JPS6365532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a shaft drive type rough terrain vehicle having at least three wheels fitted with wide ultra-low pressure tires.

(Background of the Invention) There are three-wheel or four-wheel vehicles equipped with a wide range of ultra-low pressure tires and whose rear wheels are driven by a shaft drive type rear wheel drive mechanism. In the shaft drive type, a final reduction gear is provided on the rear wheel shaft, and this final reduction gear is housed in a liquid-tight gear case. In this case, gear oil is placed in the gear case. The final reduction gear, gear case, and gear oil become hot when the wheels are running, and cool down after the wheels are stopped and left alone. When the internal pressure of the gear case changes due to such temperature changes, the sealing portion of the case is likely to be damaged. For this reason, the case is usually provided with a breather hole that communicates with the outside air so that the internal pressure of the case is always approximately the same as the outside air pressure.

On the other hand, this type of vehicle sometimes crosses swamps and rivers, and at such times the case of the final reduction gear may become submerged in water. In such a case, water enters through the breather hole provided in the case, causing a problem in that the gear oil deteriorates, lubrication of the gears deteriorates, and durability is significantly reduced.

Furthermore, in cold regions, if the breather hole is exposed to cold air, condensation will form in the breather hole, and if the engine is stopped and left for a long time, this may freeze and block the breather. Furthermore, the wind from the vehicle may cause ice to form on the breather hole, or a portion of the inside of the breather pipe may freeze, causing the breather pipe to become clogged. If the gear case cools and the internal pressure decreases, the breather pipe will collapse, and conversely, if the gear case becomes hot, the internal pressure will increase. Furthermore, when the rear arm that swings up and down holds the rear wheel and the breather hole is held on the vehicle body side, repeated bending stress is applied to the breather pipe, making the breather pipe hardened or frozen easily damaged by cold air. There were also problems.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and it is designed to prevent water from entering the case even if the case of the final reduction gear is submerged in water while driving. Furthermore, even if there are temperature changes in the gear, case, or gear oil, the internal pressure of the case can be maintained at approximately atmospheric pressure to prevent damage to the seal part of the case, and it also prevents ice from forming in the breather hole or moisture in the breather pipe from freezing. It also prevents the breather pipe from becoming blocked due to the vertical movement of the rear wheels, reduces the bending stress applied to the breather pipe due to the vertical movement of the rear wheel, and increases the heat retention effect of the breather pipe, increasing the durability of the breather pipe at low temperatures. The purpose of the present invention is to provide a vehicle for running on rough terrain that can improve the performance of vehicles.

(Structure of the Invention) According to the present invention, the object is to provide at least three wheels fitted with ultra-low pressure tires and an engine disposed near the center of the vehicle body, and to provide a vehicle with a rearward position from a pivot axis close to the rear of the engine. The two rear wheels are held by the rear arm that extends and swings up and down.
A gear case that houses the final reduction gear in a shaft drive rough terrain vehicle that transmits engine rotation to the rear wheels via a drive shaft passing through the cylinder of the rear arm and a final reduction gear provided on the rear wheel shaft. A breather pipe, one end of which is connected to the gear case, is guided near the pivot shaft along the pipe through which the drive shaft passes, and raised further upwards to cover the upper part of the engine from above. This is achieved by a vehicle for running on rough terrain, characterized in that the breather pipe is guided into a recess that opens toward the front, and the other end of the breather pipe is opened above a line connecting the upper ends of the front and rear wheels in the recess. The present invention will be explained in detail below based on the illustrated embodiments.

(Embodiment) Fig. 1 is a side view showing an embodiment of the present invention with the left rear wheel removed, Fig. 2 is a plan view of the main parts, and Fig. 3 is the - line in Fig. 2. FIG.

In FIGS. 1 and 2, reference numeral 10 denotes a frame, which includes a steering shaft tube 12, a main tube 14, and a pair of left and right seat pillar tubes 16 (16a, 1
6b), down tube 18 (18a, 18b),
It has a back tube 20 (20a, 20b), a seat rail 22 (22a, 22b), and the like. Seat pillar tube 16 and back tube 20
The lower end of the down tube 18 and the rear end of the down tube 18 are fixed to the bearing sleeve 24 (24a, 24b).

A steering shaft (not shown) is rotatably held in the steering shaft cylinder 12, and upper and lower brackets 26, 28 are fixed to the upper and lower projecting ends of this steering shaft. front fork 30
is fixed. A front wheel 32 is attached to the lower end of the front fork 30. This front wheel 2
2 has wide ultra-low pressure tires. 34 is an engine mounted near the center of the vehicle body between the seat pillar tube 16 and the down tube 18, that is, between the front wheel 32 and the rear wheel 50 described later.

