Seat belt device and work vehicle

Abstract

To provide a seat belt device capable of inhibiting attachment in a predetermined condition with a simple configuration.SOLUTION: A fastening mechanism 41 of a seat belt device 4 includes: a tongue plate 50 forming a tongue side engagement part 50a; a buckle 51 forming a buckle side engagement part 61a engaged with the tongue side engagement part 50a; an engagement inhibition member 52 disposed so as to be movable between an engagement inhibition position Px to inhibit engagement of the tongue side engagement part 50a with the buckle side engagement part 61a, and an engagement permission position Py to enable engagement of the tongue side engagement part 50a with the buckle side engagement part 61a; a driving source 80 for operating the engagement inhibition member 52; and a control unit 54 for controlling operation of the driving source 80 so as to arrange the engagement inhibition member 52 in the engagement inhibition position Px in a state that a safety frame disposed in a vehicle body is in a tilted posture, and to arrange the engagement inhibition member 52 in the engagement permission position Py in a state that the safety frame is in a standing posture.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a seat belt device and a work vehicle equipped with the same. [Background technology]

[0002] Conventionally, a gate-shaped safety frame called a ROPS (Roll-Over Protective Structure) has been installed in the driver's seat in some cases to protect the driver in the event that a work vehicle such as a tractor falls or overturns.

[0003] Such safety frames generally have a structure that can be folded behind or in front of the driver's seat to avoid contact with obstacles when parking, as described in Patent Document 1, for example.

[0004] However, if the driver puts on the seat belt and drives the vehicle with the safety frame folded, it may be difficult for the driver to escape if the vehicle falls or overturns. In this regard, in Patent Document 1, when the safety frame is folded, the seat belt is retracted, making it impossible to fasten the seat belt, thereby ensuring safety. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 2-57756 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology described in Patent Document 1 raises concerns that the structure becomes complicated because the seat belt is retracted in conjunction with the operation of the safety frame. Also, even if the seat belt is retracted, if the amount of retraction is insufficient, depending on the driver's physique, the seat belt may still be fastened even when the frame is folded, and this does not necessarily solve the safety problems described above.

[0007] SUMMARY OF THE INVENTION The present invention provides a seat belt device with a simple configuration that can prevent the seat belt from being fastened under predetermined conditions, and a work vehicle equipped with the same. [Means for solving the problem]

[0008] A seat belt device according to one aspect of the present invention is provided in a work vehicle having a retractable gate-shaped safety frame disposed behind a driver's seat that can switch between an upright position extending toward above the driver's seat and a reclined position extending toward the rear of the driver's seat. The seat belt device is provided in the driver's seat, and includes a belt that can be disposed in the width direction of the driver's seat, and a fastening mechanism that is provided midway or at an end of the belt and can switch between an engaged state in which the belt is suspended over the driver's seat and a released state in which the belt is released from the driver's seat. The fastening mechanism includes a tongue plate that forms a tongue-side engaging portion, The safety frame includes a buckle that forms a buckle-side engaging portion that engages with the tongue-side engaging portion; an engaging preventing member that is movable between an engaging preventing position that prevents engagement between the tongue-side engaging portion and the buckle-side engaging portion and an engaging allowing position that allows engagement between the tongue-side engaging portion and the buckle-side engaging portion; a driving source that operates the engaging preventing member; and a control device that controls the operation of the driving source so that the engaging preventing member is positioned at the engaging preventing position when the safety frame is in the reclined position, and so that the engaging preventing member is positioned at the engaging allowing position when the safety frame is in the upright position.

[0009] In the above-described seat belt device, the buckle may have a buckle case that forms an insertion port into which the tongue plate is inserted, and the buckle side engagement portion, the engagement preventing member, the drive source, and the control device may be provided within the buckle case.

[0010] In the above-described seat belt device, the engagement preventing member may have a blocking body that can interfere with the tongue plate inserted into the insertion port, and the blocking body that is in the engagement preventing position may be positioned by the drive source to a location where it will interfere with the tongue plate before the tongue side engaging portion engages with the buckle side engaging portion, and the blocking body that is in the engagement allowing position may be positioned by the drive source to a location where it will not interfere with the tongue plate until the tongue side engaging portion engages with the buckle side engaging portion.

[0011] In the seat belt device, the blocking body that is in the engagement blocking position may be positioned by the drive source at a location forward of the buckle-side engaging portion in an insertion direction of the tongue plate.

[0012] In the above-mentioned seat belt device, the blocking body that is in the engagement permission position may be positioned by the drive source at a location on the opposite side of the buckle side engagement portion from the insertion port, which is further back in the insertion direction than the buckle side engagement portion.

[0013] In the seat belt device, the engagement preventing member is actuated by an external force from the tongue plate. Tongue plate The blocking member may further include an elastic member that generates a reaction force against the external force against the blocking member that moves in the insertion direction.

[0014] In the above-described seat belt device, the buckle may have a buckle case that forms an insertion port into which the tongue plate is inserted, the tongue-side engagement portion may be a through hole that penetrates the tongue plate in the plate thickness direction, the buckle-side engagement portion may be an engagement protrusion that is provided within the buckle case and that is capable of advancing from a non-engagement position located outside the through hole when the tongue plate is inserted into the insertion port toward an engagement position located within the through hole and engaging with the through hole, the engagement preventing member may have a fixing body that can fix the engagement protrusion to the non-engagement position, the fixing body that is in the engagement preventing position may be positioned by the driving source at a location that fixes the engagement protrusion to the non-engagement position, and the fixing body that is in the engagement allowing position may be positioned by the driving source at a location that allows the engagement protrusion to advance from the non-engagement position toward the engagement position.

