Work vehicles

Abstract

The present invention provides a work vehicle capable of lowering its cargo bed even in a power loss state where power cannot be supplied from the power source. [Solution] The work vehicle 10 comprises a loading platform 14 for loading and raising / lowering objects to be transported, a loading platform drive unit 72 which has a drive valve 74 that is operated by hydraulic pressure supplied from an operating hydraulic pressure supply source using power supplied from a power source and controls the drive hydraulic pressure by operating the drive valve 74 to raise and lower the loading platform 14, and a loading platform lowering unit 52 which has a lowering valve 54 that is connected to and operated by the loading platform drive unit 72 and controls the drive hydraulic pressure of the loading platform drive unit 72 by operating the lowering valve 54 to lower the loading platform 14.

Description

Technical Field

[0001] The present invention relates to a work vehicle having a loading platform portion that loads and raises and lowers a load object.

Background Art

[0002] As a work vehicle, a carrier having a vessel as a loading platform portion that loads and raises and lowers earth and sand or the like as a load object is known (for example, see Patent Document 1). In such a carrier, the vessel is raised and lowered by operating a control valve as a driving valve to control the driving hydraulic pressure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a work vehicle, when the driving valve is operated by the hydraulic pressure supplied from the hydraulic pressure supply source using the power supplied from the power source, in a power loss state where power cannot be supplied from the power source, the driving valve cannot be operated, so the loading platform portion cannot be lowered.

[0005] An object of the present invention is to provide a work vehicle capable of lowering the loading platform portion even in a power loss state where power cannot be supplied from the power source.

Means for Solving the Problems

[0006] One aspect of the present invention is a work vehicle comprising: a loading platform for loading and raising / lowering objects to be transported; a loading platform drive unit having a drive valve that is operated by hydraulic pressure supplied from an hydraulic pressure supply source using power supplied from a power source, and raising and lowering the loading platform by controlling the drive hydraulic pressure by operating the drive valve; and a loading platform lowering unit having a lowering valve connected to and operated by the loading platform drive unit, and lowering the loading platform by controlling the drive hydraulic pressure of the loading platform drive unit by operating the lowering valve. [Effects of the Invention]

[0007] In this invention, the cargo bed can be lowered even in a power loss state where power cannot be supplied from the power source. [Brief explanation of the drawing]

[0008] [Figure 1] A perspective view showing a carrier of one embodiment of the present invention. [Figure 2] A schematic diagram showing a vessel drive mechanism and vessel lowering device of one embodiment of the present invention. [Figure 3] A perspective view showing the configuration of a vessel descent device and its surrounding area according to one embodiment of the present invention. [Figure 4] A partially exploded perspective view showing the configuration of a vessel descent device and its surrounding area according to one embodiment of the present invention. [Figure 5] A partially exploded side view showing the configuration of a vessel lowering device and its surroundings according to one embodiment of the present invention. [Figure 6] A perspective view showing the rotational operation of a stop valve according to one embodiment of the present invention. [Figure 7] A partially exploded perspective view showing the rotational operation of a stop valve according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] An embodiment of the present invention will be described below with reference to Figures 1 to 7.

[0010] Referring to Figure 1, the carrier 10 as a work vehicle in this embodiment will be described. As shown in Figure 1, the carrier 10 has a frame 12 as its main body. A vessel 14, which serves as a loading platform, is provided on the frame 12 of the carrier 10. The vessel 14 is positioned on the upper side of the carrier 10 in the vertical direction and on the rear side of the carrier 10 in the front-rear direction. The vessel 14 can carry loads of soil and sand as the object to be transported. The vessel 14 is movable up and down, and in this embodiment, the entire vessel 14 can rotate in the vertical direction of the carrier 10 around a pivot axis P that extends in the left-right direction of the carrier 10 at the rear end of the vessel 14.

[0011] A pair of crawlers 16, which serve as the running gear, are mounted on the frame 12 of the carrier 10. The pair of crawlers 16 are positioned on the right and left sides of the carrier 10, respectively, in the left-right direction. The crawlers 16 are positioned below the vessel 14 in the vertical direction of the carrier 10, and extend in the front-rear direction of the carrier 10, excluding the front and rear ends of the carrier 10, and extending in front of the vessel 14. The crawlers 16 have continuous tracks, and the carrier 10 moves by rotating the continuous tracks in contact with the ground. As a result, mud and other debris from the ground will adhere to the crawlers 16.

