Patent Description:
Heretofore, as examples of working vehicles, there have been known, for example, a loader, an excavator, and a carrier dumper each of which includes a travel unit equipped with crawlers tracks or tires, a vehicle body provided on the travel unit, and a work unit provided at the vehicle body and configured to be hydraulically operated.

Each of the above-mentioned working vehicles has mounted thereon a hydraulic pump which produces hydraulic pressure, and a drive source which drives the hydraulic pump. For example, a configuration that an engine (for example, a diesel engine) is used as the drive source is in widespread use, and a fuel tank in which a fuel for the engine is reserved is mounted at a predetermined position of the vehicle body.

Here, in a working vehicle exemplified by, for example, a loader, an issue that a fuel suction portion becomes exposed due to the occurrence of a deviation of a fuel inside a fuel tank and, thus, what is called air entrainment occurs so that fuel supply is inadvertently stopped, may arise at the time of inclined work (at the time of work in a state in which the vehicle body is inclined) or at the time of occurrence of large swinging of the vehicle body. To address this issue, in a conventional fuel tank of the working vehicle illustrated by example in PTL <NUM> (<CIT>), a configuration that a weir portion for causing a fuel to stay, for example, at the time of inclined work is provided inside the fuel tank and which is capable of causing the fuel to stay inside the weir portion when the vehicle body is inclined toward the front or toward the rear, thus preventing the supply of the fuel from being stopped due to air entrainment, is implemented.

However, particularly in the case of a working vehicle, since, by its nature, inclined work with respect to all directions (<NUM>°) may occur, it is important to be able to prevent the fuel suction portion from becoming exposed in whatever direction the vehicle body is inclined. If it is tried to implement a weir portion compatible with all directions (<NUM>°) by using a configuration illustrated by example in PTL <NUM>, an issue that the structure of the inside of the fuel tank becomes extremely complex may arise.

On the other hand, since a fuel tank is often formed in a flattened shape, there is an issue that the rigidity of a portion large in area (particularly, a bottom surface portion) becomes low (weak) and deformation is likely to occur therein. To address this issue, in the case of a conventional fuel tank, a solution to this issue is achieved by a configuration that a large number of portions subjected to drawing (raised portions provided in an inward protruding manner) are formed particularly at the bottom surface portion to increase (strengthen) the rigidity and prevent deformation.

However, in the case of such a configuration, an issue that the volume of an internal fuel reservation space (i.e., a tank capacity) becomes decreased and the maximum reservation amount of fuel becomes small may occur.

In response to the above issues, one or more aspects of the present invention are directed to providing a fuel tank of a working vehicle, the fuel tank having a configuration including a weir portion and being capable of, while achieving a reduction in the arrangement region (volume region) of the weir portion, in whatever direction out of all directions (<NUM>°) the vehicle body is inclined when a remaining fuel is small, causing a predetermined amount of fuel to stay in an inner region of the weir portion to prevent the supply of the fuel from being stopped due to air entrainment and capable of increasing the rigidity of the fuel tank and preventing deformation thereof.

The present invention solves the above-mentioned issues by solution means such as that described in the following.

According to an aspect of the present invention, a fuel tank which is mounted at a vehicle body of a working vehicle and in an inner portion of which a fuel is reserved, includes an upper surface portion, a bottom surface portion, and a peripheral wall portion, and a weir portion vertically arranged at the bottom surface portion and causing the fuel in a predetermined amount to stay in a predetermined position of the inner portion when the vehicle body is inclined, wherein the peripheral wall portion includes a first wall and a second wall which is perpendicular to and continuous with one end side of the first wall, and wherein the weir portion includes a first barrier as which the first wall is also used (that is, the first barrier acts also as the first wall), a second barrier as which the second wall is also used (that is, the second barrier acts also as the second wall), a third barrier parallel to the first barrier and relatively long (that is, the third barrier is longer relative to the fourth barrier), a fourth barrier parallel to the first barrier, arranged between the first barrier and the third barrier, and relatively short (that is, the fourth barrier is shorter relative to the third barrier), and a fifth barrier interconnecting the third barrier and the fourth barrier. The third barrier, fourth barrier, and fifth barrier may be referred to as a third weir, fourth weir, and fifth weir, respectively, in that each acts as a barrier allowing some fluid (fuel) flow across the top (between the weir and the upper surface portion) depending on the fuel level. The amount of fluid flow may depend on the incline of the fuel tank and on the level of the fluid within the fuel tank, to allow fluid in a predetermined amount to be blocked in position by the weir when the tank is inclined at a certain angle.

