Split type electromagnetic kettle capable of accurately controlling temperature

Abstract

The utility model relates to the field of electric kettles, in particular to a split type electromagnetic kettle capable of accurately controlling temperature, which comprises a base and a kettle body placed on the base, and the base comprises a power supply circuit, a control circuit, a vibration sensor, an electromagnetic coil, a kettle bottom NTC (Negative Temperature Coefficient), an infrared temperature measuring sensor and a hot plate NTC; the electromagnetic coil is fixedly arranged on the top face of the base. The bottom face of the kettle body abuts against the electromagnetic coil. The infrared temperature measuring sensor right faces the bottom of the kettle body, the kettle bottom NTC abuts against the bottom face of the kettle body, the hot plate NTC is fixedly connected with the outer surface of the electromagnetic coil, and the vibration sensor abuts against the bottom face of the kettle body. The vibration sensor, the kettle bottom NTC, the infrared temperature measurement sensor and the hot plate NTC are used for detecting the vibration value and the bottom surface temperature of the kettle body of the kettle and the surface temperature of the electromagnetic coil respectively, four sensor parameters are provided for the control circuit, and therefore a basis is provided for controlling the water boiling process more accurately.

Description

Technical Field

[0001] The utility model relates to the field of electric kettles, in particular to a split electromagnetic kettle with precise temperature control. Background Art

[0002] As the most common type of electric kettle, split electric kettles are mainly classified into two categories. One category is that there is only a power supply interface on the base, and the electromagnetic coil and the electronic control components are integrated in the kettle body. Due to the need for the aesthetic and lightweight design of the kettle body, such as a glass kettle body or a ceramic kettle body, it is difficult to integrate the electromagnetic coil and the electronic control components inside. Therefore, the heating and electronic control functions need to be integrated in the base, similar to a small electric ceramic stove or induction cooker, and the kettle body is heated by the base to boil water.

[0003] However, for an electric kettle that uses the base to integrate the heating and electronic control functions to heat the kettle body, how to accurately measure the water temperature inside the kettle has become a difficult problem. The existing solutions generally use temperature sensors such as thermistors near the electromagnetic coil of the base to indirectly judge the boiling process of the water, so as to turn off the heating circuit after the water boils.

[0004] However, there are many limitations in using only a temperature sensor to measure the temperature. For example, the thermistor is set around the electromagnetic coil of the base, and it can only directly measure the temperature of the electromagnetic coil or the bottom of the kettle body, and cannot directly measure the water temperature inside the kettle, resulting in a certain lag. Affected by the thermal conductivity of the kettle body and different water levels, there is a large difference between the water temperature inside and the temperature actually measured by the sensor, and it is very easy to have problems with inaccurate water temperature prediction. Often, the water will continue to be heated for a period of time after boiling, resulting in the water boiling over the kettle body, or the water is not fully heated and boiled, and the base has automatically stopped heating due to overheating. Moreover, when the electric kettle is used at different altitudes (different atmospheric pressure environments), the temperature measured by the temperature sensor is difficult to directly adjust the temperature threshold with the change of the boiling point of the water, making it difficult for the electric kettle product to be directly applicable and promoted in high-altitude areas. Summary of the Utility Model

[0005] In order to overcome the problems of inaccurate measurement of the water body temperature of the existing electric kettle, difficult precise judgment of the boiling point, and inability to adapt to different boiling points at different altitudes, the utility model provides a split electromagnetic kettle with precise temperature control.

[0006] The technical solution adopted by the present utility model is as follows: A split electromagnetic kettle with precise temperature control, comprising a base and a kettle body placed on the base. The base includes a power supply circuit, a control circuit, a vibration sensor, an electromagnetic coil, a bottom NTC of the kettle, an infrared temperature sensor, and a hot plate NTC. The electromagnetic coil is fixedly arranged on the top surface of the base, and the bottom surface of the kettle body abuts against the electromagnetic coil. The infrared temperature sensor faces the bottom of the kettle body, the bottom NTC of the kettle abuts against the bottom surface of the kettle body, the hot plate NTC is fixedly connected to the outer surface of the electromagnetic coil, and the vibration sensor abuts against the bottom surface of the kettle body. The power supply circuit is used to connect to an external power supply, and the control circuit is used to control the start and stop of the electromagnetic coil and the magnitude of the output power according to the signals output by the bottom NTC of the kettle, the infrared temperature sensor, and the hot plate NTC. The power supply circuit, the electromagnetic coil, the bottom NTC of the kettle, the infrared temperature sensor, and the hot plate NTC are all electrically connected to the control circuit respectively.

