JP2007276943A - Simultaneous operation restriction mechanism and fork lift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fork lift capable of, even if unlocking of a container lock device is failed and a freight car is lifted up with a container without restricting the order of action, easily descending the freight car to an original position without derailing from a rail. <P>SOLUTION: A lift side proximity switch 39 and a tilt side proximity switch 40 for detecting the operation states of a lift lever LE and a tilt lever LT are provided. A shut valve 36 for switching an oil passage to the communication state and the shutt-off state is provided on the oil passage for feeding an operation oil to a lift cylinder 22 and a tilt cylinder 32. Further, a relay circuit 41 comprising an always opened contact 41a and a coil 41b is connected between the respective switches 39, 40 and the shut valve 36. Further, when operation of both levers LE, LT is detected by the respective switches 39, 40, the always opened contact 41a of the relay circuit 41 is made closed to energize a solenoid 38 of the shut valve 36 and the oil passage is switched from the communication state to the shut-off state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a simultaneous operation restriction mechanism for restricting simultaneous operation of a lifting operation means for operating a lifting device and a tilting operation means for operating a tilting device, and a forklift equipped with the simultaneous operation restriction mechanism.

  Conventionally, when a container is transported using a railway, a forklift is mainly used for a cargo handling operation of placing the container on a wagon or moving the container placed on the freight car.

  Next, an example of work for moving the container 60 placed on the freight car 62 will be described with reference to FIG. The container 60 is fixed to the freight car 62 by a container lock device 61. The freight car 62 rides on the rail 68 so that the rib portion of the wheel 66 enters the inside of the rail 68 and does not derail. The operator unlocks the container locking device 61 to release the container 60 and inserts the fork 24 of the forklift 1 into the lower part of the container 60 to lift and move the container 60.

  The fork 24 of the forklift 1 is provided in an elevating device (consisting of a lift bracket 23, an elevating cylinder 22 (see FIG. 1), etc.) that can move up and down along the mast 20. Further, the mast 20 includes a tilt device (comprising a tilt cylinder 32 or the like) that can adjust the forward tilt angle or the rear tilt angle so that the lifted container 60 can be moved more stably.

  Here, when the operator forgets to unlock the container locking device 61, if the freight car 62 is lifted together with the container 60 only by the raising operation of the fork 24, the fork 24 is lowered as it is. When operated, it can be returned to its original position relatively easily (returning so that the freight car 62 does not derail from the rail 68). Further, even when the freight car 62 is lifted together with the container 60 only by the backward tilting operation of the mast 20, if the mast 20 is tilted forward to the original position, it can be returned to the original position relatively easily. Is possible.

  However, without noticing that the user has forgotten to unlock, the freight car 62 is also lifted together with the container 60, and further, two operations of the fork 24 ascending operation (elevating operation) and the mast 20 tilting operation (tilting operation) are performed. It is very difficult to return the freight car 62 to its original position so as not to derail the rail 68. Moreover, it has returned to the original position over a long time.

Such a situation is due to the fact that two different operations, that is, the raising operation of the fork 24 and the backward tilting operation of the mast 20 can be performed simultaneously.
For example, Patent Document 1 has been proposed as a configuration in which two different operations are not performed simultaneously. In Patent Document 1, in a retractable boom device that operates a hoisting boom and a bending boom with hydraulic pressure, when moving the work platform to a high place, first, hydraulic oil is supplied only to the hoisting boom, and the hoisting boom is fully extended. After that, the hydraulic circuit is configured so that hydraulic oil is supplied to the bending boom. This prior art uses two sequence and check valves to control the opening and closing of the hydraulic circuit that supplies hydraulic oil to the bending boom cylinder using the hydraulic pressure that operates the hoisting boom cylinder to operate the bending boom cylinder. The hydraulic circuit that supplies hydraulic oil to the hoisting boom cylinder is controlled to open and close using hydraulic pressure. With this configuration, the hoisting boom and the bending boom do not operate at the same time. The folding boom is started to be folded, and a configuration is proposed in which the two booms do not operate simultaneously.
Japanese Utility Model Publication No. 6-45996

  In the prior art described in Patent Document 1, the two booms of the hoisting boom and the bending boom are not operated simultaneously, but the operation order is fixed. That is, when the boom is extended, the extension boom is started after the extension boom is extended, and when the boom is folded, the extension boom is started after the extension boom is completed.

  However, in the forklift 1, the operation sequence of the raising / lowering operation (up or down operation) of the fork 24 and the tilt operation (forward or backward operation) of the mast 20 is fixed. Since workability may be lowered, it is not preferable.

  The present invention has been made paying attention to such problems existing in the prior art, and the object thereof is to simultaneously perform the lifting operation means and the tilting operation means in a vehicle equipped with the lifting apparatus and the tilting apparatus. An object is to provide a simultaneous operation restriction mechanism capable of restricting operations. In addition, another object of the present invention is to limit the operation order, and even if the container lock device is forgotten to be unlocked and the freight car is lifted together with the container, the original order can be restored without derailing the rail. The object is to provide a forklift that can be easily lowered depending on the position.

