Work vehicle

Abstract

To arbitrarily change a shifting speed of a vehicle.SOLUTION: A work vehicle comprises a main transmission device which performs continuously variable transmission of a vehicle; a main transmission lever which, when the main transmission device is activated, is operated from a neutral position to either an acceleration side or a deceleration side; a main transmission lever sensor which detects a tilted angle of the main transmission lever; and a control section which outputs a transmission instruction value corresponding to the tilted angle of the main transmission lever detected by the main transmission lever sensor to the main transmission device. The control section is capable of storing the transmission instruction value corresponding to the tilted angle of the main transmission lever and performing constant-speed control to enable the vehicle to travel at a fixed travel speed corresponding to the stored transmission instruction value. The control section changes a shifting speed of the vehicle according to the tilted angle of the main transmission lever.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a work vehicle. [Background technology]

[0002] Conventionally, a technology has been known in which a work vehicle is equipped with a continuously variable transmission, and when a main shift lever is operated to continuously change the vehicle speed, the acceleration and deceleration during the vehicle speed change are controlled according to the operation speed and amount of the main shift lever (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-298050 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of agricultural work vehicles in which the engine speed is fixed and the vehicle speed is changed by main gear change during work, the degree of acceleration (speed increase) is determined by the gear change speed of the vehicle body, and this gear change speed cannot be changed arbitrarily in the above-mentioned conventional technology.

[0005] The present invention has been made in view of the above, and has an object to provide a work vehicle that can arbitrarily change the gear change speed of the vehicle body. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the work vehicle (1) according to the embodiment includes a main transmission (30) that continuously changes the speed of the vehicle body, and a neutral position (P N) to either the speed increasing side or the speed decreasing side, a main speed changing lever sensor (61) that detects the tilt angle of the main speed changing lever (15), and a control unit (100) that outputs a speed change command value corresponding to the tilt angle of the main speed changing lever (15) detected by the main speed changing lever sensor (61) to the main speed change device (30) to change the speed of the machine continuously. The control unit (100) stores the speed change command value corresponding to the tilt angle of the tilted main speed changing lever (15), and is capable of performing constant speed traveling control to travel the machine at a constant speed at the traveling speed of the stored speed change command value, and changes the speed change speed of the machine according to the tilt angle of the main speed changing lever (15). [Effects of the Invention]

[0007] According to the work vehicle of this embodiment, the gear change speed of the vehicle body can be changed as desired. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic side view showing a work vehicle according to an embodiment. [Figure 2] FIG. 2 is a diagram (part 1) showing the configuration of the transmission. [Figure 3] FIG. 3 is a diagram (part 2) showing the configuration of the transmission. [Figure 4] FIG. 4 is an explanatory diagram of the constant speed cruise control. [Figure 5] FIG. 5 is a diagram showing the operating positions of the main speed change lever. [Figure 6] FIG. 6 is a diagram showing the amount of operation of the main speed change lever. [Figure 7] FIG. 7 is a diagram showing the relationship between the operation amount and operation time of the main speed change lever and the degree of acceleration / deceleration. [Figure 8] FIG. 8 is a diagram showing the relationship between the amount of operation of the main speed change lever and the acceleration. [Figure 9] FIG. 9 is a diagram showing the first region of the main shift lever. [Figure 10] FIG. 10 is a diagram showing the second region of the main shift lever. [Figure 11] FIG. 11 is a perspective view (part 1) showing a lever biasing device. [Figure 12] FIG. 12 is a perspective view (part 2) showing the lever biasing device. [Figure 13] FIG. 13 is a perspective view (part 3) showing the lever biasing device. [Figure 14] FIG. 14 is an explanatory diagram of the biasing operation by the lever biasing device. [Figure 15] FIG. 15 is a schematic front view showing a lever biasing device according to a modified example. [Figure 16] FIG. 16 is a schematic side view of one side showing a lever biasing device according to a modified example. [Figure 17] FIG. 17 is a schematic side view of the other side showing the lever biasing device according to the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the work vehicle disclosed in the present application will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below.

[0010] <Overview of the work vehicle> An overview of a work vehicle 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic side view showing a work vehicle 1 according to an embodiment.

[0011] In addition, each figure may show a three-dimensional Cartesian coordinate system including a Z-axis whose positive direction is vertically upward (upward). For ease of explanation, the positive direction of the X-axis will be defined as the left, the negative direction of the X-axis as the right, the positive direction of the Y-axis as the forward direction, and the negative direction of the Y-axis as the backward direction, and the X-axis direction will be referred to as the left-right direction, the Y-axis direction as the front-back direction, and the Z-axis direction as the up-down direction.

[0012] In addition, the tractor 1, which is an example of a work vehicle, can travel on roads and fields using the power of a prime mover such as an engine E, which is the drive source, and can perform specified tasks in the field by detachably attaching multiple types of work implements (not shown) that each perform ground work.

[0013] In the following description, the work vehicle (tractor) 1 may be referred to as the "machine body."

[0014] As shown in Figure 1, the tractor 1 is equipped with an engine E mounted inside a hood 2 at the front of the vehicle body. Rotational power from the engine E is transmitted to a transmission 3, which is a transmission including a main transmission 30 (described later), and is then reduced in speed by the transmission 3 before being transmitted to the running wheels, i.e., the front wheels 4 and rear wheels 5 of the tractor 1.

