Patent Description:
Conventionally, a work vehicle is known that is provided with a vehicle body frame that supports an engine, a cover frame coupled to the vehicle body frame so as to allow opening and closing, and an engine cover that is attached to the cover frame and covers the engine. The cover frame and the engine cover constitute an engine hood.

In the work vehicle described in <CIT>, one extendable member coupled to the vehicle body frame and the engine hood is provided for the purpose of easily opening and closing the engine hood. The extendable member is coupled to either one of the left side and the right side of the engine hood.

<CIT> discloses a skid steer loader that comprises a body frame and an engine cover assembly attached thereto. The engine cover assembly comprises an engine cover panel and a tailgate. The cover panel is attached to the tailgate and includes reinforcing ribs attached to one end of a planar section of the cover panel. The planar section of the cover panel is coupled to a gas spring which is also attached to the tailgate instead of the vehicle body frame.

<CIT> discloses a hydraulic excavator with an upper opening to an engine compartment covered by an engine hood. The engine hood is provided with gas springs attached directly to the engine hood and the vehicle body frame.

<CIT> discloses a tractor with an engine hood also provided with gas springs between the engine hood and the vehicle body frame.

<CIT> discloses a wheel loader with an engine hood that can be opened by use of an electric motor.

However, in the work vehicle described in <CIT>, the engine hood is cantilevered because the engine hood is supported only one side by the extendable member. As a result, shaking or deformation of the engine hood may easily occur while the engine hood is open or while opening and closing the engine hood. As a result, there is a concern that the engine hood may come into contact with peripheral members.

An object of the present invention is to provide a work vehicle with which shaking or deformation of the engine hood is suppressed.

A work vehicle is provided with a vehicle body frame, and engine hood, a first extendable member, and a second extendable member. The vehicle body frame supports an engine. The engine hood has a cover frame constituting a skeleton of the engine hood, wherein the cover frame is coupled to the vehicle body frame so as to allow opening and closing, and an engine cover that is attached to the cover frame and covers the engine. The first extendable member is coupled to the vehicle body frame and the cover frame and is disposed at one end side based on the center in the vehicle width direction of the work vehicle. The second extendable member is coupled to the vehicle body frame and the cover frame and is disposed at the other end side based on the center in the vehicle width direction of the work vehicle. Further, the one extendable member among the first extendable member and the second extendable member is an electric cylinder and the other extendable member among the first extendable member and the second extendable member is a gas damper.

According to a preferred embodiment, the gas damper biases the cover frame when the cover frame is in an open state.

In a further preferred embodiment, the vehicle body frame has a rear frame and a front frame disposed in front of the rear frame, and the cover frame, the first extendable member and the second extendable member are each coupled to the rear frame.

According to the present invention, there is provided a work vehicle with which shaking or deformation of the engine hood is suppressed.

A wheel loader <NUM> according to an embodiment of the present invention will be explained below with reference to the drawings. The wheel loader <NUM> is an example of a "work vehicle" according to the present invention.

In the following explanations, "up," "down," "front," "rear," "left," and "right" indicate directions relative to a state of looking forward from the driver's seat. The "up-down direction" signifies the vertical direction. The "front-back direction" signifies the front-back direction of the vehicle. The "vehicle width direction" signifies the left-right direction of the vehicle.

<FIG> is a side view seen from the right side of the wheel loader <NUM> according to the embodiment.

The wheel loader <NUM> is provided with a vehicle body frame <NUM>, a work implement <NUM>, a plurality of traveling wheels <NUM>, a cab <NUM>, an engine hood <NUM>, a pair of left and right steps <NUM> (only the step <NUM> on the right side is depicted in <FIG>), and a pair of left and right fenders <NUM> (only the fender <NUM> on the right side is depicted in <FIG>).

The vehicle body frame <NUM> is an articulated type and includes a front frame <NUM> and a rear frame <NUM>. The front frame <NUM> is disposed in front of the rear frame <NUM>. An engine <NUM> is mounted to the rear frame <NUM>.

The work implement <NUM> is mounted to a front part of the front frame <NUM>. The work implement <NUM> includes a boom <NUM> and a bucket <NUM>. The boom <NUM> is rotatably attached to the front frame <NUM>. The bucket <NUM> is rotatably attached to the tip of the boom <NUM>.

