Liquid heater

Abstract

To provide a liquid heater capable of completing heating of liquid while suppressing deviation from a set temperature regardless of amount of liquid.SOLUTION: A liquid heater 100 comprises: a liquid container 320; a heating unit 341 heating liquid in the liquid container; a temperature measurement unit BS measuring liquid temperature; a temperature setting unit 403 for setting set temperature; and a control unit CO controlling the heating unit based on measured temperature measured by the temperature measurement unit. The control unit can perform control in such a manner that: the energization of the heating unit is stopped when determining that measured temperature reaches first threshold temperature lower than set temperature; the heating unit is not energized when determining that measured temperature reaches second threshold temperature higher than the first threshold temperature and lower than set temperature after the energization of the heating unit is stopped; and the heating unit is not energized after the heating unit is energized when determining that measured temperature does not reach the second threshold temperature.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a liquid heater. [Background technology]

[0002] For example, as shown in Patent Document 1 (JP 2020-048721 A) below, a liquid heater is proposed that includes "a liquid container, a heating unit that heats the liquid stored inside the liquid container, a temperature measuring unit that measures the temperature of the liquid, a temperature setting unit that sets the set temperature, and a control unit that controls the heating unit based on the measured temperature measured by the temperature measuring unit." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-048721 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional liquid heaters described above, since heating is completed when the measured temperature reaches the set temperature, there are cases where, for example, when the amount of liquid is small, the actual temperature of the liquid when heating is completed significantly exceeds the set temperature (overshoots) due to residual heat in the heating section, etc. As a result, the temperature of the liquid when heating is completed varies greatly from the set temperature depending on the amount of liquid, etc.

[0005] An object of the present invention is to provide a liquid heater that can complete heating of a liquid while suppressing deviation from a set temperature regardless of the amount of liquid, etc. [Means for solving the problem]

[0006] The liquid heater according to the present invention comprises: A liquid container; a heating unit that heats the liquid stored inside the liquid container; a temperature measuring unit for measuring the temperature of the liquid; a temperature setting unit for setting a set temperature; a control unit that controls the heating unit based on the temperature measured by the temperature measuring unit, When the control unit determines that the measured temperature has reached a first threshold temperature that is lower than the set temperature, it stops supplying power to the heating unit, and after stopping supplying power to the heating unit, it determines whether the measured temperature has reached a second threshold temperature that is higher than the first threshold temperature and lower than the set temperature, and if it determines that the measured temperature has reached the second threshold temperature, it does not supply power to the heating unit, and if it determines that the measured temperature has not reached the second threshold temperature, it does not supply power to the heating unit after supplying power to the heating unit.

[0007] According to the above configuration, for example, when the amount of liquid is large, the temperature rise due to residual heat from the heating unit is smaller than when the amount of liquid is small. Therefore, if the measured temperature of the liquid does not reach the second threshold temperature after power supply to the heating unit is stopped, additional heating is performed, and the liquid temperature at the completion of heating approaches the set temperature. On the other hand, for example, when the amount of liquid is small, the temperature rise due to residual heat from the heating unit is larger than when the amount of liquid is large. Therefore, if the measured temperature of the liquid reaches the second threshold temperature after power supply to the heating unit is stopped, heating can be completed with less heating than when the amount of liquid is large (heating is completed at a lower temperature than when the amount of liquid is large), suppressing overshoot and allowing the temperature to approach the set temperature. In this way, heating appropriate to the amount of liquid, etc., is performed, and the heating of the liquid can be completed with reduced deviation from the set temperature regardless of the amount of liquid, etc.

[0008] In the present invention, When measuring the temperature after the control unit stops energizing the heating unit, it is preferable that the temperature measurement unit measures the temperature after a standby time has elapsed.

[0009] Immediately after power supply to the heating unit is stopped, thermal convection may prevent accurate measurement of the measured temperature. With the above configuration, the measured temperature is measured after the standby time has elapsed since power supply to the heating unit was stopped. Therefore, with this liquid heater, the measured temperature can be measured as accurately as possible after power supply to the heating unit is stopped.

[0010] In the present invention, The control unit When it is determined that the measured temperature has reached the first threshold temperature, It is determined whether the set temperature is equal to or higher than a reference temperature, and if it is determined that the set temperature is equal to or higher than the reference temperature, ,before When it is determined that the set temperature is lower than the reference temperature by not energizing the heating unit, ,before Stop powering the heating section. and then determining whether the measured temperature has reached the second threshold temperature, and if it is determined that the measured temperature has reached the second threshold temperature, not energizing the heating unit, and if it is determined that the measured temperature has not reached the second threshold temperature, energizing the heating unit and then not energizing the heating unit. This is preferable.

[0011] According to the above configuration, the control unit takes into consideration that as the set temperature increases, the gap between the set temperature and room temperature becomes larger, making the liquid temperature more likely to drop, and can complete heating of the liquid while minimizing deviation from the set temperature regardless of the amount of liquid, etc.

[0012] In the present invention, The temperature setting unit is capable of selecting the set temperature from a plurality of set temperatures, and it is preferable that, for the plurality of set temperatures equal to or higher than the reference temperature, the difference between the set temperature and the first threshold temperature becomes smaller as the set temperature becomes higher.

[0013] According to the above configuration, as the set temperature increases, the gap with room temperature becomes larger and the temperature of the liquid becomes more likely to drop, so a first threshold temperature is set that is suitable for bringing the temperature of the liquid at the completion of heating close to the set temperature, depending on the set temperature selected.

[0014] In the present invention, The temperature setting unit is capable of selecting the set temperature from a plurality of set temperatures, and it is preferable that, for the plurality of set temperatures that are less than a reference temperature, the difference between the set temperature and the second threshold temperature becomes smaller as the set temperature becomes higher.

