JP5441562B2 - Speed increase circuit - Google Patents

Description

  The present invention relates to a speed increasing circuit that speeds up the expansion or contraction of a rod in a hydraulic cylinder.

  The speed increasing circuit is, for example, a hydraulic cylinder used in a crusher that crushes a target structure by opening and closing a movable jaw (in the present invention, it is particularly referred to as an operating cylinder, and each part of the operating cylinder is referred to as “operation”). The extension of the operating rod is increased and the closing operation of the movable jaw is accelerated. For example, in the speed increasing circuit disclosed in Patent Document 1, oil that is pushed by a moving operating piston and discharged from an operating rod side section is converted into a bottom side line (originally a hydraulic line connected to the bottom side of the operating cylinder, For convenience, it is called the bottom side line.) By returning to the operating bottom side section, the extension of the operating rod is accelerated and the closing operation of the movable jaw is accelerated. When the speed increasing circuit is used, the thrust of the actuating rod during the speed reduction becomes small, but when the movable jaw comes into contact with the target structure, the oil flow is made normal and the thrust by the oil is returned to its original strength (patent) (Refer FIG. 1 and FIG. 2 of literature 1). Patent Document 1 exemplifies a speed increasing circuit applied to a single-mouthed jaw crusher, but the speed increasing circuit can also be applied to a double-ended jaw type crusher by branching a hydraulic line.

Japanese Patent Laid-Open No. 10-266587

  The speed increasing circuit disclosed in Patent Document 1 speeds up the closing operation of the movable jaw, but does not change the opening operation. In order to simplify the explanation, it is assumed that the oil supply / discharge ratio between the operating bottom side section and the operating rod side section when the operating piston is moved is 2: 1. Further, it is assumed that the oil of the flow rate “1” is supplied from the pump through the rod side line (originally, the hydraulic line connected to the rod side section of the working cylinder is called the rod side line for convenience) or the bottom side line. . When closing the movable jaw, the oil discharged from the operating rod side section is returned to the bottom side line and added to the oil supplied to the operating bottom side section. For this reason, when oil with a flow rate of “1” is supplied from the pump to the operating bottom side section through the bottom side line, the oil with a flow rate of “1” is returned from the operating rod side section to the bottom side line, and to the operating bottom side section. The oil at the flow rate “2” is supplied, and the closing operation of the movable jaw is made twice as fast as when there is no speed increasing circuit. Since all the oil discharged from the operating rod side section is returned to the operating bottom side section, pressure loss does not substantially occur.

  On the other hand, when the movable jaw is opened, the oil with the flow rate “1” is supplied from the pump to the operating rod side section as it is, so that the opening operation of the movable jaw is not accelerated. Rather, since the oil having a flow rate of “2” is discharged from the operating bottom side section, the oil supplied from the rod side line is reduced due to the pressure loss generated in the bottom side line, and the movement of the operating piston is decelerated to some extent. It can be considered that the crusher is sufficient if the closing operation of the movable jaw is fast, and the speed increasing circuit may be able to accelerate the closing operation. There is no point in making the opening operation slow. Therefore, we studied to develop a speed increasing circuit that speeds up the extension and contraction of the operating rod in the operating cylinder used in the crusher of construction machinery.

  As a result of the study, the one developed by supplying the oil to the operating bottom side section to extend the operating rod, and supplying the oil to the operating rod side section to shorten the operating rod, in the speed increasing circuit of the operating cylinder, the reverse bottom side The reversing cylinder is equipped with a reversing cylinder in which the oil supply / discharge ratio between the section and the reversing rod side section is equal to the oil supply / discharge ratio between the working bottom section and the operating rod side section. Connect the section to the working bottom side section, connect the reversing rod side section to the bottom side line, supply oil to the working bottom side section via the reversing cylinder, and extend the working rod when loaded, working bottom side It is a speed increasing circuit of the working cylinder which connects the section to the bottom line and supplies oil to the working bottom section without going through the reversing cylinder. In the present invention, as in the working cylinder, each part in the reversing cylinder is referred to as “reversing”.

