US2211477A - Pneumatic detector switch - Google Patents

Description

Aug 13, l940. o. K. NoRMANN PNEUMATIC DETECTOR SWITCH Filed Nov. '7, 1959 gwoon/bw Olm/KMrmann www Patented ug. 13, 1940 PATENT OFFICE PNEUMATIC DETECTOR SWTCH Olav K. Normanni, Arlington, `ifa.; dedicated to the free use of the People in the territory of the United States Application November 7, 1939, Seriai No. 303,287

6 Claims.

(Cl. 20G-83) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described and claimed, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to me of any royalty there- I hereby dedicate the invention herein described to the free use of the People in the terri- Atory of the United States to take effect on the granting of a patent to me.

This invention relates to pneumatic detector switches and is more particularly concerned with a switch which may be used in conjunction with a pneumatic impulse traffic tube stretched across a highway for excitation by the wheels of Vehicles moving thereover and in conjunction with a counting mechanism which records the number of contacts made by the switch.

One of the objects of this invention is to provide a switch of the type mentioned which in operation does not depend upon the elasticity of any particular material, such as is required in the types of switches using flat diaphragms.

Another object of this invention is the provision of means for adjusting the operating characteristics of the device, especially its sensitivity.

Another object of this invention is the provision of an instrument of the type mentioned which is hermetically sealed, which may be easily dissembled and repaired, and which occupies a very small space.

The following description, considered together with the accompanying drawing, will disclose this invention more fully, its construction, arrangements, and combinations of parts, and further objects and advantages thereof will be apparent.

The accompanying drawing illustrates a longitudinal partial section of a device embodying the features of this invention in one of its preferred forms.

Referring with more particularity to the drawing in which like numerals designate like parts,

the numeral I designates the main housing of the instrument fabricated of an electrical conducting material, at one end of which is secured a nipple 2 by means of a reducer 3. The nipple 2 extends outward and is adapted to receive a trame impulse tube 4, which is made of a resilient material, such as rubber. This tube is an element well known in the art and is employed by stretching it across the highway where moving trafc runs over it and sends an air impulse through it. If desired, this tube may be open at its free end, or otherwise perforated, in accordance with recently developed practice in this art, to prevent surging. The other end of the nipple 2 extends within the reducer 3, over which is attached an inflatable sac 5 of rubber or any other 5 suitable material such as that commonly used as ink reservoirs in fountain pens.

On one side of the sac 5 there is disposed a strip of resiliently yieldable material 5, such as spring steel, the forward end of which is fixed 10 to the housing I by any suitable means, such as a lug 'l and a screw 8. The other end of the strip t is free and abuts a set screw 9 disposed through the wall of the housing, substantially as shown. By these means, the displacement 15 of the strip B with respect to the housing I may be adjusted. A pair of lips It are disposed, one on each side of the strip 5, to hold the sac 5 in place laterally. On the opposite side of the sac 5, there is disposed another resiliently yieldable 20 strip of material i I, preferably of spring steel. This strip of material l I is provided with a U-turn at the forward end forming a short arm I2 adjacent to the housing, the lon-g arm I3 being adjacent to the sac 5, and it comprises one of the 25 contact arms of the switch. The strip is secured to the wall of the housing by means of this short arm I2 and a screw Ill engaging pressure plate I5. Also this strip II is insulated from the housing I by any suitable means, such 30 as insulating blocks I6, inserted between it and the housing and insulating material Il and I8 introduced between the screw I4 and the housing. The long arm I3 of the strip II has a crimped portion I9 which presses against the sac 5, sub- 35` stantially as shown.

Opposite the long arm i3 of the strip II is disposed another strip or arm 25, also preferably of spring steel, comprising the other contact arm of the switch, and it is fixed at one end to the 40 housing I, the other end being free and terminating at substantially the same point along the axis of the instrument as the arm I3. At the free ends of the arms i3 and 20 are secured electrical contact points 2i and 22. The distance 45 between these two contact points is made adjustable by means of an adjustable abutment screw 23 disposed through the housing I and contacting the strip 20, substantially as illustrated.

