阅读说明：本技术 火焰离子检测装置、检测方法以及检测电路 (Flame ion detection device, detection method and detection circuit ) 是由 刘明雄 罗淦恩 姚家前 潘叶江 于 2021-07-29 设计创作，主要内容包括：本发明提供了一种火焰离子检测装置,包括炉头(1)和点火感应针(2)。点火感应针(2)包括感应负极(21)和感应正极(22),其中所述感应负极(21)接触火焰根部,所述感应正极(22)接触火焰外焰。其中,所述感应负极(21)与所述炉头(1)并联,并且在所述炉头(1)接触不良时使用。该火焰离子检测装置使负极与火焰的接触面积远大于正极,增大离子电流,并增加一个与炉头并联的负极,使在炉头接触不良时起用该负极,提高可靠性。(The invention provides a flame ion detection device which comprises a furnace end (1) and an ignition induction needle (2). The ignition induction needle (2) comprises an induction negative electrode (21) and an induction positive electrode (22), wherein the induction negative electrode (21) is in contact with the root of the flame, and the induction positive electrode (22) is in contact with the flame outer flame. The induction negative electrode (21) is connected with the burner (1) in parallel and is used when the burner (1) is in poor contact. This flame ion detection device makes the area of contact of negative pole and flame far away more than the positive pole, increase ion current to increase a negative pole parallelly connected with the furnace end, make when the furnace end contact is not good play this negative pole, improve the reliability.)

1. A flame ion detection device, comprising:

a furnace end (1); and

the ignition induction needle (2) comprises an induction negative electrode (21) and an induction positive electrode (22), wherein the induction negative electrode (21) is contacted with the root of the flame, and the induction positive electrode (22) is contacted with the flame outer flame;

the induction negative electrode (21) is connected with the burner (1) in parallel and is used when the burner (1) is in poor contact.

2. The flame ion detection device of claim 1, wherein one end of the induction negative electrode (21) is bent or spiral to increase an induced current.

3. The voice recognition system according to claim 2, wherein one end of the sensing anode (22) is bent, and the sensing anode (22) is a discharge end, and forms a proximity protrusion with the sensing cathode (21) at an end portion or a middle portion to facilitate discharge.

4. A method of flame ion detection, comprising:

setting a reference voltage of the comparator to a default value and generating a flame detection excitation signal;

judging whether the comparator is turned into a flame state, if so, confirming that flame is generated, and if not, increasing the reference voltage of the comparator by one level and continuing the step;

by analogy, under the condition that no overturn occurs, when the reference voltage of the comparator reaches a preset maximum value, no flame is determined.

5. The flame ion detection method of claim 4, wherein after ignition, a flame detection excitation signal is generated in a gap where discharge is stopped, and an ignition process and a flame detection excitation signal generation process are separated, thereby avoiding interference of ignition with ion current detection.

6. A flame ion detection circuit is characterized in that Q1, T1, D1, C1, T2 and U1 are electrically connected and form a two-stage boosting high-voltage generation circuit, T2 and D1 discharge electrodes form a high-voltage discharge circuit, C1 and T2 generate flame excitation signals, T2 outputs secondary voltage, R1 and C2 electrodes form an ion current circuit, an ion current difference value generates negative voltage on C2 to an input end of a comparator, wherein Q1 is a three-stage rectifier tube, D1 is a two-stage rectifier tube, T1 and T2 are transformers, C1 and C2 are capacitors, R1 is a resistor, and U1 is a silicon controlled switch.

7. The flame ion detection circuit of claim 6, wherein ignition is controlled by a CPU, wherein Q₁Turn on by CPU generated PWM control, the Q₁And T1 form a flyback boost switching power supply, generate voltage and store energy through C1, U1 turns on to generate instantaneous large current and discharge through high voltage transformer T2.

8. The flame ion detection circuit of claim 7, wherein the comparator is a comparator built in a CPU, an input voltage of the comparator is a bias voltage, wherein Q1 is turned off, the CPU controls T2 to be turned on, a flame detection excitation signal is generated at the secondary stage of T2 through discharge of C1, C2 is charged and discharged, when a flame is generated, a forward charging shunt current is generated, a negative voltage is generated on C2, a superposed voltage is generated between the voltage of C2 and the bias voltage through the bias current of R3\ R4, and the comparator is used for determining whether the flame is generated or not through whether the comparator is turned over or not.

