Work vehicles

Abstract

This design allows for a more compact configuration that stops the flow of hydraulic fluid when the external hydraulic valve is not operating, enabling the work implement to be held in place, while allowing the hydraulic fluid to flow when the external hydraulic valve is operating. [Solution] An external hydraulic valve unit 60 operates a valve spool 70 in conjunction with the operation of operating tools 30 and 34 to operate hydraulic equipment 17 and 18 mounted on the work machine 14, and a check valve unit 90 has a check valve 93 that stops the hydraulic fluid from flowing from the hydraulic equipment 17 and 18 to the port 63 of the external hydraulic valve unit 60, and a connector 100 is provided to connect the valve spool 70 and the check valve unit 90 so that the opening and closing state of the oil passage 98 for the hydraulic fluid flowing from the hydraulic equipment 17 and 18 to the port 63 of the external hydraulic valve unit 60 is linked to the movement of the valve spool 70.

Description

Technical Field

[0001] The present invention relates to a work vehicle such as an agricultural tractor.

Background Art

[0002] There is a known work vehicle in which a working machine such as a front loader is attached to a work vehicle such as an agricultural tractor and the working machine is moved by an external hydraulic operation lever or a JOY stick lever (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When operating an external hydraulic operation lever or a JOY stick lever, it is configured to be operable through an external hydraulic valve. When not in operation, a pilot check valve (see FIG. 7) is installed to stop the hydraulic oil and hold the working machine, and when in operation, the hydraulic oil flows. However, since it is retrofitted according to the requirements of the working machine, a large-sized pilot check valve occupies space.

[0005] Therefore, an object of the present invention is to more compactly realize a configuration in which the flow of hydraulic oil is stopped to hold the working machine when the external hydraulic valve is not in operation, and the hydraulic oil flows when the external hydraulic valve is in operation.

Means for Solving the Problems

[0006] Therefore, the work vehicle according to the invention has taken the following technical means to solve the above problems.

[0007] The system includes a work implement (14) mounted on a vehicle body (10), operating tools (30, 34) for operating the work implement (14), an external hydraulic valve unit (60) whose valve spool (70) operates in conjunction with the operation of the operating tools (30, 34) to operate hydraulic equipment (17, 18) mounted on the work implement (14), and a check valve unit (90) having a check valve (93) that stops the hydraulic fluid from flowing from the hydraulic equipment (17, 18) to the port (63) of the external hydraulic valve unit (60), and a connector (100) that connects the valve spool (70) and the check valve unit (90) so that the opening and closing state of the oil passage (98) for the hydraulic fluid flowing from the hydraulic equipment (17, 18) to the port (63) of the external hydraulic valve unit (60) is linked to the movement of the valve spool (70). [Effects of the Invention]

[0008] According to the present invention, a more compact configuration can be achieved that allows the hydraulic fluid flow to be stopped when the external hydraulic valve is not operating, thereby enabling the work implement to be held in place, while allowing the hydraulic fluid to flow when the external hydraulic valve is operating. [Brief explanation of the drawing]

[0009] [Figure 1] Left side view of an agricultural tractor according to an embodiment of the present invention [Figure 2] Plan view of the cabin of an agricultural tractor according to an embodiment of the present invention [Figure 3] Enlarged plan view of the right side dashboard portion of an agricultural tractor according to an embodiment of the present invention. [Figure 4] Perspective view of the interior of the cabin of an agricultural tractor according to an embodiment of the present invention, viewed from the front left. [Figure 5] Perspective view of the rear of the cabin of an agricultural tractor according to an embodiment of the present invention. [Figure 6] Perspective view of the cabin of an agricultural tractor according to an embodiment of the present invention, viewed from the front. [Figure 7] Diagram showing the configuration of an external hydraulic valve in a conventional agricultural tractor. [Figure 8]Developed diagram of the external hydraulic valve of an agricultural tractor according to an embodiment of the present invention. [Figure 9] Partial enlarged view of a check valve unit for an agricultural tractor according to an embodiment of the present invention. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. In this specification, the left and right sides in the forward direction of the work vehicle will be referred to as left and right, respectively, and the front and rear will be referred to as front and rear, respectively.According to embodiments of the present invention, an agricultural machine tractor, which is an example of a work vehicle, will be described below as an example.