[0007] Preferably, a microcrystalline panel is provided on the upper surface of the base. The lower surface of the microcrystalline panel abuts against the upper surface of the electromagnetic coil. A heat insulation ring is provided around the microcrystalline panel. The infrared temperature sensor faces the microcrystalline panel, and the bottom NTC of the kettle abuts against the bottom surface of the microcrystalline panel.

[0008] Preferably, a control knob is provided on one side of the base. The control knob is electrically connected to the control circuit.

[0009] Preferably, an infrared through hole is provided in the middle of the electromagnetic coil in the vertical direction, and the infrared temperature sensor is arranged in the infrared through hole.

[0010] Preferably, a heat insulation layer is provided on the inner wall of the infrared through hole.

[0011] Preferably, a housing is provided on the outside of the base. The front surface of the vibration sensor is fixedly connected to the inner side wall of the housing.

[0012] Preferably, a bottom plate is provided at the lower part of the housing. The bottom plate is fixedly connected to the housing by screws.

[0013] Preferably, a hot plate bracket is fixedly provided on the bottom plate, and the electromagnetic coil is fixedly connected to the hot plate bracket.

[0014] Preferably, a cooling fan is fixedly provided in the base, and the air outlet direction of the cooling fan faces the position of the electromagnetic coil.

[0015] Preferably, a plurality of shock-absorbing foot pads are provided on the bottom surface of the base, and sound insulation cotton and a metal protective cover are provided on the back and side surfaces of the vibration sensor.

[0016] The beneficial effects of the present utility model are:

[0017] Through four sensors, namely a vibration sensor, an NTC at the bottom of the kettle, an infrared temperature sensor, and an NTC of the hot plate, the vibration value of the kettle body, the bottom surface temperature, and the surface temperature of the electromagnetic coil of the kettle are detected respectively, providing four sensor parameters for the control circuit, thereby providing a basis for more precise control of the boiling water process. Brief Description of the Drawings

[0018] The present utility model will be further described below in conjunction with the accompanying drawings of the specification, where:

[0019] Figure 1 is a schematic structural diagram of the first embodiment of the present utility model;

[0020] Figure 2 is an exploded view of the components of the second embodiment of the present utility model;

[0021] Figure 3 is a sensor parameter - time curve of the second embodiment of the present utility model.

[0022] In the figure: 1, kettle body; 2, base; 201, bottom plate; 202, housing; 203, heat insulation ring; 3, control circuit; 301, control knob; 4, vibration sensor; 5, NTC at the bottom of the kettle; 6, infrared temperature sensor; 601, infrared through - hole; 7, NTC of the hot plate; 8, electromagnetic coil; 801, microcrystalline panel; 9, hot plate bracket; 10, cooling fan; 11, power supply circuit. Detailed Embodiment

[0023] The technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0024] See Figure 1, which is the first embodiment of the present utility model. This embodiment specifically discloses a split electromagnetic kettle with precise temperature control, including a base 2 and a kettle body 1 placed on the base 2. The base 2 includes a power supply circuit 11, a control circuit 3, a vibration sensor 4, an electromagnetic coil 8, a bottom NTC 5 of the kettle, an infrared temperature sensor 6, and a hot plate NTC 7. The electromagnetic coil 8 is fixedly arranged on the top surface of the base 2, and the bottom surface of the kettle body 1 abuts against the electromagnetic coil 8. The infrared temperature sensor 6 faces the bottom of the kettle body 1, the bottom NTC 5 abuts against the bottom surface of the kettle body 1, the hot plate NTC 7 is fixedly connected to the outer surface of the electromagnetic coil 8, and the vibration sensor 4 abuts against the bottom surface of the kettle body 1. The power supply circuit 11 is used to connect to an external power supply and supply power to the control circuit 3 and the electromagnetic coil 8. The external power supply can be mains power supply or battery / power supply. The control circuit 3 is used to control the start and stop of the electromagnetic coil 8 and the magnitude of the output power according to the signals output by the bottom NTC 5 of the kettle, the infrared temperature sensor 6, and the hot plate NTC 7. The power supply circuit 11, the electromagnetic coil 8, the bottom NTC 5 of the kettle, the infrared temperature sensor 6, and the hot plate NTC 7 are respectively electrically connected to the control circuit 3.

