JP4925575B2 - Work vehicle safety circuit - Google Patents

Description

  In the traveling vehicle having at least a pair of slide frames that can be expanded and contracted in the vehicle width direction, the operation of the desired actuator is detected when it is detected that the distance between the pair of slide frames is the maximum expansion / contraction state. In particular, in a construction machine having a lower traveling body in which the interval of the crawler belts can be expanded and contracted, the safety circuit that allows the operation of the work machine or the like when the crawler belt interval is in the maximum widened state. It is about.

  Among construction machines equipped with crawler belts such as a crawler crane, a crawler backhoe, a hydraulic excavator, a crane truck, etc., those equipped with an expansion / contraction mechanism capable of changing the crawler belt interval to increase or decrease the vehicle body size are known. When working on a work implement, the crawler belt interval is increased to increase the vehicle body size in order to improve the stability of the vehicle, and when transporting construction machinery or passing through narrow roads, The size of the vehicle body is reduced by shrinking the interval of the crawler belts so that it can be loaded or passed through a narrow road.

  In addition, in crane vehicles, in order to improve the stability and prevent the vehicle from falling when the crane is operating, the outriggers are extended from the body frame side during crane operation to ensure the safety of the vehicle. There is known a mechanism equipped with a mechanism for storing an outrigger in a vehicle body frame side when the crane is not in operation.

  Various configurations have been proposed as a configuration in which the traveling vehicle includes a detection sensor that detects whether the interval between the crawler belts is widened or the outriggers are overhanging. Among these, a crawler belt expansion / contraction detection device that detects a crawler belt interval, selects a rated load curve corresponding to the crawler belt interval, and performs work of the work implement based on the selected rated load curve (see Patent Document 1). Has been proposed.

  The enlargement / reduction detection apparatus described in Patent Document 1 has a configuration shown in FIGS. FIG. 7 shows a plan view of the lower traveling body 140 in the crawler crane, and FIG. 8 shows a main part of the detection device on one side of the crawler belt when the interval between the crawler belts 122 is widened.

  As shown in FIG. 7, the lower traveling body 140 includes a track frame 120 and a pair of side frames 121. A pair of connecting portions 120a are formed on both sides of the track frame 120 so as to project outward. A pair of left and right side frames 121 are connected to the connecting portion 120a.

  Drive wheels 135 and driven wheels 136 that are rotationally driven by a hydraulic drive device 124 are respectively provided at the front and rear portions of each side frame 121. A widening cylinder 123 is provided between the left and right side frames 121 and the track frame 120. The piston rod side of the widening cylinder 123 is connected to one of the left and right side frames 121, and the cylinder part side is connected to the other side frame 121.

  By expanding and contracting the widening cylinder 123, each side frame 121 is guided by the connecting portion 120a, and the working position (position where the distance between the crawler belts 122 is widened) and the transporting position (the distance between the crawler belts 122) with respect to the track frame 120. It is possible to move between (reduced position).

  In a state where the side frame 121 is contracted with respect to the track frame 120, the switching valve 125 of the three switching valves 125 to 127 disposed on the lower traveling body side comes into contact with the protruding portion 121b formed on the side frame 121. The position of the switching valve 125 is switched. At this time, the pressure oil discharged from the hydraulic drive device 124 is not supplied from the switching valves 126 and 127 to the pressure detectors 130 and 131, and only the pressure oil passing through the switching valve 125 passes through the hydraulic rotary joint 128. A pressure detector 129 is supplied.

  Of the switching valves 125 to 127, only the switching valve switched by the protrusion 121b can communicate between the hydraulic drive device 124 and the pressure detectors 129 to 131. The widening position of the side frame 121 can be detected by detection signals from the pressure detectors 129 to 131 communicating with the pressure source 124.

  The controller 132 detects the output state where the pressure detection signals are output from the pressure detectors 129 to 131 as “1”, and the output state where the pressure detection signal is not output as “0”. The state shown in FIG. 8 shows a state in which the switching valve 125 is switched by the protruding portion 121b. The controller 132 is in a state where the pressure detector 129 is “1” and the pressure detectors 130 and 131 are “0”. ”Is detected.