A specific speed increasing circuit has a reverse cylinder and a bottom upstream switching valve interposed in a bottom line extending from a pump or a tank, and the reverse cylinder has an oil supply / discharge ratio between the reverse bottom section and the reverse rod side section. The hydraulic cylinder is equal to the oil supply / discharge ratio between the operating bottom section and the operating rod section. The reverse bottom section is connected to the operating bottom section by the bottom downstream line, and the bottom upstream switching valve is connected to the bottom upstream. Connect the pilot line to the bottom line, connect the bottom line and the bottom upstream basic line as usual, connect the bottom upstream inlet to the bottom line, and switch at the time of load, switching between the bottom line and the bottom upstream a branch line communicates with connected to the inverting rod side defining the bottom side upstream before switching outlet by bottom upstream base line, bottom on The after switching outlet constituting connected to the work moving bottom compartment.

A more preferable speed increasing circuit has a bottom-side downstream switching valve interposed in the bottom-side downstream line and a rod-side switching valve interposed in the rod-side line extending from the pump or tank, and the bottom-side downstream switching valve has a bottom-side downstream pilot line. connected to the bottom side line, a bottom-side downstream inlet connected to the inverted bottom defined by the bottom side downstream line, the bottom side downstream before switching outlet communicates with the bottom side downstream line and the bottom side downstream base line at no load connected to the work moving bottom compartment switched when the load, while communication between the bottom side downstream line and the bottom side downstream branch line connects the bottom downstream after switching outlet and rod side line, the rod-side switching valve The rod side pilot line is connected to the bottom side line, and the rod side inlet is connected to the operating rod side section by the rod side basic line. Continued, and the rod side before switching outlet communicates with the rod side base line and the rod-side line when no load is connected to the Rod side line, switched during loading, and a rod-side base line and the rod-side branch line and communicated to configured by connecting換後outlet rod side switching the inversion rod side compartment.

  If the oil supply / discharge ratio between the reverse bottom section and the reverse rod side section is equal to the oil supply / discharge ratio between the operation bottom section and the operation rod side section, the reverse cylinder, for example, the inner diameter of the reverse tube or the reverse piston The moving range may be different from the inner diameter of the working tube or the moving range of the working piston. However, since the oil supply / discharge ratio between the reverse bottom section and the reverse rod section is equal to the oil supply / discharge ratio between the operation bottom section and the operation rod section, the reverse piston moves in the same manner as the operating piston. It is preferable to do. From this point, it is preferable to use a hydraulic cylinder having the same specification as that of the working cylinder, preferably a hydraulic cylinder having exactly the same specifications regarding the movement of the reverse piston, such as at least the inner diameter of the reverse tube and the moving range of the reverse piston. The reversing cylinder does not work externally and always keeps the reversing rod unloaded.

  The speed increasing circuit of the present invention constitutes a function selection mechanism that switches between oil flow priority or thrust priority by the reverse cylinder and the bottom-side upstream switching valve. This increases the flow rate of the oil fed to the operating bottom side section when the operating rod extends, and suppresses or prevents the occurrence of pressure loss due to the oil discharged from the operating bottom side section when the operating rod contracts. In addition, both the speed reduction and the speed reduction are increased (deceleration due to pressure loss that has conventionally occurred is eliminated, and the speed is increased compared to the conventional speed). The bottom side downstream switching valve and the rod side switching valve constitute a piston synchronization mechanism that synchronizes the working piston and the reverse piston. Thereby, the working piston and the reversing piston can be moved by the same amount, and the reversing piston can first reach the start or end of the reversing tube, thereby eliminating the possibility that the reversing piston hinders the movement of the working piston.

  Hereinafter, the operation of the speed increasing circuit of the present invention including all of the reversing cylinder, the bottom side upstream switching valve, the bottom side downstream switching valve, and the rod side switching valve will be described. Here, in order to simplify the explanation as described above, it is assumed that the oil supply / discharge ratio between the operating bottom side section and the operating rod side section when the operating piston is moved is 2: 1. The reverse cylinder is a hydraulic cylinder of the same specification in which the oil supply / discharge ratio in both compartments is the same (2: 1) as that of the working cylinder. Then, it is assumed that oil having a flow rate “1” is supplied from the pump of the construction machine body through the rod side line or the bottom side line.

  When the operating rod extends when there is no load, oil with a flow rate “1” supplied from the pump is sent to the reversing rod side section through the bottom side line, the bottom side upstream switching valve, and the bottom side upstream basic line. Thereby, the oil of the flow rate “2” discharged from the reverse bottom side section is sent to the operating bottom side section through the bottom side downstream line, the bottom side downstream switching valve, and the bottom side downstream basic line. Then, the oil having a flow rate “1” discharged from the operating rod side section is returned to the tank through the rod side basic line, the rod side switching valve, and the rod side line. Thus, the speed increasing circuit of the present invention increases the flow rate of the oil that pushes the operating piston, but the oil supplied from the pump and the oil returned to the tank have the same flow rate, and the pressure loss is reduced when the operating rod is extended. Generation | occurrence | production is prevented or suppressed greatly, the movement of an action | operation piston is accelerated, ie, the expansion | extension of an action | operation rod is accelerated.

