Timing control circuit for oven

Abstract

The utility model provides a timing control circuit for an oven, which relates to the technical field of timing control circuits and comprises a power supply module, a control chip, an electromagnetic switch, a temperature compensation module and a control module, one end of the temperature compensation module is connected with the power supply module, and the other end of the temperature compensation module is grounded. Comprising a thermistor, a variable resistor and a capacitor which are connected in series, the control module comprises a first switch part, the first switch part is connected to a power supply loop of the electromagnetic switch in series, and the control chip is electrically connected with the first switch part used for controlling on-off of the power supply loop of the electromagnetic switch. The thermistor is used for sensing environment temperature changes, dynamically adjusting the total resistance value of the RC network, controlling capacitor discharge time, shortening heating time in a high-temperature environment and prolonging heating time in a low-temperature environment, so that the baking effect is kept consistent under a fixed gear, the structure is simple, and the cost is low.

Description

Technical Field

[0001] This utility model relates to the field of timing control circuit technology, and in particular to a timing control circuit for an oven. Background Technology

[0002] Currently, the timing function of ovens on the market is implemented in the following two main ways:

[0003] 1. Using a mechanical knob and spring mechanism to control the heating time via mechanical timing. This method is low-cost and simple in structure, but the time control accuracy is poor and it is easily affected by mechanical wear, leading to increased timing errors.

[0004] 2. Timing control is typically achieved using a general-purpose timing IC (such as a 555 timer) or an MCU (microcontroller) in conjunction with peripheral circuits. This method offers high precision and flexibility, but requires more external components, resulting in higher hardware costs. Furthermore, MCU solutions require additional program development, leading to greater design complexity.

[0005] Furthermore, existing oven timer functions generally lack adaptability to changes in ambient temperature. Different ambient temperatures affect baking results, and existing ovens cannot dynamically adjust heating time according to ambient temperature. This is especially problematic in northern regions, where baking results differ significantly between summer and winter, even under the same operating mode. Utility Model Content

[0006] To overcome the shortcomings of the prior art, the technical problem to be solved by this utility model is to propose a timer control circuit for an oven, and the following technical solution is adopted:

[0007] A timer control circuit for an oven includes a power supply module, a control chip, and an electromagnetic switch. The power supply module supplies power to the control chip and the electromagnetic switch.

[0008] The temperature compensation module includes a thermistor, a variable resistor, and a capacitor connected in series. The thermistor has a negative temperature coefficient, and one end of the capacitor is grounded while the other end is electrically connected to the control chip.

[0009] The control module includes a first switch element connected in series in the power supply circuit of the electromagnetic switch, and a control chip electrically connected to the first switch element for controlling the on and off states of the power supply circuit of the electromagnetic switch.

[0010] As a further improvement, the control module also includes a push-button switch and a second switch. The second switch is an NPN transistor, with the push-button switch connected between its base and emitter. The collector and emitter are connected to the power supply circuit of the electromagnetic switch, and the control chip is connected between the base and the push-button switch.

[0011] As a further improvement, the first switching element is an NPN transistor, with its base connected to the control chip, its collector connected to the power supply module, and its emitter connected to the collector of the second switching element.

[0012] As a further improvement, the base of the first switching element is connected in series with an eighth bias resistor, and the base of the second switching element is connected in series with a ninth bias resistor.

[0013] As a further improvement, the resistance of the variable resistor is adjusted by a knob. The knob is equipped with a baffle. When the variable resistor is adjusted to its minimum resistance, the baffle presses the button switch to turn it on.

[0014] As a further improvement, a freewheeling diode is connected in parallel across the two ends of the electromagnetic switch.

[0015] As a further improvement, a fifth voltage-dividing resistor is connected in parallel across the variable resistor; a sixth voltage-dividing resistor is connected in parallel across the thermistor; and a fourth voltage-dividing resistor is connected in series between the variable resistor and the capacitor.

[0016] As a further improvement, the power supply module includes a voltage input terminal, which forms a first output terminal through a rectifier diode and a resistor network. The first output terminal is connected to the electromagnetic switch. The first output terminal forms a second output terminal through a voltage stabilizing filter network. The second output terminal supplies power to the control chip and the temperature compensation module.

