JP4218612B2 - rice cooker - Google Patents

Description

  The present invention relates to a rice cooker used for general home use or business use.

  In recent years, rice cookers using electromagnetic induction heating have become widespread in the market. Conventional rice cookers that use electromagnetic induction heating (induction heating rice cookers) have an induction heating coil on the outside of the pan bottom, and use the magnetic force generated from the induction heating coil to heat the pan itself. You can cook plump and delicious rice compared to the example rice cooker.

  On the other hand, in order to improve the taste of rice, rice cookers that determine the amount of rice and water in the pan (the amount of cooked rice) and control the amount of heating according to the amount of cooked rice have become widespread. Conventionally, a method is known in which the amount of cooked rice is determined from the rate of temperature rise of a pan during heating (for example, when boiling after rice is absorbed at a predetermined temperature). However, in this case, the thermal power control is impossible until the temperature reaches a predetermined value and the amount of cooked rice is determined. Therefore, when the amount of cooked rice is small, the water boils before water absorption is sufficiently performed, and the core remains in the rice, and the rice may become hard.

Japanese Patent Publication No. 1-272724 discloses a conventional rice cooker. The rice cooker of the conventional example detects the weight of the inner pot (total weight of the inner pot, water and rice) by the weight detection means at the same time as the start of rice cooking, determines the amount of rice cooking, and the electric energy of the heater during cooking (thermal power) To control. Therefore, the thermal power control commensurate with the amount of cooked rice becomes possible at the start of cooking, and delicious rice can be cooked.
Japanese Examined Patent Publication No. 1-2724

  A conventional rice cooker disclosed in Japanese Patent Publication No. 1-272724 has a main body, a bottom frame, and a bottom lid that is inserted inside the bottom frame. When the pan is stored in the main body, the distance between the electrodes attached to the bottom frame and the bottom lid changes in proportion to the total weight of the pan and the main body. A change in capacitance between electrodes is detected as a change in oscillation state, and the amount of rice cooked is detected.

  When attaching the same weight detection means as the conventional rice cooker to the induction heating rice cooker, the following problems occurred. In an induction heating rice cooker, when cooking rice, the pan itself is heated to a high temperature to cause convection of water in the pan, and the rice is heated by heat conduction by the convection. Therefore, in order to uniformly heat the rice and water in the pan and not cause uneven cooking, the positional relationship between the pan and the induction heating coil is fixed to an optimal state, and a predetermined state is determined according to the amount of rice cooked. It is necessary to cause convection of strength in the pan. For this reason, the induction heating coil often has a three-dimensional complicated shape. On the other hand, a storage unit (comprising an upper frame and an upper coil base) in which an induction heating coil is built is usually produced from a resin in view of moldability and mass productivity. Since the pot becomes hot and the heat resistance of the resin is not so high, in general, the induction heating rice cooker has a pan that is horizontally suspended at the upper end of the storage part by its flange, etc., and there is a gap between the pot and the storage part . Therefore, the same weight detection means as the conventional rice cooker could not be attached to the induction heating rice cooker.

  Therefore, in the induction heating rice cooker, the structure which supports the substantially center part of a pan with the detection body linked with the weight detection means which detects the gross weight with the food put into the pan is taken. By taking this configuration, the distance between the pan and the induction heating coil is kept constant, and excellent rice cooking performance can be exhibited. “The total weight of the pot and the food in the pot” means the total weight of the object including at least the pot and the food in the pot.

  In addition to the above configuration, the detection body has a cylindrical shape, and has a temperature detection means for detecting the temperature of the pan inside thereof, thereby detecting the temperature of the pan with a small, light and inexpensive configuration, And the total weight of the food in the pan can be measured at the substantially central portion of the outer bottom of the pan.

  However, when the lead wire drawn out from the temperature detection means touches the storage portion or the weight detection element, there is a possibility that an error may occur in the weight detection due to the elastic stress of the lead wire.

  The present invention solves the above-mentioned conventional problems, and provides a rice cooker that realizes accurate weight detection of the total weight of the cooked food and realizes appropriate thermal power control according to the weight of the cooked food. For the purpose.

