JP2005264605A - Malfunction prevention of work machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent the malfunction of an actuator when a start operation is performed in the state of an operating member not set at a neutral position by a simple and low cost structure. <P>SOLUTION: A control valve 18 comprises a lock selector valve 30 in a circuit for supplying a pilot pressure and a lock operation means 31 operating the valve 30. The lock selector valve 30 comprises a lock position for forcibly cutting off the supply of the pilot pressure. The lock operation means 31 sets the lock position of the lock selector valve 30 when an operation rest lever 38 is at an operation rest position as well as when an operation lever 20 is not at the neutral position to prevent the malfunction of the actuator 16 or prevent the malfunction by restricting the flow of a hydraulic oil supplied from a hydraulic pump 12 to the control valve 18. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for preventing an actuator operation unintended by an operator at the start of operation in a work machine such as a hydraulic excavator.

  In a work machine in which hydraulic pressure supply from a hydraulic pump to an actuator is operated by operating an operation member such as an operation lever, the actuator may be unexpectedly operated due to an erroneous operation of the operation member. For example, if the operator accidentally touches the operation member when getting on and off while the engine is operating, or if the engine is started without the operator recognizing that the operation member is out of the neutral position, the operation member There is a risk that the actuator will behave unexpectedly corresponding to the position of. Therefore, various measures for preventing such malfunction of the actuator have been studied.

  For example, Patent Document 1 below discloses a device that prevents malfunction of an actuator using an operation stop lever provided in a cab. The outline of this apparatus is as follows.

  A control valve comprising a pilot switching valve is provided between the actuator and the hydraulic pump. In addition to the remote control valve having the operation lever, the control valve is provided in a circuit for supplying pilot pressure to the control valve. An operation stop valve (lock switching valve) for forcibly shutting off the supply of the pilot pressure to is provided. The operation stop valve is composed of an electromagnetic switching valve, and is configured to allow the supply only when the solenoid is excited. An operation stop switch is provided between the solenoid and the power source. Yes.

  On the other hand, the operation stop lever is provided in the driver's cabin together with the operation lever, and can be switched between an operation stop position for opening the boarding / alighting path for the driver's seat and an operation position for blocking the boarding / alighting path. The operation stop switch opens and closes in conjunction with the operation stop lever.

  In this device, after the operator switches the operation stop lever to the operation stop position and gets on the driver's seat, the actuator is not operated unless the engine is started after switching the lever to the operation position again. That is, when the operation stop lever is in the operation stop position, the operation stop switch is open and power is not supplied to the solenoid of the operation stop valve, so that the operation stop valve is controlled regardless of the operation position of the operation lever. Therefore, when the engine is started in this state, the actuator does not operate regardless of the operation position of the operation lever. Therefore, it is possible to prohibit unexpected operation of the actuator due to erroneous operation of the operation lever when the operator gets on and off.

  However, with only the configuration described above, if the operation stop lever is erroneously operated after switching to the operation position, for example, the operator's clothes may be caught on the operation member, and the operation member may accidentally come off the neutral position. If this happens, the actuator may malfunction if the operator starts the engine without knowing it.

Therefore, in the apparatus described in Patent Document 1, an electromagnetic switching valve is also provided between the remote control valve and the control valve, and when the operation start operation is performed in a state where the operation member is not in a neutral position. A measure is taken to prevent the malfunction by closing the electromagnetic switching valve to forcibly cut off the supply of pilot pressure to the control valve.
JP 2000-104291 A

  In the device described in Patent Document 1, an operation stop valve (lock switching valve) is interposed between the remote control valve and a pilot pump as a pilot pressure supply source, and the operation member is not in a neutral position. As a means for preventing malfunction when the engine is started, an electromagnetic switching valve is also interposed between the remote control valve and the control valve. Therefore, as the number of switching valves used increases, Therefore, the circuit and wiring for this are complicated, and the cost is generally high. Further, the assembling work and the maintenance work are complicated by the increase of the electromagnetic switching valve.

  The present invention aims to solve such problems.

  As means for solving the above-mentioned problems, the present invention relates to a working machine including a hydraulic pump driven by an engine and an actuator that operates by receiving hydraulic oil supplied from the hydraulic pump. Engine operation detecting means for detecting whether or not the engine is in operation, and interposed between the hydraulic pump and the actuator, and receiving a pilot pressure from a pilot pressure supply source, the hydraulic pump to the actuator A control valve that can be switched from a shut-off position that shuts off the hydraulic oil supply path to an open position that opens the supply path, an operating member for operating the supply of the pilot pressure to the control valve, and an operation of the operating member Pilot pressure operating means for changing the supply state of the pilot pressure according to the position; and Neutral position detecting means for detecting whether or not the operation position of the member is in a neutral position for causing the control valve to be in the shut-off position; and forcibly halting the operation of the actuator regardless of the operation position of the operation member An operation stop switching member that is switched to an operation stop position for enabling the operation of the actuator, an operation stop switching detecting means for detecting the switching position of the operation stop switching member, and the control valve Between the pilot pressure supply source and the pilot pressure supply source, and allows the pilot pressure to be supplied from the pilot pressure supply source to the control valve regardless of the operation position of the operation member. A lock switching valve that is switched to an unlocking position, and at least the lock switching valve It is obtained and a lock operation means for performing serial operations a to c.

  Operation a. When the operation stop switching member is in the operation stop position, the lock switching valve is set to the lock position.

