JPH0521567B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a rice cooker, and more specifically, to open and close a pressure control valve that releases steam generated from inside the pot during rice cooking in accordance with the steam temperature. This invention relates to a rice cooker that can be controlled.

<Prior art and problems to be solved by the invention> In recent years, rice cookers have been widely used, focusing on the convenience of being able to cook rice and keep it warm in one device.

In these rice cookers, the pressure regulating valve, which releases steam inside the pot to the outside and regulates the internal pressure of the pot, has a simple structure, so the pressure regulating valve is composed of a ball-shaped valve body. The pressure was adjusted by its own weight.

However, with this structure, when the internal pressure of the pot rises during the early stages of cooking rice until it reaches boiling point, the valve opens and steam is released, making it impossible to maintain the internal pressure of the pot at a high level. Of course, it is possible to increase the weight of the valve body by keeping the internal pressure of the pot at high pressure, but steam cannot be released sufficiently during boiling, and the pressure regulating valve itself is large compared to the overall size of the rice cooker. This is not desirable because it becomes too large.

Therefore, a configuration may be considered in which the valve body is held down by a spring. With this, the desired pressure can be applied at low temperatures, but a constant valve pressure is applied even at boiling, making it impossible for sufficient steam to escape. For this reason, it is said that this actually hinders the ideal cooking process of cooking delicious rice, which involves applying pressure to heat the rice while keeping as much steam as possible when the temperature is low, and releasing as much steam as possible when the temperature is high. There was a problem.

This invention was made in view of the above problems, and is a rice cooker that can cook delicious rice by applying as much pressure as possible when the temperature is low, and by opening the valve when the temperature is high, allowing steam to flow freely. The purpose is to provide the following.

<Means for Solving the Problems> A means for solving the problems according to the present invention is a rice cooking jar in which a pressure regulating valve unit is provided in a predetermined part of the lid unit to maintain internal pressure while releasing rice cooking steam to the outside. In the above, the pressure regulating valve unit includes a valve seat formed with an opening for circulating rice cooking steam, a valve body that opens and closes the opening of the valve seat, and a valve body cover that surrounds the outside of the valve body. An inner cylindrical part for guiding the valve body is erected around the periphery of the opening of the valve seat, and a steam flow path communicating from the opening of the valve seat is formed in the inner cylindrical part. There is a valve disc between the valve disc and the valve disc cover.
A bias spring is interposed between the valve body and the inner cylindrical portion to urge the opening of the valve seat in a direction that closes it, and is expanded and transformed by the heat of the rice cooking steam to cause the valve body to A shape memory alloy spring is interposed to move the opening of the valve seat in the direction of opening it against the urging force of the bias spring.

<Function> In the above problem solving means, when the temperature is relatively low and steam is not sufficiently released, the valve body closes the opening of the valve seat due to the biasing force of the bias spring, so that the internal pressure of the pot decreases. can be maintained at a relatively high level.

Then, when the temperature reaches a high temperature where a lot of steam is produced,
The shape memory alloy spring undergoes elongation and transformation in response to the heat of the rice cooking steam. Along with this, the valve body is guided to the inner cylindrical part of the valve seat against the urging force of the bias spring, and smoothly moves along this inner cylindrical part in the direction of opening the opening of the valve seat. Therefore, the valve body can be reliably switched between the closed position and the open position with respect to the opening of the valve seat.

Furthermore, since a steam flow path leading from the opening of the valve seat is formed in the inner cylindrical portion that guides the valve body, this inner cylindrical portion can be used as a guide path for steam distribution, allowing the steam to flow. At the same time, a shape memory alloy spring is interposed between the valve body and the inner cylinder, so that the steam guided by the inner cylinder is transferred to the shape memory alloy spring. By bringing them into contact with each other, the elongated state of the memorized shape due to the heat of the rice cooking steam can be effected more reliably.

At the same time, this shape memory alloy spring can be interposed between the valve body and the inner cylinder part that guides the vertical movement of the valve body and the flow of steam.
This inner cylindrical portion can also be used as an intervening member for a shape memory alloy spring.