[0015] In the above-described seat belt device, the buckle has a buckle case that forms an insertion port into which the tongue plate is inserted, the tongue side engagement portion is a through hole that penetrates the tongue plate in the plate thickness direction, the buckle side engagement portion is an engagement protrusion that is provided in the buckle case and is capable of advancing from a non-engagement position located outside the through hole when the tongue plate is inserted into the insertion port to an engagement position located within the through hole and engaging with the through hole, the engagement preventing member has a blocking body that can interfere with the engagement protrusion when the tongue plate is inserted into the insertion port, the blocking body that is in the engagement preventing position may be positioned by the drive source to a location where it blocks at least a portion of the through hole, and the blocking body that is in the engagement allowing position may be positioned by the drive source to a location where it opens the through hole.

[0016] A work vehicle according to one embodiment of the present invention comprises the above-described seat belt device, a vehicle body in which the driver's seat equipped with the seat belt device is located, the safety frame provided on the vehicle body, and a frame attitude detection device that detects when the safety frame is in the reclined attitude, and the control device in the seat belt device controls the operation of the drive source based on a signal from the frame attitude detection device.

[0017] The above-mentioned work vehicle may further include a seating detection device that detects whether a driver is seated in the driver's seat in the vehicle body, and the control device in the seat belt device may control the operation of the drive source to position the engagement prevention member in the engagement prevention position when the driver is seated in the driver's seat and the safety frame is in the reclined position, based on signals from the seating detection device and the frame posture detection device.

[0018] The above-mentioned work vehicle may further include a turn indicator provided on the safety frame, a power source for operating the turn indicator, indicator wiring connecting the power source and the turn indicator, and seat belt drive wiring branching off from the indicator wiring and connected to the drive source and the control device, supplying electric power as motive power to the drive source and the control device. [Effects of the Invention]

[0019] According to the above-described seat belt device, it is possible to prevent the seat belt from being fastened under predetermined conditions with a simple configuration. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is an overall side view of a work vehicle according to a first embodiment of the present invention. [Figure 2] 10A and 10B are side views of the safety frame of the work vehicle showing how the safety frame's posture is changed, where (a) is a view of the safety frame in an upright posture, and (b) is a view of the safety frame in a reclined posture. [Figure 3] FIG. 2 is a perspective view of the safety frame of the work vehicle in an upright position. [Figure 4] FIG. 2 is an enlarged perspective view of the driver's seat of the work vehicle. [Figure 5] 1 is a top view of the seat belt device of the work vehicle, showing the inside of the buckle through a transparent view, in which (a) shows the state in which the engagement preventing member is positioned in the engagement preventing position, and (b) shows the state in which the engagement preventing member is positioned in the engagement allowing position. [Figure 6] 10A and 10B are side views schematically showing engagement between a tongue plate and a buckle in the seat belt device of the work vehicle, in which FIG. 10A shows a state in which the tongue plate is in front of the tongue lock member, FIG. 10B shows a state in which the tongue plate is in contact with the tongue lock member, and FIG. 10C shows a state in which the tongue plate is engaged with the tongue lock member. [Figure 7] 3 is a hardware configuration diagram of a control device in the seat belt device of the work vehicle. FIG. [Figure 8] 3 is a functional block diagram of a control device in a seat belt device of the work vehicle. FIG. [Figure 9] 4 is a diagram showing a control flow of a control device in a seat belt device of the work vehicle. FIG. [Figure 10] FIG. 10 is a side view schematically showing the engagement between the tongue plate and the buckle in a seat belt device for a work vehicle according to a second embodiment of the present invention, showing a state in which the buckle side engagement portion is fixed in a non-engaged position. [Figure 11] 10A and 10B are side views schematically illustrating the engagement between a tongue plate and a buckle in a seatbelt device for a work vehicle according to a second embodiment of the present invention, showing a state in which the buckle-side engagement portion is released from its disengagement position, where (a) shows a state in which the tongue plate is in front of the tongue lock member, (b) shows a state in which the tongue plate is in contact with the tongue lock member, and (c) shows a state in which the tongue plate is engaged with the tongue lock member. [Figure 12]10A and 10B are top views showing a seat belt device for a work vehicle according to a third embodiment of the present invention, with components around an engagement preventing member being transparently shown, and FIG. 10A shows a state in which the engagement preventing member is disposed in an engagement preventing position, and FIG. 10B shows a state in which the engagement preventing member is disposed in an engagement allowing position. DETAILED DESCRIPTION OF THE INVENTION

[0021] First Embodiment (Overall composition) A work vehicle 100 according to an embodiment of the present invention will now be described. The work vehicle 100 is, for example, an agricultural machine such as a riding tractor, and is operated by a driver while traveling to perform a predetermined task. As shown in FIG. 1, the work vehicle 100 of this embodiment includes a vehicle body 1, a driver's seat 2, a safety frame 3, and a seat belt device 4 provided on the vehicle body 1, a frame attitude detection device 5 that detects the attitude of the safety frame 3, a seating detection device 6 that detects whether the driver is seated in the driver's seat 2, and a belt fastening detection device 7 that detects the fastening state of the seat belt device 4.

[0022] (Vehicle body) The vehicle body 1 includes a running device 10 that includes running wheels 10a, an engine 11 that drives the running device 10, a battery (power source) 12 that supplies power to various devices, and the like.