  Operation b. A state where the engine is operating and the operation stop switching member is in the operation position is an operation permission state, and when the operation is in an operation permission state, the lock switching valve is set to the unlock position.

  Operation c. Even when in the operation permission state, when it is detected that the operation member is not in the neutral position at the time when the operation start operation for switching from the state that is not the operation permission state to the operation permission state is performed, the lock switching valve To the locked position.

  Here, the operation b is not intended to always set the lock switching valve to the locked position when the operation is not permitted. Therefore, when the operation suspension switching member is switched to the operation position, the lock switching valve may be switched to the unlock position even when the engine is not operating, or the operation suspension switching member is switched to the operation position. It is also possible to switch to the unlock position only when the engine is operating.

  In the above configuration, when the operation stop switching member is switched to the operation stop position, the lock switching valve is in the lock position, forcibly shutting off the supply of pilot pressure from the pilot pressure supply source to the control valve, and the operation member Since the operation of the control valve is locked, malfunction of the actuator due to erroneous operation of the operation member is prevented. On the other hand, when the engine is operated and the operation stop switching member is in the operation permitted state in the operation position, the lock switching valve is switched to the unlock position in principle, and the pilot pressure supply source to the control valve Therefore, it is possible to operate the actuator by operating the control valve with the operating member.

  However, when it is detected that the operation member is not in the neutral position at the time when the operation start operation for switching from the state that is not the operation permitted state to the operation permitted state is performed even in the operation permitted state, Since the lock switching valve is switched to the lock position, for example, when the operator performs the operation start operation without recognizing that the operation member is not in the neutral position, the actuator is prevented from unexpectedly operating. The

  In this way, when the common lock switching valve locks the operation member when the operation suspension switching member is in the operation suspension position, and the operation start operation is performed without the operation member being in the neutral position. Therefore, the malfunction of the actuator can be effectively prevented with a simple and low-cost configuration.

  Further, the lock operation means locks the lock switching valve when it is detected that the operation member is not in the neutral position from when the operation start operation is performed until a specific time elapses. As long as the operation member is not in the neutral position before the operation start operation is performed, the operation member is erroneously operated from the neutral position slightly after the operation start operation. In addition, it is possible to prevent an unexpected operation of the actuator due to the erroneous operation.

  The neutral position detection means may directly detect the operation position of the operation member, for example, but it detects a pilot pressure such as a pressure switch that detects whether a pilot pressure higher than a specific pressure is supplied to the control valve. It is also possible to use the means as the neutral position detecting means. In this case, when the operation start operation is performed, the lock operation means once switches the lock switching valve to the unlock position and until a specific time elapses from the time of switching to the unlock position. During this time, the lock switching valve may be returned to the lock position when it is detected that a pilot pressure higher than the specific pressure is supplied to the control valve.

  In addition, the lock operation means is configured to turn the lock switching valve when a specific unlocking operation is performed in a state where the lock switching valve is in the locked position even though the operation permission condition is satisfied. It is more preferable to switch to the unlock position.

  As the “unlock operation” in this case, for example, an operation of once operating the operation stop switching member to the operation position and switching to the operation stop position again, or an operation of stopping the engine and then starting it again is set. For example, the lock operation by the lock operation means can be released using existing components without adding a special switch or the like.

  As a specific configuration of the lock switching valve and the lock operation means, for example, the lock switching valve is an electromagnetic switching valve, and the lock operation means is a power source that supplies an excitation current to the solenoid of the electromagnetic switching valve; Intervening between the power supply and the solenoid, in conjunction with the operation of the operation stop switching member so that the lock switching valve is switched to the lock position when the operation stop switching member is in the operation stop position. An operation stop changeover switch that opens and closes, and the lock changeover valve regardless of whether the operation stop changeover switch is open or closed when it is detected that the operation member is not in the neutral position when the operation start operation is performed. It is preferable to include a forcible lock means for switching the conduction state between the power source and the solenoid so that the power is in the locked position.

  According to this configuration, the operation stop changeover switch can be used as the means for performing the operation a and the operation stop changeover detection means. In addition, even if an operation failure occurs in the forced lock means, The malfunction prevention function for performing the operation of switching the lock switching valve to the lock position when the operation a, that is, the operation stop switching member is operated to the operation stop position is ensured.

  Further, the present invention provides an engine for detecting whether or not the engine is operating in a work machine including a hydraulic pump driven by the engine and an actuator that operates by receiving hydraulic oil supplied from the hydraulic pump. An operation detecting means and a shutoff that is interposed between the hydraulic pump and the actuator and shuts off a hydraulic oil supply path from the hydraulic pump to the actuator by receiving a pilot pressure supplied from a pilot pressure supply source. A control valve that is switched from a position to an open position that opens the supply path, an operating member for operating the supply of the pilot pressure to the control valve, and the supply of the pilot pressure according to the operating position of the operating member The pilot pressure operating means for changing the state and the operating position of the operating member are A neutral position detecting means for detecting whether or not the valve is in the neutral position, and an operation pause position for forcibly stopping the operation of the actuator regardless of the operation position of the operation member; The operation stop switching member that is switched to the operation position for releasing the forced stop, the operation stop switching detecting means that detects the switching position of the operation stop switching member, and the operation stop switching member are in the operation stop position. Locking means for disabling operation of the actuator by operation of the operating member, flow rate operating means for changing a pump flow rate that is a supply flow rate of hydraulic oil from the hydraulic pump to the control valve, and the engine operating And when the operation start operation is performed to bring the operation stop switching member to the operation position, the operation member is moved forward. When it is detected not in the neutral position is obtained by a flow control means for operating said flow operating means to regulate flow rates up to preset the pump flow.