A pair of the traveling wheels <NUM> are attached to the left and right of the front frame <NUM>. A pair of the traveling wheels <NUM> are attached to the left and right of the rear frame <NUM>.

The cab <NUM> is disposed on the rear frame <NUM>. The operator's seat, various operating members, and a display device, etc. are disposed inside the cab <NUM>.

The engine hood <NUM> is coupled to the rear frame <NUM>. The engine hood <NUM> covers an engine room in which the engine <NUM> is installed. As illustrated in <FIG>, the engine hood <NUM> has an engine cover <NUM>, an intake pipe <NUM>, and an exhaust pipe <NUM>.

The engine cover <NUM> covers the engine <NUM>. While the constituent material of the engine cover <NUM> is not limited, a resin material, for example, can be used. The engine cover <NUM> according to the present embodiment extends in the front-back direction as seen from the side. The length of the engine cover <NUM> in the front-back direction is greater than the height in the up-down direction.

The intake pipe <NUM> is a member for taking in air to be supplied to the engine <NUM>. The intake pipe <NUM> protrudes upward from the engine cover <NUM>. The intake pipe <NUM> is disposed in front of the exhaust pipe <NUM>.

The exhaust pipe <NUM> is a member for releasing exhaust gas from the engine <NUM>. The exhaust pipe <NUM> protrudes upward from the engine cover <NUM>. The exhaust pipe <NUM> is disposed behind the intake pipe <NUM>.

An internal structure of the engine hood <NUM> is explained below.

The steps <NUM> are disposed above the traveling wheels <NUM> attached to the rear frame <NUM>. The steps <NUM> may be used for inspection work performed by a worker.

The fenders <NUM> are disposed above and to the rear of the traveling wheels <NUM> attached to the rear frame <NUM>. The fenders <NUM> are disposed so as to extend to the rear from the rear end of the steps <NUM>. The fenders <NUM> are attached to the engine cover <NUM>.

<FIG> is a side view illustrating, from the right side, the engine hood <NUM> to which the engine cover <NUM> is attached. <FIG> and <FIG> are perspective views illustrating, from the right side, the engine hood <NUM> to which the engine cover <NUM> is attached. A state in which the engine hood <NUM> is closed is depicted in <FIG> and <FIG>, and a state in which the engine hood <NUM> is open is depicted in <FIG>.

As illustrated in <FIG>, the engine hood <NUM> has a cover frame <NUM>, an electric cylinder <NUM> (an example of a first extendable member), and a gas damper <NUM> (example of a second extendable member).

The engine cover <NUM> (see <FIG>) is attached to the cover frame <NUM>. The cover frame <NUM> is disposed on the rear frame <NUM>. The rear frame <NUM> has a left beam 10a, a right beam 10b, and a rear beam 10c. The left beam 10a extends from a left end part of the rear beam 10c toward the front. The right beam 10b extends from a right end part of the rear beam 10c toward the front. The rear beam 10c is connected to the respective rear end parts of the left beam 10a and the right beam 10b. The rear beam 10c extends in the vehicle width direction.

The cover frame <NUM> is coupled to the rear frame <NUM> so as to allow opening and closing. As illustrated in <FIG>, the cover frame <NUM> is able to rotate respectively about a left shaft 20a and a right shaft 20b.

The left shaft 20a is a shaft member that extends in the vehicle width direction. Both ends of the left shaft 20a are fixed to a left shaft support part 10d provided to the left end part of the rear beam 10c of the rear frame <NUM>. A lower end part of a rear frame left part 21a is inserted into the left shaft support part 10d, and the left shaft 20a passes through the lower end part of the rear frame left part 21a.

The right shaft 20b is a shaft member that extends in the vehicle width direction. Both ends of the right shaft 20b are fixed to a right shaft support part 10e provided to the right end part of the rear beam 10c of the rear frame <NUM>. A lower end part of a rear frame right part 21b is inserted into the right shaft support part 10e, and the right shaft 20b passes through the lower end part of the rear frame right part 21b.

As illustrated in <FIG>, the cover frame <NUM> rotates around the left shaft 20a and the right shaft 20b whereby the front end part of the cover frame <NUM> rises upward and to the rear.