  In order to solve the above-mentioned problems, a main body having an open top surface, a pan that is detachably stored in a storage portion of the main body, a lid that covers the storage portion so as to be openable and closable, and induction heating means that induction heats the pan. A weight detection element that is directly or indirectly attached to the storage unit, a sensor base that is directly attached to the weight detection element, and a sensor base that is directly attached to the sensor base, A weight detecting means for detecting a total weight of the pot and the food put in the pot by the weight detecting element through the detecting body, and the weight detecting means. A controller that calculates the weight of the cooked food based on the output signal and controls the energization rate and / or the energization amount to the induction heating means according to the weight of the cooked food, and the detector has a cylindrical shape. Has a front side inside the detection body A temperature detection means for detecting the temperature of the pan is provided, the temperature detection means is provided with a temperature detection element, a lead wire is drawn from the temperature detection element, and the lead wire is fixed to the sensor base. It is a rice cooker.

  As a result, errors in weight detection due to changes in the elastic stress of the lead wire due to the loading and unloading of the pot and the heat of rice cooking can be reduced, and the weight detection of the total weight of the cooked food can be performed with high accuracy and cooking. The rice cooker which implement | achieves suitable thermal power control according to the weight of the thing can be provided.

  The rice cooker of the present invention can reduce the error of weight detection due to the elastic stress change of the lead wire due to the putting in and out of the pot and the heat of rice cooking, realizing the accurate weight detection of the total weight of the cooked food And the rice cooker which implement | achieves suitable thermal-power control according to the weight of the foodstuff can be provided.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that specifically show the best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
The rice cooker of Embodiment 1 of this invention is demonstrated using FIG.1, FIG.2 and FIG.3.

  FIG. 1 is a partially cutaway side view of a rice cooker according to an embodiment of the present invention. A sectional view is shown in the broken part. In order to simplify the drawing, lead wires and the like for electrical connection are omitted. In FIG. 1, 10 is a body (main body) of a rice cooker. The body 10 is provided with a lid 20 that covers the upper surface thereof so as to be freely opened and closed. The housing portion 30 of the body 10 includes an upper frame 32 and a lower coil base 31. Reference numeral 12 denotes a pan formed of a magnetic material such as stainless steel or iron. The pan 12 has a flange 121 protruding outward from the upper end opening, and is detachably stored in the storage unit 30 by placing the flange 121 in a state of being lifted from the upper end of the upper frame 32. The pan 12 has a gap with the storage portion 30 during storage. An induction heating coil 13 that induction-heats the pan 12 is disposed at a portion of the coil base 31 that faces the bottom of the pan 12. The induction heating coil 13 includes an outer coil disposed outside the bottom surface of the coil base 31 and an inner coil disposed inside the bottom surface. Each induction heating coil is a winding having a center substantially directly below the center of the bottom of the pan 12. Reference numeral 14 denotes a circuit board. A microcomputer (not shown) is mounted on the circuit board 14. The microcomputer controls the current for generating an alternating magnetic field in the induction heating coil 13 by software. The rice cooker of Embodiment 1 induction-heats the pan 12 and heats the food 19 in the pan 12. The cooked food 19 is rice before cooking rice, water, cooked rice, or the like. Reference numeral 21 denotes a base fixed with a gap at the bottom of the coil base 31. The base 21 is provided with weight detecting means 40 for detecting the weight of the pan 12, pot detecting means 16 for detecting the presence or absence of the pot 12, and temperature detecting means 52 for detecting the temperature of the pot 12. The configuration of each detection means will be described with reference to FIGS. FIG. 2 is an exploded perspective view of main parts of the rice cooker according to the first embodiment.

  The weight detection means 40 includes a load cell 41, a sensor base (insulating member) 42, and a contact tube (detecting body) 43. The load cell 41 is a robust type load transducer (weight detection element). The load cell 41 has a screw hole 411 at one end and a screw hole 412 at the other end. A thin plate 211 having a screw hole 212 is attached to the base 21. One end of the load cell 41 is screwed to the base 21 via a screw hole 212 and a screw hole 411. The other end of the load cell 41 has a gap with respect to the base 21. A resistance wire strain gauge 413 is attached to the load cell 41. A change in resistance of the strain gauge 413 when the load cell 41 is bent by a load is taken out as an electrical signal by the bridge circuit.

