JP4991132B2 - Work vehicle safety device - Google Patents

Description

  The present invention relates to a safety device for a work vehicle configured with a boom on a traveling body, and more specifically, the grounding state of a jack protruding before the start of work has not been sufficiently confirmed, so The present invention relates to a safety device for a work vehicle having a configuration capable of preventing a situation that may be stabilized.

  Examples of work vehicles configured with a boom on a traveling body include an aerial work vehicle having a work platform for operator boarding at the tip of the boom, and a crane vehicle having a suspension device at the tip of the boom. Etc. are known. Jacks (outrigger jacks) are provided at various places on the traveling body of such a work vehicle, and before the work, these jacks are projected downward to be grounded so that the traveling body is supported in a stable state. . As a result, the traveling body can resist a large overturning moment acting on the traveling body during work involving the operation of the boom, and the work can be safely performed without causing the traveling body to fall.

In such a work vehicle, an interlock circuit is provided so that the boom cannot be operated unless the jack is extended to the grounded state, and the jack cannot be operated in a state where the boom can be operated. Many are provided (see, for example, the following patent document). According to such an interlock circuit, the operation of the boom is performed with the jack ungrounded, so that the traveling body may overturn or the jack is accidentally stored during work involving the operation of the boom. It is possible to prevent a situation in which the posture of the traveling body becomes unstable due to the accident, so that the safety of work can be improved.
JP 2003-128393 A

  However, even if the work vehicle is equipped with an interlock circuit as described above, the safety of the work will be improved unless the overhanging jack is in contact with the ground in a state where it can stably support the traveling body under work. It cannot be certain. For example, if the jack is surely grounded but the ground is actually loose, or if the grounding plate of some jacks is caught on the edge of the side groove, the traveling body tilted during work The load cannot be sufficiently supported, and the traveling body may become unstable.

  The present invention has been made in view of such a problem, and since the ground contact state of the jack protruding before the start of work has not been sufficiently confirmed, a situation in which the traveling body is made unstable after the start of work is obtained. An object of the present invention is to provide a work vehicle safety device that can be prevented from occurring.

A safety device for a work vehicle according to the present invention is provided at a traveling body, a boom that is provided on the traveling body, and has a working device (for example, the work table 40 in the embodiment) at a distal end thereof, and is provided at a plurality of locations on the traveling body. A jack that supports the traveling body in a grounding state projecting downward, a boom operating means for operating the boom (for example, a boom operating lever 51 in the embodiment), and operating the boom according to the operation of the boom operating means. The boom operation control means (for example, the controller 60 in the embodiment) and at least one jack among a plurality of jacks are provided so as to be operable at a position where the ground contact state can be visually confirmed. ground state confirmation means for urging (e.g., ground state confirmation switch 71 in the embodiment) and, that all of the plurality of jacks becomes grounded state test And the ground state detecting means (for example, the jack ground completion switch 82 in the embodiment), after all of the plurality of jacks is detected to have become the ground state by the ground state detecting means, the operation of the ground state confirmation means lines And an interlock circuit that enables operation of the boom by the boom operation control means.

  In addition, the work vehicle safety device has jack operating means (for example, the jack operating lever 53 in the embodiment) for performing a jack extension operation on the traveling body, and the grounding state checking means is provided with the jack operating means. It is preferable to be provided in the vicinity of the jack where the ground contact state cannot be directly seen from the existing position.

  In the work vehicle safety device according to the present invention, the boom cannot be operated unless the operation of the ground contact state confirmation means is performed after the operation of extending the jack. After the operation, the grounding state of at least one jack is visually confirmed before the grounding state confirmation means is operated. At the time of this visual check, the worker will carefully check the ground condition etc. of the place where the work is going to be done and carefully judge whether it is a suitable place for the work. Since the jack cannot support the traveling body after the start, the traveling body does not become an unstable posture, and the safety of work can be improved more than before.

