Three-point engine mount

An engine mount system for connecting an engine to a chassis, includes a mounting plate and first, second and third engine mounts. The first engine mount secures a first engine side to a first side of the chassis. The second and third engine mounts secure the mounting plate to the chassis. The mounting plate is also secured to a second side of the engine and is configured to mount a drive shaft of the engine and a driven shaft of a vehicle transmission system.

BACKGROUND OF THE INVENTION

This invention relates to an engine mount system for a straddle-mounted vehicle. More particularly, the invention relates to an engine mount system for a snowmobile that connects the engine to the chassis at three locations.

Snowmobiles are a widely used means of transportation in snowy regions. They are especially popular for recreational purposes such as trail riding or racing. V-belt type continuously variable transmissions are typically used in snowmobiles to transfer power from an engine to a drive track. Variable transmissions include a drive shaft with an attached drive clutch and a driven shaft with an attached driven clutch.

In a typical arrangement, multiple engine mounts connect the engine to the chassis, and the drive shaft and the driven shaft are separately connected to the snowmobile chassis. A shortcoming of this arrangement is that it allows “play” between the engine and the variable transmission. Play in the system directly affects the engine's ability to transfer power to the transmission, especially under heavy loads such as during acceleration, and contributes to additional vehicle vibrations.

An improved system that decreases vibrations and reduces play between the snowmobile engine and the variable transmission would be advantageous for improving acceleration and efficient power transfer and reducing vehicle vibrations.

SUMMARY OF THE INVENTION

Generally, the present invention relates to engine mount systems for mounting an engine to a vehicle chassis. One embodiment of an engine mount system for connecting an engine to a chassis includes a mounting plate and first, second and third engine mounts. The first engine mount secures a first engine side to a first side of the chassis. The second and third engine mounts secure the mounting plate to the chassis. The mounting plate is also secured to a second side of the engine and is configured to mount a drive shaft of the engine and a driven shaft of a vehicle power transmission system.

A method of mounting an engine to a chassis includes securing a first engine side to a first chassis side with a first engine mount and securing a mounting plate to the chassis with second and third engine mounts. The method also includes securing an engine second side to the mounting plate and mounting a drive shaft of the engine and a driven shaft of a vehicle power transmission system to the mounting plate.

The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. The Figures and the detailed description that follow more particularly exemplify these embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention relates to an engine mount device for a straddle-mounted vehicle. The invention relates particularly to a snowmobile where the engine mount device mounts an engine to a chassis using three engine mounts. Furthermore, the engine drive and driven shafts are connected to the chassis through a common mounting device. The embodiments, as hereinafter detailed, should not be interpreted as limiting the breadth of potential uses in other vehicles or in other commercial fields of endeavor for other intended purposes.

The prior art teaches an engine10mounted to a chassis12at multiple locations such as with engine mounts14,15,16, and18shown inFIG. 1. A drive shaft20extends from one side of engine10and separately connects to chassis12at a shaft mount22. A driven shaft24is also connected to chassis12at a shaft mount26. Power is transferred from engine12through drive shaft20to driven shaft24via a drive belt28that extends between a drive clutch30secured to drive shaft20, and a driven clutch32secured to driven shaft24.

According to this and other engine mounting arrangements taught in the art, a measurable amount of play exists between the drive and driven shafts when operating the vehicle. This “play” is due, in part, to the drive shaft and the driven shaft being mounted separately to the chassis. As the chassis vibrates, expands, contracts and is otherwise distorted during vehicle use, the distance and relationship between the drive and driven shafts may vary, causing increased vibrations in the system and a reduction in power transfer from the drive to the driven shaft.

Another shortcoming of the prior art is related to engine mounts14,15,16and18. The engine mounts of the prior art fail to adequately provide shock absorption of forces generated between the engine and the chassis during vehicle use. The present invention, as disclosed herein and illustrated inFIGS. 2–5, addresses these deficiencies.

Throughout the remainder of this detailed description, common features as those shown inFIG. 1will be referenced with the same or similar reference numerals in order to clarify the description of the drawings.

