Work vehicles

Abstract

To provide a work vehicle that can reliably electronically control an external hydraulic valve. [Solution] The system includes a work machine mounted on a vehicle body, an external hydraulic valve unit 60 that controls the hydraulic fluid that operates the valve spool 70 using a solenoid 64 and operates hydraulic equipment mounted on the work machine, and a pressure reducing valve 72 that controls the pressure of the hydraulic fluid that operates the valve spool 70. The pressure reducing valve 72 is installed between a branching point 74 where the hydraulic fluid that operates the valve spool 70 is branched from the pump 71 and 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 known a 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] Conventional external hydraulic operation levers and JOY stick levers are connected to an external hydraulic valve with wires and the like, and since the valve spool of the external hydraulic valve is directly operated, it could not be automatically operated depending on the surrounding environment or the state of the work vehicle.

[0005] Therefore, an object of the present invention is to provide a work vehicle capable of stably electronically controlling an external hydraulic valve.

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), an external hydraulic valve unit (60) that controls the hydraulic fluid that operates a valve spool (70) via a solenoid (64) and operates hydraulic equipment (17, 18) mounted on the work implement (14), and a pressure reducing valve (72) that controls the pressure of the hydraulic fluid that operates the valve spool (70). [Effects of the Invention]

[0008] According to the present invention, an external hydraulic valve can be electronically controlled in a stable manner. [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] Hydraulic circuit diagram of an external hydraulic valve for an agricultural tractor according to an embodiment of the present invention. [Figure 8] Developed diagram of the external hydraulic valve of an agricultural tractor according to an embodiment of the present invention. [Figure 9] Block diagram showing a control system 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 tractor 10's body, a main frame 16 pivotally connected to the upper part of the side frames 19 and supported to swing up and down, and a bucket 15 pivotally connected to the front end of the main frame 16 and supported to swing up and down. In addition, a main frame swinging cylinder 18 that can be extended and retracted is connected between the base of the side frames 19 and the central part of the main frame 16, and a bucket swinging cylinder 17 that controls the swinging 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] In addition, 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 of the machine body so as to be able to move up and down, and perform ground work.

[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 step surface 24 and a lower step surface 25. As shown in FIG. 4, the upper step surface 24 is formed at the rear outer side of the upper part of the right-side dashboard 22, and the lower step 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 concentrated and arranged on these upper step surface 24 and lower step surface 25.

[0021] On the upper step surface 24, a triple external hydraulic lever 34 is arranged.

[0022] At the front end of the lower step surface 25, a position lever 31 is arranged, and near the rear end of the position lever 31, a PTO changeover switch 32 and a tillage depth adjustment dial 33 are arranged. Further rearward of the PTO changeover switch 32 and the tillage depth adjustment dial 33, a PTO on / off switch 35 is arranged. The PTO changeover switch 32 is a switch for switching between an automatic mode in which the PTO is turned on and off in conjunction with the state of the vehicle and a manual mode in which it is performed 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 comes into contact with it. In addition, 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 easily accessible to the operator sitting in the driver's seat 21 with their right hand.

[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] An 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] As shown in Figure 7, the external hydraulic valve unit 60 is supplied with hydraulic fluid from the pump 71, and the pressure of the hydraulic fluid, which has been adjusted by the pressure reducing valve 72, is operated by a solenoid 64 to move the valve spool 70 and switch the destination of the hydraulic fluid supply. For example, this controls the extension and retraction of the main frame swinging cylinder 18 that swings the main frame 16 of the front loader 14. The tractor 10 also has an implement 80 attached to the rear, which is raised and lowered by a main cylinder 82 controlled by the main valve 81. The main valve 81 is supplied with hydraulic fluid from the pump 71, branching off from the branching point 74 through which the hydraulic fluid flows to the external hydraulic valve unit 60. Since the external hydraulic valve unit 60 is operated by hydraulic fluid whose pressure has been adjusted by the pressure reducing valve 72, even if the pressure in the oil passage including the branching point 74 becomes excessive due to the main valve 81, it can be operated stably by electronic control using the solenoid 64.

