US3440374A - Fluid pressure operated switch - Google Patents

Description

April 22, 1969 G. WINTRISS FLUID PRESSURE OPERATED SWITCH Filed Oct. 18, 1966 VENTOR ATTORNEYS.

United States Patent Oflice 3,440,374 Patented Apr. 22, 1969 U.S. Cl. 200-81 7 Claims ABSTRACT OF THE DISCLOSURE The flow responsive switch disclosed herein has a pressure chamber closed at one end by a diaphragm to which a movable contact of the switch is connected. A snap action is obtained by a magnet armature attached to the diaphragm and movable toward and from a magnet located at a relatively fixed position. A pressure chamber under the diaphragm connects with a passage through which fluid flows and the pressure of fluid in the passage varies in accordance with deflection of the flow at a passage discharge. The preferred embodiment has an aspirator in the flow passage at a location which creates a partial vacuum in the present chamber and this produces a wider variation of pressure for otherwise equal variations in the rate of fluid flow.

Background and summary of lhe invention This invention relates to control apparatus and more especially to what is, in effect, a fluid tranducer and a combination of electric switch means with provision for actuating the switch in response to a change in the flow of a stream of air or other fluid to the fluid transducer.

It is an object of the invention to provide an improved control apparatus with a minimum of moving parts and with actuating mechanism located along an air stream and responsive to deflection of the air stream. This communication between the switch actuator and the air stream is such that the deflection causes a change in pressure on the upstream side of the deflection, and preferably an increase in pressure.

Another object is to provide an improved pressureoperated switch that has a wiping contact action and snap action, and in which the contacts are enclosed in a sealed chamber, or whereby the switch operates indefinitely without attention and without requiring cleaning or replacement of contacts.

The invention provides a switch and an actuating system that is suitable for operation in response to the passage of a cam lobe across the air stream, or that is responsive to air stream deflection by passage of a Work piece along a conveyor, or between transfer stations of an automatic machine, or along a delivery chute.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

Brief description of the drawing In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views: 7

FIGURE 1 is a side elevation of an electric switch and an actuating system for the switch made in accordance with this invention;

FIGURE 2 is an enlarged sectional view on the line 22 in FIGURE 1;

FIGURE 3 is a sectional view, taken on the line 33 of FIGURE 1; and

FIGURE 4 is a sectional view on the line 4-4 of FIGURE 1.

Description of the preferred embodiment The switch and the actuating mechanism are preferably enclosed in a single, one-piece housing 10 having a chamber 12 therein with a shoulder 14 at an inter-mediate location along the wall of the housing where the diameter of the chamber 12 increases toward its upper end.

The chamber 12 is preferably of cylindrical cross section and it has a bottom surface 18 which supports a lower clamping element 20. This clamping element 20 fits snugly within the chamber 12 below the shoulder 14 and it has an annular groove around its upper portion for receiving a circumferential bead 22 of a flexible diaphragm 24, which is shown in the drawing with circular ribs 26 on its bottom surface radially inward from the bead 22. The disk or membrane portion of the diaphragm 24, which extends inward from the bead 22, passes across a relatively narrow top edge 30 of the lower clamping element 20.

The diaphragm 24 is clamped against the lower clamping eleinent 20 by a clamping ring 34 which compresses the material of the diaphragm 24 until the ring 34 abuts against the shoulder 14 of the chamber 12. Thus the shoulder 14 limits downward movement of the clamping ring 34 "and controls the maximum compression of the circumferential edge portion of the diaphragm 24 and the head 22 which seals in a manner similar to an O-ring. The diaphragm 24 is preferably a molded rubber element, but it can be made of various synthetics and it must be flexible. The degree of flexibility and the strength of the diaphragm 24 depends upon the size of the switch, the pressure under which it operates, and especially the desired sensitivity.

The clamping ring 34 is held in place by an insulating element 38 which fits snugly in the upper part of the hous ing 10. This insulating element 38 is clamped against the ring 34 by a flange 40 on a base 42 of a receptacle 44."The flange 40 is locked in place by rolling over the top edge of the housing 10.