[0023] The traveling wheels 10a of the traveling device 10 include front wheels disposed at the front of the work vehicle and rear wheels disposed at the rear, and the front wheels can be steered by the driver.

[0024] (Driver's seat) The driver's seat 2 is disposed in the upper part of the vehicle body 1. Note that the vehicle body 1 of this embodiment is not provided with a cabin that covers the driver's seat 2 from above.

[0025] (Safety frame) The safety frame 3 is a gate-shaped, foldable frame located behind the driver's seat 2, and is switchable between an upright position P1 extending above the driver's seat 2 in a direction perpendicular to the ground and a reclined position P2 extending toward the rear of the driver's seat 2. The safety frame 3 of this embodiment is arranged with a gap in the width direction (hereinafter simply referred to as the width direction) of the driver's seat 2, each positioned outside the width direction of the driver's seat 2, and has a pair of bases 30 protruding from the vehicle body 1, a pair of vertical pillars 31 supported by each base 30 and extending in a direction away from the bases 30, a horizontal pillar 32 connecting the pair of vertical pillars 31 at their upper ends and extending in the width direction, and a positioning pin 33 provided between the bases 30 and the vertical pillars 31, which passes through the base 30 and is inserted into the vertical pillars 31.

[0026] As shown in Fig. 2, when the position of the safety frame 3 is changed, the positioning pin 33 is removed, the vertical pillar 31 is rotated relative to the base 30, the position of the safety frame 3 is changed, and then the positioning pin 33 is inserted again. That is, each base 30 is formed with holes for inserting the positioning pin 33, namely, a first positioning hole 30a into which the positioning pin 33 is inserted in the upright position P1, and a second positioning hole 30b into which the positioning pin 33 is inserted in the reclined position P2. The dimensions of the safety frame 3 are set so that the upper end of the safety frame 3 in the upright position P1 is located above the driver seated in the driver's seat 2 (see Fig. 1). Note that the structure for switching the position of the safety frame 3 is not limited to that of this embodiment.

[0027] 3, the safety frame 3 of this embodiment is provided with a turn signal 37. An indicator wiring 38 extending from the battery 12 of the vehicle body 1 is connected to the turn signal 37, and the turn signal 37 is operated by receiving power from the battery 12.

[0028] (Frame position detection device) The frame attitude detection device 5 has a sensor that detects the attitude of the safety frame 3, i.e., the upright attitude P1 and the tilted attitude P2. This sensor is not particularly limited, but in the case of this embodiment, for example, a contact detection sensor is used that can detect the attitude of the safety frame 3 by detecting contact with the first positioning hole 30a or the second positioning hole 30b (see FIG. 2), which is the contact portion of the positioning pin 33 with the base 30. In this embodiment, the frame attitude detection device 5 is provided inside the safety frame 3.

[0029] (Seating detection device) 4, the seating detection device 6 has a sensor that detects whether or not the driver is seated in the driver's seat 2. This sensor is not particularly limited, but for example, a sensor that is provided inside the seat surface of the driver's seat 2 and is configured with a strain gauge or the like that changes resistance value depending on the weight of the driver is used.

[0030] (Belt wearing detection device) 5(a) and 5(b), the belt fastening detection device 7 has a sensor that detects whether the seat belt device 4, which will be described in detail later, is fastened, i.e., whether a tongue plate 50, which will be described later, is engaged with a buckle 51. This sensor is not particularly limited, but for example, it is provided in a buckle case 60 of the buckle 51, which will be described later, and can detect whether the seat belt device 4 is fastened by detecting a short circuit when the buckle 51 is engaged with a tongue plate 50, which will be described later.

[0031] (seat belt device) Next, the seat belt device 4 will be described in detail. Returning to Figure 4, the seat belt device 4 includes a belt 40 that is arranged so as to be positionable in the width direction of the driver's seat 2, and a fastening mechanism 41 that is arranged at the end of the belt 40 and can switch between a connected state in which the belt 40 is suspended over the driver's seat 2, and a released state in which the belt 40 is released from the driver's seat 2.

[0032] (belt) When the driver wears the seat belt device 4, the belt 40 extends in the width direction along the seat surface of the driver's seat 2 and is arranged above the abdomen of the driver.

[0033] (fastening mechanism) The fastening mechanism 41 is provided at one end in the width direction of the driver's seat 2 (see FIG. 4). The fastening mechanism 41, together with the belt 40, constitutes a two-point seat belt. More specifically, as shown in FIGS. 5(a) and 5(b), the fastening mechanism 41 includes a tongue plate 50, a buckle 51 with which the tongue plate 50 engages, an engagement preventing member 52 capable of preventing the tongue plate 50 from engaging with the buckle 51, a drive device 53 that operates the engagement preventing member 52, and a control device 54 that controls the drive device 53.

[0034] (Tongue plate) The tongue plate 50 is a metal plate and is connected to an end of the belt 40. The tongue plate 50 also forms a tongue-side engaging portion 50a. The tongue-side engaging portion 50a is a through-hole that penetrates the tongue plate 50 in the plate thickness direction.

[0035] (buckle) The buckle 51 is supported on the side surface of the driver's seat 2 (see FIG. 4). The buckle 51 has a buckle case 60 and a tongue lock member 61 housed in the buckle case 60.

[0036] (Buckle case) The buckle case 60 is box-shaped, and has an insertion port 60a that opens to the front side in the insertion direction D of the tongue plate 50 so that the tongue plate 50 can be inserted into the inner space of the buckle case 60.

