Patent Description:
The present invention relates to a self-driving work vehicle.

<CIT> discloses a riding-type mowing machine including left and right rear wheels, a left travel lever that adjusts the speed of the left rear wheel, a right travel lever that adjusts the speed of the right rear wheel, and a brake apparatus. The brake apparatus operates by a brake lever or a brake pedal being manipulated. When a driver manipulates the left travel lever and the right travel lever to a neutral position and depresses the brake pedal, the brake apparatus operates as a parking brake. However, it is conceivable that the driver will forget to apply the parking brake when exiting the vehicle. It is also conceivable that a driver who plans to return to the work vehicle soon, and therefore opts not to apply the parking brake upon exiting the vehicle, does not actually return to the work vehicle soon, and instead leaves the work vehicle for a long period of time without the parking brake applied. Having been conceived of to solve the above-described problem to the greatest extent possible, the present invention provides a self-driving work vehicle in which a parking brake appropriately enters an operational state. <CIT> discloses a powered actuator system for mower parking brake system. <CIT> discloses an electrically released parking brake for zero turn radius mower. <CIT> discloses a parking brake system for a lap bar controlled zero turn radius mower. <CIT> discloses a mower with combined steering and brake levers.

A self-driving work vehicle of the present inventionis defined in claims <NUM>, <NUM> and <NUM>.

According to this configuration, the driver operates the parking brake (brake on) by moving the operation implement along the third path or the fourth path, instead of along the first path or the second path which are used to change the speed or heading of the vehicle body. In other words, the driver can operate the parking brake by switching from operating the operation implements in the paths for changing the vehicle speed, which are always maintained when driving, to operating the operation implements in different paths. That is, when operating the parking brake, there is no need to operate a dedicated parking brake operation implement, which simplifies the operation of the parking brake. This makes it possible to avoid a situation where the driver forgets to apply the parking brake when exiting the vehicle, and realizes a self-driving work vehicle in which the parking brake enters the operational state appropriately.

In one preferred embodiment of the present invention, in the self-driving work vehicle, movement of the left operation implement along the third path and movement of the right operation implement along the fourth path expand an exit passage for a driver to exit the self-driving work vehicle.

According to this configuration, the movement of the left operation implement along the third path and the movement of the right operation implement along the fourth path expands the exit passage for the driver, which makes it possible for the driver to exit smoothly. To exit the vehicle, the driver inevitably moves the left operation implement along the third path, and inevitably moves the right operation implement along the fourth path. The parking brake operates as a result, which even more reliably avoids a situation where the driver forgets to apply the parking brake when exiting the vehicle.

In one preferred embodiment of the present invention, in the self-driving work vehicle, the third path has a first detection position, the fourth path has a second detection position, and the controller is configured or programmed to cause the parking brake operating module to operate the parking brake in response to (i) the left operation implement being moved to the first detection position and (ii) the right operation implement being moved to the second detection position.

If the arrival of the operation implements at specific positions (the first detection position and the second detection position) in the movement paths is set in advance as a trigger to operate the parking brake, the parking brake can be operated in a reliable and stable manner. The arrival of the operation implements at the specific positions (the first detection position and the second detection position) can be detected easily and inexpensively using limit switches or the like.

In one preferred embodiment of the present invention, in the self-driving work vehicle, in an operational state of the parking brake, the parking brake becomes released in response to either or both of (i) the left operation implement being moved out of the first detection position and (ii) the right operation implement being moved out of the second detection position.

A parking brake in an operational (brake on) state must be released (brake off) when resuming driving. In order for the driver to board the vehicle and start driving, it is necessary for the driver to return the operation implements to the paths for adjusting the vehicle speed, and move the operation implements along those paths. In other words, it is necessary for the driver to move the operation implements to the paths for adjusting the vehicle speed from the specific positions (the first detection position and the second detection position) that served as triggers for operating the parking brake. According to this configuration, the driver moves the operation implements from the specific positions (the first detection position and the second detection position) to the paths for adjusting the vehicle speed, and the parking brake is released in the process of the operation implements moving, and there is thus no waste in the driver's movement to resume driving.

