WO1991012757A1

WO1991012757A1 - Microwave brewing apparatus control valve and method of making a beverage

Info

Publication number: WO1991012757A1
Application number: PCT/CA1990/000060
Authority: WO
Inventors: Dong Yu
Original assignee: Micro Cafe Inc.
Priority date: 1990-02-23
Filing date: 1990-02-23
Publication date: 1991-09-05

Abstract

A method of making a beverage from an infusible material in a microwave oven, employing an apparatus having a microwave transparent pressurizable liquid reservoir, said pressurizable liquid reservoir having as valve to release fluid, means to control the rate of release of gas and fluid from the pressurizable liquid reservoir, said pressurizable liquid reservoir being mounted in fluid communication with a filter chamber, said filter chamber mountable above a beverage receptacle, the method comprising placing a supply of an infusible material in the filter chamber, mounting said filter chamber on a receptacle, pouring a liquid into the pressurizable liquid reservoir to a level below the top of the pressurizable liquid reservoir, securing the lid to the pressurizable liquid reservoir, mounting the pressurizable liquid reservoir in fluid communication with the filter chamber, adjusting the control means to control the rate of release of fluid from the pressurizable liquid reservoir, heating said liquid in said pressurizable liquid reservoir with microwave energy to raise the liquid vapor pressure in the pressurizable liquid reservoir sufficiently to move said valve sufficiently to open the lower valve and force said liquid from the pressurizable liquid reservoir through the lower valve into the filter chamber to make a beverage, and collecting the beverage in said receptacle.

Description

Mi rowave brewing apparatus control valve and method of making a beverage

BACKGROUND OF THE INVENTION

This invention relates to an apparatus for brewing coffee, tea or other beverages from respective infusible materials using microwave energy, and to a method of making such beverages. More particularly this invention relates to a valve for controlling the rate at which fluid flows through the infusible material. In Canadian Patent Application Number 591,303-7 filed on February 16, 1989 entitled "Microwave Brewing Apparatus and Method" I disclosed an apparatus comprising a pressurizable water reservoir and a filter chamber disposed below the reservoir. The reservoir was provided with pressure overflow means which, in operation, prevented water in the reservoir from overflowing into the filter chamber until vapor pressure in the reservoir was built up due to the influx of microwave energy to form steam so as to force the heated water to overflow into the filter chamber to mix with the infusible material, e.g. ground coffee, to make a beverage. The present invention relates to an improvement in my above noted invention and more particularly to the addition of a control valve- to control the flow of fluid through the overflow means to the filter chamber to control the concentration of infusible material in the drink.

Microwave coffee makers are known in the art. U.S. Patent No. 4,104,957 issued to Freedman et al. discloses a drip-type appliance containing a thermally controlled valve in a microwave transparent water reservoir which is positioned over a coffee compartment which in turn is placed above a receptacle. For use, the reservoir is filled with an amount of water, ground coffee is placed on the filter in the coffee compartment, the appliance is placed in a microwave oven and the oven is operated for a selected period of time. When the temperature of water reaches a predetermined level, the valve opens allowing the heated water to flow down through the coffee grounds. U.S. Patent No. 4,381,696 issued to Koral proposes a similar solution except for the valve between the water reservoir and the coffee compartment being manually operated. After water has been placed in the reservoir, the valve is opened manually immediately before or during the activation of the microwave oven with the coffee maker disposed therein.

U.S. Patent No. 4,386,109 issued to Bowen et al. teaches an expresso-type coffee maker for use in a microwave oven. Water is stored in a microwave transparent reservoir which is separated from a receptacle by a layer of coffee grounds placed over a strainer. The coffee layer is compressed and forms a pressure resistant seal over the water outlet from the reservoir. When the water in the reservoir is heated by microwave energy the pressure in the reservoir rises to a level sufficient to force steam and water through the coffee layer into the receptacle.