36 is a rear arm, which includes a front cylinder 38 and a rear cylinder 4.
0, and a left cylinder 42 that connects these two cylinders 38 and 40.
and a right cylinder 44. The front cylinder 38 has a pivot shaft 46 (FIG. 3) between the bearing cylinders 24a and 24b.
As a result, the rear arm 36 can swing up and down about the pivot shaft 46.
A rear axle 48 is rotatably held in the rear cylinder 40,
A pair of rear wheels 50 are provided at the left and right projecting ends of the rear axle 48.
(50a, 50b) are fixed. This rear wheel 50 is equipped with a wide ultra-low pressure tire. Reference numeral 52 designates a cushion unit, the front end of which is supported by a bracket 54 fixed to the rear lower surface of the main tube 14. Further, brackets 56 and 58 that protrude diagonally forward and upward are fixed to the rear cylinder 40 of the rear arm 36, and the rear end of the cushion unit 52 is pivoted to the brackets 58.

A liquid-tight gear case 60 is formed at the joint between the rear cylinder 40 and the left cylinder 42 of the rear arm 36.
A large gear 62a and a small gear 62b constituting a final reduction gear 62 are housed in the gear case 60, and these gears 62 are immersed in gear oil contained in the case 60. Large gear 62a
is fixed to the rear axle 48 passing through the case 60. Further, the small gear 62b is connected to a drive shaft 64 (FIG. 1) inserted into the left cylinder 42. The front end of the drive shaft 64 is connected to the bearing sleeves 24a and 2.
4b, and is connected to a universal joint (not shown) located between the two. Therefore, the rotation of the output shaft of the engine 34 is transmitted to the rear wheels 50 via the universal joint, the drive shaft 64, the small gear 62b, the large gear 62a, and the rear axle 48.

A breather pipe 66 forming an air passage is connected to the upper part of the gear case 60 so as to communicate with the inside of the case 60. This breather pipe 66 is guided to the pivot shaft 46 along the left cylinder 42 of the rear arm 36 through which the drive shaft 64 passes, rises upward from there, passes through the left seat pillar tube 16a, and extends upward along the main tube 14. There is. As a result, the atmosphere side opening 66a of the breather pipe 66 is
Line A connecting the upper ends of the front wheel 32 and the rear wheel 50 (Fig. 1)
It will be located higher than the engine 34 and above the engine 34. The opening 66a is oriented downward away from the direction of travel of the vehicle to prevent rainwater from entering the opening 66a during driving in the rain. In FIG. 1, 68 is a fuel tank installed so as to straddle this opening 66a.
8 forms a recess that covers the upper part of the engine 34 from above and opens downward. The breather pipe 66 is located above the line A connecting the upper ends of the front and rear wheels in this recess.
The atmosphere side opening 66a is located. 70 is a rear fender that covers above the left and right rear wheels 50, and 72 is a vertically elongated driver's seat.

As shown in FIG. 3, a tongue-shaped bracket 74 extending rearward is fixed to the rear cylinder 40, and another bracket 76 is attached to sandwich the above-mentioned bracket 56 extending forward and upward and this bracket 74 from above and below. (76a, 76b) are bolted. This bracket 76 is a tongue-shaped bracket 7.
4, and a spherical projection 78 that projects upward is fixed to the end thereof. This protrusion 78
A traction rod 82 of a trailer 80 shown in FIG. 1 is connected to the traction rod 82 of the trailer 80 shown in FIG. That is, as shown in FIG. 3, a hemispherical shell-shaped engagement bowl 84 with an open bottom is fixed to the front end of the traction rod 82, and the engagement bowl 84 is connected to the protrusion 7.
8, the two are connected. Note that the solid line in FIG. 3 shows the state when the vehicle is not being ridden, and in this state, the rear portions of the tongue-shaped brackets 74 and 76 are oriented diagonally downward and rearward. The imaginary line in the figure shows when the driver gets on the vehicle, and at this time the pivot shaft 46 sinks downward together with the frame 10, and the tongue-shaped bracket 74 and the rear part of the bracket 76 are in a substantially horizontal position. Therefore, the driver gets on the trailer 80
When towing the trailer, the trailer traction force acts horizontally on the brackets 74, 76 which are in substantially horizontal positions, and the bending moment applied to the brackets 74, 76 can be suppressed to a minimum.

According to this embodiment, the inside of the gear case 60 is communicated with the atmosphere through the breather pipe 66, so that if the temperature inside the case 60 rises while the vehicle is running, part of the air inside the case 60 will flow through the breather pipe. Air escapes to the atmosphere through the opening 66a of the casing 66, and if the temperature inside the casing 60 falls when the vehicle is left in a stopped state, air enters the casing 60 through the opening 66a and the breather pipe 66. Therefore, the inside of the case 60 is always maintained at approximately atmospheric pressure, and excessive air pressure does not act on the seal portion of the case 60, so that the seal portion is not damaged.
Further, since the opening 66a of the breather pipe 66 is located at a high position, water does not flow into the case 60 from the opening 66a. This type of vehicle sometimes uses the buoyancy of its tires to float on the water surface to cross rivers and swamps, but the wide and thick tires generate sufficient buoyancy. For this reason, the vehicle body has front and rear wheels 32,
50 is completely submerged in water. Since the opening 66a of the breather pipe 66 is located above the line A connecting the upper ends of the front and rear wheels 32 and 50 and above the engine 34,
Even when the entire vehicle floats on the water surface and crosses the water, the opening 66a will not be submerged in the water. Therefore, water does not flow into the case 60 at this time either, and there is no risk of deterioration of the gear oil or adversely affecting the life of the final reduction gear 62.

