BACKGROUND OF THE INVENTION1. Field of the Invention[0001]
The present invention relates to a pressure cooker and more specifically, to a pressure cooker with a safety cap that covers and protects the pressure release valve.[0002]
2. Prior Art[0003]
A pressure cooker is a cooking utensil (pot) that utilizes high-temperature and high-pressure steam to cook food inside the pot. The pot and its lid are designed to create an airtight space inside the pot. When the pot is heated, the air inside expands. The expanding air inside the pot is unable to escape, so the atmospheric pressure within the pot increases. As the atmospheric pressure increases, the boiling point of water also increases. Thus, a pressure cooker enables the water or moisture in the pot to become hotter than it would under normal atmospheric pressure.[0004]
With a conventional cooking pot, the water inside a pot turns into steam at around 100° C. (212° F.). The steam freely escapes the pot, leaving the atmospheric pressure within the pot close to normal and the temperature close to 100° C. Consequently, a large portion of the heating energy applied to the pot is wasted in warming the surrounding air.[0005]
In addition to creating a high-pressure environment within a pot, a pressure cooker also makes the water in a pot, in addition to the moisture within food, hotter than 100° C. and this impacts cooking in three ways. First, food cooks much faster in a high-pressure and high-temperature environment, and requires far less cooking or heating time. The cooking time is shortened to one-third or one-fourth of the time required for a conventional cooking pot. Second, the decreased cooking time and trapped steam results in greater energy efficiency. A pressure cooker generally requires only one-fourth to one-third of the energy of a conventional cooking pot. Third, high-temperature and high-pressure cooking significantly improves cooking in high altitudes and in cold climates.[0006]
Unfortunately, there is an omnipresent risk of explosion caused by too much pressure inside the pot. This risk is very real because a pressure cooker prohibits the free circulation of air between the interior and the exterior of the pot and cooks food under high-pressure and high-temperature conditions. Present pressure cooker manufacturers alleviate this risk in many ways, including: using sturdier materials to construct pots; utilizing a timer to control the length of heating time; installing a pressure gauge to monitor the atmospheric pressure inside; and installing a pressure release valve, which is the most widely used method.[0007]
A pressure release valve is a device that is physically attached to a pressure cooker. Its function is to release the pressurized air in a pot when the atmospheric pressure within the pot exceeds a pre-set point. The valve is usually installed in the pressure cooker lid. The interior portion of the valve is shaped like a pipe and it has a closed end surrounded by four or five air intake apertures of 1 mm to 2 mm in diameter. The exterior portion of the valve is an air release nozzle. This nozzle is kept closed by the pressure of a weight device or a spring mechanism. When the pressure of the air or steam coming into the valve becomes greater than the pressure that keeps the nozzle closed, the valve opens and releases the inside air, which reduces the atmospheric pressure within the pressure cooker.[0008]
While this type of safety device is very widely used, it is flawed in two major ways. First, the air intake apertures are easily clogged. When this occurs, the expanding air inside the pot has no means of release and the atmospheric pressure rises, which significantly increases the risk of explosion. The air intake apertures may be clogged by foods while cooking or by inadequate cleaning.[0009]
Second, putting aside the safety function that the valve actually provides, the valve's exterior appearance does not give the user an adequate sense of safety in using the pressure cooker. When a user sees only four or five very small clog-prone apertures (the number and size of the apertures vary according to size and type of the pressure cooker), he or she may feel more anxious than assured of the valve's safety. As if to increase this insecurity, the owner's manual accompanying the pressure cooker, in addition to other literature, repeatedly warn users about the importance of proper maintenance of the valve. While many consumers may realize the merits of a pressure cooker, unfortunately, they largely remain potential users.[0010]
SUMMARY OF THE INVENTIONThe two objectives of the present invention are to provide a significantly safer pressure cooker by protecting the pressure release valve so that it will not clog, thereby preventing explosions caused by clogging, and to eliminate a user's insecurity regarding the proper functioning of the pressure release valve.[0011]
The basic idea of the present invention is to prevent food particles from reaching the pressure release valve during cooking, so that the air intake apertures cannot be clogged.[0012]
The objectives are accomplished by an innovative and unique device specifically designed for a pressure cooker, which protects air intake apertures and prevent clogging.[0013]
