EP3591211B1

EP3591211B1 - Work vehicle

Info

Publication number: EP3591211B1
Application number: EP19175231.0A
Authority: EP
Inventors: Takashi KUMASHIRO; Hiroki Nagai; Tomohisa Yamamoto; Toshiki Kanai; Takeshi Komorida; Akihito Mihara; Tatsuro TOKUNAGA; Kazutomo Miyaguchi; Taisuke Hashimoto; Ryo Matsumoto; Yuto FUJII
Original assignee: Kubota Corp
Current assignee: Kubota Corp
Priority date: 2018-06-15
Filing date: 2019-05-17
Publication date: 2024-01-31
Anticipated expiration: 2039-05-17
Also published as: EP3591211A2; EP3591211A3

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to work vehicles, and specifically relates to riding work vehicles such as tractors.

2. Description of the Related Art

(1) First Related Art

JP 2015-163512A (or EP 3 109 085 A1 corresponding thereto) discloses a work vehicle provided with an air cleaner that cleans air supplied to an engine. This work vehicle is provided with a hood located forward of a driver section, and an engine is provided inside the hood. An air cleaner that takes in external air, removes dust or the like from the external air that has been taken in, and supplies clean air to the engine is provided inside the hood. This air cleaner extends in a front-rear direction of the machine body of the work vehicle, and clean air from the air cleaner is supplied to the engine via a turbocharger, which is a pipe extending in the front-rear direction of the machine body. Thus, clean air can be supplied to the engine.
The turbocharger is a pipe extending in the front-rear direction of the machine body, and is attached to an upper end portion of the engine. Therefore, clean air from the air cleaner is supplied to the engine via a pipe that is bent toward the upper end portion of the engine at the rear end in the front-rear direction of the machine body. Here, the engine takes in air from a portion where the engine is connected to the pipe, and noise generated in the portion where the engine takes in air reaches the driver section located rearward of the engine.
An object of the invention is to provide a work vehicle that can reduce noise that reaches the driver section.

(2) Second Related Art

WO 03/054373 and JP2011-021571A disclose each a similar vehicle with a coupling tube coupled between the engine and the air cleaner and extending in a right-left direction.

SUMMARY OF THE INVENTION

A work vehicle as below is proposed in correspondence with First Related Art:
A work vehicle comprising:

a travel vehicle body;
a prime mover section that is provided in a front portion of the travel vehicle body;
a hood that covers the prime mover section;
a driver section that is provided rearward of the prime mover section, the driver section having a driver seat;
an engine that is provided inside the hood;
an air cleaner that is provided inside the hood above the engine for processing external air that is to be supplied to the engine;
an intake tube that is coupled to the air cleaner for taking air into the air cleaner; and
a coupling tube that is coupled between the engine and the air cleaner for supplying, to the engine, processed air that is provided by passing external air through the air cleaner, the coupling tube being coupled to the engine and extending in a right-left direction of the travel vehicle body and being coupled to the air cleaner. The coupling tube includes a third pipe that is coupled to an upper opening of the engine, a second pipe that curves upward and to the right from the third pipe and extends in a right-left direction of the travel vehicle body, and a first pipe that curves from the second pipe toward an exhaust portion provided on one lateral side of the air cleaner for discharging the processed air, and extends toward the air cleaner, wherein the first pipe extends forward and to the right from the exhaust portion, curves forward and to the left, and is coupled to the second pipe, and the second pipe of the coupling tube is formed larger in size or diameter than the first pipe and the third pipe of the coupling tube. The air cleaner has a longitudinally elongated cylindrical shape, with a longitudinal direction extending parallel with the right-left direction of the travel vehicle body.

