JP2011012458A - Hydraulic device for crusher - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve work efficiency by accelerating opening and closing of a crushing arm, and to reduce power loss upon supplying and discharging oil to a hydraulic cylinder, in a crusher provided with the crushing arm and the hydraulic cylinder opening and closing the crushing arm.SOLUTION: Piston rods 34 of opening/closing cylinders 20A, 20B are made hollow, and accumulators 35 are housed in hollow parts 34a of the piston rods 34, respectively. During the opening operation of the crushing arms 19A, 19B, the oil discharged from head-side oil chambers 20AH, 20BH is accumulated in the accumulators 35, and during the closing operation in a low-load state having no contact with an object to be crushed, the pressure oil accumulated in the accumulator 35 is supplied to the head-side oil chambers 20AH, 20BH.

Description

  The present invention belongs to the technical field of a hydraulic device for a crusher that is mounted as an attachment for crushing work on a main body of a work machine such as a dismantling work machine.

Generally, as an attachment for crushing work that is mounted on a machine body of a work machine such as a dismantling work machine, an openable / closable crushing arm that crushes symmetrical crushing objects such as iron and concrete, and a hydraulic cylinder that opens and closes the crushing arm. A crusher equipped is known. Such a crusher is generally attached to the tip of a long work arm supported by the machine body so that crushing work at a high place can be easily performed, while the hydraulic pressure of a hydraulic cylinder is The source hydraulic pump and oil tank are mounted on the body. For this reason, the hydraulic piping to the crusher is a long one that extends from the hydraulic pump or oil tank on the machine body side to the crusher via the long work arm. There is a problem that power loss due to pressure loss is large, which not only causes deterioration of fuel consumption, but also slows the response of the crushing arm, resulting in poor workability. Especially when the crushing door is open and when the crushing arm is in contact with the object to be crushed, the crushing object is not being crushed. It is hoped that In addition, it is necessary to use a large-diameter pipe in order to reduce the pressure loss of the pipe as much as possible, and there is a problem that the layout of the pipe is difficult. Furthermore, since the crusher is an attachment that requires a large flow rate, other hydraulic actuators provided on the work machine (for example, a turning motor that turns the crusher with respect to the work arm or a hydraulic cylinder that bends the work arm) Etc.), there is also a problem that the interlocking operation becomes worse.
Therefore, conventionally, when the crushing arm is closed in a low load state where the crushing arm is not in contact with the object to be crushed, the oil discharged from the rod side oil chamber of the hydraulic cylinder is merged with the oil discharged from the hydraulic pump to the head side. A technique is known in which a speed increasing valve for supplying oil is provided (see, for example, Patent Documents 1 and 2). In this case, pressure oil is supplied from the rod-side oil chamber of the hydraulic cylinder to the head-side oil chamber without passing through the long hydraulic pipe described above, which can contribute to reduction of pressure loss and from the speed increasing valve. The amount of pressure oil supplied to the head side oil chamber is increased, and the extension speed of the hydraulic cylinder can be increased.

No. 5-40126 Japanese Patent Laid-Open No. 10-266587

  However, the speed increasing valve as in Patent Documents 1 and 2 is used when the hydraulic cylinder is extended, that is, when the oil discharged from the rod side oil chamber having a small pressure receiving area is supplied to the head side oil chamber having a large pressure receiving area. This is effective, and such a speed-up valve cannot be used when the hydraulic cylinder is reduced, that is, when the opening speed of the crushing arm is increased. In addition, when the hydraulic cylinder is reduced, the discharge flow rate from the hydraulic cylinder is larger than when the hydraulic cylinder is extended due to the difference in pressure receiving area between the rod side and the head side. There is a problem that the pressure loss of the piping in the return path increases, and the reduction speed of the hydraulic cylinder slows down due to the decrease in the discharge speed.Therefore, when the hydraulic cylinder is reduced, that is, when the crushing arm is opened, Problems such as the increase in power loss due to the pressure loss of the pipe, the deterioration of workability due to the delayed response of the crushing arm, and the use of a large-diameter pipe cannot be eliminated. Further, even during the closing operation in which the crushing arm is not in contact with the object to be crushed, further reduction in power loss and improvement in operating speed are desired, and there is a problem to be solved by the present invention.

The present invention was created in view of the above-described circumstances in order to solve these problems. The invention of claim 1 is mounted as an attachment for crushing work on an airframe body of a work machine, and is opened and closed. In a crusher provided with a free crushing arm and a hydraulic cylinder that opens and closes the crushing arm, the hydraulic cylinder includes a piston that is fitted in a cylinder tube so as to reciprocate freely, and a hollow that is provided integrally with the piston. The piston rod having the structure, the head side oil chamber and the rod side oil chamber formed on both sides of the piston, the accumulator built in the hollow portion of the piston rod, and the oil chamber of the accumulator and the head side oil chamber communicate with each other. An accumulator inflow / outflow path; and an on-off valve that opens and closes the accumulator inflow / outflow path, and supplies oil to the rod side oil chamber and head side oil. The crushing arm is opened by reducing the oil discharge from the oil, while the crushing arm is closed by extending the oil supply to the head side oil chamber and the oil discharge from the rod side oil chamber and driving the hydraulic cylinder. The circuit is provided with a control valve for supplying the hydraulic pump discharge oil to the rod side oil chamber when the crushing arm is opened and to the head side oil chamber when the crushing arm is closed, while the hydraulic cylinder opening and closing valve is When the crushing arm is opened, the accumulator inflow / outflow path is opened to accumulate the oil discharged from the head side oil chamber in the accumulator, and when the crushing arm is closed in a low load state where the crushing arm is not in contact with the crushing object, The accumulator inlet / outlet passage is opened to supply the pressure oil accumulated in the accumulator to the head side oil chamber when the crushing arm is opened. A crusher configured to close the accumulator inflow / outflow path so as to shut off between the head side oil chamber and the accumulator oil chamber during a closing operation in a high load state after contacting the object to be crushed. It is a hydraulic device.
According to a second aspect of the present invention, in the hydraulic cylinder drive circuit according to the first aspect, the oil discharged from the rod side oil chamber is supplied to the head side during a closing operation in a low load state where the crushing arm is not in contact with the object to be crushed. A speed increasing circuit is provided to supply the oil discharged from the rod side oil chamber to the oil tank during closing operation under high load after the crushing arm contacts the object to be crushed while supplying to the oil chamber It is the hydraulic device of the crusher.
According to a third aspect of the present invention, in the second aspect, the on-off valve is a pilot switching valve into which the pressure in the rod side oil chamber of the hydraulic cylinder is input as a pilot pressure, and the pressure in the rod side oil chamber is preset. A crusher configured to open the accumulator inflow / outflow passage when the pressure is higher than the rod side set pressure, and to close the accumulator inflow / outflow passage when the pressure in the rod side oil chamber is lower than the rod side set pressure. It is a hydraulic device.
According to a fourth aspect of the present invention, in the third aspect of the present invention, when the speed increasing circuit is closed in a low load state where the crushing arm is not in contact with the object to be crushed, A crusher hydraulic apparatus comprising a throttle valve for restricting a flow rate of supply from a rod-side oil chamber to a head-side oil chamber so as to maintain a pressure higher than a set pressure.
According to a fifth aspect of the present invention, in the first or second aspect, the on-off valve is a pilot switching valve into which the pressure in the head side oil chamber of the hydraulic cylinder is input as a pilot pressure, and the pressure in the head side oil chamber is preset. The accumulator inflow / outflow path is opened when the pressure is lower than the set pressure on the head side, while the accumulator inflow / outflow path is closed when the pressure in the head side oil chamber is higher than the set pressure on the head side. It is a hydraulic device of a crusher.

