JP2007309359A - Working machine hydraulic circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the temperature rise of oil in a working machine with a working attachment by interchanging the oil in oil supply lines joining a pump and a tank on the base machine side to an hydraulic actuator for the working attachment. <P>SOLUTION: To both side oil supply lines 16, 17 joining the main pump 15 and the tank T to an opening/closing cylinder 14 at the tip of the attachment, a return line 24 connected to the tank T is connected via check valves 30, 31. The return line 24 has a switch operated return valve 28. By operating a control valve 18 in a state of opening the return valve 28 after interrupting work, the oil on one of high-pressure-side oil supply lines 16, 17 is returned to the tank T via the return line 24 and circulated to prevent the temperature rise of the oil. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic circuit of a work machine having a work attachment such as a crusher and a dismantling machine, and a hydraulic actuator provided on the work attachment.

  The background art will be described by taking as an example a dismantling machine with an ultra-long attachment used for dismantling high-rise buildings.

  As shown in FIG. 5, the dismantling machine includes a crawler-type lower traveling body 1 and a front portion of a base machine A comprising an upper revolving body 2 that is mounted on the lower traveling body 1 so as to be rotatable about a vertical axis. And a work attachment B having a long boom 3 is mounted.

  The boom 3 of this work attachment B has the first, second, third, and fourth stage boom bodies 4, 5, 6, and 7 in order from the bottom in relation to each other around the horizontal axis. A lower end portion of the first stage boom body 4 is attached to the upper swing body 2 of the base machine A.

  Further, first to fourth boom cylinders 8 to 11 are provided as cylinders for raising and lowering the boom bodies 4 to 7, and the entire boom 3 is raised and lowered by the first boom cylinder 8. The boom cylinders 9 to 11 cause the second to fourth step boom bodies 5 to 7 to bend and extend using the connecting portions as joints.

  An opening / closing type crushing device 12 as a working device is provided at the tip of the boom 3 (tip of the fourth-stage boom body 7), and the crushing device 12 crushes the concrete lump and the like to dismantle the building. Is called.

  In FIG. 5, reference numeral 13 denotes a crushing device cylinder that rotates the crushing device 12 up and down around a horizontal axis. Further, the crushing device 12 is configured to be rotatable so that the direction is variable, and is configured to be openable and closable for performing a crushing motion, and is rotated and opened and closed by a hydraulic motor and an open / close cylinder (not shown here). .

Such a dismantling machine is shown, for example, in Patent Document 1, and a hydraulic circuit of a boom-equipped working machine including the dismantling machine is shown in Patent Document 2, respectively.
Japanese Patent Laid-Open No. 7-305518 JP 2000-92706 A

  In a work machine equipped with such a long work attachment B, each hydraulic actuator (particularly the open / close cylinder and rotary motor on the front end side) provided on the work attachment B, a hydraulic pump mounted on the base machine A, and The oil supply line connecting the tank becomes very long and the pipe volume increases.

  Moreover, even if the actuator is operated, the movement of the actuator per operation is small and the movement of oil is small.

  Therefore, the oil in the oil supply line is not circulated, stays in the line, does not easily return to the tank, and is not cooled by the oil cooler, so that the oil temperature in the line tends to rise.

  For this reason, problems such as an adverse effect due to an increase in the oil temperature, such as the oil temperature exceeding the operating temperature limit of the seal in the open / close cylinder or the rotary motor, causing the seal to break and oil leakage have occurred.

  Therefore, the present invention provides a hydraulic circuit for a work machine that can prevent the oil temperature from rising by replacing the oil in the oil supply line.

  According to the first aspect of the present invention, a work attachment is attached to a base machine, and a hydraulic actuator provided on the work attachment is connected to a hydraulic pump and a tank mounted on the base machine by an oil supply line. In a hydraulic circuit of a work machine in which the operation of the hydraulic actuator is controlled by a control valve provided, a return line for returning the oil in the oil supply line to the tank and a return valve for opening and closing the return line are provided. is there.

  According to a second aspect of the present invention, in the configuration of the first aspect, the return line includes a main pipeline connected to the tank and two individual pipelines branched from the main pipeline and connected to the oil supply lines on both sides. In addition, a return valve is provided in the main pipeline, while a check valve that allows only the flow of oil from the oil supply line to the individual pipeline is provided in both the individual pipelines, and the control valve is opened with the return valve open. By operating, the oil in the oil supply line is returned to the tank via the return line.

  According to a third aspect of the present invention, in the configuration of the second aspect, the return valve is configured as an electromagnetic valve that is energized and opened by operation of a switch.

  According to a fourth aspect of the present invention, in the configuration of the second aspect, the return valve is configured as an interlocked valve with a throttle that opens when the valve is operated in conjunction with the control valve and raises pressure on the inlet side in the open state. It has been done.