More specifically, a wavy mesh-like or perforated surface structure (hereinafter referred to as “safety cap”) is installed around the pressure release valve of the pressure cooker. By design, the safety cap has numerous holes that are slightly smaller or equal to the size of the air intake apertures. During cooking, the hot air or pressure inside the pressure cooker is allowed to escape when it is appropriate, while the safety cap catches food particles that may clog the air intake apertures. The sheer number of holes and the size of those holes in the surface of the safety cap greatly improves the means by which steam may escape while preventing food from reaching the air intake apertures entirely, thus protecting the pressure release valve so that it may serve its safety function.[0014]
BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 illustrates a pressure cooker to which the present invention is applied;[0015]
FIG. 2 shows in partial cross section how the snap-fit safety cap attaches using elastic material in the present invention;[0016]
FIG. 3 shows in partial cross section how the screw safety cap attaches in the present invention;[0017]
FIG. 4 shows in partial cross section how the safety cap attaches to the pressure cooker lid in the present invention;[0018]
FIG. 5 shows in cross section the detail of how the screw safety cap attaches to the pressure cooker lid in the present invention;[0019]
FIG. 6 shows in cross section the detail of how the snap-fit safety cap attaches to the pressure cooker lid in the present invention;[0020]
FIG. 7 shows in partial cross section how the screw safety cap with its wavy mesh casing body attaches to a specialized lid chamber in the present invention;[0021]
FIG. 8 shows in cross section the detail of how the screw safety cap attaches to the specialized lid chamber in the present invention; and[0022]
FIG. 9 shows in cross section the detail of how the snap-fit safety cap attaches to the specialized lid chamber in the present invention.[0023]
DETAILED DESCRIPTION OF THE INVENTIONThe safety cap of the present invention (See FIG. 1) is used in an[0024]ordinary pressure cooker10 that includes apot12, alid14 and a pressure regulator orpressure release valve16 that releases the pressure (heated or hot air) inside thepot12 during cooking. Thepressure release valve16 is provided at the center of thelid14 and is manufactured with a pressure release passage (not shown).
More specifically, the[0025]pressure release valve16 comprises of anupper portion16a, which is exposed outside thelid14 and has apressure regulation weight17, and alower portion16b, which is located under thelid14 and is covered by asafety cap20 described below. Thelower portion16bof thepressure release valve16 displays some air intake apertures18 (for instance, one aperture is opened in the lower end surface of thepressure release valve16, and four apertures are opened in the peripheral area near the lower end of thepressure release valve16; however, only one aperture is shown in FIG. 1). Theseair intake apertures18 communicate with, via the pressure release passage (not shown), an air release aperture (not shown) opened in theupper portion16aof thepressure release valve16. Thus, hot air and the pressure inside thepressure cooker10 during the cooking is released through theair intake apertures18 and the pressure release aperture.
There are three main installation methods for the present invention: 1) direct attachment to the pressure release valve, 2) direct attachment to the pressure cooker lid, and 3) attachment to a specialized lid chamber. Each method also offers the option of a snap-fit or screw installation. The following is a brief description of each method.[0026]
Method 1: Direct Attachment to the Pressure Release Valve[0027]
Snap-Fit Attachment to the Pressure Release Valve (See FIG. 2)[0028]
The[0029]safety cap20 is a detachable cover that attaches to thelower portion16bof thepressure release valve16.
As seen in FIG. 2, the[0030]safety cap20 is comprised of amesh casing body30 with numerous openings and anattachment frame40 that is fixed to the top ofmesh casing body30. Theattachment frame40 is located at the center of the top surface of themesh casing body30. Themesh casing body30 and theattachment frame40 are both made of heat resistant material such as metal (e.g. stainless steel) and/or heat-resistant plastics that can withstand the high-temperature and high-pressure inside thepressure cooker10. They are also formed rigid to avoid deformation that may be caused by high heat and high pressure during cooking. Each of the openings in themesh casing body30 is equal to or smaller than theair intake apertures18 of thepressure release valve16.
The[0031]mesh casing body30 is comprised of a shallow top section30a, which is in a conical shape and a relatively deep main section30b, which is in a reversed conical shape. The lower edge of the top section30aand the upper edge of the main section30bare connected and form themesh casing body30 with acircumferential ridge32. Themesh casing body30 has a diameter that is three times larger than that of thepressure release valve16 of thepressure cooker10. In addition, the depth or the height of themesh casing body30 is designed to be greater than the length of thelower portion16bof thepressure release valve16. As a result, when thesafety cap20 is set so that it covers thepressure release valve16, there is space between the inner surface of themesh casing body30 and the outer surface of thepressure release valve16.