By making it the invention of claim 1, it is possible to increase the operating speed of the crushing arm both in the opening operation of the crushing arm and in the closing operation in a low load state where the crushing object is not in contact. And can greatly contribute to the improvement of work efficiency. Moreover, when the crushing arm is opened, the flow rate of the return from the head side oil chamber to the oil tank can be reduced, while when the crushing arm is closed when the crushing arm is not in contact with the object to be crushed, The supply flow rate to the head side oil chamber can be reduced, and the power loss due to the pressure loss of the piping that serves as the oil supply / discharge path to the head side oil chamber can be greatly reduced, improving fuel efficiency. Can contribute greatly. Furthermore, the operability of interlocking between the hydraulic cylinder and another hydraulic actuator provided on the work machine is improved, and it is not necessary to make the diameter of the pipe particularly large, thereby improving the layout.
According to the invention of claim 2, at the time of closing operation in a low load state where the crushing arm is not in contact with the object to be crushed, the return flow rate from the rod side oil chamber to the oil tank can be eliminated, and the head side The oil chamber is supplied with the oil discharged from the rod side oil chamber in addition to the pressure oil supplied from the accumulator, and the supply flow rate from the hydraulic pump to the head side oil chamber can be further reduced. It can contribute to further reduction of power loss and improvement of interlocking operability. On the other hand, at the time of closing operation in a high load state after coming into contact with the object to be crushed, the pressure in the rod-side oil chamber is reduced, and high thrust for extending the hydraulic cylinder can be obtained.
According to the invention of claim 3, the on-off valve opens the accumulator inflow / outflow passage when the crushing arm is opened and when the crushing arm is closed when the crushing arm is not in contact with the crushing object. The accumulator inflow / outflow path can be closed during the closing operation in a high load state after contact.
According to the invention of claim 4, the pressure in the rod side oil chamber can be reliably maintained at the rod side set pressure or higher during the closing operation in a low load state where the crushing arm is not in contact with the object to be crushed. Thus, the operation of the on-off valve that opens the accumulator inflow / outlet passage to supply the pressure oil accumulated in the accumulator to the head-side oil chamber can be reliably performed.
According to the invention of claim 5, the on-off valve opens the accumulator inflow / outflow path when the crushing arm is opened and when the crushing arm is closed when the crushing arm is not in contact with the crushing object. The accumulator inflow / outflow path can be closed during the closing operation in a high load state after contact.

It is a general view of a demolition work machine. It is a figure which shows a crusher. It is a hydraulic circuit diagram which shows the drive circuit of the cylinder for opening and closing in 1st embodiment. It is a hydraulic circuit diagram which shows the drive circuit of the cylinder for opening and closing in 2nd embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. In FIG. 1, reference numeral 1 denotes a dismantling work machine equipped with a crusher 2 as a crushing work attachment (work of the present invention). The body body of the dismantling work machine 1 is composed of a crawler type lower traveling body 3 and an upper revolving body 4 that is pivotally supported by the lower traveling body 3. The upper revolving unit 4 is attached to and supported by a base end portion of a flexible work arm 5. In the present embodiment, the working arm 5 is supported by a boom 6 whose base end portion is supported by the upper swing body 4 so as to be swingable in the vertical direction, and by a tip portion of the boom 6 so as to be swingable in the vertical direction. The first arm 7 and the second arm 8 supported by the front end portion of the first arm 7 so as to be swingable in the vertical direction are configured, and are located on the most front end side of the working arm 5. The crusher 2 is swingably attached to the tip of the second arm 8. In the figure, reference numerals 9, 10, 11, and 12 denote a boom cylinder, a first arm cylinder, and a boom arm that extend and contract to swing the boom 6, the first arm 7, the second arm 8, and the crusher 2, respectively. The cylinder for the second arm and the cylinder for attachment.

  As shown in FIG. 2, the crusher 2 is attached to a front end portion of the work arm 5 (a front end portion of the second arm 8) so as to be swingable, and rotates to the mounting bracket 14 via a swivel bearing 15. A body 16 that can be freely attached, a turning motor 17 that rotates the body 16, a pair of crushing arms 19A and 19B that are supported by the body 16 via pin shafts 18A and 18B so as to be swingable open and close, the crushing arm 19A, A pair of open / close cylinders (corresponding to the hydraulic cylinders of the present invention) 20A and 20B that reduce and extend to open and close 19B, and a swivel joint 21 that connects hydraulic pipes so as to be rotatable relative to each other. Yes. The direction of the crushing arms 19A and 19B relative to the work arm 5 can be adjusted by driving the turning motor 17 and rotating the body 16, and the opening and closing cylinders 20A and 20B are adjusted. By crushing and extending the crushing arms 19A, 19B, the crushing objects such as iron and concrete can be crushed by the crushing arms 19A, 19B. The opening / closing cylinders 20A and 20B are swingably connected to the body 16 on the head side via pin shafts 22A and 22B, and on the rod side to the crushing arms 19A and 19B via pin shafts 23A and 23B. It is connected freely.

  Next, the drive circuit for the opening / closing cylinders 20A and 20B will be described based on the hydraulic circuit diagram of FIG. In FIG. 3, A is a circuit of a portion mounted on the machine body (upper swing body 3). The circuit A includes a hydraulic pump 25 driven by the engine E, an oil tank 26, and a crushing arm operation tool. A crushing arm control valve (corresponding to the control valve of the present invention) 27 for performing oil supply / discharge control of the opening / closing cylinders 20A and 20B based on an operation of a cylinder (not shown) is provided.

