JP2017176068A - Riding lawn mower vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a configuration which facilitates automatic detection of an obstacle approaching a vehicle at the time of turning backward in a riding lawn mower vehicle with a configuration in which left and right wheels are independently driven to travel by a motor.SOLUTION: A riding lawn mower vehicle 10 includes: a driving source; a left wheel 12 and a right wheel 13; a transmission configured to independently drive the left wheel 12 and the right wheel 13 in response to power from the driving source in terms of a rotation direction and a rotation speed; caster wheels 15, 16 provided apart from the left wheel 12 and the right wheel 13 in a front-rear direction; a lawn mower 18; and two first sensors 50a, 50b disposed on both left and right sides in front of a rear end of the vehicle and configured to detect an obstacle located on the rear side.SELECTED DRAWING: Figure 2

Description

  The present invention includes a drive source, a left wheel and a right wheel that can be driven independently with respect to the rotation direction and the rotation speed, a caster wheel that is provided away from the left wheel and the right wheel in the front-rear direction, and mowing the lawn. The present invention relates to a riding lawnmower equipped with a machine.

  2. Description of the Related Art Lawn mower vehicles including lawn mowers that are driven to perform lawn mowing work are conventionally known. Further, in such a lawnmower vehicle, a lawnmower vehicle including left and right wheels, which are main drive wheels that are independently driven by a motor such as an electric motor or a hydraulic motor, and caster wheels has been considered.

  In addition, there is a lawnmower vehicle capable of self-running where an operator gets on and runs and controls the lawn mower on the vehicle, which is called a riding lawnmower vehicle. Examples of the lawn mower include a propeller type rotary blade type and a rotary winding blade type lawn mower rotary tool.

  Riding lawn mowers are used exclusively in so-called off-roads such as gardens, and move on the ground for mowing work.

  For example, Patent Document 1 describes a hybrid power unit equipped with an engine / generator integrated type in which a rotor is connected to an engine shaft of an internal combustion engine. A lawnmower vehicle exemplified as a power unit has a plurality of drive wheels connected to independent electric motors, and each drive wheel can be controlled independently at a variable speed, whereby the lawn mower vehicle can be started and stopped smoothly. It is stated that speed change and direction change can be performed. FIG. 4 of Patent Document 1 and the description thereof describe a lawnmower vehicle that can turn with a zero turning radius.

JP 2006-507789 A

  In the case of the vehicle described in FIG. 4 of Patent Document 1 and its description, the vehicle can turn by changing the speeds of the left and right rear wheels. Such a vehicle can make a sharp turn with a small turning radius. In this case, the driver turns backward while looking back. However, if there is a failure target in a blind area with respect to the driver's field of view, there is a possibility that it cannot be confirmed. In particular, when there is an obstacle object that is a person or an object in the lateral direction outside the driver's seat and in front of the rear end of the vehicle, it may not be confirmed. Accordingly, it is desired to realize a configuration that can easily detect an obstacle target when turning backward.

  If the obstacle target can be automatically detected when turning backward, for example, it is easy to avoid collision with the obstacle target. In the lawn mower vehicle, the obstacle target may be caught in the lawn mower when the obstacle target approaches the lawn mower when turning backward. If the obstacle target can be automatically detected when turning backward, it is easy to avoid the obstacle target being caught in the lawn mower when turning backward.

  An object of the present invention is to automatically detect an obstacle object approaching the vehicle when turning backwards in a riding-type lawn mower vehicle in which the left and right wheels can be independently driven in the rotational direction and the rotational speed. It is to realize an easy configuration.

  The riding lawn mower according to the present invention drives the left wheel and the right wheel independently of each other with respect to the rotation direction and the rotation speed by receiving power from the drive source, the left wheel and the right wheel, and the drive source. A riding lawnmower vehicle comprising a transmission configured to be possible, a caster wheel provided away from the left wheel and the right wheel in the front-rear direction, and a lawn mower, on the front side of the rear end of the vehicle Two first sensors arranged on both the left and right sides, and provided with two first sensors configured to detect a failure target located on the rear side.

  According to the riding lawn mower vehicle according to the present invention, in the configuration in which the left and right wheels can be driven independently with respect to the rotation direction and the rotation speed, the obstacle object approaching the vehicle is automatically detected when turning backward. Cheap. In particular, each of the two first sensors is disposed on both the left and right sides in front of the rear end of the vehicle, and is configured to detect a failure target located on the rear side. Unlike the case where sensors that can be detected are arranged, it is easy to detect a fault target located outside the left and right ends of the vehicle and ahead of the rear end of the vehicle.

