JP2023163883A - Dump truck - Google Patents

Abstract

To enable continuation of slide operation of a load-carrying platform even under a condition of high load on a dump frame.SOLUTION: A dump truck 1 comprises: a chassis frame 10; a dump frame 20; a cylinder 50 comprising a rod 51 telescopic in a cross direction and turning; a load-carrying platform 30 moving in a cross direction and turning according to telescopic motion of the rod 51; a lock device 60 capable of fixing the dump frame 20 in such a state as landing on the chassis frame 10; and a first sensor 70 provided near the lock device 60 and detecting fixation of the dump frame 20 by the lock device 60, or landing of the dump frame 20 on the chassis frame 10. The dump truck 1 approves of the telescopic operation of the cylinder 50 in the prescribed cases including detection of fixation or landing of the dump frame 20 by the first sensor 70.SELECTED DRAWING: Figure 2

Description

The present invention relates to a dump truck.

BACKGROUND ART Dump trucks that can transport earth and sand and transport construction vehicles have been known for a long time. For example, Patent Document 1 describes a swing frame (dump frame) arranged on the vehicle body that swings around a first pivot, a slide cylinder that expands and contracts and rotates around a second pivot, and a slide cylinder that extends and contracts and rotates around a second pivot. A transportation vehicle is disclosed that includes a loading platform that is disposed in a storage area, moves in the front and rear directions as the slide cylinder expands and contracts, and rotates together with the slide cylinder. In the transport vehicle disclosed in Patent Document 1, when the slide cylinder is extended and the loading platform is moved rearward, the slide cylinder and the loading platform are rotated backward and downward. This allows the loading platform to touch the ground, allowing the construction vehicle to get onto the loading platform.

The transport vehicle disclosed in Patent Document 1 engages the swinging frame and the vehicle body so as to prevent the swinging frame from lifting off from the vehicle body when the loading platform is retracted beyond the forward limit, and when the loading platform is at the forward limit. It is equipped with an anti-lifting mechanism that releases the engagement between the swing frame and the vehicle body at certain times. This prevents the swing frame from being pulled by the loading platform and dumping when the loading platform is moved backward. Further, the transport vehicle disclosed in Patent Document 1 includes a landing sensor that can detect that the swing frame is in a prone position on the vehicle body. The transport vehicle disclosed in Patent Document 1 is configured such that the loading platform cannot be slid and lowered onto the ground unless the landing sensor detects that the swing frame is lying down.

JP2020-55438A

According to the findings of the inventor of the present application, for example, when a loaded platform of a dump truck as described in Patent Document 1 is moved backward, the platform receives a force that tends to tilt, causing the dump frame to warp. There is. One of the reasons why the dump frame warps is that the dump frame is fixed to the chassis frame by a locking device (in Patent Document 1, an anti-lifting mechanism). If the dump frame is fixed to the chassis frame, the dump frame will not dump even if the loading platform is subjected to a force that tends to tilt, but instead may warp as described above. Such warpage of the dump frame may occur, for example, when a construction vehicle is placed on the back of the loading platform.

According to the inventor's further findings, when the dump frame warps due to such a high load, the dump frame moves out of the detection range of the sensor that detects that the dump frame is landing on the chassis frame, and the sensor There is a possibility that the landing of the dump frame will not be detected. For example, when such non-detection occurs in the transport vehicle disclosed in Patent Document 1, an error occurs and the work of sliding the cargo platform and lowering it onto the ground is stopped.

The present invention has been made in view of the above, and an object of the present invention is to provide a dump truck in which the sliding movement of the loading platform can be easily continued even when the load applied to the dump frame is large.

The dump truck disclosed herein includes a chassis frame extending in the front-rear direction, a first rotating shaft supported by the chassis frame and extending in the vehicle width direction, and a first rotating shaft disposed on the chassis frame and rotating around the first rotating shaft. a dump frame that rotates; a second rotation shaft that is supported by the dump frame and extends in the vehicle width direction; a cylinder that includes a rod that is extendable and retractable in the front-rear direction and rotates around the second rotation shaft; a loading platform that is connected to the chassis frame and moves in the front-rear direction according to the expansion and contraction of the rod and rotates together with the cylinder around the second rotation axis; a locking device capable of fixing a front end portion of the chassis frame to the chassis frame; and a locking device provided near the locking device, the locking device fixing the dump frame, or the dump frame attached to the chassis frame. a first sensor that detects whether the cylinder is on the floor; an operating end capable of expanding and contracting the cylinder; and a control device connected to the first sensor and the operating end and controlling the cylinder; Equipped with The control device allows the operation end to extend and retract the cylinder in a predetermined case including when the first sensor detects that the dump frame is fixed or landed on the floor.