[0037] (Tanglock material) The tongue lock member 61 is made of metal and is disposed inside the buckle case 60 at the rear side of the insertion opening 60a of the buckle case 60 in the insertion direction D, and forms a buckle side engaging portion 61a that engages with the tongue side engaging portion 50a.

[0038] As shown in Figures 6(a) to 6(c), the buckle-side engaging portion 61a of the tongue lock member 61 of this embodiment is an engaging protrusion that can advance from a non-engagement position Pa located outside the tongue-side engaging portion 50a (through hole) toward an engagement position Pb located inside the tongue-side engaging portion 50a (through hole) and engaged with the tongue-side engaging portion 50a when the tongue plate 50 is inserted into the insertion port 60a.

[0039] In detail, the tongue lock member 61 is biased upward from below on the driver's seat 2 side by an elastic member 62, so that the buckle side engagement portion 61a (engagement protrusion) is normally positioned at the engagement position Pb as shown in Figure 6(a). As shown in FIG. 6(b), when the tongue plate 50 is inserted into the buckle case 60, the tongue plate 50 presses in the insertion direction D against an inclined surface 61x formed on the buckle-side engagement portion 61a (engagement protrusion), which is inclined upward toward the back side in the insertion direction D. As a result, the tongue lock member 61 is pushed downward against the biasing force of the elastic member 62, the elastic member 62 is compressed, and the buckle-side engagement portion 61a (engagement protrusion) temporarily retreats to the non-engagement position Pa. Thereafter, when the tongue plate 50 is further inserted as shown in FIG. 6(c), the restoring force of the elastic member 62 causes the buckle-side engagement portion 61a (engagement protrusion) to advance toward the tongue-side engagement portion 50a (through-hole), i.e., toward the engagement position Pb.

[0040] (Engagement prevention member) 5, the engagement preventing member 52 is provided to be movable between an engagement preventing position Px (see FIG. 5(a)) that prevents engagement between the tongue side engagement portion 50a (through hole) and the buckle side engagement portion 61a (engagement protrusion), and an engagement allowing position Py (see FIG. 5(b)) that allows engagement between the tongue side engagement portion 50a and the buckle side engagement portion 61a. In this embodiment, the engagement preventing member 52 is housed in the buckle case 60, and has a blocking body 70 that can interfere with the tongue plate 50 inserted into the insertion port 60a, a support body 71 that supports the blocking body, and an elastic body 72 that urges the blocking body 70 toward the front in the insertion direction D.

[0041] The blocking body 70 extends in the buckle width direction intersecting with the insertion direction D. At the engagement preventing position Px, the blocking body 70 is positioned by a driving source 80 (described in detail below) at a location where it will interfere with the tongue plate 50 before the tongue side engaging portion 50a engages with the buckle side engaging portion 61a, and at the engagement allowing position Py, the blocking body 70 is positioned by a driving source 80 (described in detail below) at a location where it will not interfere with the tongue plate 50 until the tongue side engaging portion 50a engages with the buckle side engaging portion 61a.

[0042] 5(a), the blocking body 70 is disposed in a position closer to the buckle-side engaging portion 61a in the insertion direction D of the tongue plate 50, i.e., between the insertion opening 60a and the buckle-side engaging portion 61a, at the engagement blocking position Px, to block the insertion of the tongue plate 50. Note that the blocking body 70 may be disposed in such a way that it protrudes from the insertion opening 60a to the outside of the buckle case 60 at the engagement blocking position Px.

[0043] On the other hand, as shown in Figure 5(b), the blocking body 70 is positioned at a location further back in the insertion direction D than the buckle side engaging portion 61a in the insertion direction D at the engagement permission position Py, i.e., on the opposite side of the buckle side engaging portion 61a from the insertion opening 60a, allowing the tongue plate 50 to be inserted.

[0044] The support body 71 is rod-shaped or plate-shaped and extends from the blocking body 70 toward the rear in the insertion direction D. A rack gear 81b of the drive unit 53, which will be described in detail later, is provided on the support body 71, and the support body 71 moves in the insertion direction D together with the blocking body 70 by this rack gear 81b.

[0045] The elastic body 72 is a coil spring or the like provided in the support body 71 between the blocking body 70 and a rack gear 81b of the drive device 53, which will be described in detail later, and biases the blocking body 70 from the rear side toward the front side in the insertion direction D. That is, the elastic body 72 generates a reaction force against the external force from the tongue plate 50 to the blocking body 70, which moves in the insertion direction D due to the external force.

[0046] (Drive unit) The drive device 53 is disposed inside the buckle case 60 at a position further back in the insertion direction D than the tongue lock member 61, and causes the engagement preventing member 52 to slide in the insertion direction D. That is, the drive device 53 has a drive source (e.g., a motor) 80 and a transmission mechanism 81 that transmits power from the drive source 80 to the engagement preventing member 52.

[0047] A seatbelt drive wiring 39 branching off from the indicator wiring 38 (see FIG. 3) of the direction indicator 37 is connected to the drive source 80, and power is supplied from the battery 12 of the vehicle body 1. The transmission mechanism 81 has a pinion gear 81a that is rotated by the drive source 80, and a rack gear 81b that meshes with the pinion gear 81a and is provided on the support body 71 of the engagement preventing member 52. When the pinion gear 81a is rotated by the drive source 80, the support body 71 moves together with the rack gear 81b in both directions in the insertion direction D, and as a result, the engagement preventing member 52 slides in both directions in the insertion direction D, becoming movable between an engagement preventing position Px and an engagement allowing position Py.