[0015] In the present invention, The temperature setting unit is capable of selecting the set temperature from a plurality of set temperatures, and for the plurality of set temperatures, the set temperature becomes higher as the set temperature becomes higher. First Threshold Temperature It is preferable that the difference between

[0016] According to the above configuration, the control unit can be made to flexibly control the heating unit in accordance with the selected set temperature.

[0017] In the present invention, It is preferable that the temperature setting unit can select the set temperature from a plurality of sets of set temperatures, and that, for the plurality of set temperatures, the difference between the set temperature and the second threshold temperature becomes smaller as the set temperature becomes higher. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of an electric kettle according to an embodiment of the present invention; [Figure 2] 1 is a plan view of an electric kettle according to an embodiment of the present invention. [Figure 3] 3 is a cross-sectional view taken along the line AA in FIG. 2. [Figure 4] This is a cross-sectional view taken along the line BB in Figure 2. In this figure, the lid unit portion is shown enlarged. [Figure 5] FIG. 4 is an enlarged view of the lid unit portion shown in FIG. 3. [Figure 6] 1 is a control block diagram of an electric kettle according to an embodiment of the present invention. [Figure 7] FIG. 4 is a conceptual diagram showing a temperature control table according to an embodiment of the present invention. [Figure 8] 4 is a flowchart showing a processing flow in a control device of an electric kettle according to an embodiment of the present invention. [Figure 9] 1 is a diagram showing the on / off control of the print heater and the temperature transition of the liquid in the liquid container in an electric kettle according to an embodiment of the present invention, where the amount of liquid in the liquid container is small. [Figure 10] 1 is a diagram showing the on / off control of the print heater and the temperature transition of the liquid in the liquid container in an electric kettle according to an embodiment of the present invention, where the amount of liquid in the liquid container is large. DETAILED DESCRIPTION OF THE INVENTION

[0019] <Configuration of the electric kettle according to the embodiment of the present invention> 1 and 3, an electric kettle 100 according to an embodiment of the present invention is mainly composed of a kettle body 200 and a power base 600. Each of these components will be described in detail below.

[0020] 1. Kettle body The kettle body 200 is detachably placed on the power supply base 600. A user of the electric kettle 100 places the kettle body 200 on the power supply base 600 when wanting to boil water, and can remove the kettle body 200 from the power supply base 600 to pour the hot water into a cup, teacup, or other container. As shown in FIGS. 1 to 3, the kettle body 200 is mainly composed of a main body unit 300, a handle unit 400, and a lid unit 500. Each of these components will be described in detail below. As shown in FIGS. 1 to 3, a spout (discharge port) 301 for pouring hot water or other liquids is formed in the upper front portion of the kettle body 200.

[0021] (1) Main unit 1 to 3, main body unit 300 is mainly composed of a sidewall member 310, a liquid container 320, a bottom member 330, a heater unit 340, an ejection port forming portion 350, and a bottom sensor BS. Each of these components will be described in detail below.

[0022] (1-1) Side wall member Sidewall member 310 is a member formed of resin, metal such as stainless steel, or the like, and is generally cylindrical as shown in FIGS. 1 and 3. It forms the outer peripheral surface of main body unit 300. As shown in FIG. 3, sidewall member 310 houses liquid container 320, discharge port forming portion 350, and the like. Also as shown in FIG. 3, sidewall member 310 houses heater unit 340 together with bottom member 330. The upper end of sidewall member 310 supports the upper end of discharge port forming portion 350 as shown in FIGS. 1, 3, and 4. A notch is formed in the upper end of the rear portion of sidewall member 310, and as shown in FIG. 3, main body connecting portion 402 of handle unit 400 is fitted into this notch. A front protrusion 311 that slopes forward is formed at the top of the front portion of sidewall member 310.

[0023] (1-2)Liquid container Liquid container 320 is a member capable of storing liquid therein and is housed within sidewall member 310 as described above. As shown in FIG. 3, liquid container 320 is formed from inner wall member 321 and heater plate 322. Inner wall member 321 is a member formed from resin or metal such as stainless steel, and is substantially cylindrical. As shown in FIG. 3, it constitutes the sidewall of liquid container 320. As shown in FIGS. 3 and 4, the lower end of discharge port formation portion 350 is attached to the upper end of inner wall member 321. The inner circumferential surface of inner wall member 321 may be coated with a corrosion-resistant resin (not shown) such as fluororesin. Heater plate 322 is a metal plate that covers the lower opening of inner wall member 321 so as to close it, as shown in FIG. 3. That is, heater plate 322 constitutes the bottom of liquid container 320. As shown in FIG. 3, a print heater 341, which is one component of the heater unit 340, is disposed on the underside of the heater plate 322, and the detection portion of the bottom sensor BS protrudes from the rear of the heater plate 322 into the internal space of the liquid container 320.

[0024] (1-3) Bottom member 3, bottom member 330 constitutes the bottom of main body unit 300, is attached to the lower side of side wall member 310, and covers liquid container 320, heater unit 340, etc. from below. Bottom member 330 has an opening that exposes the lower end of power supply terminal 342.

[0025] (1-4) Heater unit As shown in Figure 3, heater unit 340 is attached to heater plate 322 of liquid container 320 and is mainly composed of print heater 341 and power supply terminal 342. Print heater 341 heats heater plate 322 of liquid container 320, thereby heating the liquid in liquid container 320. When electric kettle 100 is turned on with kettle body 200 placed on power supply base 600 and power supply terminal 342 is electrically connected to connection terminal 602 provided on power supply base 600, print heater 341 is controlled by control device CO (see Figure 6) and becomes able to heat the liquid in liquid container 320. Note that a heater unit of a conventionally known electric kettle can be used as heater unit 340.

