US2282011A - Pressure cooker and similar container - Google Patents

Description

'May 5, 1942. A. VISCHER, JR

PRESSURE COOKER A ND SIMILAR CONTAINER 2 Sheets-Sheet 1 4 Filed Nov. 18, 1938' QM QM mm ill/IA 3 WM @QQdMZ May 1942- A. vls cHER, JR

PRESSURE COOKER AND SIMILAR CONTAINER Patented May 5, 1942 PRESSURE COOKER AND SIMILAR CONTAINER Alfred Vischer, Jr., Park Ridge, 111., assignor to V 2 Vischer Products Company, Chicago, 111., a corporation of Illinois Application November 18, 1938, Serial No. 241,118

31 Claims.

The invention relates generally to-closures for containers, and more particularly to improvements in pressure cookers.

Most pressure cookers now on the market are provided with clamps and sealing means of various kinds to hold the cover in place. These clamps must be very strong since the total force which they must be capable of withstanding may be as high as several thousand pounds. The clamping means must therefore be of substantial construction, and the container or pot or the cooker must he of sumcient strength at the point where the clamps are attached to form a suitable anchorage ior the clamps. Furthermore, in pressure cookers provided with cover clamps it is necessary to make the cover very heavy and strong in orderto prevent its edge from raising from the kettle between the clamps.

It is an object of the invention to provide an improved form of closure for pressure cookers and similar containers in which the usual clamps to hold the cover in place are unnecessary.

A further object is to provide an improved circular closure for a container, which is larger in diameter than the diameter of the circular opening in the container, and which is normally warped or may be warped so as to be insertable into the container through the opening.

A further object is to provide an improved closure for pressure cookers and similar containers in which the closure cannot be removed until the pressure in the container drops to substantially atmospheric pressure, thereby to eliminate the dangers of escaping steam, due to premature opening of the container.

A further object is to provide an improved pressure cooker having a closure which will be held in place by the pressure within the container, and in which the effectiveness of the seal will increase with increased pressure within the container.

Other objects will appear irom'the following description, reference being had to the accompanying drawings, in which: v

Figure l is a perspective view of the pressure cooker;

' Figure 2 is a central vertical sectional view; Figures 3 and 4 are sectional views taken on the lines 3-3 and 44 of Figure 2;

I Figure 5 is an enlarged fragmentary sectional view showing the seal between the cover and the Figure 7 is a view showing the cover in its warped position, the section being taken in a plane perpendicular to that of Figure 6;

Figure 8 is a central vertical sectionalview of a modified form of the invention;

Figure 9 is a transverse sectional view taken on'the line 9-9 of Figure 8;

Figure 10 is an enlarged fragmentary sectional view showing the seal between the cover and the saucepan; and

Figure ii is a plan view diagrammatically illustrating the position of the cover in the saucepan prior to being drawn into sealing relation ship with the saucepan.

in the accompanying drawings, the invention is illustrated as applied to pressure cookers, it being understood that while the invention is of a particular utility in this form, it may be utilized in other'kinds of apparatus.

This application is a continuation in part of my copending application Serial No. 108,197, filed October 29, 1936, which application was a continuation in part of my application Serial No. 723,831, filed lviay 4,1934.

The form of the invention shown in Figures 1 to 7 includes a saucepan it shown as a casting, preferably made of aluminum or an aluminum alloy. The saucepan is generally cylindrical in shape, but at its upper end is of reduced diameter to provide a cover guiding surface it, a cylindrical cover centering wall it, and a hori zontal downwardly racing seating surface it.

- The surface it is preferably machined or otherwise suitably finished to make it substantially plane and smooth. The saucepan it is provided with an integral handle socket boss 22 in which a nut it is cast as an insert. A hardened, knurled metal ferrule it is pressed into a bore 3t formed in the socket boss 22, and has a handle it, preferably of a suitable heat insulating molded plastic material, fitted therein. The handle is preferably hollow and has its outer end closed by a cap 32 provided with a metal insert washer it. The handle is secured in the bore tli by a handle rod 36, the inner end of which is threaded in the nut 24 and the outer end of which is provided with an eye 38 for convenience in hanging the cooker upon a hook.