According to the dump truck, the first sensor detects that the dump frame is fixed by the lock device, or detects that the dump frame is placed on the chassis frame near the lock device. . When the first sensor detects fixation of the locking device, the detection by the first sensor is not affected by the warpage of the dump frame. Even when the first sensor detects landing of the dump frame on the floor, since the first sensor is provided near the locking device, the detection by the first sensor is less susceptible to warping of the dump frame. Therefore, according to the dump truck, the sliding movement of the loading platform can often be continued even in situations where a large load is applied to the dump frame.

According to a preferred aspect of the dump truck of the present invention, the dump truck further includes a second sensor that detects that the dump frame is placed on the chassis frame. The second sensor is provided behind the first sensor. The first sensor is configured to detect that the locking device is fixing the dump frame.

According to the dump truck, the first sensor detects fixation of the dump frame by the locking device, and the second sensor detects landing of the dump frame on the floor, which is not directly detected by the first sensor. Therefore, according to the dump truck, landing of the dump frame on the floor can be detected more reliably.

According to a preferred aspect of the dump truck, the control device is configured such that the first sensor detects fixation of the dump frame, and the second sensor detects landing of the dump frame on the floor. In a predetermined case including at least one of the following, expansion/contraction operation of the cylinder by the operating end is permitted.

According to the dump truck, even if either one of the first sensor detecting that the dump frame is fixed and the second sensor detecting that the dump frame has landed on the floor, the cylinder expands and contracts. Operation is allowed. Therefore, according to the dump truck, the sliding operation of the loading platform can be continued more easily.

According to a preferable aspect of the dump truck, the locking device releases the fixation of the dump frame when the loading platform is located in front of the predetermined position, and the locking device releases the fixation of the dump frame when the loading platform is located in front of the predetermined position. The dump frame is configured to be fixed when in position.

According to the above aspect, when the loading platform is located ahead of the predetermined position, the dump frame is released from being fixed so that the loading platform can be dumped. Therefore, when the loading platform is located ahead of the predetermined position, the first sensor does not detect fixation of the dump frame by the locking device. However, during that time, based on the detection of landing of the dump frame on the floor by the second sensor, the operation end is allowed to extend and contract the cylinder, and thereby the loading platform can be slid.

According to a preferable aspect of the dump truck, the locking device has a locking position in which it engages with the dump frame and the chassis frame when the locking device is placed on the chassis frame, and a locking position in which the locking device engages with the dump frame in a state where it is placed on the chassis frame, and a locking position in which the locking device is separated from the chassis frame or the dump frame. The locking member includes an engaging member that moves to an unlock position. The dump truck further includes an unlocking member connected to the loading platform. The lock release member comes into contact with the engagement member and pushes the engagement member to the unlock position when the loading platform is located in front of the predetermined position.

According to the above aspect, by positioning the loading platform ahead of the predetermined position, the lock release member comes into contact with the engagement member, and the fixation of the dump frame by the lock device can be released without any particular control.

According to a preferable aspect of the aspect in which the first sensor detects that the locking device is fixing the dump frame, the locking device is configured to lock the dump frame and the chassis frame in a state where the locking device is fixed to the chassis frame. and an engagement member that moves between a locked position where it engages with the chassis frame and an unlocked position where it separates from the chassis frame or the dump frame. The first sensor detects that the locking device is fixing the dump frame by detecting that the engaging member is located at the locking position.

According to the above aspect, by detecting the position of the engaging member with the first sensor, it is possible to reliably detect that the locking device is fixing the dump frame.

According to the dump truck according to the present invention, it is easy to continue the sliding operation of the loading platform even in a situation where a large load is applied to the dump frame.

FIG. 2 is a side view of a loader dump according to one embodiment. FIG. 3 is a side view of the loader dump during a dumping operation and a sliding operation. It is a top view of a dump frame and a guide frame. It is a side view of a dump frame and a guide frame. FIG. 3 is a side view of the locking device in a locked state. FIG. 3 is a side view of the locking device in an unlocked state. It is a control block diagram of a slide cylinder. It is a flowchart concerning sliding operation of a loading platform. It is a side view of the loader dump which is a schematic diagram showing the warpage of the dump frame.

[Loader dump configuration]
Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In addition, when describing a plurality of embodiments, the same reference numerals are given to members and parts that have the same effect, and overlapping explanations are omitted or simplified as appropriate.

