Patent Description:
A known example of work vehicles such as the above is the work vehicle disclosed in document <CIT>. The work vehicle disclosed in such document is capable of automatically steering the travel vehicle body so that the travel vehicle body travels on a target travel path. The work vehicle disclosed in document <CIT> includes a motor configured to drive a steering shaft to rotate (namely, the "steering motor (<NUM>)" in the document). The work vehicle is arranged such that the motor is provided at a base portion of a steering wheel (namely, the "steering wheel (<NUM>)" in the document). A work vehicle is also known from <CIT>. Another work vehicle is known from <CIT>, <CIT>, <CIT> or <CIT>.

Conventional art involves the following issue <NUM>:
The work vehicle disclosed in document <CIT> has a limited space around the base portion of the steering wheel. It is not easy to place a motor in the space.

The above circumstances have led to a demand for a work vehicle having a space that easily accommodates a motor for automatic steering.

Conventional art involves the following issue <NUM>:
The work vehicle disclosed in document <CIT> has a limited space around the base portion of the steering wheel. If the driving force of the motor is to be transmitted to the steering shaft
with use of a gear mechanism contained in a gear case, it is not easy to place such a gear case in the space.

The above circumstances have led to a demand for a work vehicle having a space that easily accommodates a gear case for automatic steering.

The description below deals with a means to solve issue <NUM>.

The present invention characteristically includes: a steering wheel for steering a travel vehicle body of the work vehicle; a steering shaft connected with the steering wheel, extending downward from the steering wheel, and configured to be rotated with use of the steering wheel; a steering tower for which the steering wheel and the steering shaft are provided; and an automatic steering mechanism configured to automatically steer the travel vehicle body so that the travel vehicle body travels on a target travel path, wherein the automatic steering mechanism includes a motor configured to drive the steering shaft to rotate, the automatic steering mechanism is present in the steering tower, and the motor is present under the steering wheel and adjacent laterally to the steering shaft. The work vehicle comprises an automatic steering switching lever for switching between starting and ending automatic steering and a forward-reverse switching lever for switching a travel direction of the vehicle body between a forward travel and a reverse travel, wherein the automatic steering switching lever and the forward-reverse switching lever are positioned at an upper portion of the steering tower and below the steering wheel, and are present on the first side in the left-right direction of the vehicle body with respect to the rotation axis, and are present at respective positions different from each other in a front-back direction of the vehicle body.

The above characteristic arrangement keeps a relatively large open space present under the steering wheel and adjacent laterally to the steering shaft. The above characteristic arrangement allows the motor to be placed in a space present under the steering wheel and adjacent laterally to the steering shaft. This makes it easy to find a space for the motor.

If the motor is placed under the steering wheel and in front or back of the steering shaft, the steering tower will be larger in the front-back direction and may disturb the driver. With the above characteristic arrangement, however, the motor is present under the steering wheel and adjacent laterally to the steering shaft. The steering tower is thus not larger in the front-back direction and does not disturb the driver.

The present invention may preferably be arranged such that the automatic steering mechanism further includes (i) a gear mechanism configured to transmit a driving force of the motor to the steering shaft and (ii) a gear case containing the gear mechanism, and the motor and the gear case are arranged vertically.

The above characteristic arrangement places the motor and the gear case close to each other in the up-down direction. This allows the motor and the gear case to be placed in a compact manner.

The present invention may preferably be arranged such that the motor is supported by the gear case.

The above characteristic arrangement allows the gear case to be used as a member for supporting the motor. This eliminates the need to include a dedicated member for supporting the motor.

The present invention may preferably be arranged such that the steering tower is swingable about a swing axis extending in a left-right direction of the travel vehicle body, and the work vehicle further includes a tilt mechanism configured to adjust a position of the steering tower about the swing axis.

The above characteristic arrangement allows the position of the steering wheel to be adjusted in accordance with the build of the driver. The above characteristic arrangement also allows a work vehicle to be produced that includes both an automatic steering mechanism and a tilt mechanism and that is thus highly convenient.