[0043] The oil supply from the upstream pump 71 branches at the branching point 74 into two oil passages: one that operates the valve spool 70, and another that supplies oil to the downstream main frame oscillating cylinder 18, main valve 81, and main cylinder 82, for example. Downstream of the branching point 74, a pressure compensation valve 73 is provided, which ensures that even if the rotational speed of the pump 71, which is operated by a prime mover such as an engine, drops due to idling, the supply oil passage to the pressure reducing valve 72, including the branching point 74, does not fall below the set pressure. As a result, the control pressure of the external hydraulic valve unit 60 can always be maintained at a constant pressure, allowing for stable electronic control.

[0044] The external hydraulic valve unit 60 has a stack configuration in which the body 69 is stacked with a first block 79 which comprises a branching point 74, and a second block 89 which comprises the main valve 81 and the oil passage to the tank 88. The pressure reducing valve 72 and the pressure compensating valve 73 are built into the first block 79. Since the first block 79 is necessary to supply hydraulic fluid from the pump 71 to the external hydraulic valve unit 60, space can be saved by integrating the pressure reducing valve 72 and the pressure compensating valve 73 into this first block 79.

[0045] As shown in Figure 8, a solenoid 64 is attached to the external hydraulic valve unit 60. The solenoid 64 is a push-pull solenoid, and by adjusting the current to push or pull, it switches which side of the piston 65 the hydraulic fluid is supplied to. By using a push-pull solenoid, it can be compactly configured with a single solenoid. The piston 65 is connected to the valve spool 70, and when it is pushed out, the hydraulic fluid flowing in from the first port 61 flows to the second port 62, the main frame oscillating cylinder 18 retracts, and the hydraulic fluid exiting the main frame oscillating cylinder 18 enters from the third port 63 and is discharged to the tank port 66. Conversely, when the valve spool 70 is retracted, the hydraulic fluid flowing in from the first port 61 flows to the third port 63, the main frame oscillating cylinder 18 extends, and the hydraulic fluid exiting the main frame oscillating cylinder 18 enters from the second port 62 and is discharged to the tank port 66.

[0046] As shown in Figure 9, the tractor 10 has a control unit 100 that controls the solenoid 64 based on signals input from sensors, etc. Specifically, signals from a JOY stick sensor 91 that detects the operation of the JOY stick lever 30, an external hydraulic lever sensor 92 that detects the operation of the external hydraulic lever 34, a steering sensor 93 that detects the steering angle of the wheels or the operation of the steering handle 20, a vehicle speed sensor 94 that detects the vehicle speed, a forward / reverse lever sensor 95 that detects the operation of the forward / reverse lever 45, a seat sensor 96 that detects whether the driver is seated or left the driver's seat 21, a clutch sensor 97 that detects the operation of the clutch pedal 47 or the clutch pressure, and a brake sensor 98 that detects the operation of the left and right brake pedals 48 or the operation of the brake device are input, and the solenoid 64 is electronically controlled to operate the external hydraulic valve unit 60.

[0047] With the above configuration, the tractor 10 can stably electronically control the valve spool 70 even if there are changes in the state of the main valve 81 or pump 71, thanks to the compact configuration of the external hydraulic valve unit 60.

[0048] 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 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]

[0049] 10. Tractor (vehicle body) 14. Front loader (work equipment) 17. Bucket swinging cylinder (hydraulic equipment) 18. Cylinder for main frame oscillation (hydraulic equipment) 60 External Hydraulic Valve Unit 64 Solenoid 70 Valve Spool 71 Pump 72 Pressure Reducing Valve 73 Pressure Compensation Valve 74 Branching Point 79 blocks

Claims

1. A work implement (14) attached to the vehicle body (10), An external hydraulic valve unit (60) controls the hydraulic fluid that operates the valve spool (70) using a solenoid (64) and operates the hydraulic equipment (17, 18) mounted on the work machine (14), A work vehicle equipped with a pressure reducing valve (72) that controls the pressure of the hydraulic fluid that operates the valve spool (70).

2. A pump (71) that supplies hydraulic fluid, A branching point (74) from the pump (71) to supply the hydraulic fluid that operates the valve spool (70), A pressure compensation valve (73) is provided downstream of the branching point (74) to compensate for the pressure in the oil passage including the branching point (74). The work vehicle according to claim 1, wherein the pressure reducing valve (72) is provided between the branching point (74) and the valve spool (70).

3. The work vehicle according to claim 2, wherein the branching point (74), the pressure reducing valve (72), and the pressure compensation valve (73) are configured inside a single block (79).

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