The rearward end of the housing I is provided 50 with a cap 24, in threaded engagement, thereby completely enclosing the interior of the switch. The cap 24 is provided with an eye 25 which may be useful in securing the device in selected positions while in operation, such as to a post, tree, 55

and so forth. A binding post 26 is secured to cap 2&3 as a terminal for one of the electrical leads 2l, 27 of the recording mechanism circuit (not shown). The other terminal is provided by the screw I4 which is iitted with a floating nut 29.

The operation of this invention is as follows: The air impulse generated by a vehicle passing over the tube stretched across a highway causes the sac 5 to expand at points Where it is compressed by the arm l2, particularly at the point where thecrimp I9 contacts the sac. 'Ihis causes the arm i3 to move toward the arm 20, thereby causing the contact points 2l and 22 to touch, which closes the electrical circuit between the wires 2l, 2l attached to the terminals 26 and lli. When the impulse recedes, the contact between the points 2l and 22 is broken due to the release of pressure in the sac 5 and the resilient action of the strip H.

By means of the adjusting abutment screw 9, the sensitivity of the instrument may be regulated since this adjustment permits controlling the location of the sac 5 with respect to the arm i3. Also the distance between the contact points 2l and 22 may be adjusted by means of the set screw 23.

Having thus. described my invention, I claim:

i. A pneumatic detector switch comprising a housing, an inflatable sac within said housing communicable with a pneumatic impulse tube, electrical contact elements in juxtaposition to said sac and responsive to inflations thereof, means for adjusting the responsive relation between said sac and said contact elements, and means for adjusting the relation between said contact elements independently of said responsive relation.

2. A pneumatic detector switch comprising a housing, an inatable sac within said housing communicable with a pneumatic traflc impulse tube, a pair of resiliently yieldable arms secured within said housing, said arms being electrically insulated from each other, one of said arms being biased against said sac and the other being adjustably fixed to said housing, a pair of electrical contact points secured to said arms, one contact point for each arm, and means for adjusting the biased relation between said sac and its corresponding yieldable arm.

3. A pneumatic detector switch comprising a housing; an iniiatable sac within said housing communicable with a pneumatic traic impulse tube; a pair of resiliently yieldable arms secured Within said housing, said arms being electrically insulated from each other, one of said arms being biased against said sac and having a portion thereof projecting against said sac, the other arm being adjustably fixed to said housing; a pair of electrical contact points secured to said arms, one contact point for each arm; and means for adjusting the biased relation between said sac and its corresponding yieldable arm.

4. An article of manufacture comprising a tubular housing having a removable cap at its rearward end and a nipple conduit removably secured at its forward end, a resilientlyyieldable arm within said housing having one end secured at the forward end thereof, an adjustable abutment for the other end of said arm, an inflatable longitudinal sac resting on said yieldable arm communicating with said conduit, an electrical contact arm biased against said sac, another electrical contact arm opposite said first-mentioned contact arm and electrically insulated therefrom, means for adjusting the relation between said contact arms, and means for connecting said arms in an electrical circuit.

5. An article of manufacture comprising a tubular housing having a removable cap at its rearward end and a nipple conduit removably secured at its forward end, a resiliently yieldable arm within said housing having one end secured at the forward end thereof, an adjustable abutment for the other end of said arm, an iniiatable longitudinal sac resting on said yieldable arm communicating with said conduit, lateral abutments on said arm to hold said sac in alignment, an electrical contact arm biased against said sac, another electrical contact arm opposite said first-mentioned contact arm and electrically insulated therefrom, means for adjusting the relation between said contact arms, and means for connecting said arms in an electrical circuit.

6. An article of manufacture comprising a tubular housing having a removable cap at its f rearward end and a nipple conduit removably secured at its forward end, a resiliently yieldable arm within said housing having one end secured at the forward end thereof, an adjustable abutment for the other end of said arm, an inflatable longitudinal sac resting on said yieldable arm communicating with said conduit, lateral abutments on said arm to hold said sac in alignment, a crimped electrical contact arm biased against said sac, another electrical contact arm opposite said first-mentioned contact arm and electrically insulated therefrom, means for adjusting the relation between said contact arms, and means for connecting said arms in an electrical eircuit.

OLAV K. NORMANN.

Images