The present invention characteristically includes: a steering wheel for steering a travel vehicle body of the work vehicle; a steering shaft connected with the steering wheel, extending downward from the steering wheel, and configured to be rotated with use of the steering wheel; a steering tower for which the steering wheel and the steering shaft are provided; and an automatic steering mechanism configured to automatically steer the travel vehicle body so that the travel vehicle body travels on a target travel path, wherein the automatic steering mechanism includes (i) a motor configured to drive the steering shaft to rotate, (ii) a gear mechanism configured to transmit a driving force of the motor to the steering shaft, and (iii) a gear case containing the gear mechanism, the automatic steering mechanism is present in the steering tower, and the gear case is present under the steering wheel and shifted to a first side in a left-right direction of the travel vehicle body with respect to a rotation axis of the steering wheel. The work vehicle comprises an automatic steering switching lever for switching between starting and ending automatic steering and a forward-reverse switching lever for switching a travel direction of the vehicle body between a forward travel and a reverse travel, wherein the automatic steering switching lever and the forward-reverse switching lever are positioned at an upper portion of the steering tower and below the steering wheel, and are present on the first side in the left-right direction of the vehicle body with respect to the rotation axis, and are present at respective positions different from each other in a front-back direction of the vehicle body.

The above characteristic arrangement keeps a relatively large open space under the steering wheel and next to the steering shaft. The above characteristic arrangement allows the gear case to be placed in a space under the steering wheel and on one side of the steering shaft in the left-right direction of the vehicle body. This makes it easy to find a space for the gear case. The above characteristic arrangement also allows a member other than the gear case to be placed under the steering wheel and on the other side of the steering shaft in the left-right direction of the vehicle body. This makes it possible to effectively utilize a space next to the steering shaft.

If the gear case is placed under the steering wheel and shifted to the front or back side of the rotation axis of the steering wheel, the steering tower will be larger in the front-back direction and may disturb the driver. With the above characteristic arrangement, however, the gear case is present under the steering wheel and shifted to one side of the rotation axis of the steering wheel in the left-right direction of the vehicle body. The steering tower is thus not larger in the front-back direction and does not disturb the driver.

The present invention may preferably be arranged such that the motor and the gear case are arranged vertically.

The present invention may preferably be arranged such that the gear case has a thickness in an up-down direction which thickness is equal to or substantially equal to a thickness of the motor in the up-down direction.

A gear case tends to have a thickness in the up-down direction which thickness is larger than the thickness of a motor in the up-down direction. With the above characteristic arrangement, however, the gear case is thinner. This saves space for the gear case.

The present invention may preferably be arranged such that the motor is supported by a portion of the gear case which portion is present on the first side of the rotation axis.

The above characteristic arrangement allows the gear case to be used as a member for supporting the motor. This eliminates the need to include a dedicated member for supporting the motor. The above characteristic arrangement allows a large portion of the gear case to be present on one side of the rotation axis of the gear case in the left-right direction of the vehicle body to support the motor.

The forward-reverse switching lever may extend upward from a height below the gear case to a height between an upper end and a lower end of the steering wheel.

The above characteristic arrangement places an upper portion (that is, the grip portion) of the forward-reverse switching lever closely to the steering wheel. This allows the driver to, for operation of the forward-reverse switching lever, move a hand only over a short distance from the steering wheel to the forward-reverse switching lever. This improves the operability of the forward-reverse switching lever.

The present invention may preferably further include: a forward-reverse switch configured to switch the travel direction of the travel vehicle body between the forward travel and the reverse travel in accordance with an operation position of the forward-reverse switching lever, wherein the forward-reverse switch is present under a portion of the gear case which portion is present on the first side of the rotation axis.

As described above, the gear case is shifted to one side of the rotation axis of the steering wheel in the left-right direction of the vehicle body. This allows for a large space under the gear case and on that side of the rotation axis in the left-right direction of the vehicle body as compared to the other side of the rotation axis in the left-right direction of the vehicle body. The above characteristic arrangement places the forward-reverse switch in a large space under a portion of the gear case which portion is present on one side of the rotation axis in the left-right direction of the vehicle body. This makes it easy to find a space for the forward-reverse switch.

The description below deals with an embodiment of the present invention with reference to drawings.

<FIG> and <FIG> each illustrate a tractor (work vehicle). The tractor includes a travel vehicle body <NUM>. The travel vehicle body <NUM> is, for example, of a four-wheel drive type. The travel vehicle body <NUM> is provided with a pair of left and right drivable and steerable front wheels 2F and a pair of left and right drivable rear wheels 2B. The travel vehicle body <NUM> is also provided with a pair of left and right fenders <NUM> that cover the pair of left and right rear wheels 2B, respectively.