  In order to solve the above-mentioned problems, the invention according to claim 1 includes a lifting device that lifts and lowers a cargo handling device provided on a mast by hydraulic pressure, a lifting operation means that operates when operating the lifting device, The vehicle is equipped with a tilting device that tilts the mast by hydraulic pressure, and a tilting operation unit that operates when operating the tilting device, and the lifting operation unit and the tilting operation unit are operated simultaneously. A simultaneous operation restriction mechanism for restricting simultaneous operation of the elevating device and the tilting device, a detection switch for detecting an operation state of the elevating operation unit and an operation state of the tilting operation unit, the elevating device, and the tilting An electromagnetic switching valve disposed on an oil passage for supplying hydraulic oil to the apparatus and switching between a shut-off state for shutting off the oil passage and a communication state for communicating the oil passage; Electricity connected between the electromagnetic switching valve and for controlling the energization state of the electromagnetic switching valve so as to switch the oil passage from the communication state to the cutoff state and from the cutoff state to the communication state based on the detection state of the detection switch. A circuit, and the electric circuit controls the energization state of the electromagnetic switching valve so that the oil passage is switched from the communication state to the shut-off state when the lifting operation means and the tilting operation means are operated simultaneously. The gist is to do.

  According to this, simultaneous operation of the elevating operation means and the tilt operation means can be restricted in a vehicle including the elevating apparatus and the tilting apparatus. In the present invention, the simultaneous operation of the lifting operation means and the tilting operation means is performed by adding a simultaneous operation restriction mechanism comprising a detection switch, an electromagnetic switching valve and an electric circuit to the hydraulic mechanism for operating the lifting device and the tilting device. Can be limited. Therefore, it is possible to equip not only the vehicle before the sale but also the vehicle after the sale with a simultaneous operation restriction mechanism without making a significant design change.

  According to a second aspect of the present invention, in the simultaneous operation limiting mechanism according to the first aspect, the detection switch includes a first switch for detecting an operation state of the elevating operation means and an operation state of the tilt operation means. The first switch and the second switch are connected in series, and the electric circuit is connected in series with the normally open contact connected to the electromagnetic switching valve and each switch. A single relay circuit having a coil to be connected or a normally closed contact connected to the electromagnetic switching valve and a coil connected in series to each switch, wherein the first switch is the first switch The electromagnetic switching valve is energized when an operation of the lifting operation means is detected and the second switch detects an operation of the tilt operation means, and the electromagnetic switching valve is operated when the relay circuit has a normally open contact. When the normally open contact can be closed by excitation, the oil passage is switched from the communication state to the cut-off state, while when the relay circuit has a normally closed contact, the coil is excited. The gist is that when the normally closed contact can be in an open state, it is de-energized and the oil passage is switched from a communication state to a cut-off state.

  According to a third aspect of the present invention, in the simultaneous operation limiting mechanism according to the first aspect, the detection switch includes a first switch for detecting an operation state of the lifting operation means and an operation state of the tilt operation means. A first relay circuit having a normally open contact and a coil connected in series with the first switch; and a normally open contact of the first relay circuit. A normally open contact connected in series to the second switch and a coil connected in series to the second switch; a normally open contact or a normally closed contact connected to the electromagnetic switching valve; And a third relay circuit having a coil connected in series with the open contact, wherein the third switch detects the operation of the lifting operation means and the second switch The tilting operation hand When the third relay circuit has a normally open contact, the electromagnetic switching valve is energized when the normally open contact can be closed by excitation of the coil. When the third relay circuit has a normally closed contact, the normally closed contact can be opened by excitation of the coil while the oil passage is switched from the communication state to the cut-off state. The gist is to switch the oil passage from the communication state to the shut-off state.

  According to a fourth aspect of the present invention, in the simultaneous operation limiting mechanism according to the first aspect, the detection switch includes a first switch for detecting an operation state of the elevating operation means and an operation state of the tilt operation means. A first relay circuit having a normally open contact and a coil connected in series with the first switch; and a normally open contact of the first relay circuit. And a second relay circuit having a normally open contact connected to the electromagnetic switching valve and a coil connected in series to the second switch, and the electromagnetic switching valve includes both relay circuits. The gist is that the coil is energized by being excited together and the oil passage is switched from the communication state to the shut-off state.

  According to the second to fourth aspects of the invention, the energization state of the electromagnetic switching valve can be controlled using the detection switch and the relay circuit, and the simultaneous operation limiting mechanism can be realized with a simple configuration. In the invention of claim 3, the electromagnetic switching valve can be controlled using a single relay circuit by connecting the detection switches in series, and the simultaneous operation limiting mechanism can be realized with a simpler configuration.

The gist of the invention described in claim 5 is that the simultaneous operation restriction mechanism described in any one of claims 1 to 4 is provided.
According to this, the simultaneous operation of the lifting operation means and the tilting operation means can be restricted by the simultaneous operation restriction mechanism. Therefore, in the forklift of the present invention, even if the container lock device is forgotten to be unlocked and the freight car is lifted together with the container without restricting the operation sequence, the original position is not derailed from the rail. Can be taken down easily.

  According to the simultaneous operation restriction mechanism of the present invention, it is possible to restrict the simultaneous operation of the lifting operation means and the tilting operation means in a vehicle including the lifting device and the tilting device. And according to the forklift equipped with the simultaneous operation restriction mechanism of the present invention, even if you forget to unlock the container locking device and lift the wagon together with the container without restricting the operation sequence, It can be easily lowered by the original position without derailing.

(First embodiment)
A first embodiment embodying the present invention will be described below with reference to FIGS.
The forklift includes an elevating device that allows the fork 24 provided on the mast 20 to move up and down (elevating operation). Further, the forklift is provided with a tilting device (tilt device) that can adjust the forward tilt angle and the rearward tilt angle of the mast 20, that is, the mast 20 can be tilted back and forth (tilt operation).

