Pneumatic-electric Switch Apparatus With Lock-out Feature

Abstract

An apparatus comprising a plurality of electric switches, pneumatic actuators for the switches, means for preventing inadvertent actuation of one or more switches and means for supporting the previous elements in coactive relation.

Description

FIELD OF THE INVENTION

This invention relates to the art of remotely actuable switching systems comprising low-force snap switches and pneumatic actuators, and including structure for preventing actuation of one or more switches. The invention finds particular application in explosive atmospheres where sparking in conventional switches could provide dangerous and in situations where the operator of the switch may be particularly sensitive to electric shocks, as in electrically adjustable hospital beds.

DESCRIPTION OF THE PRIOR ART

Numerous pneumatically actuated electric switch systems have been suggested in the past. U.S. Pat. No. 2,838,629 to Panzenhagen shows a remotely controlled switch in which pressure exerted on a collapsible hand bulb is transmitted through a tube to a bellows which expands to actuate a piston which closes the switch. No provision is made for the means for preventing actuation of the switch in the manner of this invention. U.S. Pat. No. 2,875,291 to Armstrong et al. shows a pneumatically operated switch in which air movement causes a ball or piston to move and close the switch circuit. A shield on the squeeze bulb prevents some types of inadvertent actuation of the device; however, the unique mounting structure and actuation preventor of this invention are not shown. U.S. Pat. No. 2,080,720 to Downs et al. shows a remote control switch operating device in which manually displaceable pistons force liquid through tubes to displace other pistons which, in turn, function to close the electrical switches. Although ganged switches and their actuators are shown, the simple structure of this invention and its actuation preventing means are not suggested.

U.S. Pat. No. 3,174,161 to Black shows a known hospital bed structure in which the structure of this invention would find particular utility. The bed is adjustable by the patient using a pendant placed nearby which includes rather conventional electrical switches connected to motors for raising and lowering the entire bed, the head or the foot of the bed. Although means are provided for electrically preventing actuation of the head and foot elevating positions, no disclosure is made of the simple mechanical apparatus of this invention. U.S. Pat. No. 3,187,136 to Corder et al. shows a multiple pressure switch construction in which individual switches respond to different magnitudes of pressure acting on a common diaphragm; however, no means for preventing inadvertent actuation in the manner of this invention is disclosed. Similarly, U.S. Pat. No. 3,631,389 to Elliott shows a hydraulically actuated switch assembly which fails to include the unique means for preventing actuation as in this invention.

SUMMARY OF THE INVENTION

An object of this invention is to provide a simple, easily manufactured combination of pneumatic actuator, electrical switch and non-electrical means for preventing actuation. To this end are provided a base plate, means for supporting a plurality of pneumatic actuators, a plurality of low-force snap switches having their actuating arms disposed in proximity to the pneumatic actuators and means located in the path of movement of the actuating arms for selectively preventing their movement when the pneumatic actuators are operated.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a perspective view of the invention, partially exploded;

FIG. 2 shows a plan view, partially in section, taken along line 2--2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

There follows a detailed description of the invention, reference being had to the drawing in which the numerals depict like elements of structure in the FIGURES.

FIG. 1 shows a perspective view of the invention. In practice, most elements of the invention except the switches, screws and other fasteners may be made of hard rubber or high impact plastic which facilitates their manufacture by well-known molding techniques and their assembly using common glues.

Base plate 10, of generally rectangular configuration, is provided along one edge with a plurality of stanchions 12 which may be used to support pneumatic actuators 14, such as shown in my copending application Ser. No. 242,515, or other such actuators. Each stanchion 12 comprises a rectangular support plate 16, attached to base plate 10 by suitable fasteners such as screws 18. Extending integral with and upwardly from support plate 16 are actuator supports, which comprise parallel wall portions 22 and 24 on opposite sides of support plate 16 and oppositely facing wall portions 26 and 28 respectively integral with wall portions 22 and 24 on one end of support plate 16, thereby defining stanchion slot 30. See FIG. 2. Pneumatic actuators 14 include a base section 32 having a portion 34 of reduced diameter somewhat smaller than the width of stanchion slot 30 and somewhat wider than the thickness of oppositely facing wall portions 26 and 28. In this manner, a plurality of pneumatic actuators 14 may be stacked in each stanchion 12 as shown. Tubes 36 extend from each pneumatic actuator 14 to a remote pneumatic selector switch unit 38.