[0015] A driver's seat 7 is provided in a cabin 6 at the rear of the aircraft. A steering wheel 8 for steering the front wheels 4 is provided in front of the driver's seat 7. A meter panel 9 and the like are provided in front of the steering wheel 8.

[0016] A work implement such as a rotary work implement is connected to the rear of the body of the tractor 1. The work implement is driven by a PTO (Power Take-Off) shaft 150 that protrudes rearward from a casing (transmission case) of the transmission 3.

[0017] In addition, around the driver's seat 7 within the cabin 6, in addition to a steering wheel 8 and a meter panel 9, various operating pedals such as an accelerator pedal 10, a clutch pedal 11, and a brake pedal 12, various operating levers such as a forward / reverse lever 14, a main shift lever 15, and an auxiliary shift lever (not shown), and various operating devices (not shown) are provided.

[0018] The forward / reverse lever 14 is an operating tool that is operated to operate a forward / reverse clutch 43 (see FIG. 3), which is a forward / reverse device that switches the vehicle between "forward," "neutral," and "reverse." The main speed change lever 15 is an operating tool that is operated to operate a main speed change device 30 that changes the vehicle's traveling speed (also called vehicle speed). The main speed change lever 15 is set in the neutral position P N (See Figure 5) to move to the speed increasing or decreasing side.

[0019] The tractor 1 can perform automatic gear shifting by controlling the transmission 3 according to the rotation speed of the engine E. Furthermore, as will be described later, the tractor 1 can also switch the main gear simply by operating the accelerator pedal 10 or the main gear shift lever 15.

[0020] <Transmission configuration> The power transmission configuration of the work vehicle 1 according to this embodiment will be described with reference to Figures 2 and 3. Figures 2 and 3 are diagrams (power transmission diagrams) showing the configuration of the transmission 3.

[0021] The tractor 1 is equipped with a hydrostatic continuously variable transmission (hereinafter referred to as HST (Hydro Static Transmission)) 31 equipped with a hydraulic pump 311 and a hydraulic motor 312, and a hydromechanical continuously variable transmission (hereinafter referred to as HMT (Hydro Mechanical Transmission)) 30 combined with a planetary gear (planetary gear mechanism 33).

[0022] The main transmission, HMT30, combines the HST31 and planetary gear mechanism 33, making it possible to start, accelerate (increase speed), and decelerate the machine with only lever or pedal operation, and also enables the machine to travel with higher transmission efficiency than a transmission configuration with only the HST31. Furthermore, when combined with electronic control, the HMT30 enables constant speed traveling, which allows the machine to travel at a constant speed (constant speed).

[0023] 2 and 3, in the transmission 3, the HST 31 includes a variable displacement hydraulic pump 311 and a fixed displacement hydraulic motor 312. The hydraulic pump 311 and the hydraulic motor 312 are housed in a housing (not shown) of the HST 31. A pump output shaft 32 is inserted into the hydraulic pump 311 along the rotation axis of the hydraulic pump 311. The pump output shaft 32 transmits power from the engine E to the hydraulic pump 311, the planetary gear mechanism 33, and the PTO shaft 150.

[0024] The transmission 3 is housed in a transmission case (not shown). In addition to the pump output shaft 32, the transmission 3 is provided with a motor output shaft 34, an output shaft 35, a sub-transmission shaft 37a, a PTO shaft 150, and other components that are rotatable. The transmission 3 is also provided with a planetary gear mechanism 33. The planetary gear mechanism 33 is disposed behind the HST 31 (downstream in the transmission direction). The planetary gear mechanism 33 includes a sun gear 331, a planetary gear 332, a ring gear 333, and a carrier 334.

[0025] A hydraulic clutch 36 is provided on the rear side (downstream side in the transmission direction) of the planetary gear mechanism 33. The hydraulic clutch 36 includes a front clutch 361 and a rear clutch 362. The hydraulic clutch 36 switches between HST mode and HMT mode. The hydraulic clutch 36 transmits power to the output shaft 35 in accordance with the two modes (HST mode and HMT mode), and transmits the power to the sub-transmission shaft 37a via the sub-transmission mechanism 37.

[0026] A pump-side input gear 38 is provided on the pump output shaft 32. The pump-side input gear 38 meshes with a gear 334a of a carrier 334 that is loosely fitted concentrically with the sun gear 331, thereby driving the carrier 334 to rotate. The carrier 334 is provided with a plurality of planet gears 332 that mesh with the sun gear 331 and the ring gear 333. In this way, the planetary gear mechanism 33 is made up of the sun gear 331, the plurality of planet gears 332, the ring gear 333, the carrier 334, etc.

[0027] In the planetary gear mechanism 33, the sun gear 331 is loosely fitted to the output shaft 35, and the planetary gear 332 meshes with the sun gear 331 and the ring gear 333. The planetary gear 332 is rotatably supported by a carrier 334 that is loosely fitted to the output shaft 35, and is configured to revolve around the sun gear 331 while rotating on its own axis.