1 is a perspective view of a riding lawn mower vehicle according to an embodiment of the present invention. It is a figure which shows the detection range of a 1st sensor seeing the vehicle of embodiment from upper direction. It is a block diagram which shows the characteristic structure of the vehicle of embodiment. It is the figure which looked at the power transmission structure of the power generation unit for left wheels and right wheels, and an engine from the upper side in the vehicle of embodiment. In the vehicle of an embodiment, it is a figure showing a hydraulic circuit of a power generation unit for left wheels and right wheels. In the vehicle of an embodiment, it is a schematic diagram showing the state of straight running. In the vehicle of an embodiment, it is a schematic diagram showing the state of the turning run to the front side. In the vehicle of an embodiment, it is a schematic diagram showing the state where it turns centering on one wheel of a right-and-left wheel. In the vehicle of an embodiment, it is a schematic diagram showing the state where it turns around the center between right-and-left wheels. In the vehicle of an embodiment, it is a schematic diagram showing inconvenience when turning backward. FIG. 3 is a diagram showing a state when the vehicle turns in the α direction from the state of FIG. 2 and a sensor detects an obstacle. FIG. 3 is a diagram showing a state when the vehicle turns in the β direction from the state of FIG. 2 and a sensor detects an obstacle. It is a block diagram which shows the characteristic structure of the riding type lawn mower vehicle of another example of embodiment which concerns on this invention. In the structure shown in FIG. 10, it is a figure corresponding to FIG. It is a block diagram which shows the characteristic structure of the riding type lawn mower vehicle of another example of embodiment which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, a configuration in which the left and right wheels of the riding lawn mower vehicle are driven by a hydraulic motor as a traveling motor will be mainly described. However, the traveling motor may be another motor such as an electric motor. In the following, the case where the wheels as the left and right main drive wheels are arranged on the rear side and the caster wheels are arranged on the front side will be described, but the wheels may be on the front side and the caster wheels may be on the rear side.

  The shape, the number, the arrangement relationship of components, and the like described below are examples for explanation, and can be appropriately changed according to the specification of the riding lawnmower. Also, in the following, the same reference numerals are given to the same elements in all the drawings, and overlapping descriptions are omitted or simplified.

  1 to 9 show a riding lawnmower according to an embodiment. Hereinafter, the riding lawnmower vehicle 10 is referred to as a vehicle 10. FIG. 1 is a perspective view of the vehicle 10. FIG. 2 is a diagram illustrating detection ranges of the first sensors 50a and 50b when the vehicle 10 is viewed from above. FIG. 3 is a block diagram showing a characteristic configuration of the vehicle 10. 4A is a view of the power transmission structure between the power generation units 26 and 27 for the left wheel 12 and the right wheel 13 and the engine 14 in the vehicle 10 as viewed from above. FIG. 4B is a diagram illustrating hydraulic circuits 28 and 29 of power generation units 26 and 27 for the left wheel 12 and the right wheel 13 in the vehicle 10.

  The vehicle 10 is a self-propelled off-road vehicle suitable for lawn mowing. The vehicle 10 includes a left wheel 12 and a right wheel 13, caster wheels 15 and 16, a lawn mower 18, two first sensors 50a and 50b, a tension switching actuator 43 (FIGS. 3 and 4A), and a control device. And a controller 60 (FIG. 3).

  The left wheel 12 and the right wheel 13 are rear wheels supported on the left and right sides on the rear side of the main frame 20 that is a vehicle body, and are main drive wheels. The main frame 20 is formed in a beam structure or the like from a metal such as a steel material. The main frame 20 includes side plate portions 20a and 20b extending substantially in the front-rear direction at both left and right ends, and a connecting portion 20c that connects the left and right side plate portions 20a and 20b. Between the rear end portions of the left and right side plate portions 20a and 20b, a driver seat 21 on which a driver vehicle sits is fixed on the upper side.

  In the main frame 20, left and right control levers 22 and 23 are supported so as to protrude from the front floor of the driver's seat 21. The tips of the control levers 22 and 23 are used by the driver to indicate the rotation direction and rotation speed of the left wheel 12 and the right wheel 13. Each control lever 22 and 23 is substantially L-shaped, and a grip portion 24 extending in the left-right direction is formed at the upper end portion. The grip portion 24 is operated by being gripped by the driver. Each of the control levers 22 and 23 can swing around an axis along the left-right direction at the lower end.

  The left wheel 12 and the right wheel 13 protrude outside the left and right outer ends of the side plate portions 20a and 20b of the main frame 20. The upper side of each wheel 12, 13 is at least partially covered with a wheel cover 25, and the inner end in the left-right direction of the wheel cover 25 is fixed to the side plate portions 20 a, 20 b.

  The two left and right caster wheels 15 and 16 are steered wheels supported by the front end portion of the main frame 20 and are front wheels. The left wheel 12 and the right wheel 13 are independently driven by a left hydraulic motor 30 (FIG. 4B) and a right hydraulic motor 31 (FIG. 4B), which will be described later, which are two traveling motors. Accordingly, the caster wheels 15 and 16 are provided away from the left wheel 12 and the right wheel 13 in the front-rear direction in the front-rear direction of the vehicle 10. Each of the caster wheels 15 and 16 can freely rotate 360 degrees or more around the axis in the vertical direction (the vertical direction in FIG. 1). Note that the number of caster wheels is not limited to a configuration in which two caster wheels are arranged in the vehicle, and only one or three or more caster wheels may be arranged in the vehicle. Below, the left wheel 12 and the right wheel 13 may be described as the left and right wheels 12 and 13.

