JP2736130B2 - Electric water heater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric water heater for performing water heating.

2. Description of the Related Art In a conventional electric water heater, as shown in, for example, Japanese Utility Model Application Laid-Open No. 64-27623, an aluminum foil is wrapped around an outer surface of a glass tube which communicates with a container. An electrode was formed with the water on the inner surface of the sample, and a change in capacitance due to a change in water level was detected. Water supply detecting means for detecting that the amount of water is low (below the water supply position) is, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 61-10150.
ED and phototransistor, water in the water level tube is infrared
Detecting that the phototransistor is turned on and off by refracting the LED light and stopping the heating of the heating means,
We were informing of water supply. Also, for too much water,
For example, as shown in FIG. 5 (a), a mark 52 is provided at a position of the rated water amount on the inner surface of the container 51, and the mark A is provided at a portion A of the full water display position in the water level confirmation portion 54 of the display plate 53 for viewing the water level in the container 51. As shown in FIG. 5 (b), the display was full. Boiling detection means for detecting boiling is disclosed in, for example, JP-A-59-56.
As disclosed in Japanese Patent No. 631, a change in temperature rise due to boiling of a temperature-sensitive element provided on the outer bottom of the container is detected, and heating of the heating means is stopped and the boiling is notified.

Problems to be Solved by the Invention However, in such a conventional method, in the detection of the amount of hot water, variations in the thickness of the glass tube and variations in capacitance due to variations in the capacitance of the wiring are large, and the accuracy of the detection of the amount of hot water is not good. Was. In addition, in water supply detection, the water surface must be visible from the outside in order for the user to check the water level, and disturbance light is likely to be incident on the phototransistor, and it should not operate in bright places such as direct sunlight. was there. In addition, in the full water display, when the water is filled beyond the mark, the boiling water may overflow at the time of boiling. Further, in the detection of boiling, the thermal response characteristics of the temperature-sensitive element are poor, and it takes time to detect the boiling even when the boiling is started.

The present invention solves such a problem, and measures the time difference between the ultrasonic wave generated from the ultrasonic sensor and the reflected wave from the water surface to detect the amount of hot water, the detection of water supply or full water, and the detection of boiling. It is an object of the present invention to provide an electric water heater that can be used.

Means for Solving the Problems In order to solve the above problems, an electric water heater according to the present invention comprises a container containing a liquid, a heating unit for heating the liquid in the container, and an energization control unit for controlling the energization of the heating unit. When,
An ultrasonic sensor installed at the bottom of the container, a transmitting unit that transmits a transmission signal to the ultrasonic sensor, a receiving unit that receives a signal from the ultrasonic sensor, and a receiving unit that transmits and then receives the signal And a time measuring means for measuring a time until the heating means is stopped when the measured value of the time measuring means is less than the first set time. is there.

Further, a container for storing the liquid, a heating unit for heating the liquid in the container, an energization control unit for controlling the energization of the heating unit, an ultrasonic sensor installed at the bottom of the container, and a transmission signal to the ultrasonic sensor Transmitting means for transmitting a signal from the ultrasonic sensor, a receiving means for receiving a signal from the ultrasonic sensor, and a time measuring means for measuring a time from when the transmitting means transmits to when the receiving means receives the signal. If the value exceeds the second set time, an off signal is output to the power supply control means, and the heating means is stopped.

Further, a container for containing the liquid, a heating unit for heating the liquid in the container, an energization control unit for controlling the energization of the heating unit, an ultrasonic sensor installed at the bottom of the container, and a transmission signal to the ultrasonic sensor Transmitting means for transmitting a signal from the ultrasonic sensor, and time measuring means for measuring the time from transmission by the transmitting means to reception by the receiving means, wherein the receiving means When it stops detecting
The heating means is stopped.

Operation With the above configuration, the time proportional to the liquid amount is measured by the time measuring means, so that the liquid amount can be calculated only by multiplying by a constant, and the liquid amount can be accurately displayed.

In addition, the water supply can be detected by comparing the measured time with the first set time, the full water can be detected by comparing the measured time with the second set time, and the measured time can be compared with the second set time. Boiling can be detected by comparing with a long set third set time.

As described above, the ultrasonic sensor can realize the liquid amount detection, the water supply and the full water detection, and the boiling detection, which have been conventionally detected by several kinds of sensors.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway side view of an electric water heater according to one embodiment of the present invention. In FIG. 1, a heating means 2 for heating water in a container 1 is provided on an outer bottom portion of a container 1 for containing water,
An ultrasonic sensor 4 that emits ultrasonic waves into the container 1 and receives reflected waves from the water surface 3 is provided.