  The signal input to the controller 132 is “1-0-0”, and the controller 132 detects that the interval between the crawler belts 122 is in the contracted state. The controller 132 determines the detection signal “1-0-0” and outputs an instruction signal to the moment limiter 133 based on the detection signal. The moment limiter 133 selects a desired rated load curve from a plurality of rated load curves stored in the memory based on an instruction from the controller 132, and prevents an overload of the crane based on the rated load curve. Yes.

Similarly, when the switching valve 126 comes into contact with the protruding portion 121b, the controller 132 inputs a signal “0-1-0”, and when the switching valve 127 comes into contact with the protruding portion 121b, the controller 132 reads “0-0”. -1 "signal is input. The controller 132 outputs an instruction signal based on the input signal to the moment limiter 133, and the moment limiter 133 performs control on the crane based on the rated load curve selected based on the instruction signal.
JP-A-10-53169

  In the crawler belt expansion / contraction detection device described in Patent Literature 1, when the interval between the crawler belts 122 is in the reduced position, in the intermediate position, or in the widened position, the load rating curve for controlling the crane in each case is divided. Seeking. The crane is controlled based on the obtained rated load curve.

  However, in order to detect the expansion / contraction state of the pair of side frames 121, the switching valves 125 to 127 have to be provided for each side frame 121. For this reason, an installation place for providing the switching valves 125 to 127 has to be secured in the sliding portion of each side frame 121.

  In order to detect the widening position of the side frame 121 using the switching valves 125 to 127, the number of pipes connected to the switching valve must be increased as the number of switching valves increases, and piping is performed. We needed a lot of space.

  Further, although the crawler belt interval is detected in three stages, the rated load for operating the crane at each stage is obtained, and the crane is controlled by the obtained rated load. For this reason, when the crawler belt interval is equal to or less than the maximum widening interval originally necessary for safe work, safety measures such as the operation of the work machine and the turning motion of the upper revolving structure are taken. It wasn't.

  Furthermore, when the protrusion 121b exists between the switching valves, there is a problem in that it is impossible to confirm from the driver's seat which distance is currently the crawler belt interval.

  In the present invention, in the traveling vehicle having at least a pair of slide frames that can be expanded and contracted in the vehicle width direction in order to solve the above-mentioned problems, the maximum expansion state of the widening cylinder that widens the interval between the slide frames by one detection means is achieved. An object of the present invention is to provide a safety circuit that detects and disables the operation of an actuator such as a desired work machine when the maximum expanded state is not detected.

The lower traveling body, the upper swing body that is pivotably mounted on the lower traveling body via a swiveling device, the working machine, and the center frame of the lower traveling body as defined in claim 1 In a safety circuit of a work vehicle having a widening cylinder for expanding and contracting a pair of slide frames, an input port of a single switching valve for detecting a maximum expansion state of the widening cylinder, and disposed in the upper swing body The pilot pressure supply pump is connected via a hydraulic rotary joint disposed in the swivel device, and the pilot pressure for operating the actuator is supplied to at least one operating means for operating a desired actuator. A pilot control valve for connecting / disconnecting the first pilot line is provided in one pilot line, and the output port of the switching valve is connected / disconnected to / from the input port. And a pilot pilot valve of the pilot control valve are connected by a second pilot line via the hydraulic rotary joint, and connected to and disconnected from a pilot pressure controlled by a signal from a release switch and supplied to the hydraulic pilot part A second pilot control valve for performing the control is provided, the output line from the second pilot control valve and the second pilot line are joined via a shuttle valve, and the output pressure from the shuttle valve is controlled by the pilot control. The pilot portion of the valve is supplied, and the pilot pressure from the switching valve or the pilot pressure from the second pilot control valve is introduced into the pilot portion of the pilot control valve, thereby connecting the first pilot line The most important feature is to switch to the state.