  An elevating piston 22b that can move up and down along the elevating cylinder 22 is provided in the elevating cylinder 22 constituting the elevating device. Further, a lift side hydraulic chamber 22a for pushing up the lift piston 22b with hydraulic pressure is provided in the lift cylinder 22. The lifting cylinder 22 is provided in the mast 20. A lift chain LC is provided in the mast 20, one end of the lift chain LC is fixed to the mast 20, and the other end is connected to a lift bracket 23 provided with a fork 24. A chain wheel CW to which a lift chain LC is applied is provided at the upper end of the lifting piston 22b, and the fork 24 moves up and down by the lifting and lowering operation of the lifting piston 22b.

  A pipe H <b> 13 for supplying and discharging hydraulic oil from the lifting control valve 25 is connected to the rising side hydraulic chamber 22 a in the lifting cylinder 22. In addition, the lifting control valve 25 returns the piping HP from the oil pump P that is a supply source of the hydraulic oil supplied to the ascending hydraulic chamber 22a and the hydraulic oil discharged from the ascending hydraulic chamber 22a to the oil tank T. The pipe LP is connected. The lift control valve 25 is connected to pipes H1 and H2 from a pilot valve 25a that controls the supply and discharge of hydraulic oil that controls the valve position of the lift control valve 25.

  The pilot valve 25a is directly connected to an elevating lever LE as an elevating operation means provided at the driver's seat of the forklift. The elevating lever LE is a means operated by the driver when instructing the elevating operation of the fork 24. The elevating lever LE is configured to be tilted between a neutral position and an ascending instruction position and a descending instruction position across the neutral position. The ascending instruction position is a position for instructing the ascending movement of the fork 24, the descending instruction position is a position for instructing the descending movement of the fork 24, and the neutral position is a position where neither the ascending movement nor the descending movement can be instructed. is there. Therefore, the driver operates the elevating lever LE to the ascending instruction position when instructing the ascending movement of the fork 24, while operating the elevating lever LE to the descending instruction position when instructing the lowering movement of the fork 24. By these operations, the valve position of the pilot valve 25a is directly operated.

  The pilot valve 25 a has a pipe H <b> 4 to which hydraulic oil from the oil pump P is supplied, pipes H <b> 1 and H <b> 2 for supplying and discharging hydraulic oil to and from the lift control valve 25, and an action discharged from the lift control valve 25. A pipe H5 for returning oil to the oil tank T is connected. The pipe H4 is connected to the pipe HP, and the pipe H5 is connected to the pipe LP. The pilot valve 25a can supply the hydraulic oil supplied from the oil pump P to the elevation control valve 25 or discharge the hydraulic oil in the elevation control valve 25 based on the operation of the elevation lever LE. The valve position in the control valve 25 is controlled (that is, the position of the lift piston 22b of the lift cylinder 22 is controlled).

  For example, when the elevating lever LE is operated to the ascending side, i7 and s7b in the pilot valve 25a are connected, and the hydraulic oil supplied from the oil pump P is the valve drive oil for the elevating control valve 25 via the pipe H2. It is supplied to the chamber (upward side). Also, e7 and s7a in the pilot valve 25a are connected, and the hydraulic oil in the valve drive oil chamber (downward side) of the lift control valve 25 is discharged via the pipe H1. As a result, the valve position in the lift control valve 25 is controlled. In the lift control valve 25, i5 and s5c are connected, hydraulic oil is supplied from the oil pump P to the lift side hydraulic chamber 22a, and the lift piston 22b is To rise.

  Further, when the lifting lever LE is operated to the lowering side, e7 and s7b in the pilot valve 25a are connected, and the hydraulic oil in the valve drive oil chamber (upward side) of the lifting control valve 25 is discharged via the pipe H2. Is done. Further, i7 and s7a in the pilot valve 25a are connected, and the hydraulic oil supplied from the oil pump P is supplied to the valve drive oil chamber (downward side) of the lift control valve 25 via the pipe H1. As a result, the valve position in the lift control valve 25 is controlled. In the lift control valve 25, e5 and s5c are connected, the hydraulic oil is discharged from the lift side hydraulic chamber 22a, and the lift piston 22b is lowered.

  When the elevating lever LE is operated to the neutral position, e7 and s7b are connected in the pilot valve 25a, and hydraulic oil is discharged from the valve drive oil chamber (upward side) in the elevating control valve 25, and e7 And s7a are connected, and hydraulic oil is discharged from the valve drive oil chamber (downward side) in the elevation control valve 25. Then, the valve position in the elevation control valve 25 is returned to the default position, s5c is closed, and the hydraulic oil in the ascending hydraulic chamber 22a is maintained.

  The tilt cylinder 32 that constitutes the tilting device is provided with a tilt piston 32 b that can move along the tilt cylinder 32. Further, in the tilt cylinder 32, a forward tilt side hydraulic chamber 32a and a rear tilt side hydraulic chamber 32c for moving the tilt piston 32b with hydraulic pressure are provided. The mast 20 is connected to the tip of the tilt piston 32b.

  A pipe H7 for supplying and discharging hydraulic oil from the tilt control valve 35 is connected to the forward tilt side hydraulic chamber 32a in the tilt cylinder 32, and the hydraulic oil is also supplied from the tilt control valve 35 to the rear tilt side hydraulic chamber 32c. A discharge pipe H6 is connected. Further, the tilt control valve 35 includes a pipe HP from an oil pump P that is a supply source of hydraulic oil supplied to each of the forward tilt side hydraulic chamber 32a and the rear tilt side hydraulic chamber 32c, and the forward tilt side hydraulic chamber 32a and the rear tilt side hydraulic pressure. A pipe LP for returning the hydraulic oil discharged from each of the chambers 32c to the oil tank T is connected. The tilt control valve 35 is connected to pipes H8 and H9 from a pilot valve 35a for controlling supply and discharge of hydraulic oil for controlling the valve position of the tilt control valve 35.