  As shown in FIG. 4B, the left wheel 12 and the right wheel 13 can be independently driven by the transmission 11 with respect to the rotation direction and the rotation speed. The transmission 11 includes left and right power generation units 26 and 27. The power of the engine 14 as a drive source is input to the transmission 11, and the outputs of the left and right hydraulic pumps 32 and 33 are output to the drive shafts of the left and right wheels 12 and 13 via the reduction gear mechanisms 26b and 27b. Thereby, the transmission 11 receives the motive power from the engine 14, and comprises the left wheel 12 and the right wheel 13 so that it can drive independently about a rotation direction and a rotational speed, respectively. The left and right, fixed displacement hydraulic motors 30 and 31 constitute left and right power generation units 26 and 27, respectively. The left and right hydraulic motors 30 and 31 are connected to the drive shafts of the left wheel 12 and the right wheel 13, respectively. Each power generation unit 26, 27 generates power for wheels, and includes cases 26a, 27a and hydraulic circuits 28, 29 inside thereof. The hydraulic circuits 28 and 29 include swash plate type variable displacement hydraulic pumps 32 and 33, hydraulic motors 30 and 31 driven by pressure oil supplied from the hydraulic pumps 32 and 33, hydraulic pumps 32 and 33, and hydraulic pressure. And an oil passage 34 connecting the motors 30 and 31. The hydraulic motors 30 and 31 are, for example, fixed capacity types. The driven pulleys 35 are fixed to the drive shafts 32a and 33a of the hydraulic pumps 32 and 33, respectively, and are driven via a belt 36 by an engine 14 as a power source described later. The hydraulic pumps 32 and 33 function as an input unit of the transmission 11.

  The hydraulic pumps 32 and 33 include a left swash plate operation shaft 32b that is a left adjustment shaft that changes the tilt angle and direction of the movable swash plate by rotation, a right swash plate operation shaft 33b that is a right adjustment shaft, and a swash plate operation shaft. And swash plate operating levers 32c and 33c connected to 32b and 33b. The left swash plate operating shaft 32 b adjusts the pressure oil discharge amount of the left hydraulic pump 32. The right swash plate operating shaft 33 b adjusts the pressure oil discharge amount of the right hydraulic pump 33. The swash plate operation levers 32c and 33c are connected to the lower end portions of the left and right control levers 22 and 23 via links 37, respectively. As a result, the control levers 22 and 23 swing in the front-rear direction, whereby the swash plate operating shafts 32b and 33b rotate. Then, the tilt angle and direction of the movable swash plate of the hydraulic pumps 32 and 33 change. The discharge amount of the hydraulic pumps 32 and 33 is changed by changing the tilt angle of the movable swash plate. When the control levers 22 and 23 are largely tilted forward or backward, the discharge amounts of the hydraulic pumps 32 and 33 are increased. The left hydraulic motor 30 is driven by pressure oil supplied from the left hydraulic pump 32. The right hydraulic motor 31 is driven by pressure oil supplied from the right hydraulic pump 33. When the control levers 22 and 23 are tilted forward from the neutral state, the discharge directions of the hydraulic pumps 32 and 33 are regulated so as to rotate the hydraulic motors 30 and 31 to one side. When the control levers 22 and 23 are tilted backward from the neutral state, the discharge directions of the hydraulic pumps 32 and 33 are regulated so as to rotate the hydraulic motors 30 and 31 to the other side. The neutral state is a state in which the control levers 22 and 23 are automatically returned in a state where the control levers 22 and 23 are not grasped by the driver and no oil is discharged. Regarding the rotation direction of the hydraulic motors 30, 31, one side corresponds to rotation in the forward direction of the wheels 12, 13, and the other side corresponds to rotation in the reverse direction of the wheels 12, 13. Further, the swing angle positions of the control levers 22 and 23 are detected by lever potentiometers 38 and 39 which are swing angle detection units. Detection signals from the lever potentiometers 38 and 39 are transmitted to a controller 60 (FIG. 3) described later.

  4B, the charge oil passage C1 is connected to the two main oil passages S1, S2 connecting the hydraulic pumps 32, 33 and the hydraulic motors 30, 31. The charge oil passage C1 connects the main oil passages S1, S2 and the oil sump E via check valves F1, F2. The charge oil passage C1 is replenished with oil from the oil reservoir E in the main oil passage on the low pressure side of the main oil passages S1 and S2. Further, bypass valves 28a and 29a are connected between both the main oil passages S1 and S2 and the oil sump E. The bypass valves 28a and 29a are configured to be manually switchable between connection and disconnection between the main oil passages S1 and S2 and the oil sump E.

  The left and right wheels 12 and 13 are connected to the output shafts of the left and right hydraulic motors 30 and 31, respectively, through reduction gear mechanisms 26b and 27b constituting the power generation units 26 and 27 so that power can be transmitted. As will be described later, the vehicle 10 can travel straight and turn by independent control of the left and right wheels 12 and 13.

  The engine 14 is disposed on the rear side of the driver's seat 21 (FIG. 1) in the vehicle 10. As shown in FIG. 4A, in the engine 14, the drive shaft 14a along the vertical direction (the front and back direction in FIG. 4A) rotates about the vertical direction. A drive pulley 40 is fixed to the drive shaft 14a, and a belt 36 is stretched over the drive pulley 40 and two driven pulleys 35 provided in the left and right power generation units 26, 27. As a result, when the engine 14 is driven, the hydraulic pumps 32 and 33 are driven via the drive pulley 40, the belt 36 and the driven pulley 35. By operating the control levers 22 and 23, hydraulic oil is discharged from the hydraulic pumps 32 and 33, and the hydraulic motors 30 and 31 rotate. Further, the vehicle 10 is controlled such that the engine 14 is operated at a predetermined constant rotation speed when a start switch (not shown) is turned on by a user. An electric motor may be provided as a drive source for the hydraulic pumps 32 and 33.

  As will be described later, the left and right wheels 12 and 13 rotate in opposite directions at the same speed, so that the vehicle 10 suddenly rotates around a turning center position 70 (FIG. 2) located between the left wheel 12 and the right wheel 13. It is possible to turn.