FIG. 2 is a diagram showing an example of a circuit of the electric water heater. In FIG. 2, an energization control means 5 for controlling the energization of the heating means 2 is a relay contact connected in series with the heating means 2.
5a and a relay coil 5b for driving the relay contact 4a. The transmitting means 6 applies a high-frequency signal a (here, a pulse width of 10 μs, a frequency of 4 MHz and a repetition period of 1 ms) to the ultrasonic sensor 4. The receiving means 7 receives the reflected wave signal b received by the ultrasonic sensor 4, amplifies it, shapes the waveform, and outputs it. The time measuring means 8 measures the time from when the transmitting means 6 transmits to when the receiving means 7 receives. The liquid amount calculating means 9 calculates the liquid amount from the time measured by the time measuring means 8. The liquid amount display means 10 is constituted by an LED, and displays the liquid amount calculated by the liquid amount calculation means. 11
Is a water supply notifying means for notifying that the liquid amount in the container 1 is less than a predetermined value, and is constituted by a resistor 11a and an LED 11b. 1
Numeral 2 is a full-water notifying means for notifying that the liquid amount in the container 1 has exceeded a predetermined value, and comprises a resistor 12a and an LED 12b. Reference numeral 13 denotes boiling notification means, which comprises a resistor 13a and an LED 13b. The control means 14 outputs on / off signals to the relay coil 5b, the water supply notification means 11, the full water notification means 12, and the boiling notification means 13 based on the time measured by the clock measurement means 8. 15 is a commercial power supply.

Next, the operation will be described. When water is put into the container 1 and a commercial power supply 15 is applied, a high frequency signal a as shown in FIG. 3A is applied to the ultrasonic sensor 4 by the transmitting means 6, and the ultrasonic sensor 4 generates an ultrasonic wave. An ultrasonic wave is output into the water through the container 1. The ultrasonic waves are reflected by the water surface 3 and become reflected waves. The ultrasonic sensor 4 detects the reflected wave and outputs a reflected wave signal b as shown in FIG. here,
The time T (s) from when the ultrasonic sensor 4 outputs the ultrasonic wave to when the first reflected wave is detected is T = 2 ×, where the distance between the water surface 3 and the ultrasonic sensor 4 is H (cm). H / V. V
Is the speed of sound, which is 1.5 × 10 ⁵ (cm / s). The reason why the reflected wave signal b is periodically generated while being attenuated is that the reflection is repeated at the water surface 3 and the bottom of the container 1. The receiving unit 7 amplifies the reflected wave signal b of the ultrasonic sensor, shapes the waveform, and outputs the amplified signal to the time measuring unit 8, and the time measuring unit 8 measures T. Here, assuming that the pi is π and the inner diameter of the container 1 is D (cm), the liquid amount L () is L = [πD ² · VT / 8] × 10 ^-3 . If the liquid amount for detecting the water supply is L1 () and the liquid amount for detecting the full water is L2 (), the first set time T1 corresponding to L1 is T1 = 8 × (L1) × 10 ³ / (ΠD ² V) and L
The second set time T2 corresponding to 2 is T2 = 8 × (L2) × 10 ³
/ (ΠD ² V). For example, D = 15cm, L1 = 0.3, L
If 2 = 3, T1 = 23 μs and T2 = 226 μs. Assuming that the liquid amount is between L1 and L2, the time T measured by the time measuring means 8 is also between the first set time T1 and the second set time T2.

FIG. 4 shows a flowchart of the operation. In FIG. 4, when the liquid amount is between L1 and L2, NO is determined in step 21 and YES is determined in step 22, and in step 23, the liquid amount calculating means 9 outputs the calculation result to the liquid amount displaying means 10, and At 24, the liquid amount display means 10 displays the liquid amount (in the embodiment, up to one decimal place in liters), and at step 25, the control means 14
Outputs an ON signal to 5b. As a result, the relay contact 5a is closed, and the heating means 2 starts heating.

Here, when the water in the container 1 is used, or when the amount of water is small from the beginning and the liquid amount does not reach L1, T becomes less than the first set time T1, and since step 21 is YES, step Proceeding to 26, the control means 14 outputs an OFF signal to the relay coil 5b, the relay contact 5a opens, the heating of the heating means 2 is stopped, and in step 27, the control means 14 outputs an ON signal to the water supply notification means 11. Then, the LED 11b of the water supply detecting means 11 lights up to notify that the water level is low.