Further, as described in claim 2, the main feature is that the indicator lamp is turned on when the second pressure detector detects the operation of the switching valve, and the alarm buzzer is operated during the operation of the release switch. ing.

  In the present invention, at least one pair of slide frames is slidably expanded and contracted with respect to the vehicle body frame by one widening cylinder. In addition, the maximum expansion state of the widening cylinder is detected by a single switching valve, and when the maximum expansion state of the widening cylinder is detected by the switching valve, pilot pressure is supplied to the operating means for operating a desired actuator. Operation is allowed.

  Further, when the switching valve has not detected the maximum expansion state of the widening cylinder, the operation of the operation means is invalidated by shutting off the supply of pilot pressure to the operation means for operating the desired actuator.

  That is, for example, when the pair of slide frames are outriggers, when the outriggers are not expanded, the operation of the operating means can be disabled so that the work implement cannot be operated by the operation of the switching valve. . Only when the outrigger is in the maximum expanded state, the operation means is enabled so that the work implement can be operated by the switching valve.

  Further, for example, when at least a pair of slide frames are expanded and contracted with respect to the vehicle body frame along with the expansion and contraction of the side frames on the left and right sides of the vehicle, the changeover valve detects that the distance between the side frames is the maximum expansion interval. Can do. This prevents, for example, the operation of the work implement and the turning operation of the upper turning body until the interval between the crawler belts provided in the side frame reaches the maximum widening interval, that is, until the switching valve is activated. And the safety of the vehicle can be ensured.

  The maximum expansion state of the widening cylinder by a single switching valve is, for example, that a long operating member is attached to a piston rod, and a receiving member and a switching valve are disposed on the long operating member and the cylinder of the widening cylinder, respectively. It can be configured. By bringing the switching valve and the receiving member into contact with each other in the maximum expanded state of the widening cylinder, the switching valve can be operated to detect the maximum expanded state of the widening cylinder.

  Since the switching valve is used to detect the maximum expansion state of the widening cylinder, the operating state of the switching valve disposed in the lower traveling body can be swung with respect to the lower traveling body using an existing hydraulic rotary joint. It can be detected in a simple upper swing body. For this reason, it is possible to detect the switching valve and the upper swing body by using a hydraulic rotary joint without using a special rotary joint as in the case where an electrical signal is used to detect the widened state of a pair of slide frames. Can be connected to each other.

  In addition, it is possible to reduce the space required for the installation site of the widening cylinder and the installation site of the switching valve, and the piping of the connection pipe line to the switching valve can also be a simple arrangement.

As a circuit configuration for controlling the pilot control valve by the operation of the switching valve, a circuit configuration for controlling the pilot control valve by directly introducing the pressure from the switching valve into the hydraulic pilot part of the pilot control valve can be adopted.

By controlling the pilot control valve by the operation of the switching valve, the pilot pressure can be supplied to the operating means for operating the actuator such as a work machine in the maximum expanded state of the widening cylinder in which the switching valve is operated. . That is, the first pilot pipe line can be made conductive.

When the switching valve is not actuated, that is, when the widening cylinder is not in the maximum widening state, the first pilot line is shut off. Thereby, the operation of the operation means for operating the actuator can be invalidated.

  Even when the movable frame is an outrigger, or when the widening cylinder is in the maximum expanded state, even if the movable frame moves in the expansion / contraction direction integrally with the side frame that expands / contracts the crawler belt interval. Assuming that the stability of the vehicle is ensured, the operation of the work machine and the turning operation of the upper-part turning body can be performed by the operation of the switching valve.

  When the widening cylinder is not in the maximum expanded state, if the work machine or the like is operated in this state or if the upper-part turning body is turned, the operation of the actuator can be invalidated because the vehicle may fall over. . Thereby, the safety | security with respect to a vehicle can be improved.