[0011] Figure 1 is a left side view of the agricultural tractor according to this embodiment. Figure 2 shows a plan view of the cabin of the agricultural tractor according to this embodiment, and Figure 3 shows an enlarged plan view of the right side dashboard. Figure 4 is a perspective view of the interior of the cabin of the agricultural tractor according to this embodiment, viewed from the front left, Figure 5 is a perspective view of the cabin, viewed from the rear, and Figure 6 is a perspective view of the cabin, viewed from the front.

[0012] As shown in Figure 1, the tractor 10 of this embodiment is configured with a pair of drive rear wheels 12 mounted on the rear of the vehicle body and left and right front wheels 11, which are steered by a steering wheel 20, mounted on the front. The tractor 10 has a cabin that surrounds the driver's seat 21 equipped with a steering wheel 20, and the front side of the cabin is covered with a bonnet 13. Inside the bonnet, the engine and its auxiliary components, namely the radiator, oil cooler, air conditioning condenser, intercooler, air cleaner, battery, etc., are installed.

[0013] As shown in Figure 1, the tractor 10 is equipped with a front loader 14 on the front of the vehicle body.

[0014] The front loader 14 includes a pair of left and right side frames 19 attached to both sides of the vehicle body of the tractor 10, a main frame 16 pivotally connected to the upper part of the side frame 19 and supported so as to be vertically swingable, and a bucket 15 pivotally connected to the tip side of the main frame 16 and supported so as to be vertically swingable. Further, a main frame swing cylinder 18 that can be operated in a telescopic manner is connected between the base of the side frame 19 and the central part of the main frame 16, and a bucket swing cylinder 17 that controls the swing of the bucket 15 is connected to the upper front part of the main frame 16.

[0015] Note that the tractor 10 is an example of the work vehicle of the present invention, and the front loader 14 is an example of the working machine of the present invention.

[0016] Further, the tractor 10 of the present embodiment can be attached to a three-point link mechanism configured with a working machine (not shown) such as a rotary tiller at the rear part of the machine body so as to be able to be lifted and lowered, and can perform ground operations.

[0017] Next, the arrangement of each operating tool in the cab of the tractor 10 of the present embodiment will be described.

[0018] The driver's seat 21 arranged at the center of the cab has an armrest 26 on the left side. On both sides of the driver's seat 21, a right-side dashboard 22 and a left-side dashboard 23 are erected.

[0019] A step is provided at the upper part of the right-side dashboard 22, and it has two substantially horizontal surfaces, an upper surface 24 and a lower surface 25. As shown in FIG. 4, the upper surface 24 is formed at the rear outer side of the upper part of the right-side dashboard 22, and the lower surface 25 is formed at the front inner side of the upper part of the right-side dashboard 22.

[0020] Operating tools for operating the working machine are concentratedly arranged on these upper surface 24 and lower surface 25.

[0021] A triple external hydraulic lever 34 is arranged on the upper surface 24.

[0022] A position lever 31 is located at the front end of the lower surface 25, and a PTO selector switch 32 and a tilling depth adjustment dial 33 are located near the rear end of the position lever 31. Further behind the PTO selector switch 32 and tilling depth adjustment dial 33, a PTO on / off switch 35 is located. The PTO selector switch 32 is a switch that switches between an automatic mode in which the PTO is turned on and off in conjunction with the vehicle status, and a manual mode in which the PTO is turned on and off only by the PTO on / off switch 35.

[0023] As shown in Figure 3, a lower position adjustment dial 37 is provided at the front end of the base of the position lever 31, and an upper position adjustment dial 38 is provided at the rear end of the base of the position lever 31.

[0024] The position lever 31 is a lever that controls the raising and lowering of the work implement. The rear position controls "raising," and the front position controls "lowering," allowing the work implement to be raised or lowered during machine rotation, etc. The lowering position adjustment dial 37 and the raising position adjustment dial 38 adjust the forward and backward range of motion of the position lever 31, thereby regulating the height range in which the work implement moves up and down.

[0025] Furthermore, the PTO on / off switch 35 is a dial type, so it will not malfunction even if part of the operator's body touches it. Also, because it is positioned closest to the operator's seat 21 behind the tillage depth adjustment dial 33, the operator can operate it immediately, making it effective in terms of safety.

[0026] By placing frequently used controls on the lower surface 25, which is close to the driver's seat 21, the operator can operate the controls smoothly.

[0027] Furthermore, the JOY stick lever 30 is positioned in front of the right-side dashboard 22, in a location that is easily operated with the right hand by an operator seated in the driver's seat 21.