On the other hand, when water is added to the container 1 or when the amount of water is large from the beginning and the amount of liquid exceeds L2, T exceeds the second set time T2, and step 21 is NO, so step twenty two
And the step 22 becomes NO, and the process proceeds to a step 28. Note that the third set time T3 is set to a value that is impossible when water is put into the container 1. Here, set to 4 and 302μ
s. Then, since step 28 is YES, step 2
At 9, the control means 14 outputs an off signal to the relay coil 5b,
The relay contact 5a is opened and the heating of the heating means 2 is stopped, and in step 30, the control means 14 outputs an ON signal to the full-water notification means 12, and the LED 12b of the full-water detection means 12 is turned on to notify that water is excessively filled.

By the way, when the liquid amount is between L1 and 2, the relay contact 5a is closed in step 25 and the water in the container 1 is heated by the heating means 2 as described above. When the water temperature in the container 1 rises and reaches the boiling point, the water surface 3 shakes with the generation of air bubbles, the ultrasonic waves are irregularly reflected by the air bubbles, and the reflection on the water surface 3 becomes unstable, and the ultrasonic sensor 4 detects the reflected wave. No longer.
As a result, step 21 is NO, step 22 is NO, step
28 is NO, and the process proceeds to Step 31. In step 31, the control means 14 outputs an off signal to the relay coil 5b,
5a opens and the heating means 2 stops heating. In step 32, the control means 14 outputs an ON signal to the boiling notification means 13,
The LED 13b lights up to indicate that it has boiled.

Effect of the Invention As described above, according to the present invention, the ultrasonic wave is converted into a liquid amount by measuring the time when the underwater velocity is determined and reflected on the water surface and returned, so that the liquid amount can be accurately calculated. Can be displayed.

Further, by comparing the measured time with the first set time, when the liquid amount is smaller than the predetermined amount, the user can be notified by the water supply notifying means.

Also, by comparing the measured time with the second set time, if the liquid amount exceeds the predetermined amount and the water is heated as it is, when the hot water overflows at the time of boiling and there is a danger of burns,
The user can be notified by the full-water notification means, and danger can be prevented beforehand.

Further, the measured time is set to a third time longer than the second set time.
By comparing with the set time, it is possible to determine whether or not boiling is occurring, and it is possible to detect boiling without a time delay.

And these detections do not require multiple sensors,
This can be realized with only one ultrasonic sensor.

[Brief description of the drawings]

1 is a partially cutaway side view of an electric water heater according to one embodiment of the present invention, FIG. 2 is a circuit diagram of the electric water heater, FIG. 3 is a waveform diagram of each part, and FIG. 4 is an operation of the electric water heater. The flowchart shown in FIG. 5 is a partial perspective view of a conventional electric water heater. 1 ... container, 2 ... heating means, 4 ... ultrasonic sensor, 5
... energization control means, 6 ... transmission means, 7 ... reception means,
8 time measuring means 9 liquid amount calculating means 10 liquid amount displaying means 11 water supply informing means 12 full water informing means
13 ... boiling notification means, 14 ... control means.

Continuation of the front page (72) Inventor Kenji Noda 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Microfilm photographing the contents of the specification and drawings attached to (Japanese Patent Application No. 63-35371 (Japanese Utility Model Application No. 1-138322)). Film (JP, U)

Claims (3)

(57) [Claims] 1. A container for accommodating a liquid, a heating unit for heating the liquid in the container, an energization control unit for controlling the energization of the heating unit, an ultrasonic sensor installed at the bottom of the container, and an ultrasonic sensor Transmitting means for transmitting an outgoing signal, receiving means for receiving a signal from the ultrasonic sensor, and time measuring means for measuring the time from when the transmitting means transmits to when the receiving means receives the signal. If the measured value of the means is less than the first set time, an electric water heater that outputs an off signal to the energization control means and stops the heating means. 2. A container for accommodating a liquid, a heating unit for heating the liquid in the container, an energization control unit for controlling the energization of the heating unit, an ultrasonic sensor installed at the bottom of the container, and an ultrasonic sensor. Transmitting means for transmitting an outgoing signal, receiving means for receiving a signal from the ultrasonic sensor, and time measuring means for measuring the time from when the transmitting means transmits to when the receiving means receives the signal. If the measured value of the means exceeds the second set time, an off signal is output to the energization control means,
An electric water heater that stops the heating means. 3. A container for accommodating a liquid, a heating unit for heating the liquid in the container, an energization control unit for controlling the energization of the heating unit, an ultrasonic sensor installed at the bottom of the container, and an ultrasonic sensor. Transmitting means for transmitting a transmission signal to the receiving means, receiving means for receiving a signal from the ultrasonic sensor, and time measuring means for measuring the time from transmission of the transmitting means to reception of the receiving means, the receiving means An electric water heater that stops heating means when it no longer detects reflected waves.