US3362573A

US3362573A - Quick release explosion-proof enclosure

Info

Publication number: US3362573A
Authority: US
Inventors: Jr Nathaniel B Wales
Original assignee: METRODYNAMICS CORP
Current assignee: METRODYNAMICS CORP
Priority date: 1966-05-10
Filing date: 1966-05-10
Publication date: 1968-01-09
Anticipated expiration: 1985-01-09

Description

Jan. 9, 1968 N. B. WALES, JR 3,

QUICK RELEASE EXPLOSION-PROOF ENCLOSURE Filed May 10, 1966 2 Sheets-Sheet l w/w l z I j! 34 5 1; J4 44 40 44 5/ INVENTOR A20 JQ WMQ/ 6. MA g) Jan. 9, 1968 N. B. WALES, JR 3,362,573

QUICK RELEASE EXPLOSION-PROOF ENCLOSURE Filed May 10, 1966 2 Sheets-Sheet 2 INVENTOR United States Patent 3,362,573 QUICK RELEASE EXPLOSION-PROOF ENCLOSURE Nathaniel B. Wales, Jr., New York, N.Y., assignor to The Metrodynamics Corporation, Red Bank, N.J., a corporation of New Jersey Filed May 10, 1966, Ser. No. 549,032 4 Claims. (Cl. 220-55) This invention relates to explosion-proof enclosures for spark producing electrical equipment to be used in explosive atmospheres, and, in particular, to a quick release mechanism to facilitate the servicing of such enclosures.

The requirement for this class of enclosure is that when the atmosphere both within and surrounding the enclosure is explosive, the ignition of the explosive atmosphere within the enclosure will not ignite the surrounding explosive atmosphere.

One popular design approach to satisfy this requirement is to build the enclosure with enough strength to contain the explosion without injury thereto, and to provide enough metal flange area and smoothness at the parting plane of the enclosure, so that any escaping products of combination will be sufliciently cooled in their path of exit as to be incapable of igniting the outer explosive atomsphere.

In the conventional such enclosure it is the practice to provide a large number of closely spaced bolts around the periphery of the foregoing flange, threaded into the lower flange lip.

Evidently, this construction requires a large amount of maintenance labor each time the cover of the enclosure has to be removed for servicing or inspection.

The present invention obviates this expensive maintenance by teaching the use of an automatic interlinked system of syring actuated clamping dogs which provide a means for rapidly clamping or releasing the cover of such an explosion-proof enclosure, while maintaining the specified clamping force capability.

An important feature of this invention is the provision of a means to equalize the clamping forces of the several dogs in spite of the mechanical tolerance differences between the several clamping devices and their interconnecting linkages.

Another advantage of this mechanism is that a simple visual inspection of the position of its operating handle gives assurance that all of the clamping stations are in the proper state of predetermined clamping stress. This is in contradistinction to the bolt type construction, which requires individual use of a torque wrench on each bolt.

The principal object of the present invention is to provide a multiple clamping device of the closure lids of explosion containing enclosures which permits the rapid manual clamping or release thereof.

Another object of the invention is to provide a quick release device for explosion-containing enclosures which gives visual indication as to the integrity of clamping of the lid thereof.

Still another object of the invention is to provide a quick clamping-release mechanism design for the lids of explosion-containing enclosures which is reliable in operation and economical to manufacture.

A further obect of the invention is to provide a manual handle operated mechanism for clamping the lids of explosion-containing enclosures at several stations in such a way that the clamping forces at these stations are substantially equalized in spite of mechanical differences between the several clamping mechanisms.

For other obects, and a clearer understanding of the present invention, reference is made to the following detailed specifications, to be taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a plan view of the preferred embodiment of the invenion;

FIGURE 2 is side View in elevation taken through the plane 2-2 of FIG. 1;

FIGURE 3 is a plan enlarged view through 3-3 of FIG. 4 showing the clamping cam in its closed position;

FIGURE 4 is a sectional enlarged view through 4-4 of FIG. 1;

FIGURE 5 is a plan enlarged view through 3--3 of FIG. 4, showing the clamping cam in its open position;

FIGURE 6 is an elevational view through 6-6 of FIG. 3;

FIGURE 7 is a sectional view through the clamping cam of an alternative construction of the subject invention; and

FIGURE 8 is a plan view through 88 of FIG. 7 showing the absence of slots in the control link.