[0025] The kettle body 1 and the base 2 adopt a separable design, and the bottom surface of the kettle body 1 is placed above the upper surface of the heating assembly.

[0026] By using multiple temperature sensors of different types and different installation positions to corroborate each other, on the one hand, the measured value of the temperature is made more accurate, and on the other hand, it can be detected whether there is a problem with the heat conduction between the heating assembly and the bottom of the kettle body 1. For example, if the temperature changes sharply and the temperature difference between the heating assembly and the bottom of the kettle body 1 is too large, it indicates that there is a problem with the heat conduction between the bottom of the kettle body 1 and the heating assembly, or when the kettle body 1 is picked up, the heating is immediately stopped to prevent the heating assembly from being burned out.

[0027] The vibration sensor 4 is a piezoelectric ceramic buzzer, and a signal amplification circuit is provided on one side of the buzzer. The signal amplification circuit is electrically connected to the control circuit 3.

[0028] In this embodiment, through four sensors, namely the vibration sensor 4, the bottom NTC 5 of the kettle, the infrared temperature sensor 6, and the hot plate NTC 7, the vibration value of the kettle body 1 of the kettle, the bottom temperature, and the surface temperature of the electromagnetic coil 8 are respectively detected, providing four sensor parameters for the control circuit 3, thereby providing a basis for more precise control of the boiling water process.

[0029] See Figure 2 and Figure 3 , in order to illustrate how the four sensors work together to make the temperature control of the boiling water process more precise, the following is the second embodiment of this solution, which is a more specific embodiment of the first embodiment.

[0030] First, the bottom NTC5 of the kettle, the infrared temperature sensor 6, and the hot plate NTC7 are all temperature sensors. Among them, the bottom NTC5 of the kettle and the hot plate NTC7 are thermistors with the same model. The infrared temperature sensor 6 is a device that uses infrared rays to measure temperature. The temperature measurement principle is the blackbody radiation law, and it measures the temperature at the bottom of the kettle body 1 by facing the bottom surface of the kettle body 1. The working principles of the three temperature sensors are as follows:

[0031] S1. The control circuit 3 obtains the temperature value T2 through the bottom NTC5 of the kettle, obtains the temperature value T3 through the infrared temperature sensor 6, and obtains the temperature value T4 through the hot plate NTC7;

[0032] S2. Take the average value of the current temperature value T2 and the temperature value T3 as the temperature value T1 of the kettle body 1 at the current moment;

[0033] S3. When it is detected that the difference between the temperature value T4 and the temperature value T1 is greater than 10°C, the control circuit 3 issues an alarm signal and cuts off the power supply to the electromagnetic coil 8.

[0034] The temperature value T1 of the kettle body 1 is used as an approximation of the water temperature in the kettle body 1. Usually, there is a large deviation from the actual temperature. Therefore, this solution introduces a vibration sensor 4 to assist in judging the boiling water process, so as to more accurately identify the boiling water process and determine the time when the water boils during the boiling water process.

[0035] See Figure 3 , the specific working principle of this embodiment is realized based on the curve characteristics of the underwater sound changing with temperature, as follows:

[0036] First, during the process of heating water until it boils, the convection at the bottom of the water body will gradually increase to a peak and then gradually decrease after being heated. Especially in a kettle, strong convection of the water body will generate noise, and the intensity of this noise is proportional to the intensity of the convection;

[0037] Second, during the heating process of water, bubbles are generated due to the vaporization of the water vapor in contact with the heating surface at the bottom. When the bubbles rise to the water surface and burst, they will generate vibrations, thereby emitting a certain regular sound wave. The frequency, intensity of this sound wave are related to the water temperature and the heating power.