  When the operating rod is extended at the time of loading (for example, the extension of the operating rod after the movable jaw of the crusher contacts the target structure), the oil supplied from the pump increases the hydraulic pressure, and the bottom side upstream switching valve, bottom side Both the downstream switching valve and the rod side switching valve are switched. Thereby, the oil of the flow rate “1” supplied from the pump is directly fed to the operating bottom side section through the bottom side line, the bottom side upstream switching valve, and the bottom side upstream branch line. Thus, the oil directly fed to the operating bottom side section exerts its original thrust to push the operating piston and opposes the load. Oil with a flow rate of “0.5” discharged from the operating rod side section is sent to the reversing rod side section through the rod side basic line, the rod side switching valve, the rod side branch line, and the bottom side upstream basic line. Thereby, the oil of the flow rate “1” discharged from the reverse bottom side section is returned to the tank through the bottom side downstream line, the bottom side downstream switching valve, and the bottom side downstream branch line.

  In contraction of the operating rod, oil with a flow rate “1” supplied from the pump is sent to the operating rod side section through the rod side line, the rod side switching valve, and the rod side basic line. Thereby, the oil of the flow rate “2” discharged from the operating bottom side section is sent to the reverse bottom side section through the bottom side downstream basic line, the bottom side downstream switching valve, and the bottom side downstream line. Then, the oil having a flow rate “1” discharged from the reversing rod side section is returned to the tank through the bottom side upstream basic line, the bottom side upstream switching valve, and the bottom side line. Thus, although the flow rate of the oil that pushes the working piston does not change, the flow rate of the oil returned to the tank is small. Therefore, the speed increasing circuit of the present invention reduces the pressure of the working piston without causing pressure loss due to the shortening of the working rod. The movement is not decelerated, that is, the shortening of the operating rod is increased as compared with the conventional speed increasing circuit.

  According to the present invention, it is possible to provide a speed increasing circuit that speeds up both expansion and contraction of an operating rod in an operating cylinder used in a crusher of a construction machine. In particular, in the present invention, by inserting a reversing cylinder between the pump or tank and the working cylinder, the oil fed from the pump to the working cylinder is increased by the reversing cylinder, and the oil returning from the working cylinder to the tank is decreased by the reversing cylinder. Thus, the occurrence of pressure loss is suppressed or prevented by equalizing the oil fed from the pump and the oil returning to the tank regardless of the extension and contraction of the operating rod. Since the speed increasing circuit of the present invention is applied to each working cylinder, it is basically applied to a single jaw type crusher. However, if the present invention is applied to each of a pair of cylinders, the double jaw type crusher is applied. Is also applicable. Thus, the single-jaw type or double-jaw type crusher to which the present invention is applied can speed up the opening operation and the closing operation of the movable jaw to shorten the working time of the crushing operation.

In an example of the speed increasing circuit based on this invention, it is a circuit block diagram showing the case where an operating rod is extended at the time of no load. In an example of the speed increasing circuit based on this invention, it is a circuit block diagram showing the case where an operating rod is extended at the time of load. In an example of the speed increasing circuit based on this invention, it is a circuit block diagram showing the case where an operating rod is shortened.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the configuration of the speed increasing circuit of this example will be described with reference to FIG. As shown in FIG. 1, the speed increasing circuit of this example includes a bottom side line 6 and a rod side line 7 extending from a pump or a tank (both not shown) and a reversing cylinder 2 interposed between the working cylinder 1 and The bottom-side upstream switching valve 3, the bottom-side downstream switching valve 4, and the rod-side switching valve 5 are configured. The reversing cylinder 2 of this example is a hydraulic cylinder having exactly the same specifications as the working cylinder 1, that is, the oil supply / discharge ratio between the reversing bottom side section 21 and the reversing rod side section 22 is the operating bottom side section 11 and the working rod side section 12. The hydraulic cylinder is equal to the oil supply / discharge ratio. For this reason, the inner diameter of the reversing tube 25 and the moving range of the reversing piston 23 are the same as the inner diameter of the working tube 15 and the moving range of the working piston 13. However, the reversing cylinder 2 does not work outside, and the reversing rod 24 is always unloaded.