  The pilot valve 35a is directly connected to a tilt lever LT as a tilt operating means provided at the driver's seat of the forklift. The tilt lever LT is a means operated by the driver when the mast 20 is instructed to tilt forward and backward. The tilt lever LT is configured to be capable of tilting between a neutral position and a forward tilt instruction position and a rear tilt instruction position across the neutral position. The forward tilt instruction position is a position for instructing the forward movement of the mast 20, the backward inclination instruction position is a position for instructing the backward movement of the mast 20, and the neutral position is both forward and backward movement. It is a position that cannot be indicated. Therefore, the driver operates the tilt lever LT to the forward tilt instruction position when instructing the forward tilt movement of the mast 20, while tilting the tilt lever LT backward when instructing the backward tilt movement of the mast 20. By operating to the indicated position, the valve position of the pilot valve 35a is directly operated by these operations.

  The pilot valve 35a includes a pipe H10 to which hydraulic oil from the oil pump P is supplied, pipes H8 and H9 for supplying and discharging hydraulic oil to and from the tilt control valve 35, and an action discharged from the tilt control valve 35. A pipe H11 for returning oil to the oil tank T is connected. The pipe H10 is connected to the pipe HP, and the pipe H11 is connected to the pipe LP. The pilot valve 35a can supply the hydraulic oil supplied from the oil pump P to the tilt control valve 35 or discharge the hydraulic oil in the tilt control valve 35 based on the operation of the tilt lever LT. The valve position in the control valve 35 is controlled. That is, the position of the tilt piston 32b of the tilt cylinder 32 is controlled.

  For example, when the tilt lever LT is operated to the forward tilt side, i8 and s8b in the pilot valve 35a are connected, and the hydraulic oil supplied from the oil pump P is the valve drive oil for the tilt control valve 35 via the pipe H9. Supplied to the chamber (forward tilt side). Further, e8 and s8a in the pilot valve 35a are connected, and the hydraulic oil in the valve drive oil chamber (rearly inclined side) of the tilt control valve 35 is discharged via the pipe H8. As a result, the valve position in the tilt control valve 35 is controlled. In the tilt control valve 35, i6 and s6d are connected, and hydraulic oil is supplied from the oil pump P to the forward tilt side hydraulic chamber 32a. s6c is connected, the hydraulic oil is discharged from the backward inclined hydraulic chamber 32c, and the tilt piston 32b rises.

  Further, when the tilt lever LT is operated to the lowering side, e8 and s8b in the pilot valve 35a are connected, and the hydraulic oil in the valve drive oil chamber (forward tilt side) of the tilt control valve 35 is discharged via the pipe H9. Is done. Also, i8 and s8a in the pilot valve 35a are connected, and the hydraulic oil supplied from the oil pump P is supplied to the valve drive oil chamber (rearly inclined side) of the tilt control valve 35 through the pipe H8. As a result, the valve position in the tilt control valve 35 is controlled. In the tilt control valve 35, i6 and s6c are connected, and hydraulic oil is supplied from the oil pump P to the backward tilt side hydraulic chamber 32c. s6d is connected, the hydraulic oil is discharged from the forward inclined hydraulic chamber 32a, and the tilt piston 32b is lowered.

  When the tilt lever LT is operated to the neutral position, in the pilot valve 35a, e8 and s8b are connected, and hydraulic oil is discharged from the valve drive oil chamber (forward tilt side) in the tilt control valve 35, and e8 And s8a are connected, and the hydraulic oil is discharged from the valve drive oil chamber (rear side) in the tilt control valve 35. Then, the valve position in the tilt control valve 35 is returned to the default position, s6c and s6d are closed, and the hydraulic oil in the forward tilt side hydraulic chamber 32a and the hydraulic oil in the rearward tilt side hydraulic chamber 32c are maintained.

  In the forklift of this embodiment, a shut valve 36 as an electromagnetic switching valve is connected to a pipe HP to which an oil pump P is connected in a hydraulic circuit (hydraulic mechanism) configured as described above. The shut valve 36 is connected to the downstream side of the branching portion to the lift control valve 25 and the tilt control valve 35 and to the upstream side of the connecting portion between the pipes H4 and H10 and the pipe HP. Further, in the present embodiment, the shut valve 36 is a solenoid valve having a valve structure capable of switching between two positions, and is a shut-off position that shuts off the pipe HP and a communication position that connects the pipe HP (state in FIG. 1). Are switched to two positions. A spool (not shown) constituting the shut valve 36 is urged to the communication position side by a spring 37, and the shut valve 36 is disposed at a shut-off position when the solenoid 38 is excited, and the solenoid 38 is demagnetized. Sometimes placed in a communicating position. The solenoid 38 is electrically connected to a proximity switch group including a plurality of proximity switches (detection switches) and a relay circuit as an electric circuit. The solenoid 38 is energized and controlled by the electric circuit. Demagnetized.

  The proximity switch group includes a lift side proximity switch 39 as a first detection switch for detecting an operation state (operation position) of the lift lever LE, and a second detection for detecting an operation position (operation state) of the tilt lever LT. It comprises a tilt side proximity switch 40 as a switch.