  On the other hand, B is a circuit of a part installed in the crusher 2, and the circuit B is provided with the opening and closing cylinders 20A and 20B, a swivel joint 21, a speed increasing circuit 30 described later, and the like. The open / close cylinders 20A and 20B are contracted by supplying oil to the rod side oil chambers 20AR and 20BR and discharging oil from the head side oil chambers 20AH and 20BH to open the crushing arms 19A and 19B. The crushing arms 19A and 19B are extended by the oil supply to the oil chambers 20AH and 20BH and the oil discharge from the rod side oil chambers 20AR and 20BR, and the crushing arms 19A and 19B are closed. The structure will be described later.

  Here, the crushing arm control valve 27 is a three-position switching valve that switches based on the operation of the crushing arm operation tool, and is connected to the pump port 27P connected to the hydraulic pump 25 and the oil tank 26. A tank port 27T, and a rod side port 27R and a head side port 27H respectively connected to a rod side oil passage 28 and a head side oil passage 29 described later. The crushing arm control valve 27 closes the ports 27P, 27T, 27R, and 27H when the crushing arm operation tool is not operated, and supplies and discharges oil to and from the opening and closing cylinders 20A and 20B. Although it is located in the neutral position N that is not performed, the discharge oil of the hydraulic pump 25 is supplied to the rod-side oil passage 28 based on the operation of the crushing arm operation tool to the open side, while the head-side oil passage 29 is switched to the reduction side position X for discharging the oil to the oil tank 26, and the discharge oil of the hydraulic pump 25 is transferred to the head side oil passage 29 based on the operation of the crushing arm operating tool to the closing side. On the other hand, it is configured to switch to the extension side position Y where the oil in the rod side oil passage 28 is discharged to the oil tank 26.

  The rod-side oil passage 28 is an oil passage connecting the crushing arm control valve 27 and the rod-side oil chambers 20AR, 20BR of the opening / closing cylinders 20A, 20B, and via the rod-side oil passage 28, Oil supply from the hydraulic pump 25 to the rod side oil chambers 20AR, 20BR and oil discharge from the rod side oil chambers 20AR, 20BR to the oil tank 26 are performed. The head-side oil passage 29 is an oil passage connecting the crushing arm control valve 27 and the head-side oil chambers 20AH and 20BH of the opening and closing cylinders 20A and 20B. The oil supply from the hydraulic pump 25 to the head side oil chambers 20AH and 20BH and the oil discharge from the head side oil chambers 20AH and 20BH to the oil tank 26 are performed. The pipes forming the rod side oil passage 28 and the head side oil passage 29 are not shown, but the crusher 2 is opened and closed via the work arm 5 from the crush arm control valve 27 mounted on the machine body side. It is arranged so as to reach the cylinders 20A, 20B.

  Next, the structure of the open / close cylinders 20A and 20B will be described. Since the pair of open / close cylinders 20A and 20B have the same structure, the description will be given by taking one open / close cylinder 20A as an example. Reference numeral 31 denotes a cylinder tube of the opening / closing cylinder 20A. The cylinder tube 31 is covered with a head cover 32H at one end side and covered with a rod cover 32R at the other end side. 33 is fitted in such a manner that it can reciprocate. One end of a piston rod 34 is integrally fixed to the piston 33. The other end of the piston rod 34 protrudes from the rod cover 32R so as to be movable forward and backward, and the piston protruding from the rod cover 32R. A crushing arm 19A is connected to the tip of the rod 34 via the pin shaft 23A. A head side oil chamber 20AH is formed between the piston 33 and the head cover 32H, while a rod side oil chamber 20AR is formed between the piston 33 and the rod cover 32R.

  Further, the piston rod 34 has a hollow structure, and an accumulator 35 is built in the hollow portion 34a of the piston rod 34. The accumulator 35 is a piston 35a fitted in the hollow portion 34a of the piston rod 34 so as to reciprocate (hereinafter referred to as an accumulator piston 35a in order to distinguish from the piston 33 of the opening / closing cylinders 20A, 20B). The oil chamber 35b is formed on one side of the accumulator piston 35a and a spring 35c is provided on the other side of the accumulator piston 35a. The oil chamber 35b of the accumulator 35 and the head side oil The chamber 20AH communicates with the accumulator inflow / outflow passage 36 formed through the piston 33.

  Further, the piston 33 incorporates an open / close valve 37 for opening and closing the accumulator inflow / outflow passage 36. The on-off valve 37 is a pilot switching valve having a pilot port 37a into which the pressure in the rod side oil chamber 20AR is input as a pilot pressure, and the rod side set pressure PRs in which the pressure in the rod side oil chamber 20AR is preset. The accumulator inflow / outflow path 36 is closed when the pressure is less than the value, but the accumulator inflow / outflow path 36 is opened when the pressure in the rod side oil chamber 20AR becomes equal to or higher than the rod side set pressure PRs. Then, the accumulator inflow / outflow path 36 is closed by the on-off valve 37 to block between the oil chamber 35b of the accumulator 35 and the head side oil chamber 20AH, while the accumulator inflow / outflow path 36 is opened to open the head side oil chamber. The oil discharged from 20AH is accumulated in the oil chamber 35b of the accumulator 35, or the pressure oil accumulated in the oil chamber 35b of the accumulator 35 can be supplied to the head side oil chamber 20AH.

  Here, the rod-side oil pressure chambers 20AR and 20BR when the rod-side set pressure PRs and the crushing arms 19A and 19B are opened (when the oil discharged from the hydraulic pump 25 is supplied to the rod-side oil chambers 20AR and 20BR). Pressure PR1 and the closing operation in a low load state in which the crushing arms 19A and 19B are not in contact with the crushing object (as will be described later, the exhaust oil from the rod side oil chambers 20AR and 20BR is During the closing operation in a high load state after the pressure PR2 of the rod-side oil chambers 20AR and 20BR (when supplied to the head-side oil chambers 20AH and 20BH) and the crushing arms 19A and 19B contact the crushing object (As will be described later, when the oil discharged from the rod side oil chambers 20AR and 20BR flows into the oil tank 26), the rod side oil chambers 20AR and 20B The pressures in the rod side oil chambers 20AR and 20BR are as follows: the pressure PR1 during the opening operation, the pressure PR2 during the closing operation in the low load state, and the pressure during the closing operation in the high load state. In addition to the lower pressure in the order of PR3, the rod side set pressure PRs is lower than the pressure PR1 at the time of opening and the pressure PR2 at the time of closing in the low load state, and the pressure at the time of closing in the high load state. A pressure higher than PR3 is set (PR1> PR2> PRs> PR3). Thus, when the crushing arms 19A and 19B are opened and when the open / close valve 37 is closed in a low load state where the crushing arms 19A and 19B are not in contact with the crushing object, the pressure in the rod side oil chambers 20AR and 20BR is reduced to the rod side. Since the accumulator inflow / outflow path 36 is opened because the pressure is higher than the set pressure PRs, the pressure in the rod side oil chambers 20AR and 20BR is higher than the rod side set pressure PRs during the closing operation in a high load state after contacting the object to be crushed. Therefore, the accumulator inflow / outflow path 36 is configured to be closed.