Spaced toward the opposite edge of base plate 10 from the stanchions 12, are low-force snap switches 40 of a type well known in the art. The switching elements are located within housing 42 and are actuated by finger 44 extending therefrom into contact with elongated spring arm 46. Switches 40 are located such that end 48 of spring arm 46 lies in light contact with pneumatic actuator 14 prior to its actuation. When the operator at unit 38 actuates pneumatic actuator 14, the actuator deflects spring arm 46, FIG. 2, and actuates the associated switch 40. Switches such as the common 3TMT18-4 have been found to be suitable for the invention, and may be stacked, with appropriate spacers (not shown), on posts 50 and 52, which are attached to base plate 10.

Aligned approximately with the center of stanchion slot 30 and spaced therefrom is preventor assembly 54 for rendering selective switches 40 inoperable. Preventor base 56 includes counter bore 58 and detents 60 and 62, at right angles to each other. Rotatably mounted within counter bore 58 is reduced diameter section 64 of preventor lock shaft 66. Extending radially from lock shaft 66 is spring arm retainer 68. Preventor assemblies 54 and switches 40 are maintained in proper spatial relationship by retainer plate 70, which is attached to switches 40 at posts 52 and includes spaced ears 72 having bores 74 which receive the upper ends of preventor lock shafts 66. When the lower end of the spring arm retainer 68 rests in either detent 60 or 62, the ears 72, of resilient material, bear against the upper end of spring arm retainer to hold it in its selected position. In some applications, it may be desirable to form spring retainer 68 of plural, circumferentially and axially displaced portions, to permit some of the pneumatic actuators in a given stanchion to actuate their corresponding switches, while preventing others from doing so.

In use, the entire assembly is enclosed within a housing 76, shown in phantom, through the upper surface of which extend the preventor lock shafts 66. If the device of the invention is applied to a hospital bed such as shown in Black, previously discussed, one, two or three pairs of pneumatic actuators and switches could be used as desired, depending upon the existing adjustability features of a particular hospital bed. In FIG. 2, the effect of the spring arm retainer 68 is shown. In one case, the retainer 68 has been rotated into contact with spring arm 46 to retain it from moving under the action of its pneumatic actuator 14. In the other case, the retainer 68 has been rotated out of contact with its spring arm 46, thereby permitting its pneumatic actuator 14 to distend as shown and move spring arm 46 to actuate switch 40. Housing 76 and its contents would be placed out of reach of the patient where the appropriate spring arm retainers may be set to permit the patient to adjust the bed.

Claims

Having described my invention in such detail as to enable one skilled in

1. In a fluid pressure actuated electrical switching apparatus:

A. a switch having:

i. a mounting support; and

ii. an elongated resilient arm for actuation of said switch;

B. an expandible fluid pressure actuator operable to displace said arm to thereby actuate said switch;

C. said actuator including:

i. a cylindrical base section having a portion of reduced diameter intermediate the ends thereof;

D. a support for said actuator including:

i. a base support plate;

ii. horizontally spaced upstanding walls on said base support plate defining therebetween a vertical slot having a width less than the diameter of said cylindrical base section of said actuator and greater than that of said reduced diameter portion;

E. said reduced diameter portion of said actuator being engaged in said vertical slot and mounting and supporting said actuator in operable juxtaposition to said arm for actuation therethrough of said mounted switch upon operation of said actuator; and

F. stop means having selective active and inactive positions mounted adjacent said arm and operable upon movement to one or the other of said positions to selectively permit or prevent displacement of said arm by said actuator and thereby selectively control operation of said switch.

2. Apparatus as claimed in claim 1, said stop means including:

i. a rotatably mounted vertical shaft positioned proximate said arm;

ii. a longitudinal radial extension on said shaft;

iii. mounting means for said shaft permitting rotation thereof between a first position in which said radial extension engages said arm and prevents displacement thereof, and a second rotated non-engaging position with respect to said arm wherein said arm is free to move and actuate said

3. Apparatus as claimed in claim 2, said mounting means for said shaft including:

i. a base having a bore and angularly displaced detent slots therein;

ii. said shaft being rotatably and vertically displaceably mounted in said bore;

iii. a portion of said radial extension on said shaft being selectively engageable in one or the other of said detent slots upon vertical upward displacement of said shaft, rotation, and downward release thereof, said radial extension when in one said detent slot engaging said arm, and in the other said detent slot freeing said arm for switch actuating movement.

4. Apparatus as claimed in claim 3, including resilient means engaging said shaft having said radial extension and resiliently biasing said radial

5. Apparatus as claimed in claim 4, wherein a plurality of said switches and said actuators are vertically juxtaposedly mounted, and said resilient means resiliently engage the tops of the uppermost switch and said radial extension for maintaining spatial positionment of said switches and said stop means.