immediately before the heavy load 5 is lifted up by the extension operation of the respective operating rods 2a and 2b in synchronization, the upper end side of the operating rods 2a and 2b is placed on the lower surface of the heavy load 5. Since each of the operating rods 2a and 2b is positioned each time by pressing the cylinder, after the hydraulic cylinders 1a and 1b are contracted as shown in FIG. Even if there is a synchronization shift, that is, a phase shift between the actuating rods 2a and 2b, the next lifting operation of the heavy object 5 can be performed without causing any problem.

  Next, FIG. 6 shows an application example of the embodiment of FIGS. 1 to 5 as another embodiment of the present invention. In the configuration similar to that shown in FIG. Application example in which a plurality of hydraulic cylinders to be performed is replaced with two hydraulic cylinders 1a and 1b, and four hydraulic cylinders 1c, 1d, 1e, and 1f arranged at each vertex of a square are used. Is shown. For convenience of illustration, the four hydraulic cylinders 1c, 1d, 1e, and 1f are shown in a line in the drawing.

  That is, in the same configuration as shown in FIG. 1, two branch cap side oil supply lines 11 a, on the other end side of the cap side oil supply line 11 having one end connected to the A port of the electromagnetic switching valve 8, Instead of 11b, branch cap side oil supply lines 11c, 11d, 11e with three check valves 14c, 14d, 14e are connected in parallel.

  Of the branch cap side oil supply lines 11c, 11d, and 11e, the cap side pressures of the first hydraulic cylinder 1c and the second hydraulic cylinder 1d are provided downstream of the first branch cap side oil supply line 11c. The chambers 3c and 3d are connected in parallel via individual cap side pressure chamber connection lines 15c and 15d.

  A cap-side pressure chamber 3e of the third hydraulic cylinder 1e is connected to the second branch cap-side oil supply line 11d via a cap-side pressure chamber connection line 15e. Further, the cap side pressure chamber 3f of the fourth hydraulic cylinder 1f is connected to the third branch cap side oil supply line 11e via a cap side pressure chamber connection line 15f.

  The cap-side pressure chamber connection lines 15c, 15d, 15e, and 15f have individual pilot check valves 16c, 16d, 16e, and 15f, as with the cap-side pressure chamber connection lines 15a and 15b shown in FIG. 16f is provided.

  Further, the head-side pressure chamber 4c of each of the hydraulic cylinders 1c, 1d, 1e, and 1f is connected to the other end of the head-side oil supply / discharge line 17 having one end connected to the B port of the electromagnetic switching valve 8. , 4d, 4e, 4f are connected in parallel via individual head side pressure chamber connection lines 20c, 20d, 20e, 20f.

  Further, the other end side of one branch oil supply / discharge line 32a having one end connected to the A port of the flow collecting valve 30 similar to that shown in FIG. 1 is connected to the first branch cap side oil supply / discharge line 11c. Is connected to the downstream side of the check valve 14c.

  The other end of the other branch oil supply / discharge line 32b having one end connected to the B port of the flow collecting valve 30 is connected to the P port of another flow collecting valve 45, and The other ends of the two connecting oil supply / discharge lines 46a and 46b, each having one end connected to the A port and the B port, correspond to the second branch cap side oil supply line 11d and the third hydraulic cylinder 1e. Communicating with the cap-side pressure chamber connecting line 15e and the connecting portion between the third branch cap-side oil supply line 11e and the cap-side pressure chamber connecting line 15f corresponding to the fourth hydraulic cylinder 1f. It is configured to be connected.

  Further, the first switching valve pilot line 36 for connection to one pilot port 33a of the pilot operation switching valve 24 similar to that shown in FIG. 1 is checked in the first branch cap side oil supply / discharge line 11c. A branch is provided from a position upstream of the valve 14c. Further, the head side pressure oil supply to the pilot check valves 16c, 16d, 16e and 16f is similar to the pilot check valves 16a and 16b on the cap side pressure chamber connection lines 11a and 11b shown in FIG. A check valve pilot line 38 branched from the exhaust line 17 is connected.

  Other configurations are the same as those shown in FIG. 1, and the same components are denoted by the same reference numerals.