The closure or cover 40 for the saucepan it, when in operative position, as shown in Figure 2, has a shape corresponding substantially to that of the surface of a sphere, and is circular in its projection upon a horizontal plane. As best shown in Figure 5, the cover 40 has an upwardly directed peripheral flange 42 and is provided with gasket 44 which may be made of suitable heat and moisture resistant synthetic rubber substi-. tute which is bonded to the cover 40. The cover has a central hole 48 formed therein to receive a centrally drilled screw 48 which serves as a fas-' tening means for a connection fitting 50. The fitting 58 is internally threaded to receive the attaching screw 48, and is provided with an annular groove receiving a gasket 52 for sealing the joint. The attaching screw 48 has a pair of perpendicular diametral kerfs 54 which, in addition to'providing a slot for a driving tool, form ducts for the flow of steam into the fitting 50, and thus hinder possible stoppage of the hole through the screw 48 by particles of food. The connection fitting is preferably a die casting and has the end of a cover handle rod 56 cast therein as an insert.

A pivot bracket 58 is likewise preferably a die casting, cast about the rod 56 with the latter as an insert. The pivot bracket 58 has a downwardly extending toe portion 50 which projects into a tapped hole 62 formed in the socket boss 22, the toe portion 60 resting upon the end of a screw 64 which is threaded in the tapped hole 62. The cover handle rod 56 is provided with a molded plastic handle 66, the outer end of which is closed by a metallic cap 68 which may be pressed into the end of the handle 66. A latch '18 is freely pivoted on the cover handle rod 56, being constrained against movement longitudinally of the rod by the pivot bracket 58 and a sleeve III. The latch 18 has a hook portion 12 which may engage beneath the ferrule 28. The portion of the hook III which surrounds the rod 56 has knurling 13 formed thereon so as to make it possible conveniently to operate the latch hook by means of the thumb. The hook portion I2 of the latch engages the ferrule 28 in .a manner such that as the hook I is swung clockwise (Figure 4), the rod 56 will be pulled downwardly closer to the rod 36. The ferrule 28 is preferably knurled or otherwise serrated so as to prevent the hook portion 12 from slipping with respect the ferrule. The rod 56 is resilient and may be flexed slightly in bringing the latch hook I8 intoengagement with the ferrule 28.

The connection fitting 50 has a hollow stem -I4 threaded therein and extending vertically therefrom, the upper end of the stem forming a seat for a valve I6 formed at the end of a screw I8 which is threaded in a weight 80 and molded as an insert in a heat insulating knob 82. The weight 88 has a counterbore 84 which is of sufficiently great diameter, with respect to the outer diameter of the stem 14, to provide an annular ing flange 42 thereon.

The cover is made by stamping a circular blank from a sheet and forming the upwardly extend- The cover may then be formed by means of a press to assume the shape substantially of a portion of the surface of a sphere, as illustrated in Figure 2. After this operation, the flange 42 may be trimmed to the proper size, and the cover worked to a shape,

when unconstrained, as shown in Figures 6 and 7. To accomplish this latter working operation, the cover may be secured at its center to a rotating chuck, and have its peripheral edge portion engaged by a pair of non-rotating arms provided with contacting rollers by which pressure is applied at diametrically opposite sides of the convex surface of the cover. By this operation, the cover is progressively warped about diametrical axes until it assumes the warped shape shown in Figures 6 and 7 when it is unconstrained by any external forces. When in the latter shape, the closure approaches somewhat the-shape of a portion of a cylindrical surface.

Under these circumstances, the vertical projection of the cover is substantially in the form of an ellipse, indicated bythe line I00 of Figure 11, while the opening in the saucepan is shown as a circle 88. The vertical projection of the peripheral edge of the cover, as indicated by the line I80 (Figure 11), has a major axis which is greater in length than the diameter of the opening 88 and a minor axis which is less than the diameter of the opening 98. Because of this, the cover may be inserted through the opening 98 in the direction of its major axis until the leading edge of the cover abuts against the inner wall of the saucepan I4 directly beneath the guiding surface I6. Thereafter, the cover may be tilted so as to bring its edge completely within the saucepan I4 beneath the sealing surface 20. Then by raising the center of the cover, it will be guided by the guiding surface I6 into the position in which it is shown in Figure 2, with its gasket 44 in engagement with the seating surface 20, as shown in Figures 2 and 5. To raise the cover to this position, the toe B8 of the bracket 58 is inserted into the hole 62 in abutment with the end of the screw 64, and the handles 26 and 66 pressed together, thus applypassageway for the escape of steam. A pressure I indicating device 86 having an indicating pointer 88 cooperating with a notched indicating scale 90, is threaded in the connection fitting 50.