On embodiment of the present invention includes an engine mount system100for mounting an engine to a chassis of a vehicle. System100includes a mounting plate140and engine mounts160,162and164, as shown inFIG. 2. Mounting plate140includes a first shaft mount aperture148for receiving a drive shaft from the engine, and a second shaft mount aperture150for receiving a driven shaft of the power transmission system of the vehicle. Further, holes152and slots154are formed in the mounting plate for the purpose of securing the engine to mounting plate140. Apertures161,163, and165are associated with each of the engine mounts160,162and164, respectively. Greater detail concerning mounting plate140is discussed with reference toFIGS. 4 and 5.

The engine mount system100attaches the engine to the chassis at three locations, preferably at opposing sides of the engine. It is advantageous to attach an engine to a chassis at opposing sides of the chassis for the purposes of stability and reduction of vibrations. The position of engine mounts160,162and164on chassis112represent advantageous mounting locations for the embodiment shown and described inFIGS. 2 and 3. However, the placement of engine mounts on a chassis may vary widely according to the design and application of the vehicle and its associated engine mount system. According to engine mount system100, a single engine mount160is placed on a side of chassis112opposite the side of the chassis where engine mounts162and164are located. Two engine mounts162and164are used in this embodiment in part for the purpose of providing additional engine stability on the side of the engine where the drive shaft functions. Engine mounts162and164are also used for the purpose of providing a stable connection of mounting plate140to chassis112. Engine mount164is positioned on mounting plate140at the particular location illustrated inFIG. 2to provide a connecting point for mounting plate140to the chassis between the drive and driven shaft mount apertures148and150. Furthermore, engine mounts162and164are positioned on mounting plate140at the location shown inFIG. 2in part because of the design and shape of chassis112.

Engine mounts162and164may also function to isolate mounting plate140from chassis112. The term “isolation” as used herein may include physical separation as well as providing suspension or shock absorption between two parts. As applied to the present invention, isolation between mounting plate140and chassis112may be accomplished by an engine mount, such as engine mounts162and164, that provides physical separation and suspension between the mounting plate and the chassis.

Engine mount system100is further illustrated in the partial top perspective view ofFIG. 3.FIG. 3illustrates an engine110mounted in chassis112and connected to mounting plate140. Engine mounts162and164mount the mounting plate140to chassis112. The first shaft mount aperture148(not shown) receives a drive shaft (not shown). A drive clutch130is attached to the drive shaft. The second shaft mount aperture150receives a driven shaft124of the vehicle's power transmission system. When the power transmission system is completely assembled, a driven clutch is attached to driven shaft124. Engine110is secured to mounting plate140with fasteners that extend through apertures152and154in mounting plate140. Engine mount160(not shown inFIG. 3) also secures engine110to chassis112.

FIG. 4is a front view of mounting plate140of the embodiment illustrated inFIGS. 2 and 3. Mounting plate140includes first and second shaft mount apertures148and150, fastener apertures152and154, and engine mount apertures163and165. Mounting plate140also includes recessed areas156around a periphery of the mounting plate as well as angled portions170,172and174that help define the shape of mounting plate140.

The size and shape of mounting plate140, and the many apertures formed within are specifically designed for this embodiment of the invention. However, many different shapes and sizes of the mounting plate itself and the apertures formed within it are possible. The invention should be interpreted to include all shapes and sizes of mounting plate140, and the apertures formed within it, as well as the position of the mounting plate on a vehicle chassis.

The shape of mounting plate140, as illustrated inFIGS. 2-5, was derived in large part to be compatible with the chassis design to which it is mounted. A further design consideration for mounting plate140is the need for weight reduction of all components of the vehicle. Thus, mounting plate140includes angles portions170,172and174as a result of reducing the size of the plate to its minimum without compromising the structural integrity of the plate.

