GB2267548A

GB2267548A - Actuating mechanism converting rotary to linear movement

Info

Publication number: GB2267548A
Application number: GB9211559A
Authority: GB
Inventors: Bryan Mitchell
Original assignee: Youngflex AG
Current assignee: L&P Swiss Holding GmbH
Priority date: 1992-06-01
Filing date: 1992-06-01
Publication date: 1993-12-08
Also published as: GB9211559D0

Abstract

An actuating mechanism comprises a mounting frame 1 formed by a U-shaped element of pressed sheet metal having a base wall 2 and two side walls 3 and 4 between which extend two parallel bars 5 and 6 the ends of which are rivetted into apertures in the side walls 3 and 4. A first rotary cam element is formed integrally from synthetics plastics material as a hollow shaft 7 passing through a corresponding aperture in the base wall 2 and a radial cam disc 8, one radial surface of which engages against the base wall 2 whilst the other comprises a spiral cam slot 9. A slide block 12, slideably mounted on the bars 5 and 6 has a cam follower 14 engaging in the cam slot 9. A Bowden cable has a ferrule 18 received in a slot 17 of the side wall 3 and its inner core 21 engaged in a recess in the block 12 whereby rotation of the shaft 7 causes actuation of the Bowden cable via the rectilinear movement of the slide block 12. <IMAGE>

Description

ACTUATING MECHANISM This invention concerns an actuating mechanism, and, in particular, an actuating mechanism for converting rotary motion to translatory motion, for example to enable the operation of a Bowden cable mechanism by means of a rotary drive shaft.

Actuating means have hitherto been proposed for coupling a rotary drive shaft to a Bowden cable, usually comprising male and female screw threaded members arranged to be driven to rotate relatively to one another upon actuation of the drive shaft. Since relative movement of the members coupled to the cable normally takes place along an axis that coincides with or is parallel to the axis of the drive shaft, the actuating mechanism requires a relatively large dimension in the direction of the axis of the drive shaft.

Moreover, the attached cable or cables must also extend in a direction parallel to the axis of the drive shaft at the point at which they are coupled to the actuating mechanism.

A device of the above-mentioned construction is disadvantageous, or cannot be used, in applications where there is limited space in the direction of the axis of the drive shaft and it is desirable for the cable or cables to enage with the actuating mechanism in a direction at right angles to the axis of the drive shaft.

It is accordingly an object of the present invention to provide a novel actuating mechanism meeting the above requirements.

In accordance with the invention an actuating mechanism comprises an mounting frame incorporating a linear guide means upon which a slide block is mounted for rectilinear movement, said mounting frame further carrying a rotary shaft to which is fixed a cam disc having a radial face extending in a plane parallel to the axis of said guide means, the said radial face of the cam disc being provided with a spiral cam engaged with a cam follower secured to said slide block, whereby rotary movement of said shaft is effective to move said slide block in a direction at right angles to the axis of the shaft.

An actuating mechanism in accordance with the invention may be utilised for the purpose of actuating one or a plurality of Bowden cables, in which case the outer sheath of the cable may be fastened to the said mounting frame whilst the inner cable is secured to the slide block.

In a particularly advantageous embodiment of the invention a pair of coaxial drive shafts are each coupled to a rotary cam disc, radial faces of the respective cam discs extending parallel to one another on opposite sides of said guide means, and two slide blocks independently movable on said guide means each have a cam follower engaging with a spiral cam provided on the radial face of a corresponding one of the cam discs. Such an arrangement enables two Bowden cables or two sets of Bowden cables to be actuated independently of one another via the coaxial drive shafts, the actuating mechanism being embodied in a compact unit requiring very little space in the direction of the axis of the rotary shafts.

Further preferred features and corresponding advantages of the invention will become apparent from the following description and the accompanying drawings illustrating one example of the invention, in which Figure 1 is an exploded perspective view of an acutating mechanism in accordance with the invention, Figure 2 is a plan view taken on the line II - II of Fig. 1, Figure 3 is a side view of the arrangement of Fig. 1 taken in the direction of the arrow X of Fig. 1, and Figure 4 is a side view of the arrangement of Fig. 1 taken in the direction of the arrow Y of Fig. 1.