[0026] (1-5) Discharge port forming part The outlet forming portion 350 is a substantially cylindrical member and is attached to the main body unit 300 as shown in FIGS. 1 to 3. As described above, the upper end of the outlet forming portion 350 is supported by the upper end of the sidewall member 310, and the lower end of the outlet forming portion 350 is attached to the upper end of the inner wall member 321 of the liquid container 320. Also, as shown in FIGS. 1 to 3, a front protrusion 351 that slopes upward toward the front is formed at the top of the front of the outlet forming portion 350. As shown in FIGS. 1 and 3, the front protrusion 351 is supported by the front protrusion 311 of the sidewall member 310. In this way, in the electric kettle 100 according to the embodiment of the present invention, the spout 301 is formed by a part of the outlet forming portion 350 (i.e., the front protrusion 351). Also, as shown in FIG. 4, a claw receiving portion 352 that is recessed outward is formed in the middle of the left and right portions of the outlet forming portion 350. The locking lever RL of the locking mechanism LM of the lid unit 500 is locked onto this claw receiving portion 352 (see Figure 4). Also, as shown in Figure 4, an inclined portion 353 that slopes outward is formed on the upper side of the claw receiving portion 352. The inclined portion 353 comes into contact with the locking lever RL of the locking mechanism LM of the lid unit 500 when the lid unit 500 is attached to the main body unit 300 or when the lid unit 500 is removed from the main body unit 300.

[0027] (1-6) Bottom sensor Bottom sensor BS is a general temperature sensor (e.g., a thermocouple or a thermistor) for measuring the temperature of the liquid in liquid container 320 of main unit 300. As described above, the detection portion of bottom sensor BS protrudes from the rear of heater plate 322 of liquid container 320 into the internal space of liquid container 320.

[0028] (2) Handle unit 1 to 3, the handle unit 400 is mainly composed of a grip portion 401, a main body connection portion 402, a dial mechanism 403, a control device CO, and a steam sensor SS. Each of these components will be described in detail below.

[0029] (2-1) Gripping part Grip part 401 is a member made of resin or the like, and serves as a handle when a user carries kettle body 200. Grip part 401 extends downward from the rear part of main body connecting part 402, as shown in Figures 1 to 3 .

[0030] (2-2) Main unit connection part The main body connecting portion 402 is used to connect the handle unit 400 to the main body unit 300. As described above, the main body connecting portion 402 is fitted into the notch at the upper end of the rear portion of the side wall member 310. As shown in FIG. 3, a sensor installation space 402a is formed in the front portion of the main body connecting portion 402. As shown in FIG. 3, a steam sensor SS is installed in the sensor installation space 402a. As shown in FIG. 3, the sensor installation space 402a communicates with a steam circulation space SP1 (described below) via a steam guide hole OP in a side wall portion 521 of a bottom plate member 520 of the lid unit 500.

[0031] (2-3) Dial mechanism Dial mechanism 403 is used to set the target temperature of the liquid in liquid container 320, and is connected to control device CO as shown in FIG. 6. The target temperature can be selected from a number of settings (for example, 50°C to 100°C). Dial mechanism 403 is disposed at the rear of main body connection part 402 as shown in FIGS. 1 to 3. Dial mechanism 403 also functions as a switch for turning the power of electric kettle 100 on and off when kettle main body 200 is placed on power base 600.

[0032] (2-4) Control device The control device CO includes electronic components such as a microcomputer, and as shown in FIG. 6, is connected to the bottom sensor BS of the main unit 300, the heater unit 340 of the main unit 300, the steam sensor SS, the dial mechanism 403, and the like. The microcomputer is equipped with memory for storing various programs and data such as the temperature control table Ta1 (see FIG. 7, described below). When the electric kettle 100 is turned on, the control device CO measures time, controls the print heater 341 of the heater unit 340 so that the temperature measured by the bottom sensor BS of the main unit 300 approaches the set temperature (described below), and determines that the liquid in the liquid container 320 has boiled when the temperature of the steam measured by the steam sensor SS reaches or exceeds the boiling threshold temperature. When 100°C is selected as the set temperature, the control device CO does not energize the print heater 341 when the steam sensor SS measures the boiling threshold temperature.

[0033] In the temperature control table Ta1, as shown in FIG. 7, first threshold temperature information and second threshold temperature information are associated with set temperature information. The first threshold temperature information is information indicating the temperature at which the control device CO determines whether to stop energizing the print heater 341, and the second threshold temperature information is information indicating the temperature at which the control device CO determines whether to resume energizing the print heater 341. The first threshold temperature is lower than the set temperature, and the second threshold temperature is higher than the first threshold temperature but lower than the set temperature. While FIG. 7 only shows an example of the first threshold temperature and the second threshold temperature, when the set temperature is 50°C, the first threshold temperature is 40°C and the second threshold temperature is 45°C, and when the set temperature is 60°C, the first threshold temperature is 50°C and the second threshold temperature is 55°C. Although not shown, for example, when the set temperature is 70°C, the first threshold temperature can be 66°C, when the set temperature is 80°C, the first threshold temperature can be 77°C, and when the set temperature is 90°C, the first threshold temperature can be 88°C. In other words, for a set temperature selected within a predetermined temperature range of, for example, 70°C to 90°C, the first threshold can be set so that the difference between the set temperature and the first threshold temperature becomes smaller as the set temperature increases (note that it is not necessary to set the first threshold so that the difference between the set temperature and the first threshold temperature becomes smaller as the set temperature increases). Note that there is no need to set a second threshold temperature for these set temperatures.