  Also in this invention, the operation of the engine is not necessarily a necessary condition for making the pump flow rate the operation flow rate. Therefore, when the operation stop switching member is switched to the operation position, the pump flow rate may be changed to the operation flow rate regardless of the operating state of the engine, or the operation stop switching member is switched to the operation position, In addition, the operation flow rate may be set only when the engine is operating.

  In the above configuration, when the operation stop switching member is switched to the operation stop position, the lock means disables the operation of the actuator by operating the operation member, so that the operation member is operated by mistake. Is prevented from malfunctioning. Further, when it is detected that the operation member is not in the neutral position when the engine is started and the operation start operation in which the operation stop switching member is in the operation position is performed, the pump flow rate is increased to a preset flow rate. Therefore, for example, an erroneous operation of the actuator when the operator performs the operation start operation without recognizing the operation position of the operation member is effectively suppressed.

  That is, in this apparatus, the pump flow rate is regulated so that the movement of the actuator is suppressed when the operation start operation is performed in a state where the operation member is not in the neutral position. Thus, malfunction of the actuator can be avoided.

  As the locking means, for example, the flow rate control means may be configured to restrict the pump flow rate to a preset flow rate when the operation stop switching member is in the operation stop position, A lock switching valve that forcibly shuts off the supply of pilot pressure to the control valve regardless of the operation position of the operation member when the operation suspension switching member is in the operation suspension position may be included. In the former case, it is possible to omit the lock switching valve, whereby the configuration can be further simplified and the cost can be reduced.

  Furthermore, when the flow rate control means detects that the operation member is not in the neutral position between the time when the operation start operation is performed and the elapse of a specific time, the pump flow rate is preset. As long as the flow rate operation means is operated so as to regulate the flow rate, not only when the operation member is not in a neutral position before the operation start operation is performed, the operation member is slightly delayed from the operation start operation. Even if the actuator is erroneously operated from the neutral position, it is possible to prevent unexpected operation of the actuator due to the erroneous operation.

  In addition, the flow rate control means uses the pump flow rate for the operation when a specific deregulation operation is performed in a state where the pump flow rate is regulated to the regulated flow rate even though the operation is permitted. More preferably, the flow rate operating means is operated so as to switch to a flow rate.

  As the “regulation release operation” in this case, for example, an operation of once operating the operation stop switching member to the operation position and switching to the operation stop position again, or an operation of stopping the engine and then starting it again is set. For example, the lock operation by the lock operation means can be released using an existing component without adding a special switch or the like.

  The pump flow rate may be adjusted by, for example, bleed-off control using a flow control valve in the hydraulic circuit, but if the capacity of the variable displacement hydraulic pump is changed, the actuator can be configured with a simpler configuration. Can be prevented from malfunctioning.

  As described above, according to the present invention, the lock switching valve for forcibly shutting off the pilot pressure supply to the control valve when the operation stop switching member is in the operation stop position, or the hydraulic oil from the hydraulic pump to the control valve. By using the flow rate operation means for operating the supply flow rate of the actuator, it is possible to prevent the malfunction of the actuator when the operation start operation is performed without the operation member being in the neutral position with a simple and low-cost configuration. There is.

  A first embodiment of the present invention will be described with reference to FIGS.

  The apparatus shown in FIG. 1 is incorporated in a work machine on which an engine 10 is mounted, and includes a main hydraulic pump 12 and a pilot hydraulic pump 14 driven by the engine 10, and a hydraulic motor 16 that is an actuator. Yes.

  The present invention can be applied to prevent malfunction of actuators other than the hydraulic motor 16, such as hydraulic cylinders. The same applies to work machines in which hydraulic oil is distributed from a common hydraulic pump to a plurality of actuators.

  An alternator 44 is connected to the engine 10, and the alternator 44 is driven by the engine 10 to generate electric power. An engine oil pressure switch 11 for detecting the pressure of the engine oil is provided as an engine operation detecting means, and it is possible to recognize whether or not the engine 10 is operating based on an output signal of the engine oil pressure switch 11.

  Note that, as means for detecting the operation of the engine, an output signal of the alternator 44 as an engine speed sensor may be used.

  In this embodiment, the main hydraulic pump 12 is a variable displacement hydraulic pump. The capacity is operated by the electromagnetic proportional pressure reducing valve 42 using the oil discharged from the pilot hydraulic pump 14. A command signal output from a controller 40 (described later) is input to the solenoid 42a of the electromagnetic proportional pressure reducing valve 42, whereby the set pressure operation of the electromagnetic proportional pressure reducing valve 42 is performed.

  A control valve 18 is interposed between the main hydraulic pump 12 and the hydraulic motor 16. The control valve 18 is composed of a hydraulic pilot switching valve and has a pair of pilot portions 18a and 18b. When no pilot pressure is supplied to any of the pilot portions 18a and 18b, the shutoff position for shutting off the hydraulic oil supply path from the main hydraulic pump 12 to the hydraulic motor 16 is maintained, while any pilot portion 18a, When the pilot pressure is supplied to 18b, the valve is opened by a stroke corresponding to the pilot pressure in the direction corresponding to the pilot portion. That is, it is switched to an opening position for opening the supply path.