The travel vehicle body <NUM> has a front half provided with a motor section <NUM>. The motor section <NUM> includes an engine E and a bonnet <NUM> that covers the engine E. The travel vehicle body <NUM> has a rear half provided with a driver section <NUM> for a driver to get in. The driver section <NUM> includes a driver's seat <NUM> for a driver to sit on and a front panel <NUM> in front of the driver's seat <NUM>. The travel vehicle body <NUM> is provided with a ROPS <NUM> near the driver's seat <NUM>. The travel vehicle body <NUM> has a rear end provided with a link mechanism <NUM> to which a work device (not shown in the drawings) such as a rotary tiller device is attachable.

The tractor is provided with a GPS antenna unit <NUM> and an inertia measuring device (not shown in the drawings). The GPS antenna unit <NUM> is configured to receive positional information from GPS (global positioning system) satellites and determine the position of the travel vehicle body <NUM> on the basis of the positional information received. The GPS antenna unit <NUM> is supported by an upper portion of the ROPS <NUM> at such a position as to have a left-right center that coincides with the left-right center of the vehicle body. The inertia measuring device is configured to measure inertia information (such as information on a yaw angle, a pitch angle, and a roll angle) of the travel vehicle body <NUM>. The tractor includes an automatic steering mechanism <NUM> (see <FIG>) configured to, on the basis of (i) the position of the travel vehicle body <NUM> as determined by the GPS antenna unit <NUM> and (ii) the inertia information of the travel vehicle body <NUM> as measured by the inertia measuring device, automatically steer the travel vehicle body <NUM> so that the travel vehicle body <NUM> travels on a target travel path.

As illustrated in <FIG>, the front panel <NUM> includes a meter panel <NUM>, a monitor <NUM> (display device), and a steering tower <NUM>. The steering tower <NUM> is provided with, for example, a steering wheel <NUM>. The meter panel <NUM> is positioned under a front portion of the steering wheel <NUM>. The meter panel <NUM> is provided with, for example, a fuel meter, an engine tachometer, a water temperature meter, a liquid crystal display section, and various lamps. The monitor <NUM> is positioned above the meter panel <NUM> and in front of the steering wheel <NUM>. The monitor <NUM> is configured to display information on automatic steering of the travel vehicle body <NUM>. The monitor <NUM> functions as a guidance monitor for automatic steering of the travel vehicle body <NUM>.

The steering tower <NUM> is positioned in front of the driver's seat <NUM>. The steering tower <NUM> is provided with a steering wheel <NUM>, a steering shaft <NUM>, a steering post <NUM>, an automatic steering switching lever <NUM>, a forward-reverse switching lever <NUM>, setting switches <NUM>, a switch <NUM>, and an automatic steering mechanism <NUM>. Members such as the steering post <NUM> and the automatic steering mechanism <NUM> are covered by a steering cover <NUM>.

The steering tower <NUM> is supported by a support frame <NUM> via the steering post <NUM> in such a manner as to be swingable about a swing axis X1 extending in the left-right direction of the vehicle body. The tractor is provided with a tilt mechanism <NUM> configured to adjust the position of the steering tower <NUM> about the swing axis X1. The front panel <NUM> has a lower portion provided with a tilt pedal <NUM> with which to operate the tilt mechanism <NUM>. Pressing the tilt pedal <NUM> with a foot allows the position of the steering tower <NUM> to be adjusted with use of the tilt mechanism <NUM>. Releasing the pressed tilt pedal <NUM> causes the position of the steering tower <NUM> to be fixed.

The steering wheel <NUM> is for use to steer the travel vehicle body <NUM>. The steering shaft <NUM> is connected with the steering wheel <NUM> and extends downward from the steering wheel <NUM>.

The steering shaft <NUM> is supported by the steering post <NUM> in such a manner as to be rotatable about the axis of the steering shaft <NUM> (that is, the rotation axis of the steering wheel <NUM>) Z1 with use of the steering wheel <NUM>. The steering post <NUM> includes (i) an upper insertion portion <NUM> through which an upper portion of the steering shaft <NUM> is present and by which the upper portion is supported, (ii) a lower insertion portion <NUM> through which a lower portion of the steering shaft <NUM> is present and by which the lower portion is supported, and (iii) a base portion <NUM> supporting the lower insertion portion <NUM>. The base portion <NUM> is supported by the support frame <NUM> in such a manner as to be swingable about the swing axis X1.