[0034] (2-5) Steam sensor The steam sensor SS is a general temperature sensor (e.g., a thermocouple or thermistor) for measuring the temperature of steam generated from the liquid in the liquid container 320 of the main unit 300, and as described above, is arranged in the sensor arrangement space 402a of the main body connection part 402.

[0035] (3) Lid unit As shown in FIGS. 1 to 4, the lid unit 500 is a removable lid that covers the upper part of the main body unit 300 and has a generally disk-like shape in a plan view. A user can remove the lid unit 500 from the main body unit 300 by operating a locking member 550 (described below) via an operating lever 560 provided on the lid unit 500. This allows the user to pour liquid into the liquid container 320 after removing the lid unit 500 from the main body unit 300. When heating the liquid contained in the liquid container 320, the user attaches the lid unit 500 to the main body unit 300 to create a closed space inside the liquid container 320. As shown in FIGS. 1 to 5, the lid unit 500 is mainly composed of an upper surface member 510, a bottom plate member 520, an opening / closing button 530, an opening / closing valve 540, a locking member 550, a locking mechanism LM, an operating lever 560, a sealing member 590, and a packing PK. Each of these components will be described in detail below.

[0036] (3-1) Top member As shown in FIGS. 1 to 5, the top surface member 510 is a substantially annular-shaped member and constitutes the top surface of the lid unit 500. That is, an opening is formed in the center of this top surface member 510. As shown in FIGS. 3 to 5, the open / close button 530, the cylindrical wall portion of the locking member 550, the base portion 561 of the operating lever 560, etc. are fitted into the opening of the top surface member 510. Also, as shown in FIG. 4, spring mounting portions 512 are formed on the left and right ends of the underside of the top surface member 510. As shown in FIG. 4, one end of a coil spring CS2 that urges the locking member 550 downward is fitted into the spring mounting portion 512.

[0037] (3-2) Bottom plate member As shown in FIGS. 3 to 5, bottom plate member 520 mainly constitutes the lower portion of lid unit 500 and is formed by side wall portion 521 and bottom wall portion 522. Side wall portion 521 has a generally cylindrical shape. As shown in FIGS. 3 to 5, top surface member 510 (described later) is placed on the upper side of side wall portion 521. This forms a steam distribution space SP1 surrounded by top surface member 510 and bottom plate member 520 (see FIGS. 3 and 5). In steam distribution space SP1, a distribution path (see the thick arrow in FIG. 5) for steam generated in liquid container 320 is formed. As shown in FIGS. 3 and 5, a flow path forming portion 523 is formed in the front portion of side wall portion 521. Flow path forming portion 523 is a portion that forms a flow path extending toward spout 301 of kettle body 200, i.e., discharge path DP. The flow path forming portion 523 guides the liquid in the liquid container 320 to the spout 301. Furthermore, as shown in FIG. 4, openings 521a are formed in the lower left and right portions of the side wall portion 521, allowing the tip of the locking mechanism LM to protrude through these openings 521a. Furthermore, as shown in FIGS. 3 and 5, a steam guide hole OP is formed in the rear portion of the side wall portion 521. As shown in FIG. 3, this steam guide hole OP connects the sensor placement space 402a of the main body connection portion 402 of the handle unit 400 to the steam distribution space SP1 when the lid unit 500 is attached to the main body unit 300. The bottom wall portion 522 has a substantially annular shape in plan view, and as shown in FIGS. 3 to 5, forms a stepped structure in vertical cross section. As shown in FIGS. 3 to 5, an opening / closing valve 540 is provided below the bottom wall portion 522. 3 to 5, bottom wall portion 522 abuts against packing 543 of on-off valve 540 when on-off valve 540 is in a closed state. Bottom wall portion 522 does not abut against packing 543 of on-off valve 540 when on-off valve 540 is in an open state. This makes it possible to guide the liquid in liquid container 320 to discharge path DP when on-off valve 540 is in an open state. Also, as shown in FIGS. 3 to 5, a central opening is formed in the center of bottom wall portion 522, and shaft portion 542 of on-off valve 540 is fitted into this central opening.3 and 5, rear communication hole 522a is formed in the rear portion of bottom wall portion 522 (i.e., slightly rearward of the central opening). Rear communication hole 522a abuts against packing 543 of on-off valve 540 and is closed when on-off valve 540 is closed, and is open when on-off valve 540 is open, connecting the interior space of liquid container 320 to vapor distribution space SP1. Also, as shown in FIGS. 3 and 5, steam vent 522c is formed in bottom wall portion 522 at a position rearward of rear communication hole 522a. Unlike rear communication hole 522a, steam vent 522c is always open and connects the interior space of liquid container 320 to vapor distribution space SP1. 3 and 5, a front communication hole 522b is formed in a portion of the bottom wall portion 522 forward of the central opening and rearward of the flow path forming portion 523. As shown in FIGS. 3 and 5, the front communication hole 522b communicates the steam flow space SP1 with the discharge path DP.

[0038] (3-3) Open / close button As shown in FIGS. 3 to 5, the open / close button 530 is fitted into the opening of the top member 510 and is connected to the upper end of the shaft 542 of the open / close valve 540. As shown in FIGS. 2 to 5, a cylindrical wall portion of a locking member 550 is arranged around the side wall portion of the open / close button 530. The open / close button 530 is also biased upward by a coil spring CS1 (see FIGS. 3 to 5) that is arranged so as to surround the shaft 542 of the open / close valve 540. When the user presses the open / close button 530 downward against the biasing force of the coil spring CS1, the open / close valve 540 moves downward in conjunction with the pressing action. This causes the open / close valve 540 to enter an open state.

