Pumps – Motor driven – Electric or magnetic motor
Patent
1990-08-31
1991-07-02
Smith, Leonard E.
Pumps
Motor driven
Electric or magnetic motor
92 33, 74 8915, F04B 3504, F01B 308, F16H 2902
Patent
active
050282174
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for converting a rotational movement into a reciprocating lifting movement or vice versa.
A known apparatus of this kind (U.S. Pat. No. 2,246,733) can be used for controlling valves, robots, machien tools, or the like, and so as to avoid having to use crank-type drives in conjunction with pumps, internal-combustion engines, and the like. In these drives, each force-transfer system consists of individual drive balls that are arranged in part within the bearing drilling and are supported in part in the first and second guide grooves. For this reason, either the wall sections taht incorporate the bearing drillings must be comparatively thin or the diameter of the driver balls must be comparatively large in order that said drive balls can protrude to a sufficient depth into the first and second guide grooves, which leads to unfavourable mechanical/design conditions. Above all, however, because of the fact that the driver balls interact with both guide grooves by sliding friction, an apparatus of this kind is of only limited use and is distinguished by large frictional forces and a high degree of wear.
SUMMARY OF THE INVENTION
It is an object of the present invention to improve the apparatus described such that more favourable mechanical/design conditions result an that during operation there is a considerable reduction of frictional forces and wear.
According to the present invention there is provided an apparatus for converting rotational movement into reciprocating lifting movement or vice versa, comprising a bearing body incorporating a first, cylindrical wall section with first guide grooves that extend in the direction of the lifting movement; a rotary element supported on the bearing body so as to be able to rotate and incorporating a second cylindrical wall section with second guide grooves that are arranged at an angle to the first guide grooves; a lifting element that is supported on the bearing body so as to move back and forth and which incorporates a third wall section that protrudes between the first and the second wall sections, in which continuous bearing drillings with axes that are transverse to the lifting movement are arranged; and a force transfer system with driver balls that are guided within the bearing drillings and supported in part in the first and second guide grooves, wherein in each bearing drilling there are two driver balls that lie one behind the other in the axial direction and which rest against each other, one such driver ball being supported in part in the first guide groove and the other being supported in part in the second guide groove.
The present invention has the important advantage that even the replacement of each driver ball by a pair of driver balls has a considerable effect on the force-transfer process. Since the two driver balls are loaded in opposite directions of rotation during operation, they can roll both in the guide grooves and at their contact points without any significant wear. However, should a slight amount of wear take place because of directions of rotation that are not precisely antiparallel, this can be accepted because the point contact of the driver balls is always on various parts of the ball surfaces as a result of their constant rotation and for this reason cannot lead to a single point of wear on the surface of the driver ball. Finally, a particular advantage lies in the fact that the force components exerted parallel to the axis of the bearing drilling onto the driver balls during the transfer of force can be largely balanced out and for this reason is not transferred to the lifting element, which means that the forces that have to be used to move the lifting element and the rotating element are slight.
In accordance with another feature of the present invention, the drive balls can rest at least when in operation in a central part of the bearing drilling.
In the bearing boring, between the two driver balls, an even number of transmission mechanisms lying one beh
REFERENCES:
patent: 2246733 (1941-06-01), Kiefer
patent: 2321828 (1943-06-01), Lane
patent: 4417860 (1983-11-01), Justice
patent: 4603616 (1986-08-01), Zajac
Freay, Jr. Charles G.
Smith Leonard E.
Striker Michael J.
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