[0017] As a further improvement, the aforementioned voltage regulator and filter network includes a second voltage divider resistor and a seventh voltage divider resistor connected in series. The second output terminal is located between the second voltage divider resistor and the seventh voltage divider resistor. A filter capacitor is connected in parallel with the second voltage divider resistor, and a Zener diode is connected in parallel between the second output terminal and ground.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] Firstly, this invention introduces a thermistor and an RC network. The thermistor senses changes in ambient temperature and dynamically adjusts the total resistance of the RC network, thereby controlling the discharge time of capacitor C4. This structure solves the problem of inconsistent baking results in ovens due to changes in ambient temperature. It shortens the heating time in high-temperature environments and extends the heating time in low-temperature environments, ensuring consistent baking results under the same mode (or fixed setting). The structure is simple and low-cost.

[0020] Secondly, the control module of this utility model includes a first switch, a second switch, and a push-button switch. Timing adjustment is achieved by adjusting a variable resistor. Upon power-up, the power supply module supplies power to the temperature compensation module, and capacitor C4 charges. When capacitor C4 reaches a predetermined voltage, the control chip outputs a low-level signal to the base of the first and second switches to cut them off, thus disconnecting the power supply branch to the electromagnetic switch. This structure is simple and efficient, and the chip technology for implementing this function is mature and inexpensive.

[0021] Thirdly, in this utility model, the variable resistor is controlled by a knob. When the variable resistor is adjusted to the minimum, the knob's baffle touches and presses the button switch, turning off the button switch and cutting off the second switching component. Even if the electromagnetic switch is disconnected, the heating is quickly and safely cut off. As a manual control stop and emergency termination function, it improves the safety and convenience of operation. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the circuit structure of this utility model;

[0024] Figure 2 This is a schematic diagram showing the position and structure of the knob and push-button switch in this utility model.

[0025] Figure label:

[0026] 1-Power supply module; 2-Temperature compensation module; 3-Control module; 41-Knob; 411-Baffle;

[0027] IC - Control chip; L1 - Electromagnetic switch; NTC - Thermistor; VR - Variable resistor;

[0028] Q1 - First switching element; Q2 - Second switching element; S1 - Push button switch;

[0029] R2 - Second voltage divider resistor; R4 - Fourth voltage divider resistor; R5 - Fifth voltage divider resistor; R6 - Sixth voltage divider resistor; R7 - Seventh voltage divider resistor; R8 - Eighth bias resistor; R9 - Ninth bias resistor;

[0030] D3 - Freewheeling diode; D1 - Rectifier diode; DZ - Zener diode;

[0031] C1 - Filter capacitor; C4 - Capacitor. Detailed Implementation

[0032] To facilitate understanding by those skilled in the art, the structure of this utility model will now be described in further detail with reference to the accompanying drawings:

[0033] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. The terms "part," "side," "end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this utility model.

[0034] like Figure 1 As shown, this application provides a timer control circuit for an oven, including a power supply module 1, a control chip IC, and an electromagnetic switch L1. The power supply module 1 supplies power to the control chip IC and the electromagnetic switch L1.

[0035] The power supply module includes a voltage input terminal, which forms a first output terminal through a rectifier diode D1 and a resistor network. The voltage at the first output terminal is as follows: Figure 1 The first output terminal of VDD shown is connected to electromagnetic switch L1; the first output terminal is connected to a voltage regulator and filter network to form the second output terminal, and the voltage of the second output terminal is as shown. Figure 1 The VCC shown is used to power the control chip IC and the temperature compensation module 2.

[0036] Preferably, the resistor network is formed by connecting two resistor branches, each with a 150Ω resistor connected in series, in parallel.

[0037] The voltage regulator and filter network includes a second voltage divider resistor R2 and a seventh voltage divider resistor R7 connected in series. The second output terminal is located between the second voltage divider resistor R2 and the seventh voltage divider resistor R7. A filter capacitor C1 is connected in parallel with the second voltage divider resistor R2, and a Zener diode DZ is connected in parallel between the second output terminal and ground. Preferably, the resistance of the second voltage divider resistor R2 is 3KΩ, the capacitance of the filter capacitor C1 is 47µF, the rated operating voltage is 35V, the Zener diode DZ has a Zener voltage of 4.7V, the resistance of the seventh voltage divider resistor R7 is 2.2KΩ, and the output voltage VCC of the second output terminal is 4.2~5.2V.

