Snowmobile four-cycle engine arrangement

Details Snowmobile four-cycle engine arrangement Snowmobile four-cycle engine arrangement

2001-08-10

2003-05-13

Zeender, F. (Department: 3627)

Motor vehicles

Including one or more ski-like or runner members

With at least one surface-engaging propulsion element

C180S191000, C180S009100, C180S009250, C180S069240, C180S291000, C123S1960CP

Reexamination Certificate

active

06561297

ABSTRACT:

BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an engine arrangement, and in particular relates to an arrangement of a four-cycle engine mounted on a snowmobile.
(2) Description of the Prior Art
Conventionally, small snow vehicles such as snowmobiles have mainly used two-cycle engines. A two-cycle engine is characterized by a relatively simple engine configuration having the advantages of being lightweight and compact and still providing high power. However, two-cycle engines have drawbacks, when compared with four-cycle engines, of emitting a greater amount of exhaust and louder noise with greater vibrations.
The recent worldwide trend demands a silent, clean and environment-conscious engine. Snow vehicle engines are no exception and clean and silent engines have been desired. To fulfil this demand, development of engines for snowmobile into a four-cycle configuration has been studied.
As shown in
FIG. 1
, a typical conventional snowmobile
200
has a body frame
210
in a monocoque frame configuration, wherein an engine
202
is mounted in a space formed between a track housing
211
c
and a front suspension housing
211
b
in the front frame (engine mounting frame)
211
. For a two-cycle engine, engine
202
is mounted upright in an engine compartment
206
.
If a four-cycle engine is attempted to be put into use for a snowmobile in the same manner as above, the upright mounting has been difficult because a four-cycle engine has a greater full height compared to a two cycle engine due to its bulky cylinder head and the necessity of an oil pan. Further, since a four-cycle engine needs additional parts unique to it such as an alternator, supercharger, intercooler, oil filter and the like, it has been very difficult to lay out all these parts in a limited engine compartment space.
To overcome the above space difficulty, there has been a layout proposal as shown in
FIG. 2
in that an engine
202
to be mounted on a snowmobile
201
is set inclined forwards in an engine compartment
206
so as to reduce the full height of engine
202
while the aforementioned components are laid out in the space created by the inclined arrangement of the engine.
On the other hand, in order to enhance the power of a four-cycle engine which is relatively low in power compared to a two-cycle engine, it is generally known that a supercharger(so-called turbocharger) is provided on the intake side of the engine so as to increase the amounts of air and fuel to be supplied to the combustion chamber, to thereby enhance the engine power.
When the engine has a supercharger, provision of an intercooler in the intake line is effective in improving the intake efficiency. However, the position at which the intercooler is attached needs careful thought as to the cooling efficiency of the engine and is affected by the attached position of the supercharger, so that it has been very difficult to design the layout and allot mounting spaces for these components in the engine compartment.
For example, when the intercooler is arranged on the top of the engine, the full height of the engine becomes high so that the center of gravity as well as the body height of the snowmobile becomes high, hence the result is not preferable.
On the other hand, when the intercooler is arranged in front of the engine, the heavy part is located away from the center of gravity, so that the maneuverability lowers. Further, there is another drawback in that if the snowmobile is collided, the front part of the engine compartment will crush so that damage to the engine will become serious.
For a four-cycle engine, the oil pan, designated at
238
, needs to be positioned at the engine bottom. If the engine is of a wet sump type, a large oil pan
238
is needed, which will cause difficulty of interference with the steering shaft, designated at
224
, as shown in FIG.
2
.
Further, for a snowmobile, the underside of the engine compartment serves as a sled sliding over snow, hence needs to be closed, which makes maintenance work such as changing oil difficult.
Moreover, when a four-cycle engine with a V-belt type automatic transmission is used for a snowmobile, the engine is used at higher speeds compared to that of a four-wheel vehicle. Therefore, the engine oil increases in temperature due to increased amount of heat from the engine, whereby oil film starvation may occur, leading to damage to the engine.
SUMMARY OF THE INVENTION
The present invention has been devised in view of the above conventional difficulties, it is therefore an object of the present invention to provide a snowmobile four-cycle engine arrangement with which space saving in the engine compartment is achieved and the workability of maintenance is improved. It is another object of the present invention to provide a snowmobile four-cycle engine arrangement with which cooling performance of the air and engine oil supplied to the engine is improved and space saving is achieved without any loss of maneuverability.
In order to achieve the above object, the present invention is configured as follows:
In accordance with the first aspect of the present invention, a snowmobile four-cycle engine arrangement includes: a four-cycle engine arranged in an engine compartment formed in the front body of a snowmobile with its crankshaft laid substantially parallel to the body width and having a cylinder portion inclined forwards with respect to the vehicle's direction of travel, the engine employing a dry sump oil supplying system; and an oil tank provided in the engine compartment, separately from the engine.
In accordance with the second aspect of the present invention, the snowmobile four-cycle engine arrangement having the above first feature is characterized in that the oil tank is arranged in front of the engine and on the top of a front suspension housing which is projected upwards from the bottom of the engine compartment.
In accordance with the third aspect of the present invention, the snowmobile four-cycle engine arrangement having the above first feature is characterized in that the oil tank is arranged in the rear of the engine and on the upper face of a track housing which is projected upwards from the bottom of the engine compartment.
In accordance with the fourth aspect of the present invention, the snowmobile four-cycle engine arrangement having the above second feature is characterized in that the oil tank is arranged in the rear of the engine and on the upper face of a track housing which is projected upwards from the bottom of the engine compartment.
In accordance with the fifth aspect of the present invention, the snowmobile four-cycle engine arrangement having the above first feature is characterized in that the engine compartment has an opening port with a mating openable and closable lid element, at its bottom for creating communication between the inside of the engine compartment and the external space, at a position opposing the bottom of the oil pan of the engine.
In accordance with the sixth aspect of the present invention, the snowmobile four-cycle engine arrangement having the above second feature is characterized in that the engine compartment has an opening port with a mating openable and closable lid element, at its bottom for creating communication between the inside of the engine compartment and the external space, at a position opposing the bottom of the oil pan of the engine.
In accordance with the seventh aspect of the present invention, the snowmobile four-cycle engine arrangement having the above third feature is characterized in that the engine compartment has an opening port with a mating openable and closable lid element, at its bottom for creating communication between the inside of the engine compartment and the external space, at a position opposing the bottom of the oil pan of the engine.
In accordance with the eighth aspect of the present invention, the snowmobile four-cycle engine arrangement having the above fourth feature is characterized in that the engine compartment has an opening port with a

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