With this configuration, the coupling tube between the air cleaner and the engine is coupled to the engine, while extending in the right-left direction of the travel vehicle body and being coupled to the air cleaner. The coupling tube includes a section that extends in the right-left direction of the travel vehicle body, and therefore processed air flowing through the coupling tube also flows in the right-left direction and is brought to the engine. Therefore, at least some of the noise generated in an intake portion where the engine is coupled to the coupling tube and from which processed air is taken into the engine does not travel rearward of the travel vehicle body, but instead travels in the right-left direction of the travel vehicle body along with the processed air flowing in the right-left direction. As a result, it is possible to reduce noise generated in the intake portion and travelling toward the driver section provided rearward of the air cleaner and the engine.
Moreover, because the longitudinal direction of the air cleaner is parallel with the right-left direction of the travel vehicle body, a larger amount of external air taken in by the air cleaner flows in the right-left direction than in the front-rear direction. Therefore, it is possible to further reduce noise generated in the intake portion and travelling toward the driver section provided rearward of the air cleaner and the engine.
In one preferred embodiment, the coupling tube extends from the engine in the right-left direction of the travel vehicle body, thereafter curves toward the exhaust portion, and is coupled to the exhaust portion.
With the above-described configuration, in addition to the fact that the longitudinal direction of the air cleaner is parallel with the right-left direction of the travel vehicle body, the exhaust portion is provided on a side of the air cleaner. Therefore, while a configuration in which the coupling tube coupled to the engine extends in the right-left direction is employed, the coupling tube can be easily connected to the air cleaner.
In one preferred embodiment, the intake tube extends from a portion where the intake tube is coupled to the air cleaner, thereafter extends to a position forward of the air cleaner, and curves and extends to a position that is rearward with respect to the travel vehicle body.
With the above-described configuration, the intake tube does not extend rearward directly from the air cleaner, but instead first extends to a position that is forward of the air cleaner, and thereafter curves and extends rearward. Therefore, the flow in the front-rear direction of air taken in from an open end of the intake tube is weakened in the curved portion. As a result, it is possible to further reduce noise travelling toward the driver section.
In one preferred embodiment, the work vehicle further includes a radiator that is provided rearward of the engine and cools cooling water for cooling the engine; and a cooling fan that is provided immediately forward of the radiator, and an end portion, from which external air is taken in, of the intake tube is located rearward of the radiator.
With the above-described configuration, the rear end portion of the intake tube is located rearward of the radiator. Therefore, it is possible to realize a configuration in which cooling air that has not been supplied to the radiator is taken into the air cleaner via the intake tube. As a result, it is unlikely that incomplete combustion occurs in the engine due to the lack of air.
Other features and advantages produced thereby will become apparent by reading the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a left side view of a tractor according to a first embodiment (the same applies up to Fig. 8);
Fig. 2 is a plan view of the tractor;
Fig. 3 is a rear view of the tractor;
Fig. 4 is a left side view showing space in an engine room of a prime mover section;
Fig. 5 is a plan view showing configurations of an air cleaner, a coupling tube and an intake tube.
Fig. 6 is a left side view showing an arrangement of light units according to another embodiment;
Fig. 7 is a side view showing an example of a configuration of an HST linkage mechanism; and
Fig. 8 is a perspective view of an HST linkage stay shown in Fig. 7.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIRST EMBODIMENT

In the first embodiment, a tractor is an example of the work vehicle.
In the following description, unless explicitly described otherwise, "front" refers to the direction in which the tractor travels forward during working travel (see arrows F in Figs. 1 and 2), "rear" refers to the direction in which the tractor travels rearward (see arrows B in Figs. 1 and 2), "right" refers to the direction corresponding to the right side relative to the forward orientation of the tractor in the front-rear direction (see an arrow R in Fig. 2), and "left" refers to the direction corresponding to the left side (see an arrow L in Fig. 2). "Up" refers to the direction corresponding to the upper side (see an arrow T in Fig. 1), and "down" refers to the direction corresponding to the lower side (see an arrow D in Fig. 1).

