Dry burning prevention detection circuit
By using a metal probe to detect resistance in the inner tank of the electric water heater and combining it with pulse current detection, the problem of inconsistent temperature sensor thresholds in the anti-dry-burning function of the electric water heater is solved. This achieves high-precision water shortage detection and circuit simplification, avoids dry burning, and extends the service life of the heater.
Patent Information
- Application Number
- CN202520039976.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-07
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2035-01-07
AI Technical Summary
The existing anti-dry-burning function of electric water heaters has the problem of inconsistent temperature sensor thresholds, resulting in inconsistent temperatures when the power is off, and thus failing to effectively prevent dry burning.
Two metal probes are used to detect whether there is water in the inner tank of the electric water heater. The resistance between the probes is used to determine whether there is water. Combined with pulse current detection, the heating is automatically stopped to avoid dry burning.
It achieves high-precision water shortage detection, avoids dry burning of electric water heaters, extends heater life, reduces costs and simplifies circuit design.
Smart Images
Figure CN223581128U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to detection circuit technical field, concretely relates to a kind of dry burning detection circuit. BACKGROUND
[0002] With the development of economic society, people's living standards continue to improve, people's demand for hot water is more and more common, electric water heater is the household appliance commonly used in people's daily life.Heater as the key component of electric water heater, its quality problem will directly affect the life of electric water heater, and dry burning is the most important reason for causing quality problems of electric water heater, and the quality problem caused by dry burning is generally not a small problem, generally heater is damaged in dry burning state for several minutes, so ensure that inner container does not work in no water state, it is the primary condition to avoid dry burning of heater.Currently, the dry burning prevention function of electric water heater is mainly realized by temperature sensor and bimetallic strip.Temperature sensor is used to detect water temperature in real time, and when water temperature reaches a certain threshold, power supply is automatically cut off to prevent dry burning.But since bimetallic strip controls the opening and closing of power supply according to physical deformation, it leads to poor consistency of threshold and inconsistent temperature of power-off. SUMMARY
[0003] In order to solve the problems of prior art, the utility model provides a dry burning detection circuit with simple circuit, few electronic components, low cost and high detection precision, which detects whether there is water in water heater through pulse current, and automatically stops working in water shortage state, thereby avoiding dry burning phenomenon of water heater and prolonging service life of heater.
[0004] The utility model employs the following technical scheme: a dry burning detection circuit, comprising two metal probes, the metal probes are arranged in the inner container of water heater, whether there is water to immerse the metal probe is judged by detecting the resistance value between the two metal probes, resistance R50 and R46 are sequentially connected with capacitor D4, metal probe two, one end of resistance R47 is connected with pulse input port SW-F, the other end is connected with resistance R46 and capacitor C14 at first common connection port, resistance R50 is connected with MCU signal of water heater control panel, filter circuit is connected between resistance R50 and capacitor C14, resistance R45 is connected with capacitor C14 in parallel, and metal probe one is connected with resistance R53 and grounded.
[0005] The P end of diode D4 is connected with resistance R45 and first common connection port, the N end of diode D4 is connected with metal probe two, the N end of diode D3 and the N end of diode D4 are connected in common, and the P end of diode D3 is grounded.
[0006] The filter circuit comprises capacitor C15 and resistance R48 connected in parallel, one end of the filter circuit is connected between resistance R50 and resistance R46, and the other end is grounded.
[0007] Preferably, the SW-F port outputs a pulse voltage to the pulse input port SW-F every X minutes, and the use of the pulse voltage can avoid the electrochemical polarization phenomenon of the metal probe.
[0008] The utility model discloses the beneficial effects are:
[0009] The circuit of the utility model is simple and reasonable in design, the components used are also less, cost can be saved, and the water shortage state can be detected in time when the water heater is short of water, the water heater is stopped heating, and dry burning of the water heater is avoided. BRIEF DESCRIPTION OF DRAWINGS
[0010] Figure 1 It is the water shortage detection principle diagram for water heater;
[0011] Figure 2 It is the SW-F port pulse output change graph with time; DETAILED DESCRIPTION
[0012] The embodiments of the utility model are described in detail below, and the examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the utility model, and cannot be understood as limiting the utility model.
[0013] In the description of the utility model, it is necessary to explain that, unless there is explicit provision and limitation, the terms "mounting", "connection" and "connection" should be understood broadly, for example, it can be fixed connection. It can also be detachable connection, or integrally connected, it can be mechanical connection, or electrical connection, it can be directly connected, or indirectly connected through intermediate medium, it can be the communication inside two elements. For ordinary skilled in the art, the above-mentioned terms can be understood as the specific meaning of the utility model.