  The raising / lowering proximity switch 39 is disposed at the connecting portion (near the connecting shaft) between the pilot valve 25a and the raising / lowering lever LE, and detects the operation state of the raising / lowering lever LE that swings around the connecting portion as a swing center. To do. Specifically, the position of the lift side proximity switch 39 is adjusted so that the contact can be opened (OFF state) when the lift lever LE is in the neutral position. When it is operated to the position or the lowering instruction position and tilted by the tilt angle α, the operation is detected and the contact can be in the closed state (ON state). The raising / lowering proximity switch 39 becomes energized when the contact can be closed.

  The tilt side proximity switch 40 is disposed at a connection portion (near the connection shaft) between the pilot valve 35a and the tilt lever LT, and detects an operation state of the tilt lever LT that swings around the connection portion. To do. Specifically, the position of the tilt side proximity switch 40 is adjusted so that the contact can be opened (OFF state) when the tilt lever LT is in the neutral position, and the tilt lever LT is tilted forward. When it is operated to the designated position or the backward tilt designated position and tilted by the tilt angle α, the operation is detected and the contact can be in a closed state (ON state). The tilt side proximity switch 40 becomes energized when the contact can be closed.

  In this embodiment, the lift side proximity switch 39 and the tilt side proximity switch 40 are connected in series, and a power source (not shown) is connected to one terminal of the tilt side proximity switch 40, and the lift side proximity switch is connected to the other terminal. One terminal 39 is connected. The other terminal of the lift side proximity switch 39 is connected to a relay circuit. For this reason, in the proximity switch group composed of the up / down proximity switch 39 and the tilt side proximity switch 40, when both the lift lever LE and the tilt lever LT are operated and the contacts of the switches 39, 40 can be closed. A predetermined voltage is output to the relay circuit and energized. In other words, when only one of the lift lever LE and the tilt lever LT is operated, that is, when only the contact of either one of the switches 39 and 40 can be closed, a predetermined voltage is applied to the relay circuit. Is not output. The predetermined voltage is a voltage set to a value that can excite the coil 41b constituting the relay circuit.

  In the present embodiment, the relay circuit is composed of a single relay circuit 41. The relay circuit 41 includes a normally open contact (a contact) 41a and a coil (electromagnet) 41b. One terminal of the normally open contact 41a is connected to a power source, and the other terminal is the shut valve 36. The solenoid 38 is connected. In addition, one terminal of the coil 41b is connected to the other terminal of the lift side proximity switch 39 and the other terminal is grounded. The normally open contact 41a is switched from the open state to the closed state when the coil 41b is excited. Therefore, in the relay circuit 41, the coil 41b is excited when a voltage is applied from the lift side proximity switch 39, and the normally open contact 41a is switched to the closed state by the excitation of the coil 41b, so that the solenoid 38 of the shut valve 36 is activated. Energize.

  Hereinafter, the operation of the forklift according to the present embodiment will be described with reference to FIGS. 1 and 2A, 2B, and 2C. In the following description, the description will focus on an aspect in which the simultaneous operation of the lifting / lowering operation of the fork 24 and the forward / backward tilting operation of the mast 20 based on the simultaneous operation of the lifting lever LE and the tilt lever LT is prohibited (limited).

  When both the lift lever LE and the tilt lever LT are in the neutral position (when neither of them is operated), the contacts of the lift side proximity switch 39 and the tilt side proximity switch 40 are in an open state (OFF state). ing. For this reason, as shown in FIG. 1, in the relay circuit 41, the normally open contact 41a is maintained in an open state when the coil 41b is demagnetized. As a result, the shut valve 36 is not energized and exists in the communication position, and the hydraulic oil from the oil pump P can be supplied to the pilot valves 25a and 35a, respectively.

  When only the lift lever LE is operated from the state shown in FIG. 1 as shown in FIG. 2A, the contact of the lift side proximity switch 39 is closed, but the contact of the tilt side proximity switch 40 is open. For this reason, the relay circuit 41 is not energized, and the coil 41b remains demagnetized. The normally open contact 41a of the relay circuit 41 is kept open, and the solenoid 38 of the shut valve 36 is not energized. For this reason, the shut valve 36 exists in the communicating position, and the hydraulic oil from the oil pump P can be supplied to the pilot valves 25a and 35a, respectively. Therefore, in the forklift, the valve position in the lift control valve 25 is controlled by the pilot valve 25a based on the operation position of the lift lever LE, and the lift piston 22b moves up and down.

  When only the tilt lever LT is operated as shown in FIG. 2B from the state shown in FIG. 1, the contact of the tilt side proximity switch 40 is closed, but the contact of the elevation side proximity switch 39 is open. For this reason, the relay circuit 41 is not energized, and the coil 41b remains demagnetized. The normally open contact 41a of the relay circuit 41 is kept open, and the solenoid 38 of the shut valve 36 is not energized. For this reason, the shut valve 36 exists in the communicating position, and the hydraulic oil from the oil pump P can be supplied to the pilot valves 25a and 35a, respectively. Therefore, in the forklift, the valve position in the tilt control valve 35 is controlled by the pilot valve 35a based on the operation position of the tilt lever LT, and the tilt piston 32b tilts forward and backward.

  As described above, in the forklift according to the present embodiment, the hydraulic oil in the oil tank T is constantly fed through the oil pump P. When only one of the lift lever LE and the tilt lever LT is operated, the shut valve 36 is located at the communication position, and the hydraulic oil passage is maintained in the communication state, so that the lift operation or the forward / backward tilt operation is performed. Only one of these is allowed to operate independently.

