JP2725963B2 - Electric rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric rice cooker using induction heating as a heating means.

[0002]

2. Description of the Related Art Conventionally, a rice cooker has a heater for heating the bottom of a cooking pot and a temperature detecting means for sensing the temperature of the bottom of the pot by a pot bottom temperature sensor thermally connected to the bottom of the pot. By detecting that the water in the pot has disappeared due to boiling and the temperature at the bottom of the pot has risen to a predetermined temperature or higher, the end of rice cooking has been detected and heating has been stopped. In such a rice cooker, if a foreign substance such as rice is caught between the pot bottom temperature sensor and the pot, the temperature of the heater becomes higher than in a normal state because the heat received from the heater is not transmitted to the pot bottom. Before the temperature of the bottom of the pot rises at the end of the rice cooking, the temperature sensor becomes equal to or higher than the temperature at the end of the rice cooking, and a phenomenon of so-called premature cutting occurs. However, this abnormality will make the rice worse,
It did not happen that the body was damaged.

[0003]

However, in a rice cooker using induction heating as a heating means, an eddy current generated on the surface of the pot heats the pot surface to heat the cooked rice. If a foreign object such as rice is caught between the pan and the pot, the temperature will not be easily transmitted to the temperature sensor at the bottom of the pan, and even if the water in the pan is lost and the temperature at the bottom of the pan rises, the temperature will not exceed the predetermined temperature and heating will stop. It could not be done, and the temperature of the body storing the pot was abnormally high, and there was a risk of breakage.

Accordingly, the present invention is to provide a safety device in which even when foreign matter is caught between the bottom temperature sensor and the pot bottom, the body is not damaged by heat.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a cooking device main body, a bottomed cylindrical pot for storing an object to be cooked which is detachably provided in the cooking device main body, and induction heating the pot. An induction coil, a bottom temperature sensor for detecting the temperature of the bottom surface of the pan, a lid temperature sensor provided in a lid for covering the pan, and a temperature of the lid temperature sensor and a predetermined temperature (T1) are compared. Boiling detecting means for detecting that the food has boiled, and comparing the bottom temperature sensor at the time of boiling detection with a predetermined temperature (T2). If the bottom temperature sensor is low, there is a foreign substance in the bottom temperature sensor portion. The power control after the foreign matter determination is reduced from the normal power by the output of the foreign matter determination means.

[0006]

A bottom temperature sensor is provided in the main body of the cooker, a lid temperature sensor is provided in the lid body, the temperature of the steam generated from the inside of the pan is detected, and the temperature of the bottom of the pot at that time is compared with a predetermined temperature. A judging means for judging the presence of foreign matter is provided between the temperature sensor and the bottom of the pot, and the output of the judging means is used to reduce the subsequent electric power from the normal electric power to prevent an abnormal rise in temperature of the body. is there.

[0007]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 2 shows a structural diagram. (1) is a cooker main body, a synthetic resin frame (2), a metal outer frame (3), a synthetic resin bottom plate (4) provided below the outer frame, and the outer frame. (3) and a pan (5) made of a magnetic material (iron or stainless steel) provided so as to be housed inside the bottom plate (4). (6) (6) is an induction coil (hereinafter referred to as a coil) serving as an electric heating source in close contact with the lower surface of the bottom plate (4), (7) is a side heater mounted on the outer wall of the outer frame (3), (8) is a bottom temperature sensor that penetrates through the center of the bottom plate (4) and is in close contact with the bottom of the pan; (9) is a coil mount supporting the coil (6); and (10) is provided on the lower surface of the coil mount. A ferrite for shielding, (11) is a power supply board disposed in a space (12) below the bottom wall of the frame (2) and the ferrite (10), and includes a choke coil (1).
3) and a heat sink (14) are attached. (15) is a fan for cooling the radiator plate, (16) is a control board arranged in a space (17) between the side wall of the frame (2) and the outer frame (3), and (18) is a frame for the frame (2). It is a frame cover for fixing the upper portion of each of the outer frames (3).

A lid (19) is pivotally supported on one side to the cooker main body (1), and the other side is freely engageable with the cooker main body. The lid has an upper plate (20) and a lower plate (21). It is composed of a metal radiator plate (22) and an inner lid (23) provided below the radiator plate. (24) is a lid heater mounted on the upper surface of the heat sink (22), and (25) is a lid heater (21) and the heat sink (2).
2) A lid temperature sensor arranged between the two. (26) an outer packing fitted and fixed to the outer peripheral edge of the heat sink (22);
(27) is an inner packing fitted and fixed to the outer peripheral edge of the inner lid (23), and (28) is the upper plate (20) and the heat sink (2).
2) a steam hole which is opened to communicate with the outside air; (29) is a pressure regulating device provided at the center of the inner lid (23), and is a hollow having a plurality of pressure relief holes (30) at the bottom. A valve seat (3) having a pressure hole (32) provided in a lower portion of the valve housing (31).
3) and the pressure hole (3
2) and a pressure regulating valve (34) for closing. Although not shown in detail, the microcomputer (M) described later has a temperature detected by the lid temperature sensor (25) and a predetermined temperature (T1 in FIG. 3).
And a boiling detecting means for detecting that the food is boiling.

FIG. 1 shows a block diagram.
(M) is a microcomputer in which a predetermined rice cooking operation is programmed in advance, and a bottom temperature sensor (8) and a lid temperature sensor (2).
Foreign matter is interposed between the input circuit (11) of 5), the signal input circuit (12) of the external input device (L) for switching between rice cooking / heating and a rice cooking start signal, etc., and the pan bottom and the bottom temperature sensor. Foreign matter determining means (H) for detecting an abnormal state in the case;
A RAM (J), R0M (K), and an output control circuit (O) are provided.