The cover frame <NUM> has a rear frame <NUM>, a left upper frame <NUM>, a left lower frame <NUM>, a first left upright frame 24a, a second left upright frame 24b, a right upper frame <NUM>, a right lower frame <NUM>, a first right upright frame 27a, a second right upright frame 27b, an upper frame <NUM>, and a shield plate <NUM>.

The rear frame <NUM> is disposed on the rear beam 10c of the rear frame <NUM>. The rear frame <NUM> is formed overall as a U-shape. The rear frame <NUM> includes the rear frame left part 21a, the rear frame right part 21b, and a rear frame upper part 21c. The rear frame left part 21a is disposed on the left end part of the rear beam 10c of the rear frame <NUM>. The lower end part of the rear frame left part 21a is rotatably coupled to the left shaft 20a. The rear frame right part 21b is disposed on the right end part of the rear beam 10c of the rear frame <NUM>. The lower end part of the rear frame right part 21b is rotatably coupled to the right shaft 20b. The rear frame upper part 21c is joined to the respective upper end parts of the rear frame left part 21a and the rear frame right part 21b. The rear frame upper part 21c extends in the vehicle width direction.

The left upper frame <NUM> is attached to the rear frame left part 21a. The left upper frame <NUM> extends from the upper end part of the rear frame left part 21a toward the front. The left lower frame <NUM> is attached to the rear frame left part 21a. The left lower frame <NUM> extends from the lower end part of the rear frame left part 21a toward the front. The left lower frame <NUM> is supported by the left beam 10a of the rear frame <NUM> when the cover frame <NUM> is closed. The first left upright frame 24a and the second left upright frame 24b are respectively connected to the left upper frame <NUM> and the left lower frame <NUM>. The first left upright frame 24a and the second left upright frame 24b both extend in the up-down direction. The first left upright frame 24a is disposed in front of the second left upright frame 24b.

The right upper frame <NUM> is attached to the rear frame right part 21b. The right upper frame <NUM> extends from the upper end part of the rear frame right part 21b toward the front. The right lower frame <NUM> is attached to the rear frame right part 21b. The right lower frame <NUM> extends from the lower end part of the rear frame right part 21b toward the front. The right lower frame <NUM> is supported by the right beam 10b of the rear frame <NUM> when the cover frame <NUM> is closed. The first right upright frame 27a and the second right upright frame 27b are respectively connected to the right upper frame <NUM> and the right lower frame <NUM>. The first right upright frame 27a and the second right upright frame 27b both extend in the up-down direction. The first right upright frame 27a is disposed in front of the second right upright frame 27b.

The upper frame <NUM> is formed overall as a U-shape. Both end parts of the upper frame <NUM> are connected to the rear frame upper part 21c. The upper frame <NUM> is supported by the left upper frame <NUM> and the right upper frame <NUM>.

The shield plate <NUM> is attached to the right upper frame <NUM>. The shield plate <NUM> is a member for suppressing the malfunction of a sensor (not shown) due to the effects of electromagnetic waves from outside. While the type of sensor protected by the shield plate <NUM> is not limited in particular, the sensor may be, for example, an NOx sensor. The NOx sensor measures the concentration of NOx gas included in the exhaust gas passing through a selective catalytic reduction (SCR) device. In the present embodiment, the shield plate <NUM> is disposed on the right side of the sensor.

The intake pipe <NUM> and the exhaust pipe <NUM> are disposed on the cover frame <NUM>. The intake pipe <NUM> and the exhaust pipe <NUM> are respectively supported by the left upper frame <NUM> and the right upper frame <NUM>.

The electric cylinder <NUM> is coupled to the vehicle body frame <NUM> and the cover frame <NUM>. Specifically, the electric cylinder <NUM> is coupled to the left beam 10a of the rear frame <NUM> of the vehicle body frame <NUM> and the rear frame left part 21a of the cover frame <NUM>. When the electric cylinder <NUM> extends, the cover frame <NUM> transitions to an open state. When the electric cylinder <NUM> contracts, the cover frame <NUM> transitions to a closed state. The cover frame <NUM> constitutes the skeleton of the engine hood <NUM> and therefore the opening and closing of the cover frame <NUM> has the same meaning as the opening and closing of the engine hood <NUM>.