In addition, even when the widening cylinder is not in the maximum expanded state and the switching valve is not operating, the operation of the operating means of the actuator that has been disabled is enabled by operating the release switch. Can be made. At this time, in order to warn an operator or the like that the release switch is operating, it is necessary to sound an alarm buzzer while the release switch is operating. In addition to the alarm buzzer, it is also possible to cause a warning by turning on a lamp or the like or flashing it together with an alarm sound of the alarm buzzer.

  While the switching valve is in operation, the operator can be informed that the widening cylinder is in the maximum expanded state by turning on the indicator lamp. When the indicator lamp is turned off, the operator understands that the widening cylinder is not in the maximum expanded state. For this reason, when operating an actuator whose operation has been disabled while the display lamp is off, the disabled actuator can be operated by operating a release switch.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The configuration of the lower traveling body according to the present invention will be described below by using a configuration in which the interval between the crawler belts can be expanded and reduced by taking a hydraulic excavator as an example. The present invention is not limited to the slide frame that moves in the expansion / contraction direction together with the side frame, and can be suitably applied to the case where the slide frame is used as an outrigger.

  In addition to the hydraulic excavator described below, the present invention can be applied to any traveling vehicle that can solve the problems of the present invention. For this reason, this invention is not limited to the Example demonstrated below, A various change is possible.

  FIG. 1 is a side view showing a hydraulic excavator according to an embodiment of the present invention. On the lower traveling body 2, an upper swing body 3 including a work machine 4 is mounted via a swing device 5 so as to be able to swing. As shown in a plan view of the lower traveling body 2 in FIG. 2, side frames 8 are attached to the center frame 7 as a body frame on the left and right. A drive wheel 13 and a driven wheel 14 that are rotationally driven by a drive motor 12 are disposed on the side frame 8, and a crawler belt 6 is wound between the drive wheel 13 and the driven wheel 14.

  As shown in FIG. 2 in which the widening cylinder 20 is extended and the side frame 8 is widened, the center frame 7 has two pairs of slide frames 9 arranged in the front-rear direction of the vehicle. It is installed. The slide frames 9 arranged at the front and rear are respectively attached to the side frames 8, and are arranged so as to be slidable in the lateral direction of the vehicle as the side frames 8 expand and contract. A receiving seat 16 is formed at the center of the center frame 7. A swivel device 5 shown in FIG. 1 is provided.

  An expansion / contraction cylinder 20 is disposed between the pair of side frames 8, and end portions of the piston rod 21 and the cylinder portion 22 of the expansion / contraction cylinder 20 are supported by flange portions 17 a and 17 b fixed to the side frames 8. .

  Each side frame 8 is provided with a stopper rod 15, and the maximum width of each side frame 8 is increased by contact between a contact plate 15 a provided on the center frame 7 and a flange portion formed at the end of the stopper rod 15. Is regulated. The maximum width of each side frame 8 can be adjusted by adjusting the screwing positions of the pair of fixing nuts 18 screwed to the other end of the stopper rod 15.

  In the state in which the side frames 8 are widened, the end portions of the stopper rods 15 disposed on the side frames 8 are in contact with the contact plate 15a of the center frame 7, and the distance between the pair of side frames 9 is the maximum widening. It is in a state.

  3 and 4 are diagrams illustrating the operation of the switching valve 25 that detects the widened state of the widening cylinder 20. A switching valve 25 is fixed to the cylinder portion 22 of the widening cylinder 20 by fixing means 27 made of a U-shaped band or the like.

  A long operating member 23 is disposed on one end side of the piston rod 21, and the long operating member 23 moves in the longitudinal direction of the piston rod 21 integrally with the expansion and contraction of the piston rod 21. Can do. A flange portion 28 is disposed at one end of the elongated operating member 23, and a receiving member 26 that contacts the switching valve 25 and switches the switching position of the switching valve 25 is disposed in the flange portion 28.

  The receiving member 26 includes an operating piece 26a that contacts the switching valve 25 and switches the switching position of the switching valve 25. The operating piece 26a is urged in the direction of the switching valve 25 by a spring 26b interposed between the receiving member 26 and the flange portion 28. Has been.