  On the other hand, the speed increasing circuit 30 discharges oil from the rod-side oil chambers 20AR and 20BR of the opening and closing cylinders 20A and 20B when the crushing arms 19A and 19B are closed in a low load state where the crushing arms 19A and 19B are not in contact with the object to be crushed. Is a circuit for supplying the oil to the head side oil chambers 20AH and 20BH, and is a communication oil that communicates the counter balance valve 38 disposed in the rod side oil passage 28 with the rod side oil passage 28 and the head side oil passage 29. The passage 39 and a pilot check valve 40 arranged in the communication oil passage 39 are used.

  The counter balance valve 38 is formed by using a pressure control valve 41 and a check valve 42. The check valve 42 is connected to the rod side oil chamber 20AR of the opening / closing cylinders 20A and 20B from the crushing arm control valve 27. , 20BR is allowed to flow, but reverse flow is blocked.

  The pressure control valve 41 has an inlet side connected to the rod side oil chambers 20AR and 20BR of the open / close cylinders 20A and 20B, an outlet side connected to the crushing arm control valve 27, and the pressure of the head side oil passage 29. Is input to the pilot port 41a. The pressure control valve 41 communicates from the rod side oil chambers 20AR and 20BR to the crushing arm control valve 27 when the pressure in the head side oil passage 29 is lower than the preset head side set pressure PHs. Although the valve path 41b is closed, the valve path 41b is opened when the pressure in the head-side oil path 29 becomes equal to or higher than the head-side set pressure PHs. When the arms 19A and 19B are closed, a minimum pressure is set when the crushing arms 19A and 19B come into contact with a crushing object to be in a high load state. Thus, when the crushing arms 19A and 19B are closed, in a low load state where the crushing arms 19A and 19B are not in contact with each other, the pressure of the head-side oil passage 29 is lower than the head-side set pressure PHs. The valve path 41b of 41 is closed, so that the flow of oil from the rod-side oil chambers 20AR, 20BR of the opening / closing cylinders 20A, 20B to the crushing arm control valve 27 is prevented while In a high load state after contact, the pressure of the head-side oil passage 29 becomes equal to or higher than the head-side set pressure PHs, so that the valve passage 41b of the pressure control valve 41 is opened, whereby the crushing arm is opened from the rod-side oil chambers 20AR, 20BR. The oil flow to the control valve 27 is allowed.

  Further, as described above, the pilot check valve 40 is disposed in the communication oil passage 39 that communicates the rod side oil passage 28 and the head side oil passage 29. The pilot check valve 40 has an inlet side on the rod side. The pilot passage 40a is connected to the oil passage 28, the outlet side is connected to the head-side oil passage 29, and a pilot port 40a to which the pilot pressure for pressing the poppet of the pilot check valve 40 toward the closing side is input. The supply pressure from the hydraulic pump 25 to the rod-side oil passage 28 is input to the pilot port 40a as a pilot pressure. Thus, when the discharge oil of the hydraulic pump 25 is not supplied from the crushing arm control valve 27 to the rod-side oil passage 28, the pilot pressure is not input to the pilot port 40a of the pilot check valve 40. The pilot check valve 40 is in a check state that allows oil flow from the rod side oil passage 28 to the head side oil passage 29 but prevents reverse flow. On the other hand, when the oil discharged from the hydraulic pump 25 is supplied from the crushing arm control valve 27 to the rod-side oil passage 28, the supply pressure is input as a pilot pressure to the pilot port 40a. Is configured to be in a closed state that prevents bidirectional flow between the rod-side oil passage 28 and the head-side oil passage 29.

  Thus, when the crushing arms 19A and 19B are closed, in a low load state where the crushing arms 19A and 19B are not in contact with the crushing object, the pressure control valve 41 of the counter balance valve 38 causes the rod side oil chambers of the opening and closing cylinders 20A and 20B. The flow of oil from 20AR, 20BR to the crushing arm control valve 27 is blocked, thereby preventing oil from being discharged from the rod side oil chambers 20AR, 20BR to the oil tank 26 and being disposed in the communication oil passage 39. The pilot check valve 40 is in a non-return state that allows oil to flow from the rod-side oil passage 28 to the head-side oil passage 29, whereby the rod-side oil chamber 20AR of the open / close cylinders 20A, 20B The oil discharged from 20BR is supplied to the head side oil chambers 20AH and 20BH via the communication oil passage 39. On the other hand, in a high load state after coming into contact with the object to be crushed, the pressure control valve 41 of the counter balance valve 38 allows oil to flow from the rod side oil chambers 20AR, 20BR to the crushing arm control valve 27, As a result, the oil discharged from the rod side oil chambers 20AR and 20BR flows to the oil tank 26 via the crushing arm control valve 27.

  Further, a throttle valve 43 for restricting the supply flow rate from the rod side oil chambers 20AR, 20BR of the open / close cylinders 20A, 20B to the head side oil chambers 20AH, 20BH is disposed in the communication oil passage 39. When the throttle valve 43 closes the crushing arms 19A and 19B in a low load state where the crushing arms 19A and 19B are not in contact with the crushing object, the pressure PR2 of the rod side oil chambers 20AR and 20BR is set to the rod side set pressure PRs described above. The structure is such that it can be held at a high pressure more reliably.

  Next, oil supply and discharge to the open / close cylinders 20A and 20B when the crushing arms 19A and 19B are opened and closed will be described. First, when the crushing arms 19A and 19B are opened, that is, when the crushing arm operation tool is operated to open the crushing arms 19A and 19B, the crushing arm control valve 27 is moved to the reduction side position X. Then, the oil discharged from the hydraulic pump 25 is supplied to the rod-side oil passage 28. The oil discharged from the hydraulic pump 25 supplied to the rod side oil passage 28 reaches a counter balance valve 38 constituting the speed increasing circuit 30, and the opening / closing cylinder 20 </ b> A via the check valve 42 of the counter balance valve 38. The cylinders 20A and 20B for opening and closing are contracted by being supplied to the rod side oil chambers 20AR and 20BR of 20B. At this time, since the supply pressure from the hydraulic pump 25 to the rod side oil passage 28 is input as a pilot pressure to the pilot port 40a of the pilot check valve 40 constituting the speed increasing circuit 30, the pilot check valve 40 The closed state prevents the bidirectional flow between the side oil passage 28 and the head side oil passage 29. Thereby, it is possible to prevent the pressure oil supplied from the hydraulic pump 25 to the rod side oil passage 28 from flowing into the head side oil passage 29 via the communication oil passage 39.