  Further, as shown in FIG. 4A, the belt 36 is provided with a belt tension switching mechanism 41 so as to function as a clutch disposed between the output part of the drive source and the input part of the transmission 11, thereby The presence or absence is switched. The belt tension switching mechanism 41 includes a pressing pulley 42 that presses the belt 36 from the outer peripheral side, and a tension switching actuator 43 that switches the presence or absence of pressing force applied from the pressing pulley 42 to the belt 36. The pressing pulley 42 is supported by one end (left end in FIG. 4A) of the swing plate portion 44. The swing plate portion 44 is supported on the main frame 20 (FIG. 1) so as to be swingable about a vertical axis positioned at an intermediate portion of the swing plate portion 44. The tension switching actuator 43 includes a cylinder member 45, a rod 46 supported by the cylinder member 45 so as to be axially displaceable, and a linear solenoid (not shown) that changes the protruding length of the rod 46 from the cylinder member 45. ).

  The solenoid is disposed around the rod 46 inside the cylinder member 45, and operates so that the rod 46 protrudes from the cylinder member 45 by energizing the solenoid. The distal end portion of the rod 46 is coupled to the other end portion (the right end portion in FIG. 4A) of the swing plate portion 44. A spring 47 is attached to the swing plate portion 44, and the spring 47 imparts elasticity in a direction in which the pressing pulley 42 is pressed against the outer peripheral surface of the belt 36. Thereby, when the solenoid is energized, the protruding length of the rod 46 is increased, and the swing plate portion 44 swings in a direction in which the pressing pulley 42 is separated from the belt 36. For this reason, the tension of the belt 36 becomes 0, and the power transmission from the engine 14 to the hydraulic pumps 32 and 33 (FIG. 4B) is interrupted, so that the discharge amount of the hydraulic pumps 32 and 33 becomes 0 or minimal, and the hydraulic motor 30 , 31 (FIG. 4B) is stopped. At this time, power transmission by the clutch between the engine 14 and the transmission 11 is cut off. Accordingly, the rotation of the left and right wheels 12 and 13 connected to the hydraulic motors 30 and 31 so that power can be transmitted is also stopped. As a result, the traveling of the vehicle 10 is stopped, and when the vehicle 10 is turning, the turning is also stopped. The tension switching actuator 43 is controlled by a controller 60 (FIG. 3) described later, and connects and disconnects the clutch. The controller 60 operates the tension switching actuator 43 to stop the turning of the vehicle 10 when at least one of the failure targets P1, P2, and P3 (FIG. 2) is detected by first sensors 50a and 50b described later. . Thereby, it becomes difficult for the vehicle 10 to collide with the obstacle target when turning. When the solenoid is not energized, tension is generated in the belt 36 and power is transmitted from the engine 14 to the hydraulic pumps 32 and 33, so that power transmission by the clutch between the engine 14 and the transmission 11 is in the connected state. Become.

  Returning to FIG. 1, the lawn mower 18 is supported below the middle portion of the main frame 20 in the longitudinal direction. The lawn mower 18 is disposed between the caster wheels 15 and 16 and the left and right wheels 12 and 13 in the front-rear direction. The lawn mower 18 includes a lawn mowing blade (not shown) that is a lawn mowing rotary tool disposed inside a mower deck 19 that is a cover. The lawn mowing blade is covered on the upper side by the mower deck 19. The lawn mowing blade has a plurality of blade elements (not shown) that rotate about an axis oriented in the vertical direction (vertical direction in FIG. 1). As a result, the blade element rotates and the grass can be broken and trimmed. The lawn mowing blade is rotationally driven by a lawn mowing drive motor 48 (FIG. 3) controlled by a controller 60 (FIG. 3) described later. The lawn mower can be driven by receiving power from the engine 14 by, for example, placing a belt around a drive pulley fixed to the drive shaft of the engine 14 and a driven pulley fixed to the drive shaft of the lawn mowing blade. It is good also as a structure. The cut grass is discharged to one side of the vehicle 10 through a discharge port (not shown) provided on one side of the mower deck 19 in the left-right direction (left side in FIG. 1). A grass collection duct can be connected to the mower deck 19, and the cut grass can be collected in a grass collection tank connected to the grass collection duct.

  Further, both end portions in the left-right direction of the mower deck 19 protrude outward from the left and right ends at the middle portions in the front-rear direction of the left and right side plate portions 20a, 20b constituting the main frame 20, respectively. Further, each of the left and right wheels 12 and 13 is disposed behind the portion of the side plate portions 20a and 20b of the main frame 20 where the mower deck 19 protrudes outside and outside the left and right outer ends.

  As shown in FIG. 2, the two first sensors 50 a and 50 b are arranged separately on the left and right sides of the vehicle 10. Specifically, the two first sensors 50a and 50b are separately fixed and arranged at the left and right end portions that protrude outward from the side plate portions 20a and 20b of the main frame 20 in the upper portion such as the upper surface of the mower deck 19. Is done. Thus, the two first sensors 50 a and 50 b are arranged on both the left and right sides in front of the rear end of the vehicle 10. Each 1st sensor 50a, 50b is comprised so that the presence or absence of the obstruction or person who is an obstacle object located in the back may be detected. As such first sensors 50a and 50b, for example, a millimeter wave radar is used. At this time, the millimeter wave radar can detect the presence of the fault target in a preset detection area by reflecting the radio wave transmitted from the transmission unit on the fault target and receiving it on the reception unit. The first sensors 50a and 50b preferably have directivity in one direction in order to prevent the vehicle 10 itself from being detected. Furthermore, it is preferable that the first sensors 50a and 50b can measure the distance to the obstacle target. For example, in a millimeter wave radar, the distance to a fault target can be measured by receiving radio waves transmitted from one transmission unit with two reception units provided at different positions. In FIG. 2, detection areas of the first sensors 50 a and 50 b are indicated by hatched portions. The detection area extends to the rear side, but does not reach the vehicle 10. The detection signals of the first sensors 50a and 50b are transmitted to the controller 60 (FIG. 3). As the first sensors 50a and 50b, a laser radar, an ultrasonic sensor, an infrared sensor, or the like may be used.