Referring to the drawings, an actuating mechanism in accordance with one embodiment of the invention comprises a mounting frame 1 formed by a U-shaped element of pressed sheet metal having a base wall 2 and two side walls 3 and 4 between which extend two parallel bars 5 and 6 the ends of which are rivetted into apertures in the side walls 3 and 4. A first rotary cam element is formed integrally from synthetics plastics material as a hollow shaft 7 passing through a corresponding aperture in the base wall 2 and a radial cam disc 8, one radial surface of which engages against the base wall 2 whilst the other comprises a helical cam slot 9. A second cam element is similarly formed of synthetics plastics material and comprises a rotary shaft 10 that engages within the hollow shaft 7 and a cam disc 11 having, in a radial face that is directed towards the parallel bars 5 and 6, a helical cam slot identical to the cam slot 9 of the radial disc 8.

Two identical side blocks 12 are slideably mounted on the parallel bars 5 and 6 on opposite sides of a common axis 13 of the two shafts 7 and 10, and each have a cam follower 14 engaging in a spiral cam slot of a corresponding one of the discs 8 and 11.

The shaft 10 has an extension lOa that engages in an aperture 15 of a closing plate 16 that is held in place against free ends of the flanges 3 and 4 by means of tongues 3a and 4a thereof that pass through apertures 16a of the closing plate 16 and are then turned over as seen more clearly in Fig. 3, to retain the assembly together as a unit.

Each of the flanges 3 and 4 incorporates slots 17 each of which can receive and retain a ferrule of a Bowden cable, such as that indicated at 18 in Fig. 1. The slide blocks 12 each incorporate slots 19 communicating with cylindrical recesses 20 for engagement with the inner core 21 of a Bowden cable.

It will be appreciated from the above description that an arrangement in accordance with the described embodiment of the invention provides a simple and compact mechanism for the actuation of Bowden cables, each rotary shaft 7 and 10 being capable of transmitting movement via the corresponding slide block 12 to a pair of Bowden cables independently of the operation of the other shaft.

Claims

1. An actuating mechanism comprising an mounting frame incorporating a linear guide means upon which a slide block is mounted for rectilinear movement said mounting frame further carrying a rotary shaft to which is fixed a cam disc having a radial face, the said radial face of the cam disc being provided with a spiral cam engaged with a cam follower secured to said slide block, whereby rotary movement of said shaft is effective to move said slide block in a direction having a component at right angles to the axis of the shaft.

2. An actuating mechanism as claimed in Claim 1, wherein said radial face of the cam disc extends in a plane substantially parallel to the axis of said guide means.

3. An actuating mechanism as claimed in Claim 1 or Claim 2, having a plurality of rotary shafts each coupled to a cam disc and having a slide block cammingly engaged therewith.

4. An actuating mechanism as claimed in Claim 3, having a pair of coaxial drive shafts, the cam discs extending parallel to one another on opposite sides of the guide means and two slide blocks independently movable on said guide means each having a cam follower engaging with a corresponding cam disc.

5. An actuating mechanism as claimed in any preceding claim, wherein a Bowden cable has an outer sheath fastened to the said mounting frame whilst the inner core is secured to a slide block.

6. An actuating mechanism as claimed in Claim 5 as dependent from Claim 4, wherein a pair of Bowden cables are secured one to each slide block.

7. An actuating mechanism as claimed in Claim 5 or Claim 6, wherein the or each slide block incorporates a slot communicating with a recess for engagement with the inner core of the Bowden cable.

8. An actuating mechanism as claimed in Claim 5, Claim 6 or Claim 7, wherein the frame incorporates slots for retaining a ferrule of the Bowden cable.

9. An actuating mechanism as claimed in any preceding claim, wherein said linear guide comprises a pair of parallel spaced apart guide rails.

10. An actuating mechanism substantially as hereinbefore described with reference to the drawings.