  According to a fifth aspect of the present invention, in the configuration of the fourth aspect, the control valve and the return valve are configured as hydraulic pilot valves that are simultaneously operated by an operation valve that outputs a pilot pressure corresponding to an operation amount.

  According to a sixth aspect of the present invention, in the configuration of the first aspect, the return line includes a main line connected to a sub pump having a discharge pressure lower than that of a main pump serving as a hydraulic pressure source of the hydraulic actuator, and both sides branched from the main line. A check valve that consists of two individual pipes connected to the oil supply line, and a return valve is provided in the main pipe, while allowing only the oil flow from the main pipe to the oil supply line in both the individual pipes Is provided.

  According to a seventh aspect of the present invention, in the configuration of the sixth aspect, the control valve is configured as a hydraulic pilot valve that is operated by an operation valve that outputs a pilot pressure corresponding to an operation amount, and serves as a pilot pressure source of the operation valve. A hydraulic pump is used as a sub pump, and a return valve is provided with a throttle for ensuring the pilot pressure.

  According to an eighth aspect of the present invention, in the configuration of the first aspect, the return line is provided in a state where the both-side oil supply lines are short-circuited.

  According to the present invention, since the return line for returning the oil in the oil supply line to the tank is provided and the return line is configured to be opened and closed by the return valve, the oil in the oil supply line is actively returned (circulated) to the tank by the return line. Can be cooled.

  Specifically, in the second to fifth aspects of the invention, the oil in the oil supply line is returned to the tank via the return line by operating the control valve with the return valve opened. Among these, in claim 3, the return valve is opened by a switch operation, and in claims 4 and 5, the return valve is opened in conjunction with the control valve.

  In the inventions of claims 6 and 7, when oil is fed from the sub pump to the oil supply line via the return line, the oil in the oil supply line is forcibly returned to the tank via the line.

  In this case, since the discharge pressure of the sub pump is lower than the discharge pressure of the main pump, the oil from the sub pump is sent only to the return side (low pressure side) oil supply line. At this time, since the check valve of the individual pipe connected to the high-pressure side oil supply line is pushed closed by the pressure of the high-pressure side oil supply line, there is no possibility that oil flows into the return line from the high-pressure side oil supply line. Absent.

  According to the invention of claim 7, when the control valve is operated by the pilot pressure from the operation valve, a hydraulic pump serving as a pilot pressure source of the operation valve is used as a sub pump, so a return-only sub pump is added. This is advantageous in terms of cost, space, and the like. In this case, since the throttle is provided in the return valve, there is no problem that all the oil from the sub pump is sent to the return line and the pressure source of the operation valve is lost, and it is possible to secure the pilot pressure to be sent to the control valve. it can.

  On the other hand, according to the invention of claim 8, since the return line is provided in a state where both the oil supply lines are short-circuited, the oil in the high-pressure side oil supply line directly enters the low-pressure side oil supply line and returns to the tank. That is, the low pressure side oil supply line can be used as a part of the return line. For this reason, there is no need to provide a return-only line connecting the oil supply line and the tank.

  With the above invention, it is possible to prevent an increase in the oil temperature of the oil supply line and to avoid adverse effects such as breakage of the seal.

  In the following embodiments, the case where the present invention is applied to an open / close cylinder circuit that opens and closes the crushing device 12 in FIG. 5 is taken as an example.

1st Embodiment (refer FIG. 1)
The open / close cylinder 14 is connected to the main pump 15 and the tank T which are hydraulic sources mounted on the base machine A in FIG. 5 by two oil supply lines (extension side and contraction side oil supply lines) 16 and 17. The operation of the open / close cylinder 14 is controlled by a control valve 18 provided in the lines 16 and 17.

  The control valve 18 is configured as a hydraulic pilot valve, and is switched between a neutral position A, an extended position B, and a contracted position C by a pilot pressure output from the operating valve 19 according to the operation amount. 20 is a sub-pump as a pressure source of the operation valve 19, 21 and 22 are both expansion side and contraction side pilot lines connecting the operation valve 19 and both side pilot ports 18a and 18b of the control valve 18, and 23 is both side oil supply lines 16 and 17 This is a relief valve that sets the maximum pressure.

  Note that the discharge pressure of the sub pump 20 is set to a value lower than the discharge pressure of the main pump 15.

  In this open / close cylinder circuit, a return line 24 for returning the oil in the oil supply lines 16 and 17 to the tank T is provided.

  The return line 24 includes a main pipe 25 connected to the tank T, and two individual pipes branched from the main pipe 25 and connected to both side oil supply lines 16 and 17 (preferably close to the open / close cylinder 14). It consists of passages 26 and 27, and a return valve 28 is provided in the main pipeline 25.