Moreover, the third barrier, the fourth barrier, and the fifth barrier included in the weir portion may be formed continuous in a shape of letter J in plan view or a shape of left-right reversal (mirror) of letter J in plan view. That is, the third barrier, the fourth barrier, and the fifth barrier together may form a continuous letter J (hooked) shape in plan view.

Moreover, the fuel tank may further include a fixing band insertion hole formed at a region between the second wall and a fore-end portion of the fourth barrier and penetrating through the upper surface portion and the bottom surface portion in such a way as to communicate with an exterior of the fuel tank and not to communicate with an interior of the fuel tank.

Moreover, the bottom surface portion may include a fuel suction portion at an inner region surrounded by the third barrier, the fourth barrier, and the fifth barrier and may include a drain portion at an outer region other than the inner region, and a flow path opened toward the drain portion and causing the fuel staying inside the weir portion when the vehicle body is inclined to flow toward the drain portion when the vehicle body has become uninclined is provided between the fixing band insertion hole and the fore-end portion of the fourth barrier.

According to one or more aspects of the present invention, it is possible to, while achieving a reduction in the arrangement region (volume region) of the weir portion, in whatever direction out of all directions (<NUM>°) the vehicle body is inclined when a remaining fuel is small, cause a predetermined amount of fuel to stay in an inner region of the weir portion. Accordingly, it is possible to concurrently implement a configuration capable of increasing the volume of a fuel reservation space and a configuration that the supply of the fuel is prevented from being stopped due to air entrainment in whatever direction the vehicle body is inclined when a remaining fuel is small. In addition to this, it is possible to increase the rigidity of the fuel tank while achieving a reduction in portions subjected to drawing provided at the bottom surface portion.

Embodiments of the present invention are described below in detail with reference to the drawings. <FIG> is a schematic view (a perspective view as viewed from above a left front portion) illustrating an example of a working vehicle <NUM> at which a fuel tank <NUM> according to the present embodiment is mounted, and <FIG> is a perspective view with a part thereof shown in cross-section used to explain a mounting position for the fuel tank <NUM>. Furthermore, for the purpose of illustration, up and down, left and right, and front and rear directions may be represented by arrows in the figures. Moreover, in all of the figures for use in describing the embodiment, members having the same functions are assigned the respective same reference characters, and the repetitive description thereof may be omitted.

First, an overall configuration of the working vehicle <NUM> is described. While, here, a loader which travels with crawlers (called a "crawler loader") is described as an example, the present embodiment is not limited to this.

As illustrated in <FIG>, the working vehicle <NUM> is configured to include, with respect to a vehicle body <NUM> thereof, a travel unit <NUM> at a lower portion thereof, a work unit <NUM> at a front portion thereof, a cabin <NUM> at a central portion thereof, an engine compartment <NUM> in which, for example, an engine is contained, at a rear portion thereof, and arm posts <NUM>, to which arms <NUM> for causing the work unit <NUM> to operate are attached, at the rear portion thereof. Furthermore, the travel unit <NUM> is configured to include, for example, a pair of left and right crawlers (tracks) <NUM>. However, the present embodiment is not limited to this, and the travel unit <NUM> can be configured to travel with a pair of left and right tires (called a "skid-steer loader") (not illustrated).

