GB2102698A - Pressure cooker - Google Patents

Abstract

A timing device for pressure cooker comprises a pressure actuated member (1) being partly inserted inside the cooker body (10); a time-switch (6) connected in series with a heating coil (51) provided in the jacketed wall of the cooker body; and a controlling means provided between said pressure actuated member (1) and said time- switch (6); whereby the controlling means control the time switch to start timing when it is pushed by the pressure actuated member. <IMAGE>

Description

SPECIFICATION A timing device for pressure cooker This invention relates to an electric pressure cooker, particularly to a timing device therefor capable of timing from an instant when a predetermined pressure is reached in the cooker.

Commonly, a non-electric pressure cooker has no timing device and therefore the cooking time is determined by the user after the pressure regulating valve of the cooker operates. In an electric pressure cooker a timing device is provided in the heating system in which the timing is started as soon as electricity is supplied. As the cooking time usually given in a direction table for a pressure cooker is based on the timing started when a certain pressure is reached in the cooker there is a difference in timing between two conditions.

Further, even though it is possible to add a boiling time to the given cooking time to determine the entire cooking time of the pressure cooker, the above timing device is still considered unsatisfactory due to difficult estimation of boiling time caused by some factors like food quantities, temperature, etc. in the cooker.

In this invention the timing device for a pressure cooker comprises a pressure actuated member and controlling means to control a time switch to start timing when the pressure in the cooker attains a predetermined state.

An object of the invention is to provide a novel timing device in which the time switch will start timing when the pressure in the cooker reaches a predetermined state.

The invention will now be described further by way of example with reference to the accompanying drawings in which: Figure 1 is a sectional view of a first embodiment of a pressure cooker illustrating the condition in which the circular disc is gripped by the gripping member; Figure 2 is a sectional view of the first embodiment illustrating that the gripping member is disengaged from the circular disc to let the time-switch work; Figure 3 is a sectional view of the second embodiment of the invention; Figure 4 is a schematic top view of the cover of the second embodiment; Figure 5 is circuit diagram showing a temperature controlling means connected in series with the time-switch and heating coil.

Figure 6 is a schematic sectional view of the third preferred embodiment of the invention; and Figure 7 is a circuit diagram for the combined heating and timing system of the third preferred embodiment.

As shown in Fig. 1 the first preferred embodiment of a timing device is provided in a housing 5 attached to the side wall of a pressure cooker 1 0. The timing device includes a horizontal pressure actuated pushing member 1 being partly inserted movably inside the cooker body 10 and the sliding contact thereof is sealed by a rubber washer 11. A screen 7 is provided to avoid clogging thereabout. A vertical gripping member 2 is supported pivotally at its middle portion 21 and have its upper end placed between the outer end of the pushing member 1 and a controlling spring member 3 in contact position. A time-switch 6, having a button 62, is connected in series with the heating coil 51 in the circuit of the heating system and on the shaft 61 -thereof a circular disc 4 which has an annularly corrugated surface 41 is fixedly sleeved.As the time-switch 6 is not the feature of this invention it will not be discussed hereinafter.

Figure 1 shows the condition of the gripping member 2 when the pressure in the cooker 10 is lower than the predetermined pressure. When the gripping member 2 is in its normal position in which it is thrusted by the spring member 3 it grips the disc 4 through the depression of the corrugated surface 41 to prevent the shaft 61 from turning as well as the time-switch from working athough the electricity flows thereinto. When the pressure increasses to a predetermined state it will actuate the pushing member as shown in Fig. 2 to force the gripping member 2 against the spring member 3 so that it will disengage from the disc to enable the timeswitch to start timing. As the disc 4 is gripped in springy position the rotation of the shaft 61 can be reversed if the set time is beyond the requirement.

To avoid superheating in the cooker in case of the timing being wrongly set up in excess of requirement a heat sensitive switch can be further provided in the circuit of the heating system for safety purposes.

In the second embodiment, the timing device is provided in a housing 1 2 disposed on the cover 8 of the cooker as shown in Figs. 3 and 4. The cover 8 and handle 81 are of integral construction and hingedly attached to the cooker 10 by means of a fixing member 83 and a pivot 82. A fastener 84 is provided for fastening the cover 8 with the cooker vessel. The conducting wire from the time switch 6 is connected to the electric source by passing through the inside part of the handle 81 and along the side wall of the cooker body 10.

In common practice, after the pressure in a pressure cooker reaches a certain state the heat source can be reduced to about 70% of the original heat energy. It does not change the cooking effect and in addition saves the heat energy consumed. Therefore it is advisa ble to provide a temperature control circuit 9 in connection with the time-switch 6 and heating coil 51 in both the first and second embodiments to control the temperature of the heating coil 51 as shown in Fig. 5. As the temperature control circuit 9 is not within the scope of the invention it will not be explained hereinafter.

In the circuit of Fig. 5, a micro-switch 91 is used to control the conduction of the TRIAC 92 so as to vary the current flowing in the heating coil 51. Regarding the location of the micro-switch 91, it is illustrated in Figs. 1 and 2. In Fig. 1 the gripping member 2 is in non pushing position relative to the switch 91. At this time, the bias required for the TRIAC 92 to provide large conductivity is supplied through the normally closed contact of the switch 91 enabling the heating coil 51 to reach maximum heat. When the gripping member 2 is at the position as shown in Fig.

2, it will push the switch 91 to provide another bias through its normally open contact to the TRIAC 92 for effecting the smaller conductivity, thus reducing the current and causing 30% reduction in heat in the heating coil 51.

As shown in Fig. 6 the third preferred embodiment of the timing device includes a pushing member identical with that of the first and second embodiments. At the pushing end thereof a micro switch 92 is provided. By means of said micro switch 93 either an electronic type or a motor speed reducing type time-switch can be directly controlled.

The circuit connection is shown in Fig. 7 wherein the terminals A and B are current entering point of the time switch and C, D are the controlling terminals of the time-switch 6.

With the invention thus explained, it is obvious that modification and variations thereof can be made without departing from the scope of the invention as defined by the appended claims.

Claims (8)

1. A timing device for a pressure cooker comprising, a pressure actuated member, partly inserted inside the pressure cooker body and capable of moving outwardly when subjected to a predetermined vapour pressure in the cooker body; a time-switch connected in series with a heating coil provide in a jacketed wall of the cooker body; a controlling means provided between said pressure actuated member and said time switch, whereby the controlling means control the time switch to start timing when it is pushed by the pressure actuated member.

2. A timing device as claimed in Claim 1, wherein said controlling means comprises, a gripping member, supported pivotally at its middle portion, having a first end for being subjected to the force from the outer end of said pressure actuated member; a controlling spring member being provided at said gripping member for restoring said gripping member to its original position when the pressure decreases; whereby when the pressure actuated member moves outwardly it will push the first end of the gripping member to make a second end thereof disengage from a turnable shaft of the time-switch to let it start timing.

3. A timing device as claimed in Claim 2, wherein said controlling means further comprises a circular member, sleeved fixedly to the turnable shaft of the time-switch, having an annularly corrugated surface to enable the gripping member to grip thereat so that the time-switch is prevented from working.

4. A timing device as claimed in Claim 1, wherein said controlling means is a microswitch to control on-off action of the timeswitch.

5. A timing device as claimed in Claim 3 or 4 is provided on the cover of the cooker body.

6. A timing device as claimed in Claim 3 or 4 is provided at the side wall of the cooker body.

7. A timing device as claimed in Claim 3 further comprising temperature controlling means in series connection with the timeswitch and heating coil.

8. A timing device for a pressure cooker substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.