The electric cylinder <NUM> is disposed on the left side based on the center in the vehicle width direction of the wheel loader <NUM>. The left side in the center of the vehicle width direction is an example of "one end side" according to the present invention. The electric cylinder <NUM> is positioned on the opposite side of the gas damper <NUM> in reference to the center in the vehicle width direction of the wheel loader <NUM>. When opening and closing the cover frame <NUM>, the electric cylinder <NUM> supports the left rear end part of the engine hood <NUM>.

As illustrated in <FIG>, the electric cylinder <NUM> has a casing <NUM>, a screw shaft <NUM>, and an electric motor <NUM>. The casing <NUM> is formed in a cylindrical shape. A lower end part of the casing <NUM> is rotatably coupled to the left beam 10a of the rear frame <NUM>. The casing <NUM> accommodates the screw shaft <NUM>. The screw shaft <NUM> extends and contracts due to the driving power of the electric motor <NUM>. An upper end part of the screw shaft <NUM> is rotatably coupled to the rear frame left part 21a. The electric motor <NUM> causes the screw shaft <NUM> to extend and contract due to electrical power supplied from a chargeable battery (not illustrated) that can be charged during the driving of the engine <NUM>. The electric motor <NUM> generates driving power sufficient for the opening and closing actions the cover frame <NUM>.

The gas damper <NUM> is coupled to the vehicle body frame <NUM> and the cover frame <NUM>. Specifically, the gas damper <NUM> is coupled to the right beam 10b of the rear frame <NUM> of the vehicle body frame <NUM> and the rear frame right part 21b of the cover frame <NUM>.

The gas damper <NUM> is disposed on the right side based on the center in the vehicle width direction of the wheel loader <NUM>. The right side in the center of the vehicle width direction is an example of "other end side" according to the present invention. The gas damper <NUM> is positioned on the opposite side of the electric cylinder <NUM> in reference to the center in the vehicle width direction of the wheel loader <NUM>.

The gas damper <NUM> according to the present embodiment constantly biases the right rear end part of the cover frame <NUM> regardless of whether the cover frame <NUM> is in the open state or closed state. Therefore, the gas damper <NUM> biases the right rear end part of the cover frame <NUM> not only when the cover frame <NUM> is opened and closed but also while the cover frame <NUM> is in the open state. Therefore, the gas damper <NUM> supports the cover frame <NUM> along with the electric cylinder <NUM> when the cover frame <NUM> is in the open state in addition to assisting the electric cylinder <NUM> when the cover frame <NUM> is opened and closed.

As illustrated in <FIG>, the gas damper <NUM> has a tube <NUM> and a rod <NUM>. The tube <NUM> is formed in a cylindrical shape. An upper end part of the tube <NUM> is rotatably coupled to the rear frame right part 21b. The tube <NUM> accommodates the rod <NUM>. Compressed gas is sealed between the tube <NUM> and the rod <NUM>. The rod <NUM> extends due to the counterforce of the compressed gas. The inside of the gas damper <NUM> is not provided with an orifice for damping the counterforce of the compressed gas. As a result, the right rear end part of the cover frame <NUM> continues to be urged even when the cover frame <NUM> is supported in the open state.

The wheel loader <NUM> according to the present embodiment has the vehicle body frame <NUM>, the cover frame <NUM>,, the electric cylinder <NUM>, and the gas damper <NUM>. The cover frame <NUM> is coupled to the vehicle body frame <NUM> so as to allow opening and closing. The electric cylinder <NUM> is coupled to the vehicle body frame <NUM> and the cover frame <NUM> and is disposed on the left side based on the center in the vehicle width direction of the wheel loader <NUM>. The gas damper <NUM> is coupled to the vehicle body frame <NUM> and the cover frame <NUM> and is disposed on the right side based on the center in the vehicle width direction of the wheel loader <NUM>.

In this way, both the left and right sides of the cover frame <NUM> are supported by the electric cylinder <NUM> and the gas damper <NUM> and therefore the cover frame <NUM> assume a twin support state in the wheel loader <NUM>. As a result, while the cover frame <NUM> is open, and when the cover frame <NUM> is opened or closed, the occurrence of deformation of the cover frame <NUM> or shaking of the cover frame <NUM> is suppressed. Consequently, the matter of the engine hood <NUM> coming into contact with a peripheral member can be suppressed.