The cover 40 has a hole 92 punched therein to receive a pressure relief device 94 which may be made of a suitable heat, acid, and grease resistant rubber substitute. The device 94 is in the form of a plug having flanges 96 engaging opposite sides of the cover 48. The plug has sufllcient resiliency that it will be maintained in the aperture 92 unless the pressure within the saucepan I4 exceeds a predetermined maximum pressure. It will be seen from the drawings that the cover 40, when in operative position, is circular in shape and that the opening 98 formed in the top of the saucepan I4 is likewise circular in shape, but of substantially lesser diameter than I t e outside diameter of the cover 40. The cover ing an upwardly directed force to the center of the cover. The cover is then latched in position by swinging the latch hook I8, I2 clockwise to the position in which it is shown in Figure 4.

When the cover is in the unconstrained shape shown in Figures 6 and '7, the internal stresses are in equilibrium. After insertion of the closure within the container, the closure is brought into contact with the seating surface 28 along diametrically opposite portions of its peripheral edge. Thereafter, the handles 26 and 66 are pressed together to raise the central portion of the closure, and the extent to which the diametrically opposite portions of the closure are brought ,into contact with the seating surface 28 is progressively increased. As the closure is drawn against the seating surface, the force required to bring the edge of the closure into contact with the seating surface becomes less and less as the closure approaches its symmetrical unwarped shape in which the scaling is completed. As a result of applying the diminishing tributor of heat, while the stainless steel portion I I2 is highly resistant to attack by the acids and I being cooked.

pressure relief valve I6 from the end of the stem The steam pressure against the inside of the closure will increase the tightness of the seal at the surface 20 as the pressure increases. a result, a steam-tight seal between the cover and the saucepan is assured at all times.

If, through carelessness in. cleaning the cooker, the passageway through the stem 14 should become clogged, and thus prevent the operation of the pressure regulating valve 16, a dangerously high pressure mightbe built up within the saucepan were it not for the provision of the pressure relief device 94 which acts as a safety plug and is deformed and blown outwardly whenever the pressure within the saucepan exceeds the normal operating pressure by a predetermined amount.

In inserting the cover 40 in the saucepan, the guiding surface I and the centering surface I8 01 the saucepan serve the useful function of assuring that the cover will be accurately centered beneath the opening 98.

In Figure 8, I have shown a modified form of container in which the shell I02 is drawn from stainless sheet steel, the shell having a seating surface I04 for the closure and a centering cylindrical surface I06 to assure proper engagement of the peripheral edge of the cover with the seating surface I04. The upper end of the shell is provided with a finishing and reenforcing bead I08 which aids in strengthening the flange which provides the seating surface I04. A bottom III] is made of bi-metal consisting of a thin layer I I2 of stainless steel and a thick outer layer II4 of mild steel. The peripheral edge of the bottom has an upwardly directed flange IIIi into which the lower edge of th shell I02 telescopes, the shell and bottom being seam-welded together.

The container is provided with a handle socket I II, which may be an aluminum die casting having an' insert H8. The insert extends beyond the socket so as to provide an outwardly extending flange I which'is welded to the shell I02. Theremaining parts of the cooker are substantially identical with the construction previously described, and similar parts have therefore been designated by similar reference characters. difference between the two constructions resides,

.however, in the fact that in the construction of Figure 8 the gasket may, if desired, be omitted. Instead, the upwardlydirected peripheral flange I22 of the closure I24 has its upper edge rounded as indicated at I26 (Figure 10), and thus makes substantially a circular line contact with the seating surface I04. The closure I24 is sulficiently flexible that it will conform to slight irregularities in the conformation of the seating surface I04, and since the total force applied by the steam pressure to the cover is concentrated along the very limited area of contact between the closure and the seating surface I04, the unit pressure at the line of contact is very high. As

a result, the closure will form a steam-tight joint with the seating surface I04 ofthe shell.

other chemicals which may be present in the food The mild steel portion I I4 reenforces the layer of stainless steel H2 so that the bottom will be rigid and withstand the pressure to which it is subjected during use, without appreciable deformation. The outer surface of the bottom is preferably protected against corrosion by a suitable black finish to afford maximum heat absorption.