[0012] A cockpit 18, which serves as the control room, is provided on the frame 12 of the carrier 10. The cockpit 18 is located in front of the vessel 14 in the longitudinal direction of the carrier 10, above the crawler 16 in the vertical direction of the carrier 10, and on the left side in the lateral direction of the carrier 10. An operator can enter and exit the cockpit 18, and the operator controls the carrier 10 from within the cockpit 18.

[0013] On the frame 12 of the carrier 10, a step 22 as a tread portion is provided. The step 22 is arranged on the left side of the carrier 10, which is the same side as the cab 18 in the left - right direction of the carrier 10, at the front end portion in front of the crawler 16 in the front - rear direction of the carrier 10, and below the cab 18 in the up - down direction of the carrier 10. The step 22 serves as a tread for the operator to board and alight from the cab 18.

[0014] On the frame 12 of the carrier 10, an engine room 42 is provided. The engine room 42 is arranged in front of the vessel 14 in the front - rear direction of the carrier 10, above the crawler 16 in the up - down direction of the carrier 10, and on the right side opposite to the cab 18 in the left - right direction of the carrier 10. An engine as a power source is housed in the engine room 42.

[0015] On the frame 12 of the carrier 10, a vessel lowering device 52 as a loading platform lowering part is provided. The vessel lowering device 52 is arranged at the front end portion in front of the vessel 14 and the crawler 16 and on the same front side as the cab 18 in the front - rear direction of the carrier 10, on the left side which is the same side as the cab 18 in the left - right direction of the carrier 10, and below the cab 18 in the up - down direction of the carrier 10.

[0016] Referring to FIG. 2, the vessel drive mechanism 72 and the vessel lowering device 52 as the loading platform drive part of the present embodiment will be described.

[0017] As shown in FIG. 2, the vessel drive mechanism 72 is a hydraulic mechanism for driving the vessel 14 up and down, and has a control valve 74 as a drive valve. The control valve 74 is switchable between a neutral state for maintaining the vertical position of the vessel 14, an upward drive state for raising the vessel 14, and a downward drive state for lowering the vessel 14.

[0018] Specifically, the vessel drive mechanism 72 has a vessel cylinder 76 that raises and lowers the vessel 14 by extending and retracting. The vessel cylinder 76 has a bottom-side oil chamber 78a and a rod-side oil chamber 78b, and the bottom-side oil chamber 78a and the rod-side oil chamber 78b are hydraulically connected to the bottom-side hydraulic circuit 82a and the rod-side hydraulic circuit 82b, respectively. Furthermore, the vessel drive mechanism 72 has a drive pump 84 and a hydraulic tank 86 that supply drive hydraulic pressure. In the neutral position, the control valve 74 does not connect the drive pump 84 and the hydraulic tank 86 to either the bottom-side hydraulic circuit 82a or the rod-side hydraulic circuit 82b. In the upward drive state, the control valve 74 connects the drive pump 84 to the bottom hydraulic circuit 82a and the rod hydraulic circuit 82b to the hydraulic tank 86, supplying the drive hydraulic pressure from the drive pump 84 to the bottom oil chamber 78a via the bottom hydraulic circuit 82a, and releasing the hydraulic pressure from the rod oil chamber 78b to the hydraulic tank 86 via the rod hydraulic circuit 82b, thereby extending the vessel cylinder 76 and raising the vessel 14. In the downward drive state, the control valve 74 connects the drive pump 84 to the rod hydraulic circuit 82b and the bottom hydraulic circuit 82a to the hydraulic tank 86, supplying the drive hydraulic pressure from the drive pump 84 to the rod oil chamber 78b via the rod hydraulic circuit 82b, and releasing the hydraulic pressure from the bottom oil chamber 78a to the hydraulic tank 86 via the bottom hydraulic circuit 82a, thereby retracting the vessel cylinder 76 and lowering the vessel 14.

[0019] The control valve 74 is switched between the neutral state, the upward drive state, and the downward drive state by operating the lifting lever 96 inside the cockpit 18.