FIG. 1 is a side view of a loader dump 1 according to an embodiment. As shown in FIG. 1, the loader dump 1 according to the present embodiment includes a chassis frame 10 extending in the front-rear direction, a cab 5 supported by the chassis frame 10, and a cab 5 arranged on the chassis frame 10 and rotating in the vertical direction. The dump frame 20 includes a dump frame 20, and a loading platform 30 disposed on the dump frame 20. The chassis frame 10 is supported by a front wheel 3F and a rear wheel 3B. A driver's seat (not shown) is provided inside the cab 5. In the following explanation, unless otherwise specified, front, rear, left, right, top, and bottom mean the front, back, left, right, top, and bottom as seen from the driver sitting in the driver's seat. shall be.

FIG. 2 is a side view of the loader dump 1 during a dumping operation and a sliding operation. As shown in FIG. 2, the loader dump 1 is capable of a dump operation in which the loading platform 30 is tilted. The loader dump 1 includes a first rotation shaft 15 that is a rotation shaft of the dump frame 20. The first rotation shaft 15 is provided in the chassis frame 10 and extends in the vehicle width direction. Here, the first rotation shaft 15 is provided at the rear end of the chassis frame 10. The first rotation shaft 15 may be indirectly supported by the chassis frame 10 via another member. The dump frame 20 is arranged on the chassis frame 10 and rotates around the first rotation axis 15. The dump frame 20 is engaged with the first rotation shaft 15 via a dump hinge 21 so as to be rotatable in the vertical direction.

The front portion of the dump frame 20 is lifted by a hoist mechanism (not shown), and the dump frame 20 is tilted by rotating around the first rotation axis 15. The hoist mechanism includes, for example, a lift arm and a hydraulic cylinder. When the hydraulic cylinder is contracted, the dump frame 20 is in a horizontal state, and the loading platform 30 maintains a horizontal posture. On the other hand, when the hydraulic cylinder extends, the front portion of the dump frame 20 is lifted, and the dump frame 20 rotates around the first rotation axis 15. As a result, the dump frame 20 and the loading platform 30 are tilted backward. Hereinafter, this state will also be referred to as a dump state. In the drawings below, a state in which the loading platform 30 is not tilted is indicated by a symbol S1, and a dumped state is indicated by a symbol S2.

As shown in FIG. 2, the loader dump 1 is capable of sliding the loading platform 30 along the dump frame 20. When the loading platform 30 is slid rearward to cause a portion to protrude rearward beyond the dump frame 20, the loading platform 30 rotates backward due to the weight of the protruding portion. As shown in FIG. 2, the loader dump 1 includes a second rotation shaft 25 provided on a dump frame 20 and extending in the vehicle width direction, and a guide frame 40 and a slide cylinder 50 that rotate around the second rotation shaft 25. , is equipped with.

FIG. 3 is a plan view of the dump frame 20 and the guide frame 40. FIG. 4 is a side view of the dump frame 20 and the guide frame 40. As shown in FIGS. 3 and 4, the dump frame 20 has a substantially rectangular frame shape when viewed from above, and extends in the front-rear direction. The second rotation shaft 25 is provided at the rear end of the dump frame 20. The second rotation shaft 25 as a rotation axis of the slide cylinder 50 may be shared with the first rotation shaft 15. However, the position of the second rotation shaft 25 with respect to the dump frame 20 needs to remain unchanged, and it is necessary that the second rotation shaft 25 is substantially provided on the dump frame 20. As shown in FIG. 3, the dump frame 20 includes a sensor mounting plate 22 to which a landing sensor 75 (see FIG. 1), which will be described later, is attached. The landing sensor 75 is a sensor that detects that the dump frame 20 is landing on the chassis frame 10. The sensor mounting plate 22 is provided at the center of the dump frame 20 in the front-rear direction.

As shown in FIGS. 3 and 4, the guide frame 40 includes a front frame 40F that is provided in front of the second rotation shaft 25 and fixed to the dump frame 20, and a front frame 40F that is fixed to the dump frame 20 and rearward of the second rotation shaft 25. A rear frame 40Rr is provided and rotates around the second rotation axis 25. The front frame 40F includes a pair of left and right guide portions 41 that extend in the front-rear direction. The guide portion 41 has a substantially U-shaped cross-section. The loading platform 30 includes a roller (not shown) that rolls inside the U-shape of the guide portion 41 . As the rollers roll within the guide portion 41, the loading platform 30 is movable in the front-rear direction along the guide frame 40. As shown in FIG. 4, the guide portion 41 includes an inclined portion 41a that slopes upward toward the rear at the front portion.