Structural integrity of mounting plate140must also be considered when forming apertures in the plate. For example, engine mount aperture163and second shaft mount aperture150would optimally be placed at the very far extremes of mounting plate140, or in other words at its end surface. However, a certain amount of material must be present between the absolute end surface of the plate and the aperture in the plate so that the engine mount or shaft for which the mounting plate is secured to will have sufficient mounting plate surface area to interface with in order to fulfill that feature's intended purpose without the mounting plate failing. Thus, as used throughout the application, when a feature is described as being at “an end” or a “side” of mounting plate140, it is intended that the feature is spaced a sufficient distance from that end or side surface to provide for the necessary structural integrity to be maintained.

As viewed inFIGS. 2 and 4, fastener apertures152and154are arranged for receiving fasteners to fasten mounting plate140to engine110. These apertures may be formed in plate140in a variety of arrangements and sizes. In the engine mount system illustrated inFIGS. 2–4, apertures152and154are arranged near or around first shaft mount aperture148. This type of arrangement provides for an easy way to mount engine110to mounting plate140at a location near drive shaft120, which is extending from the engine through the mounting plate.

The engine mounts160,162and164, illustrated inFIG. 2, are configured in a way to provide optimum shock absorption as well as providing a secure connection of the engine to a vehicle chassis. A front view of an engine mount160is illustrated inFIG. 5. The engine mount includes shock absorbing material180and fastener components182and184. Shock absorbing material180may be rubber or another material having properties of high shock absorption and durability. Fastener component182is shaped so that there is more shock absorbing material vertically between the fastener component182and an outer surface181of the engine mount than the amount of material horizontally between component182and outer surface181of the engine mount. The shape and size of component182may vary so long as there is more shock absorbing material vertically than there is horizontally within the engine mount.FIG. 6illustrates an alternative fastener component282that engages shock absorbing material280and is mounted to chassis112with a fastener component184.

Fastener component184is used in part to connect the engine mount to the chassis or mounting plate to which it is attached. Fastener components182and184may be separate components or may be formed into the same component.FIG. 7is a cross-sectional view of the engine mount ofFIG. 5illustrating fastener components182and184as separately formed where fastener component184is a bolt with a thread shaft portion185and a head portion186. Fastener component182may have a variety of different shapes, such as, for example, a rhombus, oval, circle, triangle, rectangle, or the like shape.

Engine mounts160,162and164are configured to provide additional shock absorption in the vertical direction because of the greater frequency and magnitude of forces acting in the vertical direction in a typical vehicle as compared to the forces in the horizontal direction. However, in alternative embodiments, the engine mounts may be configured to provide maximum shock absorption in the horizontal direction rather than the vertical direction, equal amounts of shock absorption in all directions, or greater shock absorption in the vertical direction as shown and illustrated inFIGS. 2–7. The shock absorbing material180may be configured in a circular shape or in a shape different from a circle, for example, an oval, rectangle, rhombus, triangle, or the like, so long as the engine mount provides the intended shock absorbing function for that particular embodiment.

Alternative engine mount embodiments may include additional fastener components or combinations of two or more shock absorbing materials or pieces of shock absorbing material. The shape of the fastener components may also vary depending on the requirements of the application to which the engine mount is applied. For example, the component182may be positioned in the engine mount so that there is more shock absorbing material horizontally between fastener component182and an outer surface181of the engine mount than the amount of material vertically between component182and outer surface181. This configuration may be particularly useful in an application where the size or frequency of forces in the horizontal direction is greater than those forces in the vertical direction.

Mounting plate140is intended to mount both a drive shaft and a driven shaft. Mounting both shafts to the same plate provides advantages over the prior art because the shape of the mounting plate and the distance between shaft apertures163and165fixes the distance between the shafts. A mounting system with a fixed distance between the shafts reduces the amount of play in the system that is inherent in an engine mounting system that mounts the shafts separately to the chassis. Reduction in the amount of play contributes significantly to a reduction in vibrations as well as increased efficiency in transferring power and torque from the drive shaft to the driven shaft and vice versa.

In a further alternative embodiment of the present invention, mounting plate140and engine110may be secured to chassis112by conventional means, for example, by fasteners rather than by engine mounts with suspension features. However, due to the configuration of mounting plate140, a measurable decrease in vehicle vibrations and an increase in power transfer efficiency may be attained because the drive and driven shafts are fixed a predetermined distance apart by the mounting plate.