First, the work unit <NUM> is configured to include a pair of left and right arms <NUM> which is pivotally connected to the arm posts <NUM> in such a way as to be swingable up and down, a bracket <NUM> which is pivotally connected to fore-end portions of the arms <NUM> in such a way as to be swingable up and down, and an attachment <NUM> (in the present embodiment, a bucket) which is attached to the bracket <NUM> in a detachable manner. Here, a pair of left and right arm cylinders <NUM> is provided in such a way as to span the arm posts <NUM> and the arms <NUM>, and a pair of left and right cylinders for attachment (commonly known as a "bucket cylinder") <NUM> is provided in such a way as to span the bracket <NUM> and the arms <NUM>.

According to this configuration, causing the arm cylinders <NUM> to extend and contract enables causing the arms <NUM> to swing up and down with respect to the vehicle body <NUM>. Moreover, causing the cylinders for attachment <NUM> to extend and contract enables causing the bracket <NUM>, i.e., the attachment <NUM> mounted thereon, to swing up and down with respect to the arms <NUM>.

In the present embodiment, a configuration that a bucket is provided as the attachment <NUM> is described as an example. However, the present embodiment is not limited to this configuration, and the attachment <NUM> is selected and mounted as appropriate in conformity with a work use. As another example of the attachment <NUM>, a hydraulically driven attachment such as a concrete cutter or a trencher can be mounted (not illustrated). The attachment <NUM> is configured to be replaceable alone or together with the bracket <NUM>. Alternatively, there is a configuration that a bracket and a bucket are integrated with each other (not illustrated). Furthermore, the working vehicle <NUM> is provided with an oil passage for supplying hydraulic oil to a hydraulically driven attachment (not illustrated).

Furthermore, the other mechanisms (for example, a drive mechanism and a control mechanism) for travel and work in the working vehicle <NUM> according to the present embodiment are similar to those in a known working vehicle (here, a track loader) and, therefore, the detailed description thereof is omitted.

Next, the engine compartment <NUM> is provided at the rear portion of the vehicle body <NUM> (at a position behind the cabin <NUM>), and is equipped with, in the form of being contained therein, for example, an engine (not illustrated) serving as a drive source and peripheral equipment therefor. For example, a diesel engine is used as the engine, but the present embodiment is not limited to this. The above-mentioned travel unit <NUM> and work unit <NUM> are configured to be driven by receiving pressure oil supplied from each hydraulic pump driven by the engine. Furthermore, a configuration that a battery is used together with the engine as the drive source can be employed (not illustrated).

On the other hand, as illustrated in <FIG>, the fuel tank <NUM>, in which a fuel (for example, light oil) to be supplied to the engine is reserved, is mounted at the front portion of the vehicle body <NUM> (at a position below the cabin <NUM>). Here, as an example of the fuel tank <NUM> according to the present embodiment, a perspective view of the appearance thereof, a perspective view of the inside thereof (a diagram as viewed from the front), and a perspective view of the inside thereof (a diagram as viewed from the rear) are illustrated in <FIG>, and <FIG>, respectively. For example, while the fuel tank <NUM> is configured to be formed from a resin material (for example, polyethylene), the present embodiment is not limited to this and the fuel tank <NUM> can be configured to be formed from, for example, a metallic material.

The fuel tank <NUM> is formed in the form of a hollow box including an upper surface portion <NUM>, a bottom surface portion <NUM>, and a peripheral wall portion <NUM> surrounding a space between the upper surface portion <NUM> and the bottom surface portion <NUM>. For example, the peripheral wall portion <NUM> includes a first wall <NUM> which is arranged at the front side, a second wall <NUM> which has a configuration perpendicular to and continuous with one end side (in this example, the right end) of the first wall <NUM> and is arranged at the right side, a third wall <NUM> which has a configuration perpendicular to and continuous with the other end side (in this example, the left end) of the first wall <NUM> and is arranged at the left side, and a fourth wall <NUM> which has a configuration continuous with the rear end of the second wall <NUM> and the rear end of the third wall <NUM> and is arranged at the rear side. Furthermore, the arrangement configuration regarding front, rear, left, and right can be reversed as appropriate. Moreover, while, for convenience of designing, the fourth wall <NUM> is provided with a recess for preventing interference to other equipment mounted in the working vehicle <NUM>, this configuration is not essential but can be omitted or altered as appropriate.

