JP3247039B2 - Liquid container liquid level detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the amount of liquid in a liquid container such as an electric pot.

[0002]

2. Description of the Related Art Conventionally, for example, a liquid level detecting device for an electric pot detects a liquid-free (empty heating) state by a liquid level sensor provided on a water level tube, and a liquid level detecting device provided on a container bottom when heated by a heater. Some systems detect a liquid-out state when an abnormal temperature rise is detected by a temperature sensor.

[0003]

However, in the former case, it is necessary to provide a liquid level sensor in the water level tube, so that parts and manufacturing costs increase. In addition, when the water level pipe also serves as a water pump, there is a problem that the liquid absence state cannot be detected during discharge. On the other hand, in the latter case, the container is temporarily burned empty, so that the vessel is not a little damaged and
There is a problem that detection takes time. The present invention has been made in view of such a problem, and an object of the present invention is to provide a liquid container liquid amount detection device capable of detecting a liquid amount in a short time with an inexpensive configuration without damaging a container. Make it an issue.

In order to achieve the above object, the present invention comprises a container for containing a liquid, an electric pump for discharging or circulating the liquid contained in the container, and a motor for driving the electric pump. In the liquid container, a plurality of sets of series resistors are connected in parallel between both terminals of the motor, and a voltage value applied to the motor is detected by detecting a divided voltage at a midpoint of each series resistor, This is to detect the amount of the liquid contained in the container.

In the apparatus of the present invention having the above structure, when the electric pump is driven to discharge or circulate the liquid in the container, the voltage value applied to the electric pump varies depending on the amount of the liquid in the container. Therefore, by detecting this voltage value at a plurality of points, the liquid amount is detected.

[0006]

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an electric pot provided with a liquid amount detection device according to the present invention. A water heater 2 and a warming heater 3 are provided at the bottom of the inner container 1 in which water is stored, and a pumping tube 5 serving as a water level tube from the bottom of the inner container 1 via an electric pump 4 is provided. The pump 1 is erected on the side of the vessel 1, and the upper end of the water pump 5 communicates with a spout 6 that opens downward. On the front upper surface of the electric pot, a discharge switch 7 for driving the electric pump 4 to discharge water in the inner container 1 and a switch for reheating the water in the inner container 1 to boil the water. A reboil switch 8 is provided, and the inner container 1
A control device 9 including a liquid amount detection device of the present invention is provided below the control device.

FIG. 2 is a circuit diagram of the control device 9. In this figure, a water heater 2 is connected to a commercial AC power supply 10 via a relay contact 11a. One terminal of the power supply 10 is connected to a normally closed contact of the discharge switch 7 via a first triac 12, and a second triac 13, a motor 14 for driving an electric pump,
The discharge switch 7 is connected to the normally open contact via the diode 15, and the common contact of the discharge switch 7 is connected to the other terminal of the power supply 10 via the heat retaining heater 3.

[0009] The rectifier circuit (not shown) connected to a power supply 10, together with the microcomputer 16 is connected, the transistor Q _H and the relay coil 11b for heating water heater drive is connected, the base of the transistor Q _H microcomputer It is connected to 16 water heater control signal output terminals A. The heat retention heater control signal output terminal B of the microcomputer 16 is connected to the gate terminal of the first triac 12, and the motor control signal output terminal C is connected to the gate terminal of the second triac 13.

Between both terminals of the motor 14, a 15V constant voltage diode 17 and an electric field capacitor 18 are connected in parallel, and series resistors R ₁ , R ₂ , series resistors R ₃ ,
R ₄ , series resistors R ₅ and R ₆ , and series resistors R ₇ and R ₈ are connected in parallel. Also, the positive side of the motor 14 discharge detection transistor Q _1, a medium amount detection transistor Q _2, the respective emitter terminals of the small amount detection transistor Q _3, and the liquid without detection transistor Q ₄ is connected,
The collector terminals of the transistors Q ₁ , Q ₂ , Q ₃ , Q ₄ are respectively a discharge detection signal input terminal S ₁ , a medium amount detection signal input terminal S ₂ , a small amount detection signal input terminal S _{3 of} the microcomputer 16, It is connected without the detection signal input terminal S _4. The base terminals of the transistors Q ₁ , Q ₂ , Q ₃ , and Q ₄ are respectively connected to the midpoints of the series resistances R ₁ and R ₂ and the series resistance R
_3, the middle point of R _4, the middle point of the series resistors R _5, R _6, and is connected to the midpoint of the series resistors R _7, R _8. In addition, reference numerals 19 and 20 denote buzzers and lamps for informing of empty firing.