In particular, although the weight of the engine hood <NUM> is increased by the steps <NUM>, the shield plate <NUM>, and the intake pipe <NUM> and the like which are provided to the engine hood <NUM> in the present embodiment, even then deformation and shaking of the cover frame <NUM> can be effectively suppressed. Furthermore, although the engine hood <NUM> extends in the front-back direction and thus has a shape that is likely to lead to deformation or shaking of the engine hood <NUM> in the present embodiment, even then deformation and shaking of the cover frame <NUM> can be effectively suppressed.

Furthermore, the electric cylinder <NUM> is used as an example of a first extendable member in the present embodiment. As a result, if a battery for driving the extension and contraction is installed, the cover frame <NUM> can be opened or closed even if the engine <NUM> is stopped. In contrast, if a hydraulic cylinder, for example, were used as the first extendable member, normally the cover frame <NUM> could not be opened or closed if the engine <NUM> were not operating because the engine <NUM> and the hydraulic pump are stopped.

Furthermore, the gas damper <NUM> is used as an example of the second extendable member in the present embodiment. As a result, not only can the cover frame <NUM> be opened or closed even if the engine <NUM> is stopped, there is no need to install a battery for driving the extension and contraction. Furthermore, the cost can be suppressed in comparison to when using an electric cylinder or a hydraulic cylinder as the second extendable member.

Furthermore, the gas damper <NUM> in the present embodiment biases the cover frame <NUM> when the cover frame <NUM> is in the open state. Therefore, deformation or shaking of the cover frame <NUM> in the open state can be effectively suppressed in comparison to when using a gas damper of a type that does not impart a biasing force when in the extended state (e. , a gas damper with an orifice).

Although an embodiment of the present invention has been described so far, the present invention is not limited to the above embodiment and various modifications may be made within the scope of the invention, as defined in the appended claims.

While the electric cylinder <NUM> in disposed on the left side and the gas damper <NUM> is disposed on the right side in the above embodiment, the electric cylinder <NUM> may be disposed on the right side and the gas damper <NUM> may be disposed on the left side.

While no orifice is provided inside the gas damper <NUM> in the above embodiment, an orifice may be provided.

While the front end part of the engine hood <NUM> is configured to be lifted upward and rearward in the above embodiment, the rear end part of the engine hood <NUM> may be configured to be lifted upward and forward.

While the steps <NUM>, the shield plate <NUM>, and the intake pipe <NUM> and the like are provided to the engine hood <NUM> in the above embodiment, said members may be provided optionally.

While configurations of the rear frame <NUM> and the cover frame <NUM> have been explained in the above embodiment with reference to <FIG> and <FIG>, said configurations mat be changed as appropriate.

While the engine hood <NUM> is coupled to the rear frame <NUM> in the above embodiment, the engine hood <NUM> may be coupled to the front frame <NUM>.

Claim 1:
A work vehicle comprising:
a vehicle body frame (<NUM>) configured to support an engine (<NUM>);
an engine hood (<NUM>) having a cover frame (<NUM>) constituting a skeleton of the engine hood (<NUM>), wherein the cover frame (<NUM>) is coupled to the vehicle body frame (<NUM>) so as to allow opening and closing, and an engine cover (<NUM>) attached to the cover frame (<NUM>);
a first extendable member (<NUM>) coupled to the vehicle body frame (<NUM>) and the cover frame (<NUM>), the first extendable member (<NUM>) disposed at one end side based on a center in a vehicle width direction of the work vehicle;
a second extendable member (<NUM>) coupled to the vehicle body frame (<NUM>) and the cover frame (<NUM>), the second extendable member (<NUM>) disposed at other end side based on the center in the vehicle width direction of the work vehicle;
wherein the one extendable member (<NUM>, <NUM>) among the first extendable member (<NUM>) and the second extendable member (<NUM>) is an electric cylinder; and
wherein the other extendable member (<NUM>, <NUM>) among the first extendable member (<NUM>) and the second extendable member (<NUM>) is a gas damper.