Moreover, the fuel tank <NUM> includes a weir portion <NUM> which is vertically arranged on the bottom surface portion <NUM> (the inner side) and is configured to cause a fuel in a predetermined amount to stay in a predetermined position (an inner region thereof) at the time of inclined work (i.e., when the vehicle body <NUM> is inclined). For example, as illustrated in <FIG> and <FIG>, the weir portion <NUM> includes a first barrier <NUM> to a fifth barrier <NUM>. Specifically, the first barrier <NUM> has a configuration as which the first wall <NUM> is also used. Moreover, the second barrier <NUM> has a configuration as which the second wall <NUM> is also used. Moreover, the third barrier <NUM> has a configuration parallel to the first barrier <NUM> (i.e., the first wall <NUM>) and formed relatively long and is arranged between the first wall <NUM> and the fourth wall <NUM> (in this example, on a side closer to the first wall <NUM> than the middle therebetween). Moreover, the fourth barrier <NUM> has a configuration parallel to the first barrier <NUM> (i.e., the first wall <NUM>) and formed relatively short and is arranged between the first barrier <NUM> and the third barrier <NUM>. Moreover, the fifth barrier <NUM> has a configuration continuous with one end side (in this example, the left end) of the third barrier <NUM> and one end side (in this example, the left end) of the fourth barrier <NUM>. Additionally, at the bottom surface portion <NUM>, the fuel tank <NUM> includes a fuel suction portion <NUM> in an inner region surrounded by the third barrier <NUM>, the fourth barrier <NUM>, and the fifth barrier <NUM>, and also includes a drain portion <NUM> in an outer region other than the inner region. Furthermore, a fuel tubing (not illustrated) which communicates with a fuel pump (not illustrated) is connected to the fuel suction portion <NUM>. On the other hand, a plug (not illustrated) is screwed to the drain portion <NUM>, and detaching the plug enables discharging a fuel or grounds to the outside.

According to this configuration, studying out a configuration that the first wall <NUM> and the second wall <NUM> are directly used as parts of the weir portion <NUM> enables achieving a reduction in the arrangement region (volume region) of the weir portion <NUM>. Moreover, implementing such a simple configuration enables, in whatever direction out of all directions (<NUM>°) the vehicle body <NUM> is inclined when a remaining fuel is small (in an amount smaller than or equal to a predetermined amount), causing a fuel in a predetermined amount to stay at a predetermined position (specifically, in an inner region of the weir portion <NUM> including the position of the fuel suction portion <NUM>).

Here, <FIG> illustrate states that a fuel has stayed in the inner region of the weir portion <NUM> when the vehicle body <NUM> is inclined. <FIG> is a sectional view illustrating a state obtained when the vehicle body <NUM> is inclined toward the front (a sectional view taken along line A-A in <FIG>), and <FIG> is a sectional view illustrating a state obtained when the vehicle body <NUM> is inclined toward the rear (a sectional view taken along line A-A in <FIG>). <FIG> is a sectional view illustrating a state obtained when the vehicle body <NUM> is inclined toward the right (a sectional view taken along line B-B in <FIG>), and <FIG> is a sectional view illustrating a state obtained when the vehicle body <NUM> is inclined toward the left (a sectional view taken along line B-B in <FIG>). As illustrated in figures for such typical four directions (front, rear, right, and left), in whatever direction the vehicle body <NUM> is inclined, an action that a fuel is caused to stay in the inner region of the weir portion <NUM> including the position of the fuel suction portion <NUM> is obtained.

