Microswitch With Improved Flexible Loop Sensing Means For Detecting Transient Objects

Abstract

A commercially available micro switch is provided with a lever clamped at one end. Near the free end and the point of contact with the switch rod, there is mounted an annular loop consisting of a flexible material.

Description

The present invention relates to a pressure-responsive switch whose most practical form is the so-called "Micro Switch" in which the pushbutton or switch rod is operated via a lever carrying an actuating element projecting into the track of an article being moved in relation thereto, and is only supposed to respond to one direction of movement of this article or object. Such a switch, and also the actuating element is required to have a low weight of all moving parts, so that only small masses have to be moved, no impacts are transferred to the switching mechanism, and practically no frictional forces are exerted upon the controlling article or object. Moreover the switch is required to operate reliably and to have a long service life.

The article or object moved in relation to the switch, may be the control element of various arrangements, such as for the measuring and counting of mechanical quantities, but also for controlling the conveying paths in a conveyor system by way of indirect actuation by the conveyor container. The requirement according to which the switch is only supposed to respond to movements in one direction, results from a problem often arising in practice.

In hitherto conventional types of switches the actuating element extending into the track of a moving article or object, is a rod of either a rigid or flexible material.

It has proved, however, that such a switch only insufficiently meets the requirements as placed thereon. In particular, it has been noticed that the actuating element does not release the switching operation reliably in cases where the controlling article or object comes to a standstill over the switch. This disadvantage, however, can be overcome by employing an actuating element which, for example, in the case of a conveying system, extends far enough into the conveying path, but in consequence of this there will appear the disadvantages that the movement of this article or object is either influenced to an inadmissibly strong extent by the actuating element, or that the element is damaged in the case of a movement which is in opposition to the one releasing the switching operation, this having an unfavorable influence upon reliability and service life of the switch, and the switching operation is only released with a certain time delay.

According to the present invention these disadvantages are avoided in that the actuating element is an annular loop. This loop projects in its longitudinal direction into the track of movement. The lever actuating either the pushbutton of the switch or the switch rod, is appropriately fixed in position at one end, and touches this pushbutton with its other free end, with the loop being mounted near this point of contact. The loop itself consists of a light-weight material, i.e., appropriately of a flexible plastics material, such as polyamide.

For explaining the invention, one example of embodiment will now be described with reference to FIGS. 1 to 3 of the accompanying drawings, in which:

FIG. 1 shows the side view of the switch according to the invention,

FIG. 2 shows the switch while being actuated by the controlling article or object coming out of the prescribed direction, and

FIG. 3 shows the switch while being actuated by an article or object coming from the opposite direction.

The micro switch 1 is mounted to a switch wafer 2a which, in turn, is firmly connected to a base plate 2 arranged near a conveying section or path. The switch rod 3 directly acting upon a tilting spring with the moving contact, is positioned near one edge of the switch housing, and is operated by a lever 4 which is firmly attached at the other edge of the housing. To this lever and near its point of contact with the switch rod i.e., at point 7, there is mounted a polyamide loop 5 wherein the mounting is by any suitable means such as bonding with the diameter thereof appropriately amounting to a multiple of the length of the lever 4. As shown in the figures, loop 5 is additionally position-stabilized by way of horizontally arranged pegs 8 mounted in base plate 2 so as to project outward through the interior of the loop 5.

If, as shown in FIG. 2, a pressure is exerted upon the loop 5 by the article or object 6, which also only extends slightly in the direction of movement of the object or article 6, then the lever 4 is moved downwards, thus causing the switch rod 3 to press upon the tilting spring for tripping the switching process or operation. However, if the pressure also only slightly extends in the opposite direction then, as shown in FIG. 3, the lever 4 is lifted and the switch remains unoperated.

Experiments have shown that the loop only needs to project slightly into the track of the moving article or object, e.g., into the travel tube of a pneumatic tube system, for causing the switch to operate in the desired way. There are not transferred any impacts upon the switch, even if the article or object is moved at a very high speed. Service life is particularly long, and reliability is particularly high. The occurring frictional losses are negligibly small.

Claims

What is claimed is:

1. A direction-sensitive pressure-responsive switch arrangement positioned to project into the track of an article being moved relative thereto, and arranged to be responsive to one predetermined direction of movement only of the article, comprising a microswitch having a depressible actuator and a lever arranged to be brought into contact with said depressible actuator, and an annular loop of flexible material arranged to be coupled on one side thereof to said lever and to project via a separate portion thereof remote from said one side into the track, the combined arrangement of said projecting loop and said microswitch relative to said track being such as to cause an article passing in either direction along the track to deform said annular flexible loop accordingly, with the deformation thereof resulting from a passing article in said predetermined direction only causing actuation of said microswitch.

2. The arrangement according to claim 1 wherein said lever is clamped at one end, and touches with its free end the depressible device, and wherein said loop is mounted proximate this point of contact.

3. The arrangement according to claim 2 wherein said loop is constructed of a flexible plastics material, such as polyamide.

4. The arrangement according to claim 2 wherein the diameter of said loop is a multiple of the length of said lever.