WO2007079526A1

WO2007079526A1 - Actuator

Info

Publication number: WO2007079526A1
Application number: PCT/AU2007/000006
Authority: WO
Inventors: Andrew Kirsh
Original assignee: Andrew Kirsh
Priority date: 2006-01-09
Filing date: 2007-01-09
Publication date: 2007-07-19

Abstract

An actuator (10) for a fluid dispenser, the actuator including a base (12), a rotor (14) rotatably mounted to the base and a plunger (16) slidably mounted to the base. The plunger and rotor having mutually inter-engageable earning formations (18) arranged such that axial movement of the plunger between a rest position and an actuating position causes rotation of the rotor thereby applying an actuating force to the dispenser.

Description

TITLE: ACTUATOR

TECHNICAL FIELD

The present invention generally relates to actuators and more particularly to actuators used for operating a fluid dispenser.

The invention has been developed primarily as a foot operated actuator for connection to a fluid dispenser and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. BACKGROUND OF THE INVENTION

The following discussion of the prior art is intended to place the invention in an appropriate technical context and enable the associated advantages to be fully understood. However, any discussion of the prior art throughout the specification should not be considered as an admission that such art is widely known or forms part of the common general knowledge in the field.

Before any surgical procedure, surgeons are required to rigorously wash their hands prior to entering a surgical theatre. Typically, this involves dispensing a liquid soap onto their hands from a liquid soap dispenser.

One known device to actuate such a liquid soap dispenser is a foot operated air pedal switch. This device activates a pneumatically operated pump for dispensing the liquid soap upon depressing. It has been found however, that this device does not operate with enough directness to provide a consistent measured amount of liquid soap upon each application. This in turn results in wasted product due to repeated applications. Another known device to actuate a liquid soap dispenser is the mechanical single wedge actuator. This actuator, when depressed moves a cable, which is directly connected to the plunger portion of the dispensing pump thereby to dispense the liquid soap. A disadvantage of this actuator is that it tends to bind or jam when not acted upon by a directly perpendicular force. This again results in an inconsistent amount of liquid soap being dispensed.

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. SUMMARY OF THE INVENTION

According to the invention, there is provided an actuator for a fluid dispenser, the actuator including: a base; a rotor rotatably mounted to the base; and a plunger slidably mounted to the base, the plunger and rotor having mutually inter-engageable earning formations such that axial movement of the plunger between a rest position and an actuating position causes rotation of the rotor thereby to apply an actuating force to the dispenser. In a preferred form, the earning formations include at least one ramp formation on the rotor. Preferably, the earning formations include at least one complementary ramp formation on the plunger camingly engageable with the ramp formation on the rotor. More preferably, the actuator includes a plurality of the ramp formations circumferentially disposed around the rotor. The ramp formations may also be symmetrically diametrically disposed.

The plunger is preferably resiliently biased into the rest position and the rotor is preferably resiliently biased against the rotation caused by the plunger.

The plunger and base preferably include respective mutually inter-engageable axially extending guide formations for guiding the plunger between the rest and actuating positions.

Preferably, the plunger and base include respective mutually inter-engageable snap locking formations for securing the plunger to the base.

Preferably, the rotor includes an anchor for securing the proximal end of a Bowden cable. More preferably, the base includes a stopping recess for holding the proximal end of the sheath of the Bowden cable. Even more preferably, the base includes a void area, adjacent the stopping recess, for the anchor.

Preferably, the base includes a central locating rim for rotatably retaining the rotor to the base. The base may also include a plurality of peripheral retaining lugs for rotatably securing the rotor to the base. Preferably, the plunger includes a plurality of cutouts, each cutout adapted to receive a portion of a corresponding ramp formation when the plunger is in the actuating position. In a preferred form, the base, rotor and plunger are formed from a moulded plastics material. BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a perspective view of an actuator according to the present invention;

Figure 2 is a perspective exploded view of the actuator of Figure 1;

Figure 3 is a further perspective exploded view of the actuator of Figure 1 , showing the underside the plunger;

Figures 4a, 5a and 6a are part cutaway perspective views of the actuator of Figure 1 in various states of operation; and

Figures 4b, 5b and 6b are underside views of the actuator of Figure 1 , each respectively corresponding to the states of operation indicated by Figures 4a, 5a and 6a.