<Example> Next, an example of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway side sectional view of the rice cooking jar of the present invention, in which the inner pot 3 is removably stored in the outer case 2 with a heat insulating material interposed therein, and connected to the outer case 2 so that it can be opened and closed. Lid unit 4
A pot lid 5 is removably attached to the bottom surface of the pot. In addition, a heat-retaining heater 6 is installed facing the outer periphery of the inner pot 3, and a rice cooking heater 7 is installed so as to be in contact with the bottom surface of the inner pot 3.
is installed. A pressure regulating valve unit 1 of the rice cooker is detachably provided at a predetermined portion of a lid unit 4.

FIG. 2 is an enlarged sectional view of the pressure regulating valve unit 1. The pressure regulating valve unit 1 consists of an assembly of a valve body 23 including a rod-shaped valve 15, its valve seat 12, and a valve body cover 21 of the valve body 23, and is a so-called open-hole regulating valve that can maintain pressure while constantly releasing steam. It is a valve type.

The valve seat 12 has an opening 13 forming a steam vent formed in its center, and an inner cylindrical part 10 surrounding the outside of the rod-shaped valve 11 and guiding the valve body 23 at the periphery of the opening 13. has been erected. The inner diameter of the inner cylinder portion 10 is slightly larger than the opening diameter of the opening portion 13. Further, the bottomed cylindrical rod valve 11 with a circular cross section and a slightly smaller diameter than the opening diameter of the opening 13 has its lower end bottomed part movable in the vertical direction with respect to the opening 13 and the inner cylindrical part 10. It is coming. On the outside of the rod-shaped valve 11, a valve body 23 is integrally provided, which forms a cylindrical valve body with an upper end 15 folded back into a skirt shape, and has an air space with respect to the inner cylinder part 10. The valve body 23 is fitted so as to be vertically movable along the outer wall of the inner cylindrical portion 10 erected around the periphery of the opening 13 . Further, on the inner wall of the inner cylinder part 10, a plurality of guide pieces are formed from the opening edge of the opening 13 in order to form a long groove forming a steam flow path communicating with the opening 13 for guiding and releasing steam to the outside. 17 is provided upright, and this guide piece 17 is intended to guide the rod-shaped piece 11 up and down. The lower end portion 20 of the valve body 23 is slightly folded outward into a flange-like shape, and a coil-shaped bias spring 14 is interposed between this flange-like lower end folded portion 20 and the opening edge of the valve body cover 21. A coiled shape memory alloy spring 16 is interposed between the upper folded portion 15 of the valve body 23 and the upper end of the guide piece 17 provided on the inner wall of the inner cylinder portion 10 .

Further, a plurality of steam holes 22 are provided on the upper side surface of the valve body 23, and the steam from the inner pot 3 flows through the valve seat 1.
The steam rises from the opening 13 of No. 2 through the guide of a long groove forming a steam flow passage formed on the inner wall of the inner cylinder section 10, touches the shape memory alloy spring 16, and radiates to the outside through the steam hole 22.

Furthermore, a safety valve 8 is provided separately from the valve body 23, and this safety valve 8 is operated to release pressure when the valve body 11 malfunctions or when the pressure exceeds a predetermined pressure. be. The safety valve 8 includes a second opening 18 formed in the valve seat 12 apart from the opening 13, and a ball-shaped valve body 19 that closes the second opening 18 by its own weight. The weight of the valve body 19 is selected to be large in order to maintain the internal pressure of the inner pot at a high pressure during non-boiling.

The formation memory alloy spring 16 is made of, for example, Ni-Ti.
It is made of an alloy or a Cu-Al-Zn alloy, and is set to undergo martensitic transformation when the temperature reaches the temperature equivalent to the steam temperature flowing through the pressure regulating valve 1 during boiling (approximately 80°C to 95°C). , the shape is memorized in the stretched state. After the above transformation, the valve body 23 is expanded and pushed up, allowing steam to flow relatively easily through the steam hole 22 (see FIG. 3). The bias spring 14 always presses down and biases the valve body 23 in the closing direction relative to the opening 13. When the shape memory alloy spring 16 is at a low temperature, it pushes down the lower end 20 of the valve body 23 and biases it. When the shape memory alloy spring 16 is at a low temperature, it presses down and biases the lower end 20 of the valve body 23, so that the bottomed part of the rod-shaped valve 11 faces the opening 13, and a slight drop occurs.
Close it after a while. Therefore, steam can only pass through a small gap between the rod valve 11 and the opening 13.