Next, the operation of the electric pot having the above configuration will be described. The inner container 1 the water is placed in, or when reboiling switch 8 is pressed, the microcomputer 16 turns on the transistor Q _H to output a kettle heater-on signal from the output terminal A, and excites the relay coil 11b Relay The contact 11a is closed, and the heater 2 is energized. At the same time, the microcomputer 16 outputs a warming heater ON signal from the output terminal B, turns on the first triac 12, and energizes the warming heater 3. Thereby, the water heater 2 and the heat retaining heater 3 perform the water heating. When the sensor (not shown) for detecting the water boiling end temperature, the microcomputer 16 turns off the transistor Q _H to output a kettle heater off signal from the output terminal A, open the relay contacts 11a to demagnetize the relay coil 11b, kettle heater 2 At the same time, the power supply to the first triac 12 is turned off by outputting a heat retention heater off signal from the output terminal B. Then, the heat retaining temperature is maintained by controlling the heat retaining heater 3.

When the discharge switch 7 is turned on while water is being heated or kept warm, the motor 14 is driven and the electric pump 4 discharges water in the inner container 1 from the inlet 6 through the water pump 5.
At this time, the current value and the voltage value flowing through the motor 14 of the electric pump 4 change according to the liquid amount as shown in Table 1.

[Table 1] Liquid volume (L) Current value (mA) Voltage value (V) 3.0 200 12.4 1.5 220 12.2 0.6 230 12.10 130 15.0

That is, when the amount of liquid is large, the head H required to discharge water from the liquid level of the pumping pipe 5 to the uppermost point of the pumping pipe 5 is small, so that the load is relatively small. But,
As the liquid amount decreases, the head H increases and the load increases, so that the current value increases and the voltage value decreases. However, in the presence of water, the current value does not fall below 150 mA and the voltage value does not exceed 14V. And when the water disappears, the current value rapidly decreases to less than 150 mA,
The voltage value increases and exceeds 14V.

In order to detect the amount of liquid and the absence of liquid by utilizing the change of the current value and the voltage value, particularly the change of the voltage value according to the load state, in the present embodiment, R ₁ : R ₂ ,
The ON voltage and the OFF voltage of the transistors Q ₁ , Q ₂ , Q ₃ , and Q ₄ are set by the ratio of R ₃ : R ₄ , R ₅ : R ₆ , and R ₇ : R ₈ .

Specifically, when the voltage applied to the motor 14 is in a transitional period, the series resistance R of a certain voltage value (8 V)
_1, divided voltage at the midpoint of R ₂ is in the ON voltage of the discharge detection transistor Q _1. The series resistance R of the voltage value (12.2 V) applied to the motor 14 when the liquid amount is a medium amount
_3, divided voltage at the midpoint of the R ₄ is in the off-voltage of the medium-amount detection transistor Q _2. Similarly, when the liquid amount is small, the divided voltage at the midpoint between the series resistances R ₅ and R ₆ of the voltage value (12.1 V) applied to the motor 14 is equal to the off voltage of the small liquid amount detection transistor Q _3. Has become. When the liquid amount is zero and there is no water, the divided voltage at the midpoint between the series resistances R ₇ and R ₈ of the voltage value (14.0 V) applied to the motor 14 is the on-voltage of the liquid absence detection transistor Q ₄ . It has become. The signal detected by each of the transistors _{Q 1, Q 2, Q 3} , Q 4 is input to the micro each detection terminal S ₁ of the computer _{16, S 2, S 3,} S 4.

FIG. 3 shows a change in the voltage value applied to the motor 14 when the discharge switch 7 is turned on to continuously discharge water in the inner container 1 from full to empty. In the figure, n is the time before the discharge switch 7 is turned on, and a to f are the times after the discharge switch 7 is turned on. When the discharge switch 7 is turned on in the full state, a to c shift instantaneously.