[0048] (Control device) The control device 54 is housed in the buckle case 60, and controls the operation of the drive source 80 in the drive device 53 so that the engagement preventing member 52 is disposed in the engagement preventing position Px when the safety frame 3 is in the reclined position P2 (see FIG. 1), and the engagement preventing member 52 is disposed in the engagement permitted position Py when the safety frame 3 is in the upright position P1 (see FIG. 1). That is, the control device 54 is electrically connected to the frame position detection device 5, the seating detection device 6, and the belt fastening detection device 7 via communication lines, receives signals from the frame position detection device 5, the seating detection device 6, and the belt fastening detection device 7, and operates the drive source 80 in the drive device 53 based on these signals. The standard of the communication line is not particularly limited, and it may be wired or wireless.

[0049] As shown in FIG. 7, the control device 54 has a computer 500, which has a CPU (Central Processing Unit) 510, memory 520 such as ROM (Read Only Memory) or RAM (Random Access Memory), a non-volatile storage device 530 such as an HDD (Hard Disk Drive) or SSD (Solid State Drive), a power supply 540, an input interface 550, an output interface 560, and bus wiring 570 connecting these.

[0050] The CPU 510 is a central processing unit that executes a program for a control method described later. The memory 520 is used as a work area and storage area for the CPU 510, and the storage device 530 stores the operating system, programs, etc. executed by the CPU 510. The power supply device 540 is connected to a seat belt drive wiring 39 that branches off from the indicator wiring 38 (see FIG. 3) of the above-mentioned direction indicator 37, and is powered by the battery 12 of the vehicle body 1.

[0051] That is, as shown in FIG. 8, the control device 54 includes a frame posture information acquisition unit 90, a seating information acquisition unit 91, a belt fastening information acquisition unit 92, and a control signal generation and transmission unit 93.

[0052] The frame posture information acquisition unit 90 receives a signal from the frame posture detection device 5 and acquires information about the posture of the safety frame 3 (standing posture P1 or leaning posture P2). The seating information acquisition unit 91 receives a signal from the seating detection device 6 and acquires information on whether or not the driver is seated in the driver's seat 2.

[0053] The belt wearing information acquisition unit 92 receives a signal from the belt wearing detection device 7 and acquires information regarding whether the seat belt device 4 is worn or not, i.e., whether or not the tongue side engagement portion 50a (through hole) and the buckle side engagement portion 61a (engagement protrusion) are engaged.

[0054] The control signal generating and transmitting unit 93 generates a signal to operate the drive source 80 so that the engagement preventing member 52 is positioned at the engagement preventing position Px when the posture of the safety frame 3 is in the reclined posture P2 and the driver is seated in the driver's seat 2, and so that the engagement preventing member 52 is positioned at the engagement allowing position Py under other conditions, and transmits this signal to a motor driver (not shown) provided in the drive source 80.

[0055] Next, the flow (control method) of control of the drive source 80 by the control device 54 will be described with reference to FIG. First, a posture information acquisition step S1 is executed to acquire information about the posture of the safety frame 3. Then, a posture determination step S2 is executed to determine the posture of the safety frame 3. In this step S2, if the safety frame 3 is in a reclining posture P2, the result is "YES" and the process proceeds to a seating information acquisition step S3. On the other hand, if the safety frame 3 is in an upright posture P1, the result is "NO".

[0056] If the determination in the posture determination step S2 is "NO," i.e., if the engagement preventing member 52 is in the upright posture P1, the process proceeds to an allowed position determination step S10 in which the position of the engagement preventing member 52 is determined. In this allowed position determination step S10, if the engagement preventing member 52 is disposed at the engagement allowed position Py, the determination is "YES," and if the engagement preventing member 52 is not disposed at the engagement allowed position Py, i.e., if it is disposed at the engagement prevented position Px, the determination is "NO."

[0057] If the determination in the permitted position determination step S10 is "YES," the flow ends. On the other hand, if the determination in the permitted position determination step S10 is "NO," that is, if the engagement preventing member 52 is disposed at the engagement preventing position Px, the flow proceeds to the permission control signal generation / transmission step S11, where a control signal for moving the engagement preventing member 52 from the engagement preventing position Px to the engagement permitted position Py is generated and transmitted to the drive source 80, and the flow ends.

[0058] Returning to the posture determination step S2, after the determination of "YES" in this step S2, information regarding whether or not the driver is seated in the driver's seat 2 is obtained in the seating information acquisition step S3. Then, after the seating information acquisition step S3, the seating determination step S4 is executed. In this step S4, if the driver is seated in the driver's seat 2, the determination is "YES", and if the driver is not seated in the driver's seat 2, the determination is "NO". If the determination of "YES" in the seating determination step S4, i.e., if the driver is seated, the process proceeds to the blocked position determination step S5. On the other hand, if the determination of "NO" in the seating determination step S4, i.e., if the driver is not seated, the process proceeds to the above-mentioned permitted position determination step S10.

[0059] In the blocking position determination step S5 after the determination of "YES" in the seating determination step S4, the determination is "YES" if the engagement preventing member 52 is positioned at the engagement preventing position Px, and the determination is "NO" if the engagement preventing member 52 is positioned at the engagement permitted position Py. If the determination of "YES" in the blocking position determination step S5 is "YES," the flow ends. On the other hand, if the determination of "NO" in the blocking position determination step S5 is "NO," the flow proceeds to the blocking control signal generation / transmission step S6, where a control signal for moving the engagement preventing member 52 from the engagement permitted position Py to the engagement preventing position Px is generated and transmitted to the drive source 80.