Overall Configuration

The tractor in the present embodiment, which is an example of a work vehicle, is configured as described below.
As shown in Figs. 1 and 2, the tractor is constituted by a travel vehicle body 100 that includes a vehicle body frame 1, which forms a framework of a vehicle body, a prime mover section 2, which is supported on the front side of the vehicle body frame 1, a riding-type driver section 4, which is located on the rear side of the vehicle body frame 1, right and left traveling apparatuses 5, a protection frame 6, which is coupled to a rear end portion of the vehicle body frame 1, etc.
The right and left travel apparatuses 5 are of a four-wheel drive type, including right and left front wheels 5A, which are steerable and are driven by power from the prime mover section 2, and right and left rear wheels 5B, which are driven by power from the prime mover section 2.
As shown in Figs. 1 to 4, the vehicle body frame 1 includes a pair of right and left side members 10 that are made of steel plates and extend in the front-rear direction, and a front member 11 that is made of a steel plate and spans between the front ends of the right and left side members 10.
In addition, a center pillar 12 spans between the right and left side members 10 at a substantially central position in the front-rear direction of the right and left side members 10. Also, a transmission 13 is attached to a position near rear end portions of the right and left side members 10 for transmitting power from an engine 21 provided in the prime mover section 2 to the right and left traveling apparatuses 5 and so on, while performing speed conversion.
An HST (Hydrostatic Transmission) 50 is provided in the transmission 13 as an example of a continuously variable transmission mechanism, correspondingly to the right and left front wheels 5A and the right and left rear wheels 5B in the right and left travel apparatuses 5. A driver section step 15 described below is provided with an HST operation pedal 51. Upon the HST operation pedal 51 being operated, the operation performed on the HST operation pedal 51 is transmitted to the HST 50 via an HST linkage mechanism (not shown), and the HST 50 is subjected to continuously variable speed conversion.
In the driver section 4 provided rearward of the prime mover section 2, a driver seat 42 is located above the transmission 13; the driver section step 15 on which the driver can ride is provided within the gap between the driver seat 42 and the prime mover section 2 in the front-rear direction; and rear wheel fenders 16 are provided on the right and left sides of the driver seat 42.
A dashboard 40 is provided at a position located rearward of the hood 20 of the prime mover section 2. The dashboard 40 is provided with a steering wheel 41 for steering the front wheels, and indicators that indicate the engine speed and so on, and functions as a member that constitutes a part of the driver section 4.
As shown in Fig. 4, a throttle lever 27 that is used to operate a throttle of the engine is provided at a position on the lateral side of the body of the engine 21. The throttle lever 27 is supported so as to be pivotable in a horizontal direction about a vertical axis y1 as shown in Fig. 4, and an accelerator wire 28 is coupled to the leading end of the throttle lever 27.
Therefore, the accelerator wire 28 is pushed and pulled in response to an operation performed using an accelerator operation tool 29 that is provided in the driver section 4, and accordingly the rotation angle of the throttle lever 27 is changed and the speed of the rotation engine 21 is adjusted.
A partition 3 described below is provided between the driver section step 15 and a lower portion of the above-described dashboard 40.
Therefore, while being used as a constituent element of the driver section 4 equipped with indicators or the like, the dashboard 40 also functions as an upper lid of the partition 3, and as a member of the prime mover section 2 constituting a part of an engine room 2A of the prime mover section 2 together with the partition 3.
The partition 3 is a combination of a main frame 30 that is grid-shaped, and an external wall plate 31 having a large number of ventilation holes and provided on the rear surface of the main frame 30.
The partition 3 is provided at a position below the dashboard 40 and above the driver section step 15. An intermediate portion of the partition 3 in the right-left direction bulges rearward, and the partition 3 is substantially gate-shaped in plan view. A battery 26 is housed in space on the inner peripheral side of the partition 3 that is gate-shaped in plan view.