The top edge 46 of the housing 10 is shown in full lines in FIGURE 1 in a rolled-over condition; and is shown in its original condition by dotted lines.

A contact carrier 50 is located in the chamber 12 above the flexible diaphragm 24. This contact carrier consists of a circular base 52 that extends across most of the open interior of the clamping ring 34, and the contact carrier 50 has an upwardly extending portion 54 to which is secured a movable contact 58 having a convex or hemispherical upper surface, preferably made of tungsten carbide.

There are two fixed contacts comprising buttons 61 and 62, carried by the insulating element 38 at locations immediately above the movable contact 58. When the flexible diaphragm 24 is in its normal, undistorted position, there is a clearance between the contact 58 and the buttons 61 and 62. When the flexible diaphragm 34 is moved upward by pressure from below, the contact 58 moves upward and touches both of the buttons 61 and 62 and closes a circuit from the button 61 to the button 62. Within the insulating element 38 there is a conductor 64 leading from the button 61 to a terminal 66 in the receptacle 44; and there is a corresponding conductor 64 leading from the button 62 to a terminal 66' in the receptacle 44.

To increase the amount of wiping action and distribute wear, the contact carrier 50 preferably has some lateral shifting of its position. Thus the contact 58 may touch one of the buttons 61 or 62 before it touches the other, but the slope of the faces of these buttons 61 and 6 2 deflects the contact 58 into the contact with the other button as the contact 58 moves upwardly. The buttons 61 and 62 are preferably made of tungsten carbide and they can be formed with concave contact faces.

The flexible diaphragm 24 has its mid portion secured to a disk 70 which is made of steel or other material that is attracted by a magnet. In the preferred construction there is a stud 72 integral with the disk 70 and extending into a socket in the bottom of the flexible diaphragm 24. This stud 72 is preferably bonded to the rubber or other material of the flexible diaphragm by adhesive or chemical bonding or in any other suitable way which causes the disk 70 to move up and down as a unit with the center of the diaphragm 70 without stifiening the diaphram 24 for any substantial distance outward from its center region.

The lower clamping element 20 surrounds a space 74 in which is located a permanent magnet 76, preferably an alnico magnet. This magnet 76 is bonded to the clamping element 20 at the bottom of the space 74; and it has poles 78 and 79 of a height to contact with the disk 70 when the flexible diaphragm 24 is in its normal, undistorted position.

Air enters the space between the poles 78 and 79 and flows from this space into the space 74 under the diaphragm 24. The air is supplied through a passage '80 in the magnet 76. The passage 80 registers with an opening 82 through the bottom of the lower clamping element 20; and this opening 82 is in alignment with a passage 84 extending through the bottom of the housing 10.

The initial air pressure under the diaphragm 24 does not move the diaphragm because of the attraction between the disk 70 and the magnet 76. As the air pressure under the diaphragm increases, the force against the bottom area of the diaphragm becomes suflicient to overcome the magnetic attraction between the disk 70 and the magnet 76 and the diaphragm then moves upwardly. This movement is a snap action because the magnetic attraction between the disk 70 and magnet 76 decreases rapidly with increase in clearance and the net upward force, therefore, rises rapidly as soon as upward motion begins.

The passage 84 opens into a chamber 86 which is closed on one side by a partition 88 and on the other side -by a plug 90 which is screwed into a threaded opening in the housing 10. At the bottom of the chamber 86, a continuation of the passage 84 extends to and opens through the lower end of the housing 10.

There is an air tube 92 extending through the partitio 88 and into the chamber 86. This air tube, which can be used for fluids other than air, extends across the to of the continuation o fthe passage 84. The end of the tube 92 in the chamber 86 is closed by an end wall 94; and there is an orifice 95 in the bottom of the tube 92 in position to discharge a stream of air (or other fluid) downward into the passage 84. Air is supplied to the tube from a supply line connected with the housing by a fitting screwed into a threaded opening 96. This threaded openings 96 is, therefore, the inlet of flow-through passages including tube 92, orifice 95 and the part of the passage 84 below the orifice 95. The lower end of the passage 84 is the outlet of these flow-through passages.