9. The flame ion detection circuit of claim 8,

the input end of the comparator is provided with a multi-stage analog switch, and the reference voltage is divided through a resistance network to obtain multi-stage reference voltage;

the reference voltage is set to be the lowest, when the input voltage of the comparator is the bias voltage, the bias voltage is larger than the reference voltage, the reference voltage is the positive phase input, the output of the comparator is low and is not turned over, the comparator is judged to be flameless, when the excitation voltage is charged and discharged at C2, a larger negative voltage is generated, the input voltage of the comparator is C2, the sum of the negative voltage and the bias voltage is smaller than the reference voltage, and the comparator is turned over and is judged to be flameless;

and when the flame is judged to be not generated, increasing the reference voltage step by step to judge whether the flame is generated.

10. The flame ion detection circuit of claim 9,

the initial value of the reference voltage is 1.2v, 64-stage voltage division is carried out, the reference voltage of each stage is 1.2/64-20 mv, and the bias voltage is 150 mv;

and if the input voltage is greater than the reference voltage, the reference voltage is increased step by step for judgment.

Technical Field

The invention relates to the field of kitchen utensils, in particular to a flame ion detection device, a detection method and a detection circuit.

Background

The gas cooker adopts flame ion detection to carry out flameout protection, the contact area of the electrode and the flame is related to the sensitivity of flame detection, and related researches show that the larger the contact area of the anode and the flame is, the higher the sensitivity of flame detection is, and when the contact area reaches a certain value, the sensitivity of flame detection is not increased. Similarly, the larger the contact area between the cathode and the flame sensitivity is, the higher the flame detection sensitivity is, and when the contact area reaches a certain value, the flame detection sensitivity is not increased any more. And the area of the negative electrode is far larger than that of the positive electrode, so that the sensitivity is higher, namely, the negative electrode has more influence on the high sensitivity. Stove ionic flame detects, uses the furnace end as the negative pole mostly, and area of contact is very big, because the reason of technology, the furnace end adopts removable structure more to the material of furnace end is also diversified, leads to after using a period, produces the furnace end poor ground connection. The double-electrode flame sensing is generated, the existing double-electrode ion sensing is small in contact, a symmetrical structure is adopted, ion current is small, positive and negative ion current is the same, the existing ion flame sensing circuit cannot sense flame, flame sensitivity is remarkably improved through changes of electrode shapes and contact flame forms, and effective flame signals cannot be effectively detected by adopting the existing flame ion detection circuit.

Disclosure of Invention

The invention aims to provide a flame ion detection device, which enables the contact area of a negative electrode and flame to be far larger than that of a positive electrode, increases the ion current, and increases a negative electrode connected with a burner in parallel, so that the negative electrode is activated when the burner is in poor contact, and the reliability is improved.

The invention also aims to provide a flame ion detection method, which can work in a time-sharing manner with ignition and flame, avoid the interference of ignition on the detection of ion current, reduce the fluctuation of the ion current, and automatically eliminate the influence of system errors by adopting a dynamic comparison method.

The invention also aims to provide a flame ion detection circuit.

In order to realize the purpose of the invention, the invention adopts the following technical scheme:

according to one aspect of the invention, a flame ion detection device is provided, which comprises a furnace end and an ignition induction needle. The ignition induction needle comprises an induction negative electrode and an induction positive electrode, wherein the induction negative electrode is in contact with the root part of the flame, the induction positive electrode is in contact with the flame outer flame, and the induction negative electrode is connected with the burner in parallel and is used when the burner is in poor contact.

According to an embodiment of the present invention, one end of the sensing cathode is bent or screwed to increase the induced current.

According to an embodiment of the present invention, one end of the sensing positive electrode is bent, and the sensing positive electrode is a discharging end, and a proximity protrusion is formed at an end or a middle portion of the sensing positive electrode and the sensing negative electrode to facilitate discharging.