  In the case where the heavy object 5 to be operated is moved up and down using the synchronizer of the plurality of hydraulic cylinders of the present embodiment having the above-described configuration, it is previously placed above the hydraulic cylinders 1c, 1d, 1e, and 1f. The above-mentioned heavy load 5 is arranged, and necessary portions that do not interfere with the respective operating rods 2c, 2d, 2e, 2f are placed on and supported by the fixed base 44.

In this state, first, when the electromagnetic switching valve 8 is switched to the lift-up side as shown in FIG.
After the pressure is reduced to the required pressure by the pressure reducing valve 10 on the oil supply line 9 from the hydraulic pump 6, the hydraulic oil 7 guided to the cap side oil supply line 11 through the electromagnetic switching valve 8 is supplied to the first branch cap. From the side oil supply line 11c to the cap side pressure chambers 3c, 3d of the first and second hydraulic cylinders 1c, 1d via the cap side pressure chamber connection lines 15c, 15d, and the second branch cap side From the oil supply line 11d to the cap side pressure chamber 3e of the third hydraulic cylinder 1e via the cap side pressure chamber connection line 15e, and from the third branch cap side oil supply line 11e to the cap side pressure chamber connection line 15f. Then, the same pressure is supplied to the cap-side pressure chamber 3f of the third hydraulic cylinder 1f. Accordingly, the extension operation of the operation rods 2c, 2d, 2e, 2f of the hydraulic cylinders 1c, 1, 1e, 1f is started.

  Even if there is a difference in height position between the support positions of the hydraulic cylinders 1c, 1d, 1e, and 1f due to unevenness and inclination on the lower surface of the heavy object 5, the hydraulic cylinders 1c, 1d, When the actuating rods 2c, 2d, 2e, 2f of 1e, 1f come into contact with the lower surface of the heavy object 5 and a load is applied to the hydraulic cylinders 1c, 1d, 1e, 1f, the electromagnetic switching valve 8 The hydraulic oil 7 newly supplied from the side is distributed and supplied to the unloaded hydraulic cylinders 1c, 1d, 1e, and 1f that are not yet in contact with the lower surface of the heavy load 5, so that the unloaded hydraulic pressure is supplied. The extending operation of the cylinders 1c, 1d, 1e, and 1f is continuously performed. Similarly, when the next hydraulic cylinder 1c, 1d, 1e, 1f comes into contact with the lower surface of the heavy object 5 and a load is applied, the hydraulic oil 7 newly supplied from the electromagnetic switching valve 8 side is weighted. Since the supply to the remaining hydraulic cylinders 1c, 1d, 1e, and 1f that are not in contact with the object 5 and are in an unloaded state is repeated, all the hydraulic cylinders 1c, 1d, 1e, and 1f have a large time lag. It comes in contact with the lower surface of the heavy object 5 without.

  When all the hydraulic cylinders 1c, 1d, 1e, and 1f are in contact with the lower surface of the heavy article 5 and a load is applied to all the hydraulic cylinders 1c, 1d, 1e, and 1f as described above, The pressure of the hydraulic oil 7 in the cap side oil supply lines 11c, 11d, and 11e is increased, and as a result, it is branched from the first branch cap side oil supply line 11c in the same manner as shown in FIG. The pilot pressure standing in the first switching valve pilot line 34 acts on one pilot port 33a of the pilot operation switching valve 24, whereby the pilot operation switching valve 24 is switched to the PA connection state.