The[0032]attachment frame40 includes anelastic ring44 in its interior. The inner diameter of theelastic ring44 is the same as (or slightly smaller than) the outer diameter of thelower portion16bof thepressure release valve16 of thepressure cooker10. Theelastic ring44 is made of elastic material and the rest of theattachment frame40 is made of rubber or another heat resistant elastic material.
The[0033]safety cap20 is attached to thepressure release valve16 by pushing or sliding on theattachment frame40 of thesafety cap20 to thelower portion16bof thepressure release valve16. Theattachment frame40 has theelastic ring44 inside it, so that theattachment frame40 fits on thelower portion16bof thepressure release valve16.
A[0034]circumferential groove16con the outer surface of thepressure release valve16 ensures that theattachment frame40 itself and theelastic ring44 are snugly fitted in thisgroove16c. The result is that thesafety cap20 is securely attached to thepressure release valve16.
Great care should be taken when attaching the[0035]safety cap20 to thepressure release valve16. The attachment rim40 (or the elastic ring44) should not cover or close thepressure intake apertures18 of thepressure release valve16.
With the[0036]safety cap20 attached to thepressure release valve16, themesh casing body30 of thesafety cap20 catches fine food particles that may block theair intake apertures18 during cooking. Thus, theair intake apertures18 of thepressure release valve16 are prevented from clogging by food particles. The surface area of thesafety cap20 is substantially greater than thelower portion16bof thepressure release valve16 and in particular, greater than theair intake apertures18. Therefore, it is nearly impossible for all the openings of thesafety cap20 to be clogged entirely since cooking will normally be over before the entire surface of thesafety cap20 is covered by food particles. Because thesafety cap20 is rigid and because it covers theair intake apertures18, the pressure release valve is prevented from clogging.
Screw Attachment to the Pressure Release Valve (See FIG. 3)[0037]
The[0038]safety cap20 can also be mounted on the pressure release valve by making theattachment frame40′ internally threaded, so that it is screw-engaged with a thread16dformed on the external surface of thepressure release valve16.
By screwing the[0039]attachment frame40′ to thepressure release valve16, the safety cap20 (which is a semi-sphere shape in FIG. 3), like thesafety cap20 shown in FIG. 2, is attached to thepressure release valve16 with a space between the external surface of thepressure release valve16 and the inner surface of thesafety cap20′, so that thepressure release valve16 is not in contact with thesafety cap20′ when thesafety cap20′ is screwed to thepressure release valve16.
Method 2: Direct Attachment to the Pressure Cooker Lid[0040]
Screw Attachment to the Pressure Cooker Lid (See FIGS. 4 and 5)[0041]
In the structures shown in FIGS. 4 and 5, the[0042]safety cap20″ (only a part of it is shown) is comprised of acircular attachment frame40′ and amesh casing body30′ with its circumferential edge secured by theattachment frame40′. Theattachment frame40′ is formed on its outer circumferential surface, with anexternal screw thread40s. Thelid14 of the pressure cooker is formed on its undersurface with a ring-shapedridge14aso that it surrounds thepressure release valve16. The ring-shapedridge14ais formed on its inner circumferential surface with aninternal screw thread14s. The inner diameter of the ring-shapedridge14aof thelid14 and the outer diameter of theattachment frame40′ are the same. Themesh casing body30′ has a convex shape, so it will not come in contact with thepressure release valve16 when thesafety cap20″ is attached to thelid14.
With the structure described above, the[0043]safety cap20″ is attached to the under surface of thelid14 by screwing theattachment frame40′ of thesafety cap20″ to the ring shapedridge14aof thelid14. Thelower portion16bof thepressure release valve16 is covered by thesafety cap20″, and theair intake apertures18 of thepressure release valve16 are prevented from clogging.
