Patent Description:
<CIT> discloses an example of an electric work vehicle. <CIT> states that a transmission case that houses a transmission for travel is provided at a rear portion of the work vehicle, and a motor is joined to a front portion of the transmission case. Motive power from the motor is transmitted to the transmission, and is then transmitted from the transmission to front wheels (each of which corresponds to a travel device) and rear wheels (each of which corresponds to a travel device). Documents <CIT>, <CIT> and <CIT> each disclose examples of known work vehicles.

<CIT> discloses an example of related art.

In <CIT>, the motor, which is a heavy object, is located at the center of the work vehicle in the front-back direction, and the motor hardly affects the front-back balance of the work vehicle.

However, the weight of the work device is likely to change the front-back balance of the work vehicle since the work vehicle performs work travel with the work device supported by a front portion of the work vehicle or with the work device supported by a rear portion of the work vehicle.

The present invention aims to configure a work vehicle such that a motor, which is a heavy object, being provided at an appropriate position improves the front-back balance of the work vehicle with the work device supported by the work vehicle.

A work vehicle of the present invention includes: at least one travel device including a front travel device; a battery; a motor; an inverter configured to operate the motor; an operation section including an operator seat; a transmission case housing a transmission for travel; and a transmission shaft, wherein the motor is forward of the front travel device in a side view, and the motor, the transmission shaft, the transmission, and the travel device are connected to each other such that motive power from the motor is transmitted to the transmission via the transmission shaft and transmitted from the transmission to the travel device.

According to the present invention, the motor is relatively far forward from the center of the work vehicle in the front-back direction. This makes it easier for the motor to function as a balance weight with a work device having a relatively large weight supported by a rear portion of the work vehicle. This enables a work vehicle suitable for work travel with a work device having a relatively large weight supported by the rear portion of the work vehicle.

According to the present invention, outside air is more likely to hit the motor while the work vehicle moves forward, which is advantageous in terms of cooling the motor.

In the present invention, it is preferable that the work vehicle further includes: a work device; a link mechanism disposed on the transmission case, configured to be raised and lowered, and joined to the work device; a hydraulic cylinder disposed on the transmission case and configured to raise and lower the link mechanism; a hydraulic pump configured to supply hydraulic oil to the hydraulic cylinder; and a pump motor configured to drive the hydraulic pump, wherein the transmission case is below the operator seat, and the pump motor is between the operator seat and the transmission case in a side view.

In the present invention, it is preferable that the work vehicle further includes: a work device; a link mechanism disposed on the transmission case, configured to be raised and lowered, and joined to the work device; and a work motor configured to supply motive power to the work device, wherein the work motor is in the link mechanism.

<FIG> show electric tractors, each of which is an example of a work vehicle. In <FIG>, F indicates the forward direction, B indicates the rearward direction, U indicates the upward direction, D indicates the downward direction, R indicates the rightward direction, and L indicates the leftward direction.

As shown in <FIG>, left and right front wheels <NUM> (each of which corresponds to a front travel device) and left and right rear wheels <NUM> (each of which corresponds to a rear travel device) support a body <NUM> of the tractor. A hood <NUM> is provided at a front portion of the body <NUM>, and an operation section <NUM> is provided at a rear portion of the body <NUM>. The operation section <NUM> includes a steering wheel <NUM> for steering the front wheels <NUM>, an operator seat <NUM>, a floor <NUM>, and a ROPS frame <NUM>.

The body <NUM> has left and right body frames <NUM>, a transmission case <NUM>, and so on. The transmission case <NUM> has a front case <NUM> and a rear case <NUM> that are joined to each other. The left and right body frames <NUM> are connected to the transmission case <NUM> and extend in the front-back direction below the operation section <NUM> (floor <NUM>). The transmission case <NUM> is located below the operator seat <NUM> in the operation section <NUM>.

A front axle case <NUM> is supported by front portions of the body frames <NUM>, and supports the left and right front wheels <NUM>. The transmission case <NUM> (rear case <NUM>) supports the left and right rear wheels <NUM>.

A top link <NUM> (which corresponds to a link mechanism) and left and right lower links <NUM> (each of which corresponds to a link mechanism) are provided at a rear portion of the transmission case <NUM> (rear case <NUM>) in such a manner as to be swingable in the up-down direction. The top link <NUM> and the lower links <NUM> can be joined to a work device (not shown), such as a rotary cultivator.