[0038] The two work together to make the noise peak during the water body heating process appear at about 75°C, and the temperature range with a relatively large noise loudness is roughly 60°C - 90°C. This value is related to the performance of the sensor and the local atmospheric pressure. For the specific measured waveform, see Figure 3(The horizontal axis is time, in seconds, and the vertical axis is the reading of the vibration sensor 4 and the reading of the temperature sensor T1, respectively), that is, the curve characteristics of the water sound changing with the temperature during the boiling process. Moreover, even if the peak value is affected by the air pressure change in the environment where the kettle is used, the temperature fluctuates. Therefore, the vibration intensity (noise loudness) of the water body during the boiling process can be detected by the vibration sensor 4 to judge the heating process of the water body.

[0039] However, the existing water-boiling equipment generally uses the vibration sensor 4 alone or the temperature sensor alone to judge the heating process of the water body, and both have some unavoidable disadvantages, such as the hysteresis of temperature measurement, interference by external vibration, boiling point change caused by air pressure change, and sensor sensitivity attenuation, etc. Therefore, this embodiment uses the vibration sensor 4 and the temperature sensor to monitor the water-boiling process of the electric kettle at the same time, so as to more accurately judge the boiling point, and avoid the problem that the heating cannot be turned off on time or turned off in advance due to inaccurate water temperature measurement, thereby causing the water to not be completely boiled or over-boiled.

[0040] The upper surface of the base 2 of this embodiment is provided with a microcrystalline panel 801, the lower surface of the microcrystalline panel 801 is in contact with the upper surface of the electromagnetic coil 8, the microcrystalline panel 801 is provided with a heat insulation ring 203 around it, the infrared temperature sensor 6 is directly facing the microcrystalline panel 801, and the pot bottom NTC5 is in contact with the bottom surface of the microcrystalline panel 801. The material used for the microcrystalline panel 801 is glass-ceramic (gl ass-ceramic), also known as microcrystalline glass and microcrystalline ceramic. The microcrystalline panel 801 is close to the bottom surface of the kettle body 1. On the one hand, it isolates the kettle body 1 from the electromagnetic coil 8, protects the electromagnetic coil 8 from direct heat and water vapor erosion, and at the same time plays a role in beauty and easy cleaning. The temperature sensor indirectly obtains the temperature value of the bottom of the kettle body 1 by measuring the temperature of the microcrystalline panel 801.

[0041] A control knob 301 is provided on one side of the base 2, and the control knob 301 is electrically connected to the control circuit 3. It is used to manually control the water boiling process, such as manually inputting a timing time, setting a temperature, and manually starting or ending water boiling.

[0042] An infrared through hole 601 is provided in the middle of the electromagnetic coil 8 along the vertical direction, and the infrared temperature sensor 6 is arranged in the infrared through hole 601; the inner wall of the infrared through hole 601 is provided with a heat insulation layer, which is used to isolate the interference of the surrounding temperature on the infrared temperature sensor 6 as much as possible, so that the measured temperature value is closer to the temperature at the bottom of the kettle body 1.

[0043] Preferably, a housing 202 is provided on the outer side of the base 2 of this embodiment, and the front surface of the vibration sensor 4 is fixedly connected to the inner side wall of the housing 202. A bottom plate 201 is provided at the lower part of the housing 202, and the bottom plate 201 is fixedly connected to the housing 202 by screws. The housing 202 protects the internal circuit and the electromagnetic coil 8 and makes the appearance more beautiful.

[0044] The control circuit 3 filters and performs analog-to-digital conversion on the buzzer signal amplified by the signal amplification circuit through a low-pass filtering algorithm to obtain a vibration value Z1. The buzzer is provided on one side of the bottom of the kettle body 1, and the front surface of the buzzer is closely attached to the inner side of the housing 202 to better obtain the vibration value transmitted from the kettle body 1.