  The return valve 28 is configured as an electromagnetic valve that is switched from the block position A to the open position B in the figure by closing the switch 29, and is installed in the base machine A.

  In addition, both individual pipes 26 and 27 are provided with check valves 30 and 31 that allow only the flow of oil from the oil supply lines 16 and 17 toward the individual pipes 26 and 27.

  On the other hand, oil temperature sensors 32 and 33 for detecting the oil temperature near the cylinders in the both-side oil supply lines 16 and 17 are provided, and the oil temperature detected by the oil temperature sensors 32 and 33 is displayed on a thermometer in the base machine A. Is done.

  In this configuration, when it is confirmed that the oil temperature in the oil supply lines 16 and 17 has risen to a predetermined value or more, the operation is interrupted, and the return valve 28 is opened by operating the switch 29.

  In this state, the control valve 19 is operated to switch the control valve 18 alternately between the expansion side and the contraction side positions B and C.

  In this way, for example, when the control valve 18 is operated to the extension side (extension position b), the oil from the main pump 15 is sent to the extension-side oil supply line 16 as shown by the broken line arrow in FIG. The oil in the line 16 flows into the return line 24 through the path of the individual pipe line 26 (check valve 30) and the main pipe line 25, and returns to the tank T through the return valve 28.

  At this time, since the pressure of the return line 24 is sufficiently lower than the pressure of the oil supply line 16 and the open / close cylinder 14 (becomes a value close to 0 due to only the pressure loss of the pipeline), no oil flows into the open / close cylinder 14. The cylinder 14 remains almost stopped.

  By performing this operation on the both-side oil supply line 17, the oil in the both-side oil supply lines 16, 17 can be forcibly circulated and the oil temperature can be lowered by a cooling action by passing an oil cooler and a tank T (not shown). .

  For this reason, adverse effects such as breakage of the seal of the open / close cylinder 14 due to an increase in the oil temperature can be avoided.

  The oil temperature sensors 32 and 33 are effective in accurately confirming the oil temperature, but the above circulating action may be performed when an increase in the oil temperature is predicted by the operator. This is the same in other embodiments.

Second embodiment (see FIG. 2)
In the following embodiments, the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description thereof is omitted.

  In the second embodiment, the return valve 28 is configured as a hydraulic pilot valve, and the return valve pilot line 34 for supplying pilot pressure to the return valve 28 is connected to the control valve pilot lines 21 and 22 via the shuttle valve 35. It is connected to the.

  That is, the return valve 28 is configured to open in conjunction with the control valve 18 by the pilot pressure from the operation valve 19.

  According to this configuration, part of the oil sent to the open / close cylinder 14 is returned to the tank T via the return line 24 when the control valve 18 is operated, that is, during operation. That is, the forced circulation of oil is always performed automatically during operation. Therefore, there is no need to interrupt the work as in the first embodiment.

  In this case, the return valve 28 is provided with a throttle restrictor 28 a for raising the pressure in the oil supply lines 16 and 17 so as not to flow into the return line 24.

  In this embodiment, regardless of the oil temperature, the oil circulating action is always performed during the operation, and therefore there is no need to monitor the oil temperature, so the oil temperature sensors 32 and 33 of the first embodiment are unnecessary. It becomes.

Third embodiment (see FIG. 3)
In the third embodiment, similar to the first embodiment, the return line 24 is connected to the sub pump 20 on the assumption that the operation is interrupted and the control valve 18 is operated to replace the oil in the oil supply lines 16 and 17. Connected to the discharge side, the discharge oil (low temperature oil) of the sub pump 20 is configured to be fed into the oil supply lines 16 and 17 through the return line 24.

  For example, when the control valve 18 is operated to the extension side (extension position b), the oil from the main pump 15 is sent to the extension side oil supply line 16, while the sub pump 20 of the sub-pump 20 is shown as indicated by the broken line arrow in FIG. The discharged oil is sent to the contraction side oil supply line 17 through the return line 24.

  By performing this operation also on the expansion side, the oil in the both-side oil supply lines 16 and 17 is replaced with the low-temperature oil from the sub-pump 20, and the oil temperature is prevented from rising.

  The return valve 28 is provided with a throttle 28b for securing the pilot pressure of the pilot lines 21 and 22.

  In addition, check valves 36 and 37 that allow only the flow of oil from the return line 24 toward the oil supply lines 16 and 17 are provided in both the individual pipelines 26 and 27 in the return line 24.

Fourth embodiment (see FIG. 4)
In each of the first to third embodiments, the return line 24 is provided between the oil supply lines 16 and 17 and the tank T or the sub pump 20, and the return valve 28 is installed in the base machine A in FIG. On the other hand, in 4th Embodiment, the return line 24 is provided in the state which short-circuits the both-side oil supply lines 16 and 17 in the front-end | tip part of the work attachment B, and the return valve 28 is also provided in the same line 24 in the attachment front-end | tip part. ing.