[0028] On the other hand, the controls for the driving system are concentrated between the driver's seat 21 and the right-side dashboard 22.

[0029] The main shift lever 40 is positioned between the driver's seat 21 and the right-side dashboard 22, in a location easily accessible with the right hand. Behind the main shift lever 40, the sub-shift lever 41 and the creep speed lever 42 are positioned in order. The sub-shift lever 41 can be fixed in any position, and the travel speed of the tractor 10 can be maintained at a constant level depending on the position of the lever.

[0030] The PTO selector switch 32 is located on the lower surface 25 of the right-side dashboard 22, in a position close to the main shift lever 40.

[0031] In this way, by concentrating the operating tools for the work equipment on the right-side dashboard 22 and concentrating the operating tools for the drive system between the driver's seat 21 and the right-side dashboard 22, the operator can easily understand the location of the operating tools and operate them smoothly.

[0032] The JOY stick lever 30 is an example of the loader lever of the present invention, and the main change lever 40 is an example of the main gear shift lever of the present invention. Also, the right-side dashboard 22 is an example of the side dashboard of the present invention.

[0033] As shown in Figure 4, the JOY stick lever 30 is positioned so that its tip is higher than the seat surface of the driver's seat 21, and the main change lever 40 is also positioned so that its tip is higher than the seat surface of the driver's seat 21.

[0034] Furthermore, although both the JOY Stick Lever 30 and the Main Change Lever 40 are levers that are operated in the forward and backward directions, they are positioned such that when an operator grips the tip of either lever at the closest position between the JOY Stick Lever 30 and the Main Change Lever 40, there is a gap between the hand gripping that lever and the other lever. Therefore, when an operator operates the JOY Stick Lever 30 or the Main Change Lever 40, their body will not accidentally come into contact with the other lever, resulting in incorrect operation.

[0035] Furthermore, instead of arranging the JOY stick lever 30 and the main change lever 40 side by side in the front-to-back direction of the aircraft, they are positioned offset from each other in the left-to-right direction of the aircraft, as shown in Figure 2. This improves operability when frequently operating these levers.

[0036] The accelerator pedal 49 is located on the floor to the right and front of the driver's seat 21.

[0037] Additionally, a 4WD lever 43 is located below and to the right of the driver's seat 21, and a PTO shift lever 36 is located below and to the left of the driver's seat 21. Furthermore, a differential lock pedal 44 is located below and to the right of the driver's seat 21.

[0038] A hazard switch 50 is located to the left front of the steering wheel 20.

[0039] As shown in Figure 5, a center horn 51 is provided in the center of the steering wheel 20. From the perspective of an operator seated in the driver's seat 21, the forward / reverse lever 45 is located to the left rear of the steering wheel 20, and the turn signal lever 52 is located to the right rear of the steering wheel 20. The throttle lever 46 is located to the right front of the steering wheel 20, and the key switch 53 and parking lever 54 are located to the lower right of the steering wheel 20.

[0040] The left and right brake pedals 48 are positioned near the floor, slightly to the right and forward of the driver's seat 21, while the clutch pedal 47 is positioned near the floor, slightly to the left and forward of the driver's seat 21. Additionally, the tilt pedal 55 is positioned near the floor, slightly to the left and below the steering wheel 20.

[0041] In the above description, the 4WD lever 43 and the PTO shift lever 36 are positioned on a surface that rises vertically from the floor below the driver's seat 21 and have a lever shape that extends forward. However, they may also be positioned closer to the side of the driver's seat 21 and have a lever shape that extends upward.

[0042] Figure 7 shows a conventional configuration in which a pilot check valve 80 is connected to an external hydraulic valve unit 60. The external hydraulic valve unit 60 adjusts the supply of hydraulic fluid to the main frame swinging cylinder 18, bucket swinging cylinder 17, and other hydraulic equipment of the work machine of the front loader 14 by using a spool 70 that slides in conjunction with the JOY stick lever 30 and the external hydraulic lever 34. This allows the front loader 14 and other work machines such as a reversible plow to be freely operated by operating the JOY stick lever 30 and the external hydraulic lever 34.