  The long operating member 23 is configured by a hollow member having a slit formed in the longitudinal direction. The guide piece 29 provided in the switching valve 25 is inserted through the slit and slidably contacts the inner surface of the elongated operating member 23, and the switching valve 25 and the elongated operating member with respect to the longitudinal direction of the elongated operating member 23. 23 is allowed to slide, and the relative rotation between the switching valve 25 and the elongated operating member 23 is prevented.

  By extending the widening cylinder 20, the cylinder portion 22 moves upward in FIG. 3, and the piston rod 21 moves downward in FIG. As a result, when the widening cylinder 20 is in the contracted state, the switching valve 25 and the receiving member 26 that were in the position of the solid line move as indicated by the alternate long and short dash line and come into contact with each other.

  A contact rod 25 d that moves the spool of the switching valve 25 protrudes from the switching valve 25. At the time of movement of the contact rod 25d and contact of the receiving member 26 with the operating piece 26a, a spring (spring 25e in FIG. 5) biasing the contact rod 25d and a spring 26b biasing the operating piece 26a. Thus, the impact at the time of contact is absorbed.

  Further, the switching of the switching valve 25 is maintained by the displacement of the contact rod 25d and the displacement of the operating piece 26a by the displacement of the springs 25e and 26b. For this reason, even if the side frame 8 is slightly displaced during the work of the work machine or the like by the amount of compression of each spring 25e and spring 26b, it can be continuously detected that the crawler belt interval is in the maximum widened state. It is possible to continue working with the machine.

  When the switching valve 25 and the receiving member 26 come into contact with each other and the switching valve is operated, the widening cylinder 20 is expanded to the maximum, that is, the side frame 8 is in the maximum widening state as shown in FIG. Can be detected. The operation of the safety circuit detected by the switching valve 25 that the side frame 8 has reached the maximum widened state will be described in the first embodiment below with reference to the circuit diagram of FIG.

  In FIG. 5, the pilot circuit from the first hydraulic pump 42 that discharges the pilot pressure, the operation circuit of the second hydraulic pump actuator supply pump 43 that discharges the pressure oil that operates the actuator, and the change of the switching position of the switching valve 25. The first signal circuit from the pressure detector 44 for detecting the signal and the second signal circuit from the release switch 45 that can temporarily release the state in which the actuator cannot be operated by the signal from the pressure detector 44. It consists of and.

  In FIG. 5, the pipeline indicated by the dotted line is formed as a drain pipeline. Further, in FIG. 5, the structures of the widening cylinder 20, the switching valve 25, and the receiving member 26 are shown together for easy explanation.

  The switching valve 25, the actuators 40A and 40B disposed in the lower traveling body, and the first hydraulic pump 42, the second hydraulic pump, and the like provided in the upper swinging body are connected to a rotary connecting portion between the lower traveling body and the upper swinging body. Therefore, the hydraulic rotary joint 30 is provided in the turning device 5 shown in FIG. In the present invention, the switching valve 25 is used to detect that the widening cylinder 20 is in the maximum expanded state, and there is an advantage that a conventionally known hydraulic rotary joint can be used as it is.

  Next, starting with the pilot circuit, the related circuits will be described in sequence with reference to FIG. The pilot circuit can flow the pilot pressure oil that is sucked and discharged from the tank 48 by the first hydraulic pump 42. The pilot pressure oil discharged from the first hydraulic pump 42 is supplied to the first control valve 31 through the conduit 50. The first control valve 31 is switched by an external control signal to connect / disconnect the conduit 50 and the conduit 51.

  The pressure oil in the pipe 51 is branched and connected to the third port 25 c of the switching valve 25 via the pipe 52 and the hydraulic rotary joint 30. The switching valve 25 is configured as a switching valve having two positions (I, II) and three ports 25a to 25c. The port 25 a is connected to the pipe 55 via the pipe 54 and the hydraulic rotary joint 30, and the pipe 55 is connected to the pressure detector 44. The port 25b is formed as a drain port.