  In addition, if the grounding state confirmation means is provided at a position near the jack where the grounding state cannot be directly seen from the position where the jack operation means is provided, the operator directly looks at the grounding state. As a result, it is necessary to move to a position near the jack where it is not possible to perform a visual check of the grounding state of all jacks. For example, when some jacks are caught on the edge of the side groove Even so, it becomes possible for the operator to find this before work, and it is possible to further improve the safety of the work.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows an aerial work vehicle 1 equipped with a work vehicle safety device according to an embodiment of the present invention. The aerial work vehicle 1 includes a truck-type traveling body 10 that includes traveling wheels 11,... That can be traveled from a driving cabin 12, a swivel base 20 provided on the traveling body 10, A boom (expandable boom) 30 having a base end supported on an upper portion of a support column 21 extending upward from the swivel base 20 via a foot pin 22, and an operator boarding attached to the distal end of the boom 30. The work table 40 is configured.

  The swivel base 20 is attached to the rear part of the traveling body 10 so as to be rotatable 360 degrees around the vertical axis. A swing motor (hydraulic motor) 23 (see FIG. 1) is provided inside the traveling body 10, and the swivel motor 20 is rotated to move the swivel base 20 through a gear (not shown). be able to. The boom 30 has a base boom 30a, an intermediate boom 30b, and a distal boom 30c that are nested, and each boom 30a, 30b is operated by a telescopic operation of a telescopic cylinder (hydraulic cylinder) 31 (see FIG. 1) provided therein. , 30c can be moved relatively to expand and contract the entire boom 30 in the axial direction. Further, a hoisting cylinder (hydraulic cylinder) 24 is straddled between the base end boom 30a and the column 21 of the swivel base 20, and the hoisting cylinder 24 is caused to move up and down by extending and retracting the hoisting cylinder 24. Can do.

  A vertical post holding bracket 32 is attached to the tip of the tip boom 30c, and the lower end of the vertical post 33 is pivotally supported by the vertical post holding bracket 32. The vertical post 33 is configured so that a vertical posture is always maintained by a leveling actuator (not shown) regardless of the undulation angle of the boom 30.

  The work table 40 has a box shape, and is rotatably attached to the upper end portion of the vertical post 33 via a work table holding bracket 41 that protrudes to the outside. A swing motor (hydraulic motor) 42 (see FIG. 1) is provided inside the work table holding bracket 41. By rotating the swing motor 42, the entire work table 40 is moved around the vertical post 33. It can be swung (horizontal turning). Here, since the vertical post 33 is always maintained in the vertical posture as described above, as a result, the floor surface of the work table 40 is always held horizontally regardless of the undulation angle of the boom 30.

  The work table 40 is provided with an upper operation device 43, in which a movement operation of the work table 40, that is, a boom operation lever 51 for performing the turning, raising and lowering operations of the boom 30, and the neck of the work table 40. A worktable operation lever 52 for performing a swing operation is provided (see FIG. 1). An operator who has boarded the work table 40 operates the boom operation lever 51 and the work table operation lever 52 to rotate the swing motor 23, extend and retract the hoisting cylinder 24, extend and retract the telescopic cylinder 31, and swing. Each operation of the rotation operation of the motor 42 can be performed. Here, the boom operation lever 51 can be twisted around the axis in addition to the tilting operation in the front-rear direction and the left-right direction. The boom operation lever 51 can be twisted around the axis of the boom 30 (the swivel base 20). And the boom operation lever 51 tilting operation in the front-rear direction corresponds to the hoisting operation of the boom 30 (the telescopic operation operation of the hoisting cylinder 24). The left / right tilting operation corresponds to the expansion / contraction operation of the boom 30 (the expansion / contraction operation of the expansion / contraction cylinder 31). Further, the work table operation lever 52 can be tilted in the left-right direction, and the tilt operation in the left-right direction of the work table operation lever 52 is a swing operation of the work table 40 (rotation operation operation of the swing motor 42). It corresponds to.

  As shown in FIG. 1, the swing motor 23 is connected to the swing motor 42 via the swing motor operation valve 23v, the lift cylinder 24 is connected via the lift cylinder operation valve 24v, and the telescopic cylinder 31 is connected via the extend cylinder control valve 31v. Is supplied with pressure oil discharged from a hydraulic pump P provided in the traveling body 10 via a swing motor operation valve 42v. These valves 23v, 24v, 31v, 42v are all electromagnetic proportional directional flow control valves, and the swing motor 23, the undulation cylinder 24, the telescopic cylinder 31, and the swing motor 42 correspond to the valves 23v, 24v, 31v, respectively. , 42v are operated at directions and speeds according to the driving state of each spool (not shown).