The rear frame 40Rr projects further rearward than the dump frame 20. The rear frame 40Rr engages with the second rotation shaft 25 so as to be rotatable in the vertical direction. The rear frame 40Rr includes rollers (not shown) on which the loading platform 30 rides, before and after the second rotation shaft 25. When the loading platform 30 starts to move backward, the front side lifts up along the inclined portion 41a, and begins to rotate backward together with the rear frame 40Rr. The loading platform 30 is supported by rollers (not shown) on the rear frame 40Rr.

The slide cylinder 50 is supported by the rear frame 40Rr of the guide frame 40, and rotates around the second rotation axis 25 together with the rear frame 40Rr. The slide cylinder 50 is, for example, a hydraulic cylinder. As shown in FIG. 1, the slide cylinder 50 includes a rod 51 that is extendable and retractable in the front-rear direction, and a tube 52 that accommodates the rod 51. The rear end portion of the tube 52 is supported by the rear frame 40Rr so as to be swingable in the vertical direction. However, the tube 52 may be fixed to the rear frame 40Rr so as not to be able to swing. Alternatively, the tube 52 may be directly and rotatably supported by the second rotation shaft 25. The rear end portion of the rod 51 is connected to the bottom plate 31 of the loading platform 30 so as to be swingable in the vertical direction.

The loading platform 30 is connected to a rod 51 of a slide cylinder 50, and moves in the front-back direction as the rod 51 expands and contracts. The loading platform 30 also rotates around the second rotation axis 25 together with the slide cylinder 50. Here, the loading platform 30 moves in the front-rear direction along the guide frame 40 and rotates together with the rear frame 40Rr of the guide frame 40 and the slide cylinder 50. As shown in FIG. 2, when the loading platform 30 is completely lowered, the rear end of the loading platform 30 touches the ground. Hereinafter, this state will also be referred to as a grounding state, and will be represented by the reference numeral S3 in the drawings.

As shown in FIG. 1, the loading platform 30 includes a bottom plate 31, a pair of left and right side plates 32, and a tailgate 33 forming a rear wall. The tailgate 33 is rotatably supported by an upper hinge shaft 34 provided at the upper end of the tailgate 33 and rotatably supported by a lower hinge shaft 35 provided at the lower end of the tailgate 33. ing. When discharging dirt, by making the tailgate 33 rotatable around the upper hinge shaft 34, the dirt in the loading platform 30 can be discharged to the ground as the loading platform 30 inclines. When loading or unloading a construction vehicle, the cargo platform 30 is brought into contact with the ground, and the tailgate 33 is brought into contact with the ground by rotating the tailgate 33 rearward around the lower hinge shaft 35. Thereby, the construction vehicle can be loaded onto the loading platform 30, or the construction vehicle can be unloaded from the loading platform 30.

The loader dump 1 includes a locking device 60 that can fix the dump frame 20 in a state where it is placed on the chassis frame 10, a lock sensor 70 that detects that the dump frame 20 is fixed by the locking device 60, and a dump frame 20. a landing sensor 75 for detecting that the vehicle has landed on the chassis frame 10.

As shown in FIG. 1, the locking device 60 is provided ahead of the first rotation shaft 15. Here, the locking device 60 fixes the front end of the dump frame 20 and the chassis frame 10 in a state where the dump frame 20 is placed on the chassis frame 10. Here, the “front end portion of the dump frame 20” refers to, for example, a portion within one-third of the front side of the dump frame 20. Furthermore, "fixed" means that the dump frame 20 is substantially unrotatable, and includes a state in which it can move due to slight play or the like. Hereinafter, the state in which the locking device 60 fixes the dump frame 20 is also referred to as a locked state, and the state in which the locking device 60 frees the dump frame 20 is also referred to as an unlocked state.

FIG. 5 is a side view of the lock device 60 in the locked state. FIG. 6 is a side view of the lock device 60 in the unlocked state. As shown in FIG. 5, in this embodiment, the lock device 60 is provided on the side surface of the dump frame 20. However, the lock device 60 may be provided on the chassis frame 10 side. The locking device 60 includes a hook 61 that is locked to the shaft 11 of the chassis frame 10, a rotating shaft 62 of the hook 61, a spring 63 stretched between the hook 61 and the dump frame 20, and a lock sensor 70. A detection plate 64 for detection is provided. As shown in FIG. 5, the shaft 11 of the chassis frame 10 is a cylindrical member extending in the vehicle width direction.

The hook 61 is an example of an engagement member that engages with the chassis frame 10 and the dump frame 20. Here, the hook 61 is constantly engaged with the dump frame 20 via the rotating shaft 62. The hook 61 has two positions: a locked position (position shown in FIG. 5) in which the hook 61 engages with the dump frame 20 and the chassis frame 10 in a state where it is placed on the chassis frame 10, and an unlocked position (position shown in FIG. 6) in which it is separated from the chassis frame 10. ) and move to. Note that when the locking device 60 is provided on the side of the chassis frame 10, the hook 61 may be separated from the dump frame 20 in the unlocked position.