[0028] A motor-side input gear 39 is provided on the motor output shaft 34. The motor-side input gear 39 drives the sun gear 331 to rotate.

[0029] The auxiliary transmission mechanism 37 transmits power to an auxiliary transmission shaft 37a when the auxiliary transmission clutch is engaged. The auxiliary transmission shaft 37a is configured to be able to transmit power to a rear wheel differential 40 via a pinion provided on the auxiliary transmission shaft 37a. The auxiliary transmission shaft 37a is also configured to be able to drive the front wheels 4 via a front wheel speed increase switching mechanism 41 and a front wheel differential 42.

[0030] Here, the transmission configurations in the HST mode and the HMT mode will be described. As shown in Figure 3, in the HMT mode, the front clutch 361 of the hydraulic clutch 36 is engaged and the rear clutch 362 is disengaged.

[0031] At this time, the sun gear 331 of the planetary gear mechanism 33 is rotationally driven by the rotational power of the pump output shaft 32. Due to the rotation of the sun gear 331, the rotation of the carrier 334 and the sun gear 331 is combined and transmitted to the planetary gear 332. The power transmitted to the sun gear 331 is transmitted to the ring gear 333.

[0032] In the HMT mode, the front clutch 361 of the hydraulic clutch 36 is controlled to be connected, and the rotational power of the ring gear 333 is transmitted to the output shaft 35. The power of the output shaft 35 is transmitted to the rear wheels 5 and the front wheels 4 via the auxiliary transmission mechanism 37.

[0033] On the other hand, in the HST mode, the rear clutch 362 of the hydraulic clutch 36 is engaged and the front clutch 361 is disengaged. In the HST mode, the rotational power of the motor output shaft 34 is transmitted to the output shaft 35. The power of the output shaft 35 is transmitted to the rear wheels 5 and the front wheels 4 via the auxiliary transmission mechanism 37.

[0034] In the HST mode, the rotational power of the engine E is transmitted to the rear wheels 5 and the front wheels 4 without passing through the planetary gear mechanism 33. That is, the power of the engine E rotates the carrier 334 via the pump output shaft 32, but since the carrier 334 simply rotates idle, the power is changed in speed by the HST 31 and transmitted from the motor output shaft 34 to the output shaft 35, and then transmitted to the rear wheels 5 and the front wheels 4 via the sub-transmission mechanism 37.

[0035] As shown in Fig. 3, the tractor 1 (see Fig. 1) includes a control unit 100. When the main speed change lever 15 is operated, the control unit 100 outputs a speed change command value corresponding to the operation position P (see Fig. 5) of the main speed change lever 15 to the HMT 30, which is the main transmission. In this way, the HMT 30 is controlled by the control unit 100.

[0036] The control unit 100 is a computer equipped with a processing device such as a CPU (Central Processing Unit), a storage device such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disk Drive), and further an input / output device.

[0037] The control unit 100 includes a driving system ECU (Electronic Control Unit) that controls the driving system, an engine ECU as an engine control unit that controls the engine E, and a work implement lifting system ECU that controls the lifting and lowering of a work implement such as a rotary tiller.

[0038] Connected to the control unit 100 are an electronic governor (actuator) 51 that controls the rotation speed of the engine E, a sensor 52 that detects the rotation speed of the engine E (output shaft of the engine E), and a main shift lever sensor 61 that detects the operating position (also referred to as the shift position) P (see FIG. 5) of the main shift lever 15. Note that the main shift lever sensor 61 can be, for example, a potentiometer that detects the rotation (tilting) angle of the main shift lever 15. Therefore, the main shift lever sensor 60 can detect the tilt angle of the main shift lever 15.

[0039] In addition, the control unit 100 is connected to a forward / reverse lever sensor 71 that detects the operating position of the forward / reverse lever 14, a sensor 53 that detects the rotational speed of the motor output shaft 34, a speed change actuator 54 that controls the swash plate of the hydraulic pump 311, and solenoid valves 55, 56 that connect / disconnect the hydraulic clutch 36.

[0040] In this way, by electrically connecting sensors 52, 53, etc., the control unit 100 feedback controls the inclination angle of the movable swash plate of the hydraulic pump 311 via the shift actuator 54 based on the operating position P of the main shift lever 15 and the detection values ​​of sensors 52, 53 so that the traveling speed (vehicle speed) of the tractor 1 becomes the shift command value corresponding to the operating position P of the main shift lever 15.

[0041] In the gear shift control of the control unit 100, for example, the HMT mode is executed in the medium to high speed range, and the HST mode is executed in the low speed range, and two driving modes are automatically switched in accordance with the gear shift command value.

[0042] The forward / reverse lever 14 is operated to operate a forward / reverse clutch 43, which is a forward / reverse device. The forward / reverse clutch 43 switches the vehicle between "forward", "reverse" and "neutral". The control unit 100 can control the forward / reverse clutch 43.

[0043] When the forward / reverse lever sensor 71 detects that the operational position of the forward / reverse lever 14 is "forward," the control unit 100 controls the speed change actuator so that the movable swash plate of the hydraulic pump 311 is within the range of the forward position. When the control unit 100 detects that the operational position of the forward / reverse lever 14 is "reverse," the control unit 100 controls the speed change actuator so that the movable swash plate of the hydraulic pump 311 is within the range of the reverse position.