Prime mover section

The prime mover section 2 has a configuration described below.
As shown in Figs. 1 to 4, in the prime mover section 2, space located forward of the center pillar 12 fixed so as to span between the right and left side members 10 defines an engine room 2A that is covered by the hood 20. In a space that is rearward of the center pillar 12, the dashboard 40 that constitutes a part of the driver section 4 is provided above the partition 3. Thus, the space covered by the hood 20 and the space inside the partition 3 constitute the engine room 2A that is the internal space of the prime mover section 2.
The engine 21, which is a water-cooled type gasoline engine supported on a front portion of the vehicle body frame 1 so as to be vibration-proof, is provided in the engine room 2A. Furthermore, a cooling fan 22 that is located rearward of the engine 21, a radiator 23 that is located rearward of the cooling fan 22, an air cleaner 24 that is located above the engine 21, a muffler 25 that is located forward of the engine 21, and so on are provided in the engine room 2A.
The hood 20 is of an integrated type in which a front cover 20a that covers a front end portion of the prime mover section 2 and allows air to pass, right and left side covers 20b that cover lateral side portions of the prime mover section 2, an upper cover 20c that covers an upper portion of the prime mover section 2, head light units 20d, and so on are coupled to each other and integrated into one piece. This hood 20 is configured to be able to swing to open and close in the up-down direction about a pivot axis x1 located at a front end portion of the vehicle body frame 1 and extending in the right-left direction.
Thus, the hood 20 is configured to be able to swing in a up-down direction between a closed position where the hood 20 covers the prime mover section 2 and an open position where the hood 20 does not cover the prime mover section 2, and is configured to be of a rear-open type, i.e. a rear portion of the space inside the hood 20 is wide open when the hood 20 is in the open position. As a result, it is easy to perform maintenance work on the radiator 23, the air cleaner 24 and so on provided in a rear portion of the prime mover section 2.
The radiator 23 is provided in a rear end portion of the engine room 2A, and the cooling fan 22 for taking in external air and bringing the external air into contact with the radiator 23 is provided in the engine room 2A at a position that is forward of the radiator 23. External air that is to be supplied to the radiator 23 passes through the partition 3 on the rear side, and is taken in and brought to the radiator 23 as indicated by the arrow in Fig. 4, cools the radiator 23, the engine 21 and the muffler 25, and is thereafter discharged from a portion of the front cover 20a on the front side.
The air cleaner 24 is provided inside the hood 20 at a position above the engine 21 and forward of the radiator 23. An intake tube 61 that is used to take in external air is coupled to the air cleaner 24. Also, a coupling tube 63 is coupled between the engine 21 and the air cleaner 24. The air cleaner 24 takes in external air via the intake tube 61, performs dust removal processing to remove dust such as cut grass and sand, and supplies the processed air to the engine 21 via the coupling tube 63.