[0020] That is, the vessel drive mechanism 72 has a hydraulic pump 88 as a hydraulic pressure supply source, and the hydraulic pump 88 is hydraulically connected to the raise port 92a and the lower port 92b of the control valve 74 via a lift operation lever 96. When the lift operation lever 96 is disposed at the neutral position, it does not supply pilot pressure as hydraulic pressure to the raise port 92a and the lower port 92b, and sets the control valve 74 to the neutral state. When the lift operation lever 96 is disposed at the raise operation position, it supplies pilot pressure to the raise port 92a, and switches the control valve 74 to the raise drive state. When the lift operation lever 96 is disposed at the lower operation position, it supplies pilot pressure to the lower port 92b, and switches the control valve 74 to the lower drive state.

[0021] The hydraulic pump 88 is driven using the power from the engine to supply pilot pressure to the control valve 74. Therefore, when the hydraulic pump 88 enters a power loss state in which power cannot be supplied from the engine due to a failure of the engine or the like, the hydraulic pump 88 cannot be driven, pilot pressure cannot be supplied to the control valve 74, and the control valve 74 cannot be switched to the lower drive state. For this reason, in the vessel drive mechanism 72, when the vessel 14 is in the raised state and enters a power loss state in which power cannot be supplied from the engine, the vessel 14 cannot be lowered.

[0022] The vessel lowering device 52 is a hydraulic device for lowering the vessel 14 in the event of a power loss where power cannot be supplied from the engine, and has a stop valve 54 as a lowering valve. The stop valve 54 is interposed in a release hydraulic circuit 94 that hydraulically connects the bottom oil chamber 78a of the vessel cylinder 76 of the vessel drive mechanism 72 to the hydraulic tank 86. When the stop valve 54 is in the closed state, it blocks the release hydraulic circuit 94 and does not affect the raising and lowering drive of the vessel 14 by the vessel drive mechanism 72. When the stop valve 54 is operated to the open state, it releases hydraulic pressure from the bottom oil chamber 78b of the vessel cylinder 76 of the vessel drive mechanism 72 to the hydraulic tank 86 via the release hydraulic circuit 94, and as a result the vessel cylinder 76 is retracted by the weight of the vessel 14, and the vessel 14 is lowered.

[0023] The stop valve 54 can be operated without using power supplied from the engine. Therefore, in the vessel lowering device 52, even if a power loss occurs where power cannot be supplied from the engine when the vessel 14 is in the raised position, the vessel 14 can be lowered by operating the stop valve 54.

[0024] The configuration of the vessel lowering device 52 and its surroundings will be described with reference to Figures 3 to 5. As shown in Figures 3 to 5, the vessel lowering device 52 is positioned on the carrier 10, in the left-right direction of the carrier 10, inward from the left side surface of the frame 12, and is covered by a cover member 56 that forms part of the left side surface of the frame 12, and is located inside the frame 12. The cover member 56 of the frame 12 has a notch 58 formed as an opening. The notch 58 has an elongated hole shape that extends in the vertical direction of the carrier 10. The stop valve 54 of the vessel lowering device 52 is accessible through the notch 58. The stop valve 54 can be opened and closed by rotating it around a predetermined axis of rotation Q. The axis of rotation Q of the stop valve 54 intersects with the access direction to the stop valve 54 via the notch 58. In this embodiment, the access direction is parallel to the left-right direction of the carrier 10, and the axis of rotation Q of the stop valve 54 extends in the front-rear direction of the carrier 10, substantially perpendicular to the access direction. Furthermore, the Carrier 10 comes equipped with a wrench as part of its onboard tool kit.

[0025] As described above, step 22 serves as a step for the operator to get in and out of the cockpit 18. The arrangement of the cockpit 18, step 22, and vessel lowering device 52 in the carrier 10 is as described above, and step 22 and vessel lowering device 52 are positioned in close proximity in the carrier 10. Step 22 has a step member 24 as a stepping member to support the operator's feet, and a step mounting seat 32 as a mounting member for attaching the step member 24 to the frame 12.