The transistor Q at each time point n, a to f
The operating states of ₁ , Q ₂ , Q ₃ and Q ₄ are as shown in Table 2.

Table 2 amount in the full amount small amount without n a b c d e f Q 1 OFF ON ON ON ON ON ON Q ₂ OFF OFF OFF ON OFF OFF ON Q ₃ OFF OFF ON ON ON OFF ON Q ₄ Off Off Off Off off off on

Next, the operation of detecting the liquid amount or the absence of the liquid will be described with reference to FIG.
This will be described according to the flowchart shown in FIG. First, it is determined whether the transistor Q ₄ is turned on at step 101, detects that the liquid no in step 102 if the on,
The user is notified of the idle heating state by a buzzer sound or blinking of a lamp, and a motor stop signal is output from the output terminal C at step 103 to turn off the second triac 13 and stop the motor 14. At the same time, the power supply to the heat retaining heater 3 is stopped, and the reboil switch 8 is turned off.
Prohibit reception of Next, in step 104, the process waits until the reset switch is turned on. If the reset switch is turned on, the process returns to step 101 to resume the liquid amount detection. As this reset switch, a single reset switch can be provided, but the reboil switch 8 may also be used, or the reset may be activated by turning on the power.

[0019] Unless transistor Q ₄ is turned on at step 101, the transistor Q in step 105
_It is determined whether ₁ has been turned on. Here, if the transistor Q ₁ is not turned back to step 101, if on, it detected to be in discharge operation at step 106, after the display in discharge by the lamp 20 or the like, at step 107 transistor Q _3, it is determined whether or not turned off. Here, if the off transistor Q _3, and detected a small amount at step 108, returns to step 101 by performing a solution amount indicator by the lamp 20 and the like. If the transistor Q ₃ is not turned off and the transistor Q in step 109
_It is determined whether or not ₂ is turned off. Here, if the transistor Q ₂ is long off, it detects the medium heavy at step 110, by performing the liquid amount display by the lamp 20 or the like Step 10
Return to 1. If the transistor Q ₂ is not turned off, the process returns to step 101 to repeat the above steps.

In the above-described embodiment, the voltage value applied to the motor 14 is used to detect the liquid amount, but the liquid amount may be detected based on the current value flowing through the motor 14. In this case, a current sensor is used instead of the series resistor and transistor of the above embodiment. Further, in the above embodiment, the load state of the pump for discharging is detected, but there is no problem even if the load state of the pump provided in the circulation path is detected.

As is apparent from the above description, according to the present invention, the amount of liquid is detected only by detecting the voltage applied to the electric pump at a plurality of points while driving the electric pump to discharge the liquid. Therefore, the configuration is simple and inexpensive, and detection can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an electric pot provided with a liquid amount detection device according to the present invention.

FIG. 2 is a control circuit diagram of the electric pot of FIG.

FIG. 3 is a diagram showing a temporal change of a voltage value.

FIG. 4 is a flowchart showing an operation of detecting a liquid amount.

[Explanation of symbols]

1 inner container, 4 electric pump, 14 motor, 16 microcomputer, 19 buzzer, 20 lamp, Q
₁ : Discharge detecting transistor, Q ₂ : Medium amount detecting transistor, Q ₃ : Small amount detecting transistor, Q ₄ : Liquid absence detecting transistor, R _{1 to} R ₈ : Voltage detecting resistors.

Continuation of the front page (56) References JP-A-7-163470 (JP, A) JP-A-5-23375 (JP, A) JP-A-6-137675 (JP, A) , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) A47J 27/21 101 F24H 1/00

Claims (1)

(57) [Claims] 1. A liquid container comprising a container for storing a liquid, an electric pump for discharging or circulating the liquid stored in the container, and a motor for driving the electric pump, wherein both terminals of the motor are provided. A plurality of series resistors are respectively connected in parallel between them, and a voltage value applied to the motor is detected by detecting a divided voltage at a midpoint of each series resistor, and a liquid amount of the liquid contained in the container is detected. A liquid amount detection device for a liquid container, characterized by detecting the following.