  The controller 60 provided in the traveling body 10 includes a swing motor operation valve 23v and a hoisting cylinder based on operation signals output by operating the boom operation lever 51 in each direction (axial direction, front-rear direction, and left-right direction). The spools of the operation valve 24v and the telescopic cylinder operation valve 31v are driven, and the spool of the swing motor operation valve 42v is driven based on the operation signal output by the operation of the worktable operation lever 52 (see FIG. 1).

  With such a configuration, an operator who has boarded the work table 40 operates the boom operation lever 51 to turn, raise and lower the boom 30, or operate the work table operation lever 52 to hold the work table 40 in the neck. By swinging, it is possible to move the work table 40 on which it is boarded to a desired position.

  Jacks (outrigger jacks) 13 for stably supporting the traveling body 10 are provided at four positions in the front, rear, left and right of the traveling body 10. Each jack 13 includes an outer jack (cylinder tube) 13a provided to extend downward on a side portion of the traveling body 10, and an inner jack (piston rod) 13b provided to be movable in the vertical direction in the outer jack 13a. And a ground plate 13c attached to the lower end of the inner jack 13b. In the present embodiment, a jack base JB for increasing the coefficient of friction with the ground is fixed to the lower surface of the ground plate 13c. The outer jack 13a and the inner jack 13b constitute a hydraulic cylinder (referred to as a jack cylinder JC, see FIG. 1), and the pressure oil from the hydraulic pump P is passed through the jack operation valve Jv controlled by the controller 60. Each jack cylinder JC can be extended (the operation of extending the jack 13) or contracted (the operation of retracting the jack 13). The jack base JB fixed to the lower surface of the ground plate 13c can also be removed from the ground plate 13c. In this case, before the operator overhangs the jack 13, the ground plate 13c is grounded on the road. The jack base JB is placed in advance at a place where it will be.

  A rear operating device 14 is provided at the rearmost part of the traveling body 10, and the jack operating valve Jv can be operated by operating a jack operating lever 53 (see FIG. 1) provided in the rear operating device 14. Thus, the operator can perform the overhanging storage operation of the jack 13. There are a total of four jack operation levers 53 corresponding to the four jacks 13, respectively, so that the four jacks 13 can be individually operated (in FIG. 1, for the sake of convenience, the jack operation levers 53 are provided). Shows only one). If all these four jacks 13 are extended downward (extension operation) and brought into a grounded state, the traveling body 10 can be stably supported and resists a large overturning moment acting on the traveling body 10 during work. Will be able to.

  The boom 30 is stored when not in use. The boom 30 is retracted by lying down until the tip of the boom 30 is in a substantially horizontal posture with the front end of the traveling body 10 facing forward. When the boom 30 is in the retracted position, the proximal boom 30a comes into contact with the boom receiver 15 (see FIG. 2) provided so as to extend upward from the traveling body 10 from above. In the retracted posture of the boom 30, the work table 40 is mounted on the work table mounting table 16 provided on the upper surface of the operation cabin 12.

  When performing an aerial work at a work site using the aerial work vehicle 1 having such a configuration, the operator first operates the jack operation lever 53 from the rear operation device 14 provided at the rearmost part of the traveling body 10. The overhanging operation of each jack 13 is performed. As a result, when all (four) jacks 13 are in the grounded state, they enter the work table 40 from the traveling body 10 and operate the boom operation lever 51 and the work table operation lever 52 to move the work table 40 to the work place at a high place. Let Here, after the extension operation of the jack 13, it is necessary to visually check the grounding state of the jack 13 and then shift to a work at a high place. A safety device is provided to prevent a shift to work at a high place without visual confirmation. The configuration will be described below.