  Furthermore, the pressure PR1 of the rod side oil chambers 20AR and 20BR of the opening and closing cylinders 20A and 20B during the opening operation of the crushing arms 19A and 19B is higher than the rod side set pressure PRs as described above. The on-off valve 37 is connected to the oil chamber 35b of the accumulator 35 built in the piston rod 34 by inputting the pressure PR1 of the rod side oil chambers 20A, 20B higher than the rod side set pressure PRs to the pilot port 37a. The accumulator inflow / outflow passage 36 that communicates with the head side oil chambers 20AH and 20BH is opened. Thus, the oil discharged from the head side oil chambers 20AH and 20BH as the opening and closing cylinders 20A and 20B are reduced is accumulated in the oil chamber 35b of the accumulator 35 through the opening and closing valve 37. The remaining oil discharged from the head side oil chambers 20AH and 20BH flows to the oil tank 26 via the head side oil passage 29 and the crushing arm control valve 27. In this case, as described above, the pipe forming the head side oil passage 29 is long through the work arm 5 and has a large pressure loss. Therefore, the oil discharged from the head side oil chambers 20AH and 20BH is discharged. Most of the pressure is accumulated in an oil chamber 35 b of an accumulator 35 built in the piston rod 34.

  That is, when the crushing arms 19A and 19B are opened, the oil discharged from the hydraulic pump 25 is supplied to the rod-side oil chambers 20AR and 20BR of the open / close cylinders 20A and 20B, while the oil discharged from the head-side oil chambers 20AH and 20BH. Most of the pressure is accumulated in an accumulator 35 built in the piston rod 34, and the rest flows into the oil tank 26. Thus, the return flow rate from the head side oil chambers 20AH and 20BH to the oil tank 26 can be greatly reduced, power loss due to pressure loss of the piping in the return path can be reduced, and the head side oil chamber can be reduced. The discharge speed from 20AH and 20BH is increased, and the reduction speed of the opening and closing cylinders 20A and 20B, that is, the opening speed of the crushing arms 19A and 19B can be increased.

  On the other hand, when the crushing arm 19A, 19B is closed, that is, when the crushing arm control tool 27 is operated to close the crushing arm 19A, 19B, the crushing arm control valve 27 is moved to the extended position Y. Then, the oil discharged from the hydraulic pump 25 is supplied to the head side oil passage 29. The oil discharged from the hydraulic pump 25 supplied to the head side oil passage 29 is supplied to the head side oil chambers 20AH and 20BH of the opening and closing cylinders 20A and 20B, thereby extending the opening and closing cylinders 20A and 20B.

  Further, when the crushing arms 19A and 19B are closed, in a low load state where the crushing arms 19A and 19B are not in contact with the crushing object, the pressure of the head side oil passage 29 is lower than the head side set pressure PHs described above. Input to the pilot port 41 a of the valve 41. For this reason, the pressure control valve 41 closes the valve path 41b and is in a state of preventing oil discharge from the rod side oil chambers 20AR, 20BR to the oil tank 26. Further, since no pressure oil is supplied from the hydraulic pump 25 to the rod-side oil passage 28 to the pilot port 40a of the pilot check valve 40, no pilot pressure is input. Is in a check state that allows oil to flow from the oil passage 29 to the head side oil passage 29. Thus, the oil discharged from the rod side oil chambers 20AR and 20BR along with the extension of the opening and closing cylinders 20A and 20B flows into the head side oil passage 29 via the pilot check valve 40, and from the hydraulic pump 25 described above. Is supplied to the head side oil chambers 20AH and 20BH.

  Furthermore, when the crushing arms 19A and 19B are closed, the pressure PR2 of the rod-side oil chambers 20AR and 20BR in a low load state that is not in contact with the crushing object is higher than the rod-side set pressure PRs as described above. Thus, the on-off valve 37 has an accumulator 35 built in the piston rod 34 when the pressure PR2 in the rod side oil chambers 20AR, 20BR higher than the rod side set pressure PRs is input to the pilot port 37a. The accumulator inflow / outflow passage 36 that communicates the oil chamber 35b with the head side oil chambers 20AH and 20BH is opened. Thus, the pressure oil accumulated in the accumulator 35 when the crushing arms 19A and 19B are opened is supplied to the head side oil chambers 20AH and 20BH via the accumulator inflow / outflow passage 36.

  In other words, in the low load state where the crushing arms 19A and 19B are not in contact with the crushing object when the crushing arms 19A and 19B are closed, the discharge oil of the hydraulic pump 25 and the rod are provided in the head side oil chambers 20AH and 20BH of the opening and closing cylinders 20A and 20B. The oil discharged from the side oil chambers 20AR and 20BR is joined and supplied, and the pressure oil accumulated in the accumulator 35 built in the piston rod 34 is supplied. In this case, since most of the oil discharged from the head side oil chambers 20AH and 20BH is accumulated in the accumulator 35 during the opening operation of the crushing arms 19A and 19B, as described above, the accumulator 35 stores the head side oil chamber 20AH. , 20BH is supplied in a short time, and the oil discharged from the rod-side oil chambers 20AR and 20BR is joined to the oil discharged from the hydraulic pump 25 and supplied to the head-side oil chambers 20AH and 20BH. Thus, the extension speed of the opening / closing cylinders 20A and 20B, that is, the opening speed of the crushing arms 19A and 19B can be increased, and the supply flow rate from the hydraulic pump 25 to the head side oil chambers 20AH and 20BH is greatly reduced. Thus, the power loss due to the pressure loss of the piping in the pressure oil supply path can be reduced.

  On the other hand, when the crushing arms 19A and 19B are closed, the pressure in the head-side oil passage 29 becomes higher than the head-side set pressure PHs described above in a high load state after contacting the crushing object. Is input to the pilot port 41 a of the pressure control valve 41. As a result, the pressure control valve 41 opens the valve passage 41b and allows the oil to flow from the rod side oil chambers 20AR, 20BR to the crushing arm control valve 27. Thus, the oil discharged from the rod side oil chambers 20AR and 20BR along with the extension of the opening and closing cylinders 20A and 20B flows to the crushing arm control valve 27 via the pressure control valve 41, and the crushing arm control The oil is discharged from the valve 27 to the oil tank 26.