Left and right lift arms <NUM> are provided at the rear portion of the transmission case <NUM> (rear case <NUM>), and a connecting rod <NUM> is connected to the lift arms <NUM> and the lower links <NUM>. The top link <NUM> and the lower links <NUM> are raised and lowered and the work device is raised and lowered by swinging the lift arms <NUM> in the up-down direction.

As shown in <FIG> and <FIG>, a pillar frame <NUM> is provided on the body frames <NUM> between the front wheels <NUM> and the operation section <NUM> (rear wheels <NUM>). The pillar frame <NUM> is constituted by a folded plate material and has a right section 19a, a left section 19b, an upper section 19c, and a rear section 19d.

The rear section 19d of the pillar frame <NUM> is flat and extends in the up-down direction and the left-right direction. The right section 19a of the pillar frame <NUM> is formed by bending forward a right portion of the rear section 19d of the pillar frame <NUM>, and extends in the up-down direction and the front-back direction. The left section 19b of the pillar frame <NUM> is formed by bending forward a left portion of the rear section 19d of the pillar frame <NUM>, and extends in the up-down direction and the front-back direction.

The upper section 19c of the pillar frame <NUM> is formed by bending forward an upper portion of the rear section 19d of the pillar frame <NUM>, and extends in the left-right direction and the front-back direction. The upper section 19c of the pillar frame <NUM> extends between upper portions of the right section 19a and the left section 19b of the pillar frame <NUM>.

As shown in <FIG>, the hood <NUM> is supported such that the hood <NUM> is openable and closable about a fulcrum in the left-right direction of the upper section 19c of the pillar frame <NUM>, and can be operated from a closed position shown in <FIG> to an open position above the closed position.

A power steering mechanism <NUM> is provided below a rear face portion of the rear section 19d of the pillar frame <NUM>. A steering post <NUM> is attached to the power steering mechanism <NUM> and extends upward from the power steering mechanism <NUM>. A steering wheel <NUM> is supported by an upper portion of the steering post <NUM>, and a steering shaft <NUM> is connected to the steering wheel <NUM> and the power steering mechanism <NUM>.

In response to the steering wheel <NUM> being rotated, the rotation of the steering wheel <NUM> is transmitted to the power steering mechanism <NUM> via the steering shaft <NUM>, and the power steering mechanism <NUM> steers the front wheels <NUM> to the left and right.

With the above configuration, the steering wheel <NUM> for operating the front wheels <NUM> (front travel devices) is provided at a front portion of the operation section <NUM>, and the steering shaft <NUM> for operating the front wheels <NUM> (front travel devices) extends downward from the steering wheel <NUM>, as shown in <FIG>.

A support platform <NUM> is attached to front upper portions of the left and right body frames <NUM>, as shown in <FIG> and <FIG>. An inverter <NUM>, which is provided on the support platform <NUM>, has a rectangular case with a small dimension (dimension in the front-back direction) that houses various types of equipment.

The inverter <NUM> extends in the up-down direction in a side view and extends in the left-right direction in a plan view (front view), and is attached to a rear portion of the support platform <NUM> so as to be in contact with a front face portion of the rear section 19d of the pillar frame <NUM>.

As shown in <FIG>, the tractor has a battery <NUM>, which is constituted by multiple pairs of stacks (not shown) of connected battery modules (not shown) that are housed in a rectangular-parallelepiped case. The battery <NUM> is attached to the support platform <NUM>, and the hood <NUM> at the closed position covers the inverter <NUM> and the battery <NUM>. Maintenance work for the inverter <NUM> and the battery <NUM> can be performed by opening the hood <NUM>.

With the above configuration, the inverter <NUM> is provided between the right section 19a and the left section 19b of the pillar frame <NUM> in a front view and overlaps the right section 19a and the left section 19b of the pillar frame <NUM> in a side view, as shown in <FIG> and <FIG>. The inverter <NUM> is provided below the upper section 19c of the pillar frame <NUM> in a front view and overlaps the upper section 19c of the pillar frame <NUM> in a plan view.

The battery <NUM> is provided forward of the operation section <NUM>, and the inverter <NUM> is provided between the battery <NUM> and the operation section <NUM> in a side view. The inverter <NUM> is provided between the battery <NUM> and the steering shaft <NUM> in a side view.

The pillar frame <NUM> is provided between the battery <NUM> and the operation section <NUM> in a side view, and the inverter <NUM> is provided between the battery <NUM> and the rear section 19d of the pillar frame <NUM> in a side view.

Left and right mounting brackets <NUM> are joined to inner faces of the left and right body frames <NUM>, and left and right portions of a motor <NUM> are joined to the left and right mounting brackets <NUM>, as shown in <FIG> and <FIG>.