Air Cleaner, Coupling Tube and Intake Tube

The following further describes the configuration of the air cleaner 24 with reference to Figs. 4 and 5.
The air cleaner 24 has an elongated cylindrical shape and its longitudinal direction extends parallel with the right-left direction of the travel vehicle body 100. The air cleaner 24 includes a cylindrical side portion 24b that extends in the right-left direction, and a left side portion 24c and a right side portion 24d that are respectively located at the ends of the cylindrical side portion 24b in the right-left direction. An air intake port 24a from which external air is taken in is provided near the left side portion 24c of the air cleaner 24. The air intake port 24a is open rearward and obliquely downward at a position that is rearward of the engine 21 with respect to the machine body, and is forward of the radiator 23. External air passing through the partition 3 and the radiator 23 is taken in from the air intake port 24a to the inside of the air cleaner 24.
A protrusion 24e is provided on the cylindrical side portion 24b of the air cleaner 24 so as to protrude forward and obliquely upward from the cylindrical side portion 24b. Also, an exhaust portion 24f is provided in the right side portion 24d of the air cleaner 24 such that the processed air subjected to dust removal processing performed by the air cleaner 24 may be discharged from the air cleaner 24.
The intake tube 61 for taking in external air to the air cleaner 24, and the coupling tube 63 extending from the air cleaner 24 and coupled to the engine 21, are connected to the air cleaner 24.
The intake tube 61 is connected to the protrusion 24e of the air cleaner 24. Therefore, the intake tube 61 extends along the protrusion 24e to a position that is forward of the air cleaner, and thereafter extends to a position that is rearward of the travel vehicle body 100. As a result, the intake tube 61 includes an intake open end portion 61a that is open at the rear end, an intake elongated portion 61b that extends from the intake open end portion 61a in the front-rear direction, an intake curved portion 61c that extends forward from the protrusion 24e and curves rearward toward the left, and an intake connection end portion 61d that is connected to the protrusion 24e.
The intake open end portion 61a (the rear end portion of the intake tube 61) is located near the front side of the radiator 23 with a gap therefrom, for example. External air is taken in from the intake open end portion 61a, and is brought to the air cleaner 24 via the intake elongated portion 61b, the intake curved portion 61c and the intake connection end portion 61d.
The coupling tube 63 is coupled to the exhaust portion 24f provided on the right side portion 24d of the air cleaner 24, and sends out processed air in the air cleaner 24 to the engine 21. Specifically, the coupling tube 63 is coupled to the engine 21, and also extends in the right-left direction of the travel vehicle body 100, thereafter curves toward the exhaust portion 24f, and is coupled to the exhaust portion 24f. The coupling tube 63 includes a third pipe 63c that is coupled to an upper opening of the engine 21, a second pipe 63b that curves upward and to the right from the third pipe 63c and extends in the right-left direction, and a first pipe 63a that curves toward the exhaust portion 24f from the second pipe 63b and extends toward the air cleaner 24.
The first pipe 63a extends forward and to the right from the exhaust portion 24f, thereafter curves forward and to the left, and is coupled to the second pipe 63b. The second pipe 63b extends in the right-left direction from the first pipe 63a, and is coupled to the third pipe 63c. The second pipe 63b extends downward from a left portion of the portion extending in the right-left direction such that the second pipe 63b can be coupled to the third pipe 63c. The third pipe 63c is coupled to the upper opening of the engine 21, and extends in the up-down direction. The third pipe 63c may curve toward the second pipe 63b so as to be coupled to the second pipe 63b.
With the above-described configuration, the coupling tube 63 between the air cleaner 24 and the engine 21 is coupled to the engine 21, while extending in the right-left direction of the travel vehicle body 100 and being coupled to the air cleaner 24. The coupling tube 63 includes the second pipe 63b that extends in the right-left direction of the travel vehicle body 100, and therefore processed air flowing through the coupling tube 63 also flows in the right-left direction and is brought to the engine 21. Therefore, at least some of the noise generated in an intake portion where the engine 21 is coupled to the coupling tube 63 and from which processed air is taken into the engine 21 does not travel rearward of the travel vehicle body 100, but instead travels in the right-left direction of the travel vehicle body 100 along with the processed air flowing in the right-left direction. As a result, it is possible to reduce noise generated in the intake portion and travelling toward the driver section 4 provided rearward of the air cleaner 24 and the engine 21.
In this connection, it is known that noise generated in the intake portion is dominant over noise generated in the coupling tube 63, the air cleaner 24 and so on. Therefore, reducing noise generated in the intake portion is effective for reducing noise travelling toward the driver section 4.
Note that if the coupling tube 63 between the air cleaner 24 and the engine 21 does not extend in the right-left direction, but instead extends rearward with respect to the travel vehicle body 100 and is coupled to the air cleaner 24, processed air that is brought from the air cleaner 24 to the engine 21 via the coupling tube 63 travels in the front-rear direction of the travel vehicle body 100. Therefore, noise generated in the intake portion where the engine 21 and the coupling tube 63 are coupled to each other travels rearward along with processed air flowing in the front-rear direction. For example, when the tractor travels forward, processed air flows rearward inside the hood 20, and noise travels further rearward toward the driver section 4. With the above-described configuration, however, it is possible to reduce noise travelling toward the driver section 4.
Also, the longitudinal direction of the air cleaner 24 extends parallel with the right-left direction of the travel vehicle body 100, and therefore, external air taken in by the air cleaner 24 mainly flows in the right-left direction compared to the front-rear direction. Therefore, it is possible to further reduce noise generated in the aforementioned intake portion and travelling toward the driver section 4 provided rearward of the air cleaner 24 and the engine 21.
In addition to the fact that the longitudinal direction of the air cleaner 24 extends parallel with the right-left direction of the travel vehicle body 100, the exhaust portion 24f is provided in the right side portion 24d of the air cleaner 24. Therefore, while the coupling tube 63 coupled to the engine 21 extends in the right-left direction, the coupling tube 63 can be easily connected to the air cleaner 24.
Also, the intake tube 61 includes the intake curved portion 61c that does not extend rearward directly from the air cleaner 24, but instead first extends to a position that is forward of the air cleaner 24 and thereafter curves and extends rearward. Therefore, the flow of air taken in from the intake open end portion 61a of the intake tube 61 is weakened in the curved portion. As a result, it is possible to further reduce noise travelling toward the driver section 4.
As the air cleaner 24 is provided with the air intake port 24a and the intake tube 61, external air can be taken in from a plurality of positions. Therefore, it is possible to ensure that a sufficient amount of air is supplied to the engine 21. As a result, it is unlikely that incomplete combustion occurs in the engine 21 due to the lack of air.