The rotation shaft 62 is provided on the side surface of the dump frame 20 and extends in the vehicle width direction. The hook 61 is rotatable around a rotation axis 62. The hook 61 has an upper portion 61U located above the rotation shaft 62 and a lower portion 61D located below the rotation shaft 62. A hook portion 61a into which the shaft 11 of the chassis frame 10 is inserted is formed in the lower portion 61D of the hook 61. The upper portion 61U of the hook 61 is formed with a spring locking portion 61b to which one end of the spring 63 is locked. The other end of the spring 63 is locked to the side surface of the dump frame 20. The spring 63 is stretched between the hook 61 and the dump frame 20 in a stretched state. The restoring force of the spring 63 generates a rotational force on the hook 61, and this rotational force holds the hook 61 in the locked position as shown in FIG.

A detection plate 64 that is detected by a lock sensor 70 is attached to the lower end of the hook 61. However, what is detected by the lock sensor 70 may be the hook 61 itself. The lock sensor 70 is provided closer to the lock device 60 than the landing sensor 75 is. Here, the lock sensor 70 is provided on the side of the detection plate 64 when the hook 61 is in the lock position (in FIG. 5, the lock sensor 70 and the detection plate 64 are lined up in the depth direction of the page). ). The lock sensor 70 is, for example, a proximity sensor. However, the type of lock sensor 70 is not particularly limited. As shown in FIG. 5, when the lock device 60 is in the locked state, the detection plate 64 approaches the lock sensor 70 and is detected by the lock sensor 70. The lock sensor 70 detects that the lock device 60 is fixing the dump frame 20 by detecting that the hook 61 is located at the lock position.

As shown in FIG. 6, the locking device 60 is configured to unlock the dump frame 20 when the loading platform 30 is located ahead of a predetermined position. This is to enable the dump frame 20 to be dumped. The predetermined position of the loading platform 30 is the foremost position of the movable range of the loading platform 30 here. However, the predetermined position of the loading platform 30 is not limited as long as it is a position where there is no problem even if the loading platform 30 is dumped. The locking device 60 fixes the dump frame 20 when the loading platform 30 is located at the rear of the predetermined position (here, the frontmost position).

As shown in FIG. 6, the loader dump 1 includes a lock release plate 36 that abuts the hook 61 and pushes the hook 61 to the unlocked position when the loading platform 30 is located ahead of a predetermined position. The lock release plate 36 is connected to the side surface of the loading platform 30 and moves in the front-rear direction together with the loading platform 30. As shown in FIG. 6, when the loading platform 30 moves to the frontmost position, the lock release plate 36 pushes the upper portion 61U of the hook 61 forward. As a result, the upper portion 61U of the hook 61 is rotated forward against the biasing force of the spring 63. As a result, the hook portion 61a of the lower portion 61D moves rearward and comes off the shaft 11 of the chassis frame 10. Therefore, the dump frame 20 is in an unlocked state.

As shown in FIG. 6, when the dump frame 20 is in the unlocked state, the detection plate 64 moves from the vicinity of the lock sensor 70. Therefore, the lock sensor 70 cannot detect the detection plate 64. The lock sensor 70 thereby detects whether the lock device 60 is fixing the dump frame 20.

The landing sensor 75 is attached to the sensor mounting plate 22 of the dump frame 20. FIG. 1 shows the position of the landing sensor 75. As shown in FIG. 1, the landing sensor 75 is provided behind the lock sensor 70. Here, the landing sensor 75 is arranged at the center of the dump frame 20 in the front-rear direction. Landing sensor 75 is, for example, a proximity sensor. However, the type of landing sensor 75 is not limited. The landing sensor 75 may be, for example, a contact type sensor including a movable part that is pushed by the chassis frame 10. The landing sensor 75 is located near the chassis frame 10 and detects the chassis frame 10 when the dump frame 20 is placed on the chassis frame 10. When the dump frame 20 dumps, the floor landing sensor 75 moves away from the chassis frame 10 and becomes unable to detect the chassis frame 10. The landing sensor 75 thereby detects whether the dump frame 20 has landed on the chassis frame 10 or not. Note that the landing sensor 75 may be provided on the chassis frame 10 to detect the dump frame 20.