Another drip-type coffee maker is described in U.S. Patent No. 4,577,080 to Grossman. The maker comprises a water container positioned above a coffee compartment which is separated from the container by a partition. The partition has perforations sealed with a thermally responsive material that melts when the water is heated to the desired temperature in the microwave oven, allowing the heated water to flow from the upper reservoir through the coffee grounds into a receptacle placed below the coffee maker.

The latter design is apparently intended to be a disposable coffee maker.

It will be appreciated that these and similar microwave coffee makers can be designed to prepare small quantities of coffee, such as a single cup, or to brew larger quantities. In any case, their dimensions, of course, must be such as to allow the appliances to be accommodated in an average microwave oven.

While the above-described microwave coffee makers are useful, there is still a need for a simple and reliable drip-type brewing appliance for use in a microwave oven, an appliance employing a simple control valve to control the flow of fluid through the infusible material and thus control the concentration of infusible material in the drink.

STATEMENT OF THE INVENTION

According to the present invention, there is provided an apparatus for brewing coffee, tea or a similar beverage from a respective infusible material, i.e. ground coffee beans, tea leaves, etc., using a typical microwave oven.

The apparatus is comprised of a receptacle, adapted to receive the final liquid product; a filter chamber adapted to receive infusible material, i.e. ground coffee beans, tea leaves etc. placed over the receptacle; a pressurizable liquid reservoir to retain the liquid which is to be pushed by vapor pressure through the filter chamber into the receptacle and a reciprocating control valve to control the flow of steam out of the top of the pressurizable liquid reservoir and liquid out of the bottom outlet of the pressurizable liquid reservoir into the filter chamber and subsequently into the receptacle. The pressurizable liquid reservoir is made of microwave transparent material so as to allow the fluid in the pressurizable liquid reservoir to be readily heated.

The pressurizable liquid reservoir includes a gas valve at the top and a liquid outlet valve. A reciprocating control valve, comprised of a valve shaft having one upper valve head at the top and a second lower valve head on the bottom of the valve shaft, is biased in a downward closed position by a spring such that the upper valve head and the lower valve head are both seated when the liquid in the pressurizable liquid reservoir is not boiling sufficiently to create a pressure to overcome the downward bias created by the spring. The tension on the spring biasing the reciprocating valve downwardly may be adjusted by a knob to control the extent of reciprocation of the reciprocating valve which in turn controls the manner and rate of flow of liquid through the filter chamber.

In operation, the filter chamber is placed on the cup or beverage receptacle, a supply of infusible material is placed in the filter chamber, the

^"pressurizable liquid reservoir is mounted over the filter chamber, liquid is poured into the pressurizable liquid reservoir to a level below the top of the pressurizable liquid reservoir, the pressurizable liquid reservoir is closed, the liquid in said pressurizable liquid reservoir is heated with microwave energy to raise the vapor pressure in the pressurizable liquid reservoir sufficiently to cause the reciprocating valve to move upwardly forcing liquid through the bottom outlet of the pressurizable liquid reservoir.

If the adjustment of the spring biasing the reciprocating valve downwardly creates a light bias pressure, the vapor pressure will cause the reciprocating valve to move upwardly against the spring sufficiently to release gas through the valve at the top of the pressurizable liquid reservoir. When the downward pressure exerted by the spring overcomes the vapor pressure caused by release of steam from the top valve of the pressurizable liquid reservoir, the valve will seat in both the top and bottom valve seats until the vapor pressure increases sufficiently to raise the valve stem and release liquid through the valve in the base of the pressurizable liquid reservoir into the filter chamber. A light adjustment of the downward bias of the spring causes a reciprocating motion of the valve stem resulting in an intermittent release of liquid from the pressurizable liquid reservoir to the filter chamber. The intermittent release of liquid through the filter chamber results in a stronger drink. If the adjustment of the spring biasing the reciprocating valve downwardly creates a large bias pressure, the reciprocating movement of the valve stem is reduced. Liquid is released through the infusible material more rapidly resulting in release of less infusible material and a lighter drink.