[0043] Hydraulic fluid flows into the external hydraulic valve unit 60 by pushing the first poppet valve 71 from the first port 61. For example, when the JOY stick lever 30 is pushed forward, the valve spool 70 moves in conjunction with it, being pulled out of the body 69. Then the hydraulic fluid flowing in by pushing the first poppet valve 71 from the first port 61 flows to the second port 62, which is connected to the pilot check valve 80. The pressure of the hydraulic fluid flowing from the second port 62 to the fourth port 84 side of the pilot check valve 80 moves the pilot spool 81, pushing the second poppet valve 82 of the pilot check valve 80 and opening the oil passage to the fifth port 85 side. The hydraulic fluid coming out of the fourth port 84 retracts the main frame oscillating cylinder 18, and the hydraulic fluid coming out of the main frame oscillating cylinder 18 enters from the fifth port 85 and is discharged to the tank port 64.

[0044] For example, when the JOY stick lever 30 is not operated, the hydraulic fluid flowing in from the first port 61 through the first poppet valve 71 is stopped by the valve spool 70, so no pressure is generated on the fourth port 84 side, and the second poppet valve 82 is closed by its internal spring. When the front loader 14 is raised, it tries to descend due to its own weight, but the oil passage on the fifth port 85 side is closed by the internal spring and the pressure of the hydraulic fluid flowing into the second poppet valve 82, so it can maintain its raised position without descending.

[0045] For example, when the JOY stick lever 30 is pushed backward, the valve spool 70 slides in conjunction with it, being pushed into the body 69. The pressure generated by the hydraulic fluid flowing to the third port 63 of the external hydraulic valve unit 60 pushes the second poppet valve 82, opening the oil passage to the fifth port 85. The hydraulic fluid exiting the fifth port 85 extends the main frame oscillating cylinder 18, and the hydraulic fluid exiting the main frame oscillating cylinder 18 enters through the fourth port 84 and is discharged to the tank port 64.

[0046] Thus, the conventional pilot check valve 80 was able to prevent the front loader 14 from descending due to its own weight and hold it in the raised position. However, it had the problem of occupying a large space because it required a body 89 that could withstand the pressure of the hydraulic fluid and was connected to both the second port 62 and the third port 63 of the external hydraulic valve unit 60.

[0047] As shown in Figures 8 and 9, the external hydraulic valve unit 60 mounted on the tractor 10 of this embodiment has a check valve unit 90 equipped with a third poppet valve 93 connected to the third port 63. The check valve unit 90, as an example, has a sixth port 96 for discharging hydraulic fluid to the main frame oscillating cylinder 18.

[0048] The third poppet valve 93 of the check valve unit 90 has an oil passage 97 that communicates with the sixth port 96 and the inside of the third poppet valve 93, and an oil passage 98 that communicates with the third port 63 of the external hydraulic valve unit 60 and the inside of the third poppet valve 93. A needle valve 92 inserted into the inside of the third poppet valve 93 is biased by a spring in a direction that closes the oil passage 98. A pin 91 is connected to the end of the needle valve 92 opposite to the oil passage 98. The pin 91 is connected to the valve spool 70 and the plate 100, and the pin 91 and the plate 100 are connected via an elongated hole 101 formed in the plate 100.

[0049] The hole through which the third poppet valve 93 slides is sealed by a plug 94, and an O-ring seat is formed on the sliding part of the plug side, which is sealed by an O-ring 94a. The pin 91 is exposed to the outside by passing through a hole provided in the plug 94. The tip of the pin 91 has a circular engaging portion 91a which engages with a retaining ring 92a attached to the needle valve 92, making it possible to pull out the needle valve 92.

[0050] For example, when the JOY stick lever 30 is pushed forward, the valve spool 70 moves in conjunction, being pulled out of the body 69. This pushes the first poppet valve 71 from the first port 61, causing the hydraulic fluid flowing in to exit from the second port 62, retracting the main frame oscillating cylinder 18 and lowering the front loader 14. As the valve spool 70 slides in the pulling direction, the needle valve 92 connected by the plate 100 also slides in the pulling direction. The hydraulic fluid coming out of the main frame oscillating cylinder 18 flows into the check valve unit 90 from the sixth port 96, and through the oil passage 97 into the third poppet valve 93. Since the needle valve 92 is pulled out and the oil passage 98 is open, the hydraulic fluid is discharged to the tank port 64 through the third port 63. Furthermore, when the pressure on the third port 63 side increases, the third poppet valve 93 is also pushed, causing more hydraulic fluid to be discharged from the tank port 64, thus lowering the front loader 14.

