ROTARY MOTION

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to mechanisms for converting between rotary and reciprocating rotary motion.

2. Brief Description of the Prior Art

Mechanisms converting the motion of vanes or pistons that reciprocate while rotating to rotary driveshaft motion and vice versa are numerous and well known in the art. A typical use is in a vane engine where each of a pair of concentric vane rotors is connected by a mechanism to an output shaft. The motion of a vane rotor rotating at some constant angular frequency, while simultaneously reciprocating at twice that frequency is converted by the connected mechanism to constant rotation of the output shaft. Mechanisms, able to generate a simple harmonic reciprocating motion component (e.g. U.S. Pat. Nos. 1,330,629, 1,946,136), have few load paths and transmit power through line contacts and therefore limit capacity. Other designs, with the reciprocating component approximating simple harmonic motion (e.g. U.S. Patent No. 1,603,630), have high inertial forces which limit their speed.

OBJECTS AND SUMMARY OF THE

INVENTION The principal object of the present invention is to provide a simple, robust drive mechanism to transform between reciprocating rotary and rotary motion. Another object of the present invention is to provide a commercially feasible drive mechanism for a pump or internal combustion engine of the reciprocating rotating type.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

In accordance with the foregoing objects, a drive mechanism of the present invention comprises a housing, driveshaft, crank linkage, planet, carrier, flywheel, and

timing assembly. Details of lubrication, bearings, fasteners and the like are not discussed as they fall within the scope of competent engineering work.

The driveshaft, joumaled in the housing, carries a flywheel incorporating a ring gear. The carrier is joumaled in the flywheel and carries a planet which engages the ring gear. As the flywheel revolves with the driveshaft the timing assembly turns the carrier which drives the planet around the ring gear causing a point on the planet gear pitch cylinder to execute a reciprocating motion with respect to the flywheel. A crank linkage connects the planet along the reciprocating axis to an assembly revolving with the driveshaft imparting a reciprocating rotating motion to it.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows assembled and exploded views of one embodiment of a drive mechanism incorporating the present invention.

FIG. 2 shows assembled and exploded views of a second embodiment of the present invention adapted to an internal combustion engine design. FIG. 3 shows assembled and exploded views of a third embodiment of a drive mechanism incorporating the present invention using a cam type timing assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 shows a drive mechanism embodying the present invention. The embodiment shown provides a single load path and incorporates a geared timing arrangement.

The driveshaft D is joumaled in bore H-l in the housing H. A flywheel F is affixed to the driveshaft. The flywheel has a bore F-l parallel to the driveshaft incorporating a ring gear F-2. The carrier C is joumaled in the flywheel bore F-l. The carrier has a bore C-1 to accommodate the planet P. The planet shaft P-l is joumaled in the carrier bore C-1 with the planet gear P-2 engaging the ring gear F-2. The pitch diameter of the ring gear is twice that of the planet gear. The carrier incorporates a timing gear C-2 which engages a sun gear H-2, stationary on the housing. The pitch diameter of the sun gear is twice that of the timing gear. As the flywheel revolves with the driveshaft it drives the timing gear against the sun gear

causing the carrier to revolve. The carrier drives the planet around the ring gear causing a point on the planet gear pitch cylinder to execute a reciprocating motion relative to the flywheel. The timing and sun gears are timed so that this reciprocating motion is normal to the line joining the driveshaft and carrier axes. A crankpin P-3, on the planet, has its axis parallel to that of the planet and passing through a point on the planet gear pitch cylinder. A slider S is rotatably mounted on the crankpin and rests in a slot M-l, part of a driven mechanism M coaxial with and pivoted about the driveshaft. The slider imparts a reciprocating rotating motion to the driven mechanism when the driveshaft is turned. Typically, the driven mechanism may be a vane rotor in a vane engine or pump.

Figure 2 shows a pair of drive mechanisms, each with three load paths, in an arrangement of a vane rotor engine.

Drive mechanisms, combined to share the same flywheel and timing mechanism, may be independently timed for individual output phasing, allowing more than one mechanism to be driven.

The use of circular gears results in the reciprocating component of the motion of the driven mechanism being approximately sinusoidal. Pure sinusoidal and other motion profiles are feasible using non-circular gears.

The path of the crankpin P-3 need not be normal to the line joining the driveshaft and carrier axes. For example, if the path is oriented along the line, the pinion may be directly connected to drive a piston in a rotating piston engine.

The crank linkage may incorporate one or more pivoting links rather than a slider.

An alternative timing assembly may be comprised of a cam and roller arrangement as illustrated in FIG. 3 wherein a roller R on a pin PN, affixed to the planet gear pitch cylinder parallel to the crankpin, is guided by a cam CM, affixed to the housing, causing the pin to reciprocate as the drive shaft rotates. In the embodiment shown, two rollers are used with an external cam, with the relative timing of the rollers maintained by the crankarm CA. The crankarm also serves as a connecting link (at CA-1) to the driven mechanism. It will be understood from the examples cited, that the construction and arrangement of the various parts of the invention can be varied without departing from the scope of the invention or from the general mode of operation.

While a certain illustrative embodiment of the present invention has been shown in the drawings and described in considerable detail, there is no intention to limit the invention to the specific forms disclosed. The intention is to cover all modifications, alternative constructions, equivalents and uses falling within the spirit and scope of the invention as expressed in the appended claims.