The inverter <NUM> converts DC power from the battery <NUM> to AC power and supplies the AC power to the motor <NUM> to operate the motor <NUM>. Motive power from the motor <NUM> is supplied to the front wheels <NUM> and the rear wheels <NUM>, as shown in <FIG>.

With the above configuration, the motor <NUM> is provided between the front wheels <NUM> (front travel devices) and the rear wheels <NUM> (rear travel devices) and below the steering wheel <NUM> in a side view, as shown in <FIG> and <FIG>.

The left body frame <NUM> and the right body frame <NUM> are disposed in the front-back direction below the operation section <NUM> (floor <NUM>), and the motor <NUM> is provided between the left body frame <NUM> and the right body frame <NUM> in a plan view (front view).

The motor <NUM> is provided below the pillar frame <NUM>, the power steering mechanism <NUM>, the inverter <NUM>, and the rear portion of the battery <NUM> in a side view. The pillar frame <NUM>, the power steering mechanism <NUM>, and the inverter <NUM> are provided above the motor <NUM> in a side view.

A hydrostatic continuously variable transmission <NUM> (which corresponds to a transmission for travel) is housed within the front case <NUM> of the transmission case <NUM>, and motive power from the motor <NUM> is transmitted via a transmission shaft <NUM> to the continuously variable transmission <NUM>, as shown in <FIG> and <FIG>. The continuously variable transmission <NUM> is capable of steplessly changing forward and backward and is operated by a gearshift pedal (not shown) on the floor <NUM> of the operation section <NUM>.

An auxiliary transmission <NUM> (which corresponds to a transmission for travel), a rear wheel differential device <NUM>, and a front wheel transmission <NUM> (which corresponds to a transmission for travel) are housed within the rear case <NUM> of the transmission case <NUM>. Motive power subjected to speed change by the continuously variable transmission <NUM> is transmitted to the auxiliary transmission <NUM>, and is then transmitted from the auxiliary transmission <NUM> to the rear wheels <NUM> via the rear wheel differential device <NUM>.

Motive power diverted from between the auxiliary transmission <NUM> and the rear wheel differential device <NUM> is transmitted to the front wheel transmission <NUM>, then transmitted from the front wheel transmission <NUM> via the transmission shaft <NUM> to the front wheel differential device <NUM> housed within the front axle case <NUM>, and is transmitted from the front wheel differential device <NUM> to the front wheels <NUM>.

The front wheel transmission <NUM> drives the front wheels <NUM> and the rear wheels <NUM> at the same speed while the front wheels <NUM> are operated within the range of left and right set angles from a straight-ahead position. The front wheel transmission <NUM> drives the front wheels <NUM> at a higher speed than the rear wheels <NUM> while the front wheels <NUM> are steered leftward or rightward beyond the left and right setting angles.

With the above configuration, the tractor has the transmission case <NUM> (front case <NUM> and rear case <NUM>) that houses the continuously variable transmission <NUM> (transmission for travel), the auxiliary transmission <NUM> (transmission for travel), and the front wheel transmission <NUM> (transmission for travel), as shown in <FIG>.

Motive power from the motor <NUM> is transmitted via the transmission shaft <NUM> to the continuously variable transmission <NUM> (transmission for travel), the auxiliary transmission <NUM> (transmission for travel), and the front wheel transmission <NUM> (transmission for travel), and is then transmitted from the continuously variable transmission <NUM> (transmission for travel), the auxiliary transmission <NUM> (transmission for travel), and the front wheel transmission <NUM> (transmission for travel) to the front wheels <NUM>(travel devices) and the rear wheels <NUM> (travel devices).

A PTO transmission <NUM> is housed within the rear case <NUM> of the transmission case <NUM>, and a PTO shaft <NUM> is provided at a rear portion of the rear case <NUM> of the transmission case <NUM>, as shown in <FIG> and <FIG>. A transmission shaft (not shown) is connected to the PTO shaft <NUM> and the work device in response to the work device being joined to the top link <NUM> and the lower links <NUM>.

While motive power from the motor <NUM> is transmitted to the continuously variable transmission <NUM> via the transmission shaft <NUM>, motive power from the transmission shaft <NUM> (motive power that is not subjected to speed change by the continuously variable transmission <NUM>) is transmitted to the PTO transmission <NUM>, and motive power subjected to speed change by the PTO transmission <NUM> is transmitted to the PTO shaft <NUM> and then transmitted from the PTO shaft <NUM> to the work device.