[0060] (Action and effect) According to the work vehicle 100 of the present embodiment described above, when the safety frame 3 is in the reclined position P2 and the driver is seated in the driver's seat 2, the control device 54 of the seat belt device 4 slides the engagement preventing member 52 forward in the insertion direction D of the tongue plate 50 to place it in the engagement preventing position Px. By placing the engagement preventing member 52 in the engagement preventing position Px, the blocking body 70 can prevent the tongue plate 50 from being inserted into the buckle 51. Therefore, with the simple configuration of sliding the engagement preventing member 52, it is possible to prevent the seat belt device 4 from being fastened under the above-mentioned predetermined conditions, and it is possible to forcibly prevent the driver from accidentally fastening the seat belt device 4 when the safety frame 3 is in the reclined position P2, allowing the driver to use the work vehicle 100 with peace of mind.

[0061] Furthermore, the tongue lock member 61 forming the buckle side engaging portion 61a (engaging protrusion), the engagement preventing member 52, the drive device 53, and the control device 54 are housed within a buckle case 60 of the buckle 51. Therefore, by replacing an existing buckle with the buckle 51 of this embodiment, a mechanism for preventing the engagement between the tongue plate 50 and the buckle 51 can be easily added to the existing seat belt.

[0062] Furthermore, the blocking body 70 of the engagement preventing member 52 is positioned at a location where it interferes with the tongue plate 50 at the engagement preventing position Px, i.e., a location forward of the buckle-side engaging portion 61a (engagement protrusion) in the insertion direction D of the tongue plate 50. Therefore, at the engagement preventing position Px, the blocking body 70 is positioned to block the insertion opening 60a of the buckle case 60, making it impossible to insert the tongue plate 50 into the buckle 51, and reliably preventing the tongue plate 50 from engaging with the buckle 51.

[0063] Furthermore, the blocking body 70 of the engagement blocking member 52 is positioned in a location that does not interfere with the tongue plate at the engagement permitted position Py, i.e., a location further back than the buckle-side engaging portion 61a (engagement protrusion) in the insertion direction D of the tongue plate 50. Therefore, at the engagement permitted position Py, the blocking body 70 does not come into contact with the tongue plate 50 until the insertion of the tongue plate 50 is complete, allowing the tongue plate 50 and the buckle 51 to be reliably engaged with each other.

[0064] In addition, since the engagement preventing member 52 is provided with an elastic body 72, if the tongue plate 50 is inserted into the buckle 51 when the blocking body 70 is positioned at the engagement preventing position Px, the elastic body 72 absorbs the force in the insertion direction D, and the blocking body 70 can gently receive the tongue plate 50, thereby avoiding damage to the engagement preventing member 52.

[0065] Furthermore, by branching the seat belt drive wiring 39 from the indicator wiring 58 that supplies power from the battery 12 to the direction indicator 37 provided on the safety frame 3 and connecting this seat belt drive wiring 39 to the drive source 80 and the control device 54, it is possible to install the wiring for supplying power to the drive source 80 and the control device 54 from the side of the safety frame 3 that is closer to the driver's seat 2, without having to install new wiring on the battery 12 side, which makes it easy to install the seat belt device 4 even when replacing an existing seat belt.

[0066] In this embodiment, the engagement preventing member 52, the drive device 53, and the control device 54 do not necessarily have to be provided inside the buckle case 60.

[0067] Furthermore, the engagement preventing member 52 is not limited to sliding in the insertion direction D of the tongue plate 50, but may be configured to close / open the insertion port 60a, for example, by sliding in the belt width direction that intersects with the insertion direction D relative to the insertion port 60a of the buckle case 60.

[0068] Second Embodiment Next, a seatbelt device 4A for a work vehicle 100A according to a second embodiment of the present invention will be described with reference to Figures 10 and 11. In this embodiment, the configurations of an engagement preventing member 52A and a drive device 53A are different from those in the first embodiment. (Drive unit) The drive device 53A of this embodiment is provided inside the buckle case 60, and has, for example, as the drive source 80A, a solenoid actuator that constitutes an advancing mechanism operable in the advancing direction F (see FIG. 10) that is the opposite direction to the insertion direction D. Note that an actuator other than a solenoid actuator may be used as the drive source 80, and a device using a motor and rack and pinion like the drive device 53 of the first embodiment may be used as the drive device 53A, and is not particularly limited.

[0069] (Engagement prevention member) The engagement preventing member 52A is provided within the buckle case 60 and is movable between an engagement preventing position Px, which is a position where the buckle side engagement portion 61a (engagement protrusion) of the tongue lock member 61 is fixed to the non-engagement position Pa (see Figure 10), and an engagement allowing position Py, which is a position where the buckle side engagement portion 61a (engagement protrusion) is released from the non-engagement position Pa and can advance from the non-engagement position Pa toward the engagement position Pb (see Figure 11(a)).