Referring to the device shown in FIGURES 1 through 6, it may be seen that the explosion-containing enclosure comprises a lower housing or casing 20, preferably made of a heavy cast metal such as cast iron or aluminum alloy, and an upper cover or lid 21 made of the same metal.

Casing members

20 and 21 have lip or

flange areas

24 and 23 respectively, which are machined to mate in a closure plane. Flange 24 is provided around its periphery with a plurality of approximately equally spaced enlarged land or shelf areas 25 each of which supports an Oilite bushing 29.

A combination clamping cam dog and lever member 26 is journalled in each bushing 29 and secured thereto by a washer 28 and E ring 29 which resiliently embraces a groove in the spindle portion of cam 26.

Each cam 26 has an inclined ramp cam surface 31 forming a ledge which can clamp down on the upper lid flange 23 when it is rotated clockwise to the position shown in FIGS. 1 and 3.

When cam 26 is rotated counter clockwise by approximately to the position shown in FIG. 5 it brings a portion 30 of the cam which has been cut away along a chord into parallelism with the edge of cover flange 23, thereby releasing the cover 21 for opening by rotation about the axis of a hinge formed by cover lugs 41, enclosure lugs 42 and hinge pins 43. The angle of inclination A of the cam ramp surface 31 may be seen in FIG. 6.

It is to be noted that although the device will operate using the inclined ramp surface 31 and a flat horizontal flange surface 23, lower pressures and a better operation will result if the casting 21 provides correspondingly inclined ramp surfaces on the flange 23 at each clamping station.

The cam levers 26 are all interconnected by a linkage system which starts with a handle lever 37, pivoted on a stud 45 secured to an enclosure boss 38. Lever 37 is pivotally secured to the first of a series of links 33 by a stud 24. Three additional links 33 are each sequentially linked together for parallelogram type motion by means of three bell cranks 40, six additional pivot studs 44 and three corner bosses 39 extending from encloure casting 20 to provide a seat for the bell crank pivot studs 45.

Each link 33, in this form of the invention, is provided with a slot 36 at each clamping station. Each cam lever 26 is provided with a grooved drive pin 32 forced into the outer top end of the lever portion of cam 26.

Slots 36 are positioned so that each embraces a cam lever drive pin 32, and each lever 33 is provided with a grooved spring anchor pin 35 located beyond the clockwise (FIG. I) end of each slot 36, so that an extension spring 34 hooked between

pins

32 and 35 will tend to keep drive pins 32 at the clockwise (FIG. 1) end of slots 36 with a predetermined force.

In operations of the device of FIG. 1, handle 37 is rotated 90 (FIG. 1) counter clockwise to release the enclosure. This will force each cam 26 to also rotate counter clockwise (FIG. 1) through the

linkage

33, 40 acting on drive pins 32 until each cam is in the same position as that shown in FIG. 5 relative to the edge of the cover 23. Since the cams 26 are no longer clamping or blocking the cover 21, it may be opened on its hinge pins 43.

To clamp the enclosure, the lid is closed, and lever 37 is rotated clockwise (FIG. 1) 90. This causes drive pins 32 to be urged clockwise by the resilient spring members 34. When the clamping torque on each cam 36 reaches the predetermined spring force, continued clockwise motion of handle 37 will cause the pin 32 for any given cam 26 to leave the end of its slot 36 and to extend the corresponding spring 34.

It is evident that without this equalizing spring coupling, that is, with the structure of FIG. 4 and with pins 32 rigidly journalled in links 33, the motion of handle 37 would stop at the first clamping of any cam 26, thus leaving all the other cams not fully clamped, because it is not possible to build any mechanism without dimensional tolerance.

