JP6213833B2 - Pressure cooker - Google Patents

Description

  The present invention relates to a pressure rice cooker that cooks rice in a pan in a pressurized state.

  Conventionally, as this type of pressure rice cooker, for example, a rice cooker disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-344568) is known.

  A conventional pressure rice cooker includes a pressure valve that opens and closes a steam discharge hole provided in a lid, and a pressure valve opening and closing mechanism that adjusts the pressure in the pan by switching the opening and closing state of the steam discharge hole by the pressure valve. And a control unit that controls the pressure valve opening and closing mechanism to perform the rice cooking process. FIG. 10: is a graph which shows the change of the temperature and pressure in a pan in the rice cooking process of the conventional pressure type rice cooker.

  As shown in FIG. 10, the control unit controls the pressure valve opening / closing mechanism so that the pressure in the pan drops from near 1.2 atmospheres to near atmospheric pressure (1.0 atmospheres) in the first half of the boiling maintenance step. Control to perform multiple times. Thereby, multiple bumping phenomenon generate | occur | produces in a pan, and the to-be-cooked rice in a pan is stirred. As a result, heat is efficiently transmitted to the cooked rice, and rice with good taste can be cooked.

JP 2004-344568 A

  However, in the conventional pressure rice cooker, the surface of the cooked rice may become sticky (has viscosity), and there is still room for improvement in terms of improving the taste.

  Accordingly, an object of the present invention is to provide a pressure rice cooker that can improve the above-described conventional problems and can further improve the taste of rice by suppressing the stickiness of the surface of the rice.

In order to achieve the object, the pressure rice cooker according to the present invention is:
A pot for storing cooked rice containing water and rice;
A heating device for heating the pan;
A lid that closes the opening of the pan;
A pressure valve that opens and closes a steam discharge hole communicating the inside of the pan and the lid;
A pressure valve opening and closing mechanism that adjusts the pressure in the pan by switching the opening and closing state of the steam discharge hole by the pressure valve;
A controller that controls the heating device and the pressure valve opening / closing mechanism to perform a rice cooking process including a water absorption process, a temperature rising process, and a boiling maintaining process;
A pressure rice cooker comprising:
The control unit controls the pressure valve opening / closing mechanism to switch the steam discharge hole from a closed state to an open state at least once in each of the first half and the second half of the boiling maintenance step, and the steam discharge hole The pressure valve opening / closing mechanism is controlled so that the time during which the steam discharge hole immediately before switching to the open state is closed is longer in the second half of the boiling maintenance step than in the first half of the boiling maintenance step. Has been.

  According to the pressure-type rice cooker which concerns on this invention, the stickiness of the surface of rice can be suppressed and the taste of rice can be improved further.

It is a front view of the pressure type rice cooker which concerns on 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the pressure type rice cooker of FIG. It is an expanded sectional view which shows the pressure valve with which the pressure type rice cooker of FIG. 1 is equipped, and a pressure valve opening / closing mechanism. It is a block diagram which shows the structure of the control part with which the pressure type rice cooker of FIG. 1 is provided. It is a graph which shows the change of the temperature in a pan, and the pressure in the rice cooking process of the white rice and normal rice cooking course of the pressure type rice cooker of FIG. It is a flowchart which shows the control action of the control part in the water absorption process and temperature rising process of a white rice and normal rice cooking course. It is a graph which shows the change of the temperature in a pan, and the pressure in the rice cooking process of the pressure type rice cooker which concerns on 2nd Embodiment of this invention. It is a graph which shows the change of the temperature in a pan, and the pressure in the rice cooking process of the pressure type rice cooker which concerns on 3rd Embodiment of this invention. It is a graph which shows the change of the temperature in a pan, and the pressure in the rice cooking process of the pressure type rice cooker which concerns on 4th Embodiment of this invention. It is a graph which shows the change of the temperature and pressure in a pan in the rice cooking process of the conventional pressure type rice cooker.

(Knowledge that became the basis of the present invention)
As a result of intensive studies on the cause of the sticky surface of rice and the deterioration of the taste of rice in the conventional pressure rice cooker, the present inventors have obtained the following knowledge.

  In the conventional pressure rice cooker, in the first half of the boiling maintenance step, the pressure in the pan is reduced from around 1.2 atm to near atmospheric at a stretch. In the first half of the boiling maintenance process, all the water is not absorbed by the rice, and a lot of water remains in the pan, so a bumping phenomenon occurs in the pan, and the cooked rice in the pan is stirred. The At this time, a stirring force is generated in the pan due to a pressure fluctuation of about 0.2 atm.

  The present inventors have found that since the stirring force generated at this time is too strong, the rice grains rub against each other and the structure of the surface of the rice grains collapses, resulting in stickiness on the surface of the cooked rice. Further, the inventors reduced the pressure in the pan at a stretch in the latter half of the boiling maintenance step, so that boiling bubbles are generated vigorously from the bottom of the pan, and the boiling bubbles pass between the rice grains to heat each rice grain. It was found that rice can be cooked with excellent taste and quality as a result of raising rice grains while communicating efficiently. Furthermore, the present inventors reduced the pressure in the pan at a stretch in the second half of the boiling maintenance step, but the water in the pan was greatly reduced in the second half of the boiling maintenance step. It was found that the product was hardly stirred and the rubbing between the rice grains was suppressed. As a result of intensive studies based on these novel findings, the present inventors have reached the following invention.

