US3040842A - Pneumatic time delay device - Google Patents

Description

June 26, 1962 A. P. CHARBONNEAU 3,040,842

PNEUMATIC TIME DELAY DEVICE 2 Sheets-Sheet 1 Filed Aug. 30, 1960 June 26, 1962- A. P CHARBONNEAU l 3,040,842

` PNEUMATIC TIME DELAY DEVICE ite rates 3,640,842 PNEUMA'HC TIME DELAY DEVICE Aiian P. Charbonneau, Wauvratosa, Wis., assigner to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of' Delaware Y Filed Aug. 30, 196i), Ser. No. 52,879

9 Claims. (Cl. 188--95) This invention relates to an improved pneumatic time delay or retarding device.

While not limited thereto, this invention is particularly suitable for effecting time delay retarding actuation of electric switches.

Conventional pneumatic time delay devices are provided with llexible diaphragrns that move in cavities formed in rigid bodies with which'they form diaphragm chambers. Usually one such chamber is freely vvented to the atmosphere While admission of air into the other is at a controlled rate in accordance with the adjustment of a metering valve or pin in the passage to the latter chamber. As retarding action is normally desired only in one direction, some form of relief valve is provided between the ldiaphragm chambers, orbetween the chamber having air admission restriction and the atmosphere, to provide rapid exhaustion of the air from the last mentioned chamber. Relief valves heretofore used have added to the complexity of the devices and are a potential sourceof trouble during manufacture and operation of time delay devices.

It is a primary object of the present invention to provide novel and simple relief valving for flexible diaphragm type pneumatic time delay devices.

Another more spectifc object is to provide relief valving of the aforementioned character which is characterized by utilization of a portion of the diaphragm itself to seal exhaust porting in the rigid body during retarding operation, and to automatically unseal such exhaust porting during resetting operation of the device without need for any additional parts.

Other objects and vadvantages of the invention will hereinafter appear.

The accompanying drawings illustrate a preferred embodiment of the invention which will hereinafter be described, it being understood that the embodiment illustrated is susceptible of modications with respect to details without departing from the scope of the appended claims.

In the drawings:

FiGURE 1 is a top plan View of a base and valve body which forms part of the pneumatic time delay device incorporating the invention;

FIG. 2 is a side elevation view in cross-section of a pneumatic timing device in an initial operating position;

FIG. 3 is a view like FIG. 2 but showing the timing device in an intermediate position during its timing operation;

FlG. 4- is `a view like FIGS. '2 and 3 but showing the timing device in an intermediate position during its reset operation; and

FIG. 5 is a fragmentary sectional view taken along the line 5 5 of FIG. 1. l

As shown in FIGS. l and 2, the pneumatic timing device comprises the base and valve -body 10, a cover member 12, a flexible diaphragm 14, a connecting rod 16 having `an end stop 18 secured to the outer end thereof, a cup shaped member 20,7a coil compression spring 22. for

biasing cup member Ztl into engagement with an endstop 18. Covermernber 12 is provided with a pair of spaced apart parallel brackets 24 to which is pivotally mounted a lever 26 on a pivot pin 28 extending between and journaled in the brackets 24. Lever 26 is provided with 3,84%,842 Patented June 26, 1962 spaced apart parallel arms 26a which are interconnected by an L-shaped web portion 26h. The arms 26a terminate at substantially semi-circular end portions which underlie the upper flange 2da of cup member 20 on opposite sides of the latter. A portion '26C of the web 26b engages with the actuator button 30 of a switch 32 which is mounted on a member 34 secured between the brackets 24 by means of the screws 36. Switch 32 in one preferred -fo-rm is like that shown in the Koenig Patent No. 2,918,544, issued December 22, 1959, and may be lassumed to` have its actuator 30 biased to an outer extreme position when the switch is in one operating condition, and to be operable to another operating condition when its actuator is moved inwardly a given extent.

As best shown in FlG. l, the base and valve body member 19 is provided with a semi-spherical cavity 38 which at its center communicates through a short passage with the tapered inner end portion 42a of a passage 42 which extends to an open end at one side of body 10. An annular channel shaped exhaust recess 44 is concentrically formed in body 10 about the recess 38. Recess 44 communicates through short connecting passages 46 with the passage 48 that extends transversely across the bodyii) and intersects with the passage 42, at a right angle (see FIGS. 1 and 5). The passage 48 is enlarged at the outer ends thereof and filter screens 50 Aare mounted in such ends to entrap any foreign particles that might enter the body 10 through the passage 48. Body l0 is also provided with a substantially annular recess 52 of semi-circular transverse cross section which is concentric about the recess 44 and cavity 38.