FIG. 7 is a control block diagram of the slide cylinder 50. The slide cylinder 50 is controlled, for example, by controlling oil pressure by a solenoid valve driven by a control circuit, but in FIG. 7, the slide cylinder 50 is illustrated as being directly controlled by the control circuit 85. As shown in FIG. 7, the loader dump 1 includes an operation switch 80 that can extend and retract the slide cylinder 50, and a control circuit 85 that controls the slide cylinder 50 via, for example, a hydraulic system. . The operation switch 80 is provided inside the cab 5, for example. The control circuit 85 is connected to the lock sensor 70, landing sensor 75, and operation switch 80. Note that what is connected to the lock sensor 70, landing sensor 75, and operation switch 80 to control the slide cylinder 50 does not have to be an actual wired circuit, but may be a control configured by a programmable controller, a microcomputer, etc. It may be a device. The control device may include a portion configured by software and a portion configured by hardware.

The control circuit 85 detects at least one of the following: the lock sensor 70 detects that the dump frame 20 is fixed by the lock device 60, and the floor landing sensor 75 detects that the dump frame 20 lands on the floor. In certain predetermined cases, the expansion and contraction operation of the slide cylinder 50 by the operation switch 80 is permitted. As shown in FIG. 7, the control circuit 85 has a contact 86 that is connected when the lock sensor 70 detects the locked state of the lock device 60, and a contact 86 that is connected when the landing sensor 75 detects that the dump frame 20 has landed on the floor. a contact 87 that is connected when the operation switch 80 is used to extend the slide cylinder 50; a contact 88 that is connected when the operation switch 80 is used to retract the slide cylinder 50; It is equipped with 89 and.

As shown in FIG. 7, in the control circuit 85, an operable condition determination circuit 85A includes a contact 86 and a contact 87. In the discrimination circuit 85A, the contact 86 and the contact 87 are provided in parallel. Therefore, when the lock sensor 70 detects that the dump frame 20 is fixed, or when the floor landing sensor 75 detects that the dump frame 20 lands on the floor, the determination circuit 85A is connected. Hereinafter, the state in which the lock sensor 70 detects that the dump frame 20 is fixed, and the state in which the landing sensor 75 detects that the dump frame 20 has landed on the chassis frame 10 will be described. It is said that the floor sensor 75 is ON. In addition, a state in which no detection is performed is also called OFF. The operation circuit 85B includes a contact 88 and a contact 89, and is connected in series with the discrimination circuit 85A. In the operation circuit 85B, a system including a contact 88 and a system including a contact 89 are branched. The system including the contact point 88 is connected to the hydraulic circuit on the side that extends the slide cylinder 50. A system including the contact point 89 is connected to a hydraulic circuit on the side that retracts the slide cylinder 50. Therefore, when at least one of the landing sensor 75 and the lock sensor 70 is ON, the slide cylinder 50 can be extended or retracted. Although not shown, the operable condition determination circuit 85A may further include other circuits and contacts based on other operable conditions.

[Sliding movement of loading platform]
FIG. 8 is a flowchart related to the sliding operation of the loading platform 30. Here, the operation of sliding the loading platform 30 rearward from the frontmost position and touching the ground will be described. As shown in FIG. 8, in step S01 of grounding the loading platform 30, the operation switch 80 is used to move the loading platform 30 backward. In step S02, it is determined whether the landing sensor 75 is turned on. When the landing sensor 75 is ON (when the result of step S02 is YES), the sliding operation of the loading platform 30 is permitted in step S04.

If the landing sensor 75 is turned off in step S02 (if the result of step S02 is NO), it is determined in step S03 whether the lock sensor 70 is turned on. When the lock sensor 70 is ON (when the result of step S03 is YES), sliding movement of the loading platform 30 is permitted in step S04. If the lock sensor 70 is OFF (if the result of step S03 is NO), the sliding movement of the loading platform 30 is disabled in step S05. Note that "determination" in steps S02 and S03 here means a result based on whether the corresponding part of the control circuit 85 is connected or disconnected.

When the loading platform 30 is to be slid rearward from the frontmost position, the locking device 60 is in an unlocked state at step S01. Therefore, the lock sensor 70 is OFF, and the result of step S03 is NO. However, at this time, if the dump frame 20 has landed on the chassis frame 10, the landing sensor 75 is ON, and the result of step S02 is YES. Therefore, the sliding operation of the loading platform 30 can be started.

When the loading platform 30 is retreated and moved from the frontmost position, the locking device 60 enters the locked state. As a result, the lock sensor 70 is turned on.

When the loading platform 30 is further moved backward, the loading platform 30 starts to rotate backward. At this time, the dump frame 20 receives, via the guide frame 40, a rotational force that causes the loading platform 30 to tilt. Even if the loading platform 30 receives a force that tends to tilt, the dump frame 20 will not dump because it is fixed to the chassis frame 10 by the locking device 60. However, due to the rotational force of the loading platform 30, the dump frame 20 may warp. For example, if a construction vehicle is placed at the rear of the loading platform 30 and the load applied to the dump frame 20 is high, such a situation may occur.

