1. Field of the Invention
This invention generally relates to reciprocating piston mechanisms and more particularly to reciprocating pistons reciprocated by a cam mounted on a rotary shaft by means of cam rollers which are connected to the pistons.
2. Description of the Prior Art
Many energy transfer apparatuses employing cams and reciprocating pistons have been produced in the past. Conventionally, they have been used in internal combustion engines, compressors, and the like.
For example, one type of reciprocating piston internal combustion engine employing cams for operating pistons, is illustrated in the United States Pat. No. 1,765,713. As disclosed therein, cylinders are arranged radially about a drive shaft. Each piston within a cylinder is attached to a roller which is held in contact with a first cam mounted on the drive shaft. Linkages and a second set of rollers riding on a second cam on the drive shaft hold the rollers attached to the pistons in contact with the first cam so that as the pistons reciprocate, the cam is caused to rotate to in turn rotate the drive shaft. In order to maintain the rollers attached to the piston in contact with the cam, the second cam has a different profile from the first cam. A modification of this type of engine is illustrated in U.S. Pat. No. 1,863,877 in which a spring loaded strap extends over sets of rollers to hold the rollers attached to the pistons in contact with the cam. The cam illustrated in this patent has major and minor diameters which are displaced from one another by less than 90.degree. so that the power and intake strokes of the piston occur over 35.degree. of shaft rotation and the compression and exhaust strokes of the pistons occur over 55.degree. of shaft rotation. In the above-described arrangements, the center of the cam is coincident with the center of the drive shaft. Accordingly these arrangements appear to provide less efficiency over conventional engines having a crank shaft for converting reciprocating motion to rotary motion since intake and power portions of the cycle take place over a smaller percentage of the total cycle than the compression and exhaust portions of the cycle. Furthermore, a complicated arrangement is required for holding the piston mounted rollers in contact with the cam.