[0044] Furthermore, when the control unit 100 detects that the operating position of the forward / reverse lever 14 is "neutral," it controls the speed change actuator to hold the movable swash plate of the hydraulic pump 311 in the neutral position, thereby preventing rotation of the output shaft 35. Note that the forward / reverse lever sensor 71 may be, for example, a potentiometer that detects the rotation angle of the forward / reverse lever 14, or a switch having contacts that correspond to the respective positions of "forward," "reverse," and "neutral."

[0045] 3, a gear shift memory switch 62 that is operated to store the operating position P of the main shift lever 15 is connected to the control unit 100. The gear shift memory switch 62 is operated by the driver of the tractor 1 or the like when storing the operating position P of the main shift lever 15 detected by the main shift lever sensor 61.

[0046] As described above, the control unit 100 outputs to the HMT 30 a gear shift command value corresponding to the operating position P of the main shift lever 15. When the main shift lever 15 is operated, the control unit 100 changes the gear shift command value output to the HMT 30 in accordance with the operating position P of the main shift lever 15.

[0047] Here, the tractor 1 (see FIG. 1) is capable of constant speed traveling at a vehicle speed specified by the driver. For this reason, the control unit 100 performs constant speed traveling control to make the tractor 1 travel at a constant speed. By the control unit 100 performing constant speed traveling control, the tractor 1 travels at a constant speed specified by the main shift lever 15 and stored by the control unit 100. This constant speed traveling control is also called memory speed change control.

[0048] <Constant speed cruise control (part 1)> The constant speed traveling control will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram of the constant speed traveling control, and is a flowchart showing a general processing procedure performed by the control unit 100 during the constant speed traveling control.

[0049] When constant speed cruise control is performed, the control unit 100 (see FIG. 3) acquires the operation position P (see FIG. 5) when the driver tilts the main shift lever 15 (see FIG. 3), and stores a gear change command value corresponding to the operation position P of the main shift lever 15 (step S101). The control unit 100 may store the operation position P of the main shift lever 15. The control unit 100 acquires the operation position P of the main shift lever 15 from the detection value of the main shift lever sensor 61 (see FIG. 3).

[0050] The control unit 100 outputs the gear change instruction value stored in the processing of step S101 to the HMT 30 (see Figure 2), and starts constant speed traveling of the vehicle at the speed (vehicle speed) of the gear change instruction value corresponding to the operating position P of the main gear change lever 15 (step S102).

[0051] Thereafter, the control unit 100 terminates the constant speed traveling control (step S104) in response to an operation by the driver to terminate the constant speed traveling (step S103). The operation to terminate the constant speed traveling control may be, for example, an operation of a separately provided constant speed traveling cancel switch.

[0052] <Main gear shift lever (part 1)> The main speed change lever 15 will be described with reference to Figures 5 to 7. Figure 5 is a diagram showing the operation position P of the main speed change lever 15. Figure 6 is a diagram showing the operation amount of the main speed change lever 15. Figure 7 is a diagram showing the relationship between the operation amount and operation time of the main speed change lever 15 and the degree of acceleration / deceleration.

[0053] The main shift lever 15 is an operating tool (operating lever) operated by the driver, and is located on either the left or right side of the driver's seat 7 (see FIG. 1). The main shift lever 15 is provided so that it can be tilted forward or backward. The main shift lever 15 may be provided, for example, on an armrest around the driver's seat 7. The main shift lever 15 may also be provided, for example, on a lever guide.

[0054] As shown in FIG. 5, the main speed change lever 15 is in the neutral position P N When the aircraft is tilted forward from the neutral position P NWhen the main speed change lever 15 is tilted backward from the neutral position P N When the aircraft is tilted forward from the neutral position P N When the vehicle is tilted backward from the neutral position P, the vehicle slows down, allowing the driver to operate the vehicle in a way that suits his or her senses. N The further away from the aircraft is towards the front or rear, the greater the speed increase or decrease.

[0055] The main speed change lever 15 is in the neutral position P N The maximum speed-up position P (maximum speed-up position P H ) and the neutral position P N From the rear of the aircraft, the maximum deceleration operation position P (maximum deceleration position P L ) and can be tilted up to.

[0056] After the main shift lever 15 is operated, if the driver releases his / her hand from the main shift lever 15 or releases the force applied to the main shift lever 15, the main shift lever 15 returns to the neutral position P N To return to the neutral position P N The main speed change lever 15 is biased toward the neutral position P by a predetermined biasing force F of a biasing member such as a spring. N The pressure is biased to the side.

[0057] The main speed change lever 15 has a neutral position P N A predetermined dead zone A is set on the front side (i.e., the speed increasing side) and rear side (i.e., the speed decreasing side) of the main shift lever 15. By setting the dead zone A in the main shift lever 15 in this way, the driver can perform an operation that suits his or her senses.