According to another aspect of the present invention, there is provided a flame ion detection method, including: setting a reference voltage of the comparator to a default value and generating a flame detection excitation signal; judging whether the comparator is turned into a flame state; if the overturn happens, the generation of flame is confirmed; if the comparator is not turned over, the reference voltage of the comparator is increased by one step, and the step is continued; by analogy, under the condition that no overturn occurs, when the reference voltage of the comparator reaches a preset maximum value, no flame is determined.

According to an embodiment of the present invention, after ignition, a flame detection excitation signal is generated in a gap where discharge is stopped, and an ignition process and a flame detection excitation signal generation process are separated, thereby avoiding interference of ignition on ion current detection.

According to another aspect of the invention, a flame ion detection circuit is provided, wherein Q1, T1, D1, C1, T2 and U1 are electrically connected and form a two-stage boosting high-voltage generation circuit, discharge electrodes T2 and D1 form a high-voltage discharge circuit, C1 and T2 generate flame excitation signals, a secondary output of T2, electrodes R1 and C2 form an ion current circuit, and an ion current difference value generates a negative voltage on C2 to an input end of a comparator, wherein Q1 is a three-stage rectifier tube, D1 is a two-stage rectifier tube, T1 and T2 are transformers, C1 and C2 are capacitors, R1 is a resistor, and U1 is a thyristor switch.

According to an embodiment of the invention, wherein ignition is controlled by the CPU, wherein Q₁Turn on by CPU generated PWM control, the Q₁And T1 form a flyback boost switch circuitThe source, generating voltage and storing energy through C1, U1 turns on generating an instantaneous large current and generating a discharge through high voltage transformer T2.

According to an embodiment of the present invention, the comparator is a comparator built in the CPU, an input voltage of the comparator is a bias voltage, wherein Q1 is turned off, the CPU controls T2 to be turned on, a flame detection excitation signal is generated at a secondary stage of T2 through discharge of C1, C2 is charged and discharged, when a flame is generated, a forward charging shunt current is generated, a negative voltage is generated at C2, a voltage obtained by superimposing the voltage of C2 with the bias voltage enters the comparator through the bias current of R3\ R4, and whether the flame is generated is determined through whether the comparator is turned over.

According to an embodiment of the present invention, a multi-stage analog switch is disposed at an input end of the comparator, and a reference voltage is divided by a resistor network to obtain a multi-stage reference voltage;

the reference voltage is set to be the lowest, when the input voltage of the comparator is the bias voltage, the bias voltage is larger than the reference voltage, the reference voltage is the positive phase input, the output of the comparator is low and is not turned over, the comparator is judged to be flameless, when the excitation voltage is charged and discharged at C2, a larger negative voltage is generated, the input voltage of the comparator is C2, the sum of the negative voltage and the bias voltage is smaller than the reference voltage, and the comparator is turned over and is judged to be flameless;

and when the flame is judged to be not generated, increasing the reference voltage step by step to judge whether the flame is generated.

According to an embodiment of the present invention, the initial value of the reference voltage is 1.2v, 64 steps of voltage division are performed, each step of reference voltage is 1.2/64-20 mv, and the bias voltage is 150 mv;

and if the input voltage is greater than the reference voltage, the reference voltage is increased step by step for judgment.

One embodiment of the present invention has the following advantages or benefits:

the flame ion detection device adopts a multi-electrode ion induction mode. The furnace end is a negative electrode, the ignition induction needle comprises an induction positive electrode and an induction negative electrode, the negative electrode is used when the furnace end is not in good contact, and reliability is improved. The induction negative pole and the induction positive pole are of an upper-lower structure, the negative pole is in contact with the root of the flame, the positive pole is in contact with the outer flame, the upper-lower structure is consistent with the direction of the ion flow of the flame, and the problem that the difference value detection cannot be adopted due to the fact that the positive current and the negative current are the same in size when the currents are generated in a bilateral symmetry mode is solved. The positive pole is induced to buckle at the tip, makes contact flame more reliable when increasing area of contact to increase ion current. The negative electrode contact flame area has larger influence on flame ion current, and a broken line mode is adopted, so that the maximum contact area of a minimum structure is increased, and the ion current is increased.

Drawings

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

FIG. 1 is a schematic diagram illustrating a flame ion detection apparatus according to an exemplary embodiment.

FIG. 2 is a schematic diagram illustrating a method of flame ion detection according to an exemplary embodiment.