The foreign matter judging means (H) compares the temperature of the bottom temperature sensor (8) with the temperature of the lid temperature sensor (25) when foreign matter is sandwiched between the bottom of the pot and the bottom temperature sensor. (8) is lower than the lid temperature sensor (25),
When the temperature difference is equal to or more than a certain value, it is determined that the state is abnormal.

Next, the rice cooking operation in a normal state will be described. FIG. 3 shows a characteristic diagram of the pot bottom center temperature, the bottom temperature sensor temperature, and the lid temperature sensor temperature during the rice cooking operation under normal conditions.

When rice cooking is started in (a) of FIG. 3, a current having a frequency of 25 kHz to 40 kHz is applied to the coils (6) and (6) by the output of the microcomputer (M), and an eddy current is generated to generate the pot (5). Is heated by the rated induction power (100%) of the coils (6) and (6). At the same time, the lid heater (24) is also energized to heat the radiator plate (22) and the inner lid (23). The heat sink (2
2) and the space between the inner lid (23) and the lid temperature sensor (2
The temperature of 5) also increases.

When the cooked rice starts to boil, the temperature in the pot (5) rises, the pressure in the pot increases, and the pressure regulating valve (34) is pushed up by the steam pressure, and the steam passes through the pressure hole (32). Through the steam vent (28) to the outside air. The steam at this time is applied to the steam holes (2) of the radiator plate (22).
8) The surroundings are heated, and the temperature of the lid temperature sensor (25) rapidly rises due to the temperature rise.

In (b), when the temperature of the lid temperature sensor (25) reaches the predetermined temperature (T1), the boiling detecting means interrupts the current flowing through the coil (6) to make the induction heating power smaller than the rated induction power. The process moves to the boiling step of maintaining the boiling state by setting the temperature to a low level (W1).

Thereafter, when the water in the pot (5) disappears in (c) and the temperature rises rapidly and the temperature of the bottom temperature sensor reaches (T3 ≒ 130 degrees) in (d), the microcomputer inputs the change. Then, the power supply to the coils (6) and (6) is stopped to start the spotting process. After a lapse of a predetermined time (e) after entering the spotting process, the coil is again energized with the power of (W1) to perform additional cooking. Eventually, when the pot temperature decreases to the predetermined temperature in (f), the process proceeds to the heat retaining step.

Next, the operation in the case where foreign matter is caught between the bottom of the pot and the bottom temperature sensor will be described with reference to FIG. FIG.
Shows characteristic diagrams of the pan bottom center temperature, the bottom temperature sensor temperature, and the lid temperature sensor temperature during the rice cooking operation at the time of abnormality.

When boiling starts and the temperature of the lid temperature sensor (25) reaches the predetermined temperature (T1), the temperature of the bottom temperature sensor is lower than the predetermined temperature (T2). It is determined that there is some abnormality in the temperature detection performance of the bottom temperature sensor (8). Since the temperature of the lid rises due to the steam temperature, the temperature of the lid temperature sensor does not normally become higher than the temperature of the bottom temperature sensor, so (T2) is set slightly lower than (T1).

The microcomputer changes the subsequent control according to the result of the determination as follows. First, the power after the boiling detection is set to a predetermined power (W2) lower than the normal power, and the energization of the lid heater (24) is stopped. . When the water in the pot (5) disappears and the temperature rises rapidly and the temperature of the bottom temperature sensor (8) reaches a temperature lower than the above (T3) (T4 ≒ 105 degrees), the power supply to the coil (6) is stopped. Enter the spotting process. The temperature (T4) is set lower than the normal rice-cooking end determination temperature (T3). In addition, no additional cooking is performed during the steaming process.

[0019]

As described above, the present invention detects an abnormality in the thermal performance of the bottom temperature sensor by comparing the temperatures of the lid temperature sensor and the bottom temperature sensor when the food reaches the boiling point. It is possible to realize a safe rice cooker without any danger of damage to the body because the power supply thereafter can be limited. In addition, even in an abnormal state, the rice cooking process is performed to the end, so that the rice is cooked and does not become cooked rice. Further, since the time when the food is boiled is used as a reference, the detected temperature of the food is accurate (about 100 degrees), and there is no erroneous determination that the foreign matter is on the bottom temperature sensor.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electric rice cooker according to the present invention.

FIG. 2 is a partial sectional view of the electric rice cooker.

FIG. 3 is a rice cooking characteristic diagram of the electric rice cooker in a normal state.

FIG. 4 is a characteristic diagram of rice cooking when the rice cooker is abnormal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cooker main body 5 Pot 6 Induction heating coil 8 Bottom temperature sensor 19 Lid 25 Lid temperature sensor H Foreign substance determination means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Norio Yamane 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (56) Reference: 1-178825 (JP, U)

Claims (1)

(57) [Claims] And 1. A cooker body, a bottomed cylindrical pot for accommodating the foods provided in the detachably to the cooking device body, an induction coil for induction heating the該鍋, before Kinabe of a bottom temperature sensor for detecting the temperature of the bottom surface, and a lid temperature sensor provided in front Kinabe the lid body to applying a cover temperature and the predetermined temperature of the lid temperature sensor
(T1) to detect that the food has boiled
Means for detecting boiling, a bottom temperature sensor for detecting boiling, and a predetermined temperature.
If the bottom temperature sensor is lower than the temperature (T2), the bottom temperature
Foreign matter determining means for determining that there is foreign matter in the degree sensor
A rice cooker, wherein the power control after the foreign matter determination is reduced from the power in a normal state by the output of the foreign matter determination means .