In the preferred embodiments of claim <NUM>, in the self-driving work vehicle, in an operational state of the parking brake, the parking brake becomes released in response to either or both of (i) the left operation implement being moved from a neutral position in a predetermined range along the first path and (ii) the right operation implement being moved from a neutral position in a predetermined ragne along the second path.

When parked on an incline or the like, there is a risk that the vehicle body will start moving when the parking brake is released. Accordingly, it is preferable to release the parking brake when the driver attempts to move the vehicle body, or just before. By setting the predetermined ranges appropriately, the parking brake can be released at the moment drive power is transmitted to the wheels, or just before drive power is transmitted to the wheels.

In the preferred embodiments of claim <NUM>, in the self-driving work vehicle, in an operational state of the parking brake, the parking brake becomes released in response to at least either of (i) the left operation implement being moved from a neutral position to exceed a predetermined movement rate along the first path and (ii) the right operation implement being moved from a neutral position to exceed a predetermined movement rate along the second path.

When the driver attempts to move the vehicle body, the operation implements are moved with a certain degree of acceleration. If the operation implements are slowly moved in a manner that is not such intentional operation, it is highly likely that parking brake need not be released. Such a configuration is therefore also advantageous.

Embodiments of the invention will now be described with reference to the accompanying drawings in which:.

Embodiments serving as examples of the present invention will be described hereinafter on the basis of the drawings. Note that in the following descriptions, with respect to a traveling vehicle body of a riding-type mowing machine (an example of a "self-driving work vehicle"), the direction of arrow F in <FIG> and <FIG> is a "vehicle body front", the direction of arrow B is a "vehicle body rear", the direction of arrow U in <FIG> is a "vehicle body top", the direction of arrow D is a "vehicle body bottom", the direction of arrow L in <FIG> is a "vehicle body left", and the direction of arrow R is a "vehicle body right".

As illustrated in <FIG> and <FIG>, the riding-type mowing machine includes a traveling vehicle body. The traveling vehicle body has a vehicle body frame <NUM>. The traveling vehicle body is equipped with a front wheel unit <NUM> including left and right front wheels that are idly rotatable and a rear wheel unit <NUM> capable of driving. The front wheels are caster wheels. The rear wheel unit <NUM> has a left rear wheel and a right rear wheel. A driver's section <NUM> is formed at the front of the traveling vehicle body, and the driver's section <NUM> has a driver's seat <NUM>. A travel motor unit <NUM> is provided below the driver's section <NUM>. The travel motor unit <NUM> includes a left motor and a right motor. The left motor supplies rotational drive power to the left rear wheel, and the right motor supplies rotational drive power to the right rear wheel. In other words, the left motor and the right motor supply rotational drive power independently to the left rear wheel and the right rear wheel, respectively. A battery pack <NUM> is provided at the rear of the traveling vehicle body. The battery pack <NUM> supplies power to the travel motor unit <NUM>. A mowing apparatus <NUM> is provided between the front wheel unit <NUM> and the rear wheel unit <NUM>. The mowing apparatus <NUM> is supported by the vehicle body frame <NUM> via a link mechanism <NUM>. The link mechanism <NUM> raises and lowers the mowing apparatus <NUM> relative to the traveling vehicle body. The mowing apparatus <NUM> includes a mowing blade housing <NUM> and a mowing blade <NUM>. The mowing blade <NUM> is provided within the mowing blade housing <NUM>, and is capable of being rotationally driven with a support shaft (not shown), which is parallel to the vertical direction of the vehicle body, serving as the rotational center.