[0026] The step member 24 is formed by a scaffolding member 26, and a front support member 28a and a rear support member 28b. The scaffolding member 26 extends in the front-rear direction of the carrier 10. The front support member 28a and the rear support member 28b are positioned in the front and rear of the scaffolding member 26 in the front-rear direction of the carrier 10, respectively, and extend in the vertical direction of the carrier 10. The front end and rear end of the scaffolding member 26 are connected to the lower ends of the front support member 28a and the rear support member 28b, respectively. The step mounting seat 32 has a front mounting member 34a and a rear mounting member 34b. One end of the front mounting member 34a is connected to the upper end of the front support member 28a of the step member 24, and the other end of the front mounting member 34a is connected to the frame 12. Similarly, one end of the rear mounting member 34b is connected to the upper end of the rear support member 28b of the step member 24, and the other end of the rear mounting member 34b is connected to the frame 12.

[0027] Regarding the rear mounting member 34b, a first portion 36a extends upward from one end of the rear mounting member 34b, which is connected to the upper end of the rear support member 28b of the step member 24. Subsequently, a second portion 36b bends and extends diagonally upward and rearward, followed by a third portion 36c bends and extends upward. The other end of the rear mounting member 34b is connected to the frame 12. The vessel lowering device 52 is positioned in front of the second portion 36b and the third portion 36c of the rear mounting member 34b. In this way, the step member 24 is positioned in the same location as in the previous case where the vessel lowering device 52 is not installed.

[0028] Next, we will explain the operation of the stop valve 54 of the vessel lowering device 52 on the carrier 10. If, while operating the carrier 10, the vessel 14 is raised and a power loss occurs due to engine failure or other reasons preventing power from being supplied from the engine, the operator in the cockpit 18 cannot lower the vessel 14. If the vessel 14 is kept in the raised position, there is a risk that the soil and other materials loaded on the vessel 14 may slide off or hinder the movement of the carrier 10 by towing it; therefore, it is preferable to keep the vessel 14 lowered.

[0029] When the operator in the control room 18 operates the stop valve 54 of the vessel lowering device 52, the operator disembarks from the control room 18 using the step 22 as a stepping stone and moves to the vicinity of the stop valve 54. Here, the vessel lowering device 52 is located at the front end of the carrier 10, which is the same front side as the control room 18 in the longitudinal direction of the carrier 10; on the left side of the carrier 10, which is the same side as the control room 18 in the lateral direction of the carrier 10; and below the control room 18 in the vertical direction of the carrier 10. Therefore, it is possible to easily move from the control room 18 to the vicinity of the stop valve 54. If there are workers other than the operator around the carrier 10, those workers may operate the stop valve 54.

[0030] Next, the stop valve 54 is rotated to open it. In this embodiment, as shown in Figures 6 and 7, the stop valve 54 is accessed and held through a notch 58 in the frame 12 using a wrench 62, which is an on-board tool. The wrench 62 is then rotated vertically on the carrier 10 around the rotation axis Q of the stop valve 54, thereby rotating the stop valve 54 to open it. This lowers the vessel 14. After the vessel 14 has been lowered, the stop valve 54 is rotated to close it. In this way, the stop valve 54 can be easily rotated using a wrench 62, which is a general-purpose, relatively inexpensive, and suitable on-board tool. Furthermore, since the wrench 62 is an on-board tool, it can be prepared quickly and easily when rotating the stop valve 54.

[0031] The vessel lowering device 52 is positioned at the front end of the carrier 10, in the longitudinal direction of the carrier 10, ahead of the vessel 14. This allows the stop valve 54 to be operated from a distance from the lowering vessel 14, enabling safe operation of the stop valve 54. Furthermore, because the vessel lowering device 52 is positioned at the front end of the carrier 10, in the longitudinal direction of the carrier 10, ahead of the crawler 16, the crawler 16 does not obstruct the operation of the stop valve 54. This allows for easy access to the stop valve 54, enabling operation in a comfortable position. Additionally, it prevents the operator or worker operating the stop valve 54 from being contaminated by mud or other debris adhering to the crawler 16.

[0032] The stop valve 54 of the vessel drive mechanism 72 must be kept closed in normal conditions other than power loss, because when it is open, the vessel drive mechanism 72 cannot raise the vessel 14. However, there is a possibility that the stop valve 54 may be open even in normal conditions due to forgetting to close it after opening it, or due to incorrect operation of the stop valve 54 to open it. For this reason, the operator must check whether the stop valve 54 is closed each time they board or alight from the cockpit 18. Here, since the vessel lowering device 52 is positioned on the carrier 10 in relation to the cockpit 18 as described above, the operator can easily check whether the stop valve 54 is closed when boarding or alighting from the cockpit 18.