  As shown in FIG. 1, the safety device provided in the aerial work platform 1 includes a ground state confirmation switch 71 operated by an operator who visually confirms the ground state of the jack 13, and all jacks 13 are in a ground state. The jack grounding completion switch 82 for detecting that the grounding state confirmation switch 71 is operated after the jack grounding completion switch 82 detects that all the jacks 13 are in the grounding state. An interlock circuit 80 that enables operation of the boom 30 by the controller 60 is configured. The ground state confirmation switch 71 is provided to force the operator to visually confirm the ground state of the jack 13 after overhanging. The ground state of at least one of the four jacks 13 is determined. It is provided at a position where it can be operated at a position where it can be visually confirmed. In the present embodiment, out of the four jacks 13 provided on the front, rear, left and right of the traveling body 10, the traveling body 10 cannot be seen directly from the position of the rear operation device 14, and the traveling body 10 is stopped near the road shoulder. This grounding state confirmation switch 71 is provided at a position near the jack 13 on the front left side of the traveling body 10 that is installed at a position where it is easy to step on a level (see FIG. 2).

  The jack grounding completion switch 82 is interposed in a second electric wire L2, which will be described later. The jack grounding switch 82 is turned on when any of the four jacks 13 is grounded, and any one of the four jacks 13 is grounded. It is off when not. The jack grounding completion switch 82 is energized only when, for example, limit switches (four in total) that are turned on when each jack 13 is grounded, and when all (four) limit switches are turned on. This switch (jack grounding completion switch) 82 can be configured in combination with a coil that turns on.

  As shown in FIG. 1, the interlock circuit 80 includes a power supply 81, a boom storage switch 83, a relay 84, the above-described controller 60, and an interlock valve 85.

  Here, the power supply 81 is a DC 24-volt power supply, and is turned on by operating the power-on switch 81a. This power-on switch 81a may be prepared exclusively for the power supply 81, but is also used as a PTO switch (not shown) for turning on a power take-off PTO for transmitting the power of the traveling engine EG to the hydraulic pump P. It may be. At this time, the power supply 81 is also turned on simultaneously with the power take-off PTO being turned on. The positive terminal of the power source 81 is connected to the positive terminal side electric wire PL, and the negative terminal is connected to the grounded negative terminal side electric wire NL. As shown in FIG. Two electric wires L2, a third electric wire L3, and a fourth electric wire L4 are connected in parallel. However, the first electric wire L1 is provided between the positive terminal side electric wire PL and the negative terminal side electric wire NL, and the second electric wire L2 is provided between the positive terminal side electric wire PL and the intermediate portion of the first electric wire L1. The third electric wire L3 is provided between the positive terminal side electric wire PL and the intermediate portion of the second electric wire L2, and the fourth electric wire L4 is provided between the positive terminal side electric wire PL and the controller 60. .

  The boom retracting switch 83 is a so-called B contact type switch interposed in the third electric wire L3. When the boom 30 is in the retracted state, that is, the proximal boom 30a is in contact with the boom receiver 15 from above. In the state, the base end boom 30a is pressed to turn off, and when the base end boom 30a is separated from the boom receiver 15, the press is released to turn on.

  As shown in FIG. 1, the relay 84 includes a coil 84a, a first switch 84b, and a second switch 84c. The coil 84a is interposed in the first electric wire L1 in series with the ground state confirmation switch 71 (the ground state confirmation switch 71 is on the positive terminal side electric wire PL side), and the second electric wire L2 is on the first electric wire L1. Is connected between the ground state confirmation switch 71 and the coil 84a. Here, the ground state confirmation switch 71 is a push button type switch that is turned on only during the pressing operation. The first switch 84b is interposed in the second electric wire L2 in series with the jack grounding completion switch 82 (the jack grounding completion switch 82 is on the positive terminal side electric wire PL side), and when the coil 84a is excited. It is attracted to the coil 84a and turned on, and turned off when the coil 84a is not excited. The second switch 84c is interposed in the fourth electric wire L4, and is attracted to the coil 84a when the coil 84a is excited and turned on, and turned off when the coil 84a is not excited. Here, in a state where the second switch 84c is on, a voltage signal (this voltage signal is hereinafter referred to as an interlock valve switching signal) is sent to the controller 60.