According to the first aspect of the present invention, a pot for containing cooked rice containing water and rice;
A heating device for heating the pan;
A lid that closes the opening of the pan;
A pressure valve that opens and closes a steam discharge hole that communicates the inside of the pan and the lid;
A pressure valve opening and closing mechanism that adjusts the pressure in the pan by switching the opening and closing state of the steam discharge hole by the pressure valve;
A controller that controls the heating device and the pressure valve opening / closing mechanism to perform a rice cooking process including a water absorption process, a temperature rising process, and a boiling maintaining process;
A pressure rice cooker comprising:
The control unit controls the pressure valve opening / closing mechanism to switch the steam discharge hole from a closed state to an open state at least once in each of the first half and the second half of the boiling maintenance step, and the steam discharge hole A pressure type that controls the pressure valve opening / closing mechanism so that the time during which the steam discharge hole immediately before switching to the open state is closed is longer in the second half of the boiling maintenance step than in the first half of the boiling maintenance step. Provide rice cooker.

  According to the second aspect of the present invention, the control unit is configured to maintain the boiling more than the first half of the boiling maintaining step in which the amount of pressure decrease in the pan caused by switching the steam discharge hole from the closed state to the opened state. The pressure-type rice cooker according to the first aspect, wherein the pressure valve opening / closing mechanism is controlled so that the latter half of the process becomes larger.

  According to a third aspect of the present invention, the control unit controls the pressure valve opening / closing mechanism so that the amount of decrease in the pressure in the pan in the first half of the boiling maintenance step is 0.05 atm or more. Item 3. A pressure rice cooker according to item 2.

  According to the 4th aspect of this invention, the said control part is the difference of the fall amount of the pressure in the said pan in the latter half of the said boiling maintenance process, and the fall amount of the pressure in the said pan in the first half of the said boiling maintenance process. The pressure-type rice cooker as described in the 2nd or 3rd aspect which controls the said pressure valve opening / closing mechanism so that it may become 0.02 atmospheres or more is provided.

  According to a fifth aspect of the present invention, the controller controls the pressure valve opening / closing mechanism to reduce the pressure in the pan at a stretch so that a bumping phenomenon occurs in the pan in the first half of the boiling maintenance step. And controlling the pressure valve opening and closing mechanism so that the pressure in the pan is reduced at a stretch so that boiling bubbles passing through the rice grains are generated in the pan in the latter half of the boiling maintenance step. The pressure type rice cooker as described in any one of the aspects is provided.

  According to the sixth aspect of the present invention, the first half of the boiling maintenance step is the first half when the period required for the boiling maintenance step is equally divided into two, and the second half of the boiling maintenance step is the boiling maintenance. The pressure rice cooker as described in any one of the 1st-5th aspect which is a period of the second half when the period which a process requires is equally divided into 2 is provided.

  According to the seventh aspect of the present invention, the first half of the boiling maintenance step is the first half when the period required for the boiling maintenance step is equally divided into three, and the second half of the boiling maintenance step is the boiling maintenance. The pressure rice cooker as described in any one of the 1st-5th aspect which is a period of the second half when the period which a process requires is equally divided into 3 is provided.

  According to an eighth aspect of the present invention, the control unit opens the steam discharge hole during the temperature raising step, and closes the steam discharge hole at the start of the boiling maintenance step. The pressure type rice cooker as described in any one of the 1st-7th aspect which controls a pressure valve opening / closing mechanism is provided.

According to the ninth aspect of the present invention, further comprising a pressure sensor for detecting the pressure in the pan,
The said control part provides the pressure type rice cooker as described in any one of the 1st-8th aspect which controls the said pressure valve opening / closing mechanism based on the detection pressure of the said pressure sensor.

According to the tenth aspect of the present invention, it further comprises an operation unit capable of selecting one rice cooking menu from a plurality of rice cooking menus including the standard rice cooking menu,
When the time of the water absorption process corresponding to the rice cooking menu selected by the operation unit is longer than the time of the water absorption process corresponding to the standard rice cooking menu, the control unit performs the pressure during the boiling maintenance process. The pressure rice cooker according to any one of the first to ninth aspects, wherein the number of times of switching the steam discharge hole from the closed state to the open state by controlling the valve opening / closing mechanism is greater than that of the standard rice cooking menu. To do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, embodiment shown below illustrates the pressure type rice cooker for materializing the technical idea of this invention, Comprising: This invention is not intended to specify this pressure type rice cooker. Other embodiments within the scope of the claims are equally applicable.

(First embodiment)
A pressure rice cooker according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a front view of a pressure rice cooker according to the first embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the pressure rice cooker of FIG. The pressure-type rice cooker 1 which concerns on this 1st Embodiment is a pressure-type rice cooker which raises the pressure in a pan to atmospheric pressure or more (for example, about 1.2 atmospheres) at the time of rice cooking.

  As shown in FIG. 2, the pressure rice cooker 1 includes a pot 10 that contains a cooked rice containing water and rice, a substantially bottomed cylindrical rice cooker body 2 that contains the pot 10, and a pot 10. And a lid 11 attached to the upper portion of the rice cooker body 2 so as to close the opening.

  As shown in FIG. 2, the pan 10 has a flange portion 10b around the upper opening 10a. The pot 10 is formed in a size that can be cooked with about 3 cups of rice, for example. Moreover, the pan 10 is provided with the inner layer formed with a material (for example, copper, aluminum, etc.) with high heat conductivity, and the outer layer formed with a magnetic material (for example, stainless steel). The surface of the inner layer of the pan 10 is covered with, for example, a fluororesin.

  The rice cooker body 2 includes a substantially bottomed cylindrical outer case 3 and a substantially bottomed cylindrical inner case 4 accommodated in the outer case 3. The inner case 4 is composed of a heat-resistant resin molded body. A substantially circular opening 41 into which the pan 10 can be inserted is formed in the upper part of the inner case 4. The inner case 4 is formed so as to detachably accommodate the pan 10 through the opening 41. The outer case 3 is configured by a decorative box having an outer shape larger than that of the inner case 4. An opening 31 is provided in the upper part of the outer case 3. The opening 31 of the outer case 3 is larger than the opening 41 of the inner case 4 and is formed in a substantially elliptical shape.

