A MECHANISM FOR THE TRANSMISSION OF RECIPROCATING MOTION OF VARIABLE AMPLITUDE INTO UNIDIRECTIONAL CIRCULAR MOTION This invention relates to a mechanism for the transmission of linear reciprocating motion of variable amplitude, or of circular reciprocating motion on one axis into circular unidirectional motion on a perpendicular axis, utilising a flexible member such as a wire.
There are a number of mechanisms for ti transrnission of linear, or semi-hnear reciprocating motion, to circular motion utilising gears or belts. There are several problems related to such existing mechanisms. The most important problem is that the work being done follows a sinusoidal pattern due to the fact that in most applications the driving force cannot always and continuously be tangential to the circle of rotation In order to maximise the rate of producing work many applications limit the displacement angle in a reciprocating motion. What is more, in most existing mechanisms work is produced during half-the cycle whereas the other half (return) is usually not producing work. Induced vibration is also a common problem in existing systems.
It is. an object of the present invention to provide a means of utilising reciprocating linear motion of random amplitude to produce continuous circular motion where work can be produced in both forward and reverse direction of the driving force gaining maximum torque from the application of the driving force and therefore gaining the maximum possible rate of work production.
Another object of the present invention is to provide a means of utilising reciprocating linear motion of random amplitude to produce continuous circular motion such, that fnctional and other energy losses are minimal and there is no induced vibration.
Still. another objective of the present invention_ is to provide a means of utilising reciprocating linear motion of random amplitude to produce continuous circular motion which can consist of simple, readily available parts, and can be manufactured at very low cost.
Still another objective of the present invention is. to provide a means. of utilising reciprocating linear motion of random amplitude to produce continuous circular motion such it is possible that the desired revs of the load can be stepped up or stepped down in a simple manner and without the use of several gears.
According to the present invention there is provided a mechanism for the transmission. of linear reciprocating motion of variable amplitude, into circular motion utilising a . flexible member such as a wire to transmit the motion, and comprising of three threaded drums, two of which are mounted along the same axis which transfers motion to the load. Of the two said drums which are mounted along the same axis which transfers motion to the load, one has a left-hand thread and the other has a right hand- thread and are mounted on the load axis through roller clutch bearings so that motion is continuously transferred to the load both during forward movement of the driving force and during reverse movement (return) of the driving force. A third threaded drum serves as a guide drum to change the direction of the cable, it's length. is longer than the length of the. length of the two other drums together, and it's axis is parallel to the axis upon which the two other drums are mounted and which is the axis along which the load is being driven.
The invention finds applications in several areas in both human powered systems, and in machine powered systems.
A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which : Figure J shows schematically the application of force and torque by use of this invention and by other existing mechanisms Figure 1 shows in perspective a simple implementation of the invention . Referring to Figure 1, the mechanism consists of three threaded drums which are driven by a wire (5). One large threaded drum (6) acts as a guide drum for the wire.
Threaded drums (3) and (4) are mounted on clutch. roller bearings (2). such. as to transmit motion on the load axis (1) in the same angular direction regardless of the direction of the motion of the pulley (6). The two said threaded drums (3 &4) have left hand and right hand threads respectively so that the travel of the threads of the wire on the drums, travels transversely in the same direction so that the ends of the wire on the guide drum (6) do not converge or diverge and jump any threads. For the same reason it is also necessary that all three drums have the same pitch of threads. The large threaded drum (1) is mounted on normal roller bearings for free rotation. The driving force could be coupled either on the pulley (6) or by means. of direct coupling. on the wire (5) at say point A, so that there can be linear movement of the driving force between points A and B, as illustrated. The pulley (6) or another fourth axis can be used to complete the wire loop and can he. implemented m a variety of ways to transmit either linear motion or circular motion. The distance between, the load axis and the pulley (6) can be adjusted according to the maximum amplitude of the linear motion of the driving force and to the geometry restrictions of the exact application.
The diameter of the drums can be selected as appropriate in order to get the revs of the load axis as close to the desired revs as possible, according to the speed of the linear motion of the driving force. It is also possible that the two threaded drums on the load axis (3&4) are constructed as cones with appropriate control mechanism to provide for a smooth stepping up or stepping down of the revs of the load without involving. any complex gears.
It is possible that the threaded drums are manufactured to be oval or other non- cylindrical shape in order to serve specific needs for a desired pattern of non- symmetric acceleration of the load or to serve specific patterns of magnitude of torque at a certain position of the cycle of the driving force.
The design of mechanism provides the possibility to connect several systems in parallel, all mounted on the load axis, without any need to be in sync, thus allowing several driving forces to operate independently, on the same load