[0058] In addition, in the tractor 1 (see FIG. 1), when the main speed change lever 15 is operated forward (to increase speed) or backward (to decrease speed), for example, the speed increase or deceleration of the tractor 1 changes at a constant rate. For example, the speed increase or deceleration of the tractor 1 changes proportionally (linearly). When the main speed change lever 15 is in the neutral position P NWhen the main speed change lever 15 is tilted from the neutral position P to the speed-up side, the aircraft speed increases according to the amount of operation (in this case, the tilt angle), and the main speed change lever 15 returns to the neutral position P N When tilted from the left to the right to decelerate, the aircraft will decelerate according to the amount of tilt (tilt angle).

[0059] That is, in the tractor 1, by holding the main speed change lever 15 forward (to the speed increase side) for a certain period of time or more, the speed of the machine can be increased to the maximum speed. Also, in the tractor 1, by holding the main speed change lever 15 backward (to the speed decrease side) for a certain period of time or more, the speed of the machine can be increased to the minimum speed. The minimum speed of the machine is, for example, creep speed. Note that the minimum speed of the machine may also be, for example, a stop (zero speed).

[0060] The main speed change lever 15 is divided into a plurality of operation areas, each of which has a forward speed increase side and a rearward speed decrease side, and has a neutral position P N The main speed change lever 15 is set so that the acceleration or deceleration rate increases as the range becomes farther from the neutral position P N The first stage area is closer to the neutral position P N The operation area is divided into two, the first area being the area farther from the first area, and the second area being the area farther from the first area, and the acceleration or deceleration rate is set to be greater in the second area than in the first area.

[0061] The main speed change lever 15 is biased so that the biasing force F increases stepwise on both the speed increase side and the speed decrease side. In this case, the main speed change lever 15 is in the neutral position P N The main speed change lever 15 is biased by a first-stage biasing force from a predetermined operating amount to a predetermined operating amount, and when the operating amount increases beyond this operating amount, the main speed change lever 15 is biased by a second-stage biasing force greater than the first stage. In this way, the main speed change lever 15 is biased so that the biasing force F increases in two stages on both the speed-up side and the speed-down side. The biasing structure of the main speed change lever 15 will be described later using Figures 11 to 16.

[0062] As shown in FIGS. 6 and 7, for example, when the main speed change lever 15 is in the neutral position P NWhen the main shift lever 15 is tilted 50% from the neutral position P to the forward side (speed increasing side), the vehicle speed increases to the maximum speed increasing value ("10" in the case of main shift stages "1" to "10") in 5 seconds. N When the vehicle is tilted 100% (maximum operation) from the left to the front (accelerating side), the vehicle speed increases to the maximum acceleration value ("10" in the case of main gear stages "1" to "10") in 1 second, for example.

[0063] In the case of deceleration, as in the case of speeding up, the main speed change lever 15 is in the neutral position P N When the main shift lever 15 is tilted 50% from the neutral position P to the rear (deceleration side), the vehicle speed is decelerated to the maximum deceleration value ("-10" in the case of main shift stages "-1" to "-10") in 5 seconds, for example. N When the vehicle is tilted 100% (maximum operation) from the left to the right (deceleration side), the vehicle speed is decelerated to the maximum deceleration value ("-10" in the case of main gear stages "-1" to "-10") in 1 second, for example.

[0064] <Constant speed cruise control (part 2)> The constant speed cruise control will be further explained. The control unit 100 changes the speed change command value output to the HMT 30 (see FIG. 3) according to the operation position P of the main speed change lever 15, and when the driver of the tractor 1 determines that the desired vehicle speed has been reached and releases his / her hand from the main speed change lever 15, the main speed change lever 15 is returned to the neutral position P. N , the main speed change lever 15 returns to the neutral position P N That is, the control unit 100 holds the gear shift command value corresponding to the operation position P before the main gear shift lever 15 returns to the neutral position P. N Tractor 1 is driven at a constant speed at the speed just before returning to (immediately before).

[0065] When performing constant speed traveling control, the control unit 100 stores a shift command value corresponding to the operating position P of the main shift lever 15 tilted by the driver of the tractor 1, and outputs the stored shift command value to the HMT 30 (see Figure 2) to start constant speed traveling of the vehicle at the speed (vehicle speed) of the operating position P of the main shift lever 15.

[0066] As described above, the tractor 1 is in the neutral position P N Therefore, when the driver releases the main shift lever 15, the main shift lever 15P N is the neutral position P N At this time, the gear shift command value is maintained. When the main gear shift lever 15 is in the neutral position P N Since the gear change command value is maintained even when the vehicle returns to , the driver feels as if he or she is operating the vehicle to increase or decrease speed during constant speed travel control. This reduces driver confusion caused by a discrepancy between the actual vehicle speed during constant speed travel and the operating position of the main gear change lever 15.

[0067] In addition, constant speed travel can be started by operating the main speed change lever 15 with the feeling of operating to increase the speed of the vehicle, which reduces confusion among the driver due to a discrepancy between the actual vehicle speed and the operating position P of the main speed change lever 15.

[0068] <Main gear shift lever (part 2)> The main shift lever 15 will be further described with reference to Figures 8 to 11. Figure 8 is a diagram showing the relationship between the operation amount (tilt amount, i.e., tilt angle) of the main shift lever 15 and the acceleration (speed increase) and deceleration. Figure 9 is a diagram showing a first area A1 of the main shift lever 15. Figure 10 is a diagram showing a second area A2 of the main shift lever 15.