[0038] In one specific embodiment, the electromagnetic switch L1 serves as the on / off switch for the oven heating assembly (not shown in the figure). The on / off duration of the electromagnetic switch L1 is equivalent to the heating duration of the oven. The control chip IC is a toaster-specific chip, which has the basic functions of detecting voltage or current signals and issuing control signals.

[0039] Furthermore, such as Figure 1 As shown, it also includes a temperature compensation module 2 and a control module 3. The temperature compensation module 2 includes a thermistor NTC, a variable resistor VR, and a capacitor C4 connected in series. The thermistor NTC has a negative temperature coefficient. One end of the capacitor C4 is grounded, and the other end is electrically connected to the control chip IC. The thermistor NTC is used to detect the ambient temperature. When the ambient temperature is high, the resistance of the thermistor NTC decreases, the total resistance of the charging branch decreases, and the charging time of capacitor C4 to the preset voltage is shorter. When the ambient temperature is low, the resistance of the thermistor NTC increases, the total resistance of the charging branch increases, and the charging time of capacitor C4 to the preset voltage is longer.

[0040] Preferably, the thermistor NTC has a normal resistance of 150KΩ, the variable resistor VR has a maximum resistance of 250KΩ, a fifth voltage divider resistor R5 with a resistance of 330KΩ is connected in parallel across the variable resistor VR, a sixth voltage divider resistor R6 with a resistance of 273KΩ is connected in parallel across the thermistor NTC, and a fourth voltage divider resistor R4 with a resistance of 10KΩ is connected in series between the variable resistor VR and the capacitor C4.

[0041] like Figure 1 As shown, on the other hand, the control module 3 includes a first switch Q1, which is connected in series in the power supply circuit of the electromagnetic switch L1. The control chip IC is electrically connected to the first switch Q1 and is used to control the conduction and disconnection of the power supply circuit of the electromagnetic switch L1. Specifically, when powered on, the control chip IC controls the first switch Q1 to conduct, and the power supply module 1 supplies power to the electromagnetic switch L1. When the voltage across the capacitor C4 reaches a preset value, that is, when the control chip IC detects that the voltage across the capacitor C4 has reached the preset value, it controls the first switch Q1 to disconnect, thereby cutting off the power supply circuit of the electromagnetic switch L1. By combining the above-mentioned thermistor detection of ambient temperature and dynamically adjusting the charging time of capacitor C4, the start-up time of the electromagnetic switch L1, i.e., the heating time of the oven, is increased or decreased. This solves the problem of inconsistent baking effect caused by changes in ambient temperature. The heating time is shortened in high-temperature environments (such as summer) and extended in low-temperature environments (such as winter), so that the baking effect remains consistent under the same mode (or fixed setting). This structure is simple and low-cost.

[0042] like Figure 1 As shown, the control module 3 also includes a push-button switch S1 and a second switch Q2. The second switch Q2 is an NPN transistor, with the push-button switch S1 connected between its base and emitter. Its collector and emitter are connected to the power supply circuit of the electromagnetic switch L1. The control chip IC is connected between the base and the push-button switch S1. When the push-button switch S1 is turned on, the second switch Q2 is turned off because its base is grounded, thereby cutting off the power supply branch of the electromagnetic switch L1.

[0043] exist Figure 1Based on the combination Figure 2 In one specific embodiment, the variable resistor VR is a potentiometer, and its resistance value is controlled and adjusted by a knob 41. The knob 41 is equipped with a baffle 411. When the variable resistor VR is adjusted to its minimum resistance, the baffle 411 presses the push-button switch S1 to turn it on. In this embodiment, the user can manually turn off the oven heating, combining manual heating shutdown with timer setting via the knob, thus improving operational safety and convenience.