  When the pilot operation switching valve 24 is switched to the PA connection state, the hydraulic oil 7 guided to the pilot operation switching valve 24 through the oil supply line 9 and the oil supply branch line 23 with the pressure higher than that of the hydraulic pump 6 and the accumulator 35. Is led to the flow collecting valve 30 through the oil supply / discharge line 25 and is divided into ½ flow rate of the total supply flow rate by the flow collecting valve 30, and the operation of the ½ flow rate of one of the divided flow rates is performed. After the oil 7 passes through one branch oil supply / discharge line 32a and the first branch cap side oil supply line 11c, the first and second hydraulic cylinders 1c and 1d pass through the cap side pressure chamber connection lines 15c and 15d. Are supplied to the cap-side pressure chambers 3c and 3d at the same pressure. At the same time, the other half flow rate of the hydraulic oil 7 distributed by the flow collecting valve 30 is guided to the other flow collecting valve 45 through the other branch oil supply / discharge line 32b. Then, one of the hydraulic oils 7 distributed to each ¼ flow rate is further divided into one connection oil supply / discharge line 46a and the cap side pressure chamber connection line. 15e is supplied to the cap side pressure chamber 3e of the third hydraulic cylinder 1e, and the other 1/4 flow rate of the hydraulic oil 7 is supplied to the other connection oil supply / discharge line 46b and the cap side pressure chamber connection line 15f. Is supplied to the cap-side pressure chamber 3f of the fourth hydraulic cylinder 1f.

  Therefore, in each of the hydraulic cylinders 1c, 1d, 1e, and 1f, the extending operation in which the respective operating rods 2c, 2d, 2e, and 2f are synchronized is performed. In a state in which the load is dispersed and supported by 1c, 1d, 1e, and 1f, the hydraulic cylinders 1c, 1d, 1e, and 1f are lifted up in a state in which the possibility of tilting from the expansion / contraction operation direction is prevented. become.

  When the heavy object 5 is lifted up, due to the error of the flow collecting valve 45, the flow collecting valve 45 causes the cap side pressure chamber 3e of the third hydraulic cylinder 1f and the fourth hydraulic pressure to be increased. If the flow rate of the hydraulic oil 7 distributed to the cap-side pressure chamber 3f of the cylinder 1f is not exactly the same, there is a slight difference in the extension operation amounts of the third and fourth hydraulic cylinders 1e and 1f. While lifting the heavy object 5, there is a concern that the relative positions of the support parts by the third and fourth hydraulic cylinders 1e and 1f in the heavy object 5 may shift in the vertical direction. However, since the hydraulic oil 7 is supplied to the cap-side pressure chambers 3c and 3d of the first and second hydraulic cylinders 1c and 1d at the same pressure, the heavy object 5 is supplied as described above. Even if the relative positions of the support portions by the third and fourth hydraulic cylinders 1e and 1f slightly shift in the vertical direction during the lift-up, the first and second hydraulic cylinders 1c follow the shift. Since the vertical position of the support portion by 1d and 1d is automatically adjusted, the load of the heavy object 5 is supported in a state of being always distributed to the four hydraulic cylinders 1c, 1d, 1e, 1f. Will be maintained.

  Thereafter, when any one of the hydraulic cylinders 1c, 1d, 1e, and 1f reaches the extension stroke end, the above-described electromagnetic force is detected in the same manner as shown in FIG. 4 based on the detection signal of the extension stroke end from a sensor (not shown). Since the switching valve 8 is returned to the normal position, the supply of the hydraulic oil 7 to the cap side pressure chambers 3c, 3d, 3e, 3f of the hydraulic cylinders 1c, 1d, 1e, 1f is stopped, The lift-up operation of the heavy object 5 is stopped. At this time, the load of the heavy object 5 acts on the hydraulic cylinders 1c, 1d, 1e, and 1f, but the hydraulic oil 7 is discharged from the cap-side pressure chambers 3c, 3d, 3e, and 3f. Is blocked by the pilot check valves 16c, 16d, 16e, and 16f on the cap-side pressure chamber connection lines 15c, 15d, 15e, and 15f, so that the heavy object 5 is held in a lifted-up state.