[0039] (3-4) On-off valve As shown in FIGS. 3 to 5, the on-off valve 540 is composed of a valve main body 541, a shaft 542, and a packing 543. The valve main body 541 has a generally disk shape and is disposed below the bottom plate member 520 of the lid unit 500 as shown in FIGS. 3 to 5. The shaft 542 is a rod-shaped member extending upward from the rear of the upper surface of the valve main body 541 as shown in FIGS. 3 to 5. As described above, the shaft 542 is fitted into the central opening of the bottom wall portion 522 of the bottom plate member 520, and the upper end of the shaft 542 is connected to the on-off button 530. The packing 543 has a generally annular shape and is attached to the outer edge of the valve main body 541 as shown in FIGS. 3 to 5.

[0040] (3-5) Locking member The locking member 550 is used to lock the lid unit 500 to the main unit 300 when the lid unit 500 is attached to the main unit 300 (see FIG. 4). When the lid unit 500 is locked to the main unit 300 (hereinafter referred to as the "locked state"), the locking member 550 is biased downward by the coil spring CS2 and engages with the locking lever RL of the locking mechanism LM. As shown in FIGS. 3 to 5, the cylindrical wall portion extending upward from the center of the locking member 550 is sandwiched between the open / close button 530 and the operating lever 560, and is connected only to the operating lever 560. Therefore, the operating lever 560 and the locking member 550 move in conjunction with each other, but the open / close button 530 and the locking member 550 do not move in conjunction with each other.

[0041] (3-6) Locking mechanism The locking mechanism LM is mainly composed of a locking lever RL (see FIG. 4) and a torsion spring (not shown). The locking lever RL is rotatable around an axis AX (see FIG. 4) fixed inside the lid unit 500, and can be locked to the claw receiving portion 352 of the outlet forming portion 350 of the main unit 300 (see FIG. 4). In the locked state, the locking lever RL is engaged with a locking member 550, and cannot be rotated from the state where it is locked to the claw receiving portion 352 of the outlet forming portion 350 of the main unit 300. The torsion spring biases the locking lever RL in the direction of locking it to the claw receiving portion 352 of the outlet forming portion 350 of the main unit 300, and is disposed on the outer periphery of the axis AX.

[0042] Here, we will explain the operation for releasing the locked state of the electric kettle 100 according to the embodiment of the present invention. First, the user hooks the fingers of one hand around the flange 562 of the operating lever 560 and lifts the operating lever 560 upward. At this time, in conjunction with the movement of the operating lever 560, the locking member 550 is also lifted upward against the biasing force of the coil spring CS2. This releases the engagement between the locking member 550 and the locking lever RL of the locking mechanism LM, allowing the locking lever RL of the locking mechanism LM to rotate about the axis AX, thereby releasing the locked state. Then, while keeping the fingers hooked on the flange 562 of the operating lever 560, the user further lifts the operating lever 560 upward, thereby lifting the entire lid unit 500 upward, and can remove the lid unit 500 from the main body unit 300.

[0043] (3-7) Control lever The operating lever 560 is operated by the user to release the locked state, and as described above, is connected to the locking member 550. As shown in FIGS. 3 to 5, the operating lever 560 is formed of a base portion 561 and a flange portion 562. The base portion 561 is substantially cylindrical and, as shown in FIGS. 3 to 5, is fitted into the opening of the upper surface member 510. The flange portion 562 is a substantially disk-shaped portion with which the user supports the operating lever 560 with their fingers, and, as shown in FIGS. 3 to 5, extends outward from the upper end portion of the base portion 561. As shown in FIGS. 3 to 5, an opening is formed in the center of the flange portion 562, and the open / close button 530 is exposed through this opening. In addition, a groove is formed in the underside of the flange portion 562. This groove functions as a non-slip surface for the user's fingers.

[0044] (3-8) Sealing material Seal member 590 is an annular member made of an elastic material such as rubber or elastomer, and as shown in Figures 3 to 5, is attached to the outer periphery of the lower surface of bottom wall portion 522 of bottom plate member 520. As shown in Figures 3 and 4, seal member 590 serves to close the gap between liquid container 320 and bottom plate member 520 (in other words, to keep liquid container 320 and bottom plate member 520 tightly sealed) when lid unit 500 is attached to main body unit 300.

[0045] (3-9) Gasket The packing PK is a member made of a flexible material and serves as a check valve that blocks the front communication hole 522b of the bottom plate member 520 from below (see FIGS. 3 and 5). When steam generated in the liquid container 320 flows into the steam distribution space SP1 through the steam port 522c of the bottom plate member 520 and flows to the front side of the steam distribution space SP1 (see the thick arrow in FIG. 5), the packing PK is pushed by the steam and bends downward, opening the front communication hole 522b of the bottom plate member 520.

[0046] 2.Power supply stand The power supply base 600 serves as a power supply unit that supplies electricity to the kettle body 200, and also serves as a base for the kettle body 200. As shown in FIGS. 1 and 3, the power supply base 600 is mainly composed of a power cord 601, a power plug (not shown), and a connection terminal 602. When the kettle body 200 is placed on the power supply base 600 and the power supply terminal 342 of the heater unit 340 is connected to the connection terminal 602, a power supply circuit is formed. When the electric kettle 100 is turned on, electricity can be applied to the heater unit 340 and the control device CO. Note that the power supply base 600 can have a configuration similar to that of power supply bases for conventionally known electric kettles.