  Furthermore, when the crushing arms 19A and 19B are closed, the pressure PR3 of the rod side oil chambers 20AR and 20BR in a high load state after contacting the crushing object is lower than the rod side set pressure PRs as described above. Thus, the on-off valve 37 closes the accumulator inflow / outflow path 36 that connects the oil chamber 35b of the accumulator 35 built in the piston rod 34 and the head side oil chambers 20AH and 20BH. As a result, the oil chamber 35b of the accumulator 35 and the head side oil chambers 20AH and 20BH are shut off, and the pressure oil supplied from the hydraulic pump 25 to the head side oil chambers 20AH and 20BH is accumulated in the accumulator 35. It is designed not to end up.

  That is, in a high load state after contact with the object to be crushed when the crushing arms 19A and 19B are closed, the oil discharged from the hydraulic pump 25 is supplied to the head side oil chambers 20AH and 20BH and the rod side oil chamber 20AR. The oil discharged from 20BR is discharged to the oil tank 26 via the crushing arm control valve 27, so that a high thrust force for extending the opening / closing cylinders 20A and 20B can be obtained. It has become.

  In this embodiment configured as described, the body body of the dismantling work machine 1 has openable and closable crushing arms 19A and 19B as crushing work attachments for crushing iron, concrete, and the like, and the machine crushing arm 19A. The crushing machine 2 including the opening and closing cylinders 20A and 20B for opening and closing the 19B is mounted. The opening and closing cylinders 20A and 20B include a piston 33 fitted in the cylinder tube 31 so as to be reciprocally movable, A hollow piston rod 34 provided integrally with the piston 33, head side oil chambers 20AH, 20BH and rod side oil chambers 20AR, 20BR formed on both sides of the piston 33, and a hollow portion 34a of the piston rod 34 A built-in accumulator 35, an oil chamber 35b of the accumulator 35, and head side oil chambers 20AH and 20BH The accumulator inflow / outflow passage 36 and the open / close valve 37 for opening / closing the accumulator inflow / outflow passage 36 are provided, and the oil supply to the rod side oil chambers 20AR, 20BR and the head side oil chambers 20AH, 20BH are provided. The crushing arms 19A, 19B are opened by reducing the oil discharged from the oil, while the crushing arms 19A, 19B are extended by supplying oil to the head side oil chambers 20AH, 20BH and discharging oil from the rod side oil chambers 20AR, 20BR. 19B is closed. Further, in the drive circuit of the opening / closing cylinders 20A and 20B, the discharge oil of the hydraulic pump 25 is supplied to the rod side oil chambers 20AR and 20BR when the crushing arms 19A and 19B are opened, and the crushing arms 19A and 19B are closed. A crushing arm control valve 27 is sometimes provided to supply the head side oil chambers 20AH and 20BH, while the on-off valve 37 is discharged from the head side oil chambers 20AH and 20BH when the crushing arms 19A and 19B are opened. The accumulator inflow / outflow path 36 is opened to accumulate oil in the accumulator 35, and when the crushing arms 19A, 19B are closed in a low load state where they are not in contact with the crushing object, the crushing arms 19A, 19B are opened. In order to supply the pressure oil accumulated in the accumulator 35 to the head side oil chambers 20AH and 20BH. When the accumulator inflow / outflow path 36 is opened and the crushing arms 19A and 19B are brought into contact with the object to be crushed and closed in a high load state, the head side oil chambers 20AH and 20BH and the oil chamber 35b of the accumulator 35 The accumulator inflow / outflow path 36 is closed in order to shut off.

  Thus, when the crushing arms 19A and 19B are opened, the oil discharged from the hydraulic pump 25 is supplied to the rod-side oil chambers 20AR and 20BR of the open / close cylinders 20A and 20B, while from the head-side oil chambers 20AH and 20BH. The discharged oil is accumulated in an accumulator 35 built in the piston rod 34. Accordingly, when the crushing arms 19A and 19B are opened, the return flow rate from the head side oil chambers 20AH and 20BH to the oil tank 26 is the remaining amount accumulated in the accumulator 35, and thus the head side oil chamber 20AH. , The return flow rate from 20BH to the oil tank 26 can be greatly reduced, the power loss due to the pressure loss of the piping in the return path can be greatly reduced, and the discharge speed from the head side oil chambers 20AH and 20BH Thus, the reduction speed of the opening / closing cylinders 20A and 20B, that is, the opening speed of the crushing arms 19A and 19B can be increased.

  On the other hand, when the crushing arms 19A and 19B are closed, in a low load state where the crushing arms 19A and 19B are not in contact with the crushing object, the oil discharged from the hydraulic pump 25 is stored in the head side oil chambers 20AH and 20BH of the opening and closing cylinders 20A and 20B. While being supplied, the pressure oil accumulated in the accumulator 35 when the crushing arms 19A and 19B are opened is supplied. In this case, since the accumulator 35 is built in the piston rod 34 of the open / close cylinders 20A and 20B, a large flow rate can be supplied from the accumulator 35 to the head side oil chambers 20AH and 20BH in a short time. The extension speed of the opening / closing cylinders 20A and 20B, that is, the opening speed of the crushing arms 19A and 19B can be increased, and the supply flow rate from the hydraulic pump 25 to the head side oil chambers 20AH and 20BH can be decreased. Thus, power loss due to pressure loss of piping in the pressure oil supply path can be reduced. On the other hand, when the crushing arms 19A and 19B are closed, in a high load state after coming into contact with the crushing object, the oil discharged from the hydraulic pump 25 is supplied to the head side oil chambers 20AH and 20BH. The head-side oil chambers 20AH, 20BH and the oil chamber 35b of the accumulator 35 are shut off, and thus the pressure oil supplied from the hydraulic pump 25 to the head-side oil chambers 20AH, 20BH is accumulated in the accumulator 35. However, it will be used as pressure oil for extending the opening / closing cylinders 20A and 20B, and a crushing force necessary for crushing a crushing object such as iron or concrete can be secured.