As described above, it is possible to concurrently implement a configuration capable of further increasing an amount of reservable fuel (i.e., the maximum reservation amount in the fuel tank <NUM>) and a configuration that the supply of the fuel is prevented from being stopped due to air entrainment in whatever direction the vehicle body <NUM> is inclined when a remaining fuel is small. Furthermore, as compared with a conventional configuration (the case where the outside dimension is the same), a verification result that the amount of fuel staying inside the weir portion <NUM> in the same inclination angle increases has been obtained, so that an advantageous effect leading to prolongation of the operating time of the working vehicle <NUM> is synergistically obtained.

Here, with regard to a more specific shape of the weir portion <NUM>, the third barrier <NUM>, the fourth barrier <NUM>, and the fifth barrier <NUM>, excluding the first barrier <NUM> also used as the first wall <NUM> and the second barrier <NUM> also used as the second wall <NUM>, are formed continuous in the shape of letter J in plan view (or, in some cases, the shape of left-right reversal of letter J in plan view depending on, for example, a positional relationship between the second wall <NUM> and the third wall <NUM>) in which the start end (the right end of the third barrier <NUM>) is perpendicular to and continuous with the second wall <NUM>, and in the shape of updown reversal of letter U in the cross-section thereof (that is, a hollow shape which is convex upward). Furthermore, while the dimensions of the third barrier <NUM>, the fourth barrier <NUM>, and the fifth barrier <NUM> are not specifically limited, as an example of formation, the width dimension of each of the third barrier <NUM>, the fourth barrier <NUM>, and the fifth barrier <NUM> is about <NUM>, the length dimension (dimension in the longitudinal direction) of the third barrier <NUM> is about <NUM>, the length dimension (dimension in the longitudinal direction) of the fourth barrier <NUM> is about <NUM>, and the separation dimension between the third barrier <NUM> and the fourth barrier <NUM> is <NUM>. On the other hand, the height dimension of each of the third barrier <NUM>, the fourth barrier <NUM>, and the fifth barrier <NUM> is about <NUM>.

According to this configuration, the weir portion <NUM> enables obtaining not only an action of causing a fuel to stay at the time of inclination of the vehicle body <NUM> but also a reinforcement action of preventing the deformation of the fuel tank <NUM> (particularly, the bottom surface portion <NUM>). Accordingly, since it is possible to reduce the number of portions subjected to drawing (raised portions provided in an inward protruding manner), a large number of which have been provided for deformation prevention in a conventional fuel tank, it is possible to increase the amount of reservable fuel (i.e., the maximum reservation amount in the fuel tank <NUM>) without increasing the external form of the fuel tank <NUM>.

Moreover, the fuel tank <NUM> according to the present embodiment is configured to be fixed to the vehicle body <NUM> with use of two fixing bands <NUM> and <NUM> each made from a metallic material. Here, the fuel tank <NUM> is provided with a fixing band insertion hole <NUM>, into which one end of the fixing band <NUM> which is one of the two fixing bands <NUM> and <NUM>, is inserted. The fixing band insertion hole <NUM> is formed at a region between the second wall <NUM> and a fore-end portion 64a of the fourth barrier <NUM> in plan view and penetrating through the upper surface portion <NUM> and the bottom surface portion <NUM> in such a way as to communicate with an exterior (an outer region of the fuel tank <NUM>) and not to communicate with an interior (an inner region of the fuel tank <NUM>).