  The pilot pressure is supplied to the pilot portions 18a and 18b through the remote control valve 20 from the pilot hydraulic pump 14 which is a pilot pressure supply source.

  The remote control valve 20 has an inlet port and a pair of outlet ports, the inlet port is connected to the discharge side of the pilot hydraulic pump 14 via an oil passage 28, and the pair of outlet ports are oil passages 24A, 24A, respectively. The pilot parts 18a and 18b are connected via 24B.

  The remote control valve 20 has an operation lever 22 which is an operation member, and the operation lever 22 is arranged in the driver's cab. When the operation lever 22 is in the neutral position, supply of pilot pressure from the pilot hydraulic pump 14 to the pilot portions 18a and 18b is cut off, while when the operation lever 22 is operated from the neutral position, A pilot pressure having a magnitude corresponding to the operation amount is supplied to the pilot portion 18a (or pilot portion 18b) through the oil passage 24A (or oil passage 24B) connected to the outlet port from the outlet port corresponding to the operation direction. .

  The oil passages 24A and 24B are provided with pressure switches 26A and 26B as pilot pressure detecting means. These pressure switches 26A and 26B are switched from off to on when the pilot pressure in the oil passages 24A and 24B exceeds a certain level, and output detection signals.

  Further, a lock switching valve 30 is provided in the middle of the oil passage 28. In the illustrated example, the lock switching valve 30 is constituted by an electromagnetic switching valve having a solenoid 30a. When the excitation current is not supplied to the solenoid 30a, the lock switching valve 30 is switched to the lock position A, and the excitation current is supplied to the solenoid 30a. It is switched to the unlock position b. The lock position a is a position where the oil passage 28 is forcibly blocked and the input port of the remote control valve 20 is communicated with the tank to prevent the pilot pressure supply from the pilot hydraulic pump 14 to the remote control valve 20. The unlock position B is a position where the oil passage 28 is opened and the pilot pressure supply is allowed.

  The lock switching valve 30 is opened / closed by a lock operating means 31. The lock operation means 31 includes a battery 32, a power switch 34, an operation suspension changeover switch 36, a forced lock switch 39, and a controller 40.

  The battery 32 stores the electric power generated by the alternator 44, and serves as a power source for supplying an exciting current to the solenoid 30a of the lock switching valve 30. Between the battery 32 and the solenoid 30a, the power switch 34, the operation stop changeover switch 36, and the forced lock switch 39 are arranged in series in this order from the side closer to the battery 32.

  The power switch 34 is provided in the cab and is manually opened and closed. Information about the open / closed state of the power switch 34 is input to the controller 40.

  The operation stop changeover switch 36 opens and closes in conjunction with the operation of an operation stop lever (operation stop changeover member) 38.

  This operation stop lever 38 is provided in the driver's cab and is operated up and down between an operation position indicated by a two-dot chain line in FIG. 1 and an operation stop position indicated by a solid line in FIG. The driving position is a position where the boarding road to the driver's seat in the driver's cab is cut off substantially horizontally, and the driving stop position is a position where the driving board is opened by avoiding upward from the driving position. is there.

  The operation stop changeover switch 36 is connected to the operation stop lever 38 through an appropriate interlocking mechanism. When the operation stop lever 38 is in the operation position, the operation stop changeover switch 36 is closed (that is, the battery 32 and the solenoid 30a). When the operation stop lever 38 is in the operation stop position, it is switched to the open position (that is, the position where the connection between the battery 32 and the solenoid 30a is cut off). Information about the open / closed state of the operation stop changeover switch 34 is also input to the controller 40.

  The forced lock switch 39 is constituted by a relay switch and is remotely opened and closed by an operation signal output from the controller 40. When the forced lock switch 39 is opened, the solenoid 30a is disconnected from the battery 32 regardless of the open / close state of the operation stop switch 34 (that is, regardless of the position of the operation stop lever 38), and the lock switch valve 30 is It is held in the locked position (a).

  The controller 40 is constituted by a microcomputer or the like, and opens / closes the forced lock switch 39 based on output signals of the engine hydraulic switch 11 and the pressure switches 26A and 26B, open / close information signals of the power switch 34 and the operation stop switch 36, and the like. Operation and opening operation of the electromagnetic proportional pressure reducing valve 42 are performed.

  Specifically, the controller 40 closes the forced lock switch 39 only when the operation stop changeover switch 36 is closed (that is, when it is detected that the operation stop lever 38 is in the operation position). Otherwise, the switch 39 is opened.

  Further, as a feature of this apparatus, the controller 40 detects that the engine 10 is operated by the engine hydraulic switch 11 (or the alternator 44) even when the operation suspension changeover switch 36 is closed. And when the operation stop changeover switch 36 is switched to the permitted operation state, that is, when the operation start operation for switching from the non-operation permitted state to the permitted operation state is performed. When it is detected that the lever 22 is not in the neutral position, the forced lock switch 39 is opened.

  That is, the controller 40 constitutes a forced lock means together with the forced lock switch 39.

  The detection that the operation lever 22 is not in the neutral position will be described in detail later.

  Next, the malfunction prevention operation performed in this apparatus will be described with reference to the flowchart of FIG. 2 and the time charts of FIGS.