Diaphragm 14 at its outer periphery is provided with a `bead i411 which is substantially circular in transverse `cross-section. The bead )t4-a seats in the recess 52. An annular flat portion 1415 connects the bead 14a with a central, molded semi-spherical portion 14C, which in its relaxed, unflexed condition depicted in FIG. 2 is complemental in form to, and seats throughout its extent with the surface of cavity 38. At the center of the portion 14e of diaphragm 14 there -is provided an upstanding portion 14d in which is positioned the enlarged circular end portion 16a of connecting rod 16. When forming diaphragm 14 by molding, end portion 16a and lower end of stem portion 16h yare molded securely in assembled 'relationship to each other.

Cover plate 12 is provided with portions 12a which are secured to body 10 by means of a plurality of screws 56, penetrate clearance openings therein and take into alined threaded recesses 58 in body 10i. Such portions bear `against and seal the head 14a of diaphragm 14 in place in recess 52. The portion 12a connects at an upwardly off-set angle with a central portion 12b that overlies the central portion 14C of diaphragm 14. Portion 12b is provided with a plurality of vent openings 6l) extending therethrough to provide free movement of air into and out of the upper diaphragm chamber. At the center of cover plate 12 there is formed a truste-conical boss `12e having an opening extending therethrough in which isl tted a nylon bearing bushing `62, that provides sliding bearing support for the stem 16h of rod 16. It will be seen that in the operating position of the device shown in FIG. 2 that there is a small clearance space X between .the upper surface of portion 14h of diaphragm 14 and the adjacent surface of portion 12a of cover 12 for a purpose that will be hereinafter explained.

Adjacent its outer end, passage 42 is suitably threaded to receive the threaded portion of a metering pin 64 which extends interiorly` of passage 42 and terminates at a tapered'end portion 64a concentric within the tapered portion 42a of passage 42. The tapers of the passage portion 42a and end portion 64a of pin 64 4are of relatively small included angles, and the taper of the passage portion 42a is slightly greater than the taper of end portion 64a of pin 64. As will be understood it pin 64 is screwed farther into the passage 42 greater restriction to the passage of air into cavity 38 will Yoccur whereas if the pin 64 is screwed outwardly, the restriction will be lessened.

FIG. 2 depicts the operating position of the device which is obtained following application of a force F of sufficient magnitude in the direction of the arrow. this position biasing spring 22 is compressed and lever 26 is moved to a counterclockwise extreme position wherein it has moved actuator 30 to an inward positio-n effecting operation of switch 32 to one` over-center operating condition. Let it be assumed that the force F is removed. The compressed spring 22 will then move member 20; and hence rod 16, upwardly. Due to its connection with rod 16 the central portion 14e of diaphragm 14 will be pulled upwardly. However, as air can only enter into the lower diaphragm chamber at a restricted rate through opening and passageway portion 42a a partial vacuum is developed in the lower diaphragm chamber thereby retarding the movement of portion 14e of the diaphragm away from the surface of cavity 38. Consequently rod 16 and cup member 20 are correspondingly retarded in their upward movement at a controlled rate.

During such upward movement, the portion 14C of the. diaphragm just pulls away from the surface of cavi-ty 38 at its center and continues to peel away radially from the surface -o' cavity 38 by lexure and Without yany appreciable elastic stretching thereof. As the portion 14e peels away from the surface of cavity, the intermediate portion 14h is held tightly in place over the open end of exhaust recess 44 due to the difference in pressure on the opposite sides of diaphragm 14. Thus air is prevented from entering into the lower diaphragm chamber through exhaust recess 44.

An intermediate position of the device during retarded upward movement of diaphragm portion 14C, rod 16 and cup member 20 is depicted in FIG. 3. As cup member 2t) moves up at a retarded rate lever 26 is relieved to pivot clockwise under the the bias of switch 32 exerted through its actuator 30 which moves outwardly of switch 32 in correspondence with the clockwise pivotal movement of lever 26. At a point beyond that depicted `in FIG. 3, actuator 30 will move to a position permitting switch 32 to move to its opposite over-center operating condition. Spring 22 will continue to move portion 14C, rod 16 and cup member 20 upwardly somewhat beyond the point where the last mentioned operation of switch 32 is elected until it rea-ches its uncompressed position. In its nal position, not all of the portion 14C of the diaphragm will be peeled away from the surface of cavity 38; the part thereof adjacent the portion 1417 still being in contact with the latter.