The valve stem includes an upper and lower valve head. However the upper movement of the valve stem does not open both the upper gas valve and the lower liquid valve at the same time. The lower valve seat releases liquid from the pressurizable liquid reservoir immediately upon upper movement of the valve stem. The upper valve head remains in contact with the bottom portion of the upper valve seat during the initial upper movement of the valve stem and only releases gas through the upper valve after further upper movement of the valve stem than that required to release liquid through the lower valve of the pressurizable liquid reservoir. In one embodiment of the pressurizable liquid reservoir the outlet in the base of the pressurizable liquid reservoir is extended upwardly above the normal water level of the reservoir by a tube integral with the bottom of the pressurizable liquid reservoir. The lower valve head closing off the opening at the top of the tube is a flange on the bottom of the valve shaft. A tube integral with the outside of the flange at the bottom of the valve shaft extends downwardly concentrically about the central upstanding outlet tube to a point near the bottom of the pressurizable liquid reservoir.

A second embodiment of the pressurizable liquid reservoir features a central opening in the bottom of the pressurizable liquid reservoir with no upstanding tube. The reciprocating valve shaft extends all the way to the bottom of the pressurizable liquid reservoir. The lower valve head is connected to the bottom of the valve shaft to close off the liquid opening in the bottom of the pressurizable liquid reservoir except when heat is generated to create sufficient vapor pressure to cause the valve shaft to move upwardly to release liquid from the bottom of the pressurizable liquid reservoir.

In each embodiment the receptacle and filter chamber may be identical. The difference in the two embodiments illustrated resides in a different arrangement within the pressurizable liquid reservoir requiring a different design of the reciprocating control valve which controls the venting of gas through the top of the pressurizable liquid reservoir and the flow of liquid through the bottom outlet of the pressurizable liquid reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings which illustrate embodiments of the present invention, Figure 1 is a vertical sectional view of one embodiment of the apparatus,

Figure 2 is a vertical sectional view of a second embodiment of the pressurizable liquid reservoir,

Figure 3 is a top view of the knob used to control the liquid flow through the pressurizable liquid reservoir.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings in which like numerals correspond to like parts or elements, the apparatus of the present invention comprises a pressurizable liquid reservoir 10 and a filter chamber 12. The pressurizable liquid reservoir 10 has a matching twist-closure lid 14 which ensures virtually hermetic closure of the pressurizable liquid reservoir 10. To facilitate its handling, the lid 14 has a number of ribs 16 on its external peripheral surface.

Threads 18 of the interior wall of the lid 14 serve to engage the lid 14 with threads 20 on the exterior of the pressurizable liquid reservoir 10.

Referring particularly to Figure 1, the pressurizable liquid reservoir 10 has an inclined wall 11 extending downwardly from the base to receive the filter chamber 12. The inner wall 11 may provide frictional engagement with the wall of the filter chamber 12, as shown in Figure 1, or a threaded connection may be employed, using threads 24 and 26 not shown. The pressurizable liquid reservoir 10 is supported on receptacle 38. The filter chamber 12 has a concave bottom 32 with a metal filter 34 molded thereinto. The metal filter 34 has perforations of a size adapted to retain the particles of an infusible material, e.g. coffee grounds, and to allow the passage of a liquid therethrough. The filter chamber 12 also has a peripheral wall 36 of a size adapted to frictionally engage most of inclined wall 11 extending downwardly from the base of pressurizable liquid reservoir 10. It is preferable to provide a small passage 39 between the receptacle 38 and the outward extension 40 at the base of pressurizable liquid reservoir 10 for excess steam to escape. The small passage 39 may be at a point or points in the outward extension 40 of the base of filter chamber 12. An annular lip 41 is provided on the underside of the pressurizable liquid reservoir 10, which serves to locate the filter chamber 12 on the receptacle 38. The concavity of the bottom of the filter chamber 12 helps to keep the flow of liquid from the chamber close to the centre of the filter.