  As a result, it is possible to increase the operating speed of the crushing arms 19A and 19B both when the crushing arms 19A and 19B are opened and when the crushing arms 19A and 19B are closed in a low load state where they are not in contact with the crushing object. And can greatly contribute to the improvement of work efficiency. In addition, when the crushing arms 19A and 19B are opened, the return flow rate from the head side oil chambers 20AH and 20BH to the oil tank 26 can be reduced, while the closed state in a low load state that is not in contact with the crushing object. At the time of operation, the supply flow rate from the hydraulic pump 25 to the head side oil chambers 20AH and 20BH can be reduced, so that the power loss due to the pressure loss of the piping forming the head side oil passage 29 is greatly increased. It can be reduced and can greatly contribute to the improvement of fuel consumption. Furthermore, the closing operation of the crushing arms 19A and 19B and other hydraulic actuators (for example, the turning motor 17, the boom cylinder 9, the first arm cylinder 10, the second arm cylinder 11, the attachment) In addition, the operability with the cylinder 12 and the like is improved, and it is not necessary to make the diameter of the pipe particularly thick, thereby improving the layout. In addition, because of the relationship between the pressure receiving areas on the head side and the rod side, the oil supply / discharge flow rate for the head side oil chambers 20AH, 20BH is larger than the oil supply / discharge flow rate for the rod side oil chambers 20AR, 20BR. Further, the return flow rate from the head side oil chambers 20AH and 20BH to the oil tank 26 and the supply flow rate from the hydraulic pump 25 to the head side oil chambers 20AH and 20BH can be reduced. It can greatly contribute to improvement and diameter reduction of piping.

  Further, in this configuration, a counter balance valve 38 disposed in the rod side oil passage 28, a communication oil passage 39 communicating the rod side oil passage 28 and the head side oil passage 29, and the communication oil passage 39 are disposed. A speed increasing circuit 30 configured using the pilot check valve 40 is provided. The speed increasing circuit 30 causes the oil discharged from the rod side oil chambers 20AR, 20BR when the crushing arms 19A, 19B are closed to be discharged in the head side oil chamber 20AH, While being supplied to 20BH, it flows to the oil tank 26 in a high load state in contact with the object to be crushed. Thus, at the time of the closing operation in a low load state that is not in contact with the object to be crushed, the return flow rate from the rod side oil chambers 20AR, 20BR to the oil tank 26 can be eliminated, and the head side oil chambers 20AH, 20BH. In addition to the supply pressure oil from the accumulator 35 described above, the oil discharged from the rod side oil chambers 20AR and 20BR is also supplied, and the supply flow rate from the hydraulic pump 25 to the head side oil chambers 20AH and 20BH is reduced. Therefore, the power loss can be further reduced, and the power loss can be further reduced and the interlocking operability can be improved. On the other hand, at the time of closing operation in a high load state after coming into contact with the object to be crushed, the pressure in the rod-side oil chambers 20AR, 20BR is reduced to obtain a high thrust for extending the opening / closing cylinders 20A, 20B. Can do.

  The on-off valve 37 for opening and closing the accumulator inflow / outlet passage 36 is a pilot switching valve to which the pressure of the rod-side oil chambers 20AR, 20BR of the on-off cylinders 20A, 20B is input as a pilot pressure, and the rod-side oil chamber 20AR. When the pressure of 20BR is equal to or higher than a preset rod side set pressure PRs, the accumulator inflow / outflow passage 36 that connects the oil chamber 35b of the accumulator 35 and the head side oil chambers 20AH and 20BH is opened, while the rod side oil When the pressure in the chambers 20AR and 20BR is less than the rod-side set pressure PRs, the accumulator inflow / outflow path 36 is closed. Thus, the rod side set pressure PRs is lower than the pressure of the rod side oil chambers 20AR and 20BR during the opening operation of the crushing arms 19A and 19B and during the closing operation in a low load state, and is in a high load state. By setting a pressure higher than the pressure at the time of closing operation in the accumulator 35, the on-off valve 37 is stored in the accumulator 35 to accumulate the discharged oil from the head side oil chambers 20AH and 20BH when the crushing arms 19A and 19B are opened. In the closing operation in a low load state where the inflow / outflow passage 36 is opened and is not in contact with the object to be crushed, the accumulator is supplied to supply the pressure oil accumulated in the accumulator 35 to the head side oil chambers 20AH and 20BH during the opening operation. At the time of closing operation in a high load state after opening the inflow / outlet passage 36 and contacting the object to be crushed, the head side oil chambers 20AH and 20BH It can be configured to close the accumulator inlet Detchi 36 in order to shut off between the oil chamber 35b of the accumulator 35. As described above, the oil discharged from the rod side oil chambers 20AR and 20BR is supplied to the head side oil chambers 20AH and 20BH by the speed increasing circuit 30 during the closing operation in the low load state. Since the oil flows in the oil tank 26 during the closing operation, the pressures of the rod side oil chambers 20AR and 20BR are higher in the closing operation in the low load state than in the closing operation in the high load state.

  Further, the pressure in the rod side oil chambers 20AR and 20BR is applied to the communication oil passage 39 constituting the speed increasing circuit 30 during the closing operation in a low load state where the crushing arms 19A and 19B are not in contact with the object to be crushed. A throttle valve 43 that restricts the supply flow rate from the rod-side oil chambers 20AR, 20BR to the head-side oil chambers 20AH, 20BH is disposed so as to be surely higher than the rod-side set pressure PRs. Thus, during the closing operation in a low load state, the pressure in the rod side oil chambers 20AR, 20BR can be reliably maintained at the rod side set pressure PRs or higher, and the pressure oil accumulated in the accumulator 35 is supplied to the head side. The operation of the on-off valve 37 that opens the accumulator inflow / outflow passage 36 to be supplied to the oil chambers 20AH and 20BH can be reliably performed.

  Of course, the present invention is not limited to the first embodiment. For example, in the first embodiment, the pressure of the rod-side oil chamber is used as an on-off valve for opening and closing the accumulator inflow / outflow passage. Although a pilot switching valve having a pilot port to which is inputted as pilot pressure is used, as in the second embodiment shown in FIG. 4, the pilot switching in which the pressure in the head side oil chamber is inputted as pilot pressure is used. An on-off valve that opens and closes the accumulator inflow / outlet path can also be configured using the valve.

  That is, the on-off valve 44 of the second embodiment is a pilot switching valve having a pilot port 44a into which the pressure of the head side oil chambers 20AH and 20BH of the hydraulic cylinders 20A and 20B is input as a pilot pressure. When the pressure in the side oil chambers 20AH and 20BH is less than the preset head side set pressure PHs, the accumulator inflow / outlet passage 36 is opened, but the pressure in the head side oil chambers 20AH and 20BH is equal to or higher than the head side set pressure PHs. In this case, the accumulator inflow / outflow path 36 is closed. The head-side set pressure PHs is set to a minimum pressure when the crushing arms 19A and 19B come into contact with the crushing object and become a high load state when the crushing arms 19A and 19B are closed (first). The same pressure as the head side set pressure PHs in the embodiment). Thus, when the crushing arms 19A and 19B are opened and when the on-off valve 44 is closed in a low load state where the crushing arms 19A and 19B are not in contact with the crushing object, the pressure of the head side oil chambers 20AH and 20BH is reduced to the head side. Since the accumulator inflow / outflow path 36 is opened because it is less than the set pressure PHs, the pressure in the head side oil chambers 20AH and 20BH becomes equal to or higher than the head side set pressure PHs in a high load state after coming into contact with the object to be crushed. The accumulator inflow / outflow path 36 is configured to be closed.