FIG. 9 is a side view of the loader dump 1, which is a schematic diagram showing the warpage of the dump frame 20. As shown in FIG. 9, when the dump frame 20 receives a force from the loading platform 30, the central portion of the dump frame 20, which is engaged with the rollers of the loading platform 30 via the guide frame 40, protrudes upward. This warpage of the dump frame 20 may cause the landing sensor 75 to turn off.

In a conventional loader dump, whether or not the dump frame has landed on the chassis frame is detected by a landing sensor similar to the landing sensor 75 of this embodiment. As far as the dumping state of the dump frame is concerned, whether or not the cargo bed can be slid has been determined based only on the detection results of the landing sensors. Therefore, when the landing sensor is turned off due to the above-mentioned warping of the dump frame, it becomes impossible to slide the cargo platform.

If the detection range of the landing sensor is expanded so that the landing sensor does not turn off even if the dump frame warps, the above-mentioned problem can be suppressed. However, such a response is not appropriate because the loading platform can be slid even when the dump frame has not completely landed on the floor.

In contrast, the loader dump 1 according to the present embodiment includes a lock sensor 70 that detects that the lock device 60 is fixing the dump frame 20. The control circuit 85 is configured to permit the operation switch 80 to extend and retract the slide cylinder 50 in a predetermined case, including when the lock sensor 70 detects that the dump frame 20 is fixed. Detection of fixation of the dump frame 20 by the lock sensor 70 is not affected by warping of the dump frame 20. Therefore, the lock sensor 70 will not be turned off due to the load applied to the dump frame 20. Therefore, according to the loader dump 1 according to the present embodiment, even in a situation where the load applied to the dump frame 20 is large, the sliding operation of the loading platform 30 is not interrupted midway and can be continued.

[Other effects of this embodiment]
Below, other effects that can be achieved by the loader dump 1 according to this embodiment will be described.

In this embodiment, the loader dump 1 includes a landing sensor 75 that is provided behind the lock sensor 70 and detects that the dump frame 20 has landed on the chassis frame 10. According to this configuration, the landing sensor 75 detects landing of the dump frame 20 on the floor, which the lock sensor 70 does not directly detect. Therefore, according to the loader dump 1 according to the present embodiment, landing of the dump frame 20 on the chassis frame 10 can be reliably detected.

In the present embodiment, the control circuit 85 determines at least one of the following: that the lock sensor 70 detects that the dump frame 20 is fixed; and that the floor landing sensor 75 detects that the dump frame 20 lands on the floor. In a predetermined case including one of the two, the operation switch 80 is allowed to extend and contract the slide cylinder 50. According to this configuration, even if either the lock sensor 70 detects that the dump frame 20 is fixed or the landing sensor 75 does not detect that the dump frame 20 has landed on the floor, the slide cylinder 50 does not extend or contract. Operation is allowed. Therefore, according to the loader dump 1 according to the present embodiment, it becomes easier to continue the sliding operation of the loading platform 30.

In this embodiment, the locking device 60 releases the fixation of the dump frame 20 when the loading platform 30 is located in front of a predetermined position, and releases the dump frame 20 when the loading platform 30 is located behind the predetermined position. It is configured to fix the frame 20. According to this configuration, when the loading platform 30 is located ahead of the predetermined position, the lock sensor 70 is OFF. However, during that time, the sliding operation of the loading platform 30 is permitted based on detection of landing of the dump frame 20 by the landing sensor 75. The unintentional turning off of the landing sensor 75 due to the warping of the dump frame 20 basically occurs after the loading platform 30 has retreated to a certain extent and started rotating. Therefore, when the loading platform 30 is located at the front and the lock sensor 70 is in the OFF state, it is unlikely that the landing sensor 75 will also be OFF at the same time.

In the present embodiment, the loader dump 1 is connected to a loading platform 30, and when the loading platform 30 is located in front of a predetermined position, the loader dump 1 has a lock release plate 36 that comes into contact with the hook 61 and pushes the hook 61 to the unlocked position. We are prepared. According to this configuration, by positioning the loading platform 30 ahead of a predetermined position, the dump frame 20 can be unlocked by the locking device 60 without any particular control.