[0069] As shown in FIG. 8, the main speed change lever 15 has a first area A1 ("-a to 0" in the figure) where the operating load is light, on both the front side (speed increase side) and the rear side (speed decrease side) of the main speed change lever 15. N ) to a"), and a second area A2 ("-a to -b, a to b" in the figure) where the operating load is heavier than in the first area. In the first area A1, the main speed change lever 15 provides a gradual (small) change in acceleration (or deceleration) so that the tractor 1 can easily go from an extremely slow speed to a slow speed.

[0070] Furthermore, in the main speed change lever 15, the acceleration (or deceleration) changes suddenly (largely) in the second region A2 so that the tractor 1 can quickly reach the set vehicle speed.

[0071] In this way, the control unit 100 (see FIG. 3) changes the speed change speed of the tractor 1 according to the tilt angle of the main speed change lever 15. With this configuration, it is possible to control the speed change speed of the machine, that is, the acceleration (speed increase) rate of the machine, by tilting the main speed change lever 15. This makes it possible to arbitrarily change the speed change speed of the machine.

[0072] 9, the control unit 100 determines whether the main speed change lever 15 is in the neutral position P N From the first area A1, the operation load is light, and then the neutral position P N When the operation is performed to return the gear to the position, a vehicle equipped with a continuously variable transmission (main transmission 30) such as the tractor 1 can achieve a pseudo-step-variable speed change.

[0073] 10, the control unit 100 determines whether the main speed change lever 15 is in the neutral position P N From the second area A2, the operation load is heavy, and then the neutral position P N Even when the shift lever is operated to return to the original position, a shift similar to a stepped shift can be realized in a vehicle equipped with a continuously variable transmission (main transmission 30).

[0074] Furthermore, when the tractor 1 starts moving, even if the main shift lever 15 is tilted beyond a predetermined angle, the control unit 100 does not change the shift speed of the tractor 1. This configuration makes it possible to prevent the machine from suddenly starting moving, thereby improving safety.

[0075] As described above, the main shift lever 15 is biased so that the biasing force F increases stepwise on both the speed-up side and the speed-down side. Therefore, when the main shift lever 15 is tilted, the control unit 100 changes the vehicle's speed change speed stepwise based on a predetermined angle. With this configuration, the vehicle's speed change speed changes stepwise with changes in the operating load of the main shift lever 15 as a boundary, allowing the driver to intuitively control the acceleration (speed increase) rate.

[0076] The tractor 1 further includes a lever biasing device 80 for biasing the main speed change lever 15 in stages.

[0077] <Lever biasing device> The lever biasing device 80 will be described with reference to Figures 11 to 13. Figures 11 to 13 are perspective views showing the lever biasing device 80. Figure 14 is an explanatory diagram of the biasing operation by the lever biasing device 80. The lever biasing device 80 is configured to bias the main speed change lever 15 to either the speed increase side or the speed decrease side, and then to bias the main speed change lever 15 to the neutral position P N (See FIG. 8) to bias the main shift lever 15 back to the original position.

[0078] As shown in Figures 11 to 13, the lever biasing device 80 is provided on the base end side, which is the rotation end of the main shift lever 15. The lever biasing device 80 includes a base 81, a first biasing member 821, and a second biasing member 822. The base 81 is attached to the base end of the main shift lever 15. The base 81 supports the main shift lever 15 so that it can rotate in one direction (the front-to-rear direction indicated by arrows Y1 and Y2 in the figures). This allows the main shift lever 15 to tilt in the front-to-rear direction.

[0079] The base 81 includes two plate-shaped case members 811, a spacer member 812, and a groove 813. The two case members 811 are provided facing each other with a predetermined gap between them. The spacer member 812 is provided between the two case members 811. The spacer member 812 is located between the two case members 811, thereby forming a space between the two case members 811.

[0080] The groove 813 is formed on the upper surface of the base 81. The groove 813 is a gap between the two case members 811. The main shift lever 15 is rotatably supported on the base 81 by attaching a first shaft 151 provided at the base end of the main shift lever 15 to the two case members 811. The main shift lever 15 is disposed between the two case members 811. The main shift lever 15 is disposed inside the groove 813. The main shift lever 15 moves back and forth inside the groove 813 in response to tilting of the main shift lever 15.

[0081] A window portion 814 is formed in each of the two case members 811. Two second shaft portions 152 provided at the base end portion of the main shift lever 15 are inserted into the window portions 814. The two second shaft portions 152 extend in the left-right direction perpendicular to the front-to-rear direction, and are provided in front of and behind the base end portion 15a of the main shift lever 15, with the base end portion sandwiched between them. The two second shaft portions 152 move inside the window portion 814 in response to the tilt of the main shift lever 15 in the front-to-rear direction.

[0082] A first spring (torsion spring) 821, which is a first biasing member, is arranged on one (case member 811a) side of the two case members 811. The first spring 821 includes a coil portion 821a and two arm portions 821b. The coil portion 821a is attached to the first shaft portion 151 of the main shift lever 15. The two arm portions 821b are inserted into openings 815 formed in the upper surface of one case member 811a.