[0070] More specifically, the engagement preventing member 52A has a lever-shaped fixed body 70A that connects the tongue lock member 61 to, for example, a solenoid actuator serving as the drive source 80 and converts a force in the advancing direction F input by the solenoid actuator into a force in the retracting direction of the tongue lock member 61. When the solenoid actuator serving as the drive source 80 is energized to push the fixed body 70A in the advancing direction F, the state shown in FIG. 11(a) changes to the state shown in FIG. 10, i.e., the fixed body 70A rotates about a fulcrum O to pull the tongue lock member 61 from the engaged position Pb toward the disengaged position Pa, and the buckle-side engaging portion 61a (engaging protrusion) is fixed at the disengaged position Pa. On the other hand, when the energization of the solenoid actuator serving as the drive source 80A is stopped, the state changes from the state shown in FIG. 10 to the state shown in FIG. 11(a), i.e., the fixation of the tongue lock member 61 at the disengaged position Pa by the fixed body 70A is released. When the tongue plate 50 is inserted into the insertion port 60a with the tongue lock member 61 released from its fixed position at the non-engagement position Pa, the tongue plate 50 presses the inclined surface 61x, pushing the tongue lock member 61 downward from the state in which the buckle-side engagement portion 61a (engagement protrusion) is disposed at the engagement position Pb (FIG. 11(a)), and the buckle-side engagement portion 61a (engagement protrusion) temporarily retreats to the non-engagement position Pa (FIG. 11(b)). When the tongue plate 50 is then further inserted, the restoring force of the elastic member 62 allows the buckle-side engagement portion 61a (engagement protrusion) to advance toward the tongue-side engagement portion 50a (through-hole) (FIG. 11(c)).

[0071] (Action and effect) In the work vehicle 100A of the present embodiment described above, when the safety frame 3 is in the reclined posture P2 and the driver is seated in the driver's seat 2, if the engagement preventing member 52A is placed in the engagement preventing position Px, the buckle-side engaging portion 61 a (engagement protrusion) is fixed to the non-engagement position Pa by the fixing body 70A of the engagement preventing member 52A. Even if the tongue plate 50 is inserted into the buckle 51 in this state, the buckle-side engaging portion 61 a (engagement protrusion) will be positioned outside the tongue-side engaging portion 50 a (through-hole), and the tongue plate 50 and the buckle 51 will not be able to engage with each other. Therefore, with the simple configuration in which the buckle-side engaging portion 61 a (engagement protrusion) is fixed to the non-engagement position Pa by the engagement preventing member 52A, it is possible to prevent the seat belt device 4A from being fastened, and it is possible to forcibly prevent the driver from accidentally fastening the seat belt device 4A when the safety frame 3 is in the reclined posture P2.

[0072] Third Embodiment Next, a seatbelt device 4B for a work vehicle 100B according to a third embodiment of the present invention will be described with reference to Fig. 12. In this embodiment, the configurations of an engagement preventing member 52B and a drive device 53B are different from those of the first and second embodiments.

[0073] (Engagement prevention member) The engagement preventing member 52B is provided on the tongue plate 50 and has, for example, a plate-shaped blocking body 70B that can interfere with the buckle-side engaging portion 61a (engagement protrusion) when the tongue plate 50 is inserted into the buckle 51. At the engagement preventing position Px, the blocking body 70B is positioned by a driving source 80B (described later) at a position where it blocks at least a part of the tongue-side engaging portion 50a (through hole) (see FIG. 12(a)), and at the engagement allowing position Py, the blocking body 70B is positioned by a driving source 80B (described later) at a position where it opens the tongue-side engaging portion 50a (through hole) (see FIG. 12(b)).

[0074] (Drive source) The drive device 53B has, for example, a drive source (e.g., a motor) 80B and a rack-and-pinion transmission mechanism 81B that transmits power from the drive source 80B to the engagement preventing member 52B, similar to the drive device 53 of the first embodiment, but the configuration of the drive device 53B is not particularly limited. The drive device 53B is, for example, provided on the belt 40 on the front side of the tongue plate 50 in the insertion direction D, and moves the blocking body 70B of the engagement preventing member 52B forward and backward on the tongue-side engagement portion 50a (through hole) in the insertion direction D. The configuration of the drive device 53B is not limited to the above-mentioned case, and an actuator, for example, may be used.

[0075] (Action and effect) In the work vehicle 100B of the present embodiment described above, when the safety frame 3 is in the reclined position P2 and the driver is seated in the driver's seat 2, if the engagement preventing member 52B is positioned at the engagement preventing position Px, the blocking body 70B of the engagement preventing member 52B is positioned at a location that blocks the tongue-side engaging portion 50a (through-hole). Even if the tongue plate 50 is inserted into the buckle 51 in this state, the buckle-side engaging portion 61a (engaging protrusion) cannot enter the tongue-side engaging portion 50a (through-hole), and the tongue plate 50 and the buckle 51 cannot be engaged. Therefore, with the simple configuration of blocking the tongue-side engaging portion 50a (through-hole) with the blocking body 70B of the engagement preventing member 52B, it is possible to prevent the seat belt device 4B from being fastened, and it is possible to forcibly prevent the driver from accidentally fastening the seat belt device 4 when the safety frame 3 is in the reclined position P2.

[0076] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. For example, the fastening mechanism 41 may be provided at a position midway along the belt 40 .

[0077] Furthermore, the conditions for positioning the engagement prevention members 52, 52A, 52B at the engagement prevention position Px do not have to include the condition of whether or not the driver is seated in the driver's seat 2, and the positions of the engagement prevention members 52, 52A, 52B may be determined simply based on the posture of the safety frame 3. [Industrial Applicability]

[0078] According to the seat belt device etc. of the present invention, it is possible to prevent fastening under predetermined conditions with a simple configuration. [Explanation of symbols]