Here, an issue that a region corresponding to the opening position thereof (i.e., a region between the second wall <NUM> and the fore-end portion 64a of the fourth barrier <NUM> in plan view) is a region in which no constituent element of the weir portion <NUM> is arranged with regard to the third barrier <NUM>, the fourth barrier <NUM>, and the fifth barrier <NUM> continuous in the shape of letter J (or the shape of reversal of letter J), and is, therefore, relatively low in strength and easily deformable, arises. To address this issue, a configuration that the above-mentioned fixing band insertion hole <NUM> is arranged at this region is employed, so that the third barrier <NUM>, the fourth barrier <NUM>, the fifth barrier <NUM>, and the fixing band insertion hole <NUM> are able to be used to prevent portions reduced in strength from being unevenly distributed in the bottom surface portion <NUM> and, thus, it is possible to obtain a stronger reinforcing effect (deformation preventing effect).

Moreover, the fuel tank <NUM> is provided with, between the fixing band insertion hole <NUM> (specifically, a wall surface exposed on the inner side of the fuel tank <NUM>) and the fore-end portion 64a of the fourth barrier <NUM>, a flow path <NUM> opened toward the drain portion <NUM> and causing the fuel staying inside the weir portion <NUM> when the vehicle body <NUM> is inclined to flow toward the drain portion <NUM> when the vehicle body <NUM> has become uninclined.

Since, as mentioned above, with regard to the configuration of the weir portion <NUM>, particularly, the third barrier <NUM>, the fourth barrier <NUM>, and the fifth barrier <NUM> are formed in the shape of letter J (the shape of reversal of letter J), an action of causing a fuel to stay in an inner region of the weir portion <NUM> at the time of inclination of the vehicle body <NUM>. However, on the other hand, an issue that grounds become likely to stay in the surrounded inner region arises. To address this issue, the above-described configuration enables discharging grounds in the inner region toward the drain portion <NUM> by causing a fuel staying in the weir portion <NUM> at the time of inclination of the vehicle body <NUM> to flow through the flow path <NUM> when the vehicle body <NUM> has become uninclined (after that, opening the drain portion <NUM> enables discharging the grounds to the outside of the fuel tank <NUM>).

As described above, according to a fuel tank of the present invention, it is possible to, while achieving a reduction in the arrangement region (volume region) of a weir portion, cause a fuel in a predetermined amount to stay inside the weir portion in whatever direction out of all directions (<NUM>°) the vehicle body is inclined. Accordingly, it is possible to concurrently implement a configuration capable of increasing the volume of a fuel reservation space (i.e., the maximum reservation amount of fuel) and a configuration that the supply of the fuel is prevented from being stopped due to air entrainment in whatever direction the vehicle body is inclined when a remaining fuel is small. In addition to this, it is possible to increase the rigidity of the fuel tank while achieving a reduction in portions subjected to drawing provided at the bottom surface portion.

Claim 1:
A fuel tank (<NUM>) for mounting at a vehicle body (<NUM>) of a working vehicle (<NUM>) and in an inner portion of which a fuel may be reserved, the fuel tank (<NUM>) of the working vehicle (<NUM>) comprising:
an upper surface portion (<NUM>), a bottom surface portion (<NUM>), and a peripheral wall portion (<NUM>); and
a weir portion (<NUM>) vertically arranged at the bottom surface portion (<NUM>) and causing the fuel in a predetermined amount to stay in a predetermined position of the inner portion when the vehicle body (<NUM>) is inclined,
wherein the peripheral wall portion (<NUM>) includes a first wall (<NUM>) and a second wall (<NUM>) which is perpendicular to and continuous with one end side of the first wall (<NUM>), characterized in that
the weir portion (<NUM>) includes a first barrier (<NUM>) as which the first wall (<NUM>) is also used, a second barrier (<NUM>) as which the second wall (<NUM>) is also used, a third barrier (<NUM>) parallel to the first barrier (<NUM>) and relatively long, a fourth barrier (<NUM>) parallel to the first barrier (<NUM>), arranged between the first barrier (<NUM>) and the third barrier (<NUM>), and relatively short, and a fifth barrier (<NUM>) interconnecting the third barrier (<NUM>) and the fourth barrier (<NUM>).