  The bottom-side upstream switching valve 3 connects the bottom-side upstream pilot line 31 to the bottom-side line 6, connects the bottom-side upstream inlet to the bottom-side line 6, and connects the outlet before the bottom-side upstream switching by the bottom-side upstream basic line 32. The bottom-side upstream switching outlet is connected to the operating bottom-side section 11 by a bottom-side upstream branch line 33 that is connected to the reversing rod-side section 22 and merges with the bottom-side downstream basic line. In this example, a bottom-side upstream check valve 331 that allows only an oil flow toward the operating bottom-side section 11 is interposed in the bottom-side upstream branch line 33. The bottom-side upstream switching valve 3 of this example normally connects the bottom-side line 6 and the bottom-side upstream basic line 32, and when the operating rod 14 is extended when there is no load, oil is supplied from the pump to the reversing rod-side section 22. When the operating rod 14 is shortened, the oil is returned from the reverse rod side section 22 to the tank. Further, the bottom-side upstream switching valve 3 of this example is switched when the hydraulic pressure of the bottom-side line 6 becomes high, and the bottom-side line 6 and the bottom-side upstream branch line 33 are communicated to extend the operating rod 14 when loaded. In this case, oil is sent from the pump to the operating bottom side section 11.

  The bottom-side downstream switching valve 4 connects the bottom-side downstream pilot line 41 to the bottom-side line 6, connects the bottom-side downstream inlet to the inverted bottom-side section 21 by the bottom-side downstream line 44, and sets the outlet before the bottom-side downstream switching. The bottom side downstream basic line 42 is connected to the operating bottom side section 11, and the bottom side downstream switching outlet is connected to the rod side line 7 via the bottom side downstream branch line 43. The bottom-side downstream switching valve 4 of this example normally connects the bottom-side downstream line 44 and the bottom-side downstream basic line 42, and when the operating rod 14 is extended when there is no load, the bottom-side downstream section 21 is operated from the reverse bottom-side section 21. When oil is sent to the compartment 11 and the operating rod 14 is shortened, the oil is sent from the operating bottom side compartment 11 to the inverted bottom side compartment 21. Further, the bottom-side downstream switching valve 4 in this example is switched when the hydraulic pressure of the bottom-side line 6 becomes high, and the bottom-side downstream line 44 and the bottom-side downstream branch line 43 are communicated to extend the operating rod 14 when loaded. In this case, the oil can be returned from the inverted bottom side section 21 to the tank.

  The rod side switching valve 5 connects the rod side pilot line 51 to the bottom side line 6, connects the rod side inlet to the operating rod side section 12 by the rod side basic line 52, and connects the rod side switching outlet before the rod side line 7. The rod-side branch outlet 53 is connected to the reversing rod-side section 22 by a rod-side branch line 53 that joins the bottom-side upstream basic line 32. In this example, a rod side check valve 531 that allows only the flow of oil toward the reversing rod side section 22 is interposed in the rod side branch line 53. The rod side switching valve 5 of this example normally connects the rod side basic line 52 and the rod side line 7 and returns the oil from the operating rod side section 12 to the tank when the operating rod 14 is extended when there is no load. When the operating rod 14 is contracted, oil is sent from the pump to the operating rod side section 12. Further, the rod side switching valve 5 of this example is switched when the hydraulic pressure of the bottom side line 6 becomes high, the rod side basic line 52 and the rod side branch line 53 are communicated, and the operating rod 14 is extended when loaded. Oil is sent from the operating rod side section 12 to the reversing rod side section 22.

  Next, the operation of the speed increasing circuit of the present example will be described according to the extension of the operating rod 14 and the contraction of the operating rod 14 when there is no load and when the load is applied. In order to simplify the explanation, it is assumed that the oil supply / discharge ratio of the operation bottom side section 11 and the operation rod side section 12 when the operation piston 13 is moved is 2: 1. From this, the reversing cylinder 2 of this example has exactly the same specifications as the working cylinder 1, and therefore the oil supply / discharge ratio between the reversing bottom side section 21 and the reversing rod side section 22 is also 2: 1. Each of the rod side line 7 and the bottom side line 6 is connected to a pump or a tank via a switching valve (not shown) so that when one is connected to the pump, the other is connected to the tank. Then, it is assumed that the rod-side line 7 or the bottom-side line 6 connected to the pump supplies oil with a flow rate “1”. Moreover, in each figure, the oil supplied toward the working cylinder 1 is represented by a black arrow, and the oil discharged from the working cylinder 1 is represented by a white arrow.