FIG. 3 is a schematic diagram illustrating a flame ion detection circuit according to an exemplary embodiment.

Wherein the reference numerals are as follows:

1. a furnace end; 2. an ignition induction needle; 21. sensing a negative electrode; 22. and (6) inducing the positive electrode.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed description will be omitted.

The terms "a," "an," "the," "said" are used to indicate the presence of one or more elements/components/etc.; the terms "comprising" and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc.

As shown in fig. 1, fig. 1 is a schematic diagram illustrating a flame ion detection apparatus provided by the present invention.

The flame ion detection device provided by the embodiment of the invention comprises a furnace end 1 and an ignition induction needle 2. The ignition induction needle 2 comprises an induction negative electrode 21 and an induction positive electrode 22, wherein the induction negative electrode 21 is contacted with the root of the flame, and the induction positive electrode 22 is contacted with the flame outer flame; the induction negative electrode 21 is connected in parallel with the burner 1 and is used when the burner 1 is in poor contact.

According to the flame ionic current principle, two electrodes are in contact with flame, and direct current voltage is applied to two ends of each electrode to generate ionic current. The ignition sensing pin 2 includes a sensing cathode 21 and a sensing anode 22. Namely, an electrode connected with the furnace end 1 in parallel is added, and a symmetrical structure is adopted, so that the contact flame of the positive electrode and the negative electrode is symmetrical, and the generated ion current is also symmetrical. The flame induction needle 2 is used as a high-voltage discharge end at the same time, and the structure shape enables the end to form a nearest discharge end, so that the discharge distance is ensured. The flame ionization current is greatly increased by the structure of the flame induction needle 2. The ignition induction needle 2 is in an upper and lower structure when contacting with the flame, the induction negative electrode 21 is in contact with the root of the flame, and the induction positive electrode 22 is in contact with the outer flame. The upper and lower structure is consistent with the direction of flame ion flow, so that the problem that the same magnitude of forward and reverse current generated by bilateral symmetry contact cannot be detected by difference is solved.

In a preferred embodiment of the present invention, one end of the sensing cathode 21 is bent or spiraled to increase the induced current.

As shown in fig. 1, the influence of the area of the induction negative electrode 21 contacting the flame on the flame ion current is larger, so that it is necessary to increase the contact area as much as possible. It can be bent or spiral at least once to increase the induced current, so that the maximum contact area of the minimum structure increases the ionic current.

In a preferred embodiment of the present invention, one end of the sensing anode 22 is bent, and the sensing anode 22 is a discharge end, and forms a proximity protrusion with the sensing cathode 21 at the end or the middle to facilitate discharge.

As shown in fig. 1, the induction positive electrode 22 is bent at the end portion, so that the contact area is increased, the contact flame is more reliable, and the ion current is increased.

As shown in fig. 2, fig. 2 is a schematic diagram illustrating a flame ion detection method provided by the present invention.

The flame ion detection method provided by the embodiment of the invention comprises the following steps: setting a reference voltage of the comparator to a default value and generating a flame detection excitation signal; judging whether the comparator is turned into a flame state, if so, confirming that flame is generated, and if not, increasing the reference voltage of the comparator by one level and continuing the step; by analogy, under the condition that no overturn occurs, when the reference voltage of the comparator reaches a preset maximum value, no flame is determined.

The CPU is internally provided with a comparator, the positive end of the CPU is different from the traditional grounding method, a multi-stage analog switch is adopted, the reference voltage is divided through a resistance network, and the analog switch is switched to change the input voltage of the comparator. The flame detection sensitivity is improved by a dynamic threshold value changing method. The method comprises the following steps: 1. setting a comparator comparison voltage reference value as a default value, detecting whether the comparator is turned into a flame state or not in a flame excitation signal generation window, judging that flame is generated if the comparator is turned over, and continuing to the first step. 2. Two detection time windows are generated, one with and one without the flame excitation signal. 3. Increasing the comparison reference voltage of the comparator by one stage, judging whether the comparator is overturned under the condition of existence of an excitation signal, judging that flame exists if the comparator is overturned for multiple times, and returning to the first step; otherwise, the reference voltage is continuously increased. 4. And judging whether the comparator is overturned or not in the state of the excitation signal, if so, judging that flame exists, and otherwise, if the comparison reaches a preset maximum value, judging that no flame exists. 5. If the fire is judged to be not flaming for a plurality of times, the fire is judged to be not flaming and corresponding operation is executed.