The filter chamber and pressurizable liquid reservoir may be used with any receptacle 38. It is preferable, however, that the receptacle 38 is of a microwave transparent variety. As shown in Figure 1 the bottom of the reservoir 10 includes a central downward extension 43 in which overflow tube 42 is integrally formed. The lid 14 of pressurizable liquid reservoir 10 incorporates central upwardly projecting walls 15 adapted to receive and retain closure cap 16. Closure cap 16 contains a threaded aperture 17 adapted to receive a threaded shaft 18 having a spring 19 depending therefrom and a knob 20 projecting above the threaded shaft 18. As seen in Figure 1 a reciprocating valve shaft 21 has an upper valve head 23 and a lower valve head 24. Lower valve head 24 has an integral external tube 25 extending downwardly concentrically outside overflow tube 42 which extends outwardly from the bottom of pressurizable liquid reservoir 10. The lower valve head 24 of valve shaft 21 engages the top of overflow tube 42 in closed position. The upwardly projecting walls 15 of the lid 14 include a portion of increased thickness at the bottom inside portion of the projecting walls 15 forming a valve seat 26 to receive the upper valve head 23 of valve shaft 21. Valve seat 26 is comprised of an upper inclined portion 27 and a lower vertical portion 28 in which valve head 23 seats when the upper valve head 23 is seated.

In operation the fluid in pressurizable liquid reservoir 10 is heated by microwaves creating a gas phase in the upper portion of the pressurizable liquid reservoir 10. The gas pressure acts against the surface of the fluid forcing fluid upwardly between concentric tubes 42 and 25 against lower valve head 24. The steam in the top portion of pressurizable liquid reservoir 10 exerts pressure against upper valve head 23 pushing against spring 19 biasing upper valve head 23 downwardly. When the pressure pushing upper valve head 23 and lower valve head 24 upwardly overcomes the downward pressure on upper flange 23 being exerted by spring 19, the valve 21 will move upwardly unseating lower valve head 24 from valve seat 28 thus releasing liquid from pressurizable liquid reservoir 10 up tube 25 and down tube 42 into filter 12 until the downward pressure of spring 19 overcomes the upward pressure of the fluid acting against lower valve head 24 and upper valve head 23, at which time the fluid flow will be shut off momentarily and no fluid will flow through outlet tube 42 to filter 12. The downward pressure exerted by spring 19 on upper flange 23 is controlled by rotating the knob 20 in closure cap 16 downwardly or upwardly by turning knob 20 clockwise or counterclockwise.

The upper valve head 23 remains in contact with the vertical portion 28 of upper valve seat 26 for some distance before gas is freely released through upper valve seat 26. Thus upper movement of valve shaft 21 against the bias of spring 19 will first allow water through lower tube 42 and subsequent upward pressure will unseat valve head 23 from upper valve seat 26 releasing steam from the top of pressurizable liquid reservoir 10.

Turning the knob 20 downwardly increases the downward bias of spring 19. When knob 20 is turned down, valve shaft 21 does not frequently release gas through upper valve seat 26 and liquid flows regularly from tube 42 into filter 12 removing some infusible material and producing a light drink.

Turning the knob 20 downwardly only a slight amount puts only a small bias on the spring 19. With the spring

19 exerting only a slight downward bias on the top of upper valve head 23, vapor pressure in the pressurizable liquid reservoir 10 will be more frequently released through upper valve seat 26 causing a reciprocating motion of valve shaft 21 resulting in an intermittent release of fluid through tube 42 into filter 12 and resulting in a stronger drink.

Referring to Figure 2, the top 23 of the reciprocating valve and the arrangement at the top of reservoir 10 remains the same as shown in Figure 1. As shown in Figure 2, the valve shaft 21 extends substantially to the bottom of the pressurizable liquid reservoir 10. Mounted on the bottom of valve shaft 21 is a lower valve head 50 adapted to fit in and seal the bottom aperture 51 in reservoir 10. The exterior shape of lower valve head 50 is the same as the interior shape of bottom projection 52 of pressurizable liquid reservoir 10 such that when the valve shaft 21 is biased downwardly by the spring 19 the bottom aperture 51 in the pressurizable liquid reservoir 10 is closed.