A single-acting hydraulic cylinder <NUM> is provided above the rear portion of the transmission case <NUM> (rear case <NUM>), and the hydraulic cylinder <NUM> raises and lowers the lift arm <NUM>, as shown in <FIG>.

A hydraulic pump <NUM> and a control valve <NUM> are provided within the rear portion of the transmission case <NUM> (rear case <NUM>). Lubricating oil that serves as hydraulic oil and stored in the transmission case <NUM> (rear case <NUM>) is supplied to the hydraulic pump <NUM>, and is then supplied from the hydraulic pump <NUM> to the control valve <NUM>.

A pump motor <NUM> is provided above the rear portion of the transmission case <NUM> (rear case <NUM>) and drives the hydraulic pump <NUM>. The inverter <NUM> converts DC power from the battery <NUM> to AC power and supplies the AC power to the pump motor <NUM> to operate the pump motor <NUM>.

Operations to supply and discharge the hydraulic oil to and from the hydraulic cylinder <NUM> are performed from the control valve <NUM>, and the hydraulic cylinder <NUM> raises and lowers the lift arm <NUM>. The hydraulic oil discharged from the hydraulic cylinder <NUM> is returned from control valve <NUM> to the transmission case <NUM> (rear case <NUM>).

With the above configuration, the hydraulic cylinder <NUM>, which raises and lowers the top link <NUM> (link mechanism) and the lower links <NUM> (link mechanism) to which the work device is joined, and the hydraulic pump <NUM>, which supplies the hydraulic oil to the hydraulic cylinder <NUM>, are provided in the transmission case <NUM> (rear case <NUM>), as shown in <FIG> and <FIG>.

The pump motor <NUM>, which drives the hydraulic pump <NUM>, is located between the operator seat <NUM> in the operation section <NUM> and the transmission case <NUM> (rear case <NUM>) in a side view.

In the configuration shown in <FIG> and <FIG>, the motor <NUM> may be joined to the support platform <NUM> and supported by the body <NUM>. The motor <NUM> may be joined to the pillar frame <NUM> and supported by the body <NUM>.

In the configuration shown in <FIG> and <FIG>, the inverter <NUM> may be joined to the pillar frame <NUM> and supported by the body <NUM>. The inverter <NUM> may be provided between the operator seat <NUM> in the operation section <NUM> and the transmission case <NUM> (front case <NUM> and rear case <NUM>) in a side view, as shown in <FIG>, which will be described later.

If the battery <NUM> is provided forward of the operation section <NUM> as shown in <FIG>, the inverter <NUM> may be provided forward of the battery <NUM>.

According to the configuration shown in <FIG>, the inverter <NUM> extends in the up-down direction in a side view and extends in the left-right direction in a plan view (front view), and is provided between a front portion of the hood <NUM> and a front portion of the battery <NUM>.

The motor <NUM> may be provided above the front axle case <NUM> (front wheels <NUM> (front travel devices)) in a side view, as shown in <FIG>.

According to the configuration shown in <FIG>, the motor <NUM> is provided below the front portion of the battery <NUM>, and the position of the motor <NUM> is slightly higher. Thus, another support platform <NUM> need only be provided to the support platform <NUM> such that the battery <NUM> is attached to the support platform <NUM> to make the position of the battery <NUM> slightly higher.

In the configuration shown in <FIG>, the motor <NUM> may be joined to the support platform <NUM> and supported by the body <NUM>. The inverter <NUM> may be provided forward of the battery <NUM>, as shown in <FIG>. The inverter <NUM> may be provided between the operator seat <NUM> in the operation section <NUM> and the transmission case <NUM> (front case <NUM> and rear case <NUM>) in a side view, as shown in <FIG>, which will be described later.

The motor <NUM> may be provided forward of the front axle case <NUM> (front wheels <NUM> (front travel devices)) in a side view, as shown in <FIG>.

According to the configuration shown in <FIG>, the motor <NUM> is located at a lower position. Thus, a transmission mechanism <NUM> of a gear transmission type need only be attached to a portion of an output shaft (not shown) of the motor <NUM> in such a manner as to extend upward from the motor <NUM>. The transmission shaft <NUM> need only be connected to an output shaft (not shown) at an upper portion of the transmission mechanism <NUM> and the continuously variable transmission <NUM> (see <FIG>) such that the transmission shaft <NUM> extends in the front-back direction above the front axle case <NUM>.