Further, since the atmosphere-side opening 66a of the breather pipe 66 is located in the downwardly opening recess covering the upper part of the engine, rainwater does not enter the opening 66a and is warmed by the hot air of the engine 34. i.e. engine 3
Since the hot air 4 is trapped in the recess, the inside of the recess is kept warm not only while driving but also for a while after the engine is stopped, and even if ice forms in the opening 66a of the breather pipe 66 while driving, it will evaporate due to the hot air from the engine 34. There is no freezing here. Even if ice should form while driving, the engine heat immediately after the engine stops will melt the ice, so it will not interfere with the breather function. Additionally, even if ice forms while the vehicle is stopped, the heat from the engine can be used to melt the ice while the vehicle is in operation.

On the other hand, the breather pipe 66 is guided to the pivot shaft 46 along the left cylinder 42 of the rear arm 36 through which the drive shaft 64 passes, and rises upward from there. This left cylinder 4
2 is warmed by the bearing portion of the drive shaft 64, the gear case 60, etc. when the vehicle is running, so the breather pipe 66 can be heated. Further, since the pivot shaft 46 is located near the rear of the engine, this region also becomes relatively warm, and the breather pipe 66 that rises upward through this region is also warmed. Therefore, the heat retention of the breather pipe 66 is good. Furthermore, since the breather pipe 66 passes near the pivot shaft 46, the bending angle range of the breather pipe 66 is reduced, and the durability of the breather pipe 66 is improved due to the good heat retention properties of the breather pipe 66.

Although this embodiment applies the present invention to a three-wheeled vehicle, it goes without saying that the present invention also includes applications to four-wheeled vehicles. Further, the breather pipe 66 as an air passage is formed of one pipe in this embodiment, but it may be possible to connect a plurality of pipes or
The seat pillar tube 16, back tube 20, etc. that make up the air passage may be used as part of this air passage.

(Effects of the Invention) As described above, the present invention connects the air passage to the gear case housing the final reduction gear, and connects the upper ends of the front and rear wheels within the recess that opens downward above the engine. Since the atmospheric side opening of this air passage is located above the line, water will not enter the gear case through this opening even if you cross the water while floating. Therefore, deterioration of the gear oil can be prevented and the life of the gear can be extended. Furthermore, since the internal pressure of the gear case is always approximately equal to atmospheric pressure, there is no possibility of damaging the sealing member of the gear case. Because the hot air from the engine accumulates in the recess above the engine, it is difficult for dew to condense on the atmosphere-side opening of the air passage, and ice formation can be prevented. In addition, even if ice forms while the vehicle is running, it will be melted by the heat of the engine immediately after the vehicle stops, so the breather function will not be affected, and even if ice forms while the vehicle is stopped, the heat from the engine during driving will melt the ice.

On the other hand, the breather pipe is guided to the pivot shaft along the cylinder of the rear arm through which the drive shaft passes, and rises upward from there. Since this tube is warmed by the drive shaft bearing and gear case while the vehicle is running, the breather tube is also warmed. Also, since the pivot shaft is located near the rear of the engine, this area also becomes relatively warm, and the breather pipe that rises upward through this area is also warmed. Therefore, the breather pipe retains heat well. Furthermore, since the breather tube passes near the pivot axis, the bending angle range of the breather tube is narrowed, and the durability of the breather tube is improved due to the good heat retention properties of the breather tube.

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment of the present invention with the left rear wheel removed, Fig. 2 is a plan view of the main parts thereof, and Fig. 3 is a sectional view taken along the line - in Fig. 2. . 32... Front wheel, 34... Engine, 50... Rear wheel, 60... Gear case, 62... Final reduction gear,
66... Breather pipe as an air passage, 66a...
...Opening, A...The line that connects the tops of the front and rear wheels.

Claims (1)

[Claims] 1. A vehicle comprising at least three wheels fitted with ultra-low pressure tires and an engine disposed near the center of the vehicle body, extending rearward from a pivot shaft near the rear of the engine and swinging up and down. A shaft drive type rough ground that holds two rear wheels on a moving rear arm and transmits engine rotation to the rear wheels via a drive shaft passing through the cylinder of the rear arm and a final reduction gear installed on the rear wheel shaft. In a traveling vehicle, a gear case housing the final reduction gear is formed to be liquid-tight, and a breather pipe, one end of which is connected to the gear case, is guided along a cylinder through which the drive shaft passes near the pivot axis, and further upward. The breather pipe is raised up and guided into a recess that covers the upper part of the engine from above and opens downward, and the other end of the breather pipe is opened above a line connecting the upper ends of the front and rear wheels in this recess. A vehicle for driving on rough terrain.