Recreational vehicle with air cooled transmission

#The invention relates to motor-powered recreational vehicles, and in particular to the use of air-cooled variable speed transmissions on recreational vehicles.

#Recreactional vehicles such as three-and four-wheeled "all terrain vehicles" ("ATV's") commonly are used on a variety of harsh terrains including sand, gravel, grass, snow, mud, dirt, and even shallow water. The vehicles generally are powered by internal combustion engines linked to the drive wheels by conventional gear trains.

#Variable speed split sheave V-belt clutch transmissions are well known and frequently are used on snowmobiles. These transmissions are desirable for a variety of reasons including their "automatic" nature; i.e., the operator need not shift the transmission through a series of gears because it is automatically continuously variable, and may automatically disengage the drive train by releasing the V-belt during idling (i.e., below a pre-determined RPM).

#FIG. 1 is a side elevational partially broken away view in partial cross-section of the recreation vehicle of the invention;

#FIG. 2 is a cross-sectional plurality broken away view of the recreation vehicle of FIG. 1 taken along line 2--2 thereof;

#FIG. 3 is an elevational view of a pulley sheave of the invention taken along line 3--3 of FIG. 2;

#FIG. 1 shows a representative three-wheeled recreational vehicle having a frame (11) to which are mounted an engine (10) and driven wheels (12) linked to the engine (10) by transmission means (20). The transmission means includes a variable speed, split-sheave V-belt transmission of the type commonly used on snowmobiles. Such a split-sheave variable speed transmissions are well known in the art and need not be described in detail. See, e.g., U.S. Pat. No. 3,733,918, Domass.

#The transmission (20) includes a drive pulley (21), a driven pulley (30), and a endless V-belt (34). Each pulley includes a pair of sheaves, one of which is axially movable. Each sheave has a tapered, V-belt engaging side and a backside facing away from the V-belt. The drive pulley (21) is connected by its drive shaft (22) directly to the engine (10). The pulley (21) is comprised of an inner axially stationary sheave (23) having a plurality of circumferentially open, air-propelling fins (26) on its backside, and an axially movable outer sheave (24) carrying the variable speed mechanism shown generally as (25). Similarly, the driven pulley (30) includes a driven shaft (31), and a pair of sheaves (32) and (33), the inner sheave (32) having a plurality of air-propelling fins (26) on its backside. The driven shaft (31) is mechanically linked to the driven wheels (12); this linkage is not shown for purposes of clarity, but may include a conventional foreward-neutral-reverse gearbox.

#To protect the transmission from water and debris, the transmission (20) is enclosed within a housing (35). The housing (35) has an intake port (36) and exhaust port (37) to facilitate the movement of cooling air through the housing (35). An intake tube (40) and exhaust tube (44) desirably are provided to supply and exhaust air to and from the housing (35).