As illustrated in <FIG> and <FIG>, the driver's section <NUM> is provided with an operation lever unit <NUM>. A driver adjusts the vehicle speed and heading of the traveling vehicle body while manipulating the operation lever unit <NUM>. The operation lever unit <NUM> includes a left operation lever 12a (an example of a left operation implement) and a right operation lever 12b (an example of a right operation implement). The left operation lever 12a and the right operation lever 12b are provided on respective sides of the driver's seat <NUM>. A floor plate is formed in front of the driver's seat <NUM>. The driver gets on or off the vehicle by passing between the left operation lever 12a and the right operation lever 12b, and the floor plate in front of the driver's seat <NUM>.

As illustrated in <FIG>, the left operation lever 12a and the right operation lever 12b both swing and move about a first swing axes P1, respectively. This swinging movement is movement in a front-back direction of the vehicle body, and will be called "longitudinal movement". The left operation lever 12a and the right operation lever 12b also swing and move about respective second swing axes P2. This swinging movement is movement in a lateral direction of the vehicle body, and will be called "lateral movement".

As illustrated in <FIG> and <FIG>, guide units <NUM> are provided to ensure the operation lever unit <NUM> moves (swings) in a stable manner. The left and right guide units <NUM> guide the respective base ends of the left operation lever 12a and the right operation lever 12b. Each guide unit <NUM> is a plate structure, with a longitudinal guide slot <NUM> and a lateral guide slot <NUM> formed in an upper surface of the guide unit <NUM>. The longitudinal guide slot <NUM> on the left side of the vehicle body guides the longitudinal movement of the left operation lever 12a. The longitudinal guide slot <NUM> on the right side of the vehicle body guides the longitudinal movement of the right operation lever 12b. The lateral guide slot <NUM> on the left side of the vehicle body guides the lateral movement of the left operation lever 12a. The lateral guide slot <NUM> on the right side of the vehicle body guides the lateral movement of the right operation lever 12b. The longitudinal guide slot <NUM> is connected to the lateral guide slot <NUM> in a central part of the longitudinal guide slot <NUM>.

As illustrated in <FIG>, the left operation lever 12a is guided by the longitudinal guide slot <NUM> to move longitudinally, and is guided by the lateral guide slot <NUM> to move laterally. Additionally, the right operation lever 12b is guided by the longitudinal guide slot <NUM> to move longitudinally, and is guided by the lateral guide slot <NUM> to move laterally. A path of the longitudinal movement of the left operation lever 12a will be called a first path L1, and a path of the longitudinal movement of the right operation lever 12b will be called a second path L2. A path of the lateral movement of the left operation lever 12a will be called a third path L3, and a path of the lateral movement of the right operation lever 12b will be called a fourth path L4. The first path L1 and the third path L3 connect at a junction point JP. The second path L2 and the fourth path L4 connect at a junction point JP. The first path L1 and the third path L3 are substantially orthogonal at the junction point JP. The second path L2 and the fourth path L4 are substantially orthogonal at the junction point JP.

As illustrated in <FIG>, a potentiometer <NUM> is provided near the base end of the left operation lever 12a. The potentiometer <NUM> on the left side of the vehicle body detects the longitudinal movement of the left operation lever 12a along the first path L1. Likewise, a potentiometer <NUM> is provided near the base end of the right operation lever 12b. The potentiometer <NUM> on the right side of the vehicle body detects the longitudinal movement of the right operation lever 12b along the second path L2. Each potentiometer <NUM> is connected to a controller <NUM>, and data of respective movement amounts of the left operation lever 12a and the right operation lever 12b are transmitted to the controller <NUM>.

Furthermore, a limit switch <NUM> is provided near the base end of the left operation lever 12a. The limit switch <NUM> on the left side of the vehicle body detects the left operation lever 12a being positioned in a specific position (a first detection position) set in the third path L3. Likewise, a limit switch <NUM> is provided near the base end of the right operation lever 12b. The limit switch <NUM> on the right side of the vehicle body detects the right operation lever 12b being positioned in a specific position (a second detection position) set in the fourth path L4. Each limit switch <NUM> is connected to the controller <NUM>, and detection signals from the limit switches <NUM> are transmitted to the controller <NUM>.