  As shown in FIG. 3, the controller 60 includes a calculation unit such as a CPU and a storage unit such as a memory, and is configured by a microcomputer, for example. The controller 60 includes a backward turning determination unit 61, a turning stop unit 62, and a lawn mowing drive stop unit 63. The backward turning determination unit 61 determines whether or not the vehicle 10 is turning backward from the detection signals of the left and right lever potentiometers 38 and 39. For example, the rotation direction and rotation angle of the left and right wheels 12 and 13 are calculated from this detection signal. When the left and right wheels 12 and 13 rotate rearward and the rotation speeds of the left and right wheels 12 and 13 are different, it is determined that the vehicle 10 turns to the rear side. Also, when one of the left and right wheels rotates forward, and the other wheel rotates rearward, the absolute value of the rotational speed of the other wheel is greater than the absolute value of the rotational speed of one wheel. If it is larger, it is determined that the vehicle 10 turns sharply backward. In addition, when only one of the left and right wheels 12 and 13 rotates in the reverse direction, it is determined that the vehicle 10 makes a sudden turn backward. Such a sudden turn will be described later with reference to FIGS. When the absolute value of the ground movement speed between the rear rotating wheel that is the wheel that rotates to the rear side and the front rotating wheel that is the wheel that rotates to the front side is greater than zero, and the difference between the absolute values of both is zero A zero turn.

  The turning stop unit 62 is a case where the vehicle 10 is determined to be turning backward by the backward turning determination unit 61, and when the failure target is detected by at least one of the first sensors 50a and 50b, the vehicle 10 is stopped. Stop turning backwards. At this time, the turning stop unit 62 controls driving of the tension switching actuator 43 to stop driving of the left and right hydraulic motors 30 and 31 by setting the tension of the belt 36 to 0, that is, disengaging the clutch. Thereby, since the left and right wheels 12 and 13 are stopped, the backward turning is stopped. Further, the turning stop unit 62 turns the vehicle 10 backward when it is determined that the vehicle 10 is stopped and a failure target is detected by at least one of the first sensors 50a and 50b. Keep the stop. At this time, while stopping the turning of the vehicle 10 to the rear, the stop of the straight traveling to the rear may be maintained.

  Further, the lawn mowing drive stop unit 63 stops driving the lawn mowing drive motor 48 when the obstacle target is detected by at least one of the first sensors 50a and 50b and the lawn mowing drive motor 48 is driven. Let At this time, the lawn mowing drive stopping unit 63 controls the driving of the lawn mowing drive motor 48 to stop the rotation. The lawn mowing drive stop unit 63 stops driving the lawn mowing drive motor 48 when the object of failure is detected by at least one of the first sensors 50a and 50b and the lawn mowing drive motor 48 is stopped. To maintain.

  FIG. 5 is a schematic diagram showing a straight traveling state of the vehicle 10. FIG. 5 shows the positional relationship between the left and right wheels 12 and 13 and the caster wheels 15 and 16. As shown in FIG. 5, the vehicle 10 can travel straight by matching the rotational speeds of the left and right wheels 12 and 13 with the left and right hydraulic motors 30 and 31 (FIG. 4B). At this time, the ground movement speeds V1 and V2, which are the movement speeds of the ground contact positions with respect to the ground of the left and right wheels 12 and 13, coincide. A power source is not connected to the left and right caster wheels 15, 16, and the caster wheels 15, 16 are driven to rotate from the ground as the vehicle 10 is driven by driving the left and right wheels 12, 13. On the other hand, the vehicle 10 can turn by generating a difference in rotational speed between the left and right wheels 12 and 13.

  6A, 6B, and 6C show three examples of vehicle turning. 6A, 6B, and 6C also show the positional relationship between the left and right wheels 12 and 13 and the caster wheels 15 and 16, as in FIG. FIG. 6A is a schematic diagram illustrating a state of turning traveling forward in the vehicle 10. In FIG. 6A, the turning center position 70 is outside the left and right wheels 12 on the extension line in the axle direction of the left and right wheels 12 and 13 when viewed from above. At this time, the vehicle 10 turns relatively slowly.

  FIG. 6B is a schematic diagram showing the vehicle 10 turning around one of the left and right wheels 12 and 13. In FIG. 6B, the turning center position 70 is at the ground contact position of one wheel 12. Such a turn is called a belief turn, and the vehicle 10 turns more rapidly than in the case of FIG. 6A.