[0047] <Regarding the processing of the control device in the electric kettle according to the embodiment of the present invention> The process SA of the control device CO when controlling the print heater 341 of the heater unit 340 so that the measured temperature of the liquid approaches the set temperature will be described below with reference to FIG. 8. As a preliminary step, the user removes the lid unit 500 from the main unit 300 and pours liquid into the liquid container 320 up to the maximum liquid volume. The user then attaches the lid unit 500 to the main unit 300 and locks it in place, places the kettle body 200 on the power base 600, turns the dial mechanism 403 to set the set temperature, and turns on the electric kettle 100. At this time, the control device CO compares the set temperature information with the temperature control table Ta1 and obtains the first or second threshold temperature information corresponding to the set temperature information. If the set temperature is 100°C, the control device CO does not execute process SA but executes a boiling detection process (not shown). In the boiling detection process, the control device CO energizes the print heater 341 until the steam sensor SS measures the boiling judgment temperature, and stops energizing the print heater 341 once the steam sensor SS measures the boiling judgment temperature.

[0048] (Step Sa1) First, the control device CO energizes the print heater 341. This heats the liquid in the liquid container 320. The measured temperature is measured by the bottom sensor BS, and the control device CO receives the measured temperature information from the bottom sensor BS.

[0049] (Step Sa3) The control device CO determines whether the measured temperature has reached a first threshold temperature, which is, for example, 40° C. when the set temperature is 50° C. (see FIG. 7).

[0050] -If step Sa3 is YES- If the control device CO determines that the measured temperature has reached the first threshold temperature, the process proceeds from step Sa4.

[0051] -If step Sa3 is NO- If the control device CO determines that the measured temperature has not reached the first threshold temperature, the process is repeated from step Sa1.

[0052] (Step Sa4) The control device CO determines whether the set temperature is equal to or higher than a reference temperature (for example, 70°C or higher). If the set temperature is equal to or higher than the reference temperature, the control device CO executes the process from step Sa11 onward, and if the set temperature is lower than the reference temperature, the control device CO executes the process from step Sa5 onward.

[0053] (Step Sa5) The control device CO stops powering the print heater 341. Note that the state in which powering the print heater 341 has been stopped means that powering the print heater 341 may be resumed depending on the result of the determination condition in step Sa9, which will be described later.

[0054] (Step Sa7) The control device CO determines whether a waiting time has elapsed since power supply to the print heater 341 was stopped. The waiting time is the time required for the effects of thermal convection that may occur in the liquid container 320 to decrease immediately after power supply to the print heater 341 is stopped, and is, for example, about 5 seconds.

[0055] -If step Sa7 is YES- If the control device CO determines that the standby time has elapsed since the power supply to the print heater 341 was stopped, the process starts from step Sa9.

[0056] -If step Sa7 is NO- If the control device CO determines that the standby time has not elapsed since the power supply to the print heater 341 was stopped, the process of step Sa7 is repeated.

[0057] (Step Sa9) The control device CO determines whether the measured temperature has reached the second threshold temperature. For example, the second threshold temperature is 45°C when the set temperature is 50°C (see FIG. 7). Note that the second threshold temperature is higher than the first threshold temperature because the measured temperature rises (overshoots) due to the influence of residual heat of the print heater 341 even after power is turned off to the print heater 341.

[0058] -If step Sa9 is YES- If the control device CO determines that the measured temperature has reached the second threshold temperature, the process proceeds from step Sa11.

[0059] -If step Sa9 is NO- If the control device CO determines that the measured temperature has not reached the second threshold temperature, the process proceeds from step Sa13.

[0060] (Step Sa11) The control device CO stops powering the print heater 341. Then, the process SA ends here.

[0061] (Step Sa13) The control device CO supplies power to the print heater 341 .

[0062] (Step Sa15) The control unit CO determines whether the measured temperature reaches a second threshold temperature.

[0063] -If step Sa15 is YES- If the control device CO determines that the measured temperature has reached the second threshold temperature, the process from step Sa11 described above is executed.

[0064] -If step Sa15 is NO- If the control device CO determines that the measured temperature has not reached the second threshold temperature, the process is repeated from step Sa13.

[0065] FIG. 9 shows the on / off control of print heater 341 and the temperature transition of the liquid in liquid container 320 when the answer to step Sa9 is YES. FIG. 9 shows that the measured temperature reaches the second threshold temperature after the standby time has elapsed since power supply to print heater 341 was stopped. Note that the amount of temperature rise of the liquid after power supply to print heater 341 is stopped (hereinafter referred to as the "temperature rise when power is off") is generally large when the amount of liquid in liquid container 320 is small and small when the amount of liquid in liquid container 320 is large. Therefore, FIG. 9 shows that the amount of liquid in liquid container 320 is relatively small. Furthermore, FIG. 9 shows that the measured temperature approaches the set temperature even when power supply to print heater 341 is not resumed after power supply to print heater 341 is stopped.

[0066] FIG. 10 shows the on / off control of print heater 341 and the temperature transition of the liquid in liquid container 320 when the result of step Sa9 is NO. FIG. 10 shows that the measured temperature has not reached the second threshold temperature even after the standby time has elapsed since power to print heater 341 was stopped. Therefore, FIG. 10 shows that the amount of liquid in liquid container 320 is relatively large. FIG. 10 also shows that power is again supplied to print heater 341 after power to print heater 341 is stopped, and that power is no longer supplied to print heater 341 when the measured temperature reaches the second threshold temperature, causing the measured temperature to approach the set temperature.

[0067] <Features of the electric kettle according to the embodiment of the present invention> (1) In the electric kettle 100 according to the embodiment of the present invention, when the control device CO determines that the measured temperature has reached the first threshold temperature, it stops supplying power to the print heater 341, and after stopping supplying power to the print heater 341, it determines whether the measured temperature has reached the second threshold temperature. If the control device CO determines that the measured temperature has reached the second threshold temperature, it does not supply power to the print heater 341, and if it determines that the measured temperature has not reached the second threshold temperature, it supplies power to the print heater 341 but then does not supply power to the print heater 341. As a result, in the electric kettle 100, heating is performed appropriately depending on the amount of liquid, etc., and it is possible to complete heating of the liquid with minimal deviation from the set temperature regardless of the amount of liquid, etc.