Protection Frame

The following further describes the configuration of the protection frame 6 with reference to Figs. 1 to 3.
As shown in Figs. 1 to 3, the protection frame 6 that is gate-shaped and is coupled to the rear end portion of the vehicle body frame 1 is provided in a rear portion of the driver seat 42.
This gate-shaped protection frame 6 includes right and left supporting posts 6a and a coupling member 6b. The right and left supporting posts 6a are located rearward of the driver seat 42 on the right and left sides respectively. The right and left supporting posts 6a extend in the up-down direction, and extend toward the center in the right-left direction from the upper end portions so as to oppose each other. The upper end portions, which oppose each other, of the right and left supporting posts 6a are not continuous. The upper end portions, which oppose each other, of the right and left supporting posts 6a are coupled to each other by the coupling member 6b. That is to say, a center-side end of the upper end portion of the left supporting post 6a and an end portion of the coupling member 6b are fixed by fastening members 6b1, and a center-side end of the upper end portion of the right supporting post 6a and an end portion of the coupling member 6b are fixed by fastening members 6b 1.
With the above-described configuration of the protection frame 6, the protection frame 6 can be assembled by fitting the right and left supporting posts 6a to the travel vehicle body 100, and thereafter fixing them using the coupling members 6b. Therefore, the protection frame 6 can be easily assembled. The right and left supporting posts 6a curve at lower portions where are attached to the travel vehicle body 100, and also curve at upper portions. Therefore, only the right and left supporting posts 6a include curved portions. Also, the right and left supporting posts 6a have the same shape, and they can be manufactured more easily than when right and left members that are different from each other are manufactured.

