Work vehicle

Abstract

To provide a work vehicle which suppresses an engine starting due to short circuit of a signal line, in a speed change gear state which is not suitable for engine start.SOLUTION: A work vehicle includes: a speed change operation tool 72 for operating a speed change position of a speed change gear T2; an engine control unit 4 for starting an engine E based on a start command from a start operation tool 73 and an operation state of the speed change operation tool 72; a neutral position detector 81 for detecting a neutral position of the speed change operation tool 72 and outputting a neutral position signal; an operation displacement amount detector 82 for detecting an operation displacement amount of the speed change operation tool 72, and for outputting an operation displacement amount signal; a first safety determination part 41 for responding to the neutral position signal and for determining a first safety state; and a second safety determination part 42 for determining a second safety state based on the operation displacement amount. When the engine control unit 4 receives a start command in a state where the first safety state and the second safety state are determined, it starts the engine E.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a work vehicle equipped with an engine, a start operating device that outputs a start command, a shift operating device that operates the shift position of a transmission, and an engine control unit that starts the engine based on the start command and the operating state of the shift operating device. [Background technology]

[0002] In the work vehicle disclosed in Patent Document 1, the PTO clutch lever can be pivoted about a pivot axis extending in the left-right direction of the vehicle body, and can be selected between an ON position where the PTO clutch is in a transmitted state and an OFF position where the PTO clutch is in a disengaged state. A safety switch is provided to detect when the PTO clutch lever is in the OFF position, and the work vehicle is configured so that the engine cannot be started when the PTO clutch lever is in the ON position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-034680 A (see paragraph 0034, Figures 7 and 8) Summary of the Invention [Problem to be solved by the invention]

[0004] Even in work vehicles that are not equipped with a PTO (power take-off) device, the engine may start in an unsuitable transmission state. Compared to passenger cars, work vehicles are driven in harsher environments, making them more susceptible to malfunctions such as short circuits in signal lines. In such cases, the engine may start in an unsuitable transmission state.

[0005] An object of the present invention is to provide a work vehicle that prevents the engine from starting due to a short circuit in a signal line or the like when the transmission is in a state that is not suitable for starting the engine. [Means for solving the problem]

[0006] A work vehicle according to the present invention comprises an engine, a start operating device that outputs a start command, a speed change operating device that operates the speed position of a transmission, an engine control unit that starts the engine based on the start command and the operating state of the speed change operating device, a neutral position detector that detects the neutral position of the speed change operating device and outputs a neutral position signal, and an operation displacement amount detector that detects the operation displacement amount of the speed change operating device and outputs an operation displacement amount signal, The engine control unit includes a first safety determination section that determines a first safety state in which the shift operating device is in the neutral position in response to the neutral position signal, and a second safety determination section that determines a second safety state in which the shift operating device is in the neutral position based on the operation displacement amount, and when the engine control unit receives the start command with the first safety state and the second safety state determined, it starts the engine.

[0007] According to this configuration, a detector for detecting the operating position of the shifting device, which determines the shifting state of the transmission, and a detector for detecting the operating displacement of the shifting device are provided, and detection signals from each detector are input to the engine control unit. The engine control unit determines whether the vehicle is in an appropriate state for engine start based on the two detection signals, and starts the engine if the state is appropriate. In other words, a fail-safe system is realized in which the engine will not start unless the appropriate state for engine start is confirmed based on the detection signals from the two different detectors.

[0008] Modern vehicles are equipped with various control units (ECUs) interconnected via an in-vehicle LAN, and various detectors for detecting vehicle conditions send their detection signals to one or more control units as needed. To minimize communication path problems and noise interference, it is preferable that the detection signals from the two detectors described above, which determine whether the engine is properly started, be input directly to the engine control unit that controls the engine. For this reason, the present invention proposes that the neutral position signal and the operation displacement signal be sent directly to the engine control unit.