  First, when the power switch 34 is turned on (step S1 in FIG. 2), the controller 40 opens the forcible lock switch 39 to shut off the solenoid 30a of the lock switching valve 30 from the battery 32, and the lock switching valve 30 is locked. (B) (step S2).

  In this state, since the space between the pilot hydraulic pump 14 and the input port of the remote control valve 20 is blocked by the lock switching valve 30, the control valve 18 is maintained at the blocking position regardless of the operation position of the operation lever 22. Therefore, the hydraulic motor 16 does not operate.

  After that, as shown in FIG. 3A, as the operation start operation, the engine 10 is first started (YES in step S3 in FIG. 2), and then the operation stop changeover switch 36 is closed, that is, the operation stop lever 38. When the operation for switching the operation position to the operation position is performed (YES in step S4), the controller 40 waits for a preset time T1 seconds from the time when the operation suspension changeover switch 36 is closed (YES in step S5). The forced lock switch 39 is closed (step S6). At this time, since the operation stop changeover switch 36 and the power switch 34 are also closed, an excitation current is supplied from the battery 32 to the solenoid 30a to turn on the solenoid 30a (FIG. 3A), and the lock changeover valve 30 is switched from the lock position a to the unlock position b.

  Since this unlock position is a position that allows the supply of pilot pressure from the pilot hydraulic pump 14 to the remote control valve 20, if the operation lever 22 is temporarily switched to the unlock position b, the operation lever 22 is in the neutral position. Otherwise, the pilot pressure rises in either of the oil passages 24A and 24B, and the pressure switches 26A and 26B are switched from OFF to ON (solid line in FIG. 3A).

  Therefore, the controller 40 continues until T2 seconds, which is a preset time, elapses from the time when the lock switching valve 30 is switched from the lock position A to the unlock position B (NO in step S10 in FIG. 2). The output signals of the pressure switch 26A and the pressure switch 26B are monitored, and when one of the pressure switches is turned on, it is determined that the operation lever 22 is not in the neutral position (NO in step S7), and the forced lock switch By opening 39, the lock switching valve 30 is returned to the lock position a. By this locking operation, the pilot pressure of the control valve 18 is forcibly lowered and the control valve 18 is returned to the shut-off position. Therefore, the malfunction of the hydraulic motor 16 due to the fact that the operation lever 22 is not in the neutral position is prevented.

  The “T2 seconds” is appropriately set in consideration of the time required for the pilot pressure to rise and the pressure switch 26A or the pressure switch 26B to be turned on after the lock switching valve 30 is switched to the unlock position B. Good. If this “T2 second” is set to be long, not only when the operation lever 22 is not in the neutral position at the time of the operation start operation, but also when the operation lever 22 is erroneously operated slightly after the operation start operation. It becomes possible to prevent the hydraulic motor 16 from malfunctioning by forcibly locking it.

  This forced lock state is released by the operator performing a specific lock release operation. In this embodiment, as the unlocking operation, an operation of once returning the operation stop lever 38 to the operation stop position (NO in step S9) and switching to the operation position again (YES in step S6) is set. By this operation, the operation after step S5 is resumed.

  In addition, as this unlocking operation, an operation of restarting the engine 10 after it is stopped and an operation of returning the operation lever 22 to the neutral position may be set. In the latter case, for example, a limit switch for directly detecting the operation position of the operation lever 22 may be provided as the neutral position detection means.

  If neither of the pressure switches 26A, 26B is switched on until the time T2 seconds elapses from the time of switching to the unlock position (step S6), that is, if the pilot pressure does not rise, at least It is determined that the operation lever 22 was in the neutral position at the start of operation (YES in steps S7 and S10), and the controller 40 keeps the forced lock switch 39 closed and moves the lock switching valve 30 to the unlock position B. keep. Accordingly, when the operation lever 22 is operated after the lapse of T2 seconds, the pilot pressure in the oil passage (oil passage 24A or oil passage 24B) corresponding to the direction of the operation rises (the bottom two stages in FIG. 3A). The control valve 18 is switched to the open position, and the hydraulic motor 16 operates. That is, normal operation of the hydraulic motor 16 is allowed.

  This operation permissible state is maintained until the operation stop lever 38 is switched to the operation stop position. That is, when the operation stop lever 38 is switched from the operation position to the operation stop position in the operation permissible state (NO in step S11), the controller 40 opens the forced lock switch 39 and switches the lock switching valve 30 to the lock position a. (Step S12).

  On the other hand, when the operation stop lever 38 is switched to the operation position and the operation stop changeover switch 36 is closed before starting the engine 10 (NO in step S3 and YES in step S13), this is also shown in FIG. Thus, the controller 40 immediately closes the forcible lock switch 39 at that time to make the battery 32 and the solenoid 30a conductive (step S14), and switches the lock switching valve 30 to the unlock position b. Thereafter, from the time when the engine 10 is started (YES in step S15), monitoring of the pilot pressure after step S7 is started in the same manner as described above.

  According to this device, using the common lock switching valve 30, the operation lock when the operation stop lever 38 is in the operation stop position and the operation start operation when the operation lever 22 is not in the neutral position are performed. Both of the operation locks can be performed, and the malfunction of the hydraulic motor 16 as the actuator can be effectively prevented with a simple and low-cost configuration.

  In the illustrated apparatus, the forced lock switch 39 is opened when the operation stop lever 38 is at the operation stop position. However, since the operation stop switch 36 is also open at this time, the forced lock switch 39 is not necessarily provided. It does not have to be opened. That is, the forced lock switch 39 may be opened only when the operation start operation is performed in a state where the operation lever 22 is not in the neutral position.