The travel motor unit <NUM> is connected to the controller <NUM> via a motor driver unit <NUM>. As described above, the travel motor unit <NUM> supplies rotational drive power to the rear wheel unit <NUM>, and the travel motor unit <NUM> includes a left motor and a right motor. The motor driver unit <NUM> includes a left driver for the left motor and a right driver for the right motor. A wheel control module <NUM> is configured in the controller <NUM>. Control signals from the controller <NUM> to the motor driver unit <NUM> are generated by the wheel control module <NUM>.

The controller <NUM> controls the rotation of the travel motor unit <NUM> on the basis of the longitudinal movement of the operation lever unit <NUM>. Specifically, the further the left operation lever 12a moves forward from the junction point JP in the first path L1, the higher the forward rotation speed of the left rear wheel becomes. Additionally, the further the left operation lever 12a moves rearward from the junction point JP in the first path L1, the higher the reverse rotation speed of the left rear wheel becomes. Likewise, the further the right operation lever 12b moves forward from the junction point JP in the second path L2, the higher the forward rotation speed of the right rear wheel becomes. Additionally, the further the right operation lever 12b moves rearward from the junction point JP in the second path L2, the higher the reverse rotation speed of the right rear wheel becomes. The position of the junction point JP of the left operation lever 12a, and the position of the junction point JP of the right operation lever 12b, are neutral positions where drive power is not supplied to the travel motor unit <NUM>. A state in which drive power is not supplied to the travel motor unit <NUM> will be called a "neutral state".

Each junction point JP functions as a neutral position where the transmission of rotational drive power to the rear wheel unit <NUM> is set to zero. Accordingly, when the left operation lever 12a is positioned in the third path L3, the transmission of rotational drive power to the left rear wheel is zero and the neutral state is maintained. Likewise, when the right operation lever 12b is positioned in the fourth path L4, the transmission of rotational drive power to the right rear wheel is zero and the neutral state is maintained.

As illustrated in <FIG>, a parking brake <NUM> is interposed between the travel motor unit <NUM> and the rear wheel unit <NUM>. The parking brake <NUM> includes a left brake and a right brake. The left brake is interposed between the left motor and the left rear wheel. The right brake is interposed between the right motor and the right rear wheel. The parking brake <NUM> is connected to the controller <NUM> via a brake driver <NUM>. A parking brake operating module <NUM> is configured in the controller <NUM>. Control signals from the controller <NUM> to the brake driver <NUM> are generated by the parking brake operating module <NUM>. In this embodiment, the parking brake <NUM> is constituted by an electromagnetic brake.

In this embodiment, a variable traveling power supply apparatus PSU supplies rotational drive power to the rear wheel unit <NUM> on the basis of the movement position of the operation lever unit <NUM>. The variable traveling power supply apparatus PSU is constituted by the travel motor unit <NUM>, the parking brake <NUM>, and a transmission mechanism (not shown). The transmission mechanism includes a transmission shaft, transmission gears, and the like.

When the left operation lever 12a reaches the first detection position and the left-side limit switch <NUM> turns on, and the right operation lever 12b reaches the second detection position and the right-side limit switch <NUM> turns on, the parking brake operating module <NUM> causes the left brake and the right brake of the parking brake <NUM> to operate (brake on). As a result, the parking brake <NUM> operates and the traveling vehicle body enters a parked state.

