Snowmobile Chassis

Abstract

The front end ski post supporting structure is a single piece aluminum casting and the frame is fabricated from welded aluminum extruded and sheet stock. The design is modular in that the same components can be readily modified to make a 15, 18, or 21 inch chassis.

Description

This invention relates to snowmobiles, and more particularly, to improvements in snowmobile chassis frames and front end ski post supports.

Briefly, the invention provides a modular frame and modular front end ski post support which give increased flexibility and economy of manufacture and increased strength and weight reduction.

In the ensuing description the improved snowmobile chassis is described as utilizing aluminum. However, it will be understood that other metals such as lightweight magnesiums are within the scope of the invention and encompassed thereby.

The preferred form of the invention will be described with particular reference to the attached patent drawings in which:

FIG. 1 is a perspective view of the invention;

FIG. 2 is a top plan view;

FIG. 3 is a side elevation view;

FIG. 4 is a rear view;

FIG. 5 is a front view; and

FIG. 6 is a cross-sectional view of one of the side panels.

In the preferred form of the invention the snowmobile chassis comprises a modular frame 10 and a modular front end ski post support 11. Both are constructed from aluminum or other lightweight metals such as magnesium. The modular frame 10 is fabricated from extruded and sheet stock, whereas the modular support 11 is a casting.

In particular, the modular support 11 is a generally U-shaped casting having integral sides 12 and a front facing bite portion 13. The sides 12 are adapted to be connected to the front end of side panels 14 of the modular frame 10 by rivets 15 (see FIG. 3) or the like.

Integral ski post supporting front diverging arms 16 are formed at the corners of the U-shaped casting 11. Their front extremities have integral tubular bearing portions 17 formed therein. As will be obvious to those skilled in the art, the tubular bearings 17 are adapted to receive the posts of not shown front end ski runners of the snowmobile.

Inasmuch as the sides 12 of the casting 11 and the side panels 14 of the frame 10 are connected to each other by rivets 15 or the like, these two parts 12 and 14 reinforce each other. In addition, they have aligned bearing apertures 18 formed therein at each side of the chassis. These bearing apertures 18 are adapted to support the not shown snowmobile belt drive shaft therein.

As heretofore stated the front end ski post support 11 is modular, and this is so since it is conceived and designed so as to be adapted to fit 15, 18, or 21 inch width frames 10. This is accomplishable in the casting by using not shown inserts in the casting mold to selectively increase or decrease the width of the casting so as to match it up with the selected size of the modular frame, as will be more clear hereinafter. Heretofore the front end ski post support was built up from a plurality of pieces of welded or riveted steel stock which was more expensive to fabricate and did not give a modular front end ski post support as in the instant invention, nor the advantage of lighter weight with increased strength, as will be further described hereinafter.

The chassis frame 10 is tunnel shaped and in concept and design comprises a minimum number of separate pieces connected together in such a manner that a modular frame of varying size is readily obtainable. Specifically, there are two extruded lightweight metal side panels 14, a top sheet 19, and a back sheet 20 (see FIG. 4). The top sheet 19 can be of lighter guage than the side panels 14 since it has integral transverse reinforcing corrugations 21 formed therein. The back sheet 20 is connected to both the side panels 14 and the top sheet 19 by rivets 22 (see FIGS. 2 and 3) or the like to reinforce the rear end of the tunnel frame 10.

Two running board sheets 23 are also provided for the frame. These are connected to the lower portions of the side panels 14 by spot welds 24 (see FIG. 2) or the like. The top sheet 19 is connected to the upper portions of the side panels 14 by spot welds 25 (see FIG. 2) or the like.