Next, the operation of the rice cooker will be explained. First, a rice cooking switch (not shown) is turned on to energize the rice cooking heater 7 to start cooking rice. At the beginning of cooking,
The steam temperature is still low and the shape memory alloy spring 16 is not fully expanded. Therefore, valve body 2
3 is pushed down in the closing direction by the biasing force of the bias spring 14 (see Fig. 2), and the steam in the inner pot 3 is absorbed by a small amount of steam formed between the rod-shaped valve 11 and the inner wall of the inner cylindrical portion 10. 〓It only leaks through the gaps.
Therefore, the internal pressure of the inner pot 3 can be maintained at a relatively high pressure. However, as the rice cooking process progresses and the steam temperature rises, the shape memory alloy spring 16 transforms into a memorized shape, and the valve body 11 changes due to this transformation.
It is moved upward against the urging force of the bias spring 14, and the opening 13 is opened. (See Figure 3). Therefore, by opening the opening 13, steam can be freely blown out from the steam hole 22, and the inner pot 3
The internal pressure drops rapidly. Further, as the rod-shaped valve 11 moves upward, the valve body 23 protrudes from the upper surface of the lid unit 4, and steam is spewed out, so that the cook can know that the boiling process has begun.

When the rice is cooked and the heat retention process begins, the steam temperature drops, so the shape memory alloy spring 16 returns to its original memorized shape and the rod-shaped valve 11 closes the opening 13, making the steam in the inner pot 3 almost colder than the outside air. Cut off. Yotsute inner pot 3
It can prevent outside air from flowing inside and increase the heat retention effect.

Further, since the valve body 23 smoothly moves along the inner cylindrical portion 10 of the valve seat 12 due to the urging force of the bias spring 14 or the transformation of the shape memory alloy spring 16, the opening of the valve body 12 of the valve body 23 Switching between the closed position and the open position with respect to the portion 13 is ensured.

Furthermore, since a steam flow path leading to the opening 13 of the valve seat 12 is formed in the inner cylindrical portion 10 of the valve seat 12, the opening 13 of the valve seat 12 is closed and the internal pressure of the inner pot 3 is compared. Even when the temperature is maintained at a high level, steam rises from the opening 13 of the valve seat 12 through the steam flow path of the inner cylinder 10 and slightly exits from the steam hole 22, so the internal pressure of the pot is not excessive. can be prevented from rising.

FIGS. 4 and 5 are enlarged sectional views showing other embodiments. Pressure control valve unit 3 of this embodiment
The valve seat 42 of No. 1 has an opening 43 forming a steam vent formed in its center, and an inner cylindrical part 44 having an inner diameter slightly larger than the opening diameter of the opening 43 is formed around the periphery of the opening 43. has been erected. Inner cylinder part 44
A ball-shaped ball valve 41 that opens and closes the opening 43 is inserted inside. In addition, the inner cylinder part 44
A plurality of long grooves forming steam flow passages communicating with the opening 43 are formed in the inner wall of the tube. The diameter of the ball valve 41 is slightly smaller than the inner diameter of the inner cylinder part 44 and can move up and down freely inside the inner cylinder part 44.
It is wider than the aperture diameter of. The upper part of the inner cylindrical part 44 has an inner diameter slightly larger than the outer diameter of the inner cylindrical part 44 so as to be spaced a predetermined distance from the valve seat 42 even when the ball valve 41 closes the opening 43. A valve body 45 forming a cylindrical valve body having
is covered so that it can move up and down. A presser rod 47 that presses the ball valve 41 from above hangs down from the center of the upper surface (ceiling surface) of the valve body 45 .
A plurality of steam holes 46 are formed in predetermined portions of the ceiling surface and side surfaces (skirts) of. Steam in the inner pot 3 enters through the opening 43 , rises up through a long groove forming a steam flow path formed on the inner wall of the inner cylinder 44 , touches a shape memory alloy spring 50 (described later), and passes through the steam hole 46 . It dissipates into the room. moreover,
A valve body cover 48 having an inner diameter slightly larger than the outer diameter of the valve body 45 is provided upright around the opening 43 so as to be concentric with the inner cylindrical portion 44 . Valve body 45
The side wall of the valve body 45 is inserted between the inner cylindrical portion 44 and the valve body cover 48, and the lower end portion 49 of the valve body 45 is slightly folded back outward. Then, the ceiling surface of the valve body 45 and the inner cylinder part 44 of the valve seat 42
A spring 50 made of a shape memory alloy is interposed between a spring receiving recess formed in the outer peripheral wall of A bias spring 51 is interposed therebetween.