Y Assuming that the device has completed its upward retarding operation and has come to rest, let it be assumed that the force F is thereafter reapplied downwardly on stop 18 as depicted in FIG. 4. This results in downward movement of rod 16 and the portion 14e` of the diaphragm. 14C compresses the volume of air in the lower diaphragm chamber which then causes the diaphragm to Hex to a configuration substantially like that depicted in FIG. 4. It will be seen that any remaining part of the portion 14C peels away from the surface of cavity 38 and the inte-rmediate portion 14h is lifted olf into the aforementioned space X to uncover the open end of the recess 44 to provide for rapid exhaustion of air therethrough from the lowerV diaphragm chamber. Thus, once the recess 44 is in open communication with the lower diaphragm chamber the volume of air entrapped in the latter during the upward retarded movement of the diaphragm will be rapidly exhausted tothe atmosphere. Accordingly diaphragm 14, rod 16, cup member 24J and lever 26 will Inr The initial downward movement of portion picted in FIG.2, wherein the actuator 30 of switch 32 is moved inwardly to effect over center snap action operation of the latter to its first operating condition,

It will be seen from the foregoing that the form` of diaphragm 14 and its arrangement with respect to exhaust recess 44 provides simple and effective relief valving for pneumatic time delay or retarding devices. Such relief valving is not prone to sticking and obstruction from dust particles which has proved ltroublesome with respect to relief valves heretofore used. While in the embodiment disclosed the form of .the cavity in the body 10 and overlying molded diaphragm portion 14C Iare of complemental semi-spherical configurations, other curved congurations, such as trusto-conical may also be used.

I claim: l. In a pneumatic time delay device, a base having a -central cavity formed thereon, a flexible diaphragm sealed and secured at its peripheral margin to said base.

and having a central portion overlying and forming a chamber with said cavity, a movable member attached to said central portion of said diaphragm, a passageway formed in said base opening at one end into said cavity and openingat another end to the atmosphere, an adjustable meter-ing pin extending into a portion of said passageway and providing restriction .to the passage ofair into said chamber, a recess formed in said base and having its open side underlying `a portion of said diaphragm intermediate its peripheral margin and central portion and having connection to the atmosphere through said base, said diaphragm upon movement of said member away from said base liexing its central portion to cause air to be drawn into said chamber thro-ugh the restriction in said passageway while atmospheric pressure on the other side of said diaphragm maintains said intermediate portion in sealing engagement with the open side of said recess to prevent unrestricted entrance of air into said chamber through the latter, and said diaphragm upon following movement of said member toward said base flexing 'to-cause its intermediate portion to lift off the open side of said recess to permit rapid exhaustion through said recess of air from said chamber to the atmosphere.

2. The combination according to claim l, wherein said recess is annular and surrounds said cavity in said base..

3. The combination according to claim 1, wherein the central portion of said diaphragm is molded to have a shape complemental to the surface of said cavity and to seat throughout its extent with such surface when substantially all air is displaced from said chamber.

4. The combination according to claim 3, wherein the peripheral margin of said diaphragm is circular in transverse cross section and said intermediate portion thereof is iiat in relaxed state,

5. In a pneumatic retarding device, a ilexible diaphragm, rigid base and cover members, said diaf phragm having a peripheral margin secured in place between said members and a central portion defining on one side a first diaphragm chamber with said base member and defining on its opposite side a second diaphragm chamber with said cover member, said cover member having openings therein freely venting `said second diaphragm cham-ber to the atmosphere, a rod extending through and having sliding bearing support in said cover member and having connection with said central portion of said diaphragm, a passageway formed in said base member opening at one end into said first diaphragm chamber and at the other end through a wall of said base to the atmosphere, la metering pin in said base member Y affordin g restriction to passage of air through said passageway into said first diaphragm chamber, ya recess formed in said base member and having its open side underlying a portion of said diaphragm intermediate its peripheral margin and having unrestricted connection through said base member to the atmosphere, said diaphragm upon movement of said rod outwardly of said cover member flexing its central portion toc'ause air to ow into said first diaphragm chamber at a restricted rate through said passageway and along its intermediate portion sealing .the open side of said recess toprevent unrestricted entrance of air into said tir-st diaphragm chamber, `and said diaphragm upon following movement of said rod inwardly of said cover member exing to cau-se lifting of its intermediate portion ot the open side of said recess to provide rapid exhaustion of'air from said first diaphragm chamber.

6. The combination according to claim 5, wherein said member is provided with a cavity underlying said central portion of said diaphragm and said recess is of channel form in transverse cross section and surrounds said cavity. f

7. The combination according to claim 6, wherein said central portion of said diaphragm is molded to have a stantially all air is displaced from said first diaphragm chamber.

8. The combination according to claim 7, wherein'said cavity is of semi-spherical form and said central portion v of said diaphragm is molded to have a complemental semi-spherical shape. t

9. The combination according to claim 8, wherein said peripheral margin of said diaphragm is circular in transverse cross section and seats on a semi-circular transverse cross section recess formed in said base member and surrounding said cavity and the first mentioned recess and wherein said intermediate portion of said diaphragm is at in relaxed state.

References Cited in the le of this patent UNITED STATES PATENTS

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