  The interlock valve 85 is a two-position switching valve having a jack operable position and a boom operable position. When the interlock valve 85 is positioned at the jack operable position, the interlock valve 85 includes a valve group consisting of four jack operating valves JV (hereinafter referred to as a jack operating valve group). Pressure oil is supplied to an oil passage JL connected to TJV), but a valve group including a swing motor operation valve 23a, a hoisting cylinder operation valve 24a, a telescopic cylinder operation valve 31a, and a swing motor operation valve 42a (hereinafter referred to as boom operation). No pressure oil is supplied to the oil passage BL connected to the valve group TBV), and pressure oil is supplied to the oil passage BL connected to the boom operation valve group TBV in the state where the boom operation valve group TBV is located. No pressure oil is supplied to the oil passage JL connected to the group TJV. The controller 60 performs the position switching operation of the interlock valve 85. Specifically, the interlock valve 85 can jack a spool (not shown) by the biasing force of a built-in spring (not shown) when the above-described interlock valve switching signal is not input from the controller 60. When the interlock valve switching signal is input, the spool attracted by a built-in solenoid (not shown) moves against the urging force of the spring and is positioned at the boom operable position. To do.

  Next, the operation of the safety device having the above configuration will be described. When working at a high place with the aerial work vehicle 1, the operator first drives the aerial work vehicle 1 from the driving cabin 12 and moves to the work site. At this time, all the jacks 13 and the booms 30 are moved. Since it is in the retracted state, the jack grounding completion switch 82 and the boom retracting switch 83 are both turned off while the aerial work vehicle 1 is traveling on the road. Accordingly, during that time, the coil 84a is in a non-excited state, and both the first switch 84b and the second switch 84c are off. Therefore, the interlock valve switching signal is not input to the controller 60, and the interlock valve 85 is located at the jack operable position.

  When the aerial work vehicle 1 arrives at the work site, the operator operates the jack operation lever 53 from the rear operation device 14 to project each jack 13. At this time, since the interlock valve 85 is positioned at the jack operable position as described above, the pressure oil of the hydraulic pump P is supplied to the oil passage JL connected to the jack operation valve group TJV, and each jack 13 is connected to the jack operation lever 53. It operates according to the operation of (here, extends downward). In this state, since the hydraulic oil of the hydraulic pump P is not supplied to the boom operation valve group TBV, the boom operation lever 51 or the work table operation lever 52 is operated, and the valves 23v, 24v, 31v, Even if each spool of 42v is driven by the controller 60, the boom 30 does not actually operate. (Interlock function that prevents the boom 30 from being operated when the jack 13 can be operated by the interlock circuit 80).

  When all (four) jacks 13 are grounded, the jack grounding completion switch 82 is turned on. As described above, when the jack grounding completion switch 82 is turned on, a lamp or the like (not shown) provided on the traveling body 10 is turned on via the controller 60 so that the operator is informed accordingly. It is preferable.

  When the operation of overhanging the jacks 13 is completed, the operator visually checks the grounding state of each jack 13. At this time, it should be noted that the ground is not loose or not slippery (including confirmation of the slope of the road surface, the wetness of the road surface, etc.), and the grounding plate 13c includes stones, stairs and side grooves. It is whether or not there is a factor behind the jack 13 that cannot support the inclination of the traveling body after the start of work, such as whether it is caught in a place with a step. In the case of the aerial work vehicle 1 according to the present embodiment, the grounding state confirmation switch 71 is provided in the vicinity of the jack 13 provided on the front left side of the traveling body 10, so that the operator can operate the extension of each jack 13. After that, it is necessary to leave the position of the rear operation device 14 provided with the jack operation lever 53 and move to the front left side of the traveling body 10, and sufficiently check the grounding state of the jack 13 together with the other three jacks 13. Will be confirmed.

  After confirming the grounding state of all (four) jacks 13, the operator presses the grounding state confirmation switch 71 provided in the vicinity of the jack 13 on the front left side of the traveling body 10. When the ground state confirmation switch 71 is pressed, a current flows through the first electric wire L1, so the coil 84a is excited, and both the first switch 84b and the second switch 84c attracted to the coil 84a are turned on. When the second switch 84c is turned on, an interlock valve switching signal is input to the controller 60 from the fourth electric wire L4. The controller 60 moves the interlock valve 85 from the position where the jack can be operated to the boom. Switch to the operable position. As a result, the operation of the boom 30 can be performed for the first time, and in the state where the operation of the boom 30 is enabled as described above, the jack 13 cannot be operated.