[0009] When determining whether the engine is in a proper state for starting based on the operation state of the gearshift operating device, if the proper state is not determined and the engine fails to start, the driver or inspector needs to understand the cause. Therefore, it is proposed that if at least one of the first safety state and the second safety state is indeterminate during the start operation of the starting operating device, at least one of an indeterminate event is notified and the indeterminate event is recorded. With this configuration, it is possible to determine whether at least one of the two detection signals for detecting the gearshift state is related to the cause of the engine not starting.

[0010] In a preferred embodiment of the present invention, the shift operating device is a swing-type shift lever, the neutral position detector is a contact-type (limit switch) or non-contact-type (proximity sensor) sensor that detects the shift lever when it reaches the neutral position, and the operation displacement detector is a potentiometer that detects the amount of swing displacement of the shift lever toward the neutral position. In this configuration, detectors that detect two events of the shift lever that create the shift state of the transmission, namely, a position detector (e.g., neutral position detection position) that detects whether the shift lever is located at a predetermined shift position (neutral position or shift position), and an operation displacement detector that detects the movement of the shift lever over time, are used to determine the appropriate state for engine start. Either detector can be used for other vehicle driving control, providing the advantage of using the same detector for both purposes. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. [Figure 2] FIG. 2 is a plan view of the driver's seat, passenger seat, and dashboard area. [Figure 3] FIG. 2 is a perspective view showing a speed change lever, a neutral position detector, and an operation displacement detector. [Figure 4] 3 is a functional block diagram showing the relationship between an engine control unit in a control system of a work vehicle, a detection signal of the speed change state of a transmission, and a start command. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] A multipurpose vehicle, which is an example of a work vehicle according to the present invention, will be described below. In the following description, with respect to the multipurpose vehicle, the direction of arrow F shown in the drawings will be referred to as the "front of the vehicle body," the direction of arrow B as the "rear of the vehicle body," the direction of arrow U as the "upper of the vehicle body," the direction of arrow D as the "lower of the vehicle body," the direction of arrow L as the "left of the vehicle body," and the direction of arrow R as the "right of the vehicle body."

[0013] As shown in Figure 1, the multipurpose vehicle is equipped with a pair of left and right front wheels 1 that can be driven and steered, a pair of left and right rear wheels 2 that can be driven, and a body frame 3 that is supported on the ground by the front wheels 1 and the rear wheels 2. A driver's section 9 is formed at the front of the body frame 3. A cargo bed 30 is equipped at the rear of the body frame 3. An engine E is mounted below the cargo bed 30. The driver's section 9 is surrounded by a ROP 9C.

[0014] As shown in FIGS. 1 and 2, the driver's section 9 is provided with a driver's seat 9A and a passenger seat 9B (see FIG. 2). A steering wheel 90 is disposed in front of the driver's seat 9A, and a dashboard 91 including an instrument panel 92 is disposed in front of the steering wheel 90. The instrument panel 92 is provided with a meter panel 93 as a display device, a touch panel, and various operation buttons. The driver's section 9 is also provided with manual operation devices such as an accelerator pedal 71 for adjusting the driving speed, a gear shift lever 72 for shifting gears, a starter operation device 73 for starting the engine, a 2WD / 4WD selector lever 74 for switching between 2WD and 4WD, and a brake pedal (not shown) for braking.

[0015] As shown in FIG. 3, in this embodiment, the shift lever 72 is displaceable along a guide groove formed in a guide plate 72a, and can switch the transmission T2 (see FIG. 4) between four shift positions: a low-speed position (designated L in FIG. 3), a high-speed position (designated H in FIG. 3), a neutral position (designated N in FIG. 3), and a reverse position (designated R in FIG. 3). The shift lever 72 is guided by the guide plate 72a and displaces vertically from the low-speed position to the neutral position, laterally from the right-side neutral position to the left-side neutral position, and further vertically from the left-side neutral position to the reverse position. The shift lever 72 is pivotable, and the low-speed position, high-speed position, neutral position, and reverse position of the shift lever 72 are selected by pivoting.