In a preferred embodiment of the invention, after ignition, a flame detection excitation signal is generated in the gap where discharge is stopped, and the ignition process and the flame detection excitation signal generation process are separated, so that interference of ignition on ion current detection is avoided.

As shown in fig. 2, the ignition and the flame work in a time-sharing manner, so that the interference of the ignition on the detection of the ion current is avoided, the fluctuation of the ion current is reduced, the influence of system errors is automatically eliminated by adopting a dynamic comparison method, the ion current is a relative value (relative to the ion current without a signal), when the flame returns to a normal value (a larger value), the fluctuation is also larger, and the small threshold value can generate misjudgment on the contrary. The judgment is automatically started from the maximum threshold value, so that the method adapts to large ion current, and no misjudgment is generated corresponding to a large threshold value. Through a dynamic mode, a small current small threshold value and a large current large threshold value are compared with an ion current judging method; the traditional method is subverted, so that the judgment reliability of flame ionic current is greatly improved, and the method is suitable for the problems that a furnace end is not grounded and the ionic current of an induction needle is small.

The flame ion detection method of the invention works in time-sharing manner of ignition and flame, avoids the interference of ignition on the detection of ion current, reduces the fluctuation of the ion current, adopts a dynamic comparison method, automatically eliminates the influence of system error, the ion current is a relative value (relative to the ion current without signal), when the flame returns to a normal value (larger value), the fluctuation is also larger, and the small threshold value can generate misjudgment on the contrary. The judgment is automatically started from the maximum threshold value, so that the method adapts to large ion current, and no misjudgment is generated corresponding to a large threshold value. Through a dynamic mode, a small current small threshold value and a large current large threshold value are compared with an ion current judging method; the traditional method is subverted, so that the judgment reliability of flame ionic current is greatly improved, and the method is suitable for the problems that a furnace end is not grounded and the ionic current of an induction needle is small.

As shown in fig. 3, fig. 3 is a schematic diagram of a flame ion detection circuit provided by the present invention.

The flame ion detection circuit comprises Q1, T1, D1, C1, T2 and U1 which are electrically connected and form a two-stage boosting high-voltage generation circuit, discharge electrodes T2 and D1 form a high-voltage discharge circuit, flame excitation signals are generated by C1 and T2, secondary output of T2 is achieved, electrodes R1 and C2 form an ion current circuit, an ion current difference value generates negative voltage on C2 to an input end of a comparator, wherein Q1 is a three-stage rectifier tube, D1 is a two-stage rectifier tube, T1 and T2 are transformers, C1 and C2 are capacitors, R1 is a resistor, and U1 is a silicon controlled switch.

As shown in fig. 3, Q1 is electrically connected to T1. T1 is electrically connected to D1 and then to T2 and C1, respectively, with C1 grounded. U1 is electrically connected to T2 and ground. T2 is electrically connected to R1, C2 is electrically connected to R1 and ground.

In a preferred embodiment of the invention, ignition is controlled by a CPU, wherein Q1 is turned on by Pulse Width Modulation (PWM) control generated by the CPU, Q1 and T1 constitute a flyback boost switching power supply, generate voltage and store energy through C1, and U1 is turned on to generate instantaneous large current and discharge through a high voltage transformer T2.

After Q1 is opened, Q1 is communicated with T1, and T1 generates voltage and transmits the voltage to C1 for storage. The U1 is conducted to generate an instantaneous large current and discharge through the high-voltage transformer T2, and finally ignition is achieved.

In a preferred embodiment of the invention, the comparator is a comparator built in a CPU, the input voltage of the comparator is a bias voltage, wherein Q1 is turned off, the CPU controls T2 to be turned on, a flame detection excitation signal is generated at the secondary stage of T2 through the discharge of C1, C2 is charged and discharged, when a flame is generated, a forward charging shunt current is generated, a negative voltage is generated on C2, a voltage obtained by superimposing the voltage of C2 with the bias voltage enters the comparator through the bias current of R3\ R4, and whether the flame is generated is determined through whether the comparator is turned over.