[0033] Operators, workers, etc. may move near the vessel lowering device 52 even when not operating the stop valve 54 of the vessel lowering device 52. In such cases, the vessel lowering device 52 is positioned on the carrier 10, inside the left side of the outer surface of the frame 12 in the left-right direction of the carrier 10, and is covered by a cover member 56 that forms part of the left side of the frame 12, and is positioned inside the frame 12. Therefore, it is prevented from the operator's, workers', or other persons' bodies, clothing, etc. getting caught on the vessel lowering device 52.

[0034] In the carrier 10, the vessel lowering device 52 and the step 22 are located in close proximity. However, the position of the step member 24 that supports the operator's feet in the step 22 is the same as in the previous case where the carrier 10 was not equipped with the vessel lowering device 52. Therefore, the operator can easily get in and out of the cockpit 18 with the same familiar movements as in the previous case.

[0035] The characteristic disclosures of this embodiment described above can be summarized as follows:

[0036] The first disclosure is a work vehicle comprising: a loading platform for loading and raising / lowering objects to be transported; a loading platform drive unit having a drive valve that is operated by hydraulic pressure supplied from an hydraulic pressure supply source using power supplied from a power source, and which raises and lowers the loading platform by controlling the drive hydraulic pressure by operating the drive valve; and a loading platform lowering unit having a lowering valve that is connected to and operated by the loading platform drive unit, and which lowers the loading platform by controlling the drive hydraulic pressure of the loading platform drive unit by operating the lowering valve. This disclosure indicates that even in a power loss state where power cannot be supplied from the power source, the cargo bed can be lowered by operating the lowering valve.

[0037] The second disclosure is that the work vehicle described in the first disclosure is such that the lowering section of the cargo bed is located in front of the cargo bed section in the longitudinal direction of the work vehicle.

[0038] This disclosure allows for the safe operation of the lowering valve by enabling it to be operated from a distance from the lowering platform.

[0039] The third disclosure is the work vehicle of the first disclosure, further comprising a running section having an endless track that is grounded and rotated to propel the work vehicle, and the loading platform lowering section being positioned in front of the running section in the longitudinal direction of the work vehicle.

[0040] In this disclosure, the running gear does not obstruct the operation of the lowering valve, allowing for easy access to the lowering valve and operation in a comfortable position. Furthermore, the running gear is prevented from becoming contaminated by mud or other debris.

[0041] The fourth disclosure is the work vehicle of the first disclosure, further comprising a control unit for the operator to board and alight, the control unit being located on one side in the left-right direction of the work vehicle, and the cargo bed lowering unit being located on the same one side as the control unit in the left-right direction of the work vehicle.

[0042] This disclosure allows the pilot to easily move from the control panel to the vicinity of the descent valve when operating it, and also allows the pilot to easily check the status of the descent valve when getting on or off the control panel.

[0043] The fifth disclosure is the work vehicle of the first disclosure, further comprising a main body on which the cargo bed is provided, and the cargo bed lowering section provided on the main body and positioned inward from the outer surface of the main body.

[0044] This disclosure ensures that even when people are moving near the lowering section of the cargo bed, their bodies, clothing, etc., will not get caught in the lowering section.

[0045] The sixth disclosure is a work vehicle of the fifth disclosure, wherein the cargo bed lowering section is located inside the main body, the main body has an opening, and the lowering valve is accessed and operated through the opening.

[0046] This disclosure makes it possible to access and operate the lowering valve of the cargo bed lowering section located inside the main body through an opening in the main body.

[0047] The seventh disclosure is the work vehicle of the sixth disclosure, wherein the lowering valve is rotated about a predetermined axis of rotation, and the axis of rotation of the lowering valve intersects with the access direction that accesses the lowering valve through the opening.

[0048] This disclosure describes a system that allows for easy rotation of the lowering valve using a general-purpose, relatively inexpensive wrench suitable for use as an on-board tool.

[0049] The eighth disclosure is the work vehicle of the sixth disclosure, which accesses the lowering valve through the opening using a tool and operates the lowering valve, the tool being an on-board tool provided on the work vehicle.