[0044] like Figure 1 As shown, in one specific embodiment, the first switching element Q1 is an NPN transistor, with its base connected to the control chip IC, its collector connected to the power supply module 1, and its emitter connected to the collector of the second switching element Q2. Pin 1 of the control chip IC is a control pin, and pin 4 is a detection pin. When pin 4 detects that the voltage of capacitor C4 exceeds a preset value, pin 1 switches from high to low. At this time, the first switching element Q1 is cut off due to its base becoming low, meaning the power supply circuit of the electromagnetic switch L1 is cut off, and the oven stops heating. Preferably, an eighth bias resistor R8 is connected in series with the base of the first switching element Q1, and a ninth bias resistor R9 is connected in series with the base of the second switching element Q2.

[0045] Furthermore, as a preferred embodiment, the eighth bias resistor R8 has a resistance of 10KΩ, the ninth bias resistor R9 has a resistance of 10KΩ, and a freewheeling diode D3 is connected in parallel across the electromagnetic switch L1.

[0046] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A timer control circuit for an oven, comprising a power supply module (1), a control chip (IC), and an electromagnetic switch (L1), wherein the power supply module (1) supplies power to the control chip (IC) and the electromagnetic switch (L1), characterized in that: Also includes The temperature compensation module (2) includes a thermistor (NTC), a variable resistor (VR), and a capacitor (C4) connected in series. The thermistor (NTC) has a negative temperature coefficient, and one end of the capacitor (C4) is grounded and the other end is electrically connected to the control chip (IC). The control module (3) includes a first switch (Q1), which is connected in series in the power supply circuit of the electromagnetic switch (L1). The control chip (IC) is electrically connected to the first switch (Q1) and is used to control the conduction and disconnection of the power supply circuit of the electromagnetic switch (L1).

2. The timer control circuit for an oven as described in claim 1, characterized in that: The control module (3) further includes a push button switch (S1) and a second switch (Q2). The second switch (Q2) is an NPN transistor, with the push button switch (S1) connected between its base and emitter. Its collector and emitter are connected to the power supply circuit of the electromagnetic switch (L1), and the control chip (IC) is connected between the base and the push button switch (S1).

3. A timer control circuit for an oven as described in claim 2, characterized in that: The first switching device (Q1) is an NPN transistor, with its base connected to the control chip (IC), its collector connected to the power supply module (1), and its emitter connected to the collector of the second switching device (Q2).

4. A timer control circuit for an oven as described in claim 3, characterized in that: The base of the first switching element (Q1) is connected in series with an eighth bias resistor (R8), and the base of the second switching element (Q2) is connected in series with a ninth bias resistor (R9).

5. A timer control circuit for an oven as described in claim 2, characterized in that: The variable resistor (VR) has its resistance value adjusted by a knob (41). The knob (41) is equipped with a baffle (411). When the variable resistor (VR) is adjusted to its minimum resistance, the baffle (411) presses the push button switch (S1) to turn it on.

6. A timer control circuit for an oven as described in claim 1, characterized in that: A freewheeling diode (D3) is connected in parallel across the two ends of the electromagnetic switch (L1).

7. A timer control circuit for an oven as described in claim 1, characterized in that: A fifth voltage divider resistor (R5) is connected in parallel across the variable resistor (VR); a sixth voltage divider resistor (R6) is connected in parallel across the thermistor (NTC); and a fourth voltage divider resistor (R4) is connected in series between the variable resistor (VR) and the capacitor (C4).

8. A timer control circuit for an oven as described in claim 1, characterized in that: The power supply module includes a voltage input terminal, which forms a first output terminal through a rectifier diode (D1) and a resistor network. The first output terminal is connected to the electromagnetic switch (L1). The first output terminal forms a second output terminal through a voltage stabilizing filter network. The second output terminal supplies power to the control chip (IC) and the temperature compensation module (2).

9. A timer control circuit for an oven as described in claim 8, characterized in that: The voltage regulator filter network includes a second voltage divider resistor (R2) and a seventh voltage divider resistor (R7) connected in series. The second output terminal is located between the second voltage divider resistor (R2) and the seventh voltage divider resistor (R7). A filter capacitor (C1) is connected in parallel with the second voltage divider resistor (R2). A Zener diode (DZ) is connected in parallel between the second output terminal and ground.

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