The snowmobile frame 10 is modular since it can be easily converted to a 15, 18, or 21 inch width tunnel merely by varying the width of the top sheet 19 and back sheet 20. The other parts of the modular frame 10 such as side panels 14 and running boards 23 are constant. In other words, it is very easy to vary the selected width of the chassis and match up the frame 10 and front support 11 with each other. Heretofore, this was not possible to achieve at a low manufacturing cost since the frame was a large single piece steel stamping. The steel stamping was also heavier than the fabricated aluminum or magnesium modular frame of the instant invention, and not as strong, and also required much more storage or inventory space. In the instant invention it is very easy to stock the pieces 14, 19, 20, 23 separately or partially assembled in a smaller area than the prior art frames and then finish the assembly depending on the size chassis desired.

Referring now to FIG. 6 for a more detailed description of the parts, the side panels 14 have inwardly and outwardly directed integral shouldered ledges 26 and 27 formed at the upper and lower portions thereof respectively. The ledges 26 and their shoulders 26' serve to nest the opposite edges of the top sheet 19 to the side panels 14 so they are aligned together for connection together by the welds 25. The running board sheets 23 are similarly aligned with the side panels 14 for connection together by the welds 24. The ledges 27 have end shoulders 27' and in addition, overhanging spaced ledges 28 are integrally formed along the ledges 27. The ledges 27 and 28 are spaced by a distance equivalent to the thickness of the running board sheets 23. The inner edges of the running board sheets are adapted to be nested between the spaced ledges 27 and 28. The outer edges of running board sheets 25 are curled so as not to present a sharp outer edge.

The spot welds 25 and 24 (see FIG. 2) connecting the top sheet 19 and running board sheets 23 to the side panels 14 are formed in the ledges 26 and 27 respectively. The running board sheets 23 also have integral upwardly sloped front foot rest portions 23'. These foot rest portions 23' are also connected to the side panels 14 by spot welds or rivets.

Still referring to FIG. 6, an overhanging shoulder 26" is formed at the upper outer corners of the side panels 14. The shoulders 26" and overhanging ledges 28 serve to nest or align the front casting 11 with respect to the frame 10.

It should be noted that the welding of parts 14, 19, and 23 can be readily accomplished in a welding jig. Also, the parts can be stored partially preassembled. That is to say, the running board sheets 23 can be prewelded to the side panels 14, and different size top sheets 19 prewelded to one of the side panels 14, and then the assembly completed out of inventory depending upon what final tunnel width is desired. Of course, besides varying the width of the chassis, it is also very easy to vary the length by changing the length of the parts 14, 19 and 23.

It was stated previously that the casting sides 12 and side panels 14 reinforce each other, and the same is true of the parts 14, 19 and 20 at the rear end of the tunnel. Also, the corrugations 21 in the top sheet 19 stiffens the same. In addition, the ledges 26-28 stiffen the side panels, and the front casting 11 has webs or flanges to likewise strengthen the same. What all this means is that the invention, besides all the aforementioned advantages, makes it possible to achieve about a 10 percent weight reduction and 10-13 percent increase in strength over prior art comparable frames. This is an important advantage of the invention considering the punishing use to which snowmobiles are sometimes subjected, and that the invention makes it possible to increase the power to weight ratio without increasing engine size. The weight saving in the machine is of the order of 45 pounds. Also, the invention makes it possible to service the machine by readily replacing damaged parts. In the prior art the front end support was a multi-part steel structure welded and/or riveted to the frame in such a manner that it wasn't readily replaceable. Also, the frame was a large single piece steel stamping so that a damaged portion thereof wasn't replaceable nor the undamaged part thereof salvageable. In the invention these disadvantages are overcome since the welded or riveted connections can be readily broken to separate the parts so that the damaged ones can be replaced or the undamaged ones salvaged.