When the widening cylinder 20 expands and the receiving member 26 and the switching valve 25 come into contact with each other, the contact rod 25d of the switching valve 25 compresses the spring 25e by the operating piece 26a (see FIG. 4) of the receiving member 26. Move to the right in FIG . Thereby, the switching valve 25 is switched from the switching position (II) to the switching position (I).

  When the switching valve 25 and the receiving member 26 are not in contact, the switching valve 25 maintains the switching position (II) by the biasing force of the spring 25e. When the switching valve 25 is switched to the switching position (I), the pipe line 53 and the pipe line 55 communicate with each other, and the pressure detector 44 can detect the pilot pressure.

  The pressure oil in the pipe line 51 connected to the first control valve 31 is distributed by the P block 36, and a part thereof is supplied to the third operating means through the pipe line 58. The pressure oil in the pilot pilot line 59 connected to the P block 36 is supplied to one supply port of the pilot control valve 32. The pilot control valve 32 is operated by a control signal from the pressure detector 44 via the signal line 80 b or a release signal via the signal line 81 from the release switch 45.

When the pressure detector 44 detects the pilot pressure from the switching valve 25, that is, when the widening cylinder 20 is expanded and the switching valve 25 contacts the receiving member 26, the pressure detector 44 sends a control signal to the signal line 80. The solenoid 32a of the pilot control valve 32 is excited to switch from the switching position (III) in FIG. 5 to the switching position (IV). At the same time, the control signal output from the pressure detector 44 lights the display lamp 49 via the signal line 82. By confirming the lighting state of the display lamp 49, the operator can confirm that the widening cylinder 20 is in the maximum widening state.

  When the control signal is not output from the pressure detector 44, that is, when the widening cylinder 20 where the switching valve 25 and the receiving member 26 are not in contact is not in the maximum expanded state, the pilot control valve 32 is attached with a spring. The switching position (III) is maintained by the force.

  At this time, when the release switch 45 is operated, the solenoid 32a of the pilot control valve 32 can be excited by the release signal from the release switch 45 to switch from the switching position (III) in FIG. 5 to the switching position (IV). . While the release switch 45 is in operation, a release signal can be input to the alarm buzzer 46 to generate an alarm sound. While the alarm sound is generated, it is possible to warn an operator or the like that the release switch 45 is operating.

  When the pilot control valve 32 is switched to the switching position (IV), the pilot pipeline 59 and the pipeline 61 communicate with each other, and the first operating means 37, the second pipeline via the pipelines 62 a and 62 b branched from the pipeline 61. Pilot pressure can be supplied to the operating means 38.

  Thereby, by operating the first operating means 37 and the second operating means 38, the pilot pressure is supplied from the pipe lines 71 to 74 to the actuator (not shown) operated by the first operating means 37 and the second operating means 38. The actuator can be operated by outputting.

  Thus, when the pilot control valve 32 is in the switching position (III), pilot pressure cannot be supplied to the first operating means 37 and the second operating means 38, and the first operating means 37 and second The operation on the actuator by the operation means 38 can be invalidated.

That is, when the switching valve 25 is not switched to the switching position (I) , that is, when the side frame is not at the maximum widening width and the interval between the crawler belts is not widened to be able to perform the work, the first Even if the operation means 37 and the second operation means 38 are operated, the operation of the actuator of the work implement, the actuator for performing the turning operation of the upper-part turning body, and the like can be prevented by the same operation.

  Even when the switching valve 25 is in the switching position (II), the actuator can be operated by operating the first operating means 37 and the second operating means 38 by operating the release switch 45. However, in this case, the alarm buzzer 46 is always operated during the operation of the release switch 45 because the actuator is operated as an emergency measure.

  Accordingly, it can be determined whether or not the crawler belt interval is in the maximum widening state. When the crawler belt interval is not the maximum widening interval, the operation for the desired actuator is invalidated. Can do.

  The second operating means 39 is an operating means for activating the actuators 40A and 40B regardless of whether or not the crawler belt interval is in the widened width state. From the pipe line 51 through the P box 36, the second operation means 39 is operated. The third control valve 34 can be controlled by receiving the pilot pressure.