[0083] Such a first spring 821 keeps the main shift lever 15 in the neutral position P N The force is applied in the direction of returning to the position.

[0084] A second spring (torsion spring) 822, which is a second biasing member, is arranged on the other (case member 811b) side of the two case members 811. The second spring 822 includes a coil portion 822a and two arm portions 822b. The coil portion 822a is attached to the first shaft portion 151 of the main shift lever 15. The two arm portions 822b are inserted into openings 815 formed in the upper surface of the other case member 811b. The opening 815 through which the arm portion 822b is inserted is shorter in the front-rear direction than the opening 815 through which the arm portion 821b of the first spring 821 is inserted.

[0085] When the tilt angle of the tilted main speed change lever 15 reaches or exceeds a predetermined angle, the second spring 822 causes the main speed change lever 15 to move to the neutral position P N The force is applied in the direction of returning to the position.

[0086] As shown in FIG. 14, the lever biasing device 80 is configured to bias the main speed change lever 15 to the neutral position P N For example, when the steering wheel is tilted to the acceleration side, the first stage (0) (neutral position P N When the main shift lever 15 is tilted further from the first stage toward the speed-up side, the lever biasing device 80 is biased by a biasing force F (F2) of the first spring 821 (arm portion 821b) and the second spring 822 (arm portion 822b) in the second stage (from "-a to -b").

[0087] In this way, the main speed change lever 15 is biased so that the biasing force F increases in two stages on the speed increasing side (speed decreasing side).

[0088] According to this configuration, the first spring 821 keeps the main shift lever 15 in the neutral position P N In addition to being biased to return to the neutral position P when the main speed change lever 15 is tilted beyond a predetermined angle, the second spring 822 also biases the main speed change lever 15 back to the neutral position P N Therefore, the more the driver tilts the main shift lever 15, the greater the operating load at the hand. This allows the driver to get a step-by-step operating feel.

[0089] <Modifications of the lever biasing device> A modified example of the lever biasing device 80 (lever biasing device 80A) will be described with reference to Figures 15 to 17. Figure 15 is a schematic front view showing the lever biasing device 80A according to the modified example. Figure 16 is a schematic side view of one side showing the lever biasing device 80A according to the modified example. Figure 17 is a schematic side view of the other side showing the lever biasing device 80A according to the modified example.

[0090] As shown in Figures 15 to 17, a lever biasing device 80A according to a modified example is provided on the base end side, which is the rotation end of the main shift lever 15. The lever biasing device 80A includes a base 81, a first biasing member 821, and a second biasing member 822. The base 81 is attached to the base end of the main shift lever 15. The base 81 supports the main shift lever 15 so that it can rotate in one direction (the front-to-rear direction indicated by arrows Y1 and Y2 in Figures 16 and 17). This allows the main shift lever 15 to tilt in the front-to-rear direction.

[0091] The base 81 supports the main shift lever 15 so that it can rotate in the front-to-rear direction. In other words, the main shift lever 15 is supported so that it can rotate around a first shaft 151, which serves as a rotation fulcrum. The main shift lever 15 has a second shaft 152 located closer to the base end than the first shaft 151. When the main shift lever 15 is tilted, the second shaft 152 rotates in the direction opposite to the tilting direction of the main shift lever 15.

[0092] First spring 821, which is a first biasing member, is disposed on one surface of base 81. First spring 821 includes a coil portion 821a and two arm portions 821b. Coil portion 821a is attached to, for example, fixed portion 816 provided on base 81. Note that fixed portion 816 may not be provided on base 81 but may be provided on a member separate from base 81, or coil portion 821a may be fixed to a member separate from base 81.

[0093] The two arm portions 821b each extend upward from the coil portion 821a toward the second shaft portion 152 of the main shift lever 15. The second shaft portion 152 of the main shift lever is disposed between the two arm portions 821b.

[0094] Such a first spring 821 keeps the main shift lever 15 in the neutral position P N The force is applied in the direction of returning to the position.

[0095] A second spring 822, which is a second biasing member, is disposed on the other surface of the base 81. The second spring 822 includes a coil portion 822a and two arm portions 822b. The coil portion 822a is attached to a fixed portion 816 provided on the base 81, for example. Note that the fixed portion 816 may not be provided on the base 81 but may be provided on a member separate from the base 81, or the coil portion 822a may be fixed to a member separate from the base 81.

[0096] The two arm portions 822b each extend upward from the coil portion 822a toward the second shaft portion 152 of the main shift lever 15. The second shaft portion 152 of the main shift lever is disposed between the two arm portions 822b. The distance between the two arm portions 822b of the second spring 822 is greater than the distance between the two arm portions 821b of the first spring 821.

[0097] When the tilt angle of the tilted main speed change lever 15 reaches or exceeds a predetermined angle, the second spring 822 causes the main speed change lever 15 to move to the neutral position P N The force is applied in the direction of returning to the position.

[0098] When the main speed change lever 15 is tilted from the neutral position in an upright posture to, for example, the speed increasing side, the lever biasing device 80A is biased to the first stage ("0" shown in FIG. 8) N When main shift lever 15 is tilted further from the first stage toward the speed-up side, lever biasing device 80A is biased by the biasing forces of first spring 821 (arm portion 821b) and second spring 822 (arm portion 822b) at the second stage ("-a to -b" shown in FIG. 8).