As illustrated in <FIG>, the left operation lever 12a rises from the left side of the driver's seat <NUM>, and bends toward a centerline of the vehicle body in the lateral direction of the vehicle body. A grip is formed in a tip region of the bent part of the left operation lever 12a. Likewise, the right operation lever 12b rises from the right side of the driver's seat <NUM>, and bends toward the centerline of the vehicle body in the lateral direction of the vehicle body. A grip is formed in a tip region of the bent part of the right operation lever 12b. In other words, the grip on the left operation lever 12a and the grip on the right operation lever 12b face each other, and interfere with the exit passage of the driver exiting the driver's seat <NUM>. When the left operation lever 12a moves laterally outward from the vehicle body along the third path L3 and the right operation lever 12b moves laterally outward from the vehicle body along the fourth path L4, a gap between the grip on the left operation lever 12a and the grip on the right operation lever 12b widens. This opens the exit passage for the driver to exit the vehicle. Accordingly, when the driver exits the vehicle, the left operation lever 12a moves laterally outward from the vehicle body along the third path L3 and the right operation lever 12b moves laterally outward from the vehicle body along the fourth path L4. It would be convenient for the parking brake <NUM> to operate at the point in time when the left operation lever 12a and the right operation lever 12b move laterally outward from the vehicle body.

The method of releasing this parking brake <NUM> will be described in the following first to sixth embodiments.

A first embodiment of releasing the parking brake will be described first. The parking brake operating module <NUM> is configured or programmed to release the parking brake <NUM> (brake off) when the left operation lever 12a of the operation lever unit <NUM> being moved out of the first detection position in the third path L3 has been detected from the detection signal from the limit switch <NUM> or when the right operation lever 12b being moved out of the second detection position in the fourth path L4 has been detected from the detection signal from the limit switch <NUM>.

A second embodiment of releasing the parking brake will be described next. The parking brake operating module <NUM> is configured or programmed to release the parking brake <NUM> (brake off) when the left operation lever 12a of the operation lever unit <NUM> being moved out of the first detection position in the third path L3 has been detected from the detection signal from the limit switch <NUM> and when the right operation lever 12b being moved out of the second detection position in the fourth path L4 has been detected from the detection signal from the limit switch <NUM>.

A third embodiment of releasing the parking brake will be described next. Unlike the first and second embodiments, in this embodiment, the parking brake <NUM> is not released by behavior of the left operation lever 12a in the third path L3 or behavior of the right operation lever 12b in the fourth path L4. The parking brake <NUM> is released by behavior of the left operation lever 12a in the first path L1 or by behavior of the right operation lever 12b in the second path L2. Such behavior of the operation lever unit <NUM> is detected from detection signals from the potentiometers <NUM>. Specifically, the parking brake operating module <NUM> is configured or programmed to release the parking brake <NUM> in response to movement in a predetermined range along the first path L1 as the behavior of the left operation lever 12a, movement in a predetermined range along the second path L2 as the behavior of the right operation lever 12b, or both, when the parking brake <NUM> is in an operational state. This predetermined range is predetermined angular movement in a forward direction or a rearward direction from the junction point JP.

A fourth embodiment of releasing the parking brake will be described next. This embodiment is a variation on the third embodiment. In the fourth embodiment, the parking brake operating module <NUM> is configured or programmed to release the parking brake <NUM> in response to movement of the left operation lever 12a along the first path L1 from the neutral position (the junction point JP) exceeding a predetermined movement rate, movement of the right operation lever 12b along the second path L2 from the neutral position exceeding a predetermined movement rate, or both, when the parking brake <NUM> is in an operational state. The movement rate of the left operation lever 12a indicates the movement amount of the left operation lever 12a per unit of time. The movement rate of the right operation lever 12b indicates the movement amount of the right operation lever 12b per unit of time. Note that the movement rate may indicate an acceleration of the movement of each of the left operation lever 12a and the right operation lever 12b. The movement rate is calculated by a differential calculator of the parking brake operating module <NUM>, to which the signals from the potentiometers <NUM> are input. The predetermined movement rate is a pre-set threshold for the movement amount. The predetermined movement rate is normally set on the basis of the operation behavior on the operation lever unit <NUM> when the driver begins driving from a parked state.