In FIGURE 1 the tube 92 appears to close off the chamber 86 from the continuation of the passage 84, but it is evident from FIGURE 4 that because of the small radius of the tube 92 as compared with that of the chamber 86, there is clearance on both sides of the tube 92 through which air can pass from the chamber 86 into the passage 84. The downwardly directed air stream from the orifice 95 aspirates air from the chamber 86 and causes a reduction in pressure in the part of the passage 84 above the chamber 86 and in the spaces under the diaphragm 24. Thus the tube 92 in the surrounding chamber 86 and with the downwardly directed orifice 95 is an aspirator.

As long as the stream of air flows from the orifice 95, down through the passage 84 and out through the bottom of the housing 10, the aspirating action maintains a reduced pressure under the diaphragm 24. Whenever the flow of air from the bottom of the housing 10 is partially,

or totally, obstructed, the aspirating action is reduced or terminated and there is an increase in the pressure in the chamber 86 and in the spaces under the diaphragm 24. With suflicient increase in pressure the diaphragm 24 moves upward lifting the disk 70 from the magnet 76 and the contact 58 touches the buttons 61 and 62 to close the switch as previously explained.

FIGURE 1 shows a cam 116 secured to a shaft .118 with which the cam rotates as a unit. The cam 116 has a lobe 120 which passes close to the lower end of the passage 84 during a portion of each rotation of the cam 116.

When the lobe 120 is remote from the passage 84 the stream of air flows downward and discharges from the lower end of this passage 84. The air pressure in the passage 84 and under the diaphragm 24 remains uniform as long as the stream of air issuing from the lower end of the passage 84 is undisturbed. The cam 116, and for that matter the shaft 118, provides some obstruction to the air stream at a distance from the passage 84, but any remote and partial obstruction which is constant, does not produce any pressure change in the space under the flexible diaphragm 24 of the switch actuator.

When the cam 116 turns far enough to bring the lobe 120 into the air stream issuing from the passage 84, this deflection of the air stream raises the pressure in this passage and under the diaphragm 24. If the obstruction of the stream is sufliciently severe to increase the air pressure to that which will lift the diaphragm 24, it closes the switch as previously explained.

The obstruction which deflects or otherwise interferes with the flow of air from the outlet end of the passage 84 may be a workpiece; and the location of the end of the passage 84 can be changed and can be made adjustable by connecting an extension tube, such as a flexible tube, to the end of the housing 10 in communication with the passage 84. If desired, a push button can be substituted for a workpiece or cam to obtain a manually-op erated switch.

It will be understood that the switch of this invention can be made to opearte on any desired pressure change by correlating the flexible area of the diaphragm 24 with the strength of the magnet which produces the snap action. The actuating mechanism can be constructed to respond to small air stream deflections, and the operation is extremely rapid becasue the effect is produced by a pressure wave and does not require the flow of quantities of gas.

The preferred embodiment of the invention has been illustrated and described but changes and modifications can be made and some features can be used in different combinations without departing from the invention as de fined in the claims.

What is claimed is:

1. Control apparatus including electric switch means, a switch actuator including a pressure chamber having a movable wall, flow-through passages including inlet and outlet passages through which a fluid flows, an aspirator having a suction chamber and having a fluid passage which is in series with said flow-through passages, the aspirator drawing a partial vacuum when there is flow of fluid through said fluid passage, a pressure-exchanging passage through which the pressure chamber of the switch actuator communicates with the suction chamber of the aspirator to change the pressure in said pressure chamber in accordance with the rate of flow of fluid through said flow-through passages.