The automatic steering switching lever <NUM> is for use to start or end automatic steering of the travel vehicle body <NUM> and otherwise. The forward-reverse switching lever <NUM> is for use to switch the travel direction of the travel vehicle body <NUM> between a forward travel and a reverse travel. The automatic steering switching lever <NUM> and the forward-reverse switching lever <NUM> are positioned at an upper portion of the steering tower <NUM> and below the steering wheel <NUM>. The automatic steering switching lever <NUM> and the forward-reverse switching lever <NUM> are both positioned on one side of the rotation axis Z1 of the steering wheel <NUM> in the left-right direction of the vehicle body (for the present embodiment, on the left side). The automatic steering switching lever <NUM> and the forward-reverse switching lever <NUM> are present at respective positions different from each other in the front-back direction of the vehicle body. For the present embodiment, the automatic steering switching lever <NUM> is positioned forward of the forward-reverse switching lever <NUM>.

The steering tower <NUM> is provided with a forward-reverse switch <NUM> configured to switch the travel direction of the travel vehicle body <NUM> between a forward travel and a reverse travel in accordance with the operation position of the forward-reverse switching lever <NUM>. The forward-reverse switch <NUM> is capable of detecting the operation position of the forward-reverse switching lever <NUM>. The forward-reverse switch <NUM> is positioned under that portion of a gear case <NUM> which is present on the left side from the rotation axis Z1 of the steering wheel <NUM>. The forward-reverse switch <NUM> is supported by the steering post <NUM> via a stay <NUM>.

The forward-reverse switching lever <NUM> is switchable to any of (i) a forward-travel position for the travel vehicle body <NUM> to travel forward, (ii) a reverse-travel position for the travel vehicle body <NUM> to travel backward, and (iii) a neutral position for the travel vehicle body <NUM> to stop. The forward-reverse switching lever <NUM> extends upward from a height below the gear case <NUM> to a height between the upper end and the lower end of the steering wheel <NUM>. The forward-reverse switching lever <NUM> includes (i) a grip portion 20a for the driver to hold, (ii) a connection portion 20b connected with the forward-reverse switch <NUM>, and (iii) a rod portion 20c extending between the grip portion 20a and the connection portion 20b. The grip portion 20a is positioned at a height between the upper end and the lower end of the steering wheel <NUM>. The rod portion 20c extends upward from the connection portion 20b in such a pattern as to be apart from the gear case <NUM>.

The setting switches <NUM> are each for use to select a setting for automatic steering of the travel vehicle body <NUM>. The setting switches <NUM> include a correction switch <NUM>, a dial switch <NUM>, and a switch <NUM>. The correction switch <NUM>, the dial switch <NUM>, and the switch <NUM> are positioned at an upper portion of the steering tower <NUM> and below the steering wheel <NUM>. The correction switch <NUM>, the dial switch <NUM>, and the switch <NUM> are positioned on that side of the rotation axis Z1 of the steering wheel <NUM> on which the driver's seat <NUM> is present (that is, on the back side). The correction switch <NUM>, the dial switch <NUM>, and the switch <NUM> are arranged laterally in this order from the left side.

The tractor is configured to determine the position of the travel vehicle body <NUM> on the basis of (i) the position of the travel vehicle body <NUM> as determined by the GPS antenna unit <NUM> and (ii) the inertia information of the travel vehicle body <NUM> as measured by the inertia measuring device. The correction switch <NUM> is for use to correct the determined position of the travel vehicle body <NUM>. The correction switch <NUM> includes (i) a left correction switch portion 33a for correcting the determined position of the travel vehicle body <NUM> to the left side and (ii) a right correction switch portion 33b for correcting the determined position of the travel vehicle body <NUM> to the right side.

The dial switch <NUM> is capable of being pressed and rotated. Pressing the dial switch <NUM> causes, for example, any of various instructions to be entered. Long-pressing the dial switch <NUM> causes, for example, any of various menus to be invoked. Rotating the dial switch <NUM> clockwise or counter clockwise causes, for example, any of various items to be selected. The functions corresponding to the different operations of the dial switch <NUM> are, however, not limited to the above (that is, the entry, menu invocation, and selection).

