US2540941A - Latch mechanism - Google Patents

Description

Feb' 6, 1951 c. B. GRAHAM ETAL 2,540,941

LATCH MECHANISM Filed March 17, 1945 /M d M Patented Feb. 6, 1951 LATCH MECHANISM Clifton B. Graham and Vinton D. Carver, Oak Ridge, Tenn.. assignors, by mesne assignments, to the United States of America as represented by the United States Atomic sion Energy Commis- Application March 17, 1945, Serial No. 583,278

5 Claims. l

This invention relates to improvements in automatic latches or trigger mechanisms and is particularly concerned with a latch or trigger mechanism which is automatically operated and which can be made very sensitive to conditions to which it is responsive.

The primary object of the invention is to provide an automatic latch or trigger mechanism which is sensitive but which is very simple in design and construction and which has no unwieldy or cumbersome parts which are apt to bind or become inoperative as a result of wear or maltreatment.

An object of the invention is to provide an automatic latch or trigger mechanism comprising a spring latch member controlled by a detent, the detent being supported by a resilient tie member, and the tie member being arranged to oppose or restrain the latch spring while being readily movable at the point where it carries the detent so as to promote ease of actuation of the detent by automatic mechanism.

Another object of the invention is to provide an automatic latch or trigger mechanism comprising a. spring latch member and restraining means therefore comprising a detent carried on the end of a resilient tie member arranged to restrain the mechanism in latched position.

Another object of the invention is to provide a latch or trigger mechanism comprising a latch member having a notch therein engageable by a. detent carried on the end of a resilient bracket or tie member.

Various other objects of my invention and numerous of its advantages will become apparent Lfrom the following detailed description and annexed drawing wherein Figure l is a cross sectional view of a fluid dispensing nozzle having the device of my invention incorporated therein.

Fig. 2 is a sectional view taken along line 2-2 of Fig. 1.

Fig. 3 is a view taken along line 3--3 of Fig. 1.

The fo lowing detailed description describes an automatic liquid dispensing nozzle of the type which has an automatic shut-o5 mechanism for shutting 01T the flow through the nozzle when the container into which the liquid is being dispensed fills up, and the improved latch mechanism oi our invention is described in association with the automatic shut-olf mechanism of the nozzle. The device of our invention nds particular application in connection with a dispensing nozzle, as described, although it is understood that it may be utilized in many other ways and in many other devices. The dispensing nozzle is described `2 in connection with the dispensing of liquid nitrogen into liquid nitrogen traps as an example of one use of the nozzle.

Referring to Fig. l, numeral I designates the liquid nitrogen dispensing valve, the vvalve having a stem 2 extending upwardly into the housing 3 within which is the manual and automatic mechanism for operating the dispensing valve. The valve I is of conventional construction, the inlet being at the right and the outlet at the left and the port being designated 35. The valve member 36 seats upwardly and is urged in seating direction by a coil spring 31 which surrounds a guide stem 38 which extends downwardly from the valve member into a guide bearing 39 in the lower part of the valve casing. As shown, the housing 3 is separate from the valve body, being connected thereto by a tube 4 with the valve stem sealed by a corrugated expansible bellows 5. The stem 2 may be depressed to open the valve I by means of a handle 6 which has a lug I which forms a fulcrum at the top of frame 3 and to which is linked a latch member 8 which has a notch 9 in its center portion adapted to engage a roller on a rod I0 or pin forming a detent. Surrounding the member 8 is a coil spring II which bears against a disc I2 held in place by a. cotter pin I3.

The operation of the parts as so far described is that when -it is desired to open the valve I, handle 6 is merely depressed and this causes the handle to turn about its pivot, that is, iulcrum l, the stem 2 being thus depressed to move valve I in opening direction against biasing spring 3l which normally urges it in closing direction. When handle B is released spring 31 seals valve member 36.

The outlet of the valve I is connected to a Venturi tube I5having a restricted throat, the venturi being connected to the dispensing nozzle I6 and the nozzle carrying a shield I4 for protection against splashing.

The mechanism for automatically closing the valve I when the trap is filled with liquid nitrogen includes a corrugat d expansible bellows I l within the housing 3, th movable end of the bellows I'I carrying a yoke member I8 which engages the pin or rod Iii so as to be operatable to pull it out of the notch 9 when the bellows collapse. The pin or rod I0 extends transversely through the arms of yoke I8 and the roller on pin I0 is between the yoke arms so as to reduce friction in movement into and out of notch 9. (See Figs. 2 and 3.)

'I'he ends of rod I0 are engaged on the ends of spring brackets I9 extending upwardly from the bottom of housing 3, the ends of the brackets being narrowed, as may be seen on Fig. 3, and they are curled over, that is, around the ends of rod III outside of the yoke I8. Pin I9 has a head at one end and a cotter pin at the other end to hold it in place. Adjacent each bracket I9 is a slightly shorter leaf spring and the spring brackets and leaf springs are supported from a right angle bracket 49 attached to the bottom of casing .3 by screws II, the spring brackets and leaf springs being attached to bracket 49 by screws I2; Numeral 2| designates adjusting screws extending transversely through bracket 40 with their ends bearing against spring brackets I9. The position of screws 2| may be set by lock nuts as shown at 44. The purpose of adjusting screws 2|v is to adjust thevforce required to move the upper ends ofsprlng brackets I9 and pin III to the left, that is out of notch 9. When screws 2| are screwed against members I9 and 20 the force tends to bend or spring these members to the right (Figs. 1 and 2). Thus a greater force is required to move the upper ends of members I9 to the left. Screws 2| are suitably adjusted and in this way the iorce required to pull pin III out of notch 9 is adjusted. Spring brackets I9 'form resilient tie members which; through the detent formedV by pin I0, restrain upward movement of member 8 when pin III is engaged' in notch 9 in member 8.