A gasket such as the gasket 44 not only serves as a means to facilitate the making of a pressuretight seal, but also provides electricalinsulation between the cover and the saucepan to prevent a corrosion of these parts by electrolysis. Since, in the construction shown in Figure 10, the cover and the container are of the same material, it is not essential to provide such electrical insulation between the two parts.

In the following claims it will be understood that in specifying the closure or cover to be in its operative shape" it is intended to refer to the shape of the closure as it is shown in Figs. 2 and 8, and, as a corollary, when its warped shape is specified, it is intended to refer to the shape in which the closure is shown in Figs. 6, 7, and 11, wherein the vertical projection (i. e., the projection, as seen in Fig. 11, on a plane perpendicular to the polar axis of the closure), has an overall dimension (the minor axis of its generally ellipti- .cal outline) which is sufficiently less than the diameter of the circular opening 00 (Fig. 11)

. same or equivalent means.

I claim; 1. An internal warpable resilient disc-like closure provided about its periphery with a seat engaging rim designed ,to make seating contact with a substantially plane and circular seat, the

III

The use of the bi-metal bottom III) has some I .material advantages in that the mild steel portion thereof acts as a good conductor and disinternal condition in the material of the body portion of said disc-like closure being such as to bring said closure when not subjected to external forces, into a warped shape having a major and a minor axis, the said minor axis being less than the diameter of the circular seat. whereby said disc may be passed freely through said circular seat, said disc-like closure being provided with means for applying and maintaining an external force thereto outwardly thereof to cause the closure to assume and maintain its operative shape with its peripheral rim in engagement with the aforesaid seat.

2. In a pressure cooker. the combination of a container having a circular opening therein and having an inwardly facing substantially plane seating surface surrounding said opening, a warpable resilient sheet metal closure having a circular peripheral edge engaging said seating surface to form a fluid-tight seal, and means to hold said closure against said seating-surface, said closure being internally stressed to cause it to assume a warped shape when free from external forces, said warped shape being one in which the distance between a pair of diametrically opposite points on the peripheral edge of the closure is appreciably less than the diameter of the opening in said container, whereby said closure when in its warped shape may be freely removed from and inserted into said container through the opening therein.

3. In a pressure cooker, the combination of a containerhaving a circular opening therein and having an inwardly facing substantially plane seating surface surrounding said opening, and a waipable resilient sheet metal closure provided with means about its periphery cooperable with said seating surface to form a fluid-tight seal, the internal stresses in said closure being such as to cause said closure to assume a warped shape when free from external forces, said warped shape being one in which the distance between a pair of diametrically opposite points on the periphery of the closure is appreciably less than the diameter of the opening in said container, whereby said closure when in its warped shape may be freely inserted and removed through the opening in said container.

4. The combination set forth in claim 3 in which manually operable means are provided for pulling the central portion of said closure out ward y with respect to said container when the closure is in its warped condition with portions of the peripheral edge thereof in engagement with said seating surface, whereby said application of force will cause said closure to conform to a shape in which its peripheral edge lies substan tially in a plane and in engagement with said seating surface.

5. The combination set forth in claim 3 in which a handle is attached to the central portion of said closure, means are provided for pivoting .said handle with respect to said container, and

including latching means for holding said handle in a predetermined position.

6. A closure for containers having circular openings surrounded by plane inwardly directed seating surfaces, comprising a warpable resilient disc-like sheet of metal provided about its periphery with a seat engaging rim for making sealing contact with the seatlngsurface on the container, the internal conditions inthe material of which the body portion of the closure is made being such as to bring said closure, when free from external forces, into a warped shape in which the distance between two diametrically opposite points on its periphery is appreciably less than the distance between diametrically opposite points spaced 90" from the first named points, and is also appreciably less than the diameter of the container opening to be closed,

whereby said closure may be passed freely through the opening in the container and by applying an external force to said closure, the internal conditions which cause warping of the closure maybe overcome and its peripheral edge may be brought into a plane circular shape of greater diameter than that of the opening in the containen '7. A pressure cooker comprising-a, container having a substantially circular opening formed therein and having an annular inwardly facing seating surface surrounding said opening, and a resilient sheet metal closure substantially circular when in operative shape and of diameter materially greater than that of said opening. said closure being sumciently elastic to warp without xceeding its elastic limit to a shape in which the vertical projection of its periphery has a dimension substantially less than the diameter of said opening, and cooperative means acting between said container and said closure to maintain said closure in its operative shape with its periphery in sealing engagement with said seating surface.