[0014] Reference Figure 1 A dry burning prevention detection circuit, comprising two metal probes, the metal probes are arranged in the inner container of the water heater, whether the metal probes are immersed in water is judged by detecting the resistance value between the two metal probes, resistance R50 and R46 are sequentially connected with capacitor D4 and metal probe two, one end of resistance R47 is connected with pulse input port SW-F, the other end is connected with resistance R46 and capacitor C14 in the first common connection port, resistance R50 is connected with VOL port of the control panel of the water heater, a filter circuit is connected between resistance R50 and capacitor C14, resistance R45 is connected with capacitor C14 in parallel, and metal probe one is connected with resistance R53 and grounded.
[0015] Figure 1In the figure, CN1 represents a metal probe, wherein, the number 1 represents a port connected with the metal probe one, and the number 2 represents a port connected with the metal probe two. For the detection port between the two metal probes, the voltage value of the VOL end of the resistance R50 is more stable after the filtering circuit, and the detection of whether the two probes in the inner container of the water heater are submerged in water is more accurate.
[0016] The P end of the diode D4 is connected with the resistance R45 and the first common port, the N end of the diode D4 is connected with the metal probe two, the N end of the diode D3 and the N end of the diode D4 are commonly connected, and the P end of the diode D3 is grounded.
[0017] The filtering circuit comprises the capacitor C15 and the resistance R48 which are connected in parallel, one end of the filtering circuit is connected between the resistance R50 and the resistance R46, and the other end is grounded.
[0018] Preferably, the diodes D3 and D4 are both rectifier diodes 1N4007, the resistances R50 and R53 are 0 ohm resistances, the resistance R47 has a resistance value of 50K Ω, the resistance R46 has a resistance value of 1K Ω, the resistance R45 has a resistance value of 1M Ω, and the capacitor C14 has a capacity of 1 μF.
[0019] With reference to Figure 2 The SW-F port sends out a pulse every 1 second, and the utility model does not continuously provide a 5V voltage input, but selects to provide a pulse in a timing manner, so that the phenomenon of metal probe electrochemistry caused by continuous voltage can be prevented.
[0020] Although the embodiments of the utility model have been shown and described, those skilled in the art should understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the utility model, the scope of the utility model is defined by the claims and its equivalent replacements, and the improvements and the like without creative labor should be included in the protection scope of the utility model.
Claims
1. A dry-burn detection circuit comprising two metal probes, the metal probes being disposed in a water heater inner tank, and the dry-burn detection circuit being configured to determine whether the metal probes are submerged in water by detecting a resistance between the two metal probes, characterized in that: The resistance R50 and R46 are connected with the capacitor D4 and the metal probe two in sequence, one end of the resistance R47 is connected with the pulse input port SW-F, the other end is connected with the resistance R46 and the capacitor C14 in the first common connection port, the resistance R50 is connected with the MCU signal of the water heater control panel, the filter circuit is connected between the resistance R50 and the capacitor C14, the resistance R45 is connected with the capacitor C14 in parallel, and the metal probe one is connected with the resistance R53 and grounded.
2. The dry-burn detection circuit of claim 1, wherein: The P end of the diode D4 is connected with the resistance R45 and the first common connection port, the N end of the diode D4 is connected with the metal probe two, the N end of the diode D3 and the N end of the diode D4 are connected in common, and the P end of the diode D3 is grounded.
3. A dry-burn detection circuit according to claim 1 or 2, characterised in that: The filter circuit comprises the capacitor C15 and the resistance R48 connected in parallel, one end of the filter circuit is connected between the resistance R50 and the resistance R46, and the other end is grounded.
4. The dry-burn detection circuit of claim 3, wherein: The resistance value of the resistance R47 is set in the range of 10K-60KΩ, the resistance value of the resistance R45 is set in the range of 5M-10MΩ, and the capacity of the capacitor C15 is set in the range of 0.1μF-10μF.
5. The dry-burn detection circuit of claim 4, wherein: The resistance value of the resistance R47 is 50K, the resistance value of the resistance R45 is 10MΩ, and the capacity of the capacitor C15 is 10μF.
6. The dry-burn detection circuit of claim 1 or 2, wherein: The water heater control panel controls the power supply circuit to output the pulse voltage to the pulse input port SW-F every interval X minutes.