  The third control valve 34 can switch and supply the discharge pressure from the actuator supply pump 43 for operating the actuator to the pipelines 66 and 67. The pipelines 66 and 67 are connected to the fourth control valve 35 via the hydraulic rotary joint 30. The fourth control valve 35 is switch-controlled by a pilot signal from the second control valve 33 that is operated by a signal from the changeover switch 47. The pilot pressure from the pipe 52 is used as the pilot pressure from the second control valve 33.

  In the present invention, it can be detected by the single switching valve 25 that the crawler belt interval is the maximum widening interval, and when the crawler belt interval is not the maximum widening interval, the operation of the work machine or the like cannot be performed. Can be kept. Furthermore, even when the interval between the crawler belts is the minimum interval, if it becomes necessary to operate the work implement etc., the release switch 45 can be operated to operate the work implement etc. it can.

  While the release switch 45 is in operation, the alarm buzzer can be operated to confirm that the release switch 45 is operated and the work implement is being operated. Thereby, the safety | security with respect to a traveling vehicle can be improved.

  FIG. 6 shows a circuit configuration according to another embodiment of the present invention. The circuit configuration in the first embodiment is different in the following circuit configuration, and the other configurations are the same as those in the first embodiment. It has become. In the second embodiment, the operation of the switching valve 25 is directly introduced into the hydraulic pilot portion 84 of the pilot control valve 32, the second pilot control valve 85 is controlled by the operation of the release switch 45, and the pilot pressure is controlled by the pilot control valve 32. The circuit configuration is such that the hydraulic pilot unit 84 is introduced.

  In the first embodiment, a diode is used so that the control signal from the pressure detector 44 and the release signal from the release switch 45 are not activated by the signal from the other, respectively, and the display lamp 49 and the alarm buzzer 46 are not activated. ing. In contrast, in the second embodiment, since the pilot control valve 32 is operated by the pilot pressure, the pilot pressure from the switching valve 25 introduced into the hydraulic pilot portion 84 of the pilot control valve 32 and the second pilot control valve The pilot pressure from 85 has a circuit configuration in which one pilot pressure is selected and introduced by a shuttle valve 86 disposed on the upstream side of the hydraulic pilot portion 84.

  Also in the second embodiment, in order to turn on the display lamp 49, the second pressure detector 88 for turning on the display lamp 49 is provided in a pipe branched from the second pilot pipe 55. The pipe line 55 in the first embodiment is referred to as a second pilot pipe line 55 'in the second embodiment, and the pilot pipe line 59 is referred to as a first pilot pipe line 59'.

  In the following, the description will be focused on the circuit configuration different from that of the first embodiment, and the description of other circuit configurations and operations thereof will be omitted by using the same member codes as those used in the first embodiment. Shall.

  The port 25a, which is an output port of the switching valve 25, passes through the second pilot pipe line 55 ′ via the rotary hydraulic joint 30 and passes through the shuttle valve 86 disposed in the second pilot pipe line 55 ′ to perform pilot control. It is connected to the hydraulic pilot part 84 of the valve 32. The shuttle valve 86 is connected to the output port of the second pilot control valve 85 that is controlled by the operation of the release switch 45.

  Of the pilot pressure from the switching valve 25 and the pilot pressure from the second pilot control valve 85, the pilot pressure that is output is introduced into the hydraulic pilot portion 84 by the shuttle valve 86.

  The pilot pressure from the pilot pressure supply pump 42 is introduced into the input port of the second pilot control valve 85. When the release switch 45 is operated to control the second pilot control valve 85, the alarm buzzer 46 is activated by a signal from the release switch.

  When the pilot pressure is introduced from the switching valve 25 to the hydraulic pilot part 84, the second pressure detector 88 that is branched from the second pilot line 55 ′ is activated to light the display lamp 49. It has a circuit configuration.