8. An internal warpable resilient disc-like closure when in its operative shape having a periphery cooperable with a plane seating surface, said closure being subjected to internal forces which warp it to a shape in which the distance between diametrically opposite points on its periphery in one direction is considerably less than the distance between diametrically opposite points on its periphery in a direction perpendicular to said first direction, the internal forces in said closure being such that by application of an external force it may readily be deformed to an operative shape in which its peripheral edge lies in a circular plane.

9. In a pressure cooker, the combination of a container having a circular opening therein and having an inwardly directed plane seating surface surrounding the opening, a resilient sheet metal closure for said opening, said closure being subjected to internal stresses in such manner that it may assume a warped shape in which the internal stresses are in equilibrium and may assume an operative shape in which its peripheral edge is circular in shape and in which the internal stresses are in substantial equilibrium, whereby when said closure is in its warped shape it may be freely inserted through said opening so as to have portions of its peripheral edge engage said plane seating surface and when sub- Jected to an external force its entire peripheral edge will engage said seating surface to make sealing contact therewith, and means for applying said external force to the central portion of said closure.

10. The combination set forth in claim 2 in which said closure has an outwardly directed flange at its peripheral edge.

'11. The combination set forth in claim 2 in which said closure is dished and surface facing outwardly.

' 12. The combination setv forth in claim 2 in which a gasket is provided between the peripheral ,edge of said closure and the seating surface to seal the connection and to provide electrical insulation between the closure and the container.

13. The combination set forth in claim 2 in which the means to hold said closure against saidseating surface consists of manually operable slightly resilient means for applying an outwardly directed force substantially centrally of the closure.

14. The combination set forth in claim 2 in which the means for holding the peripheral edge of the closure against said seating surface comprises a handle having its end secured to said applies an outwardly directed force to'the closure at substantially the center thereof.

15. The combination set forth in claim 2 in which the means to hold theperipheral edge of the closure against said seating surface includes a manually operable member, and means to hold said member in position applying an outwardly directed force to said closure at substantially the center thereof.

16. The combination set forth in claim 2 in has its convex v which said container is provided with a radially outwardly extending handle, and in which the means for holding the peripheral edge portion of the closure against said seating surface includes a slightly yieldable handle attached to said closure substantially at the center thereof, extending in a direction generally parallel to the container handle and provided with a pivot intermediate its ends cooperable with the container, and means are provided to hold said handles in substantially fixed position with respect to each other.

1'7. The combination set forth in claim 2 in which a fitting having a passageway extending therethrough is attached to said closure at sub--. stantially the center-thereof, and in which the means for holding the closure against the seating surface includes means connected to said fitting for exerting an outwardly directed force upon said closure suflicient to flex said closure and cause its peripheral edge portion to seat against said seating surface, and a pressure controlling device is secured to said fitting and communi cates with the passageway therethrough.

18. In ai pressure cooker, the combination of a container having an opening formed in the top thereof and having an inwardlyfacing flat seating surface surrounding said opening and a centering wall of generally cylindrical shape surrounding said seating surface, and a closure of flexible sheet metal having its peripheral edge engaging said seating surface and prevented from moving laterally from said seating surface by said centering wall.

19. In combination, a container having a substantially circular opening therein, a cover adapted to be inserted into said container through said opening, said cover being normally warped so that its projection on a horizontal plane is substantially an ellipse, the minor axis of which is less than the diameter of said opening in the container, and means operable after the cover has been placed in said container for applying an outwardly directed force to said cover at approximately the center thereof, said cover being so conformed that upon application of such external force it will be deformed into a circular shape.

20. A closure for a circular opening in a con 'tainer comprising a flexible resilient dished metallic circular sheet internally stressed so as a container having an inwardly extending annular flange at the top thereof, a closure for the circular opening in said flange, said closure being circular when in its operative shape but being normally warped by the internal stresses therein to a shape enabling its free insertion into said container through said opening despite the greater diameter of the closure, and means to pull the peripheral edge of said closure into sealing contact with the inner surface of said flange.