The switch <NUM> is capable of being pressed. Pressing the switch <NUM> causes, for example, the previous screen to be displayed. Long-pressing the switch <NUM> causes, for example, the home screen to be displayed. The functions corresponding to the different operations of the switch <NUM> are, however, not limited to the above (that is, displaying the previous screen or home screen).

The switch <NUM> is for use to operate the headlights and turn signals. The switch <NUM> is positioned to the right side of the rotation axis Z1 of the steering wheel <NUM>.

As illustrated in <FIG>, the automatic steering mechanism <NUM> includes (i) a motor M configured to drive the steering shaft <NUM> to rotate, (ii) a gear mechanism G configured to transmit the driving force of the motor M to the steering shaft <NUM>, and (iii) a gear case <NUM> containing the gear mechanism G. The motor M and the gear case <NUM> are arranged vertically. Specifically, the motor M is positioned above the gear case <NUM>.

The gear mechanism G includes (i) an output gear <NUM> provided for the output shaft of the motor M, (ii) a first relay gear <NUM> meshing with the output gear <NUM>, (iii) a second relay gear <NUM> coaxial with the first relay gear <NUM> and configured to rotate together with the first relay gear <NUM>, and (iv) an input gear <NUM> provided on the steering shaft <NUM> and meshing with the second relay gear <NUM>. The gear case <NUM> is positioned under the steering wheel <NUM> and is present at such a position as to be shifted to the left side with respect to the rotation axis Z1 of the steering wheel <NUM>. The gear case <NUM> has a thickness T1 in the up-down direction which thickness T1 is equal to or substantially equal to the thickness T2 of the motor M in the up-down direction. The gear case <NUM> is structured to be divided into two vertically arranged halves, namely an upper case portion 31a and a lower case portion 31b. The gear case <NUM> is supported by the steering post <NUM> with the steering shaft <NUM> extending through the gear case <NUM> in the up-down direction. The upper case portion <NUM> a has an upper face portion to which a lower end portion of the upper insertion portion <NUM> is fixed (bolted). The lower case portion <NUM> b has a lower face portion to which an upper end portion of the lower insertion portion <NUM> is fixed (bolted).

The motor M is positioned under the steering wheel <NUM> and to the left of the steering shaft <NUM>. The motor M is supported by the gear case <NUM>. Specifically, the motor M is supported by (that is, placed on and supported by) a portion of the gear case <NUM> which portion is positioned to the left side of the rotation axis Z1 of the steering wheel <NUM>. The motor M is fixed (screwed) to the upper face portion of the upper case portion 31a.

Claim 1:
A work vehicle, comprising:
- a steering wheel (<NUM>) for steering a travel vehicle body (<NUM>) of the work vehicle;
- a steering shaft (<NUM>) connected with the steering wheel (<NUM>), extending downward from the steering wheel (<NUM>), and configured to be rotated with use of the steering wheel (<NUM>);
- a steering tower (<NUM>) for which the steering wheel (<NUM>) and the steering shaft (<NUM>) are provided; and
- an automatic steering mechanism (<NUM>) configured to automatically steer the travel vehicle body (<NUM>) so that the travel vehicle body (<NUM>) travels on a target travel path; and
a forward-reverse switching lever (<NUM>) for switching a travel direction of the vehicle body (<NUM>) between a forward travel and a reverse travel, wherein
- the automatic steering mechanism (<NUM>) includes a motor (M) configured to drive the steering shaft (<NUM>) to rotate,
- the automatic steering mechanism (<NUM>) is present in the steering tower (<NUM>), and
- the motor (M) is present under the steering wheel (<NUM>) and adjacent laterally to the steering shaft (<NUM>),
characterized in that
the work vehicle comprises an automatic steering switching lever (<NUM>) for switching between starting and ending automatic steering, wherein the automatic steering switching lever (<NUM>) and the forward-reverse switching lever (<NUM>) are positioned at an upper portion of the steering tower (<NUM>) and below the steering wheel (<NUM>), and are present on a first side in the left-right direction of the vehicle body with respect to a rotation axis (Z1) of the steering wheel (<NUM>), and are present at respective positions different from each other in a front-back direction of the vehicle body.