JPH01227020A - Detecting device of water level of electric pot - Google Patents

Abstract

PURPOSE:To enable the stable detection of a water level even when hot water is in service, by providing an ultrasonic element in the bottom part of a vessel and by determining the water level from the time of propagation required for an ultrasonic wave to be reflected on a water surface of the vessel and returned. CONSTITUTION:An ultrasonic element 3 is fitted to the bottom part of a vessel 1 and a prescribed water level detecting circuit is connected thereto. A water level of the vessel 1 is detected from the time of propagation required for an ultrasonic wave emitted from the ultrasonic element 3 to be reflected on a water surface of the vessel 1 and returned to the ultrasonic element 3. The ultrasonic element is usually provided in the bottom of a water indicator tube 12 prepared by forming a part of a water service pipe of a glass tube, and in this case, detection turns impossible after the water surface for reflection disappears temporarily when the indicator tube 12 is filled up with hot water. The present invention solves this problem, enabling the stable detection of the water level even when the hot water is in service.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a water level detection device for an electric kettle.

Conventional technology A conventional water level detection device for an electric kettle uses a water level display tube made of a transparent material such as glass, which is a part of a hot water tap that communicates with the bottom of a bottomed cylindrical container and extends upward, to visually check the water level from the outside. In order to improve visibility, these water display tubes were designed with a float inside them, and a pattern on the back of the tube that changes shape when turned.

Furthermore, in recent years, a method of measuring the water level using reflection of ultrasonic waves has been considered. In this method, as shown in FIG. 3, an ultrasonic element 3 is provided at the bottom of the water volume indicator 12 constituting the hot water tap pipe, and its radiation surface is exposed in the water. The ultrasonic waves emitted into the water propagate into the water, are totally reflected on the water surface 2, and return to the original ultrasonic element 3. The time it takes for the ultrasonic waves to propagate and return is because the propagation speed of ultrasonic waves in water is approximately constant at approximately 1500 m/see.
The time required is proportional to the water level. By measuring the time from when this ultrasonic wave is emitted until it returns, it is possible to accurately determine the water level.

Problems to be Solved by the Invention The conventional water level display tube described above has the disadvantage that it is difficult to see unless it is in a bright place, and a drop in the water level is often not noticed.

Additionally, products that use ultrasonic elements can accurately detect and control the water level, but they require a separate display element, such as an LED, to display the water level to the user, making it difficult to check from the outside. There was still a problem. In addition, the entire inside of the water display tube 12 may be filled with hot water, and the water surface 2 on which the ultrasonic waves are reflected may temporarily disappear, making accurate detection impossible. Since the water level 2 in the display tube 12 rises and falls rapidly, the LED
There are many inconveniences, such as the display moving up and down.

Means for Solving the Problems The present invention has been made in order to solve the above-mentioned problems, and includes an ultrasonic element that emits an ultrasonic wave upward on the bottom of a container, and an ultrasonic wave emitted from this ultrasonic element. The water level in the container is detected by determining the propagation time for the ultrasonic wave to reflect on the water surface inside the container and return to the ultrasonic element.

Function With the above configuration, the ultrasonic element provided at the bottom of the container and the water level detection means connected to the ultrasonic element emit ultrasonic waves from the bottom of the container in a substantially vertical direction, and the ultrasonic waves are transmitted into the container. It receives ultrasonic waves that propagate through water, reflect on the water surface, and return to the ultrasonic element, and detects a stable water level based on the time it takes for the ultrasonic waves to travel back and forth.

Embodiment FIG. 1 is a sectional view of essential parts of an electric kettle incorporating an embodiment of the water level detection means of the present invention, and FIG. 2 is a block circuit diagram thereof.

1 is a cylindrical container with a bottom that stores water; 2 is a water surface representing the water level in the container 1; 3 is a device provided at the bottom of the container 1 that radiates ultrasonic waves toward the water surface 2 and collects reflected waves from the water surface 2. 4 is an amplifier, 5 is an ultrasonic generator that generates ultrasonic waves of approximately 2 MHz, 6 is a timing pulse generator that generates pulses with a constant period, and 7 is an 8 is a pulse input unit that combines the pulses from the waveform shaping unit 7 and the timing pulse generator 6; 9 is a microcomputer that controls the operation of the electric pot; and 9 is a microcomputer that controls the operation of the electric kettle. The means 10 is composed of an amplifier 4 or a microcomputer 9. Reference numeral 11 denotes a heating element, which is in contact with the bottomed cylindrical container 1 that stores water.

Reference numeral 12 designates a water quantity display tube formed of a glass tube as a part of a tap water pipe that communicates with the bottom of the container 1 and extends upward, and reference numeral 13 designates an indicator consisting of an LED.

The operation of this embodiment having the above configuration will be explained.

The ultrasonic waves generated by the ultrasonic generator 5 are input to the ultrasonic element 3 via the amplifier 4, and are emitted toward the water surface 2. The emitted ultrasonic wave propagates upward through the water inside the container 1, is totally reflected when it reaches the water surface 2, and is reflected again by the ultrasonic element 3.
Returning to the original position, the ultrasonic element 3 is vibrated to generate an ultrasonic signal. This incoming ultrasonic signal is amplified by an amplifier 4 and converted into a pulse through a waveform shaping section 7. This pulse and the pulse from the timing pulse generator 6 are synthesized by the pulse input section 8 and the resulting value is input to the microcomputer 9. This value has information on the time difference between the ultrasonic wave and the time it is emitted by the ultrasonic element 3 until it returns, and if the water level 2 changes, the propagation time will also change proportionally, so the water level detection means 10 Water level can be detected. Microcomputer 9
This water level data is displayed on the indicator 13, and control is performed such as energizing the plow heating element 11 in response to an operation command, or stopping energizing the heating element 11 when the water level becomes lower than a predetermined water level.

According to this method, even when hot water is filled from the entire tap pipe to the sprue when hot water is tapped, the water surface 2 in the container 1 is always present, so ultrasonic waves can be reflected accurately and a stable water level can be displayed. can.

Effects of the Invention According to the present invention, an ultrasonic element that emits ultrasonic waves upward is provided at the bottom of the container, a water level detection means is connected to this ultrasonic element, and the ultrasonic waves are reflected on the water surface inside the container. Since the water level is detected by adjusting the water level, it is possible to accurately detect a stable water level even when hot water is being tapped.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of a water level detection device for an electric kettle showing one embodiment of the present invention, FIG. 2 is a block circuit diagram thereof, and FIG.
The figure is a sectional view of a main part of a conventional water level detection device for an electric kettle. 1... Container, 3... Ultrasonic element, 10...
・Water level detection means.

Claims (1)

[Claims] An ultrasonic element (3) that emits ultrasonic waves upward is provided on the bottom of a bottomed cylindrical container (1) that stores water, and a water level detection means (10) is connected to this ultrasonic element (3). The water level in the container (1) is determined by the propagation time for the ultrasonic waves emitted from the ultrasonic element (3) to propagate through the water in the container (1), reflect on the water surface, and return to the ultrasonic element (3). A water level detection device for an electric pot characterized by detection and control.