  Thus, in the present invention, it can be detected by the single switching valve 25 that the crawler belt interval is the maximum widening interval, and when the crawler belt interval is not the maximum widening interval, the operation of the work machine or the like is performed. Can not be done. Furthermore, even when the interval between the crawler belts is the minimum interval, if it becomes necessary to operate the work implement etc., the release switch 45 can be operated to operate the work implement etc. it can.

  While the release switch 45 is in operation, the alarm buzzer can be operated to confirm that the release switch 45 is operated and the work implement is being operated. Thereby, the safety | security with respect to a traveling vehicle can be improved. Further, when the switching valve 25 is actuated, the display lamp 49 is lit, so that it can be confirmed that the widening cylinder 20 is in the maximum expanded state.

  The present invention can apply the technical idea of the present invention to an apparatus or the like to which the technical idea of the present invention can be applied.

1 is a side view showing a hydraulic excavator according to an embodiment of the present invention. (Example) It is a principal part top view of the lower traveling body in the state where the side frame was expanded. (Example) It is a principal part side view which shows a wide cylinder and a switching valve. (Example) It is a principal part bottom view including the partially broken surface which shows a wide cylinder and a switching valve. (Example) It is a hydraulic circuit diagram. Example 1 It is a hydraulic circuit diagram. (Example 2) It is a principal part top view of a lower traveling body. (Conventional example) It is a figure which shows the structure of a widening detection apparatus. (Conventional example)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic excavator 2 Lower traveling body 3 Upper revolving body 6 Crawler belt 7 Center frame 8 Side frame 9 Slide frame 20 Widening cylinder 21 Piston rod 22 Cylinder part 23 Long operating member 25 Switching valve 26 Receiving part 30 Hydraulic rotary joint 32 Pilot control Valve 37 First operation means 38 Second operation means 39 Third operation means 42 Pilot pressure supply pump 44 Pressure detector 45 Release switch 46 Alarm buzzer 49 Display lamps 50 to 55 Line 55 'Second pilot lines 57 to 61 Pipe Path 59 ′ first pilot line 85 second pilot control valve 88 second pressure detector 120 track frame 121 side frame 122 crawler belt 123 expansion / contraction cylinder 124 hydraulic drive devices 125 to 127 switching valve 128 hydraulic rotary joints 129 to 131 pressure detector 132 Controller 13 3 Moment limiter 140 Lower traveling body

Claims (2)

A lower traveling body, an upper revolving body that is rotatably mounted on the lower traveling body via a swivel device, a work machine, and at least a pair of slide frames are slidably expanded and contracted with respect to the center frame of the lower traveling body. In a safety circuit for a work vehicle equipped with a widening cylinder,
An input port of a single switching valve that detects the maximum expansion state of the widening cylinder and a pilot pressure supply pump disposed in the upper swing body are connected via a hydraulic rotary joint disposed in the swing device. ,
A pilot control valve for connecting and disconnecting the first pilot pipe is disposed in a first pilot pipe that supplies pilot pressure for operating the actuator with respect to at least one operating means that operates a desired actuator.
An output port of the switching valve that is connected to and disconnected from the input port, and a hydraulic pilot portion of the pilot control valve are connected by a second pilot line via the hydraulic rotary joint;
A second pilot control valve that is controlled by a signal from a release switch and that connects and disconnects the pilot pressure supplied to the hydraulic pilot section;
An output line from the second pilot control valve and the second pilot line are joined via a shuttle valve, and an output pressure from the shuttle valve is supplied to a pilot section of the pilot control valve;
A pilot pressure from the switching valve or a pilot pressure from the second pilot control valve is introduced into a pilot portion of the pilot control valve to switch the first pilot pipeline to a connected state. Safety circuit for work vehicles. A second pressure detector is disposed between the hydraulic rotary joint and the shuttle valve in the second pilot line, an indicator lamp is turned on by an output signal from the second pressure detector, and the release switch the output signal, the safety circuit of the working vehicle according to claim 1, characterized in that to operate the warning buzzer.

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