Wherein Q1 turns off the ignition process and turns on the flame detection. The CPU controls the conduction of T2, and generates a flame detection excitation signal, which is a sine wave of 50v or more, in the secondary stage of T2 by the discharge of C1.

In a preferred embodiment of the present invention, a multi-stage analog switch is disposed at an input end of the comparator, and the reference voltage is divided by a resistor network to obtain a multi-stage reference voltage;

the reference voltage is set to be the lowest, when the input voltage of the comparator is the bias voltage, the bias voltage is larger than the reference voltage, the reference voltage is the positive phase input, the output of the comparator is low and is not turned over, the comparator is judged to be flameless, when the excitation voltage is charged and discharged at C2, a larger negative voltage is generated, the input voltage of the comparator is C2, the sum of the negative voltage and the bias voltage is smaller than the reference voltage, and the comparator is turned over and is judged to be flameless;

and when the flame is judged to be not generated, increasing the reference voltage step by step to judge whether the flame is generated.

The initial value of the reference voltage is 1.2v, 64-stage voltage division is carried out, the reference voltage of each stage is 1.2/64-20 mv, and the bias voltage is 150 mv;

and if the input voltage is greater than the reference voltage, the reference voltage is increased step by step for judgment.

As shown in fig. 3, the comparator is a comparator built in the CPU, the input end of the comparator is designed with a reference voltage through an analog switch, as shown in fig. 5, the internal power supply is referenced to 1.2V, and the voltage is divided by the analog switch group and the resistor network to obtain a 64-level reference voltage. The voltage of each stage is changed to 1.2/64 and is about 20mV per stage.

The default reference voltage is set to 0 th gear, i.e., 20 mV. When there is no flame, the input voltage of the comparator is an offset voltage, about 150mV is much greater than 20mV, and the comparator output is low because the internal reference voltage is the positive input.

When the fuel is normally combusted, the excitation voltage is charged and discharged at C2 to generate a large negative voltage which is less than 20mV, and the comparator is turned over. It is judged that flame is generated.

When in the initial stage of ignition or small fire, the ion current is small, the negative voltage on the capacitor is small, and under the superposition of the bias voltage, a voltage which is larger than 20mV and smaller than the bias voltage is generated. Changing the reference voltage of the comparator always flips a bit.

When the reference voltage of the comparator is greater than the external bias voltage, no matter whether the excitation signal exists or not, the comparator is low and does not turn over, and therefore the flame is judged to be not flame.

For example, when the input of the comparator is 80mV, the bias voltage is 150mV when no excitation signal exists, the output of the comparator is low, the excitation signal is added to be 80mV, and when the reference voltage is 20mV, the output of the comparator is low and is not inverted; the reference voltage is gradually increased, and when the reference voltage is 100mV, the comparator is turned over, so that the flame can be judged to exist.

The comparator internal reference voltage is not set to 120mV initially. Because the bias voltage is divided by the resistors and is influenced by precision, the bias voltage is changed to be near 120mV in some machines due to the error of the superposed power supply, and thus some machines are not overturned at 120mV, and misjudgment is generated.

Adjusting the reference voltage is an adaptive bias voltage and setting the reference voltage at the point nearest to the bias voltage to optimize sensitivity.

When the flame is stable, the ion current is increased, and the flame does not need to be judged in a high-sensitivity mode, so that the reliability of judgment when the flame is normally combusted is improved.

After all, the time is short in the ignition stage, the damage caused by misjudgment is small, and flameout protection can still be carried out later. Ion current is often higher than the ignition stage when the small fire to the gas volume of revealing is very little when the small fire, promotes the balance of sensitivity and reliability through the better assurance of dynamic flame ion current.

In embodiments of the present invention, the term "plurality" means two or more unless explicitly defined otherwise. The terms "mounted," "connected," "secured," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection. Specific meanings of the above terms in the embodiments of the present invention can be understood by those of ordinary skill in the art according to specific situations.

In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the referred devices or units must have a specific direction, be configured in a specific orientation, and operate, and thus, should not be construed as limiting the embodiments of the present invention.

In the description herein, the appearances of the phrase "one embodiment," "a preferred embodiment," or the like, are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made to the present embodiment by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.