  The inner case 4 includes a substantially bowl-shaped bottom part 4a having a predetermined diameter, and a cylindrical side wall part 4b erected from the periphery of the bottom part 4a. A pan bottom heater H1 is attached to the bottom 4a. The pan bottom heater H1 is fixed to the bottom portion 4a using, for example, a support (not shown). The pot bottom heater H1 is, for example, a heater with a power consumption of 1200 watts, and is configured by an electromagnetic induction coil that induction-heats the bottom of the pot 10. The pot bottom heater H1 generates eddy current at the bottom of the pot 10 to cause the pot 10 itself to self-heat. Further, a bottom sensor (pan temperature detecting unit) Sen <b> 1 that detects the temperature of the bottom of the pot 10 is provided on the bottom 4 a of the inner case 4. The bottom sensor Sen1 also functions as a rice cooking amount detection unit that detects the amount of rice cooking in the pan 10. In addition, since it is already well-known to detect the amount of rice cooking in the pan 10 by the output of the bottom sensor Sen1, detailed description is omitted. As the bottom sensor Sen1, for example, a thermistor can be used.

  A mounting portion 42 is formed on the inner peripheral surface of the side wall portion 4 b of the inner case 4. The attachment portion 42 is located between the opening portion 41 and the bottom portion 4a, and is formed to be recessed by a predetermined depth from the inner peripheral surface side toward the outer peripheral surface side. A side heater H <b> 2 is attached to the attachment portion 42. The side heater H2 is composed of, for example, an electromagnetic induction coil that induction-heats the side surface of the pan 10.

  As shown in FIG. 2, a frame cover 6 is attached to the upper end portion of the outer case 3 and the upper end portion of the inner case 4. The frame cover 6 is configured by an annular plate body whose outer shape is substantially elliptical so as to cover an opening between the upper end portion of the outer case 3 and the upper end portion of the inner case 4. The frame cover 6 is made of resin, for example. A frame cover reinforcing member 7 is attached to the frame cover 6.

  The periphery of the opening of the frame cover 6 functions as a placement portion on which the flange portion 10b of the pan 10 is placed. At the periphery of the opening of the frame cover 6 located on the front side (left side in FIG. 2) of the rice cooker body 2, a locking member 8 for locking one end of the lock mechanism 16 provided on the lid 11 is provided. ing. The locking member 8 includes a locking piece 8b that locks with a locking claw 17a provided at one end of the locking mechanism 16, and a base 8a that is positioned above the locking piece 8b and fixes the locking piece 8b. And. The flange portion 10b of the pan 10 is placed on the upper surface of the base 8a. The base 8a is made of, for example, a heat resistant resin member. The locking piece 8b is made of, for example, a metal plate. The base 8a, the locking piece 8b, the frame cover 6 and the frame cover reinforcing member 7 are laminated and screwed together.

  Further, on the periphery of the opening of the frame cover 6 located on the rear side (right side in FIG. 2) of the rice cooker body 2, a base 8 a ′ on which the flange portion 10 b of the pan 10 is placed and the rear end of the lid 11 And a hinge portion 9 that pivotally supports the portion. The upper surface of the base 8a 'is formed so as to be located on the same horizontal plane as the upper surface of the base 8a. The hinge portion 9 includes a first attachment portion 9a that is fixed to the frame cover 6, and a second attachment portion 9b that pivotally supports the rear end portion of the lid 11 so as to be pivotable. The hinge part 9 is comprised by the substantially L-shaped plate-shaped member in the side view. The hinge portion 9 is configured to have such a strength that it does not deform even when a load is applied due to the weight of the lid body 11 or a pressure increase in the pan 10. For example, the hinge part 9 is comprised by the die-cast molded object which consists of metal members, such as stainless steel, aluminum, and aluminum alloy which have a thickness of about 2-5 mm. The pedestal 8a ', the frame cover 6, the hinge member 9, and the first attachment portion 9a are laminated and screwed together.

  A predetermined gap is formed between the outer case 3 and the inner case 4. A control unit 30 shown in FIG. 4, a cooling fan (not shown) that forcibly cools the inside of the rice cooker body 2, and a motor (not shown) that drives the cooling fan are arranged in the gap. Yes.

  As shown in FIG. 1, a display operation unit 5 is provided on the front surface of the outer case 3. The display operation unit 5 includes an operation panel (operation unit) 5a and a display panel 5b. The operation panel 5a is provided with various operation keys such as a start key, a menu key, a reservation key, and a heat retention key. The display panel 5b displays information such as a rice cooking course (for example, white rice / normal rice cooking course, brown rice cooking course) set by using various operation keys of the operation panel 5a.

  As shown in FIG. 2, the lid 11 is configured to rotate around a hinge pin 91 of the hinge portion 9. The lid 11 includes an inner lid 12 that closes the upper opening 10 a of the pan 10 and an outer lid 15 that is located above the inner lid 12 and closes the upper opening of the rice cooker body 2.

  As shown in FIG. 2, a safety valve V <b> 1 and a pressure valve 13 are provided on the upper surface of the inner lid 12. The safety valve V1 is a valve for releasing the steam in the pan 10 to the outside when the pressure in the pan 10 is abnormally increased. An annular seal member 12 a that is in contact with the upper opening 10 a of the pan 10 is attached to the outer peripheral portion of the inner lid 12. A locking portion (not shown) that is detachably locked to the outer lid 15 is provided on the outer peripheral portion of the inner lid 12. As shown in FIG. 3, the pressure valve 13 is provided on the valve seat 13 a so as to close the steam discharge hole 131 and the valve seat 13 a in which the steam discharge hole 131 that communicates the inside of the pan 10 and the lid 11 is formed. A metal ball 14 to be placed and a cover 13b that restricts the movement of the ball 14 and holds it on the valve seat 13a are provided. The ball 14 has a predetermined weight and closes the steam discharge hole 131 by its own weight. As shown in FIG. 3, a steam sensor Sen2 that detects the steam temperature is attached to the cover 13b.