  Next, when the heavy object 5 is lifted down, the electromagnetic switching valve 8 may be switched to the lift-down side, whereby the head side oil supply / discharge is performed from the hydraulic pump 6 as shown in FIG. The hydraulic oil is supplied to the head side pressure chambers 4c, 4d, 4e, and 4f of the hydraulic cylinders 1c, 1d, 1e, and 1f through the line 17 and branched from the head side oil supply / discharge line 17. The pilot operation switching valve 24 is switched to the AR connection state based on the pilot pressure on the second switching valve pilot line 36, the counter balance valve pilot line 37, and the check valve pilot line 38; Switching of the counter balance valve 26 on the supply / discharge line 25 and each pyrometer on the cap side pressure chamber connection lines 15c, 15d, 15e, 15f. The check valves 16c, 16d, 16e, and 16f are switched, and the hydraulic oil 7 is discharged from the cap-side pressure chambers 3c, 3d, 3e, and 3f of the hydraulic cylinders 1c, 1d, 1e, and 1f. Thus, the heavy load 5 is lifted down by the synchronized contraction operation of the hydraulic cylinders 1c, 1d, 1e, and 1f. At this time, the heavy load 5 is moved to the hydraulic cylinders 1c, 1d, and 1e. , 1f can be prevented from being tilted from the direction of contraction operation.

  Thereafter, when one of the hydraulic cylinders 1c, 1d, 1e, and 1f reaches the contraction side stroke end, the electromagnetic switching valve 8 is set to normal based on a detection signal of the contraction side stroke end from a sensor (not shown). Return to position. As a result, the contraction operation of the hydraulic cylinders 1c, 1d, 1e, and 1f is stopped, the second switching valve pilot line 36, the counter balance valve pilot line 37, and the check valve pilot line 38. When the pilot pressure is not established, the pilot operation switching valve 24 is returned to the normal position, the counter balance valve 26 on the oil supply / discharge line 25, and the cap side pressure chamber connection lines 15c, 15d, 15e. , 15fb, the pilot check valves 16c, 16d, 16e, 16f are returned to the initial positions, so that the initial state is the same as that shown in FIG.

  As described above, according to the present embodiment, even if there is a difference in the height positions of the support portions of the hydraulic cylinders 1c, 1d, 1e, and 1f on the lower surface of the heavy article 5, all the hydraulic cylinders 1c, 1d, The tip ends of the actuating rods 2c, 2d, 2e, 2f of 1e, 1f can be brought into contact with the lower surface of the heavy object 5, and the time lag at that time can be reduced, so that the hydraulic cylinders 1c, 1d , 1e, 1f, the lifting of the heavy object 5 in a state where the load of the heavy object 5 is dispersed can be started promptly. Therefore, the same effect as that of the embodiment of FIGS. 1 to 5 can be obtained.

  The present invention is not limited only to the above-described embodiments, and a switching operation is performed between lift-up and lift-down of the heavy object 8 to be moved by each hydraulic cylinder 1a, 1b or 1c, 1d, 1e, 1f. And by operating the switching valve to the lift-up side, the cap-side pressure chambers 3a, 3b or 3c, 3d, 3e of the hydraulic cylinders 1a, 1b or 1c, 1d, 1e, 1f, A hydraulic circuit capable of supplying hydraulic oil 7 to 3f at the same pressure, and operating rods 2a, 2b or 2c, 2d, 2e, 2f of all the hydraulic cylinders 1a, 1b or 1c, 1d, 1e, 1f. Each of the cap side pressure chambers 3a, 3 is brought into contact with the heavy load 5 to be moved and the load is applied to all the hydraulic cylinders 1a, 1b or 1c, 1d, 1e, 1f. Alternatively, when the hydraulic oil supply pressure in the line connected to 3c, 3d, 3e, 3f is increased, the pressure is used as a pilot pressure, and each hydraulic cylinder 1a, 1b or 1c, 1d, 1e, 1f If there is provided a pilot operation switching valve 24 that can switch to a hydraulic circuit for supplying hydraulic oil 7 at the same flow rate to the side pressure chambers 3a, 3b or 3c, 3d, 3e, 3f, A switching valve other than the electromagnetic switching valve 8 may be used as a switching valve for switching between lift-up and lift-down. Further, the switching valve and the port and spool of the pilot operation switching valve 24 may be of a type other than shown.