The interior of the bellows I1 is connected by tube 23 to a plug member 24 having an internal recess which communicates through an oriiice member 25 and a channel 28 with the restricted throat of the venturi. The recess within plug member24 also communicates by means of a tube 21 with a vertical tube 28 extending downwardly within the vertical portion of the nozzle I6. At the upper end of tube 29 is a valve member 29 carried on the end of a rod 30 mounted longitudinally 'within the tube 28. The tube 28 and the rod are made of materials having different coeflicients of expansion so that the valve 29 is normally away from its seat to vent the tubes, but when the expanding nitrogen cornes in contact with the tube 28 and rod 30, contraction of the different metals cause valve member 29 to seat, thus closing the vent. The purpose of the structure just" described will become apparent below. l

In operation, when it is desired to ll a liquid 9 unlatching the latch mechanism, and when this happens, the valve I automatically closes. 'I'hat is, the spring which is part of valve I moves the stem 2 upwardly, moving fulcrum 1 bodily upwardly and pulling member 8 upwardly against the force of spring II. If the handle 6 is now released by the operator, the spring II will return the latch mechanism, and the fulcrum 1 back into the positions shown on Fig. 1 with the rod III reiatching into the notch 9 as soon as bellows I1 expands.

The purpose of the valve member 29 and the vent in the tube 28 is to prevent the automatic mechanism operating to close the valve in response to the initial now of vaporized liquid nitrogen which passes through the valve I when it is first opened. If the tube connections were not vented by valve member 29 when valve I is rst opened, this initial ilow of vaporized liquid nitrogen might. produce such a vacuum in venturi I5 as to operate the bellows mechanism causing nitrogen trap with liquid nitrogen, the nozzle I6 is inserted into the trap and then the valve Iis opened by depressing handle 6 in the manner described above. As the level of liquid nitrogen in the liquid trap rises, it immerses the lower end of the nozzle I 6 covering a small orifice 3| which communicates with the interior of tube 28. When this happens, the valve will automatically close in a manner to be described. When liquid nitrogen is flowing through the valve I and through venturi I5 a reduced pressure is produced in its restricted throat which tends to reduce the pressure in plug member 24 and also within the bellows -I1 which communicates by way of tube 23. l

When orice '3| is above the level of liquid nitrogen, however, there is very little evacuation, that is, reduction of pressure, and bellows 'I1 does not function. However, when orice 3| becomes covered, the pressure within the bellows I1 is reduced in the manner described and it tends to collapse, moving yoke member I8 and rod I0' to the left so that the rod is pulled out of notch it to close the valve. By the time that the initial ow of vaporized liquid nitrogen has passed, valve member 29 will have seated sealing the vent and thus preparing the system to automatically operate when the trap becomes illled with liqui nitrogen.

From the foregoing those skilled in the art will observe that we have provided an eilcient and sensitive latch mechanism characterized by simplicity of design and fabrication and possessing improved operating qualities.

`The foregoing disclosure is representative of the preferred form of our invention and it is intended that it be interpreted in an illustrative rather than a limiting sense, and that the scope of the invention be determined only in accordance withthe claims appendedhereto.

We claim:

l. An automatic latch mechanism, comprising in combination, a. latch member having latched and unlatched positions and having a portion adapted to be engaged by a detent, means urging said member toward unlatched position, re-

.` straining means comprising an element adapted to engage said portion and a bendable tensile member iixed at one end and attached at its free end to said element, said tensile member having a bending moment tending to hold said element in engagement with said portion, whereby said tensile member develops a tensile stress opposing said urging means and restraining said latch member in its latched position, and means operable to move said element against said bending moment out of engagement with said portion to release said urging means.

2. An automatic latch mechanism comprising in combination, a latch member having latched and unlatched positions and having a notch therein, means urging said member toward unlatched position, restraining means comprising a roller detent engageable in said notch, a bendable tensile member xed at one end and attached at its free end to said detent. and means bearing against said tensile member intermediate its ends to apply a bending moment to said tensile member tending to hold said detent in engagement with said notch, whereby said tensile member develops a tensile stress opposing said urging means and restraining said latch member in its latohed position, and means operable to move said detent and unlatched positions and having a portion adapted to be engaged by a detent, means urging said member toward unlatched position, restraining means comprising an element adapted to engage said portion and a bendable tensile member xed at one end and attached at'its free end to said element, said tensile member having a bending moment tending to hold said element in engagement with said portion, whereby said tensile member develops a tensile stress opposing said urging means and restraining said latch member in its latched position, means operable to move said element against said bending moment out of engagement with said portion to release said urging means, and means for adjusting the bending moment of said tensile member.

4. Apparatus, as claimed in claim 1, wherein said tensile member is positioned to extend generally parallel to the direction along which said latch member is urged by said urging means.

5. An automatic latch mechanism, comprising in combination, a latch member having latched and unlatched positions and having a portion adapted to be engaged by a detent, means urging said member toward unlatched position, restraining means comprising an element adapted to engage said portion, a bendable tensile member fixed at one end and attached at its free end at spaced positions to said element, and manually adjustable means bearing against said tensile member intermediate its ends to apply a bending moment to said tensile member tending to hold said element in engagement with said portion, whereby said tensile member develops a tensile stress opposing said urging means and restraining said latch member in its latohed position, and means operable to move said element against said bending moment out Vof engagement with said portion to release said urging means. CLIFTON B. GRAHAM. VINTON D. CARVER.

REFERENGES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS

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