PREFERRED EMBODIMENT OF THE INVENTION

Referring to the accompanying drawings there is provided an actuator 10 for remote actuation of a fluid dispenser (not shown). It is proposed that surgeons use the illustrated actuator for dispensing liquid soap in preparation for surgery. Whilst the actuator will be described with reference to being foot operated, it will be appreciated that it may be operated by any suitable means.

Referring now to Figures 1 to 3, the actuator includes a base 12, a rotor 14 rotatably mounted to the base, and a plunger 16 slidably mounted to the base. The plunger and rotor include a plurality of circumferentially and symmetrically disposed earning formations in the form of ramps 18, which are adapted for mutual inter- engagement upon axial movement of the plunger with respect to the rotor. The arrangement is such that when the plunger is axially moved towards the base between a rest position and an actuating position, the complementary earning interaction between the ramps 18 causes the rotor 14 to incrementally rotate thereby actuating the dispenser.

A bias means acting between the base 12 and the plunger 16 is provided in the form of a helical spring 20 to allow the plunger to return to its rest position in the absence of any applied force. The spring is located around a boss 22, which axially protrudes from the centre of the base, and is used to restrain the spring's radial movement. The rotation of the rotor 14 is also biased by its connection to the fluid dispenser such that it will return to a rest position at the same time as the plunger.

A plurality of cut-outs 24, disposed in the plunger 16, are adapted for receiving a portion of a corresponding ramp 18 when the plunger is its maximum actuating position. In this way, the plunger is permitted to travel a full stroke without interference from the ramps colliding with its inside and, as a consequence, the overall height of the actuator 10 is advantageously minimised.

An integrally formed central locating rim 26 and peripheral retaining lugs 28, both disposed in the base, provide rotational and positional control of the rotor during operation.

As best shown in Figure 3, the plunger 16 includes four axially extending fingers 30, which mutually slidably engage with respective bores 32 located in the base 12 upon assembly, thereby to guide the plunger during the axial movement. The plunger and base also include respective mutually inter-engageable snap locking formations in the form of prongs 34 disposed on the plunger, and shoulder 36 disposed on the base 12 for retaining the plunger to the base. It will be appreciated that the relationship between the distal ends of the prongs 34 and shoulder 36 defines the outermost axial position of the plunger with respect to the base or, in other words, the rest position.

A Bowden cable (not shown) is used for translating the rotational movement of the rotor 16 to the pump portion of the fluid dispenser. To facilitate this, the rotor includes an orthogonally protruding anchor 40, which is connected to the proximal end of the cable. The anchor moves within a clearance void 41 in the base further providing a start and an end point to the rotor rotation.

Access to the anchor is provided by recess 42 located in the underside of the base. Recess 42 includes a stop for holding back the sheaf portion of the cable during use. Moreover, as best shown in Figure 2, the locating rim 26 only extends for 270 degrees around the base 12 with the remaining 90 degrees being allocated for clearance void 41.

It will be appreciated that the magnitude of rotation of the rotor 14 is dependant of several design constraints including but not limited to, the longitudinal length of the prongs 34, the height of boss 22, the height of each ramp formation 18 and the circumferential length of the locating rim 26. Therefore, to adjust the magnitude of the rotor's rotation, all these factors would need to be either scaled up or down accordingly. That said, however, minor adjustments of the magnitude of actuation or, degree of displacement of the Bowden cable, can be achieved by repositioning anchor 40 on the rotor 12 relative to the rotor's radial centre.

Figures 4a, 5a & 6a show perceptive views the actuator 10 with part of the plunger 16 cut away so as to illustrate the relationship between the base, rotor and plunger in various states of operation. Similarly, Figures 4b, 5b & 6b are underside views each respectively corresponding to the positions of operation shown on Figures 4a, 5a & 6a so as to illustrate how anchor 40 moves during operation.

Accordingly, Figures 4a and 4b show the actuator in its rest position. In this configuration, no force has been applied to the plunger 16 and it is fully extended by the action of the spring 20, only restrained by the prongs 34 interaction with shoulder 36. It can be seen that rotor 14 can only rotate in the direction indicated by arrow Rl when any force is applied to the plunger. Further, as can be seen in Figure 4b, upon rotation of the rotor 14, anchor 40 will move along an arcuate path generally indicated by arrow Rl, towards the actuating position 40b.