  The outer lid 15 includes a lid heater H3, a lock mechanism 16, and a pressure valve opening / closing mechanism 19. The lid heater H <b> 3 is a heater that heats the inside of the pan 10 from the upper opening 10 a side of the pan 10. In the first embodiment, the pot bottom heater H1, the side heater H2, and the lid heater H3 constitute a heating device that heats the pot 10.

  As shown in FIG. 2, the lock mechanism 16 includes a swing rod 17 that is swingably fixed to the frame of the outer lid 15. A locking claw 17 a that is locked to the locking member 8 described above is provided at one end of the swing rod 17. A release button 17b for releasing the locking between the locking member 8 and the locking claw 17a is provided at the other end of the swing rod 17. When the locking claw 17 a is locked to the locking member 8, the lid 11 is held at a position where the upper opening 10 a of the pan 10 is closed. On the other hand, when the release button 17b is pressed and the engagement between the engagement claw 17a and the engagement member 8 is released, the lid body 11 moves to the open position (position where the upper opening 10a of the pan 10 is opened). It becomes possible. In addition, the outer lid 15 supports the rotation of the lid 11 in the opening direction around the hinge pin 91 of the hinge member 9 and also supports a spring pivot mechanism (not shown) that holds the lid 11 in the open position. Is provided.

  The pressure valve opening / closing mechanism 19 adjusts the pressure in the pan 10 by switching the opening / closing state of the steam discharge hole 131 by the pressure valve 13. As shown in FIG. 3, the pressure valve opening / closing mechanism 19 operates with a cylinder 20, a plunger 21 that moves forward and backward within the cylinder 20, an operating rod 22 attached to the tip of the plunger 21, and one end of the cylinder 20. And a spring body 25 provided between the flange 22.

  The cylinder 20 incorporates an electromagnetic coil (not shown) wound in a cylindrical shape. The plunger 21 moves forward and backward in the cylinder 20 depending on whether or not the electromagnetic coil is excited. The spring body 25 is composed of, for example, an extension coil spring. The operating rod 22 is supported by the cover 13b of the pressure valve 13 through a sealing member 23 having elasticity.

  When the electromagnetic coil of the cylinder 20 is not excited, the plunger 21 is urged away from the cylinder 23a by the elastic force of the spring body 25 as shown in FIG. At this time, the ball 14 is pushed away from the steam discharge hole 131 through the operating rod 22, and the steam discharge hole 131 is opened. On the other hand, the plunger 21 is pulled into the cylinder 20 against the elastic force of the spring body 25 when the electromagnetic coil of the cylinder 20 is excited. At this time, the ball 14 moves along the inclined surface provided in the valve seat 13a by its own weight, returns to the steam discharge hole 131, and the steam discharge hole 131 is closed.

  The outer lid 15 is formed with a recess 24 'for detachably attaching a storage tank 24 for temporarily storing rice balls (viscous rice broth) generated in the rice cooking process. A mounting hole 15a is provided in the recess 24 '. The storage tank 24 is press-fitted and fixed in the mounting hole 15a. As shown in FIG. 2, the storage tank 24 has a discharge cylinder 24a for discharging steam discharged from the steam discharge hole 131 of the pressure valve 13, an empty chamber 24b for temporarily storing a rice cake, and discharges steam to the outside. And a steam discharge port 24c. A return valve V2 is provided at the bottom of the empty chamber 24b to return the stored rice ball into the pot 10. When the steam is discharged from the steam discharge hole 131 of the pressure valve 13, the rice ball is discharged from the steam discharge hole 131 together with the steam and temporarily stored in the empty chamber 24 b of the storage tank 24. When the amount of rice stored in the vacant chamber 24b reaches a predetermined amount, the return valve V2 is opened and returned to the pot 10. The outer surface of the outer lid 15 is covered with a decorative cover 18.

  Next, the configuration and control operation of the control unit 30 will be described in more detail with reference to FIG. FIG. 4 is a block diagram illustrating a configuration of the control unit 30.

  As shown in FIG. 4, the control unit 30 includes a CPU 30 a that performs various arithmetic processes, a ROM 30 b and a RAM 30 c that store various data, and a rice cooking menu detection circuit 30 d that detects the rice cooking menu selected on the operation panel 5 a. And. The control unit 30 also includes a valve opening / closing timer 30e for setting the opening / closing time of the pressure valve 13, a counter 30f for counting the number of times the pressure valve 13 is opened / closed, and the heating temperature and heating of the pot 10 by the heaters H1, H2, H3. And a heating control circuit 30g for controlling time. The control unit 30 further includes a display panel control circuit 30h that controls a display screen displayed on the display panel 5b, and a pressure valve opening / closing mechanism drive circuit that controls the opening / closing timing of the pressure valve 13 by driving the pressure valve opening / closing mechanism 19. 30i. Each component of the control unit 30 and the circuits 30a to 30i are mounted on a control circuit board. In the ROM 30b and the RAM 30c, rice cooking programs corresponding to various rice cooking menus are stored. Here, the rice cooking program is a process of cooking rice in which energization time, heating temperature, heating time, heating output, etc. are determined in advance in each process in order to perform the four steps of water absorption, temperature rise, boiling maintenance and steaming in order. Refers to the procedure. The control part 30 controls the drive of each part and each apparatus based on the rice cooking menu selected with the operation panel 5a and the detection temperature of each sensor Sen1, Sen2, and performs a rice cooking process.