Furthermore, a negative pressure absorption valve 32 is provided separately from the pressure regulating valve unit 31. Negative pressure absorption valve 3
2 is for operating when the internal pressure of the inner pot 3 decreases below a reference value to take atmospheric air into the inner pot 3. The negative pressure absorption valve 32 includes a second opening 52 formed in the valve seat 42 separately from the opening 43, a valve body 53 that opens and closes the second opening 52, and one end of the valve body 53 attached to the base 42. It is composed of a pin 54 that is inserted and fixed. When the temperature of the inner pot 3 decreases during heat retention, etc., and the pressure of the inner pot 3 becomes negative, the valve body 53
is bent inward due to negative pressure, and the second opening 52
open. Then, since outside air is taken into the inner pot 3, the pressure in the inner pot 3 can be prevented from decreasing excessively.

The shape memory alloy spring 50 is made of, for example, Ni-Ti.
It is made of alloy or Cu-Al-Zn alloy, and its shape is memorized in the stretched state, so after it reaches high temperature and undergoes martensitic transformation, it pushes up the valve body 45 and the steam flows through the opening 43. , steam vent 46
(See Figure 5). The bias spring 51 always pushes down the valve body 45 and biases it in the closing direction, and when the shape memory alloy spring 50 is at low temperature, it overcomes the shape memory alloy spring 50 and pushes the flanged lower end 49 of the side wall of the valve body 45.
Press down. The presser rod 47 presses the ball valve 41 from above and closes the opening 43.

Next, the operation of the pressure regulating valve unit 31 will be explained. When the steam temperature is still low at the beginning of rice cooking, the shape memory alloy spring 50 is not fully expanded. Therefore, the ball valve 41 is pushed down by the bias spring 51 via the presser rod 47 of the valve body 45 (see Fig. 4), and the steam in the inner pot 3 cannot escape. in a state. In this way, the steam inside the inner pot 3 can be prevented from escaping, and the internal pressure can be relatively increased. However, when the internal pressure of the inner pot 3 rises above the reference value (often the internal pressure of the inner pot 3 rises instantaneously), the internal pressure overcomes the pressure of the bias spring 51 and pushes up the ball valve 41, so the steam passes between the ball valve 41 and the opening 43 and exits from the steam hole 46. Thereby, an excessive increase in the internal pressure of the inner pot 3 can be prevented.

When the boiling process is reached, the temperature of the steam that comes into contact with the shape memory alloy spring 50 becomes high, and the steam transforms into a memorized shape, causing the shape memory alloy spring 50 to elongate (see FIG. 5). As a result, the valve body 45 overcomes the urging force of the bias spring 51 and is pushed upward, and the pressing force applied to the ball valve 41 is released. Then, since the ball valve 41 only presses down the opening 43 by its own weight, the steam can escape from the steam hole 46 relatively freely. Therefore, the internal pressure of the inner pot 3 rapidly decreases. Further, the valve body 45 is connected to the pressure regulating valve unit 31.
Since the valve body cover 48 protrudes from the valve body cover 48 and steam is vigorously jetted out from the steam hole 46, the cook can know that the boiling process has begun. When the rice is finished cooking and begins the warming process, the steam vent 46
Since the temperature of the steam is lowered by the cold outside air flowing in, the valve body 31 returns to its original memorized shape as shown in FIG. 4, and the inside of the inner pot 3 is cut off from the outside. Therefore, it is possible to prevent outside air from flowing into the inner pot 3 and enhance the heat retention effect. In addition, if the heat retention is continued for a long time, the heat retention inside the inner pot 3 will decrease and the inside of the inner pot 3 will become in a negative pressure state, but at this time, the negative pressure absorption valve 32 will work and the pressure inside the inner pot 3 will be returned to normal. can. Therefore, inconveniences such as difficulty in opening the lid unit 4 due to negative pressure can be prevented. Note that other effects are the same as in the previous embodiment.

FIG. 6 shows a modification of the embodiment shown in FIGS. 4 and 5, in which the same members are given the same reference numerals. This modification is intended to more quickly lower the temperature of the shape memory alloy spring after rice cooking when the shape memory alloy spring is used for pressure regulation.
In this modification, the steam hole 46 is tilted diagonally upward, and a guide piece 46a facing diagonally upward is provided on the side inner wall of the valve body 45.
The outside air entering from 6 can be smoothly guided to the steam hole 46 provided on the ceiling surface of the valve body 45.