  On the other hand, when both the lift lever LE and the tilt lever LT are operated simultaneously from the state shown in FIG. 2 as shown in FIG. 2C, the contacts of the lift side proximity switch 39 and the tilt side proximity switch 40 are closed. Thus, when the relay circuit 41 is energized, the coil 41b is excited. Then, the normally open contact 41a of the relay circuit 41 is closed, and the solenoid 38 of the shut valve 36 is energized. Therefore, the shut valve 36 is switched from the communication position to the shut-off position, and the hydraulic oil from the oil pump P cannot be supplied to the pilot valves 25a and 35a. Therefore, in the forklift, the valve position in the lift control valve 25 and the valve position in the tilt control valve 35 cannot be controlled by cutting off the supply of hydraulic oil to the pilot valves 25a, 35a. As a result, both the lifting piston 22b and the tilt piston 32b are inoperable.

  As described above, in the forklift according to the present embodiment, when both the lift lever LE and the tilt lever LT are operated simultaneously, the shut valve 36 exists at the shut-off position to shut off the hydraulic oil passage, Prohibit (limit) simultaneous tilt movement. In the present embodiment, the shut-off valve 36, the lift side proximity switch 39, the tilt side proximity switch 40, and the relay circuit 41 constitute a simultaneous operation limiting mechanism.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The forklift according to the present embodiment is equipped with a simultaneous operation restriction mechanism, so that the simultaneous lifting / lowering operation based on the simultaneous operation of the lifting lever LE and the tilt lever LT is restricted. Therefore, in a forklift, even if you forget to unlock the container lock device and lift the freight car together with the container without restricting the operation sequence, it can be easily lowered without returning to the rails. be able to.

  (2) Conventionally, when a container is derailed, it has to affect the train schedule and bring a vehicle such as a crane truck to the restoration work, and there has been a risk of a great loss of time and cost. However, by providing a forklift with a simultaneous operation restriction mechanism, it is possible to suppress loss.

  (3) In the present embodiment, a simultaneous operation restriction mechanism including the proximity switches 39 and 40, the shut valve 36, and the relay circuit 41 is added to the hydraulic mechanism that operates the lift cylinder 22 and the tilt cylinder 32, and the lift lever LE. And simultaneous operation of the tilt lever LT. Therefore, it is possible to equip not only the vehicle before the sale but also the vehicle after the sale with a simultaneous operation restriction mechanism without making a significant design change.

  (4) Further, since the simultaneous operation limiting mechanism of the present embodiment is configured to block the oil passage of the hydraulic mechanism, these mechanisms are compared with the case where the lifting lever LE and the tilt lever LT are mechanically locked. Even if the configuration of each of the levers LE, LT, etc. differs depending on the vehicle type of the forklift, it can be easily applied.

  (5) Since the energization state of the shut valve 36 is controlled using the proximity switches 39 and 40 and the relay circuit 41, the simultaneous operation limiting mechanism can be realized with a simple configuration. In this embodiment, by connecting the proximity switches 39 and 40 in series, the shut valve 36 can be controlled using a single relay circuit 41, and the simultaneous operation limiting mechanism can be realized with a simpler configuration. .

(Second Embodiment)
The second embodiment embodying the present invention will be described below. In the embodiments described below, the same components as those in the embodiments already described are denoted by the same reference numerals, and the redundant description thereof is omitted or simplified.

  In this embodiment, the configuration of the proximity switch group and the relay circuit is different from that of the first embodiment. For this reason, in the following description, it demonstrates centering on the structure of the proximity switch group and relay circuit which are different from 1st Embodiment.

  The proximity switch group according to the present embodiment includes a lift side proximity switch 39 and a tilt side proximity switch 40 as in the first embodiment. Since the configuration (function, arrangement, etc.) of each of these switches 39 and 40 is the same as that of the first embodiment, a duplicate description thereof is omitted. In this embodiment, the lift side proximity switch 39 and the tilt side proximity switch 40 are directly connected to the relay circuit, and the levers LE and LT are operated so that the contacts of the switches 39 and 40 can be closed. Each voltage is output to the relay circuit.

  In the present embodiment, the relay circuit includes a plurality (three) of a relay circuit 42 as a first relay circuit, a relay circuit 43 as a second relay circuit, and a relay circuit 44 as a third relay circuit. Has been. The relay circuit 42 includes a normally open contact (a contact) 42a and a coil (electromagnet) 42b whose one terminal is connected in series to the contact of the lift side proximity switch 39, and the other terminal of the coil 42b is grounded. Has been.

  The relay circuit 43 includes a normally open contact (a contact) 43a and a coil (electromagnet) 43b whose one terminal is connected in series to the contact of the tilt side proximity switch 40, and the other terminal of the coil 43b is grounded. Has been. One terminal of the normally open contact 43a is connected to the power source and the other terminal is connected to one terminal of the normally open contact 42a of the relay circuit 42. The normally open contact 43a is connected to the normally open contact 42a. They are connected in series. The relay circuit 44 includes a normally closed contact (b contact) 44a and a coil (electromagnet) 44b whose one terminal is connected in series to the contact of the normally open contact 42a of the relay circuit 42, and the other of the coil 44b. The terminal is grounded. One terminal of the normally closed contact 44 a is connected to the power source, and the other terminal is connected to the solenoid 38 of the shut valve 36. The normally open contact 42a is switched from the open state to the closed state when the coil 42b is excited, and the normally open contact 43a is switched from the open state to the closed state when the coil 43b is excited. The normally closed contact 44a is switched from the closed state to the open state when the coil 44b is excited. Therefore, in the relay circuit of this embodiment, the solenoid 38 of the shut valve 36 is energized when no voltage is applied to the coil 44b of the relay circuit 44 and the normally closed contact 44a is kept closed, and the shut valve 36 is energized. Is arranged at the communication position (state of FIG. 1). On the other hand, in the relay circuit of this embodiment, when a voltage is applied to the coil 44b of the relay circuit 44 and the normally closed contact 44a is opened, the solenoid 38 of the shut valve 36 is de-energized, and the shut valve 36 is Arranged in the blocking position.