Snap-Fit Attachment to the Pressure Cooker Lid (See FIGS. 4 and 6)[0044]
Instead of internal-[0045]thread14s, in the structure shown in FIG. 5, theattachment frame40″ of thesafety cap20″ is made of an elastic material. A curved outer circumferential surface and an internalcircumferential groove14gwhich holds the curved outer circumferential surface of theattachment frame40′″ fits snugly into the internal lower edge area of thedomed portion14bof thelid14. Theattachment frame40″ of thesafety cap20″ that includes themesh casing body30′ has an outer diameter that is the same as the inner diameter of thecircumferential groove14gof the ring-shapedridge14aof thelid14.
By pushing the[0046]attachment frame40″ into thecircumferential groove14gof the ring-shapedridge14aof thelid14, theattachment frame40″ is snap-fitted into thecircumferential groove14gof the undersurface of thelid14. Thesafety cap20″ is thereby attached to thelid14, and the pressure release valve16 (or thelower portion16bhaving the pressure intake aperture18) is covered by thesafety cap20″.
Method 3: Specialized Lid Chamber[0047]
Screw Attachment to the Specialized Lid Chamber (See FIGS. 7 and 8)[0048]
In the structure shown in FIGS. 7 and 8, the[0049]safety cap20′″ is comprised of acircular attachment frame40′″ and amesh casing body30″, with its circumferential edge secured by theattachment frame40′″. The outer circumferential surface of thecircular attachment frame40′″ is made with theexternal thread40s. Themesh casing body30″ is made of a wavy mesh plate comprised of numerousflat sections30cthat are connected bynumerous ridge portions30d. Thelid14 of the pressure cooker is formed with an outwardly expanding dome-shapedportion14bwith thepressure release valve16 at the center; and aninternal screw thread14sis formed in the interior lower edge area of the dome-shapedportion14b. The inner diameter of the interior lower edge area of the dome-shapedportion14bof thelid14 and the outer diameter of theattachment frame40′″ of thesafety cap20′″ are the same.
The[0050]safety cap20′″ is mounted on the under surface of thelid14 by screwing theattachment frame40′″ of thesafety cap20′″ to the inside of the dome-shapedportion14bof thelid14. Thelower portion16bof thepressure release valve16 is covered by thesafety cap20′″, and this prevents the air intake apertures of thepressure release valve16 from clogging. Because of its dome-shapedportion14b, thesafety cap20′″, and themesh casing body30″ that is formed by the wavy mesh plate, which is comprised of the numerousflat sections30c, avoids contact with thepressure release valve16.
Due to the ridged[0051]portions30d, food particles are less likely to be caught by thesafety cap20′″, but some of them are still caught by theflat sections30c. Themore ridges portions30 thesafety cap20′″ has, the more food particle are caught or trapped by thesafety cap20′″; consequently, thesafety cap20′″ prevents any clogging of thepressure release valve16.
Snap-Fit Attachment to the Specialized Lid Chamber (See FIGS. 7 and 9)[0052]
The[0053]safety cap20 can also be installed by a snap-fit attachment to the specialized lid chamber. More specifically, in the structure shown in FIG. 9, theattachment frame40″″ of thesafety cap20′″ is made of an elastic material. It has a curved outer circumferential surface and an internalcircumferential groove14g′, which snugly fit the curved outer circumferential surface of theattachment frame40″″, which is formed in the internal lower edge area of thedomed portion14bof thelid14. Theattachment frame40″″ of thesafety cap20′″ that includes themesh casing body30″ has the same outer diameter as the inner diameter of the internal lower edge area of thedomed portion14bof thelid14.
By pushing the[0054]attachment frame40″″ of thesafety cap20′″ into thecircumferential groove14g′ of thelid14, theattachment frame40″″ is snap-fitted into thecircumferential groove14g′. Thesafety cap20′″ is thereby attached to thelid14, and thepressure release valve16 is covered by thesafety cap20′″.
In the illustrated structures, the attachment frame[0055]40 (40′,40″,40′″,40″″) is in a circular shape; however, it can also take other shapes such as a square, rectangle or oval.
The safety cap[0056]20 (20′,20″,20′″) in the figures has a curved surface; however, it can also have a planar surface by making the safety cap20 (particularly, the mesh casing body30 (30′,30″) in a pyramid or triangular pyramid.
Lastly, by making the[0057]attachment frame40 of thesafety cap20 with a magnetic material, thesafety cap20 can be magnetically mounted to the undersurface of thelid14. When theattachment frame40 is made with a magnetic material such as carbon core stainless steel, then screw-mounting or snap-fit mounting are unnecessary.