[0079] 1 Vehicle body 2 Driver's seat 3 Safety Frame 4, 4A, 4B seat belt device 5 Frame position detection device 6. Seat detection device 12 Battery 37 Turn signal 38 Indicator wiring 39 Seat belt drive wiring 40 Belt 41 Fastening mechanism 50 Tongue Plate 50a Tongue side engagement portion 51 Buckle 52, 52A, 52B engagement prevention members 53, 53A, 53B drive unit 54 Control device 58 Indicator wiring 60 Buckle Case 60a outlet 61 Tanglock member 61a Buckle side engagement portion 70 Blocker 70A fixed body 70B Obturator 72 Elastic Body 80, 80A, 80B drive source 100, 100A, 100B work vehicles

Claims

1. A seat belt device provided in a driver's seat in a work vehicle that includes a retractable gate-shaped safety frame that is arranged behind a driver's seat and can switch between an upright position extending toward above the driver's seat and a reclined position extending toward the rear of the driver's seat, a belt that can be arranged in the width direction of the driver's seat; a fastening mechanism provided at a midpoint or end of the belt, capable of switching between a fastened state in which the belt is suspended over the driver's seat and a released state in which the belt is released from the driver's seat; Equipped with The fastening mechanism includes: a tongue plate forming a tongue-side engagement portion; a buckle forming a buckle-side engaging portion that engages with the tongue-side engaging portion; an engagement preventing member provided to be movable between an engagement preventing position that prevents engagement between the tongue side engagement portion and the buckle side engagement portion and an engagement allowing position that allows engagement between the tongue side engagement portion and the buckle side engagement portion; a drive source that operates the engagement preventing member; a control device that controls the operation of the drive source so as to place the engagement preventing member at the engagement preventing position when the safety frame is in the tilted posture, and to place the engagement preventing member at the engagement allowing position when the safety frame is in the upright posture; A seat belt device comprising:

2. the buckle has a buckle case that forms a receptacle into which the tongue plate is inserted, 2. The seat belt device according to claim 1, wherein the buckle-side engaging portion, the engagement preventing member, the drive source, and the control device are provided within the buckle case.

3. the engagement preventing member has a preventing body that can interfere with the tongue plate inserted into the insertion port, 3. The seat belt device according to claim 2, wherein the blocking body in the engagement preventing position is positioned by the drive source at a location where it interferes with the tongue plate before the tongue side engaging portion engages with the buckle side engaging portion, and the blocking body in the engagement allowing position is positioned by the drive source at a location where it does not interfere with the tongue plate until the tongue side engaging portion engages with the buckle side engaging portion.

4. The seat belt device according to claim 3, wherein the blocking body at the engagement blocking position is positioned by the drive source at a position forward of the buckle side engaging portion in the insertion direction of the tongue plate.

5. 5. The seat belt device according to claim 4, wherein the blocking body in the engagement permission position is positioned by the drive source at a location on the opposite side of the buckle side engagement portion from the insertion port, which is further back in the insertion direction than the buckle side engagement portion.

6. 6. The seat belt device according to claim 3, wherein the engagement preventing member further includes an elastic body that generates a reaction force against the external force from the tongue plate to the blocking body that moves along the insertion direction of the tongue plate due to the external force from the tongue plate.

7. the buckle has a buckle case that forms a receptacle into which the tongue plate is inserted, the tongue-side engaging portion is a through-hole that penetrates the tongue plate in a plate thickness direction, the buckle-side engaging portion is an engaging protrusion that is provided in the buckle case and that is capable of advancing from a non-engaging position that is positioned outside the through hole toward an engaging position that is positioned within the through hole and engages with the through hole when the tongue plate is inserted into the insertion opening, the engagement prevention member has a fixing body that can fix the engagement protrusion at the non-engagement position, 2. The seat belt device according to claim 1, wherein the fixed body in the engagement prevention position is positioned by the drive source at a location where the engagement protrusion is fixed to the non-engagement position, and the fixed body in the engagement permission position is positioned by the drive source at a location where the engagement protrusion can advance from the non-engagement position toward the engagement position.

8. the buckle has a buckle case that forms a receptacle into which the tongue plate is inserted, the tongue-side engaging portion is a through-hole that penetrates the tongue plate in a plate thickness direction, the buckle-side engaging portion is an engaging protrusion that is provided in the buckle case and that is capable of advancing from a non-engaging position that is positioned outside the through hole toward an engaging position that is positioned within the through hole and engages with the through hole when the tongue plate is inserted into the insertion opening, the engagement prevention member has a blocking body that can interfere with the engagement protrusion when the tongue plate is inserted into the insertion port, The seat belt device according to claim 1, wherein the blocking body in the engagement prevention position is positioned by the drive source at a location that blocks at least a portion of the through hole, and the blocking body in the engagement permission position is positioned by the drive source at a location that opens the through hole.

9. A seat belt device according to any one of claims 1, 7 and 8; a vehicle body in which the driver's seat provided with the seat belt device is disposed; The safety frame provided on the vehicle body; a frame posture detection device that detects a state in which the safety frame is in the tilted posture; Equipped with The control device of the seat belt device controls the operation of the drive source based on a signal from the frame attitude detection device.

10. The vehicle further includes a seating detection device that detects a state in which a driver is seated in the driver's seat of the vehicle body, 10. The work vehicle according to claim 9, wherein the control device in the seat belt device controls the operation of the drive source based on signals from the seating detection device and the frame posture detection device so as to position the engagement prevention member in the engagement prevention position when the driver is seated in the driver's seat and the safety frame is in the reclined posture.

11. A direction indicator provided on the safety frame; a power source for operating the turn signal; indicator wiring connecting the power supply and the direction indicator; a seat belt drive wiring branching from the indicator wiring and connected to the drive source and the control device, for supplying electric power as power to the drive source and the control device; The work vehicle according to claim 9, further comprising:

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