  As described above, in this safety device, the interlock valve 85 is configured not to be switched from the jack operable position to the boom operable position unless the second switch 84c is turned on. For this reason, the operator not only performs the overhanging operation of the jack 13 but also confirms the grounding state of the jack 13 provided at least on the front left side of the traveling body 10 and then touches the grounding state confirmation switch 71 provided in the vicinity thereof. The boom 30 cannot be operated without operating (the boom 30 is operated even if all the jacks 13 are grounded by the interlock circuit 80 unless the grounding state confirmation switch 71 is operated. Interlock function to prevent that).

  By the way, when the ground state confirmation switch 71 is pressed, the first switch 84b is closed together with the second switch 84c as described above, so that the coil 84a and the fourth electric wire L4 have a current flowing through the first electric wire L1. It will be in the state excited by both the electric current which flows through. For this reason, even if the operator presses the ground state confirmation switch 71 and immediately releases the finger from the switch 71 (releases the pressing operation), the coil 84a remains in the excited state, and the first switch 84b and the first switch Both the two switches 84c are kept on. (So-called relay self-holding state)

  In the state where the interlock valve 85 is switched to the boom operable position as described above, the pressure oil of the hydraulic pump P is supplied to the oil passage BL connected to the boom operation valve group TBV. The telescopic cylinder 31 operates according to the operation of the boom operation lever 51, and the swing motor 42 operates according to the operation of the worktable operation lever 52. In the state where the interlock valve 85 is switched to the boom operable position as described above, the pressure oil of the hydraulic pump P is not supplied to the oil passage JL connected to the jack operation valve group TJV. 53, and even if the spool of the jack valve Jv corresponding to each jack cylinder JC is driven by the controller 60, the jack 13 does not actually operate (the boom by the interlock circuit 80). (Interlock function that prevents the jack 13 from being operated in a state in which 30 can be operated).

  When the operation of the boom 30 is started (specifically, the boom 30 is lifted from the retracted posture), the proximal boom 30a is separated from the boom receiver 15, so that the boom retracting switch 83 receives the pressing force from the proximal boom 30a. It is solved and turned on. As a result, a current also flows through the third electric wire L3, and the coil 84a is excited by both the current flowing through the second electric wire L2 and the current flowing through the third electric wire L3.

  During the work at a high place, the traveling body 10 may be inclined with respect to the ground, and one of the four jacks 13 may be lifted off the ground (a plurality of jacks may be simultaneously lifted off the ground). Is also possible). Although the traveling body 10 is not at risk of falling even in such a state, the jack grounding completion switch 82 is turned off because one (or a plurality) of the jacks 13 are not grounded. End up. However, the coil 84a is excited by both the current flowing through the second electric wire L2 and the current flowing through the third electric wire L3 until just before the jack grounding completion switch 82 is turned off as described above. Even if the jack grounding completion switch 82 is turned off, the excitation state of the coil 84a is maintained, and the second switch 84c is kept on. For this reason, even if the traveling body 10 is tilted and one jack 13 is lifted off the ground, the interlock valve switching signal input to the controller 60 is not interrupted, and the operation of the boom 30 is continued. Is possible.

  When the required height work is completed, the operator on the work table 40 operates the boom operation lever 51 and the work table operation lever 52 to put the boom 30 in the retracted state. When the boom 30 is in the retracted state, the proximal boom retract switch 83 is pressed by the proximal boom 30a and turned off, so that the coil 84a is excited only from the current flowing through the second electric wire L2. In this state, since the second switch 84c is still on, the interlock valve switching signal is input to the controller 60, and the interlock valve 85 is maintained in the boom operable position.