[0050] This disclosure states that the lowering valve can be operated using the on-board tools provided in the work vehicle, making it possible to quickly and easily prepare the tools when operating the lowering valve.

[0051] The ninth disclosure is the work vehicle of the fourth disclosure, further comprising: a main body on which the cargo bed, the cargo bed lowering section, and the control unit are provided; and a stepping stool provided on the main body which serves as a stepping stool for the operator to get on and off the control unit, wherein the stepping stool has a stepping member for supporting the operator's feet and a mounting member provided on the main body to which the stepping member is attached.

[0052] In this disclosure, even when the loading platform lowering section is positioned close to the stepping platform, the loading platform lowering section can be positioned using mounting members while maintaining the position of the stepping platform in the same position as when the loading platform lowering section is not used. This allows the operator to easily get on and off the control unit with the same familiar movements as when the loading platform lowering section is not used. [Explanation of symbols]

[0053] 10...Carrier 12...Frame 14...Vessel 16...Crawler 18...Cockpit 22...Step 24...Step member 26...Scaffolding member 28a...Front support member 28b...Rear support member 32...Step mounting base 34a...Front mounting member 34b...Rear mounting member 36a...First part 36b...Second part 36c...Third part 42...Engine compartment 52...Vessel lowering device 54...Stop valve 56...Cover component 58...Notch 62...Spanner 72...Vessel drive mechanism 74...Control valve 76...Vessel cylinder 78a...Bottom oil chamber 78b…Rod-side oil chamber 82a…Bottom-side hydraulic circuit 82b…Rod-side hydraulic circuit 84...Drive pump 86...Hydraulic tank 88...Accelerating pump 92a...Lifting port 92b...Lowering port 94...Release hydraulic circuit 96...Lifting lever P...Rotating shaft Q... axis of rotation

Claims

1. It is a work vehicle, A loading platform for transporting and raising / lowering the cargo, A cargo bed drive unit has a drive valve that is operated by hydraulic pressure supplied from an hydraulic pressure supply source using power supplied from a power source, and raises and lowers the cargo bed by controlling the drive hydraulic pressure by operating the drive valve, A cargo bed lowering unit has a lowering valve connected to and operated by the cargo bed drive unit, and lowers the cargo bed by controlling the drive hydraulic pressure of the cargo bed drive unit by operating the lowering valve, A work vehicle equipped with the following.

2. The aforementioned cargo bed lowering section is positioned in front of the cargo bed section in the longitudinal direction of the work vehicle. A work vehicle according to claim 1.

3. The aforementioned work vehicle further comprises a running section having an endless track that is grounded and rotated to propel the work vehicle, The aforementioned cargo bed lowering section is positioned in front of the aforementioned driving section in the longitudinal direction of the work vehicle. A work vehicle according to claim 1.

4. The aforementioned work vehicle further comprises a control section for the operator to board and disembark, The control unit is located on one side of the work vehicle in the left-right direction. The cargo bed lowering section is located on the same side as the control unit in the left-right direction of the work vehicle. A work vehicle according to claim 1.

5. The aforementioned work vehicle further comprises a main body on which the cargo bed is provided, The aforementioned cargo bed lowering section is provided on the main body and is positioned inward from the outer surface of the main body. A work vehicle according to claim 1.

6. The aforementioned cargo bed lowering section is located inside the main body. The main body has an opening, and the lowering valve is accessed through the opening and operated. The work vehicle according to claim 5.

7. The lowering valve is rotated around a predetermined axis of rotation, The rotation axis of the lowering valve intersects with the access direction that accesses the lowering valve through the opening. The work vehicle according to claim 6.

8. Access the lowering valve through the opening using a tool and operate the lowering valve, The aforementioned tool is an on-board tool installed in the aforementioned work vehicle. The work vehicle according to claim 6.

9. The aforementioned work vehicle further comprises a main body on which the cargo bed, the cargo bed lowering section, and the control section are provided, and a step section provided on the main body which serves as a step for the operator to get on and off the control section, The footrest portion comprises a footrest member that supports the operator's feet, and a mounting member provided on the main body to which the footrest member is attached. The work vehicle according to claim 4.

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