24. In a pressure cooker, the combination of a generally cylindrical container having a substantially circular opening at its top, said opening being of diameter less than that of the container directly beneath the top, said container having an inwardly facing plane seating surface around said opening, a dished circular cover formed of thin resilient sheet metal of diameter greater than that of said opening, said cover having a peripheral flange but being internally stressed so as normally to assume a sufliciently warped shape that it may be easily inserted in said container through said opening, and means to apply an outwardly directed force to substantially the center of said cover thereby to pull the entire peripheral flange of said cover into sealing contact with the seating surface of the top of said container.

25. In a pressure cooker, the combination of a generally cylindrical container having a substantially circular opening at its top, said opening being of diameter less than that of the container. directly beneath the top, said container having an inwardly facing plane seating surface around said opening, a dished circular cover formed of thin elastic sheet metal of diameter greater than that of said opening, said cover to assume a warped shape when not subjected to external stresses, said closure being sufficiently elastic that it may be forced into its circular shape without exceeding the elastic limit of the metal of which it is made.

21. A closure for circular openings in containers comprising a circular sheet of flexible metal of diameter appreciably greater than that of the opening to be closed, said sheet, when in operative position closing said opening, having a form defined by substantially parallel surfaces of revolution, and containing internal stresses capable of causing it to warp, when not constrained by external forces, to a shape in which it may be freely inserted in said opening.

22. In combination, a container having a wall with a circular opening therein, and a circular sheet metal closure for said opening of greater diameter than said opening, said closure being normally held against the inner surface of said wall and when unconstrained being deformed by internal forces to a shape permitting its free,

removal from the container through said opening. 23. In a pressure cooker, the combination of having a peripheral flange but being internally stressed so as normally to assume a sufficiently warped shape that it may be easily inserted in said container through said opening, and means to apply an outwardly directed force to substantially the center of said cover thereby to pull the entire peripheral flange of said cover into sealing contact with the seating surface of the top of said container, said means comprising a pair of handles,'one secured to said container and the other secured to said cover, means intermediate the ends of one of said handles to hold said handles separated, and interengaging latching means to hold said handles together.

26. In a pressure cooker, the combination of a container having a circular opening surrounded by an internal inwardly facing seating surface, a handle secured to said container, a fulcrum associated with said handle, a flexible closure for said containerof shape similar to that of said open ing but having each major dimension greater than the corresponding dimension of the opening, said cover being capable of warping along a diameter thereof to an extent sufficient to permit free insertion of said cover into said container, a handle secured to the center of said cover and having a part engaging said fulcrum, said handle extending generally perpendicular to the diameter of the cover along which it warps,

and latching means on said handles whereby said closure handle may be latched in position to hold said closure in operative position with its peripheral edge in engagement with said seating surface.

27. A normally warped elastic flexible sheet metal closure, internally stressed when constrained in dished operative position and which, when unconstrained, resumes its predetermined 1 said closure is insertable only when it is in its warped shape, and means for applying a pulling force to the central portion of said closure while portions of the periphery thereof are in engagement with the internal surface of the container adjacent its opening, thereby to cause the entire peripheral edge 01' the closure to be drawn into sealing engagement with said surface of said container.

30. In a pressure cooker, the combination of a container having a circular opening therein and having an inwardly facing substantially plane seating surface surrounding said opening, a

warpable resilient sheet metal closure having a circular peripheral edge engaging said seating surface to form a fluid-tight seal when in closing position, and means to apply a force outwardly on said closure to hold it against said seating surface, said closure being internally stressed to cause it to assume a warped substantially elliptical shape when freed from external forces and in its inoperative shape, said warped shape being one in which the distance between a pair of diametrically opposite points on the peripheral edge of the closure is appreciably less than the diameter of the opening in said container, whereby said closure when in its warped shape may be freely removed from and inserted into said container through the opening therein.

31. A closure for a circular opening in a container comprising a flexible resilient dished metallic circular sheet internally stressed so as to assume a warped shape substantially along a diametral line when not subjected to external stresses, said closure being sufiiciently elastic that it may be forced into its circular shape without exceeding the elastic limit of the metal of which it is made.

ALFRED VISCHER, JR.

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