  Further, as the forced lock means, the operation suspension changeover switch 36 may be used instead of the forced lock switch 39. For example, when the operation stop change switch 36 is electrically operated and the operation start operation is performed in a state where the operation lever 22 is not in the neutral position, the operation stop change switch 36 is forcibly set regardless of the position of the operation stop lever 38. You may make it open.

  The operation stop changeover switch 36 does not necessarily have to be interposed between the battery 32 and the solenoid 30a, and may be used only as an operation stop change detection means. However, if the operation stop changeover switch 36 is interposed between the battery 32 and the solenoid 30a as shown in the drawing, the controller 40 and the forced lock switch 39 will malfunction and the switch 39 will remain closed. However, when the operation stop selector switch 36 opens and closes in response to the operation of the operation stop lever 38, at least the malfunction of switching the lock switching valve 30 to the lock position A when the operation stop lever 38 is in the operation stop position. Prevention function is ensured.

  Next, a second embodiment will be described.

  In this embodiment, the overall circuit diagram is substantially the same as that shown in FIG. However, the lock switching valve 30 and the forced lock switch 39 shown in the figure are omitted, and the discharge oil of the pilot hydraulic pump 14 is directly supplied to the input port of the remote control valve 20. The controller 40 is provided with a function as a capacity control means as a malfunction prevention means in place of the lock switching valve 30.

  That is, the controller 40 is based on the output signals of the engine oil pressure switch 11 and the pressure switches 26A and 26B, the open / close information signal of the power switch 34 and the operation stop changeover switch 36, etc. By changing the exciting current input to the solenoid 42a, the capacity of the main hydraulic pump 12, and hence the pump flow rate, that is, the supply flow rate of hydraulic oil from the main hydraulic pump 12 to the control valve 18 is adjusted.

  Specifically, the controller 40 performs the following control operation.

  The main hydraulic pump 12 is only operated when the engine 10 is in operation and the operation stop changeover switch 36 is closed (that is, it is detected that the operation stop lever 38 is in the operation position). While the tilt angle of the pump is increased to an appropriate angle and the pump flow rate is increased to a normal flow rate (operating flow rate) at which the hydraulic motor 16 can be operated, the tilt angle is minimized when the operation is not permitted. Thus, the pump flow rate is set to a regulated flow rate lower than the normal flow rate. The flow rate may be a flow rate at which the hydraulic motor 16 does not move even when the control valve 18 is opened, or is extremely low speed and substantially inoperable. In this embodiment, the minimum flow rate, that is, the main hydraulic pump 12 is used. The flow rate is set when the tilt angle is minimized.

  Further, the controller 40 detects that the operation lever 22 is not in the neutral position when the operation start operation for switching from the non-operation permitted state to the operation permitted state is performed even in the operation permitted state. In such a case, the pump flow rate is configured to be the minimum flow rate.

  The “normal flow rate”, that is, the operation flow rate may be any flow rate that substantially allows the hydraulic motor 16 to operate, and may be fixed to a constant flow rate, for example, the operation position of the operation lever 22. It may be increased or decreased within a suitable range according to the operation speed.

  The detection that the operating lever 22 is not in the neutral position is exactly the same as in the first embodiment.

  Next, the malfunction prevention operation performed in this apparatus will be described with reference to the flowchart of FIG. 4 and the time charts of FIGS.

  First, when the power switch 34 is turned on (step S21 in FIG. 4), the controller 40 sets the pump flow rate to the minimum flow rate by operating the electromagnetic proportional switching valve 42 (step S22). In this state, even if the operation lever 22 is operated to open the control valve 18, the hydraulic motor 16 hardly operates because the pump flow rate is extremely small.

  Thereafter, as the operation start operation, as shown in FIG. 5A, the engine 10 is first started (YES in step S23 in FIG. 4), and then the operation stop changeover switch 36 is closed, that is, the operation stop lever 38. Is switched to the operating position (YES in step S24), or the operation pause lever 38 is first switched to the operating position (YES in step S24), and then the engine is started (YES in step S23). It is monitored whether the pressure switch 26A or the pressure switch 26B is not turned on until T2 seconds, which is a preset time, elapses after the operation start operation (NO in step S26 in FIG. 4). When the switch is turned on, it is determined that the operation lever 22 is not in the neutral position (NO in step S25), and the pump flow rate is reduced to the minimum flow rate. Keep on (step S27). Therefore, the malfunction of the hydraulic motor 16 due to the operation start operation being performed in a state where the operation lever 22 is not in the neutral position is prevented.

  This flow rate regulation state is released by the operator performing a specific regulation release operation. In this embodiment, similar to the unlocking operation in the first embodiment, the operation suspension lever 38 is temporarily returned to the operation suspension position (NO in step S28) and then switched to the operation position again (YES in step S24). ) The operation is set as a restriction release operation, and the operation after step S25 is resumed by this operation. As in the case of the unlocking operation, the restriction releasing operation may be set such that the engine 10 is stopped and then restarted, or the operation lever 22 is returned to the neutral position.