[0068] (2) In the electric kettle 100 according to the embodiment of the present invention, the control device CO determines whether the measured temperature has reached the second threshold temperature after a waiting time has elapsed since power supply to the print heater 341 was stopped. Therefore, in this electric kettle 100, the measured temperature can be measured as accurately as possible after power supply to the print heater 341 is stopped.

[0069] (3) In the electric kettle 100 according to the embodiment of the present invention, the control device CO determines whether the set temperature is equal to or higher than a reference temperature. If the control device CO determines that the set temperature is equal to or higher than the reference temperature, it stops supplying power to the print heater 341 when the measured temperature reaches a first threshold temperature. If the control device CO determines that the set temperature is lower than the reference temperature, it stops supplying power to the print heater 341 when the measured temperature reaches the first threshold temperature. Therefore, in this electric kettle 100, it is possible to complete heating of the liquid while minimizing deviation from the set temperature regardless of the amount of liquid, taking into consideration that as the set temperature increases, the gap between the set temperature and room temperature becomes larger, making it easier for the liquid temperature to drop.

[0070] (4) In the electric kettle 100 according to the embodiment of the present invention, the first threshold temperature can be set for a plurality of set temperatures so that the difference between the set temperature and the first threshold temperature decreases as the set temperature increases. Therefore, in the electric kettle 100, the first threshold temperature is set to a value appropriate for bringing the temperature of the liquid at the completion of heating close to the set temperature, depending on the selected set temperature.

[0071] <Modification> (A) In the electric kettle 100 according to the previous embodiment, the control device CO determines whether the standby time has elapsed in step Sa7 of process SA. However, the control device CO may determine whether another condition is met, rather than determining whether the standby time has elapsed in step Sa7 of process SA. The other condition may be, for example, whether, when a certain measured temperature after step Sa5 of process SA is set as a reference measured temperature, the measured temperature after the reference measured temperature is within a range of ±b°C (e.g., ±1°C) of the reference measured temperature within a seconds (e.g., 3 seconds).

[0072] (B) Although not mentioned in the electric kettle 100 according to the previous embodiment, if the control device CO determines in step Sa15 of process SA that the measured temperature has reached the second threshold temperature, it may stop powering the print heater 341 before proceeding to step Sa11. The control device CO may then determine whether the measured temperature has reached the third threshold temperature after a waiting time has elapsed since powering the print heater 341 was stopped. The length of this waiting time may or may not be the same as the length of the waiting time in step Sa7, and the third threshold temperature is higher than the second threshold temperature. If the control device CO determines that the measured temperature has reached the third threshold temperature, it may proceed to step Sa11 and not power the print heater 341. If the control device CO determines that the measured temperature has not reached the third threshold temperature, it may resume powering the print heater 341. If the control device CO determines that the measured temperature has reached the third threshold temperature after energizing the print heater 341, it may proceed to step Sa11 and stop energizing the print heater 341, or it may stop energizing the print heater 341, wait a waiting time, and then determine whether the measured temperature has reached a fourth threshold temperature higher than the third threshold temperature, and repeat the above-described process. In this way, the control device CO may use an nth threshold temperature approaching the set temperature in addition to the first and second threshold temperatures in process SA. In such a case, the nth threshold temperature must be associated with the set temperature in the temperature control table Ta1.

[0073] Furthermore, even if the control device CO determines in step Sa9 of process SA that the measured temperature has reached the second threshold temperature, it may return to energizing the print heater 341 until the measured temperature reaches the third threshold temperature before proceeding to step Sa11. The third threshold temperature is higher than the second threshold temperature. When the measured temperature reaches the third threshold temperature, the control device CO may stop energizing the print heater 341 and wait a waiting time before determining whether the measured temperature has reached the fourth threshold temperature. The length of this waiting time may or may not be the same as the length of the waiting time in step Sa7. When the control device CO determines that the measured temperature has reached the fourth threshold temperature, it may return to step Sa11 and stop energizing the print heater 341, or it may repeat the above-described process of returning to energizing the print heater 341 until the measured temperature reaches a fifth threshold temperature, which is higher than the fourth threshold temperature.

[0074] (C) In the electric kettle 100 according to the previous embodiment, if step Sa4 of process SA returns YES (i.e., if the measured temperature is equal to or higher than the reference temperature), the control device CO prevents further power supply to the print heater 341. However, after executing step Sa3, the control device CO may execute step Sa5 regardless of the set temperature in degrees Celsius. In other words, step Sa4 may be omitted from process SA. In such a case, the second threshold temperature must be set in the temperature control table Ta1 even for measured temperatures equal to or higher than the reference temperature.

[0075] (D) In the electric kettle 100 according to the previous embodiment, if step Sa9 of process SA returns NO (if it is determined that the measured temperature has not reached the second threshold temperature), the control device CO energizes the print heater 341 until the measured temperature reaches the second threshold temperature, and then does not energize the heating unit. However, if step Sa9 of process SA returns NO, the control device CO may energize the print heater 341 until the measured temperature reaches a temperature other than the second threshold temperature (for example, a temperature lower than the second threshold temperature and higher than the measured temperature when the print heater 341 was energized in step Sa13 of process SA, or a temperature higher than the second threshold temperature and lower than the set temperature).

[0076] (E) In the electric kettle 100 according to the previous embodiment, when 100°C is selected as the set temperature, the control device CO does not energize the print heater 341 if the steam sensor SS measures the boiling threshold temperature. However, when 100°C is selected as the set temperature, the control device CO may also not energize the print heater 341 if the bottom sensor BS measures a first threshold temperature (for example, a temperature that is the same as or approximately the same as the set temperature, such as 100°C or 99°C).