Motive power from the output shaft of the motor <NUM> is transmitted to the transmission mechanism <NUM>, then transmitted the output shaft at the upper portion of transmission mechanism <NUM> to the continuously variable transmission <NUM> (see <FIG>) via the transmission shaft <NUM>, and is transmitted to the front wheels <NUM> and the rear wheels <NUM>.

As shown in <FIG>, if the transmission case <NUM> (front case <NUM> and rear case <NUM>) is provided below the operator seat <NUM> in the operation section <NUM>, the motor <NUM> may be attached to the upper portion of the transmission case <NUM> (front case <NUM> and rear case <NUM>) and provided between the operator seat <NUM> in the operation section <NUM> and the transmission case <NUM> (front case <NUM> and rear case <NUM>) in a side view.

The inverter <NUM> may be provided between the operator seat <NUM> in the operation section <NUM> and the transmission case <NUM> (front case <NUM> and rear case <NUM>) in a side view by attaching the inverter <NUM> to a support frame <NUM> that is provided in the operation section <NUM> to support the operator seat <NUM>.

In the configuration shown in <FIG>, the motor <NUM> need only be attached to the upper portion of the transmission case <NUM> (front case <NUM> and rear case <NUM>) such that an output shaft (not shown) of the motor <NUM> faces forward, and a transmission mechanism <NUM> of a gear transmission type need only be attached to the output shaft of the motor <NUM> and a forward-facing input shaft (not shown) of the continuously variable transmission <NUM> (see <FIG>).

Motive power from the output shaft of the motor <NUM> is transmitted to the transmission mechanism <NUM>, then transmitted from an output shaft (not shown) at a lower portion of the transmission mechanism <NUM> to the continuously variable transmission <NUM> (see <FIG>), and is transmitted to the front wheels <NUM> and the rear wheels <NUM>.

In the configuration shown in <FIG>, the inverter <NUM> is supported in a suspended manner by a lower portion of the support frame <NUM> and extends in the horizontal direction. The inverter <NUM> is disposed at a position upward of and away from the motor <NUM> and the pump motor <NUM>, and is disposed at a position upward of and away from the upper portion of the transmission case <NUM> (front case <NUM> and rear case <NUM>).

If the motor <NUM> is provided between the operator seat <NUM> in the operation section <NUM> and the transmission case <NUM> (front case <NUM> and rear case <NUM>) in a side view, as shown in <FIG>, the inverter <NUM> may be provided rearward of the battery <NUM>, as shown in <FIG>. The inverter <NUM> may be provided forward of the battery <NUM>, as shown in <FIG>.

A work motor <NUM> may be provided on the left and right lower links <NUM> (link mechanism), as shown in <FIG>.

According to the configuration shown in <FIG>, with the work device joined to the top link <NUM> and the lower links <NUM>, a transmission shaft (not shown) is connected to the work motor <NUM> and the work device. The inverter <NUM> converts DC power from the battery <NUM> to AC power, which is supplied to the work motor <NUM> to operate the work motor <NUM>, and motive power from the work motor <NUM> is transmitted to the work device.

In the configuration shown in <FIG>, the PTO transmission <NUM> and the PTO shaft <NUM> shown in <FIG> and <FIG> may be eliminated. The work motor <NUM> may be provided on the top link <NUM> (link mechanism).

The tractor may have a four-wheel steering structure in which the front wheels <NUM> and the rear wheels <NUM> are steered in the same and opposite phases by the steering wheel <NUM>.

Crawler-type travel devices (not shown) may be provided instead of the front wheels <NUM> as the front travel devices. Crawler-type travel devices (not shown) may be provided instead of the rear wheels <NUM> as the rear travel devices. One crawler-type travel device (not shown) may be provided instead of the front wheels <NUM> and the rear wheels <NUM>.

Claim 1:
A work vehicle comprising:
at least one travel device (<NUM>, <NUM>) including a front travel device (<NUM>);
a battery (<NUM>);
a motor (<NUM>);
an inverter (<NUM>) configured to operate the motor (<NUM>);
an operation section (<NUM>) including an operator seat (<NUM>);
a transmission case (<NUM>) housing a transmission (<NUM>) for travel; and
a transmission shaft (<NUM>),
wherein the motor (<NUM>), the transmission shaft (<NUM>), the transmission (<NUM>), and the travel device (<NUM>, <NUM>) are connected to each other such that motive power from the motor (<NUM>) is transmitted to the transmission via the transmission shaft (<NUM>) and transmitted from the transmission (<NUM>) to the travel device (<NUM>, <NUM>), characterized in that the motor (<NUM>) is forward of the front travel device (<NUM>) in a side view.