  Reference numeral 42 denotes a resin sensor base. The load cell 41 is fitted into the recess 421 of the sensor base 42. The sensor base 42 is screwed to one end of the load cell 41 through a screw hole 422 and a screw hole 412.

  Reference numeral 43 denotes a contact tube (detecting body) formed of aluminum having a thickness of 2 mm. The contact tube 43 has two claw portions 431 facing the lower side. The stopper cylinder 43 is fixed to the sensor base 42 by passing the claw portion 431 through the stopper cylinder fixing hole 423 of the sensor base 42 and bending it. The contact tube 43 has a flange 432 protruding inward at the upper end. An induction heating coil 13 is disposed outside the bottom surface of the coil base 31. The contact cylinder 43 is passed through one through hole provided in the central portion of the bottom of the coil base 31 (the central portion of the induction heating coil 13 where the induction heating coil 13 is not disposed). The The upper end of the contact tube 43 is higher than the inner bottom portion of the coil base 31 (FIG. 1). The weight detecting means 40 measures and supports the weight of the pan 12 only at the substantially central portion of the outer bottom thereof. Therefore, the weight detection means 40 can be attached without interfering with the induction heating coil 13. Since the pan 12 supported by the center part of the bottom is stably disposed in the storage unit 30, the induction heating coil 13 can heat the pan 12 appropriately and stably.

  The temperature detection means 52 has two collars 521 facing the upper part, and is inserted into the contact tube 43 from the lower side. The outer diameter of the collar 521 is substantially the same as the inner diameter of the contact cylinder 43, and the temperature detection means 52 does not come out from the contact cylinder 43. Further, a spring 51 is inserted between the contact tube 43 and the temperature detection means 52. The spring 51 abuts on the lower surface of the collar 521 and the sensor base 42 and urges the temperature detection means 52 so that the temperature detection means 52 is in close contact with the pan 12. An electrical signal corresponding to the temperature of the pan 12 detected by the temperature detection means 52 is input to the circuit board 14 via the lead wire 53 and the connector 54. The lead wire 53 is pulled out from the groove 424 of the sensor base 42 and fixed on the outer peripheral side surface of the sensor base 42.

  When there is no pan 12 in the storage unit 30, the upper surface of the collar 521 of the temperature detecting means 52 is in contact with the lower surface of the flange 432 of the abutting cylinder 43. The upper surface of the temperature detecting means 52 is located higher than the upper surface of the flange 432.

  When the pot 12 is stored in the storage section 30, the bottom of the pot 12 first comes into contact with the temperature detection means 52, and finally comes into contact with the temperature detection means 52 and the contact cylinder 43 (FIG. 1). Therefore, since the batting cylinder 43 supports the pan 12 at the center, the pan 12 does not tilt. The load cell 41 detects and outputs the total weight of the pan 12, the food 19, the sensor base 42, the spring 51, the temperature detection means 52, and the contact cylinder 43. The temperature detecting means 52 sinks into the contact tube 43 by the spring 51, and the upper surface thereof is in contact with the bottom of the pan 12 at the same height as the upper surface of the flange 432. The temperature detection means 52 contacts the bottom of the pan 12 with an appropriate pressure defined by the spring 51 without applying an excessive force.

  The pan detection means 16 is composed of a micro switch fixed to the base 21 (FIG. 1). When the pan 12 is stored in the storage unit 30, the bottom of the sensor base 42 comes into contact with the microswitch, and the pan detecting means 16 outputs an ON signal. The operation stroke of the micro switch is larger than the displacement amount of the sensor base 42 on which the pan 12 is placed. Thereby, even when the pan 12 is placed on the sensor base 42 and the micro switch is operated, the weight of the pan 12 supported by the micro switch is very small and does not affect the measurement value of the weight detection means 40. You may comprise so that a microswitch may not support the weight of the pan 12 more than fixed by driving a microswitch via an actuator (for example, the phosphor bronze board which has spring property).