  FIG. 6C is a schematic diagram showing a state in which the vehicle 10 turns around the center between the left and right wheels 12 and 13. In FIG. 6C, the turning center position 70 is located at the center position between the left and right wheels 12 and 13 on the extension line in the axle direction of the left and right wheels 12 and 13 when viewed from above. The absolute values of the speeds V1, V2 of the left and right wheels 12, 13 are the same, but the direction of the speed V1 of one wheel 12 is opposite to the direction of the speed V2 of the other wheel 13. In this case, the vehicle 10 turns more rapidly than in the case of FIG. 6B. Such a turn is referred to as a zero turn (ZTR) because the turning turn or the turning radius is zero.

  FIG. 7 is a schematic diagram showing the inconvenience when the vehicle 10 turns backward. In FIG. 7, for easy understanding, the vehicle 10 is schematically illustrated by rectangles of a one-dot chain line G <b> 1 and a broken line G <b> 2. When the vehicle 10 is in the state of the one-dot chain line G1, the ground movement speed of the left and right wheels 12, 13 becomes V1, V2 in the reverse direction, and the absolute value of the ground movement speed V1 of the left wheel 12 is equal to the ground movement speed V2 of the right wheel 13. May be larger than absolute value. In this case, as indicated by the broken line G2, the vehicle 10 turns backward as indicated by the arrow α direction. In some cases, there is a failure target indicated by P near the front end of the vehicle 10 and outside the left side surface in the state of the one-dot chain line G1. At this time, the obstacle target P may not be seen from the driver of the driver's seat 21 or the driver may miss the obstacle target P. At this time, the vehicle 10 collides with the obstacle P in the state of the broken line G2 because the vehicle 10 continues to turn while spreading outward in the left-right direction on the front side. In the vehicle 10 of the embodiment shown in FIGS. 1 to 9, even when the obstacle target is located outside the vehicle 10 in the left-right direction as indicated by P <b> 1 and P <b> 2 in FIG. 2, of the two first sensors 50 a and 50 b, A failure target can be detected early by at least one of the first sensors 50a and 50b. In this state, turning to the rear of the vehicle 10 is stopped or stopped. Further, the driving of the lawn mower 18 is stopped or stopped.

  In addition, after the backward turning and the driving of the lawn mower 18 are stopped or stopped, in order to release the stop and stop maintenance, for example, the driver travels the vehicle 10 forward or the like to cause an obstacle. The target is removed from the detection area of the first sensors 50a and 50b. In this state, for example, the controller 60 may be reset by returning the left and right control levers 22 and 23 to the neutral state. This reset is that the controller 60 permits the vehicle to turn backward and drive the lawn mower.

  According to the vehicle 10 described above, in the configuration in which the left and right wheels 12 and 13 are independently driven by the hydraulic motors 30 and 31, the obstacle target that is relatively close to the vehicle 10 when turning backward is automatically detected. It's easy to do. For example, the field of view of the driver who gets in the driver's seat is the range indicated by the arrow Q in FIG. When there is an obstacle subject to being out of this range, in particular, being blocked by the engine bonnet 141, the driver needs to change his / her body later or get off the vehicle 10 to check. In particular, each of the two first sensors 50a and 50b is arranged on both the left and right sides in front of the rear end of the vehicle 10, and is configured to detect an obstacle target located relatively near the ground on the rear side. Is done. Thereby, unlike the case where a sensor capable of detecting the rear is arranged only at the rear end of the vehicle 10, it is easy to detect a fault target located outside the left and right ends of the vehicle 10 and in front of the rear end of the vehicle 10. And the turning of the vehicle 10 can be stopped at an early stage by detecting the failure target.

  In addition, as indicated by P3 in FIG. 2, there is a case where the failure target does not cover either of the detection areas of the left and right first sensors 50a and 50b. However, as shown in FIGS. 2 and 8, when the vehicle 10 turns backward in the direction of the arrow α with a zero turn or the like, the obstacle target P3 is detected by the left first sensor 50b in the state of FIG. Thereby, the turning of the vehicle 10 is stopped, and the vehicle 10 is prevented from colliding with the obstacle target P3. Moreover, since the driving of the lawn mower 18 is stopped when the failure target P3 is detected, the failure target P3 is prevented from being caught in the lawn mower 18. In FIG. 8, with respect to the ground movement speeds V1, V2 of the left and right wheels 12, 13, the speed corresponding to the forward direction is shown as positive, and the speed corresponding to the reverse direction is shown as negative.

  Further, as shown in FIG. 8 and the like, the left and right wheels 12 and 13 rotate in opposite directions, and the absolute value of the ground moving speed of the wheel rotating backward is equal to or larger than the absolute value of the ground moving speed of the wheel rotating forward. When this is the case, the vehicle 10 suddenly turns backward. In addition, the vehicle 10 rapidly turns rearward even when the rear wheel is turned in a backward direction, in which only one of the left and right wheels 12 and 13 rotates in the reverse direction and the other wheel stops. Will occur. As described above, when the vehicle 10 turns sharply backward, it becomes easy to approach the obstacle target at a position that is difficult to confirm. In order to prevent the vehicle from colliding with the obstacle, great attention is required from the driver. In the embodiment, when such a sharp turn is performed, the effect of the configuration including the first sensors 50a and 50b becomes remarkable.

  Although FIG. 8 illustrates the case where the vehicle 10 turns sharply in the direction of the arrow α, as shown in FIG. 9, the vehicle 10 may turn suddenly backward in the direction of the arrow β opposite to the arrow α with zero turn. At this time, in the state shown in FIG. 9, the failure target P3 is detected by the right first sensor 50b. Thereby, the turning of the vehicle 10 is stopped, and the driving of the lawn mower 18 is also stopped.