  In addition, the control unit 30 controls the pressure valve opening / closing mechanism 19 so that the steam discharge hole 131 is switched from the closed state to the open state at least once in each of the first half and the second half of the boiling maintenance step. Here, “the first half of the boiling maintenance process” refers to a period in which a sufficient amount of water is present in the pan 10 to cause a bumping phenomenon. For example, the period required for the boiling maintenance process is equally divided into two ( First half, second half). The “first half of the boiling maintenance step” may be the first half period when the period required for the boiling maintenance step is equally divided into three (first half, middle stage, second half). In the first embodiment, the “first half of the boiling maintenance process” is, for example, 64 seconds from the start of the boiling maintenance process. In addition, “the latter half of the boiling maintenance process” means that the water in the pot 10 is almost lost, but a sticky film is generated along the wall surface of the pot 10. For example, it refers to a period of the latter half when the period required for the boiling maintenance step is equally divided into two (first half, second half). The “second half of the boiling maintenance process” may be a second half period when the period required for the boiling maintenance process is equally divided into three (first half, middle stage, second half). In the first embodiment, the “second half of the boiling maintenance process” is, for example, about 2 minutes before the end of the boiling maintenance process.

  By switching the steam discharge hole 131 from the closed state to the open state in the first half of the boiling maintenance step, the pressure in the pan 10 is reduced at a stretch. Thereby, a bumping phenomenon occurs in the pan 10, and the cooked rice in the pan 10 is stirred. As a result, heat is efficiently transmitted to the cooked rice, and rice with good taste can be cooked. In addition, what is necessary is just to reduce the pressure in the pan 10 0.05 atmospheres or more, for example, in order to generate a bumping phenomenon in the pan 10.

  In addition, when the steam discharge hole 131 is switched from the closed state to the open state in the second half of the boiling maintenance step, the pressure in the pan 10 is reduced at a stretch. Thereby, the film | membrane of the tobe produced along the wall surface of the pan 10 collapse | crumbles, and it generate | occur | produces from the whole pan 10 so that a boiling bubble may pass between rice grains. That is, it is possible to form a trace of boiling bubbles, generally called “crab hole”, on the entire surface of the rice. As a result, it is possible to efficiently transfer heat to each rice grain and to make the rice grain stand up, and to cook rice that is excellent in taste and sight. In addition, what is necessary is just to reduce the pressure in the pan 10 0.05 atmospheres or more, for example, in order to break down the film of the tobe generated along the wall surface of the pan 10.

  In the first embodiment, the control unit 30 sets the time during which the steam discharge hole 131 is in the closed state immediately before switching the steam discharge hole 131 to the open state, in the latter half of the boiling maintenance process than in the first half of the boiling maintenance process. The pressure valve opening / closing mechanism 19 is controlled so as to be longer. Thereby, the fall amount of the pressure in the pan 10 by switching the steam discharge hole 131 from the closed state to the open state is larger in the latter half of the boiling maintenance step than in the first half of the boiling maintenance step. That is, in the first half of the boiling maintaining step, it is possible to suppress the rice rice grains from being rubbed by suppressing the stirring force of the cooked rice due to the bumping phenomenon being too strong. Therefore, it can suppress that stickiness arises on the surface of the cooked rice. On the other hand, in the latter half of the boiling maintenance step, the amount of boiling bubbles passing between the rice grains can be increased, so that heat can be more efficiently transmitted to each rice grain and the rice grain can be made to stand.

  In addition, as for the control part 30, the difference of the fall amount of the pressure in the pan 10 in the second half of a boiling maintenance process and the fall amount of the pressure in the pan 10 in the first half of a boiling maintenance process is 0.02 atmospheres or more (more preferably, It is preferable to control the pressure valve opening / closing mechanism 19 to be 0.03 atm or higher. That is, the pressure fluctuation in the pan 10 in the first half of the boiling maintenance process is reduced (the stirring force of the cooked rice is reduced), while the pressure fluctuation in the pan 10 in the second half of the boiling maintenance process is increased (generation of boiling bubbles). Is preferable). Thereby, while suppressing that the stirring force of the to-be-cooked rice due to a bumping phenomenon is too strong, the rice cake produced along the wall surface of the pan 10 is more reliably broken, and the amount of boiling bubbles passing through the rice grains is increased. can do.

  Next, with reference to FIG.5 and FIG.6, the rice cooking process in case a white rice and normal rice cooking course is selected as a rice cooking menu with the operation panel 5a is demonstrated. FIG. 5 is a graph showing changes in temperature and pressure in the pan 10 in the rice cooking process of the white rice / normal rice cooking course. FIG. 6 is a flowchart showing the control operation of the control unit 30 in the water absorption process and the temperature raising process of the white rice / normal rice cooking course.

(A) Water absorption process I
When the start key is pressed after the white rice / normal rice cooking course is selected on the operation panel 5a, the water absorption process I is executed first. The water absorption step I is a step of immersing the rice in water at a temperature lower than the gelatinization temperature so that the rice can be sufficiently gelatinized in the subsequent steps, and allowing the rice to absorb water in advance. In this water absorption step I, the control unit 30 raises the temperature of the water in the pot 10 to the water absorption temperature θ2 (for example, 55.2 ° C.), and then maintains the temperature after the temperature increase. The pan bottom heater H1 is controlled based on the detected temperature of the sensor Sen1.