Other Embodiments modified from First Embodiment

(1) In the above-described embodiment, the air cleaner 24 is positioned such that the longitudinal direction thereof coincides with the right-left direction. However, it suffices if a section of the coupling pipe 63 extending from the engine 21 to the air cleaner 24 at least includes the second pipe 63b that extends in the right-left direction. Therefore, for example, the air cleaner 24 may be positioned such that the longitudinal direction thereof coincides with the front-rear direction. It suffices if the coupling tube 63 extends in the right-left direction, and is coupled to a side portion of the air cleaner 24 in the longitudinal direction, i.e. the cylindrical side portion 24b shown in Fig. 5. Alternatively, the coupling tube 63 may extend in the right-left direction, and may be coupled to a front end portion of the air cleaner 24 in the longitudinal direction (the right side portion 24d or the left side portion 24c shown in Fig. 5).
In the above-described embodiment, the shape of the air cleaner 24 is cylindrical, but this is not limitative. Instead thereof, the air cleaner 24 may be formed in shape of e.g. rectangular parallelepiped, ellipsoid, sphere, truncated cone, truncated pyramid, etc.
(2) In the above-described embodiment, the air cleaner 24 includes the protrusion 24e that protrudes forward and obliquely upward. However, it suffices if the intake tube 61 is coupled to the air cleaner 24 so as to extend rearward from the air cleaner 24, and the protrusion 24e does not necessarily have to protrude forward and obliquely upward. For example, the protrusion 24e may protrude rearward. However, in the above-described embodiment, the protrusion 24e protrudes forward and obliquely upward and is connected to the intake tube 61, and accordingly the intake tube 61 includes the intake curved portion 61c. Whereby, the flow of air taken in from the intake open end portion 61a of the intake tube 61 is weakened in the intake curved portion 61c. As a result, it is possible to further reduce the amount of noise travelling toward the driver section 4.
(3) Although the air cleaner 24 includes the air intake port 24a in the above-described embodiment, it does not necessarily have to provide the air intake port 24a. Also, it does not necessarily have to provide the air intake port 24a in the vicinity of the left side portion 24c, and may be provided in the right side portion 24d, or in the cylindrical side portion 24b.
(4) In the above-described embodiment, the exhaust portion 24f is provided in the right side portion 24d. However, the exhaust portion 24f may be provided in the left side portion 24c, and the first pipe 63a that extends from the exhaust portion 24f forward and to the left and thereafter curves to the right may be connected to the exhaust portion 24f, and the second pipe 63b that extends in the right-left direction and the third pipe 63c that is connected to the engine 21 may also be connected.
(5) Although the above-described embodiments illustrates a structure in which a water-cooled type gasoline engine is employed as the engine 21 that is provided in the prime mover section 2, this is not limitative. For example, an air-cooled type gasoline engine may be employed as the engine 21. Also, a structure in which a diesel engine is employed instead of a gasoline engine, or a structure provided with a discharge processing device with a DPF (diesel particulate filter) may be employed.
Furthermore, the prime mover section 2 may be of a hybrid type provided with the engine 21 and an electric motor.
Regarding other configurations, the same configurations as those in the above-described embodiment may be employed.
(6) In the above-described embodiment, the intake open end portion 61a (the rear end portion of the intake tube 61) is located in the vicinity of the front end of the radiator 23. However, the intake open end portion 61a may be located rearward of the radiator 23. In this case, cooling air before supply to the radiator 23 may be taken into the air cleaner 24 via the intake open end portion 61a.
(7) In the above-described embodiment, the hood 20 is provided with the head light units 20d. However, light units are not limited to the head light units 20d, and may be provided at a plurality of positions on the travel vehicle body 100 as shown in Fig. 6. In Fig. 6, the tractor may be provided with, in addition to the head light units 20d on a front portion of the hood 20, a light unit 71 on the upper surface of the hood 20, light units 72 on the side portions of the rear wheel fenders 16, light units 73 on the upper surfaces of the rear wheel fenders 16, light units 74 on the rear surfaces of the rear wheel fenders 16, and so on. With the light units provided at a plurality of positions all over the travel vehicle body 100, light can be emitted in all directions around the tractor, which makes work easier even when it is dark, such as in the evening or at night.
(8) The above-described embodiment does not specifically refer to the configuration of the HST linkage mechanism (continuously variable transmission mechanism). However, the HST linkage mechanism may include an HST linkage stay 90 shown in Figs. 7 and 8.