[0099] In this way, the main speed change lever 15 is biased so that the biasing force F increases in two stages on the speed increasing side (speed decreasing side).

[0100] According to this configuration, the first spring 821 keeps the main shift lever 15 in the neutral position P N In addition to being biased to return to the neutral position P when the main speed change lever 15 is tilted beyond a predetermined angle, the second spring 822 also biases the main speed change lever 15 back to the neutral position P N Therefore, the more the driver tilts the main shift lever 15, the greater the operating load at the hand. This allows the driver to get a step-by-step operating feel.

[0101] The above-described embodiment realizes the following work vehicle 1.

[0102] (1) A main transmission 30 that continuously changes the speed of the aircraft, and a neutral position P N a main speed change lever sensor 61 that detects the tilt angle of the main speed change lever 15; and a control unit 100 that outputs a speed change command value corresponding to the tilt angle of the main speed change lever 15 detected by the main speed change lever sensor 61 to the main transmission 30, thereby causing the vehicle to change speed continuously. The control unit 100 stores the speed change command value corresponding to the tilt angle of the tilted main speed change lever 15, and is capable of performing constant speed traveling control that causes the vehicle to travel at a constant speed at the traveling speed of the stored speed change command value, and changes the vehicle's speed change speed according to the tilt angle of the main speed change lever 15.

[0103] With this type of work vehicle 1, it is possible to operate the vehicle's speed change speed, i.e., the vehicle's acceleration (speed increase) rate, by tilting the main speed change lever 15. This allows the vehicle's speed change speed to be changed as desired.

[0104] (2) In the above (1), after the main shift lever 15 is tilted, the tilted main shift lever 15 is returned to the neutral position P NThe lever biasing device 80 biases the main shift lever 15 to return to the neutral position P N When the tilt angle of the tilted main speed change lever 15 reaches or exceeds a predetermined angle, the main speed change lever 15 is returned to the neutral position P N and a second biasing member 822 that biases the main speed change lever 15 in the direction returning it to the original position.

[0105] In addition to the effect (1) above, the work vehicle 1 has the advantage that the first biasing member 821 prevents the main shift lever 15 from being in the neutral position P N In addition to being biased to return to the neutral position P when the main shift lever 15 is tilted by a predetermined angle or more, the second biasing member 822 also biases the main shift lever 15 to the neutral position P N Therefore, the more the driver tilts the main shift lever 15, the greater the operating load at the hand. This allows the driver to get a step-by-step operating feel.

[0106] (3) In the work vehicle 1 described above in (2), the control unit 100 does not change the vehicle's gear change speed when the vehicle starts moving, even if the main shift lever 15 is tilted beyond a predetermined angle.

[0107] In addition to the effect of (2) above, such a work vehicle 1 can also suppress sudden acceleration of the vehicle, thereby improving safety.

[0108] (4) In the work vehicle 1 described above in (3), when the main shift lever 15 is tilted, the control unit 100 changes the gear change speed of the vehicle in stages based on a predetermined angle.

[0109] In addition to the effect of (3) above, with such a work vehicle 1, the shift speed of the vehicle changes stepwise depending on the change in the operating load of the main shift lever 15, allowing the driver to intuitively control the acceleration (speed increase) rate.

[0110] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0111] 1. Work vehicle (tractor) 15 Main gear shift lever 30 Main Transmission (HMT) 61 Main shift lever sensor 80 Lever actuating device 100 control section 821 First biasing member (first spring) 822 Second biasing member (second spring) P N neutral position

Claims

1. A main transmission that continuously changes the speed of the aircraft; a main speed change lever that is tilted from a neutral position to either an accelerating side or a decelerating side when operating the main speed change device; a main speed change lever sensor that detects the tilt angle of the main speed change lever; a control unit that outputs a speed change command value corresponding to the tilt angle of the main speed change lever detected by the main speed change lever sensor to the main speed change device, thereby continuously changing the speed of the aircraft; Equipped with The control unit A speed change command value corresponding to the tilt angle of the tilted main speed change lever is stored, and constant speed travel control is performed to travel the vehicle at a constant speed at the travel speed of the stored speed change command value, A work vehicle in which the gear shift speed of the vehicle body is changed according to the tilt angle of the main shift lever.

2. a lever biasing device that biases the main shift lever so that the tilted main shift lever returns to a neutral position after the main shift lever is tilted; Equipped with The lever biasing device a first biasing member that biases the main shift lever in a direction returning it to the neutral position; 2. The work vehicle according to claim 1, further comprising a second biasing member that biases the main shift lever in a direction returning it to the neutral position when the tilt angle of the tilted main shift lever reaches a predetermined angle or greater.

3. The control unit 3. The work vehicle according to claim 2, wherein when the vehicle starts moving, the vehicle's shift speed does not change even if the main shift lever is tilted beyond the predetermined angle.

4. The control unit The work vehicle according to claim 3, wherein when the main shift lever is tilted, the shift speed of the vehicle is changed in stages based on the predetermined angle.

Images