  Further, when the water absorption process I is started, the pressure valve 13 is closed (a state where the steam discharge hole 131 is closed by the ball 14) (step S101). At the same time or thereafter, power supply to the pan bottom heater H1 is started (step S102). At this time, a water absorption timer (not shown) provided in the control unit 30 starts measuring time (step S103). Here, the time taken by the water absorption timer is referred to as the water absorption time Tk. When the water absorption time Tk reaches a time t1 (for example, 15 minutes) set in advance according to the rice cooking menu, the process proceeds to the temperature raising step II (step S104). At this time, the pressure valve 13 remains closed.

(B) Temperature raising step II
The temperature raising step II is a step in which the pot 10 is heated at a stretch with a strong fire to bring the water in the pot 10 to a boiling maintenance state (about 100 ° C.). In this temperature raising step, the control unit 30 continues to supply power to all of the pot bottom heater H1, the side heater H2, and the lid heater H3. Thereby, the pan bottom temperature K1 of the pan 10 rises with a steep slope as shown in FIG. Steam is generated in the pan 10 by the rise of the pan bottom temperature K1. The steam temperature Sen2 is detected by the steam sensor Sen2 (step S105). The steam temperature K2 rises slightly later than the pan bottom temperature K1. In addition, when steam is initially generated, there is a slight gap between the upper opening 10a of the pan 10 and the seal member 12a. For this reason, steam leaks from the gap and the pressure in the pan 10 does not increase. That is, the pressure valve 13 is maintained in a closed state for a predetermined time after shifting to the temperature raising step II, but the pressure in the pan 10 does not increase. On the other hand, the pressure in the pan 10 rises after a lapse of a predetermined time from the transition to the temperature raising step II. At the end of the temperature raising step II, the pressure in the pan 10 is equal to or higher than atmospheric pressure (for example, 1.15 atm). It becomes. When power supply to the pan bottom heater H1, the side heater H2, and the lid heater H3 is continued and the steam temperature K2 reaches a predetermined boiling temperature θ3 (for example, 75 ° C.), the process proceeds to the boiling maintenance process III (step S106).

  When the amount of cooked rice is small, the rate of increase of the steam temperature K2 increases, so the time until the steam temperature K2 reaches the boiling temperature θ3 is short. On the other hand, when the amount of cooked rice is large, the rate at which the steam temperature K2 increases is slow, so the time until the steam temperature K reaches the boiling temperature θ3 is long. That is, the time t2 of the temperature raising process II changes according to the amount of rice cooking. The time t2 in the temperature raising step II is, for example, 3 minutes to 10 minutes.

(C) Boiling maintenance process III
Boiling maintenance process III is a process which maintains the boiling state of the water in the pan 10, gelatinizes rice starch, and raises the gelatinization degree to about 50% to 80%. In the boiling maintenance process III, the control unit 30 supplies power intermittently to the pot bottom heater H1, the side heater H2, and the lid heater H3 so as to maintain the boiling state of the water in the pot 10. In addition, immediately after transfer to the boiling maintenance process III, the inside of the pan 10 is in a mixed state of boiling steam and compressed air, and has not reached a complete boiling state. Only in the middle stage of the boiling maintenance process III, the inside of the pan 10 is filled with only boiling steam and becomes a complete boiling state.

  In addition, the control unit 30 controls the pressure valve opening / closing mechanism 19 to switch the steam discharge hole 131 from the closed state to the open state a plurality of times (for example, three times) in the first half of the boiling maintenance step III. Thereby, the pressure in the pan 10 drops at a stretch from about 1.15 atm to near atmospheric pressure, a bumping phenomenon occurs in the pan 10, and the cooked rice in the pan 10 is agitated. In addition, in order to reduce the pressure in the pan 10 from about 1.15 atm to about atmospheric pressure, the time for maintaining the steam discharge hole 131 in the open state is, for example, 4 seconds.

  The control unit 30 controls the pressure valve opening / closing mechanism 19 to switch the steam discharge hole 131 from the open state to the closed state after maintaining the steam discharge hole 131 in the open state for a predetermined time (for example, 4 seconds). Thereafter, the heating of the pan 10 is continued for a predetermined time (for example, 16 seconds), so that the pressure in the pan 10 returns to about 1.15 atm. The predetermined time until the pressure in the pan 10 returns from the vicinity of atmospheric pressure to about 1.15 atmosphere is experimentally obtained in advance. Note that when the steam discharge hole 131 is opened, the rice bowl generated in the pan 10 is discharged to the storage tank 24 through the steam discharge hole 131 and temporarily stored. Thereafter, when the steam discharge hole 131 is closed, the rice cake temporarily stored in the storage tank 24 returns to the pot 10.

  When the steam discharge hole 131 is switched from the last closed state to the open state in the first half of the boiling maintenance process III and the pressure in the pan 10 decreases to near atmospheric pressure, the control unit 30 opens the steam discharge hole 131. The pressure valve opening / closing mechanism 19 is controlled to switch from the state to the closed state. Thereafter, the heating of the pan 10 is continued for a predetermined time (for example, longer than 16 seconds), so that the pressure in the pan 10 rises to about 1.20 atm.

  Further, the control unit 30 controls the pressure valve opening / closing mechanism 19 to switch the steam discharge hole 131 from the closed state to the open state at least once in the second half of the boiling maintenance step III. As a result, the pressure in the pan 10 drops from about 1.20 atm to near atmospheric pressure, the film of the rice cake generated along the wall surface of the pan 10 collapses, and the pan 10 so that the boiling bubbles pass between the rice grains. It originates from the whole.

  The control unit 30 controls the pressure valve opening / closing mechanism 19 to switch the steam discharge hole 131 from the open state to the closed state after maintaining the steam discharge hole 131 in the open state for a predetermined time (for example, 4 seconds). Thereafter, the heating of the pan 10 is continued for a predetermined time (for example, longer than 16 seconds), so that the pressure in the pan 10 returns to about 1.20 atm.