  In the extension of the operating rod 14 at no load, as shown in FIG. 1, the bottom-side upstream switching valve 3 connects the bottom-side line 6 and the bottom-side upstream basic line 32, and the bottom-side downstream switching valve 4 is the bottom The side downstream line 44 and the bottom side downstream basic line 42 are communicated, and the rod side switching valve 5 communicates the rod side basic line 52 and the rod side line 7. Thereby, the oil with the flow rate “1” supplied from the pump is sent to the reversing rod side section 22 and pushes the reversing piston 23 to shorten the reversing rod 24. Then, by the movement of the reversing piston 23, the oil having the flow rate “2” is discharged from the reversing bottom side section 21 and sent to the working bottom side section 11, and the working piston 13 is pushed to extend the working rod 14. At this time, only oil with a flow rate “1” is supplied from the pump, but the oil fed into the operating bottom side section 11 has a flow rate “2”, and the operating piston 13 is accelerated. This is a state in which the oil supply / discharge ratio is “reversed” in the reversing cylinder 2 (the “reversing” cylinder is named in this sense).

  The movement of the working piston 13 causes the oil of the flow rate “1” to be discharged from the working rod side section 12 and returned to the tank. As will be understood from this, according to the speed increasing circuit of the present invention, the flow rate of the oil pushing the working piston 13 increases, but the oil supplied from the pump and the oil returned to the tank have the same flow rate, Prevent or greatly suppress the occurrence of pressure loss. Here, since the working cylinder 1 and the reversing cylinder 2 of this example have completely the same specifications, the moving amount of the working piston 13 and the moving amount of the reversing piston 23 are exactly the same, and both are synchronized. As a result, the reversing piston 23 reaches the movement start end or movement end before the working piston 13, and the supply or discharge of oil necessary for moving the working piston 13 is not hindered. As will be described later, the reason why the oil discharged from the working rod side section 12 is intentionally returned to the reversing rod side section 22 by the extension of the working rod 14 at the time of loading is to synchronize the working piston 13 and the reversing piston 23. Because.

As shown in FIG. 2, in the extension of the operating rod 14 under load, as a result of the hydraulic pressure in the bottom side line 6 increasing, the bottom side upstream switching valve 3 is switched and the bottom side line 6 and the bottom side upstream branch line 33 are switched. , The bottom side downstream switching valve 4 is switched to connect the bottom side downstream line 44 and the bottom side downstream branch line 43, and the rod side switching valve 5 is switched to switch the rod side basic line 52 to the rod side. The branch line 53 is connected.
As a result, the oil having the flow rate “1” supplied from the pump is directly fed into the operation bottom side section 11 and pushes the operation piston 13 to extend the operation rod 14. The speed increasing circuit of the present invention reduces the thrust because the oil of the flow rate “2” is sent to the operating bottom side section 11 through the reversing cylinder 2, but the original speed is increased by sending the oil of the flow rate “1” to the operating bottom side section 11. Unleash the thrust. From this, it can be seen that the combination of the reversing cylinder 2 and the bottom side upstream switching valve 3 constitutes a function selection mechanism for switching the flow rate priority or thrust priority of the oil supplied through the bottom line 6.

  The oil discharged from the working rod side section 12 by the movement of the working piston 13 may be returned to the tank as it is. However, as described above, in order to keep the working piston 13 and the reversing piston 23 synchronized, the oil having a flow rate of “0.5” discharged from the working rod side section 12 is sent to the reversing rod side section 22, and the reversing piston 23 is The oil is moved by the same amount as the operating piston 13 so that the oil having a flow rate “1” discharged from the reverse bottom side section 21 is returned to the tank. As a result, the operating piston 14 and the reversing piston 24 can be synchronized when the operating rod 14 is extended regardless of whether there is no load or no load. From this, it can be seen that the combination of the bottom-side downstream switching valve 4 and the rod-side switching valve 5 constitutes a piston synchronization mechanism that synchronizes the working piston 14 and the reverse piston 24. The oil returned to the tank through the reversing cylinder 2 in this way has the same flow rate as the oil supplied from the pump, and prevents or greatly suppresses the occurrence of pressure loss when the operating rod 14 is extended.