Referring now to the alternative design of FIGURES 7 and 8, it may be seen that the design is identical to the design of FIGS. 1 and 4, except that slots 36, in links 33 are replaced by a simple hole which pivotally directly secures each lever portion of cam 26 by means of a shouldered stud 52. The other difference is that the spindle portion of cam 26 is lengthened by enough to accommodate a conical Belleville metal spring and a heavy washer 51 in between the same washer 28 and retaining E ring 27. The design of spring 50 and the dimensions of the parts in such that cam 26 is urged to seat on surface 25 and bushing 29 with a predetermined axial force.

The operation of the alternative design of FIGS. 7 and 8 is as follows. As before, counterclockwise motion of handle 37 will open all cams 26.

However, in clockwise closure and clamping of handle 37, as each clamping cam 26 develops the foregoing predetermined axial force, the Belleville spring 50 will begin to compress allowing the cam 26 to rise in its socket 29, thereby allowing the handle 37 to complete its stroke, even though each cam begins to overcome its conical spring 50 at a different instant during the stroke.

Again, equalization has been achieved between the cam clamping forces by inserting a resilient spring member in series relation between the common drive linkage 33, the cam lever 26, and the force reaction surface 25 for each cam.

In other words, either spring 5% or spring 54 forms a resilient means to place in serial force relation a link 33, a cam-lever 26, and the casing 20.

The scope of this invention is defined in the following claims.

What is claimed is:

1. A quick release explosion-containing enclosure comprising:

an enclosure casing having a peripheral flange;

an enclosure lid havin a peripheral lip;

a plurality of clamping cams secured to said casing and adapted to clamp together said flange and said lip at a corresponding plurality of clamping stations substantially equally spaced around the periphery of said casing;

a driving lever for each said clamping cam;

a link member for each side of said casing displaceably secured to said casing;

means to couple each of said link members into similar displacement;

manual handle means to displace said link members relative to said casing; and

resilient means for each said clamping cams to place in serial force relation one of said links, said lever, said cam, and said casing.

2. In a device according to claim 1:

said clamping cams comprising a combination spindle and lever journalled in said flange, each having an inclined ramp portion adapted to clamp said lip against said flange, and a portion cut away along a chord for releasing said lid member.

3. In a device according to claim 1:

said displacement comprising the translation of said links parallel to the flange of said enclosure;

said means to couple each said link member into similar displacement comprising bell cranks; and

said resilient means comprising helical extension springs coupling said links to said levers.

4. In a device according to claim 2:

said resilient means comprising a conical spring urging said spindle to seat in said journal in said flange.

References Cited UNITED STATES PATENTS 6/1950 Jacob 114-117 6/1950 Schiif 114l17

Claims

1. A QUICK RELEASE EXPLOSION-CONTAINING ENCLOSURE COMPRISING: AN ENCLOSURE CASING HAVING A PERIPHERAL FLANGE; AN ENCLOSURE LID HAVING A PERIPHERAL LIP; A PLURALITY OF CLAMPING CAMS SECURED TO SAID CASING AND ADAPTED TO CLAMP TOGETHER SAID FLANGE AND SAID LIP AT A CORRESPONDING PLURALITY OF CLAMPING STATIONS SUBSTANTIALLY EQUALLY SPACED AROUND THE PERIPHERY OF SAID CASING; A DRIVING LEVER FOR EACH SAID CLAMPING CAM; A LINK MEMBER FOR EACH SIDE OF SAID CASING DISPLACEABLY SECURED TO SAID CASING; MEANS TO COUPLE EACH OF SAID LINK MEMBERS INTO SIMILAR DISPLACEMENT; MANUAL HANDLE MEANS TO DISPLACE SAID LINK MEMBERS RELATIVE TO SAID CASING; AND RESILIENT MEANS FOR EACH SAID CLAMPING CAMS TO PLACE IN SERIAL FORCE RELATION ONE OF SAID LINKS, SAID LEVER, SAID CAM, AND SAID CASING.