2. Control apparatus including electric switch means, a switch actuator including a pressure chamber having a diaphragm extending across one end of the pressure chamber, said diaphragm being clamped in position around its circumferential edge and extending across the end of the pressure chamber in substantially the plane of the clamped circumferential edge of said diaphragm, flow-through passages including inlet and outlet passages through which fluid flows, a pressure exchange passage through which the pressure chamber is in communication with the flow-through passages through which the fluid flows, a sealed contact chamber on the side of the diaphragm opposite said pressure chamber, said switch means including a relatively fixed contact in said contact chamber, and a movable contact mechanically connected to and movable as a unit with said diaphragm toward and from the fixed contact in response to pressure changes in the flow-through passages characterized by a deflector in the path of flow of fluid that flows through the passages, the pressure-exchange passage connecting with said passages on one side of the deflector for response to the diflerence in pressure in said passages with changes in the amount of deflection of the stream of fluid flowing through said passages.

3. The control apparatus described in claim 2 characterized by the deflector being movable into different positions to change the amount of deflection of the fluid flow by said deflector.

4. The control apparatus described in claim 2 characterized by a magnet and armature, one of which is connected with the movable part of the switch means and the other of which is secured at a relatively fixed location for obtaining snap action of the contacts as they move away from one another and as they move into contact with one another.

5. The control apparatus described in claim 2 characterized by the contact chamber and the pressure chamber being enclosed in a unitary housing, the diaphragm separating the chambers from one another, the contact chamber being completely enclosed and hermetically sealed by said diaphragm and housing.

'6. Control apparatus including electric switch means, a switch actuator including a pressure chamber having a movable wall, passages through which a fluid flows, and a pressure-exchanging passage through which the pressure chamber is in communication with the passages through which the fluid flows, the switch actuator having a contact chamber on the side of the movable wall opposite said pressure chamber, including a relatively fixed contact and a movable contact operably connected with and movable by said movable wall, the contact chamber and the pressure chamber being enclosed in a unitary housing, the movable wall constituting a diaphragm separating the chambers from one another, the contact chamber being completely enclosed and hermetically sealed by said diaphragm and housing, characterized by the unitary housing having a lower portion through which the pressure-exchange passage and the other passages extend, the pressure-exchange passage extending upward, a counterbore in the upper part of the housing at the upper end of the pressure-exchange passage, an annular clamping element in the lower part of the counterbore and extending substantially across the diametrical width thereof, a ring in the counterbore above the peripheral portion of the annular clamping element, the diaphragm being clamped between the annular clamping element and said ring, and having a circumferential bead that extends to the inside diametrical limits of the counterbore at the level of the diaphragm for sealing the chambers on opposite sides of the diaphragm from each other, a plug closing the upper part of the counterbore and clamped against the ring, andmeans at the top of the housing holding the plug in the counterbore and against the ring. 7. Control apparatus including electric switch means, a switch actuator including a pressure chamber having a movable wall, passages through which a fluid flows, a pressure-exchanging passage through which the pressure chamber is in communication with the passages through which the fluid flows, an orifice in said passages through which the fluid flows, an aspirator operated by the. flow of fluid through the orifice, the pressure exchange passage being connected with the aspirator on the downstream side thereof, and characterized by the passages including a first cross passage that communicates with the pressure chamber through the pressure-exchange passage, a second cross passage constituting a supply passage for the fluid flow passages, an outlet passage at the downstream end of the fluid flow passages and having some communication with the first cross passage, the second cross passage having a portion that extends into the first cross passage and that constitutes a length of tubing of an outside diameter substantially less than the diameter of the first cross passage and at a location projecting across the upper end of the outlet passage to partially obstruct said outlet passage but with clearance around the sides of the tubing providing for flow of fluid from the first cross passage into the outlet passage, the end of the tubing in the first cross passage being closed and said tubing having a side opening therein in substantial alignment with the outlet passage for projecting a stream of fluid into the outlet passage to aspirate fluid from the first cross passage through said clearance around the sides of the tubing.

References Cited UNITED STATES PATENTS 3,042,769 7/ 1962 Campbell.

2,628,296 2/ 1953 Dillman.

2,729,968 1/ 1956 Segerstad 73-37.6 3,206,572 9/ 1965 Buehler.

3,23 0,323 1/ 1966 Concannon 20081 3,250,873 5/ 1966 Kudlaty.

BERNARD A. GILHEANY, Primary Examiner. H. BROOME, Assistant Examiner.

US. Cl. X.R. 200-83

Images