In this embodiment, the locking device 60 has a hook 61 that moves between a locking position where the dump frame 20 is engaged with the chassis frame 10 and an unlocking position where it is separated from the chassis frame 10. We are prepared. The lock sensor 70 detects that the lock device 60 is fixing the dump frame 20 by detecting that the hook 61 is located at the lock position. According to this configuration, by detecting the position of the hook 61 with the lock sensor 70, it is possible to reliably detect that the locking device 60 is fixing the dump frame 20. Note that the hook 61 may be separated from the dump frame 20 instead of from the chassis frame 10 in the unlocked position.

[Other embodiments]
The loader dump 1 according to one embodiment of the present invention has been described above. However, the invention can also be implemented in other embodiments.

For example, in the embodiment described above, the first sensor provided near the lock device 60 is the lock sensor 70 that detects that the lock device 60 is fixing the dump frame 20. However, the first sensor is not limited to this. The first sensor may be a sensor that is provided near the lock device 60 and detects that the dump frame 20 has landed on the chassis frame 10. For example, the second sensor may be a sensor that is provided on the chassis frame 10 and detects the dump frame 20. Alternatively, the second sensor may be a sensor that is provided on the dump frame 20 and detects the chassis frame 10, for example. Since such a first sensor is provided near the locking device 60, it is not easily affected by warpage of the dump frame 20. Therefore, the first sensor can also reduce the influence of the warpage of the dump frame 20, making it easier to continue the sliding operation of the dump frame 20.

Further, for example, in the embodiment described above, the fact that the locking device 60 fixes the dump frame 20 is detected by the position of the hook 61, but it may be detected by other methods. For example, the locking device may be driven by an actuator such as a cylinder to lock or unlock the dump frame. In such a case, the lock sensor may detect that the lock device is fixing the dump frame by, for example, detecting the state of the actuator.

Unless otherwise specifically stated, the embodiments do not limit the invention. For example, the loader dump includes a first sensor that is provided near the locking device and detects that the locking device is fixing the dump frame or that the dump frame has landed on the chassis frame, The second sensor may not be provided.

1 Loader dump (dump truck)
10 Chassis frame 15 First rotation shaft 20 Dump frame 25 Second rotation shaft 30 Loading platform 36 Lock release plate (lock release member)
50 Slide cylinder (cylinder)
51 Rod 60 Lock device 61 Hook (engaging member)
70 Lock sensor (first sensor)
75 Implantation sensor (second sensor)
80 Operation switch (operation end)
85 Control circuit (control device)

Claims (6)

A chassis frame extending in the front and rear direction,
a first rotation shaft provided on the chassis frame and extending in the vehicle width direction;
a dump frame arranged on the chassis frame and rotating around the first rotation axis;
a second rotation shaft provided on the dump frame and extending in the vehicle width direction;
a cylinder that includes a rod that is extendable and retractable in the front-rear direction and rotates around the second rotation axis;
a loading platform connected to the rod, which moves in the front-rear direction according to the expansion and contraction of the rod, and rotates around the second rotation axis together with the cylinder;
a locking device capable of fixing a front end of the dump frame and the chassis frame in a state where the dump frame is placed on the chassis frame;
a first sensor that is provided near the locking device and detects that the locking device is fixing the dump frame or that the dump frame has landed on the chassis frame;
an operating end capable of expanding and contracting the cylinder;
a control device connected to the first sensor and the operating end and controlling the cylinder;
The control device permits an expansion/contraction operation of the cylinder by the operation end in a predetermined case including that the first sensor detects that the dump frame is fixed or landed on the floor.
Dump truck. The vehicle further includes a second sensor that is provided behind the first sensor and detects that the dump frame has landed on the chassis frame,
the first sensor is configured to detect that the locking device is fixing the dump frame;
The dump truck according to claim 1. The control device is configured to perform a predetermined operation including at least one of the first sensor detecting fixation of the dump frame, and the second sensor detecting landing of the dump frame. in this case, allowing the operation end to extend and contract the cylinder;
The dump truck according to claim 2. The locking device unlocks the dump frame when the loading platform is located in front of a predetermined position, and fixes the dump frame when the loading platform is located behind the predetermined position. do,
The dump truck according to claim 3. The locking device includes an engaging member that moves between a locking position in which the dump frame is engaged with the chassis frame and an unlocking position in which it is separated from the chassis frame or the dump frame. Prepare,
further comprising: an unlocking member connected to the loading platform and abutting the engaging member to push the engaging member to the unlocked position when the loading platform is located forward of the predetermined position;
The dump truck according to claim 4. The locking device includes an engaging member that moves between a locking position in which the dump frame is engaged with the chassis frame and an unlocking position in which it is separated from the chassis frame or the dump frame. Prepare,
The first sensor detects that the locking device is fixing the dump frame by detecting that the engaging member is located at the locking position.
The dump truck according to claim 2.

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