Claims

What I claim to be my invention is:

1. A snowmobile chassis, comprising a modular frame constructed from lightweight extruded and sheet metal stock and a single piece lightweight metal front end modular ski post support, said modular frame comprising a tunnel having two extruded aluminum side panels, a top aluminum sheet joined to the upper portions of said side panels, a pair of aluminum sheets joined to the lower portions of said side panels to provide running boards on said tunnel, said ski post support comprising an integral generally U-shaped aluminum casting having its sides joined to the front ends of said side panels for reinforcing each other, said casting having a pair of integral front diverging ski post supporting arms formed thereon, integral tubular bearings formed in said arms for supporting a pair of ski posts therein, transverse corrugations formed in said top sheet to stiffen the same, and a pair of aligned bearing apertures formed in the portions of the casting sides and side panels which are joined to each other for supporting a snowmobile drive belt shaft therein.

2. In a snowmobile chassis as in claim 1, wherein said modular frame is adapted to have different width top sheets joined to the side panels to vary the width of said tunnel, and said modular ski post support is adapted to fit different size tunnels by varying the cast width of said U-shaped aluminum casting, to match up the front end casting with the tunnel.

3. In a snowmobile chassis as in claim 2, wherein the upper and lower portions of said side panels have inwardly and outwardly directed integral shouldered ledges formed thereon for nesting the opposite edges and inner edges of said top and running board sheets therein, and said ledges and edges being spot welded to each other.

4. In a snowmobile chassis as in claim 3, overhanging shoulders formed on the upper portions of said side panels to align said modular ski post support and frame with each other, and the sides of said aluminum casting and side panels being riveted together.

5. In a snowmobile chassis as in claim 3, integral overhanging ledges formed on the lower portions of said side panels adjacent to the shouldered ledges thereof, said overhanging and shouldered ledges being spaced from each other by a distance equivalent to the thickness of the running board sheets, and the inner edges of said running board sheets being nested between said spaced overhanging and shouldered ledges.

6. In a snowmobile chassis as in claim 3, a pair of integral upwardly slanted foot rests formed on the front ends of said running board sheets, said foot rests being joined to said side panels, and a back panel at the rear end of said tunnel, said back panel being joined to said side panels and top sheet to reinforce the rear end of said tunnel.

7. A snowmobile chassis modular frame constructed from lightweight extruded and sheet metal stock, said modular frame comprising a tunnel having two extruded aluminum side panels, a top aluminum sheet joined to the upper portions of said side panels, a pair of aluminum sheets joined to the lower portions of said side panels to provide running boards on said tunnel, transverse corrugations formed in said top sheet to stiffen the same, and said modular frame being adapted to have different width top sheets joined to the side panels to very the width of said tunnel.

8. In a snowmobile chassis modular frame as in claim 7, wherein the upper and lower portions of said side panels have inwardly and outwardly directed integral shouldered ledges form thereon for nesting the opposite edges and inner edges of said top and running board sheets therein, and said ledges and edges being spot welded to each other.

9. In a snowmobile chassis modular frame as in claim 8, integral overhanging ledges formed on the lower portions of said side panels adjacent to the shouldered ledges thereof, said overhanging and shouldered ledges being spaced from each other by a distance equivalent to the thickness of the running board sheets, and the inner edges of said running board sheets being nested between said spaced overhanging and shouldered ledges.

10. In a snowmobile chassis modular frame as in claim 9, a pair of integral upwardly slanted foot rests formed on the front ends of said running board sheets, said foot rests being joined to said side panels, and a back panel at the rear end of said tunnel, said back panel being joined to said side panels and top sheet to reinforce the rear end of said tunnel.

11. A snowmobile chassis single piece lightweight metal front end modular ski post support, said ski post support comprising an integral generally U-shaped aluminum casting, said casting having a pair of integral front diverging ski post supporting arms formed thereon, integral tubular bearings formed in said arms for supporting a pair of ski posts therein, a pair of aligned bearing apertures formed in the sides of U-shaped casting for supporting a snowmobile drive belt shaft therein, and said modular ski post support being adapted to fit different size snowmobile chassis frame tunnels by varying the cast width of said U-shaped aluminum casting, to match up the front end casting with the tunnel.