  Electric signals from the temperature detection means 52, the pan detection means 16 and the weight detection means 40 (load cell 41) are input to the circuit board 14, respectively.

The microcomputer mounted on the circuit board 14 stores in advance a predetermined state (when there is no pan 12 and when an empty pan 12 is stored, the pan 12 containing the maximum amount of rice and water is stored. Output signal data (S1, S2, S3) of the load cell 41 at the time of When the magnitude of the output signal of the load cell 41 is S, the weight W of the food 19 in the pan 12 is
W = Wmax × (S−S2) / (S3−S2)
It becomes. However, Wmax is the maximum weight of the food 19 and is a known amount (a pot 12 containing the maximum amount of rice and water (the food 19), the sensor base 42, the spring 51, the temperature detection means 52, and the pad. This is the total weight of the cylinder 43 and a value corresponding to the output signal data S3 of the load cell 41). From this equation, the microcomputer calculates the weight of the cooked item 19 and estimates the amount of cooked rice.

  Operation | movement in the rice cooking process of the rice cooker of Embodiment 1 of this invention is demonstrated paying attention to the difference with the operation | movement of the conventional rice cooker which determines the amount of rice cooking by the temperature rise gradient of the temperature detection means 52 during rice cooking.

  The cooking process is predominately chronologically pre-cooked, cooked, boiled, cooked, and steamed. In the pre-cooking process, the rice and water in the pan are heated so that the temperature of the pan 12 becomes a temperature suitable for water absorption of rice (50 ° C.). Next, in the cooking step, the pan 12 is heated with a predetermined amount of heat until the temperature of the pan 12 reaches a predetermined value (100 ° C.). In a conventional rice cooker, the amount of cooked rice is determined based on the temperature rise rate at this time. In the boiling maintenance step, the rice and water are heated until the water in the pan 12 is exhausted and the temperature of the pan 12 reaches a predetermined value exceeding 100 ° C. Finally, in the steaming process, heating (cooking) according to the amount of cooked rice and stopping of heating are repeated a plurality of times during a fixed time.

  The pre-cooking process will be described. 6 (a) and 6 (b) show the pan bottom (solid line) and the center of the cooked food in the pre-cooking process when 1-cooked rice is cooked with the rice cooker of Embodiment 1 of the present invention and when 5 gogome is cooked ( The temperature shown by a broken line). FIG.6 (c) and (d) are the rice cookers of the prior art example which determines the amount of rice cooking in a cooking process, The pot bottom (solid line) in the pre-cooking process at the time of 1-cooking rice and 5-cooking rice The temperature of the center of the cooked product (broken line) is shown. The temperature of the pan bottom is detected by the temperature detecting means 52.

  The conventional rice cooker that determines the amount of cooked rice in the cooking step performs heating until the temperature detected by the temperature detecting means 52 becomes a temperature suitable for water absorption (50 ° C.) regardless of the amount of the cooked food 19. Thereafter, the temperature of the pan 12 is kept at 50 ° C. for a predetermined time (Ta), and the rice is absorbed. However, when the amount of cooked rice is large (FIG. 6 (d)), it takes time for the temperature of the whole cooked item 19 to reach 50 ° C., so the water absorption time at an appropriate temperature is insufficient. Therefore, the core remains in the rice.

  The rice cooker of Embodiment 1 of this invention changes the temperature at the time of water absorption (temperature detected by the temperature detection means 52) according to the quantity of the foodstuff 19. FIG. For example, when the amount of cooked rice is 1 go, heating is performed until the temperature detected by the temperature detecting means 52 reaches 50 ° C. Then, the temperature of the pan 12 is kept at 50 ° C. for a predetermined time (Ta), and the rice is absorbed (FIG. 6A). For example, when the amount of cooked rice is 5 go, heating is performed until the temperature detected by the temperature detecting means 52 reaches 60 ° C. And the temperature of the pan 12 is kept at 60 degreeC for predetermined time (Ta), and water is absorbed. Since the temperature of the central part of the cooked food 19 rises later than the outside temperature and reaches about 50 ° C., the rice can absorb water sufficiently.