  In the boiling maintenance step III, a large amount of steam at about 100 ° C. is generated to continuously boil water. This steam is discharged to the outside of the rice cooker through the steam discharge hole 131 or the like. Thereby, when most of the water in the pot 10 runs out, the temperature of the bottom in the pot 10 rises above the boiling point of water. When the bottom sensor Sen1 detects that the temperature of the bottom of the pan 10 has reached the boiling point or higher (eg, 130 ° C.), the process proceeds to the steaming process.

(D) Steaming process The steaming process is a process of evaporating excess water using preheating and raising the gelatinization temperature of rice to nearly 100%. In this steaming process, the control unit 30 controls the heaters H1 to H3 so as to stop the heating of the pan 10, and controls the pressure valve opening / closing mechanism 19 so as to switch the steam discharge hole 131 from the closed state to the open state. To do. Then, when predetermined time (for example, 4 minutes) passes since the start of a steaming process, the control part 30 will control each heater H1-H3 so that the pan 10 may be heated. Thereby, the excess water | moisture content adhering to the surface of rice is evaporated (cooking). Then, when predetermined time (for example, 3 minutes) passes, the control part 30 will control each heater H1-H3 so that the heating of the pan 10 may be stopped. Thereafter, when a predetermined time (for example, 6 minutes) elapses from the start of the steaming process, the steaming process is terminated. That is, the rice cooking process is terminated. In addition, the heat retention process may be performed after the rice cooking process is completed.

  According to the pressure rice cooker according to the first embodiment, the steam discharge hole 131 is switched from the closed state to the open state at least once in the first half and the second half of the boiling maintenance step III. Moreover, according to the pressure type rice cooker which concerns on this 1st Embodiment, the boiling maintenance process rather than the first half of the boiling maintenance process III is the time when the steam discharge hole 131 just before switching the steam discharge hole 131 to an open state is closed. The latter half of III is longer. Thereby, as above-mentioned, the stickiness of the surface of rice can be suppressed and the taste of rice can be improved further.

(Second Embodiment)
Next, the pressure type rice cooker which concerns on 2nd Embodiment of this invention is demonstrated. FIG. 7 is a graph showing changes in temperature and pressure in the pan in the rice cooking process of the pressure rice cooker according to the second embodiment of the present invention. The difference between the pressure rice cooker according to the second embodiment and the pressure rice cooker according to the first embodiment is that the control unit 30 opens the steam discharge hole 131 during the temperature raising step II, and boils. The point is to control the pressure valve opening / closing mechanism 19 so that the steam discharge hole 131 is closed at the start of the maintenance process III and the open state of the steam discharge hole 131 in the latter half of the boiling maintenance process III is lengthened.

  In the second embodiment, since the steam discharge hole 131 is opened during the temperature raising step II, it is possible to prevent pressure from being applied to the cooked rice in the temperature raising step II. Thereby, it is possible to cook rice that is light and less sticky.

  In the second embodiment, the steam discharge hole 131 is closed at the start of the boiling maintenance process III, and the time for the steam discharge hole 131 to be open in the latter half of the boiling maintenance process III is lengthened. More specifically, the steam discharge hole 131 is closed at the start of the boiling maintenance step III, and the heating of the pan 10 is continued for a predetermined time (for example, 16 seconds), whereby the pressure in the pan 10 is reduced to about 1. The pressure is increased to 15 atmospheres. After that, as in the first embodiment, the steam discharge hole 131 is switched between open and closed states to cause a bumping phenomenon in the pan 10. Further, in the latter half of the boiling maintenance step III, the steam discharge hole 131 is changed from the open state to the closed state, the atmospheric pressure in the pan 10 is increased to about 1.20 atm. The open state is maintained. Thereby, in boiling maintenance process III, the time which pressure is applied to a to-be-cooked rice can be shortened, and it can cook rice which is light with little stickiness.

(Third embodiment)
Next, the pressure type rice cooker which concerns on 3rd Embodiment of this invention is demonstrated. FIG. 8 is a graph showing changes in temperature and pressure in the pan in the rice cooking process of the pressure rice cooker according to the third embodiment of the present invention. The difference between the pressure rice cooker according to the third embodiment and the pressure rice cooker according to the first embodiment is further provided with a pressure sensor (not shown) for detecting the pressure in the pan 10, and the control unit 30. Is a point that controls the pressure valve opening / closing mechanism 19 based on the detected pressure of the pressure sensor.

  According to the pressure rice cooker according to the third embodiment, switching of the open / close state of the steam discharge hole 131 can be performed at an optimal timing, and variations in the quality of cooked rice can be suppressed. In addition, a pressure sensor is attached to the cover body 11, for example.

(Fourth embodiment)
Next, the pressure type rice cooker which concerns on 4th Embodiment of this invention is demonstrated. FIG. 9 is a graph showing changes in temperature and pressure in the pan in the rice cooking process of the pressure rice cooker according to the fourth embodiment of the present invention. The difference between the pressure rice cooker according to the fourth embodiment and the pressure rice cooker according to the first embodiment is that the time of the water absorption process corresponding to the rice cooking menu selected on the operation panel 5a is the standard rice cooking menu. When the control unit 30 controls the pressure valve opening / closing mechanism 19 to switch the steam discharge hole 131 from the closed state to the open state, the number of times of switching from the closed rice cooking menu is increased. It is a point.