  Next, when it comes to the stage where the protruding jacks 13 are retracted, the operator presses the interlock release button 54 provided in the rear operation device 14. When the interlock release button 54 is pressed, an interlock release signal is output to the controller 60. The controller 60 receives the input of the interlock release signal and forcibly turns off the jack grounding completion switch 82. As a result, no current flows through the fourth electric wire L4, and the coil 84a is demagnetized, so that the second switch 84c is turned off (the first switch 84b is also turned off). When the second switch 84c is turned off, the interlock valve switching signal is not input to the controller 60. Therefore, the solenoid of the interlock valve 85 is demagnetized, and the spool is moved by the biasing force of the spring, and the boom operation up to that point is performed. Switch from possible position to jack operable position. As a result, the pressure oil of the hydraulic pump P is supplied to the oil passage JL connected to the jack operation valve group TJV, and each jack 13 can be actuated (here, contracted upward) according to the operation of the jack operation lever 53. It becomes. Further, since the interlock valve 85 is switched to the jack operable position, it is not supplied to the oil passage BL connected to the boom operation valve group TBV, so that the operation of the boom 30 becomes impossible.

  As described above, in the safety device provided in the aerial work platform 1, the boom 30 cannot be operated unless the grounding state confirmation switch 71 is operated after the jack 13 is extended. Therefore, the operator visually checks the grounding state of at least one jack 13 after operating the jack 13 and before operating the grounding state confirmation switch 71. At the time of this visual check, the worker will carefully check the ground condition etc. of the place where the work is going to be done and carefully judge whether it is a suitable place for the work. Since the jack 13 cannot fully support the traveling body 10 after the start, the traveling body 10 does not become an unstable posture, and the safety of work can be improved more than before. It should be noted that the conventional interlock circuit (the interlock that prevents the boom from being operated only after all jacks are extended to the ground state, and the jack cannot be operated when the boom can be operated. In the circuit), if it is detected that all jacks are in contact with the ground, it is usually possible to operate the boom. Therefore, the situation where the jack cannot sufficiently support the inclination of the traveling body after the work starts. However, this safety device overcomes these problems.

  Although the preferred embodiments of the present invention have been described so far, the scope of the present invention is not limited to those shown in the above-described embodiments. For example, in the above-described embodiment, the ground state confirmation switch 71 is provided in the vicinity of the jack 13 on the left front side of the traveling body 10, but the ground state confirmation switch 71 includes at least one of the four jacks 13. It is only necessary to be provided at a position where the ground contact state of the two jacks 13 can be visually confirmed. This is because by confirming the grounding state of one jack 13, at least the ground condition and the like can be confirmed. However, as in the above-described embodiment, that is, like the jack 13 on the front left side of the traveling body 10, the grounding state cannot be directly seen from the rear position of the traveling body 10 provided with the jack operation lever 53. Alternatively, if the ground state confirmation switch 71 is provided in the vicinity of the jack 13 where the ground state is most difficult to see, the operator needs to move to a position near the jack 13 where the switch 71 is provided. Since all the jacks 13 are visually checked for the ground contact state, the operator can find this before the work, and the safety of the work can be further improved.

  Further, in the aerial work vehicle 1 and other types of work vehicles in the present embodiment, there are a plurality of jacks where it is difficult to see the grounding state from the position where the jack operation means (the jack operation lever 53 corresponds in the above embodiment) is provided. If this is the case, a grounding state confirmation means (in the above embodiment, the grounding state confirmation switch 71 is applicable) is provided at a position near each of such jacks, and the boom is not operated after the plurality of grounding state confirmation means are operated. It may be configured such that the operation operation cannot be performed (in the above example, the interlock valve switching signal is not input to the controller 60). Furthermore, even if it is not difficult to see directly, in order to improve safety, grounding state confirmation means are provided in the vicinity of all jacks, and only after these grounding state confirmation means are operated. The boom operation operation may not be performed.

  In the above-described embodiment, there are a total of four jacks 13 provided on the front, rear, left, and right sides of the traveling body 10, but this is only an example and does not necessarily have to be four. Further, in the above-described embodiment, when the interlock release button 54 is pressed, an interlock release signal is output to the controller 60, and the controller 60 that has received the interlock release signal forces the jack grounding completion switch 82 to be forced. Although it is configured to be turned off, the interlock release button 54 may be provided adjacent to the coil 84a in series, or may be configured as an open / close switch that cuts off the current flowing through the coil 84a when pressed. Further, although the ground state confirmation switch 71 is provided in the vicinity of the jack 13 in the above-described embodiment, it may of course be provided in the jack 13 itself. Furthermore, although the ground state confirmation switch 71 is a push button type in the above-described embodiment, this is an example, and other types may be used.

