Abstract:
A foot actuated pneumatic switch for use in association with food-equipment such as mixer-grinders. The switch includes a u-shaped compressible pedal and a hemispherically shaped rubber actuator. The operator applies pressure to the pedal thereby depressing the actuator and initiating operation of the equipment. The pedal operates by means of a spring-like operation which enables the pedal to return to its static position when the pressure on the pedal is removed.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to pneumatic switches, and more particularly, to a foot actuated pneumatic switch assembly for use in association with food equipment such as mixer-grinders. 
     2. Background Information 
     Foot actuated pneumatic switches are often used in the food equipment industry to obtain precise hands-free operation of the desired food equipment, such as a meat mixer-grinder. A typical switch employs some type of actuator, such as a hollow rubber hemisphere, that effects initiation or termination of operation of the equipment. When depressed, the actuator creates a burst of pressurized air which passes through a hose, tubing or other path to flip a pressure operated switch thereby initiating operation of a piece of equipment. 
     Various configurations of such pneumatic switches are known, but as in any industry improved constructions are continually sought. 
     SUMMARY OF THE INVENTION 
     The invention provides a switch assembly having a compressible pedal and an actuator. The pedal is u-shaped, consisting of a top and bottom plate which are hinged by a rear panel having a curved shape and acting as a leaf spring. The actuator is a hemispherically shaped rubber component designed to produce a burst of air when depressed. The operator steps upon the top plate of the pedal, thereby depressing the actuator causing a burst of air to be delivered to a switch which may, for example, initiate or terminate operation of a piece of equipment. Upon removing the pressure applied to the top plate, the spring-like action of the rear panel pushes the u-shaped pedal back into its original shape thereby allowing the actuator to regain its normal shape. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration in an exploded state of one presently preferred embodiment of a foot actuated pneumatic switch assembly constructed according to the present invention; 
     FIG. 2 is a schematic illustration of the foot actuated pneumatic switch assembly of FIG. 1 in assembled form; and 
     FIG. 3 is a schematic illustration of the rear portion of an actuator and associated tubing of the foot actuated pneumatic switch assembly (strain relief not shown). 
    
    
     DETAILED DESCRIPTION 
     A foot actuated pneumatic switch assembly  32  is shown in FIG. 2, with an exploded view shown in FIG.  1 . The switch assembly includes a compressible pedal member  34  and a switch housing  36 . Compressible pedal member  34  includes an upper plate  38 , a lower plate  40 , and a rear panel  42  connecting the two plates. Rear panel  42  preferably has a curved shape and provides as a leaf spring type action. A side to side width of the real panel  42  is less than a side to side width of the plates  38  and  40  such that the side edges of the rear panel are spaced from the sides  37  of the housing  36 , allowing access to the pedal member  34  interior from the rear of the assembly  32 . Pedal member  34  may be formed as a unitary member in which a sheet metal plate is cut and bent to shape. Alternatively the upper plate  38 , lower plate  40  and rear panel  42  may be initially formed separately and then connected together using, for example, a welding operation. 
     Switch housing  36  is formed by a shaped metal plate having two sides  37  and a closed top  39 , with an open back and front. The bottom of switch housing  36  is partially open due to two protruding lips  44 ,  46  which each have two openings designed to match up with the openings on lower metal plate  40  for securing metal plate  40  in a fixed position within switch housing  36  using fasteners (not shown). By securing lower plate  40  in a fixed position within switch housing  36 , compressible pedal member  34  becomes operable. Applying downward force to the upper plate  38  of compressible pedal member  34  causes upper plate  38  to move downward towards lower plate  40  as real panel  42  bends. When the pressure is removed, the leaf spring action of rear panel  42  pushes upper plate  38  in an upward direction until it stops in its original position. Protrusions  48 ,  50  extend from the inner surfaces housing sides  37  to prevent deformation of compressible pedal  36  by inhibiting excessive upward movement of upper plate  38 . Similar protrusions could also be provided to limit the downward movement of upper plate  38 . 
     In addition to the features described above, switch housing  36  also has an opening  52  located near the bottom portion of one of the sides  37 . This opening  52  receives a protective strain relief member  54  which is manufactured from some rigid material such as plastic and is designed to protect hose  56  from being damaged as it passes from actuator  58  to the exterior of the housing  36 . The burst of pressurized air needed to flip a pressure operated switch is generated by actuator  58  which is positioned in the space between the upper plate  38  and lower plate  40 . 
     The actuator  58  is in the form of a hollow rubber hemisphere having an air outlet  57  (FIG. 3) in the rear portion thereof where hose  56  is connected. When deformed, actuator  58  creates a burst of pressurized air that passes through the air outlet  57  in the back portion of the actuator into hose  56  and ultimately to the pressure operated switch on the desired piece of equipment. Actuator  58  is attached, in a fixed position, to the top portion of lower plate  40  by fasteners  60 ,  62 . From this fixed position within compressible pedal member  34 , actuator  58  can be deformed when downward pressure is applied to upper plate  38 . 
     In sum, the user is able to extend a foot through the open front of switch housing  36  onto compressible pedal member  34  for the purpose of applying downward pressure. This downward pressure causes upper plate  38  to move towards lower plate  40  thereby deforming actuator  58 . Upon deformation, actuator  58  produces a burst of pressurized air which travels through hose  56  and flips the pressure operated switch thereby initiating or terminating operation of the desired piece of equipment. When the downward pressure is removed, the leaf spring operation of rear panel  42  returns upper plate  38  to its original position allowing actuator  58  to regain its initial form of a hollow rubber hemisphere. This process can be executed repeatedly to turn a desired piece of equipment on or off. 
     Support feet  62  may also be connected to the switch housing  36  for supporting the assembly  32  as shown. 
     Although the invention has been described and illustrated in detail it is to be clearly understood that the same is intended by way of illustration and example only and is not intended to be taken by way of limitation. A variety of other modifications which do not depart from the scope and spirit of the invention will be evident to persons of ordinary skill in the art from the disclosure herein. For example, the switch housing may taken on various configurations. Further, the actuator may also take on configurations in addition to that shown. Accordingly, the spirit and scope of the invention are to be limited only by the terms of the appended claims.