When rice cooking is finished and the warming process begins, a large amount of outside air enters along the guide piece 46a as shown by the arrow in FIG. 6, mixes with the high temperature steam coming out between the openings 43, and quickly lowers the temperature of the steam. lower to Therefore, the shape memory alloy spring 50 is quickly cooled, the valve body 45 can be returned to the valve open state more quickly, and the heat retention effect can be enhanced.

Note that the steam hole 46 is not provided with the guide piece 46a.
Simply tilting the shape memory alloy spring 50 diagonally upward can promote the introduction of outside air and provide the effect of cooling the shape memory alloy spring 50 more quickly.

<Effects of the Invention> As described above, according to the present invention, the valve body and the opening of the valve seat are opened using the deforming force of the shape memory alloy spring that is elongated and transformed into a memorized shape by the heat of rice cooking steam. When the temperature of the rice cooking steam is low, the valve element is moved in the direction of closing the opening of the valve seat by the urging force of the bias spring, and the valve is closed. The opening of the seat can be closed, so when a lot of steam is coming out, it can be released sufficiently, and when it is relatively low and not enough steam is coming out, it can be used to compare the internal pressure of the pot. can be maintained at a high level.

Therefore, the internal pressure is increased at the beginning of cooking rice at low temperature,
Not only can you quickly bring the rice to a boil, but when it boils at high temperatures, you can open the valve body to release steam and cook delicious rice.

In particular, the valve body is guided to the inner cylindrical part of the valve seat by the biasing force of the bias spring or the transformation of the shape memory alloy spring, and moves smoothly along this inner cylindrical part. It is possible to reliably switch between a closed position and an open position with respect to the opening.

Furthermore, the inner cylindrical part that guides the valve body is formed with a steam flow path that leads from the opening of the valve seat, so this inner cylindrical part can be used as a guide part for the flow of steam, and the steam can flow through the inner cylinder part. At the same time, a shape memory alloy spring is interposed between the valve body and the inner cylindrical passage, so that the steam guided by the inner cylindrical part is transferred to the shape memory alloy spring. By bringing them into contact with each other, the elongation transformation of the memory shape due to the heat of the rice cooking steam can be effected more reliably.

At the same time, this shape memory alloy spring can be interposed between the valve body and the inner cylinder part that guides the vertical movement of the valve body and the flow of steam.
This inner cylindrical portion can also be used as an intervening member for a shape memory alloy spring.

Furthermore, since the valve body is provided with its upper end facing outside from the top surface of the lid unit, during the boiling process, the valve body protrudes from the top surface of the lid unit and steam is spouted out. This has the unique effect of making it easy to confirm from the outside that this has been achieved.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway sectional view of a rice cooker equipped with a pressure regulating valve, Fig. 2 is an enlarged sectional view of the pressure regulating valve, and Fig. 3 is an enlarged sectional view of the pressure regulating valve showing the valve in an open state. FIG. 4 is a sectional view showing another embodiment of the pressure regulating valve, FIG. 5 is a sectional view of the pressure regulating valve showing the valve in an open state, and FIG.
FIG. 7 is a cross-sectional view showing a modification example of the figure. 1, 31, 61...Pressure control valve unit, 1
4,51,65...bias spring, 16,50,
68...Shape memory alloy spring.

Claims (1)

[Scope of Claims] 1. A rice cooking jar in which a pressure regulating valve unit for maintaining internal pressure while releasing rice cooking steam to the outside is provided in a predetermined part of the lid unit, wherein the pressure regulating valve unit is used for cooking rice. The valve seat includes a valve seat formed with an opening for flowing steam, a valve body that opens and closes the opening of the valve seat, and a valve body cover that surrounds the outside of the valve body, the opening of the valve seat. An inner cylindrical part for guiding the valve body is erected around the periphery of the valve body, and a steam flow passage leading from the opening of the valve seat is formed in the inner cylindrical part, and the valve body and the valve are connected to each other. Between the body cover and the valve body,
A bias spring is interposed between the valve body and the inner cylindrical portion to urge the opening of the valve seat in a direction that closes it, and is expanded and transformed by the heat of the rice cooking steam to cause the valve body to A rice cooking jar characterized in that a shape memory alloy spring is interposed to move the opening of the valve seat in the direction of opening it against the biasing force of the bias spring.