  Furthermore, until the tip side of each operating rod 2a, 2b or 2c, 2d, 2e, 2f of all the hydraulic cylinders 1a, 1b or 1c, 1d, 1e, 1f comes into contact with the heavy object 5 to be moved, respectively, The hydraulic oil 7 is supplied to the cap-side pressure chambers 3a, 3b or 3c, 3d, 3e, 3f of each hydraulic cylinder 1a, 1b or 1c, 1d, 1e, 1f at the same pressure, and all the hydraulic cylinders 1a, 1b or After 1c, 1d, 1e, and 1f are in contact with the weight 5, the cap-side pressure chambers 3a, 3b or 3c, 3d, 3e, and 3f of the hydraulic cylinders 1a and 1b or 1c, 1d, 1e, and 1f are used. As long as it can be switched to a hydraulic circuit that can supply hydraulic oil 7 at the same flow rate, a hydraulic circuit configuration other than that shown in the figure may be used.

  The heavy object 5 to be moved may be a heavy object 5 in which a difference in height position does not occur between the support portions by the hydraulic cylinders 1a, 1b or 1c, 1d, 1e, 1f.

  The present invention may be applied to the case where the number of hydraulic cylinders used for moving the heavy object 5 to be moved is three or five or more.

  Furthermore, the present invention may be applied in order to synchronize the plurality of hydraulic cylinders when the heavy object 5 to be moved is moved in the lateral direction by extending the plurality of hydraulic cylinders.

  Of course, various modifications can be made without departing from the scope of the present invention.

1a, 1b, 1c, 1d, 1e, 1f Hydraulic cylinder 3a, 3b, 3c, 3d, 3e, 3f Cap side pressure chamber 5 Heavy load 7 Hydraulic oil 11 Cap side oil supply line 11a, 11b, 11c, 11d, 11e Branch Cap side oil supply line (line)
24 Pilot operated switching valve

Claims (4)

  The hydraulic oil is supplied to the cap side pressure chambers of a plurality of hydraulic cylinders for moving heavy objects at the same pressure to start the extension operation, and then the operating rods of all the hydraulic cylinders contact the heavy objects to When a load is applied to all the hydraulic cylinders, the same amount of hydraulic oil is supplied to the cap-side pressure chambers of all the hydraulic cylinders so that the hydraulic cylinders are synchronized to extend and move the heavy objects. A method for synchronizing a plurality of hydraulic cylinders.   The hydraulic oil is supplied at the same pressure to the cap side pressure chambers of a plurality of hydraulic cylinders for moving heavy objects through a circuit capable of supplying the hydraulic oil at the same pressure, and then the extension operation is started. The pressure of the hydraulic oil in the lines connected to the cap-side pressure chambers of the hydraulic cylinders when the operating rods of all the hydraulic cylinders contact the heavy objects and a load acts on the hydraulic cylinders. Is connected to a circuit that can supply the same flow rate of hydraulic oil to the cap-side pressure chamber of each hydraulic cylinder by switching the pilot operation switching valve that uses the increased pressure as the pilot pressure. Then, with the same amount of hydraulic oil supplied to the cap-side pressure chambers of all the hydraulic cylinders, the hydraulic cylinders are extended and operated in synchronization to move the heavy load. Synchronization method for multiple hydraulic cylinders, characterized by the so that.   When a plurality of hydraulic cylinders for moving heavy objects are set to be upwardly directed hydraulic cylinders, when the operating rods of all the hydraulic cylinders contact the lower surface of the heavy objects and a load is applied to all the hydraulic cylinders, 3. The multiple hydraulic cylinder according to claim 1, wherein the hydraulic fluid supplied to the cap-side pressure chamber of the hydraulic cylinder has the same flow rate so that the hydraulic cylinders are extended in synchronization to lift up the heavy load. 4. Synchronization method.   A circuit that allows hydraulic oil to be supplied to the cap-side pressure chambers of a plurality of hydraulic cylinders for moving heavy objects at the same pressure, and the operating rods of all the hydraulic cylinders come into contact with the heavy objects and all the hydraulic cylinders A pilot operation switching valve capable of switching the pressure of the hydraulic oil rising in a line connected to the cap side pressure chamber of each hydraulic cylinder when the load is applied to the pilot cylinder as a pilot pressure, and switching operation of the pilot operation switching valve A synchronizer for a plurality of hydraulic cylinders, comprising a circuit configured to supply hydraulic oil at the same flow rate to the cap-side pressure chamber of each hydraulic cylinder.

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