A fifth embodiment of releasing the parking brake will be described next. This embodiment is similar to the third embodiment. In the third embodiment, the parking brake operating module <NUM> releases the parking brake <NUM> in response to movement of the left operation lever 12a in a predetermined range along the first path L1, movement of the right operation lever 12b in a predetermined range along the second path L2, or both. In contrast, in the fifth embodiment, the parking brake operating module <NUM> is configured or programmed to release the parking brake <NUM> in response to movement of the left operation lever 12a in a predetermined range along the third path L3, movement of the right operation lever 12b in a predetermined range along the fourth path L4, or both. Accordingly, in the fifth embodiment, as illustrated in <FIG>, lateral potentiometers <NUM> are provided for detecting lateral movement (movement along the third path L3 and the fourth path L4), which is swinging movement of the left operation lever 12a and the right operation lever 12b of the operation lever unit <NUM> about the respective second swing axes P2. These lateral potentiometers <NUM> are connected to the controller <NUM>, and the parking brake operating module <NUM> can sequentially detect lateral movement of the left operation lever 12a and the right operation lever 12b. Accordingly, the parking brake operating module <NUM> can release the parking brake <NUM> by detecting lateral movement of a predetermined angle from the neutral position of the operation lever (the junction point JP).

A sixth embodiment of releasing the parking brake will be described next. This embodiment is a variation on the fifth embodiment. In the sixth embodiment, the parking brake operating module <NUM> is configured or programmed to release the parking brake <NUM> in response to movement of the left operation lever 12a along the third path L3 from the neutral position exceeding a predetermined movement rate, movement of the right operation lever 12b along the fourth path L4 from the neutral position exceeding a predetermined movement rate, or both, when the parking brake <NUM> is in an operational state. The movement rate of the left operation lever 12a indicates the displacement amount of the left operation lever 12a per unit of time. The movement rate of the right operation lever 12b indicates the movement amount of the right operation lever 12b per unit of time. Note that the movement rate may indicate an acceleration of the movement of each of the left operation lever 12a and the right operation lever 12b. The movement rate is calculated by a differential calculator of the parking brake operating module <NUM>, to which the signals from the lateral potentiometers <NUM> are input. The predetermined movement rate is a pre-set threshold for the movement amount. The predetermined movement rate is normally set on the basis of the operation behavior on the operation lever unit <NUM> when the driver begins driving from a parked state.

The present invention is not limited to the configurations described as examples in the foregoing embodiments (the first to sixth embodiments of the parking brake <NUM>), and examples of other representative embodiments of the present invention will be given hereinafter.

Claim 1:
A self-driving work vehicle, comprising:
a front wheel unit (<NUM>);
a rear wheel unit (<NUM>) including a left rear wheel and a right rear wheel;
a variable traveling power supply apparatus (PSU) that supplies rotational drive power to the left rear wheel and the right rear wheel independently, the variable traveling power supply apparatus (PSU) including an electric left motor capable of supplying rotational drive power to the left rear wheel and an electric right motor capable of supplying rotational drive power to the right rear wheel;
a left operation implement (12a) movable along a first path (L1) to adjust a rate of the rotational drive power to be supplied to the left rear wheel from the variable traveling power supply apparatus (PSU);
a right operation implement (12b) movable along a second path (L2) to adjust a rate of the rotational drive power to be supplied to the right rear wheel from the variable traveling power supply apparatus (PSU);
a parking brake (<NUM>) provided for the variable traveling power supply apparatus (PSU) which includes the electric left motor and the electric right motor; and
a controller (<NUM>) configured or programmed to cause a parking brake operating module (<NUM>) to operate the parking brake (<NUM>) in response to (i) the left operation implement (12a) being moved to a third path (L3) branching from the first path (L1) and (ii) the right operation implement (12b) being moved to a fourth path (L4) branching from the second path (L2).