  Moreover, although the interlock valve 85 in the above-described embodiment is a two-position switching valve having a jack operable position and a boom operable position, any one of the neutral position (the jack operable position and the boom operable position) can be used. Alternatively, a three-position valve to which pressure oil is not supplied) may be used. At this time, when neither the boom 30 nor the jack 13 is operated (for example, when the power-on switch 81a is off) such as when the vehicle is running, the spool of the interlock valve is positioned at the neutral position and the power-on switch 81a is turned on. When operated, the controller 60 switches the interlock valve spool to the jack operable position, and when the interlock valve switching signal is output from the interlock circuit 80, the controller 60 can operate the interlock valve spool. What is necessary is just to set it as the structure switched to a position.

  In the above-described embodiment, the interlock circuit 80 sends an interlock switching signal to the controller 60 when it is necessary to switch the interlock valve 85 from the jack operable position to the boom operable position. When the switching signal is received, the interlock valve is switched from the jack operable position to the boom operable position (that is, the interlock circuit 80 intermittently inputs the signal to the controller 60). Instead of such a configuration, the controller 60 always outputs a signal for switching the interlock valve 85 from the jack operable position to the boom operable position after the power take-off PTO is turned on. The circuit 80 is A configuration in which the above-mentioned signal (a signal output from the controller 60 to the interlock valve 85) is cut off when the turlock valve 85 is to be positioned at a jack operable position (that is, a configuration in which the interlock circuit 80 interrupts the output signal from the controller 60) ).

  In addition, the interlock circuit 80 shown in the present embodiment is used when the operation of the ground state confirmation switch 71 (whether one is plural or not) is performed after all the jacks 13 are grounded. It is sufficient that the controller 60 has a function of enabling the boom to be operated (the boom 30 can be operated only after the operation of the ground state confirmation switch 71 is performed after all the jacks 13 are grounded). The configuration is not limited to that shown in the above-described embodiment. Further, in the above-described embodiment, the target to which the safety device of the present invention is applied is an aerial work vehicle. As long as the traveling body is provided with a boom and a jack having the above, it can be similarly applied to other types of work vehicles (for example, a crane vehicle).

It is a figure showing composition of a boom, a power system of a jack, an interlock circuit, etc. in an aerial work vehicle provided with a safety device concerning one embodiment of the present invention. It is the perspective view which looked at the aerial work vehicle from the rear upper side.

Explanation of symbols

1 High-altitude work vehicle (work vehicle)
10 traveling body 13 jack 30 boom 40 work table (working device)
51 Boom operation lever (boom operation means)
53 Jack operation lever (jack operation means)
60 controller (boom operation control means)
71 Ground state confirmation switch (ground state confirmation means)
80 Interlock circuit 82 Jack grounding completion switch (grounding state detection means)

Claims (2)

A traveling body,
A boom provided on the traveling body and having a working device at a tip;
Jacks that are provided at a plurality of locations of the traveling body and support the traveling body in a grounded state protruding downward;
Boom operating means for operating the boom;
Boom operation control means for operating the boom in response to an operation of the boom operation means;
Among the plurality of jacks, at least one of the jacks is provided so as to be operable at a position where the grounding state can be visually confirmed, and a grounding state confirmation means for prompting the worker to visually confirm the grounding state
Grounding state detecting means for detecting that all of the plurality of jacks are in a grounded state;
After the ground state detection means detects that all of the plurality of jacks are in the ground state, the operation of the boom by the boom operation control means is performed when the ground state confirmation means is operated. A work vehicle safety device comprising an interlock circuit that enables the work vehicle.   The traveling body has jack operating means for performing an extension operation of the jack, and the grounding state confirmation means is provided in a position near the jack where the grounding state cannot be directly seen from the position where the jack operating means is provided. 2. The work vehicle safety device according to claim 1, wherein the work vehicle safety device is provided.

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