  Therefore, the on-off valve 44 of the second embodiment is similar to the on-off valve 37 of the first embodiment, and the oil discharged from the head side oil chambers 20AH, 20BH when the crushing arms 19A, 19B are opened. When the crushing arms 19A and 19B are opened, the accumulator is opened when the crushing arms 19A and 19B are closed. The accumulator inflow / outflow path 36 is opened to supply the pressure oil accumulated in the head 35 to the head side oil chambers 20AH and 20BH, and the closing operation in a high load state after the crushing arms 19A and 19B come into contact with the crushing object. Occasionally, the accumulator inflow / outflow passage 3 is used to block between the head side oil chambers 20AH and 20BH and the oil chamber 35b of the accumulator 35. It will be operated to close the, thus, also in those of the second embodiment, so that the same effects as the first embodiment described above. In the second embodiment, the pressure in the rod side oil chambers 20AR and 20BR is set to the rod side set pressure during the closing operation in a low load state where the crushing arms 19A and 19B are not in contact with the object to be crushed. Since it is not necessary to hold the pressure higher than PRs, the speed increasing circuit 30 is not provided with a throttle valve. Other than the on-off valve 44 and the throttle valve are the same as those in the first embodiment, and therefore, the same reference numerals are given and the description thereof is omitted.

  Further, the present invention is limited to a crusher having a structure in which a pair of crushing arms are opened and closed by a pair of hydraulic cylinders (opening and closing cylinders 20A and 20B) as in the first and second embodiments. There is no crusher with a structure that opens and closes a pair of crushing arms with a single hydraulic cylinder, or a crusher with a structure in which only one of the pair of crushing arms opens and closes and the other crushing arm is fixed. Can also be implemented. Of course, the present invention can be implemented even with a crusher having a structure in which the crushing arm does not rotate with respect to the working arm.

  INDUSTRIAL APPLICABILITY The present invention can be used for a hydraulic device for a hydraulic cylinder for opening and closing a crushing arm of a crusher in a crusher mounted as an attachment for crushing work on a main body of a work machine such as a dismantling work machine. .

DESCRIPTION OF SYMBOLS 1 Demolition work machine 2 Crusher 19A, 19B Crush arm 20A, 20B Open / close cylinder 20AH, 20BH Head side oil chamber 20AR, 20BR Rod side oil chamber 25 Hydraulic pump 26 Oil tank 27 Crush arm control valve 30 Speed increase circuit 31 Cylinder Tube 33 Piston 34 Piston rod 34a Hollow portion 35 Accumulator 35b Accumulator oil chamber 36 Accumulator inflow / outflow path 37 Open / close valve 38 Counter balance valve 40 Pilot check valve 43 Throttle valve 44 Open / close valve

Claims (5)

In a crusher equipped with a crushing work attachment attached to the machine body of the work machine and having a crushing arm that can be freely opened and closed, and a hydraulic cylinder that opens and closes the crushing arm,
The hydraulic cylinder is
A piston fitted in the cylinder tube so as to be reciprocally movable; a piston rod having a hollow structure provided integrally with the piston; a head side oil chamber and a rod side oil chamber formed on both sides of the piston; An accumulator built in the hollow portion; an accumulator inflow / outlet passage communicating the accumulator oil chamber and the head side oil chamber; and an open / close valve that opens and closes the accumulator inflow / outlet passage to the rod side oil chamber. The crushing arm is opened by reducing the oil supply and the oil discharge from the head side oil chamber, while the crushing arm is closed by extending the oil supply to the head side oil chamber and the oil discharge from the rod side oil chamber. As well as
The hydraulic cylinder drive circuit is provided with a control valve for supplying the oil discharged from the hydraulic pump to the rod side oil chamber when the crushing arm is opened and supplying the head side oil chamber when the crushing arm is closed,
When opening the crushing arm of the hydraulic cylinder open / close valve, the accumulator inflow / outflow path is opened to accumulate the oil discharged from the head side oil chamber in the accumulator, and the crushing arm is not in contact with the crushing object. When the crushing arm is closed, the accumulator inflow / outflow path is opened to supply the pressure oil accumulated in the accumulator to the head side oil chamber when the crushing arm is opened, and the crushing arm is in contact with the object to be crushed. A hydraulic apparatus for a crusher configured to close an accumulator inflow / outflow path so as to block between a head-side oil chamber and an accumulator oil chamber during a closing operation in a high load state.   In claim 1, when closing operation in a low load state where the crushing arm is not in contact with the object to be crushed, the oil discharged from the rod side oil chamber is supplied to the head side oil chamber. A hydraulic device for a crusher provided with a speed increasing circuit for flowing the oil discharged from the rod side oil chamber to the oil tank during the closing operation in a high load state after the crushing arm comes into contact with the object to be crushed .   3. The on-off valve according to claim 2, wherein the on-off valve is a pilot switching valve in which the pressure in the rod side oil chamber of the hydraulic cylinder is input as a pilot pressure, and the pressure in the rod side oil chamber is equal to or higher than a preset rod side set pressure. The crusher hydraulic device is configured to open the accumulator inflow / outflow passage and close the accumulator inflow / outflow passage when the pressure in the rod side oil chamber is lower than the rod side set pressure.   4. The speed increasing circuit holds the pressure in the rod-side oil chamber of the hydraulic cylinder at a pressure higher than the rod-side set pressure when the crushing arm is closed in a low load state where the crushing arm is not in contact with the object to be crushed. A crusher hydraulic device, characterized in that a throttle valve is provided for reducing the supply flow rate from the rod side oil chamber to the head side oil chamber.   3. The on-off valve according to claim 1, wherein the on-off valve is a pilot switching valve into which the pressure in the head side oil chamber of the hydraulic cylinder is input as a pilot pressure, and the pressure in the head side oil chamber is less than a preset head side set pressure. The crusher hydraulic device is configured to open the accumulator inflow / outflow path in the case of the above, and close the accumulator inflow / outflow path when the pressure in the head side oil chamber is equal to or higher than the set pressure on the head side.

Images