[0077] (F) In the electric kettle 100 according to the previous embodiment, the control device CO determines whether the set temperature is equal to or greater than the reference temperature in step Sa4 of process SA. However, the control device CO may determine whether the set temperature is equal to or greater than the reference temperature before performing process SA, i.e., when the set temperature is set. If the control device CO determines that the set temperature is equal to or greater than the reference temperature, it may execute only steps Sa1, Sa3, and Sa11 of process SA. If the control device CO determines that the set temperature is less than the reference temperature, it may execute process SA without step Sa4. Alternatively, the control device CO may determine whether the set temperature is equal to or greater than the reference temperature when the set temperature is set at any timing between the start of process SA and the execution of step Sa3.

[0078] (G) Although not mentioned in the electric kettle 100 according to the previous embodiment, a threshold temperature may be set for the set temperature so that the difference between the set temperature and the temperature at which the control device CO determines not to energize the print heater 341 (referred to as the "criterion temperature") decreases as the set temperature increases. The threshold temperature for a set temperature less than the reference temperature is the second threshold temperature, and the threshold temperature for a set temperature equal to or greater than the reference temperature is the first threshold temperature. For example, if the reference temperature is 70°C, the second threshold temperature may be 44°C for a set temperature of 50°C, the second threshold temperature may be 55°C for a set temperature of 60°C, the first threshold temperature may be 66°C for a set temperature of 70°C, the first threshold temperature may be 77°C for a set temperature of 80°C, and the first threshold temperature may be 88°C for a set temperature of 90°C. Note that when modification (C) is applied, the threshold temperature is the second threshold temperature regardless of the set temperature.

[0079] (H) In the electric kettle 100 according to the previous embodiment, the detection portion of the bottom sensor BS protrudes from the heater plate 322 of the liquid container 320 into the interior space of the liquid container 320. However, the detection portion of the bottom sensor BS may protrude from the inner wall member 321 of the liquid container 320 into the interior space of the liquid container 320, as long as it is positioned below the liquid level of the liquid contained in the liquid container 320.

[0080] (I) In the electric kettle 100 according to the previous embodiment, the print heater 341 is used to heat the liquid in the liquid container 320. However, instead of the print heater 341, other heaters such as a sheath heater may be used to heat the liquid in the liquid container 320.

[0081] (J) In the electric kettle 100 according to the previous embodiment, the dial mechanism 403 functions as a switch for turning on / off the power of the electric kettle 100. However, the switch for turning on / off the power of the electric kettle 100 may be disposed on the power base 600.

[0082] (K) In the above embodiment, the present invention is applied to the electric kettle 100, but the present invention may also be applied to other liquid heaters such as electric pots.

[0083] The above modifications may be applied alone or in combination. [Explanation of symbols]

[0084] 100 Electric kettle (liquid heater) 320 Liquid containers 341 Print heater (heating unit) 403 Dial mechanism (temperature setting part) BS Bottom sensor (temperature measurement part) CO control device (control unit)

Claims

1. A liquid container; a heating unit that heats the liquid stored inside the liquid container; a temperature measuring unit for measuring the temperature of the liquid; a temperature setting unit for setting a set temperature; a control unit that controls the heating unit based on the temperature measured by the temperature measuring unit, When the control unit determines that the measured temperature has reached a first threshold temperature that is lower than the set temperature, it stops supplying power to the heating unit, and after stopping supplying power to the heating unit, it determines whether the measured temperature has reached a second threshold temperature that is higher than the first threshold temperature and lower than the set temperature, and if it determines that the measured temperature has reached the second threshold temperature, it does not supply power to the heating unit, and if it determines that the measured temperature has not reached the second threshold temperature, it does not supply power to the heating unit after supplying power to the heating unit.This liquid heater is capable of doing so.

2. The liquid heater according to claim 1 , wherein the temperature measurement unit measures the measured temperature after a standby time has elapsed when measuring the measured temperature after the control unit stops supplying power to the heating unit.

3. The liquid heater of claim 1 or 2, wherein the control unit, when determining that the measured temperature has reached the first threshold temperature, determines whether the set temperature is equal to or higher than a reference temperature, and if it determines that the set temperature is equal to or higher than the reference temperature, does not supply power to the heating unit; when determining that the set temperature is lower than the reference temperature, determines whether the measured temperature has reached the second threshold temperature after stopping power supply to the heating unit, and if it determines that the measured temperature has reached the second threshold temperature, does not supply power to the heating unit; and if it determines that the measured temperature has not reached the second threshold temperature, does not supply power to the heating unit after powering on the heating unit.

4. The liquid heater of claim 3, wherein the temperature setting unit is capable of selecting the set temperature from a plurality of set temperatures, and for the plurality of set temperatures that are equal to or higher than the reference temperature, the difference between the set temperature and the first threshold temperature becomes smaller as the set temperature becomes higher.

5. A liquid heater as described in Claim 3, wherein the temperature setting unit is capable of selecting the set temperature from among a plurality of set temperatures, and for a plurality of set temperatures that are less than a reference temperature, the difference between the set temperature and the second threshold temperature becomes smaller as the set temperature becomes higher.

6. A liquid heater as described in any one of claims 1 to 3, wherein the temperature setting unit is capable of selecting the set temperature from a plurality of set temperatures, and for the plurality of set temperatures, the difference between the set temperature and the first threshold temperature becomes smaller as the set temperature becomes higher.

7. A liquid heater described in any one of claims 1 to 3, wherein the temperature setting unit is capable of selecting the set temperature from a plurality of set temperatures, and for the plurality of set temperatures, the difference between the set temperature and the second threshold temperature becomes smaller as the set temperature becomes higher.

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