  Hereinafter, the operation of the forklift according to the present embodiment will be described with reference to FIGS. 3 and 4A, 4B, and 4C. In the following description, the description will focus on an aspect in which the simultaneous operation of the fork 24 ascending / descending operation and the mast 20 tilting operation based on the simultaneous operation of the elevating lever LE and the tilt lever LT is prohibited (restricted).

  When both the lift lever LE and the tilt lever LT are in the neutral position (when neither of them is operated), the contacts of the lift side proximity switch 39 and the tilt side proximity switch 40 are in an open state (OFF state). ing. For this reason, as shown in FIG. 1, the relay circuits 42 and 43 are not energized, and the coils 42b and 43b are demagnetized, so that the normally open contacts 42a and 43a are kept open. In addition, the coil 44b is demagnetized without energizing the relay circuit 44, so that the normally closed contact 44a is kept closed. As a result, the shut valve 36 exists in the communication position, and the hydraulic oil from the oil pump P can be supplied to the pilot valves 25a and 35a.

  If only the lift lever LE is operated from the state shown in FIG. 3 as shown in FIG. 4A, the contact of the lift side proximity switch 39 is closed and the coil 42b of the relay circuit 42 is excited and normally opened. The contact 42a is closed. However, since the normally open contact 43a of the relay circuit 43 is kept open, the coil 44b of the relay circuit 44 is not excited and the normally closed contact 44a is kept closed. As a result, the solenoid 38 of the shut valve 36 remains energized. For this reason, the shut valve 36 exists in the communication position, and the hydraulic oil from the oil pump P can be supplied to the pilot valves 25a and 35a. Therefore, in the forklift, the valve position in the lift control valve 25 is controlled by the pilot valve 25a based on the operation position of the lift lever LE, and the lift piston 22b moves up and down.

  When only the tilt lever LT is operated from the state shown in FIG. 3 as shown in FIG. 4B, the contact of the tilt side proximity switch 40 is closed and the coil 43b of the relay circuit 43 is excited and normally opened. The contact 43a is closed. However, since the normally open contact 42a of the relay circuit 42 is kept open, the coil 44b of the relay circuit 44 is not excited and the normally closed contact 44a is kept closed. As a result, the solenoid 38 of the shut valve 36 remains energized. For this reason, the shut valve 36 exists in the communicating position, and the hydraulic oil from the oil pump P can be supplied to the pilot valves 25a and 35a, respectively. Therefore, in the forklift, the valve position in the tilt control valve 35 is controlled by the pilot valve 35a based on the operation position of the tilt lever LT, and the tilt piston 32b tilts forward and backward.

  As described above, in the forklift according to the present embodiment, the hydraulic oil in the oil tank T is constantly fed through the oil pump P. When only one of the lift lever LE and the tilt lever LT is operated, the shut valve 36 is located at the communication position, and the hydraulic oil passage is maintained in the communication state, so that the lift operation or the forward / backward tilt operation is performed. Only one of these is allowed to operate independently.

  On the other hand, when both the lift lever LE and the tilt lever LT are simultaneously operated from the state shown in FIG. 3 as shown in FIG. 4C, the contacts of the lift side proximity switch 39 and the tilt side proximity switch 40 are closed. It becomes. Then, the coils 42b and 43b of the relay circuits 42 and 43 are excited, and the normally open contacts 42a and 43a are closed. As a result, the coil 44b of the relay circuit 44 is excited, the normally closed contact 44a is opened, and the solenoid 38 of the shut valve 36 is de-energized. Therefore, the shut valve 36 is switched from the communication position to the shut-off position, and the hydraulic oil from the oil pump P cannot be supplied to the pilot valves 25a and 35a. Therefore, in the forklift, the valve position in the lift control valve 25 and the valve position in the tilt control valve 35 cannot be controlled by cutting off the supply of hydraulic oil to the pilot valves 25a, 35a. As a result, both the lifting piston 22b and the tilt piston 32b are inoperable.

  As described above, in the forklift according to the present embodiment, when both the lift lever LE and the tilt lever LT are operated simultaneously, the shut valve 36 exists at the shut-off position to shut off the hydraulic oil passage, Prohibit (limit) simultaneous tilt movement. In the present embodiment, the shut-off valve 36, the lift side proximity switch 39, the tilt side proximity switch 40, and the relay circuits 42 to 44 constitute a simultaneous operation limiting mechanism. According to this embodiment, the same effects as the effects (1) to (4) of the first embodiment can be obtained.

In addition, you may change each said embodiment as follows.
In the second embodiment, the relay circuit may be constituted by the relay circuit 42 and the relay circuit 43, and the solenoid 38 of the shut valve 36 may be connected to the normally open contact 42 a of the relay circuit 42. In this case, the shut valve 36 is configured to switch from the communication position to the blocking position when the solenoid 38 is energized. In this configuration, when the switches 39 and 40 detect the operation of the levers LT and LE, the normally open contacts 42a and 43a of the relay circuits 42 and 43 are closed and the solenoid 38 is energized.

  In the first embodiment, the normally open contact 41a constituting the relay circuit 41 may be replaced with a normally closed contact. In this case, the shut valve 36 is configured to exist in the communication position when the solenoid 38 is energized, and to switch from the communication position to the blocking position when the solenoid 38 is de-energized.