  The cooking process will be described. In the conventional rice cooker that determines the amount of rice cooked in the cooking process, the pot 12 is kept at a predetermined temperature (100) with a predetermined heating power (the current conduction rate and / or the current conduction amount of the induction heating coil 13) regardless of the amount of the cooked food 19. C.). Therefore, when the amount of cooked rice is small, the rice is boiled too quickly and only the surface of the rice is gelatinized, leaving the core remaining. The rice cooker according to the first embodiment of the present invention changes the heating power (the energization rate and / or the energization amount of the induction heating coil 13) in the cooking process according to the amount of rice cooked. That is, control is performed to weaken the thermal power as the amount of cooked rice is small so that the time required for the cooking process is constant regardless of the amount of cooked rice.

  The rice cooker of Embodiment 1 of this invention calculates the amount of rice cooking correctly before a heating start, and performs the thermal power control according to the amount of rice cooking. Therefore, delicious rice can always be cooked regardless of the amount of cooked rice.

  In addition, it is good also as a control method which changes the time of pre-cooking instead of the temperature at the time of pre-cooking according to the amount of rice cooking.

  In the rice cooker of the present embodiment, the lead wire 53 is pulled out from the groove 424 of the sensor base 42 and fixed on the outer peripheral side surface of the sensor base 42, so that the lead wire 53 Error in weight detection due to elastic stress change can be reduced.

  Accordingly, it is possible to provide a rice cooker that realizes accurate weight detection of the total weight of the food 19 and realizes appropriate thermal power control according to the weight of the food 19.

  It should be noted that the same effect can be obtained even if the sensor base and the detection body are configured as a single body.

  The rice cooker according to the present invention is useful as a rice cooker for home use or business use.

The side view which notched some rice cookers of Embodiment 1 of this invention The principal part disassembled perspective view of the rice cooker of Embodiment 1 of this invention. (A) The figure which shows the temperature of the pot bottom (solid line) and the center part of cooking (dashed line) in a pre-cooking process when 1 rice is cooked with the rice cooker of Embodiment 1 of this invention (b) Embodiment of this invention The figure which shows the temperature of the pan bottom (solid line) in the pre-cooking process at the time of cooking 5 goseki with 1 rice cooker, and the temperature of a cooking center part (dashed line). The figure which shows the temperature of the pan bottom (solid line) in the pre-cooking process at the time of 1-cooking rice and the central part (broken line) of cooking (5) The figure which shows the temperature of the pot bottom (solid line) and the foodstuff center part (dashed line) in the pre-cooking process when doing

Explanation of symbols

10 Body
12 Pan 12b Installation surface 13 Induction heating coil (heating means)
19 Cooked food 20 Lid 30 Storage part 40 Weight detection means 41 Load cell (weight detection element)
42 Sensor stand (insulating material)
43 Batting cylinder (detector)
53 Lead wire 54 Connector 99 Clearance 424 Groove

Claims (1)

A main body having an open top surface, a pan that is detachably stored in a storage portion of the main body, a lid that covers the storage portion so as to be openable and closable, induction heating means that induction-heats the pan, and a direct connection to the storage portion Alternatively, a weight detection element that is indirectly attached, a sensor base that is directly attached to the weight detection element, and a detection body that is directly attached to the sensor base and abuts on a substantially central portion of the outer bottom of the pan. Weight detection means for detecting the total weight of the pan and the cooked food put in the pan by the weight detection element via the detection body, and the cooked food based on the output signal of the weight detection means A control unit that calculates the weight of the cooked food and controls the energization rate and / or the energization amount to the induction heating means according to the weight of the cooked food, and the detection body has a cylindrical shape, and the inside of the detection body Temperature detection to detect the temperature of the pan Comprising means, said temperature sensing means comprises a temperature sensing element, a lead wire is led out from the temperature sensing element, cooker said lead characterized in that it is fixed to the sensor base.

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