  Here, the “standard rice cooking menu” is, for example, the aforementioned white rice / normal rice cooking course. When it is desired to cook rice softer than the standard, it is effective to sufficiently immerse the water up to the center of the rice grain in the water absorption process. For this reason, the time of the water absorption process corresponding to the white rice / soft rice cooking course, which is a rice cooking menu for softly cooking rice, is set longer than the time of the water absorption process corresponding to the white rice / normal rice cooking course (for example, 25 minutes). ing. However, when the time of the water absorption process is lengthened, sticking of rice occurs along the wall surface of the pan 10 in the temperature raising process, and the boiling foam may pass through the rice grains vigorously in the boiling maintenance process due to the sticking. It may not be possible. In this case, heat cannot be efficiently transferred to the rice.

  Therefore, in the pressure rice cooker according to the fourth embodiment, when the rice cooking menu selected on the operation panel 5a is the white rice / soft rice cooking course, the steam discharge hole 131 is opened from the closed state during the boiling maintenance process. The number of times of switching to the state is increased (for example, 5 times) compared to the white rice / normal rice cooking course. Thereby, the sticking of rice can be broken and the boiling bubbles can pass through between the rice grains vigorously in the boiling maintenance step.

  Since the pressure type rice cooker according to the present invention can suppress the stickiness of the surface of the rice and further improve the taste of the rice, it is useful as a pressure type rice cooker for home use and business use.

DESCRIPTION OF SYMBOLS 1 Pressure type rice cooker 2 Rice cooker main body 3 Exterior case 4 Inner case 5 Display operation part 6 Frame cover 7 Frame cover reinforcement member 8 Locking member 9 Hinge part 10 Pan 11 Lid 12 Inner lid 13 Pressure valve 14 Ball 15 Outer lid DESCRIPTION OF SYMBOLS 16 Lock mechanism 17 Oscillating rod 18 Cosmetic cover 19 Pressure valve opening / closing mechanism 20 Cylinder 21 Plunger 22 Actuation rod 23 Seal member 24 Storage tank 25 Spring body 30 Control part 131 Steam discharge hole I Water absorption process II Temperature rising process III Boiling maintenance process H1 Pan bottom heater H2 Side heater H3 Cover heater Sen1 Bottom sensor (pan temperature detector)
Sen2 steam sensor

Claims (9)

A pot for storing cooked rice containing water and rice;
A heating device for heating the pan;
A lid that closes the opening of the pan;
A pressure valve that opens and closes a steam discharge hole communicating the inside of the pan and the lid;
A pressure valve opening and closing mechanism that adjusts the pressure in the pan by switching the opening and closing state of the steam discharge hole by the pressure valve;
A controller that controls the heating device and the pressure valve opening / closing mechanism to perform a rice cooking process including a water absorption process, a temperature rising process, and a boiling maintaining process;
A pressure rice cooker comprising:
The control unit controls the pressure valve opening / closing mechanism to switch the steam discharge hole from a closed state to an open state at least once in each of the first half and the second half of the boiling maintenance step, and the steam discharge hole While controlling the pressure valve opening and closing mechanism so that the second half of the boiling maintenance step is longer than the first half of the boiling maintenance step, the time when the steam discharge hole immediately before switching to the open state is closed ,
The control unit controls the pressure valve opening and closing mechanism so that the steam discharge hole is opened during the temperature raising step and the steam discharge hole is closed at the start of the boiling maintenance step. rice cooker.   The control unit is configured such that the amount of pressure decrease in the pan caused by switching the steam discharge hole from the closed state to the open state is greater in the second half of the boiling maintenance step than in the first half of the boiling maintenance step. The pressure rice cooker according to claim 1, which controls the pressure valve opening / closing mechanism.   The pressure-type rice cooker according to claim 2, wherein the control unit controls the pressure valve opening / closing mechanism so that a pressure drop amount in the pan in the first half of the boiling maintenance step is 0.05 atm or more.   The control unit is configured so that a difference between a decrease amount of the pressure in the pan in the second half of the boiling maintenance step and a decrease amount of the pressure in the pan in the first half of the boiling maintenance step is 0.02 atm or more. The pressure-type rice cooker of Claim 2 or 3 which controls a pressure valve opening / closing mechanism.   The control unit controls the pressure valve opening / closing mechanism in the first half of the boiling maintenance step so that the pressure in the pan is reduced at a stroke so that a sudden boiling phenomenon occurs in the pan, and the second half of the boiling maintenance step. The pressure valve opening / closing mechanism is controlled so that the pressure in the pan is lowered at a stretch so that boiling bubbles that pass between the rice grains are generated in the pan in the pan. Type rice cooker.   The first half of the boiling maintenance step is a first half period when the period required for the boiling maintenance step is equally divided into two, and the second half of the boiling maintenance step is equally divided into two times for the boiling maintenance step. The pressure-type rice cooker as described in any one of Claims 1-5 which is the period of the latter half of time.   The first half of the boiling maintenance step is a first half period when the period required for the boiling maintenance step is equally divided into three, and the second half of the boiling maintenance step is equally divided into three periods required for the boiling maintenance step. The pressure-type rice cooker as described in any one of Claims 1-5 which is the period of the latter half of time. A pressure sensor for detecting the pressure in the pan;
Wherein, based on the detected pressure of the pressure sensor, controls the pressure valve opening and closing mechanism, a pressure type rice cooker according to any one of claims 1-7. An operation unit that can select one rice cooking menu from a plurality of rice cooking menus including a standard rice cooking menu,
When the time of the water absorption process corresponding to the rice cooking menu selected by the operation unit is longer than the time of the water absorption process corresponding to the standard rice cooking menu, the control unit performs the pressure during the boiling maintenance process. The pressure rice cooker according to any one of claims 1 to 8 , wherein the number of times of switching the steam discharge hole from a closed state to an open state by controlling a valve opening / closing mechanism is larger than that in the standard rice cooking menu.

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