  If neither of the pressure switches 26A and 26B is switched on during the time T2 seconds elapses after the operation start operation, that is, if the pilot pressure does not rise, the operation lever 22 is moved within the T2 seconds. It is determined that the neutral position has been maintained (YES in steps S25 and S26), and the controller 40 increases the pump flow rate to the normal flow rate (step S29). Therefore, when the operation lever 22 is operated and the control valve 18 is switched to the open position after T2 seconds have elapsed, the hydraulic oil is supplied to the hydraulic motor 16 at a flow rate corresponding to the stroke, and the motor 16 is operated. That is, normal operation of the hydraulic motor 16 is allowed.

  This operation permission state is maintained until the operation stop lever 38 is switched to the operation stop position. That is, when the operation stop lever 38 is switched from the operation position to the operation stop position in the operation permissible state (NO in step S30), the controller 40 reduces the pump flow rate to the minimum flow rate again (step S22).

  According to this device, the operation lock when the operation stop lever 38 is in the operation stop position and the operation lever 22 are not in the neutral position by using only the displacement operation of the main hydraulic pump 12 without using the lock switching valve 30. Thus, it is possible to perform both the operation lock when the operation start operation is performed, and to effectively prevent the malfunction of the hydraulic motor 16 as the actuator with a simple and low-cost configuration.

  The operation of the pump flow rate is not limited to the operation of the capacity of the main hydraulic pump 12, but the pump flow rate is regulated by performing bleed-off control using a flow rate control valve provided in the hydraulic circuit, for example. You may do it.

  Further, in the present invention, it is possible to take a form in which the forced lock by the lock switching valve 30 and the flow rate regulation by the capacity operation of the main hydraulic pump 12 are combined. In that case, as the third embodiment, the operation stop changeover switch 36 provided in the power supply circuit for the lock changeover valve 30 of the apparatus shown in FIG. 1 is left and only the forced lock switch 39 in the same circuit is omitted. As a general rule, the controller 40 controls the pump flow rate to be a normal flow rate (step S22 'in FIG. 6), and only when the operation start operation is performed with the operation lever 22 not in the neutral position. What is necessary is just to comprise so that control which makes a flow volume the minimum flow volume may be performed.

  In this embodiment, when the operation stop lever 38 is switched to the operation stop position (NO in steps S24, S28, S30, respectively), the operation stop switch 36 is opened and the lock switching valve 30 is switched to the lock position A. (That is, forced locking is performed) prevents malfunction of the hydraulic motor 16 in this state. On the other hand, when the operation start operation (operation for starting the engine 10 and switching the operation suspension lever 38 to the operation position) is performed in a state where the operation lever 22 is not in the neutral position (NO in step S25), the pump flow rate is reduced to the minimum flow rate. Therefore, the malfunction of the hydraulic motor 16 is prevented.

  In the third embodiment, the forced lock switch 39 is omitted. However, the switch 39 is used to perform a forced lock, that is, a lock when the operation stop lever 38 is switched to the operation stop position. Needless to say, it may be. Thus, if the forced lock switch 39 and the capacity control means are used in combination, even if one of them fails, it is possible to continue proper malfunction prevention control with the other, and the fail-safe function can be enhanced.

It is a circuit diagram which shows the malfunction prevention apparatus of the working machine concerning the 1st Embodiment of this invention. It is a flowchart which shows the control action performed in the said malfunction prevention apparatus. (A) (b) is a time chart which shows the effect | action of the said malfunction prevention apparatus. It is a flowchart which shows the control action performed in the malfunction prevention apparatus concerning the 2nd Embodiment of this invention. (A) (b) is a time chart which shows the effect | action of the malfunction prevention apparatus concerning the said 2nd Embodiment. It is a flowchart which shows the control action performed in the malfunction prevention apparatus concerning the 3rd Embodiment of this invention.

Explanation of symbols

10 Engine 11 Engine oil pressure switch (Engine operation detection means)
12 Main hydraulic pump (variable displacement hydraulic pump)
14 Pilot hydraulic pump (pilot pressure supply source)
16 Hydraulic motor (actuator)
18 Control valve 20 Remote control valve (pilot pressure operating means)
22 Operation lever (operation member)
26A, 26B Pressure switch (Pilot pressure detection means)
30 Lock switching valve 30a Solenoid of lock switching valve 31 Lock operating means 32 Battery (power supply)
36 Operation stop changeover switch 38 Operation stop lever (operation stop change member)
39 Forced lock switch (composes forced locking means)
40 controller (composed of forced locking means)
42 Proportional pressure reducing valve (capacity control means)

Claims (11)