  The oil circulation operation and operation by this configuration are basically the same as those in the first embodiment. By interrupting the operation and operating the control valve 18, the oil in the high-pressure side of the oil supply lines 16 and 17 is discharged. The oil flows into the low-pressure side line via the return line 24 and returns to the tank T, where oil circulation (replacement of high temperature oil and low temperature oil) is performed.

  According to this configuration, the low-pressure side oil supply line can be used as a part of the return line. For this reason, it is not necessary to provide a long line exclusively for return connecting the oil supply lines 16 and 17 and the tank T as in the first to third embodiments. For this reason, the piping configuration is simplified and the cost is reduced.

  In this case, the return line 24 with the return valve 28 is preferably provided as close as possible to the opening / closing cylinder 14 for the purpose of protecting the seal of the opening / closing cylinder 14.

  By the way, as a modification of each of the first, third, and fourth embodiments, the oil temperature detected by the oil temperature sensors 32, 33 is a set value on condition that a circuit configuration that does not hinder the operation of the opening / closing cylinder 14 is taken. When it becomes above, you may comprise so that the return valve 28 may be opened automatically and oil circulation may be performed.

  In addition, the present invention is not limited to the open / close cylinder circuit, and other hydraulic actuators provided in the work attachment B, that is, a rotary motor or a crushing device cylinder 13 for rotating the crushing device 12 of FIG. 4 The present invention can also be applied to each circuit of each boom cylinder 9-11.

1 is a hydraulic circuit diagram showing a first embodiment of the present invention. It is a hydraulic circuit diagram which shows 2nd Embodiment of this invention. It is a hydraulic circuit diagram which shows 3rd Embodiment of this invention. It is a hydraulic circuit diagram which shows 4th Embodiment of this invention. It is a schematic side view of the demolition machine to which the present invention is applied.

Explanation of symbols

A Base machine B Work attachment 3 Boom 14 Open / close cylinder 15 Main pump T Tank 16, 17 Refueling line 18 Control valve 19 Operation valve 20 Sub pump 21, 22 Pilot line 24 Return line 25 Main line 26, 27 Individual line 28 Return valve 28a , 28b Throttle 29 Switch 30, 31 Check valve 34 Return valve pilot line 35 Shuttle valve 36, 37 Check valve

Claims (8)

  A work attachment is attached to the base machine, and a hydraulic actuator provided on the work attachment is connected to a hydraulic pump and a tank mounted on the base machine via an oil supply line, and the hydraulic pressure is controlled by a control valve provided on the oil supply line. In a hydraulic circuit of a work machine in which operation of an actuator is controlled, a return line for returning oil in the oil supply line to the tank and a return valve for opening and closing the return line are provided. circuit.   The return line is composed of a main pipeline connected to the tank and two individual pipelines branched from the main pipeline and connected to the oil supply lines on both sides. A return valve is provided in the main pipeline, A check valve that allows only the flow of oil from the oil supply line to the individual pipe is provided in the individual pipe line, and the control valve is operated with the return valve open, so that the oil in the oil supply line passes through the return line. The hydraulic circuit for a working machine according to claim 1, wherein the hydraulic circuit is configured to be returned to the tank.   3. The hydraulic circuit for a working machine according to claim 2, wherein the return valve is configured as an electromagnetic valve that is energized and opened by operating a switch.   3. The work machine according to claim 2, wherein the return valve is configured as an interlocked valve with a throttle that opens when the valve is operated in conjunction with the control valve and raises pressure on the inlet side in the open state. Hydraulic circuit.   5. The hydraulic circuit for a work machine according to claim 4, wherein the control valve and the return valve are configured as hydraulic pilot valves that are simultaneously operated by an operation valve that outputs a pilot pressure corresponding to an operation amount.   The return line consists of a main line connected to a sub pump whose discharge pressure is lower than that of the main pump serving as the hydraulic source of the hydraulic actuator, and two individual lines branched from this main line and connected to the oil supply lines on both sides. 2. A return valve is provided in the main pipeline, and a check valve that allows only an oil flow from the main pipeline to the oil supply line is provided in each of the individual pipelines. Hydraulic circuit of work machine.   The control valve is configured as a hydraulic pilot valve that is operated by an operation valve that outputs a pilot pressure corresponding to the operation amount, and a hydraulic pump that serves as a pilot pressure source of the operation valve is used as a sub pump, and the return valve The hydraulic circuit for a working machine according to claim 6, further comprising a throttle for securing the pilot pressure.   2. The hydraulic circuit for a work machine according to claim 1, wherein the return line is provided in a state in which the both-side oil supply lines are short-circuited.

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