An HST linkage mechanism 120 shown in Figs. 7 and 8 is a mechanism for transmitting an operation performed on the HST operation pedal 51 to the HST 50. Upon the HST operation pedal 51 being operated, the HST linkage stay 90 swings about a shaft 95 in response to the operation, the inclined plate (not shown) of the HST 50 is controlled by the swing, and an output from the HST 50 is controlled.
The HST linkage stay 90 is made of a single plate, and has a polygonal shape with a plurality of protrusions as a result of protrusions and recesses being formed along the plate surface. The shaft 95 is formed on one protrusion, and through holes 91, 92, 93, and 94 are formed in protrusions at other positions. The shaft 95 of the HST linkage stay 90 is coupled to the vehicle body frame 1 (Fig. 1, etc.) so as to be swingable. An end portion of a rod 83 that couples the HST 50 and the HST linkage stay 90 to each other is pivotably supported by the through hole 92. The through hole 91 is used to couple another member (not shown) to the HST linkage stay 90.
The other through holes 93 and 94 are used in the following manner. A cylinder 81 for alleviating a rapid operation transmitted to the HST 50 is coupled to the HST linkage stay 90 via an interposed member 101. One end portion of the cylinder 81 is fixed to the vehicle body frame 1, and the other end portion is coupled to a fastening portion 101c of the interposed member 101. The through hole 93 of the HST linkage stay 90 is elongated, and a lock member 101b of the interposed member 101 is movable along the elongated through hole 93. A fastening portion 101a of the interposed member 101 is coupled to the through hole 94 of the HST linkage stay 90.
Upon the HST operation pedal 51 being operated, the cylinder 81 expands and contracts, and the lock member 101b of the interposed member 101 moves along the elongated through hole 93. Thus, a rapid operation transmitted to the HST 50 can be alleviated.
With the above-described configuration, the HST linkage stay 90 of the HST linkage mechanism 120 is made of a single plate, and the configuration can be simplified.
(9) In the above-described embodiment, the second pipe 63b of the coupling tube 63 is slightly larger than the first pipe 63a and the third pipe 63c.

Claims

A work vehicle comprising:
a travel vehicle body (100);

a prime mover section (2) that is provided in a front portion of the travel vehicle body (100);

a hood (20) that covers the prime mover section (2);

a driver section (4) that is provided rearward of the prime mover section (2), the driver section having a driver seat (42);

an engine (21) that is provided inside the hood (20);

an air cleaner (24) that is provided inside the hood (20) above the engine (21) for processing external air that is to be supplied to the engine (21);

an intake tube (61) that is coupled to the air cleaner (24) for taking air into the air cleaner (24); and

a coupling tube (63) that is coupled between the engine (21) and the air cleaner (24) for supplying, to the engine (21), processed air that is provided by passing external air through the air cleaner (24),

characterized in that the coupling tube (63) includes a third pipe (63c) that is coupled to an upper opening of the engine (21), a second pipe (63b) that curves upward and to the right from the third pipe (63c) and extends in a right-left direction of the travel vehicle body (100), and a first pipe (63a) that curves from the second pipe (63b) toward an exhaust portion (24f) provided on one lateral side of the air cleaner (24) for discharging the processed air, and extends toward the air cleaner (24); in that

the first pipe (63a) extends forward and to the right from the exhaust portion (24f), curves forward and to the left, and is coupled to the second pipe (63b); in that the second pipe (63b) of the coupling tube (63) is formed larger in size or diameter than the first pipe (63a) and the third pipe (63c) of the coupling tube (63); and in that the air cleaner (24) has a longitudinally elongated cylindrical shape, with a longitudinal direction extending parallel with the right-left direction of the travel vehicle body (100).
The work vehicle according to claim 1, wherein
the coupling tube (63) extends from the engine (21) in the right-left direction of the travel vehicle body (100), thereafter curves toward the exhaust portion (24f), and is coupled to the exhaust portion (24f).
The work vehicle according to any one of claims 1 or 2, wherein
the intake tube (61) extends from a portion where the intake tube (61) is coupled to the air cleaner (24), thereafter extends to a position forward of the air cleaner (24), and curves and extends to a position that is rearward with respect to the travel vehicle body (100).
The work vehicle according to claim 3, wherein the work vehicle further comprises:
a radiator (23) that is provided rearward of the engine (21) and cools cooling water for cooling the engine (21); and

a cooling fan (22) that is provided immediately forward of the radiator (23),

wherein an end portion of the intake tube (61) where external air is taken in is located rearward of the radiator (23).