[0051] For example, when the JOY stick lever 30 is not operated, the hydraulic fluid flowing in from the first port 61 by pushing the first poppet valve 71 is stopped by the valve spool 70. The third poppet valve 93 is closed by an internal spring. When the front loader 14 is raised, it tries to descend due to its own weight, but the oil passage on the sixth port 96 side is closed by the pressure of the internal spring and the hydraulic fluid flowing into the third poppet valve 93, so it can remain in the raised position without descending. The needle valve 92 blocks the oil passage 98 by a spring inside the plug 94, so the hydraulic fluid does not flow out to the third port 63 side and is pressed in the direction of closing the third poppet valve 93.

[0052] For example, when the JOY stick lever 30 is pushed backward, the valve spool 70 slides in conjunction with it, pushing into the body 69. The pressure generated by the hydraulic fluid flowing to the third port 63 of the external hydraulic valve unit 60 pushes the third poppet valve 93, opening the oil passage on the sixth port 96 side. The hydraulic fluid exiting the sixth port 96 extends the main frame oscillating cylinder 18, and the hydraulic fluid exiting the main frame oscillating cylinder 18 enters through the second port 62 and is discharged to the tank port 64. The elongated hole 101 in the plate 100 is configured such that when the valve spool 70 is pushed into the body 69, the connection part with the pin 91 slides within the elongated hole 101, so the pin 91 does not move.

[0053] With the above configuration, by connecting the check valve unit 90, which is linked to the withdrawal operation of the valve spool 70, to the third port 63 of the external hydraulic valve unit 60, the front loader 14 can be prevented from descending due to its own weight and can be maintained in the raised position, while also being able to be configured compactly without blocking the second port 62.

[0054] In the above embodiment, a front loader 14 operated by a JOY stick lever 30 was shown as the work implement to be attached, but it is not limited to this, and other work implements may also be a reversible plow with a reversing mechanism, a harrow with a folding mechanism used for puddling work, a rake for collecting hay, or a tedda for spreading hay, which are equipped with hydraulic equipment such as hydraulic cylinders and operated by an external hydraulic lever 34 and an external hydraulic valve unit 60. [Explanation of symbols]

[0055] 10. Tractor (vehicle body) 14. Front loader (work equipment) 17. Bucket swinging cylinder (hydraulic equipment) 18. Cylinder for main frame oscillation (hydraulic equipment) 30 Joy Stick Lever (Control Device) 34. External hydraulic lever (operating device) 60 External Hydraulic Valve Unit 62 Second port (port) 63 Third port (port) 70 Valve Spool 90 Check valve unit 91 pins 92 Needle valve 93. Third poppet valve (check valve) 97 Oil road 98 Oil road 100 Plates (Connectors) 101 Long hole (accommodating mechanism)

Claims

1. A work implement (14) attached to the vehicle body (10), Operating tools (30, 34) for operating the aforementioned work machine (14), An external hydraulic valve unit (60) operates in conjunction with the operation of the aforementioned operating tools (30, 34) to activate the valve spool (70) and the hydraulic equipment (17, 18) mounted on the work machine (14), The system includes a check valve unit (90) having a check valve (93) that stops the hydraulic fluid from flowing from the hydraulic equipment (17, 18) to the port (63) of the external hydraulic valve unit (60), A work vehicle equipped with a connector (100) that connects the valve spool (70) and a check valve unit (90) so that the opening and closing state of the oil passage (98) for the hydraulic fluid that is to flow from the hydraulic equipment (17, 18) to the port (63) of the external hydraulic valve unit (60) is linked to the movement of the valve spool (70).

2. The work vehicle according to claim 1, wherein the check valve unit (90) is connected to one of the multiple ports (62, 63) of the external hydraulic valve unit (60), namely port (63).

3. The work vehicle according to claim 1, wherein the connecting device (100) connects the valve spool (70) and the check valve unit (90) via a connecting mechanism (101).

4. The check valve unit (90) has a check valve (93) which includes oil passages (97, 98) that connect the hydraulic equipment (17, 18) and the port (63) of the external hydraulic valve unit (60), has a needle valve (92) inside the check valve (93) that opens and closes the oil passage (98), and has a pin (91) that opens and closes the needle valve (92). The work vehicle according to claim 3, wherein the connector (100) connects the valve spool (70) and the pin (91), the interlocking mechanism (101) is an elongated hole, and is configured to interlock when the valve spool (70) moves in the direction that opens the oil passage (98) with the needle valve (92), and not interlock when the valve spool (70) moves in the direction that closes the oil passage (98) with the needle valve (92).

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