Figures 5 a and 5b show the actuator 10, with a part axial force F2 applied to the plunger. As can be seen, upon application of force F2, plunger 16 has moved downwardly and due to the earning interaction between the ramps 18, rotor 14 has incrementally rotated to the right. As a consequence, anchor 40 has moved away from its rest position 4OA towards the actuating position 4OB. Of course, if force Fl was removed, both plunger 16 and rotor 12 will return to the rest position due to the action of the spring 20. Figures 6a and 6b show the actuator 10 with a maximum axial force F3 applied to the plunger. As can be seen under these circumstances, the plunger 16 has moved until its underside abuts the top of boss 22, thereby rotating rotor 14 to its maximum position and defining the maximum actuating position. At the same time, anchor 40 has also moved away from rest position 4OA to actuating position 4OB. It should be understood that due to the anchor being fixedly connected to the Bowden cable, rotation of rotor 14 pulls on its inner wire to actuate the fluid dispenser.

In a preferred application, the actuator 10 is located at ground level and the foot of a user applies the axial force. The fluid or soap dispenser may be located remotely from the actuator at a location convenient to the user, typically at hand level. In this way, simply approaching the dispenser and stepping on the actuator, at any angle, dispenses the fluid onto a user's hands. Optionally, to prevent the ingress of dirt and generally reduce wear, the actuator may be housed in a resilient cover (not shown).

It will be appreciated that the illustrated actuator allows a user to easily dispense a fluid, such as soap, from a remotely located fluid dispenser by simply applying a downward force to the plunger. Advantageously, the main components of the actuator are formed from a durable moulded plastic making it strong, light, easy to modify to suit the desired application, inexpensive to manufacture, easily cleaned, not readily susceptible to corrosion and able to be used in sterile environments. Furthermore, due to the provision of multiple ramps, binding or jamming is generally minimised and the actuator is easily activated without having to apply a direct vertical force. It will be understood that a "Bowden cable" is a type of flexible cable used to transmit mechanical force or energy by the movement of an inner cable, having an anchor at each end, (most commonly of steel or stainless steel) relative to a hollow outer cable housing or "sheath". Linear movement of the inner cable is generally used to transmit a pulling force, although for very light applications over shorter distances a push force may also be used.

While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An actuator for a fluid dispenser, said actuator including: a base; a rotor rotatably mounted to said base; and a plunger slidably mounted to said base, said plunger and rotor having mutually inter-engageable earning formations such that axial movement of said plunger between a rest position and an actuating position causes rotation of said rotor thereby to apply an actuating force to said dispenser.

2. An actuator according claim 1, wherein said earning formations include at least one ramp formation on said rotor.

3. An actuator according claim 1 or claim 2, wherein said earning formations include at least one complementary ramp formation on said plunger camingly engageable with said ramp formation on said rotor.

4. An actuator according to any one of claim 2 or claim 3, wherein said actuator includes a plurality of said ramp formations circumferentially disposed about said rotor and said plunger.

5. An actuator according to claim 4, wherein said ramp formations are symmetrically and diametrically disposed.

6. An actuator according to any one of the preceding claims, wherein said plunger is resiliency biased into said rest position.

7. An actuator according to any one of the preceding claims, wherein said rotor is resiliently biased against said rotation caused by said plunger.

8. An actuator according to any one of the preceding claims, wherein said plunger and said base include respective mutually inter-engageable axially extending guide formations for guiding said plunger between said rest and said actuating positions.

9. An actuator according to any one of the preceding claims, wherein said plunger and said base include respective mutually inter-engageable snap locking formations for securing said plunger to said base.

10. An actuator according to any one of the preceding claims, wherein said rotor includes an anchor for securing the proximal end of a Bowden cable.

11. An actuator according to claim 10, wherein said base includes a stopping recess for holding said proximal end of the sheath of said Bowden cable.

12. An actuator according to claim 10, wherein said base includes a clearance void, adjacent said stopping recess, for said anchor.

13. An actuator according to any one of the preceding claims, wherein said base includes a central locating rim for rotatably guiding said rotor within said base.

14. An actuator according to any one of the preceding claims, wherein said base includes a plurality of peripheral retaining lugs for rotatably securing said rotor to said base.

15. An actuator according to any one of the preceding claims, wherein said plunger includes a plurality of cut-outs, each cut-out adapted to receive a portion of a corresponding earning formation when said plunger is in said actuating position.

16. An actuator according to any one of the preceding claims, wherein said base, rotor and plunger are formed from a moulded plastics material.

17. An actuator for a fluid dispenser substantially as herein described with reference to any one of said embodiments of said invention illustrated in said accompanying drawings and/or examples.