  In the contraction of the actuating rod 14, as shown in FIG. 3, the bottom-side upstream switching valve 3 communicates the bottom-side line 6 and the bottom-side upstream basic line 32, and the bottom-side downstream switching valve 4 is connected to the bottom-side downstream line 44. And the bottom-side downstream basic line 42 communicate with each other, and the rod-side switching valve 5 allows the rod-side basic line 52 and the rod-side line 7 to communicate with each other. Thereby, the oil of the flow rate “1” supplied from the pump is sent to the operating rod side section 12 and pushes the operating piston 13 to shorten the operating rod 14. Then, the movement of the working piston 13 causes the oil of the flow rate “2” to be discharged from the working bottom side section 11 and sent to the reversing bottom side section 21 to push the reversing piston 23 to extend the reversing rod 24. The oil sent to the reversing bottom side section 21 increases the flow rate, so that the reversing piston 23 is accelerated, but the reversing rod 24 does not do any work to the outside, so the oil only moves the reversing piston 23. Not too much.

  The movement of the reversing piston 23 causes the oil of the flow rate “1” to be discharged from the reversing rod side section 22 and returned to the tank. Thus, the oil returned to the tank through the reversing cylinder 2 has the same flow rate as the oil supplied from the pump, and prevents or greatly suppresses the occurrence of pressure loss. The action of preventing or greatly suppressing the occurrence of the pressure loss is due to the reversing cylinder 2 which reduces the flow rate of oil discharged from the working cylinder 1 (halved in this example) and returns it to the tank. It can also be seen that the reversing cylinder 2 constitutes a pressure loss prevention mechanism. Further, since the flow rate of the oil supplied to the operating rod side section 12 is not increased, it does not absolutely increase the contraction of the operating rod 14, but no pressure loss occurs as described above. The movement of the working piston 13 is not decelerated, and the contraction of the working rod 14 can be increased as compared with the conventional speed increasing circuit.

DESCRIPTION OF SYMBOLS 1 Acting cylinder 2 Reverse cylinder 3 Bottom side upstream switching valve 4 Bottom side downstream switching valve 5 Rod side switching valve 6 Bottom side line 7 Rod side line

Claims (3)

In the speed increasing circuit of the working cylinder that supplies oil to the working bottom side section to extend the working rod, and supplies oil to the working rod side section to shorten the working rod,
An oil supply / discharge ratio between the reverse bottom side section and the reverse rod side section is equal to the oil supply / discharge ratio between the operation bottom side section and the operating rod side section;
When extending the operating rod when there is no load, connect the reversing bottom side section to the operating bottom side section, connect the reversing rod side section to the bottom side line, and supply oil to the working bottom side section via the reversing cylinder. ,
A speed increasing circuit for an operating cylinder, wherein when the operating rod is extended during a load, the operating bottom side section is connected to the bottom side line, and oil is supplied to the operating bottom side section without going through the reversing cylinder. Interpose the reverse cylinder and the bottom upstream switching valve in the bottom line,
The reversing cylinder connects the reversing bottom side section to the operating bottom side section by the bottom side downstream line,
The bottom-side upstream switching valve connects the bottom-side upstream pilot line to the bottom-side line, connects the bottom-side upstream inlet to the bottom-side line, and normally connects the bottom-side line and the bottom-side upstream basic line to the bottom-side. the upstream before switching outlet connected to the inverting rod side compartment connected switches under load, the bottom side upstream after switching outlet communicates with the bottom-side line and the bottom side upstream branch line and the work dynamic bottom compartment claim The speed increasing circuit of the working cylinder according to 1. The bottom-side downstream switching valve is interposed in the bottom-side downstream line, and the rod-side switching valve is interposed in the rod-side line,
The bottom-side downstream switching valve connects the bottom-side downstream pilot line to the bottom-side line, and connects the bottom-side downstream inlet to the inverted bottom-side section through the bottom-side downstream line. a line communicated to connect the bottom downstream before switching outlet and work dynamic bottom compartment switched during loading, the bottom side downstream after switching outlet communicates with the bottom side downstream line and the bottom side downstream branch line b Connected to the cable side line,
The rod side switching valve has the rod side pilot line connected to the bottom side line, the rod side inlet connected to the operating rod side section by the rod side basic line, and the rod side basic line and rod side line communicate with each other when there is no load. connect the before and outlet rod side over to rod side line Te, switched during loading, claims by communicating the rod-side base line and the rod-side branch line connecting the rod side after switching outlet and inversion rod side compartment Item 3. The speed increasing circuit of the working cylinder according to item 2.

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