[0045] A plurality of shock-absorbing foot pads are provided on the bottom surface of the base 2 of this embodiment, and sound insulation cotton and a metal protective cover are provided on the back and side surfaces of the vibration sensor 4. It is used to reduce external noise, the electromagnetic buzzing sound when the electromagnetic coil 8 works, and the interference of external vibration and electromagnetic waves on the reading of the vibration sensor 4.

[0046] A hot plate bracket 9 is fixedly provided on the bottom plate 201, and the electromagnetic coil 8 is fixedly connected to the hot plate bracket 9. By fixing the electromagnetic coil 8 from below through the hot plate bracket 9, the contact between the electromagnetic coil 8 and the housing 202 and the microcrystalline panel 801 can be reduced, and the heat directly transmitted to the electromagnetic coil 8 can be reduced. A plurality of heat insulation columns can also be provided on the hot plate bracket 9 for connecting and fixing the electromagnetic coil 8, further reducing the heat transfer, increasing the service life of the hot plate bracket 9, and reducing the heat resistance requirement of the material.

[0047] Preferably, a cooling fan 10 is fixedly provided in the base 2 of this embodiment. The cooling fan 10 is fixed in the hot plate bracket 9, and the air outlet direction of the cooling fan 10 faces the position of the electromagnetic coil 8 for actively dissipating heat from the electromagnetic coil 8. Correspondingly, air inlets and air outlets should be provided at corresponding positions of the housing 202, which is a conventional design in the art.

[0048] The electromagnetic coil 8 of this embodiment generates an induced current in the conductor at the bottom of the kettle body 1 through a magnetic field change to generate heat. In other embodiments, the electromagnetic coil 8 can also be replaced with a wire coil wound by an electric heating wire, which directly generates heat after being powered on to heat the bottom of the kettle body 1.

[0049] According to Figure 3 , the specific method for the control circuit 3 of this embodiment to control the boiling water process is as follows:

[0050] A1. In response to the boiling water instruction, heat the kettle body 1, and start measuring the temperature value T1 and the vibration value Z1 of the kettle body 1 synchronously or after a second preset time;

[0051] A2. Detect in real time whether the temperature value T1 is greater than or equal to the boiling point record value. If so, stop heating the kettle body 1; otherwise, determine whether the temperature value T1 and the vibration value Z1 meet Condition 1. If so, after delaying for the first preset time since the moment when Condition 1 is first met, use the corresponding temperature value T1 as the new boiling point record value. After obtaining the new boiling point record value, stop heating the kettle body 1; otherwise, repeat this step.

[0052] Among them, both the first preset time and the second preset time are preset time values; the boiling point record value represents the water boiling point temperature value recorded in the last water boiling of the kettle body 1, and the boiling point record value before the kettle body 1 first heats and boils water is the initial preset value.

[0053] Condition 1 is specifically: the first temperature value < temperature value a < temperature value b, and at the same time, the second temperature value < temperature value T1.

[0054] Among them, the first temperature value is the minimum temperature value preset during the boiling process where the water sound is necessarily greater than the vibration lower limit threshold, and the second temperature value is a preset fixed temperature value; the temperature value a represents the temperature value T1 at the same moment when the maximum vibration value appears; the maximum vibration value represents the maximum value among all the vibration values Z1 up to the current time; the temperature value b represents the temperature value T1 at the same moment when the vibration value Z1 is first less than the vibration lower limit threshold after the maximum vibration value appears; the vibration lower limit threshold is a preset vibration value.

[0055] Specifically, the first preset time is 30 seconds, the second preset time is 5 seconds, the initial value of the boiling point record value is 100 °C, the minimum vibration threshold is 200, and the temperature judgment threshold is 70 °C.

[0056] In this embodiment, the readings of the temperature sensor and the vibration sensor 4 are mutually verified to determine whether the water in the kettle is about to boil, and the temperature value of the boiling point and the vibration value judgment conditions are updated through mutual verification, making the boiling point judgment of the kettle more accurate and automatically adapting to the boiling points at different altitudes.