  FIG. 10 is a block diagram illustrating a characteristic configuration of a vehicle 10 according to another example of the embodiment. FIG. 11 is a diagram corresponding to FIG. 2 in the configuration shown in FIG. In the configurations shown in FIGS. 10 and 11, the second sensors 51 a and 51 b are arranged behind the first sensors 50 a and 50 b of the vehicle 10 in the configurations of FIGS. 1 to 9. Specifically, two second sensors 51a and 51b are fixed to the upper sides of the left and right wheel covers 25 that cover the upper sides of the left and right wheels 12 and 13, respectively. Each 2nd sensor 51a, 51b is comprised so that the failure target located in the back side may be detected similarly to 1st sensor 50a, 50b. In FIG. 11, detection areas of the second sensors 51a and 51b are shown by dotted areas. The detection area extends to the rear side, but does not reach the vehicle 10. Detection signals from the second sensors 51 a and 51 b are transmitted to the controller 60. In order to reduce the undetectable area, it is preferable that the detection areas of the two second sensors 51a and 51b partially overlap as shown in FIG. In order to reduce the undetectable area, it is preferable that the detection areas of the second sensors 51a and 51b partially overlap the detection areas of the first sensors 50a and 50b as shown in FIG.

  The controller 60 has a turning stop 62 (FIG. 3) and a lawn mowing drive stop 63 (FIG. 3). When at least one of the first sensors 50a and 50b and the second sensors 51a and 51b detects a failure target, the turning stop unit 62 stops turning the vehicle 10 backward or maintains the turning stop.

  Further, the lawnmower drive stop unit 63 stops driving or maintains the drive stop when at least one of the first sensors 50a and 50b and the second sensors 51a and 51b detects a failure target.

  According to said structure, since the area | region which can detect a failure target spreads, it is easy to detect automatically the failure target which approaches the vehicle 10 at the time of turning back. For example, even when obstacle targets P3 and P4 are located in the vicinity of the vehicle 10 behind the vehicle 10 and the obstacle targets cannot be detected by the first sensors 50a and 50b, the obstacle targets P3 and P3 are detected by the second sensors 51a and 51b. P4 is easy to detect. Other configurations and operations are the same as those in FIGS. 1 to 9.

  10 and 11, it is easy to detect the failure targets P3 and P4 located behind the rear end of the vehicle 10. For this reason, the controller 60 may be configured to stop the straight traveling to the rear side of the vehicle 10 when it is determined that the vehicle 10 is going straight ahead and when the obstacle targets P3 and P4 are detected.

  FIG. 12 is a block diagram showing a characteristic configuration of a vehicle 10 of another example of the embodiment according to the present invention. In the configuration of FIG. 12, the tension switching actuator is not provided in the configurations of FIGS. In the configuration of FIG. 12, the vehicle 10 includes a warning buzzer 72 disposed near the driver's seat. The warning buzzer 72 corresponds to a warning part. The operation of the warning buzzer 72 is controlled by the controller 60 and warns with sound that the obstacle object has been approached. The controller 60 activates the warning buzzer 72 when a failure target is detected by one or both of the left and right first sensors 50a and 50b. The operation of the warning buzzer 72 allows the driver to recognize that he or she has approached the obstacle, so that the left and right control levers 22 and 23 are returned to the neutral state to stop the backward turning or the straight traveling backward, A switch (not shown) for operating the lawn mower 18 is turned off. For this reason, vehicle safety can be ensured.

  In the configuration of FIG. 12, a warning light 73 may be disposed near the driver's seat 21 of the vehicle instead of or together with the warning buzzer 72. The warning light 73 also corresponds to the warning part. For example, the warning light 73 may be fixed near the feet of the driver's seat 21 in the vehicle. Further, the warning light 73 may be installed above the support portions of the caster wheels 15 and 16 that are easy to enter the field of view when looking forward. The operation of the warning light 73 is controlled by the controller 60 and warns that it has approached the failure target by lighting or blinking. The controller 60 activates the warning light 73 when a failure target is detected by one or both of the left and right first sensors 50a and 50b. By operating the warning light 73, the driver can recognize that he has approached the obstacle target. Other configurations and operations are the same as those in FIGS. 1 to 9.

  In the configuration of FIG. 12, two second sensors 51 a and 51 b can be provided as in the configurations of FIGS. 10 and 11. Further, in the configuration of FIGS. 1 to 9 or the configurations of FIGS. 10 and 11, the configuration including the tension switching actuator 43 may be configured such that a warning unit such as the warning buzzer 72 is provided. At this time, when the failure target is detected by at least one of the first sensors 50a and 50b and the second sensors 51a and 51b, the turning and driving of the lawn mower 18 are stopped or stopped and the warning unit is activated. Thereby, a warning can be given to the driver, and the suspension of the sudden turning operation can be promoted.

  Although the case where the controller 60 has both the turning stop unit 62 and the lawn mowing drive stop unit 63 has been described above, the controller may have only one of the turning stop unit 62 and the lawn mowing drive stop unit 63. Further, the vehicle 10 may be provided with a back switch for detecting that the left and right control levers 22 and 23 are in a region for instructing reverse travel in the vicinity of the left and right control levers 22 and 23, respectively. The back switch detection signal is transmitted to the controller 60. At this time, the controller 60 can determine whether or not the vehicle 10 is turning backward more stably by using not only the lever potentiometers 38 and 39 but also the detection signal of the back switch.