[0016] The shift lever 72 is capable of swinging about a first swing axis P1 and a second swing axis P2. The displacement of the shift lever 72 from the low-speed position to the high-speed position and then to the right-side neutral position is produced by swinging about the first swing axis P1. The displacement of the shift lever 72 from the right-side neutral position to the left-side neutral position is produced by swinging about the second swing axis P2. Furthermore, the displacement of the shift lever 72 from the left-side neutral position to the reverse position is produced by swinging about the first swing axis P1.

[0017] The neutral position detector 81 detects whether the gearshift lever 72 is in the neutral position. Here, the neutral position detector 81 is configured as a limit switch, and when it comes into contact with the gearshift lever 72 in the neutral position, it turns ON and outputs a neutral position signal. When the gearshift lever 72 moves out of the neutral position, the neutral position detector 81 turns OFF and does not output a neutral position signal.

[0018] Furthermore, the amount of swing of the shift lever 72 around the first swing axis P1, i.e., the amount of vertical displacement of the shift lever 72, is detected by an operation displacement detector 82. In this case, the operation displacement detector 82 is configured with a potentiometer, and outputs an operation displacement signal corresponding to the amount of vertical swing displacement of the shift lever 72. A predetermined value of the operation displacement signal determines whether the shift lever 72 is in the neutral position.

[0019] FIG. 4 is a functional block diagram showing the drive system of a work vehicle and a control system related to engine start-up. The drive system includes an engine E and a transmission T that changes the speed of power from the engine E and transmits it to the drive wheels (front wheels 1 and rear wheels 2). This work vehicle is selectable between 4WD and 2WD, so the drive wheels are front wheels 1 and rear wheels 2. The transmission T includes a continuously variable transmission T1 that first receives engine power, and a gear-type transmission T2 that changes the speed of the power from the continuously variable transmission T1. The continuously variable transmission T1 is configured as a CVT (belt-type continuously variable transmission). The transmission T2 has a low-speed position, a high-speed position, a neutral position, and a reverse position, and each of the speed positions is selected by a shift lever 72.

[0020] The core element of the control system related to engine starting is the engine control unit 4. A start command is input to the engine control unit 4 from a start operating device 73. A start control signal is output from the engine control unit 4 to a starter relay E1 attached to the engine E. The starter relay E1 is turned ON by the start control signal, starting the engine E. Various engine information such as engine speed and oil pressure state is input to the engine control unit 4 from the engine E, and various engine control signals such as ignition timing are given to the engine E from the engine control unit 4.

[0021] The engine control unit 4 is provided with a starting stability determination section 40, which includes a first safety determination section 41 and a second safety determination section 42. The first safety determination section 41 determines a first safety state in which the shift lever 72 is in the neutral position in response to a neutral position signal from the neutral position detector 81. The second safety determination section 42 determines a second safety state in which the shift lever 72 is in the neutral position in response to an operation displacement amount signal from the operation displacement amount detector 82. The starting stability determination section 40 determines a safety state in which engine starting is possible when the first safety determination section 41 determines the first safety state and the second safety determination section 42 determines the second safety state.

[0022] When the start operation device 73 is operated to start the engine while the start stability determination unit 40 has determined the safe state, a start command output from the start operation device 73 is given to the engine control unit 4. As a result, the engine control unit 4 gives a start control signal to the starter relay E1, and the engine E starts.

[0023] Even if a start command is given from the start operating device 73, if the start stability determining unit 40 has not determined a safe state, the engine control unit 4 does not give a start control signal to the starter relay E1. In this way, even if the start operating device 73 is operated to start the engine, if at least one of the first safety and the second safety is not determined and the start stability determining unit 40 has not determined a safe state, the engine E will not start, and the cause of the non-determination (non-determined event) will be recorded in memory.