In operation, the valve shaft 21 operates in the same manner as described with respect to Figure 1, although no upward pressure is exerted against lower valve head 50 by fluid in Figure 2. On the contrary when lower valve head 50 is seated in bottom projection 52 in closed position, the vapor pressure acting against lower valve head 50 tends to keep the valve closed. The knob

20 is utilized in the same fashion as described in respect to the operation of Figure 1. When the knob 20 is moved clockwise to point to light (Figure 3) , increasing the bias of spring 19, a lighter drink will be obtained. When the knob 20 is moved counterclockwise to point to dark, Figure 3, decreasing the bias of spring 19, a darker drink will be obtained.

Claims

I CLAIM

1. A method of making a beverage from an infusible material in a microwave oven, employing an apparatus having a microwave transparent pressurizable liquid reservoir, said pressurizable liquid reservoir having a valve to release fluid, means to control the rate of release of gas and fluid from the pressurizable liquid reservoir, said pressurizable liquid reservoir being mounted in fluid communication with a filter chamber, said filter chamber mountable above a beverage receptacle, the method comprising: placing a supply of an infusible material in the filter chamber, mounting said filter chamber on a receptacle, pouring a liquid into the pressurizable liquid reservoir to a level below the top of the pressurizable liquid reservoir, securing the lid to the pressurizable liquid reservoir, mounting the pressurizable liquid reservoir in fluid communication with the filter chamber, adjusting the control means to control the rate of release of fluid from the pressurizable liquid reservoir, heating said liquid in said pressurizable liquid reservoir with microwave energy to raise the liquid vapor pressure in the pressurizable liquid reservoir sufficiently to move said valve sufficiently to open the lower valve and force said liquid from the pressurizable liquid reservoir through the lower valve into the filter chamber to make a beverage, and collecting the beverage in said receptacle.

2. The method of claim 1 wherein the control means is adjusted to provide both gas and fluid release from the pressurizable liquid reservoir causing an intermittent release of liquid through the lower valve.

3. The method of claim 2 in which the control means is comprised of a valve shaft which is normally biased downwardly towards the base of the pressurizable liquid reservoir.

4. The method of claim 3 in which the downward pressure exerted on the valve shaft may be adjusted to increase or decrease the pressure to control the strength of_the drink.

5. The method of claim 4 in which the downward pressure exerted on the top of the valve shaft is exerted by an adjustable spring exerting downward pressure on said valve shaft and adjustment of the pressure is effected by screwing or unscrewing a knob contacting the top of said adjustable spring.

6. A beverage brewing apparatus for use in a microwave oven, adapted to be placed over a beverage receptacle, comprising: a microwave transparent filter chamber having a filter positioned in a bottom part thereof, the filter adapted for holding a quantity of an infusible material and for dispensing of a brewed beverage therefrom into the receptacle, and a pressurizable microwave transparent reservoir adapted to hold a quantity of a liquid, said pressurizable microwave transparent reservoir being in fluid communication with said filter chamber, said pressurizable microwave transparent reservoir having a valve to release gas from the top of the pressurizable microwave transparent reservoir and water into the filter chamber, fluid control means in said pressurizable microwave transparent reservoir to control the rate of fluid flow from the pressurizable microwave transparent reservoir.

7. The apparatus of claim 6 wherein means are provided to control gas and fluid release from the pressurizable liquid reservoir causing an intermittent release of liquid through the lower valve.

8. The apparatus of claim 7 in which the control means is comprised of a valve shaft which is normally biased downwardly towards the base of the pressurizable liquid reservoir.

9. The apparatus of claim 8 in which the downward pressure exerted on the valve shaft may be adjusted to increase or decrease the pressure to control the strength of the drink.

10. The apparatus of claim 9 in which the downward pressure exerted on the top of the valve shaft is exerted by a spring exerting downward pressure on said valve shaft and adjustment of the pressure is effected by screwing or unscrewing a knob contacting the top of said spring.