An engine operation detecting means for detecting whether or not the engine is operating in a work machine including a hydraulic pump driven by an engine and an actuator that operates by receiving supply of hydraulic oil from the hydraulic pump; The supply path from the shut-off position, which is interposed between the hydraulic pump and the actuator and shuts off the supply path of hydraulic oil from the hydraulic pump to the actuator by receiving supply of pilot pressure from a pilot pressure supply source. A control valve that is switched to an open position for opening the valve, an operation member for operating the supply of the pilot pressure to the control valve, and a pilot that changes the supply state of the pilot pressure according to the operation position of the operation member Pressure operating means, and the operating position of the operating member causes the control valve to A neutral position detecting means for detecting whether or not the actuator is in the neutral position, an operation pause position for forcibly stopping the operation of the actuator regardless of the operation position of the operation member, and the actuator An operation stop switching member that is switched to an operation position for enabling operation, an operation stop switching detecting means that detects a switching position of the operation stop switching member, and between the control valve and its pilot pressure supply source. A lock switch that is switched between a lock position that interrupts the supply of pilot pressure from the pilot pressure supply source to the control valve and an unlock position that allows the supply of the pilot pressure regardless of the operation position of the operation member. And a lock operation means for performing at least the following operations a to c on the lock switching valve. Malfunction prevention apparatus for a working machine, characterized and.
Operation a. When the operation stop switching member is in the operation stop position, the lock switching valve is set to the lock position.
Operation b. A state where the engine is operating and the operation stop switching member is in the operation position is an operation permission state, and when the operation is in an operation permission state, the lock switching valve is set to the unlock position.
Operation c. Even when in the operation permission state, when it is detected that the operation member is not in the neutral position at the time when the operation start operation for switching from the state that is not the operation permission state to the operation permission state is performed, the lock switching valve To the locked position.   2. The malfunction prevention device for a work machine according to claim 1, wherein the lock operation means detects that the operation member is not in the neutral position until a specific time elapses after the operation start operation is performed. An apparatus for preventing malfunction of a work machine, characterized in that the lock switching valve is set to the lock position when the operation is performed.   2. The malfunction preventing apparatus for a work machine according to claim 1, wherein the neutral position detecting means is a pilot pressure detecting means for detecting whether or not a pilot pressure higher than a specific pressure is supplied to the control valve, and the lock operating means. Switches the lock switching valve to the unlock position when the operation start operation is performed, and specifies the specific value to the control valve until a specific time elapses from the time of switching to the unlock position. A malfunction prevention device for a work machine, wherein the lock switching valve is returned to the lock position when it is detected that a pilot pressure higher than the pressure is supplied.   The malfunction prevention device for a work machine according to any one of claims 1 to 3, wherein the lock operation unit is configured to release a specific lock after the lock switching valve is set to the lock position despite being in the operation-permitted state. An apparatus for preventing malfunction of a work machine, wherein when the operation is performed, the lock switching valve is switched to the unlock position.   5. The malfunction prevention device according to claim 1, wherein the lock switching valve is an electromagnetic switching valve, and the lock operating means includes a power source that supplies an excitation current to a solenoid of the electromagnetic switching valve, and the power source. And the solenoid, and opens and closes in conjunction with the operation of the operation stop switching member so that the lock switching valve is switched to the lock position when the operation stop switching member is in the operation stop position. When it is detected that the operation member is not in the neutral position at the time when the operation start operation is performed, the lock switch valve is set regardless of whether the operation stop switch is open or closed. An apparatus for preventing malfunction of a work machine, comprising force locking means for switching a conduction state between the power source and the solenoid so as to be in a locked position.   An engine operation detecting means for detecting whether or not the engine is operating in a work machine including a hydraulic pump driven by an engine and an actuator that operates by receiving hydraulic oil supplied from the hydraulic pump; The supply path from the shut-off position, which is interposed between the hydraulic pump and the actuator and shuts off the supply path of hydraulic oil from the hydraulic pump to the actuator by receiving supply of pilot pressure from a pilot pressure supply source. A control valve that is switched to an open position for opening the valve, an operation member for operating the supply of the pilot pressure to the control valve, and a pilot that changes the supply state of the pilot pressure according to the operation position of the operation member Pressure operating means, and the operating position of the operating member causes the control valve to A neutral position detecting means for detecting whether or not the actuator is in the neutral position, an operation pause position for forcibly stopping the operation of the actuator regardless of the operation position of the operation member, and the forced pause An operation stop switching member that is switched to an operation position for releasing the operation, an operation stop switching detection means that detects a switching position of the operation stop switching member, and the operation stop switching member when the operation stop switching member is at the operation stop position. Lock means for disabling operation of the actuator by operation of an operation member, flow rate operation means for changing a pump flow rate that is a supply flow rate of hydraulic oil from the hydraulic pump to the control valve, the engine is operated, and the When the operation start operation is performed in which the operation stop switching member is in the operation position, the operation member is moved to the neutral position. It malfunction prevention apparatus for a working machine, characterized in that a flow control means for operating said flow operating means to regulate flow rates up to preset the pump flow rate when it is detected.   7. The work machine malfunction prevention device according to claim 6, wherein the flow rate control means regulates the pump flow rate to a preset flow rate when the operation stop switching member is in the operation stop position. Malfunction prevention device for work machines.   7. The malfunction prevention device for a work machine according to claim 6, wherein the lock means supplies pilot pressure to the control valve regardless of the operation position of the operation member when the operation stop switching member is in the operation stop position. An apparatus for preventing malfunction of a work machine, comprising: a lock switching valve for forcibly shutting off.   The malfunction prevention device for a work machine according to any one of claims 6 to 8, wherein the flow rate control means is configured such that the operation member is in the neutral state until a specific time elapses after the operation start operation is performed. An apparatus for preventing malfunction of a work machine, wherein when it is detected that the pump is not in a position, the flow rate operating means is operated so that the pump flow rate becomes the regulated flow rate.   The malfunction prevention device for a work machine according to any one of claims 6 to 9, wherein the flow rate control means is specified in a state where the pump flow rate is regulated to the regulated flow rate even though the operation is allowed. An apparatus for preventing malfunction of a work machine, wherein the flow rate operation means is operated so that the pump flow rate is switched to the operation flow rate when the restriction release operation is performed.   11. The malfunction prevention device according to claim 6, wherein the hydraulic pump is a variable displacement type, and the flow rate operating means changes a capacity of the hydraulic pump. Malfunction prevention device.

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