[0024] The engine control unit 4 is connected to the meter control unit 8 via an in-vehicle LAN so as to be able to exchange data with the meter control unit 8. The meter control unit 8 acquires detection signals indicating the vehicle driving state, vehicle operation state, driver state, etc. from various sensors provided in the vehicle equipment group. Furthermore, the meter control unit 8 notifies the vehicle driving state, vehicle operation state, and driver state through various meters, lamps, and a touch panel 94 arranged on a meter panel 93. For example, when a start operation is performed on the starting operation tool 73, if the start stability determination unit 40 has not determined a safe state due to the above-mentioned non-deterministic event, the non-deterministic event, for example, a non-neutral state of the transmission T2, is notified through the meter panel 93.

[0025] [Another embodiment] (1) In the above-described embodiment, the neutral position detector 81 is configured as a contact-type limit switch, but other detectors such as a non-contact-type reed switch may be used. Similarly, the operation displacement detector 82 may also be configured as an encoder or other detector instead of a potentiometer.

[0026] (2) In the above-described embodiment, only the neutral state of the transmission T2 is considered as an engine start prevention, but other engine start prevention targets may be added using a similar technical configuration. For example, if a PTO device is provided, two types of detectors may be provided to detect the neutral state of the PTO clutch, and the start stability determination unit 40 may add the neutral state of the PTO clutch as a third safe state to the engine start prevention.

[0027] (3) In the above-described embodiment, the neutral position detector 81 and the operation displacement detector 82 detect the operation state of the shift lever 72 as the shift operating device, but instead, they may detect the operation state of a clutch operating body (such as a solenoid or cylinder) that performs clutch operation based on the operation of the shift lever 72. In other words, the shift operating device of the present invention also includes such a clutch operating body.

[0028] (4) In the above-described embodiment, the shift lever 72 is of a swing type. However, instead of this, a slide type shift lever 72, a rotating type shift lever 72, or a shift lever 72 that is any combination of a swing type, a slide type, and a rotating type may be used.

[0029] (5) In the above-described embodiment, a multipurpose vehicle is used as the work vehicle. However, instead of this, a brush cutter, a snow vehicle, an off-road vehicle, or the like may be used.

[0030] The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradiction arises. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0031] The present invention is applicable to a work vehicle equipped with a device that has a state for inhibiting engine start. [Explanation of symbols]

[0032] 4: Engine control unit 8: Meter control unit 40: Starting stability confirmation section 41: 1st safety confirmation section 42:Second safety confirmation section 72: Gear shift lever (gear shifting device) 73: Starting device 81: Neutral position detector 82: Operation displacement detector E: Engine E1: Starter relay T: Transmission T1: Continuously variable transmission T2: Transmission

Claims

1. The engine and a start operation tool that outputs a start command; a gear shift operating tool for operating a gear position of the gear shift device; an engine control unit that starts the engine based on the start command and the operation state of the speed change operating device; a neutral position detector that detects the neutral position of the speed change device and outputs a neutral position signal; an operation displacement amount detector that detects an operation displacement amount of the speed change operating device and outputs an operation displacement amount signal, The engine control unit includes: a first safety determining unit that determines a first safety state in which the speed change operating device is in the neutral position in response to the neutral position signal; a second safety determination unit that determines a second safety state in which the speed change operating device is in the neutral position based on the operation displacement amount; Contains, The engine control unit starts the engine when the start command is received in a state in which the first safety state and the second safety state are established.

2. 2. The work vehicle according to claim 1, wherein the neutral position signal and the operation displacement amount signal are sent directly to the engine control unit.

3. 2. The work vehicle according to claim 1, wherein, when at least one of the first safety state and the second safety state is uncertain during a start-up operation of the start-up operating device, at least one of an indeterminate event is notified and the indeterminate event is recorded.

4. 4. The work vehicle according to claim 1, wherein the shift operating device is a swing-type shift lever, the neutral position detector is a contact-type (limit switch) or non-contact-type (proximity sensor) sensor that detects the shift lever when it has reached the neutral position, and the operation displacement detector is a potentiometer that detects the amount of swing displacement of the shift lever toward the neutral position.

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