# US 4,391,127 A · Proximity sensor

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- Number: US 4,391,127 A
- Document ID: US4391127A
- Status: Granted
- Kind: A
- Application number: 06/252,519
- Filed: 1981-03-20
- Granted: 1983-07-05
- Earliest claimed: 1981-03-20
- Assignees: E. I. Du Pont de Nemours and Company
- Inventors: William E. Hawkins
- Web page: https://patentgrep.com/patent/US4391127A

## CPC

- H01H 35/00: Switches operated by change of a physical condition (operated by change of magnetic or electric field H01H36/00; thermally-actuated switches H01H37/00)
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)

## Abstract

A sensor for detecting a break in a continuously advancing web. A vacuum tube extends through a plenum in a jet body. Air under pressure is introduced into the plenum and discharges through an annular orifice surrounding the tube onto a flared end. A low pressure switch in communication with the tube senses the absence of a web from its normal path of advance adjacent the flared end.

## Claims

### Claim 1

A proximity sensor comprising:
a body having a plenum therein in communication with inlet and outlet passages;
an elongated tube extending through the plenum and projecting from the outlet passage, said tube having a lesser diameter than the outlet passage, presenting an annular discharge orifice, and a flared end located externally of said body and the discharge orifice; and
a pressure switch having a sensing chamber in communication with the tube.

### Claim 2 (depends on 1)

The sensor of claim 1 wherein said outlet passages terminates in a short, flared length and the flared end of said tube has a curved exterior.

### Claim 3 (depends on 2)

The sensor of claim 2 wherein is provided a shroud on said body, said shroud extending to a point beyond and being spaced from the flared end of said tube.