[0057] Specifically, by detecting whether the vibration value Z1 first rises to the maximum value and then falls back to less than the minimum vibration threshold according to the Figure 3 pattern, it is used to assist in judging whether the boiling process is approaching boiling, so as to judge that the water has boiled sufficiently after delaying for the first preset time, and avoid the boiling point temperature change caused by inaccurate measurement of the temperature sensor and altitude (atmospheric pressure) change.

[0058] In the above specific embodiments, the object, technical solution and beneficial effects of the present utility model have been further described in detail. It should be understood that the above are only specific embodiments of the present utility model and are not used to limit the protection scope of the present utility model. It is particularly pointed out that for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A split electromagnetic kettle with precise temperature control, comprising a base (2) and a kettle body (1) placed on the base (2), characterized in that: The base (2) comprises a power supply circuit (11), a control circuit (3), a vibration sensor (4), an electromagnetic coil (8), a pot bottom NTC (5), an infrared temperature sensor and a hot plate NTC (7); The electromagnetic coil (8) is fixedly arranged on the top surface of the base (2), and the bottom surface of the kettle body (1) is in contact with the electromagnetic coil (8); The infrared temperature sensor faces the bottom of the kettle body (1), the kettle bottom NTC (5) abuts against the bottom surface of the kettle body (1), the hot plate NTC (7) is fixedly connected to the outer surface of the electromagnetic coil (8), and the vibration sensor (4) abuts against the bottom surface of the kettle body (1); The power supply circuit (11) is used to connect to an external power supply. The control circuit (3) is used to control the start and stop of the electromagnetic coil (8) and the magnitude of the output power according to the signals output by the NTC at the bottom of the kettle (5), the infrared temperature sensor and the hot plate NTC (7). The power supply circuit (11), the electromagnetic coil (8), the NTC at the bottom of the kettle (5), the infrared temperature sensor and the hot plate NTC (7) are all electrically connected to the control circuit (3) respectively.

2. A split electromagnetic kettle with precise temperature control according to claim 1, characterized in that: A microcrystalline panel (801) is provided on the upper surface of the base (2); the lower surface of the microcrystalline panel (801) is in contact with the upper surface of the electromagnetic coil (8); a heat insulation ring (203) is provided around the microcrystalline panel (801); the infrared temperature sensor faces the microcrystalline panel (801); and the NTC (5) at the bottom of the pot is in contact with the bottom surface of the microcrystalline panel (801).

3. The split-type electromagnetic kettle with precise temperature control according to claim 1, characterized in that: A control knob (301) is provided on one side of the base (2), and the control knob (301) is electrically connected to the control circuit (3).

4. The split-type electromagnetic kettle with precise temperature control according to claim 1, characterized in that: An infrared through hole (601) is provided in the middle of the electromagnetic coil (8) along the vertical direction, and the infrared temperature measuring sensor is arranged in the infrared through hole (601).

5. The split-type electromagnetic kettle with precise temperature control according to claim 4, characterized in that: The inner wall of the infrared through hole (601) is provided with a heat insulation layer.

6. The split-type electromagnetic kettle with precise temperature control according to claim 1, characterized in that: A shell (202) is provided on the outer side of the base (2), and the front side of the vibration sensor (4) is fixedly connected to the inner side wall of the shell (202).

7. A split-type electromagnetic kettle with precise temperature control according to claim 6, characterized in that: A bottom plate (201) is provided at the lower part of the shell (202), and the bottom plate (201) is fixedly connected to the shell (202) by screws.

8. The split-type electromagnetic kettle with precise temperature control according to claim 7, characterized in that: A hot plate bracket (9) is fixedly provided on the bottom plate (201), and the electromagnetic coil (8) is fixedly connected to the hot plate bracket (9).

9. The split-type electromagnetic kettle with precise temperature control according to claim 1, characterized in that: A cooling fan (10) is fixedly arranged inside the base (2), and the air outlet direction of the cooling fan (10) is toward the position of the electromagnetic coil (8).

10. The split-type electromagnetic kettle with precise temperature control according to claim 1, characterized in that: The bottom surface of the base (2) is provided with a plurality of shock-absorbing foot pads, and the back and sides of the vibration sensor (4) are provided with sound insulation cotton and a metal protective cover.

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