  In addition, direction indicating switches are attached to the left and right control levers 22 and 23, and two left and right direction indicating lights are provided at positions separated in the left and right direction at the front end portion of the vehicle 10 such as a position near the support portion of the caster wheels 15 and 16, for example. It can also be fixed. Each direction indicating light is configured to be able to blink when the left and right corresponding direction indicating switches are pressed. In such a configuration, it is possible to inform a person in the vicinity that the vehicle 10 turns to the front side or the rear side by blinking of the direction indication light, so that safer driving is possible. Further, the direction indication light may be used as the warning unit. Specifically, the controller simultaneously blinks or lights the left and right direction indicating lights when a failure target is detected by one or both of the left and right first sensors 50a and 50b.

  Moreover, although the case where the turning of the vehicle 10 was stopped by controlling the tension switching actuator 43 was described above, the turning of the vehicle 10 may be stopped by various other methods. For example, a throttle actuator that mechanically or electrically adjusts the opening of the throttle valve of the engine may be provided, and the controller 60 may control the drive of the throttle actuator to close the throttle valve to stop the turning. In addition, the configuration includes a bypass valve 28a, 29a (FIG. 4B) disposed between the hydraulic circuit of the power generation units 26, 27 and the oil reservoir, and a bypass actuator that simultaneously opens and closes the bypass valves 28a, 29a. Also good. Then, the controller 60 controls the drive of the bypass actuator to open the bypass valves 28a and 29a, that is, the main oil passages S1 and S2 are connected to the oil reservoir, thereby supplying oil to the hydraulic motor. May be stopped to stop turning. In addition, an actuator for driving the swash plate operation levers 32c and 33c connected to the swash plate operation shafts 32b and 33b of the hydraulic pumps 32 and 33 is provided to convert the operation amounts of the control levers 22 and 23 into electric signals. The actuator may be configured to be controlled by the controller 60. Then, the supply of oil to the hydraulic motor is stopped by stopping the discharge of oil from the hydraulic pumps 32 and 33 by rotating the swash plate operating shaft to neutralize the tilt angle of the movable swash plate. May be. Thereby, it becomes possible to stop turning.

  10 Riding Lawn Mower Vehicle (Vehicle), 11 Transmission, 12 Left Wheel, 13 Right Wheel, 14 Engine, 14a Drive Shaft, 15, 16 Castor Wheel, 18 Lawn Mower, 19 More Deck, 20 Main Frame, 20a, 20b Side Plate, 20c connecting part, 21 driver's seat, 22, 23 control lever, 24 gripping part, 25 wheel cover, 26, 27 power generation unit, 26a, 27a case, 26b, 27b reduction gear mechanism, 28, 29 hydraulic circuit, 28a, 29a Bypass valve, 30 left hydraulic motor, 31 right hydraulic motor, 32, 33 hydraulic pump, 32a, 33a drive shaft, 32b, 33b swash plate operation shaft, 32c, 33c swash plate operation lever, 34 oil passage, 35 driven pulley, 36 Belt, 37 links, 38, 39 Lever potentiometer, 40 drive Pulley, 41 Belt tension switching mechanism, 42 Press pulley, 43 Tension switching actuator, 44 Oscillating plate part, 45 Cylinder member, 46 Rod, 47 Spring, 48 Lawn mowing drive motor, 50a, 50b First sensor, 51a, 51b Second Sensor, 60 controller, 61 backward turning determination unit, 62 turning stop unit, 63 lawn mowing driving stop unit, 70 turning center position, 72 warning buzzer, 73 warning light, 141 engine bonnet.

Claims (6)

A driving source;
With left and right wheels,
A transmission configured to be able to drive the left wheel and the right wheel independently of each other with respect to the rotation direction and the rotation speed by receiving power from the drive source;
Caster wheels provided in the front-rear direction with respect to the left wheel and the right wheel;
Lawn mower,
A riding lawnmower vehicle comprising:
Riding lawn mower vehicle comprising two first sensors arranged on the left and right sides on the front side of the rear end of the vehicle, the two sensors being configured to detect an obstacle located on the rear side . The riding lawn mower according to claim 1,
The left and right ends of the mower deck that covers the upper side of the blade of the lawn mower project outward from the left and right ends of the longitudinal middle portion of the vehicle body, respectively.
The two first sensors are a riding-type lawn mower vehicle that is disposed on the upper side of the mower deck and is divided into left and right ends protruding from the vehicle body. The riding lawn mower according to claim 2,
Each of the left wheel and the right wheel is disposed behind the portion of the vehicle body where the mower deck protrudes outside and outside the left and right outer ends, and at least a part of the upper side is a wheel cover. Covered,
A riding lawnmower vehicle comprising two second sensors arranged on upper portions of the left and right wheel covers, the second sensors being configured to detect a failure target located on the rear side. The riding lawnmower vehicle according to any one of claims 1 to 3,
A riding-type lawn mower vehicle comprising: a control device that stops turning or maintains turning stop when the obstacle is detected by the first sensor. The riding lawn mower vehicle according to any one of claims 1 to 4,
A riding-type lawn mower vehicle, comprising: a control device that stops driving or maintains driving stop when the obstacle is detected by the first sensor. The riding lawnmower vehicle according to any one of claims 1 to 5,
A warning unit for warning that the obstacle object has been approached;
A riding lawn mower vehicle comprising: a control device that activates the warning unit when the failure target is detected by the first sensor.

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