  In the second embodiment, the normally closed contact 44a constituting the relay circuit 44 may be replaced with a normally open contact. In this case, the shut valve 36 is configured to switch from the communication position to the blocking position when the solenoid 38 is energized, and to be in the communication position when the solenoid 38 is de-energized.

  In each embodiment, the detection switch for detecting the operation state of the elevating lever LE and the tilt lever LT may be changed to another switch (including a sensor) instead of the non-contact type proximity switch. For example, a contact type detection switch may be used.

  In each embodiment, each lever LT, LE is directly connected to each pilot valve 25a, 35a, and the valve position of each control valve 25, 35 is controlled by each pilot valve 25a, 35a. The valve position may be controlled by directly connecting the levers LT and LE to 35.

The block diagram which shows the hydraulic mechanism and the simultaneous operation | movement restriction mechanism in 1st Embodiment. (A)-(c) is a schematic diagram explaining operation | movement of the simultaneous operation | movement restriction | limiting mechanism in 1st Embodiment. The block diagram which shows the hydraulic mechanism and the simultaneous operation | movement restriction mechanism in 2nd Embodiment. (A)-(c) is a schematic diagram explaining operation | movement of the simultaneous operation | movement restriction | limiting mechanism in 2nd Embodiment. (A), (b) is a schematic diagram explaining the operation | work which moves the container mounted in the freight car with the forklift.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Mast, 22 ... Elevating cylinder, 24 ... Fork, 32 ... Tilt cylinder, 36 ... Shut valve, 39 ... Elevating side proximity switch, 40 ... Tilt side proximity switch, 41 ... Relay circuit, H1-H11 ... Piping, LE ... Lift lever, LT ... tilt lever.

Claims (5)

Lifting device for lifting and lowering the cargo handling equipment provided on the mast by hydraulic pressure, lifting and lowering operating means for operating the lifting device, tilting device for tilting the mast by hydraulic pressure, and operating the tilting device A simultaneous operation limiting mechanism that is mounted on a vehicle including a tilting operation means that operates simultaneously, and that restricts simultaneous operation of the lifting device and the tilting device by simultaneously operating the lifting operation unit and the tilting operation unit. There,
A detection switch for detecting an operation state of the lifting operation means and an operation state of the tilt operation means;
An electromagnetic switching valve disposed on an oil passage for supplying hydraulic oil to the elevating device and the tilting device, and switching between a shut-off state for shutting off the oil passage and a communication state for communicating the oil passage;
The electromagnetic switching valve is connected between the detection switch and the electromagnetic switching valve and energizes the electromagnetic switching valve so as to switch the oil passage from the communication state to the cutoff state and from the cutoff state to the communication state based on the detection state of the detection switch. An electrical circuit for controlling the state,
The electrical circuit controls an energization state of the electromagnetic switching valve so that the oil passage is switched from a communication state to a cutoff state when the elevating operation means and the tilting operation means are operated simultaneously. A simultaneous operation restriction mechanism. The detection switch includes a first switch that detects an operation state of the elevating operation means and a second switch that detects an operation state of the tilt operation means. The first switch and the second switch Are connected in series,
The electric circuit has a normally open contact connected to the electromagnetic switching valve and a coil connected in series to each switch, or a normally closed contact connected to the electromagnetic switching valve and a coil connected in series to each switch. A single relay circuit,
The relay circuit is energized when the first switch detects an operation of the elevating operation means and the second switch detects an operation of the tilt operation means,
When the relay circuit has a normally open contact, the electromagnetic switching valve is energized when the normally open contact can be closed by excitation of the coil, and switches the oil passage from the communication state to the cutoff state. On the other hand, when the relay circuit has a normally closed contact, the normally closed contact can be opened by excitation of the coil, so that the energized state is de-energized, and the oil passage is switched from the communication state to the cutoff state. The simultaneous operation limiting mechanism according to claim 1. The detection switch includes a first switch for detecting an operation state of the lifting operation means and a second switch for detecting an operation state of the tilt operation means,
The electrical circuit includes: a first relay circuit having a normally open contact and a coil connected in series to the first switch; a normally open contact connected in series to a normally open contact of the first relay circuit; A second relay circuit having a coil connected in series to the second switch; a normally open contact or a normally closed contact connected to the electromagnetic switching valve; and a coil connected in series to the normally open contact of each switch. A third relay circuit having
The third relay circuit is energized when the first switch detects an operation of the elevating operation means and the second switch detects an operation of the tilt operation means,
When the third relay circuit has a normally open contact, the electromagnetic switching valve is energized when the normally open contact can be closed by excitation of the coil, and the oil passage is disconnected from the communication state. On the other hand, when the third relay circuit has a normally closed contact, the normally closed contact can be opened by excitation of the coil, thereby de-energizing the oil path from the communication state. The simultaneous operation limiting mechanism according to claim 1, wherein the simultaneous operation limiting mechanism is switched to a cutoff state. The detection switch includes a first switch for detecting an operation state of the lifting operation means and a second switch for detecting an operation state of the tilt operation means,
The electrical circuit includes a first relay circuit having a normally open contact and a coil connected in series to the first switch; and the electromagnetic switching valve connected in series to the normally open contact of the first relay circuit. A second relay circuit having a normally open contact connected to the second switch and a coil connected in series to the second switch,
2. The simultaneous operation limiting mechanism according to claim 1, wherein the electromagnetic switching valve is energized when both coils of the relay circuit are excited to switch the oil passage from a communication state to a cutoff state. A forklift equipped with the simultaneous operation restriction mechanism according to any one of claims 1 to 4.

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