CN211019259U - Limiting current oxygen sensor heating circuit for steaming oven - Google Patents
Limiting current oxygen sensor heating circuit for steaming oven Download PDFInfo
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- CN211019259U CN211019259U CN201922135838.2U CN201922135838U CN211019259U CN 211019259 U CN211019259 U CN 211019259U CN 201922135838 U CN201922135838 U CN 201922135838U CN 211019259 U CN211019259 U CN 211019259U
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Abstract
The utility model belongs to the technical field of the oxygen sensor, concretely relates to limit current oxygen sensor heating circuit for steam oven, control chip, heating drive circuit, oxygen sensor heater port including electric connection, be provided with input voltage control port and output voltage control port on the control chip, heating drive circuit includes voltage conversion chip, input control triode, output control triode and first resistance, the input electric connection input control triode and the voltage source port of voltage conversion chip, the output of voltage conversion chip electric connection first resistance and output control triode in proper order, first resistance parallel connection has the second resistance, second resistance electric connection has the voltage output end, output control triode parallel connection has the third resistance. The utility model discloses a heating drive circuit with adjustable design carries out timing and vary voltage control to the voltage of applying to the oxygen sensor heater, has avoided taking place thermal shock damage equipment.
Description
Technical Field
The utility model relates to an oxygen sensor technical field particularly, relates to limit current oxygen sensor heating circuit for steam oven.
Background
When food is steamed and baked by the steaming and baking oven, in order to keep the taste and the nutritive value of the food, the humidity of the steaming and baking needs to be accurately controlled. At present, it is known to install a limiting current oxygen sensor in an inner cavity of a steam oven, and to calculate the humidity of the inner cavity of the steam oven by detecting the oxygen concentration of the inner cavity of the steam oven and using a certain proportional relationship between the oxygen concentration and the humidity. In order to detect the oxygen concentration, the sensor must operate at a suitable temperature point, requiring control of the heating of the sensor. Patent CN106370711A proposes a method for detecting humidity, but does not specifically describe how to perform heating control on the oxygen sensor. Some patents describe the heating temperature control of a limiting current oxygen sensor, but are all based on the exhaust gas environment in an automobile: the temperature of the oxygen sensor is adjusted by measuring the internal resistance of the oxygen sensor and controlling the heating voltage by using the relationship between the internal resistance and the temperature of the oxygen sensor. Different from the environment of the inner cavity of the steaming oven, the flow velocity of waste gas is large, and the temperature of the sensor is greatly influenced by airflow, so the temperature of the sensor must be accurately measured, and the steaming oven is basically in a stable airflow environment. In addition, the working temperature of the limiting current oxygen sensor is about 650 ℃, when the steaming oven works, the air in the inner cavity contains a large amount of water vapor, when the temperature of the wall of the inner cavity is very low, the water vapor can form condensed water to be condensed on the wall of the inner cavity, if the sensor is directly heated to about 650 ℃, the condensed water contacts the high-temperature ceramic chip of the oxygen sensor, the risk of cracking of the sensing element is increased due to thermal shock, and the sensor is easy to fail.
SUMMERY OF THE UTILITY MODEL
In order to solve the problems that when a steaming and baking oven works, a circuit structure is complex by adopting a general limiting current oxygen sensor scheme, the cost is high, and condensed water is easy to contact a high-temperature ceramic chip of the oxygen sensor, so that the sensor is cracked and fails due to thermal shock, the limiting current oxygen sensor heating circuit for the steaming and baking oven is provided.
The limiting current oxygen sensor heating circuit for the steam oven comprises a control chip, a heating driving circuit and an oxygen sensor heater port which are electrically connected in sequence, wherein an input voltage control port and an output voltage control port are arranged on the control chip, the heating driving circuit comprises a voltage conversion chip, an input control triode, an output control triode and a first resistor, the input end of the voltage conversion chip is electrically connected with the input control triode and a voltage source port, the output end of the voltage conversion chip is electrically connected with the first resistor and the output control triode in sequence, the first resistor is connected with a second resistor in parallel, the second resistor is electrically connected with a voltage output end, the output control triode is connected with a third resistor in parallel, the input voltage control port is electrically connected with the base electrode of the input control triode, and the output voltage control port is electrically connected with the base electrode of the output control triode, the voltage output end is electrically connected with the port of the oxygen sensor heater.
Further, the first resistor is a variable resistor.
Further, the control chip is an 8051 single chip microcomputer.
Furthermore, the model of the voltage conversion chip is MP 1584.
Furthermore, the input control triode and the output control triode are both 8050 in model.
The heating method of the limiting current oxygen sensor heating circuit for the steam oven comprises the following steps:
a. the input voltage control port of the control chip outputs high level, the base electrode of the input control triode inputs high level, and the input control triode is conducted; the output voltage control port of the control chip outputs a low level, the base electrode of the output control triode inputs the low level, and the output control triode is not conducted; the voltage output port outputs 2-3V voltage to enable the oxygen sensor heater to start to slowly heat;
b. after heating for 30-180S, the input voltage control port outputs high level, the base electrode of the input control triode inputs high level, and the input control triode is conducted; the output voltage control port of the control chip outputs high level, the base electrode of the output control triode inputs high level, and the output control triode is also conducted; the voltage output port outputs 5-8V voltage to make the oxygen sensor heater work normally.
c. When the initial voltage and the normal working voltage of the oxygen sensor heater need to be changed, the resistance value of the first resistor is adjusted.
The utility model has the advantages that:
1. the timing step-by-step voltage supply of the heater can be realized, and the phenomenon that the element is damaged by thermal shock due to the fact that large voltage is directly applied is avoided.
2. The structure is simple, and the popularization and the use are convenient.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic block diagram of the connection of a limiting current oxygen sensor heating circuit for a steam oven;
FIG. 2 is a schematic circuit diagram of a heater driver circuit;
fig. 3 is a schematic circuit diagram of the control chip.
The attached drawings are as follows:
1-control chip, 11-input voltage control port, 12-output voltage control port, 2-heating drive circuit, 21-voltage conversion chip, 22-input control triode, 23-output control triode, 24-first resistor, 25-voltage source port, 26-second resistor, 27-voltage output end, 28-third resistor and 3-oxygen sensor heater port.
Detailed Description
In order to solve the problems that when a steaming and baking oven works, a circuit structure is complex by adopting a general limiting current oxygen sensor scheme, the cost is high, and condensed water is easy to contact a high-temperature ceramic chip of the oxygen sensor, so that the sensor is cracked and fails due to thermal shock, the limiting current oxygen sensor heating circuit for the steaming and baking oven is provided.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the drawings in the embodiments of the present invention are combined below to clearly and completely describe the technical solutions in the embodiments of the present invention, and obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
As shown in fig. 1 to 3, the limiting current oxygen sensor heating circuit for a steam oven provided in this embodiment includes a control chip 1, a heating driving circuit 2, and an oxygen sensor heater port 3, which are electrically connected in sequence, the control chip 1 is provided with an input voltage control port 11 and an output voltage control port 12, the heating driving circuit 2 includes a voltage conversion chip 21, an input control triode 22, an output control triode 23, and a first resistor 24, an input end of the voltage conversion chip 21 is electrically connected to the input control triode 22 and a voltage source port 25, an output end of the voltage conversion chip 21 is electrically connected to the first resistor 24 and the output control triode 23 in sequence, the first resistor 24 is connected in parallel to a second resistor 26, the second resistor 26 is electrically connected to a voltage output end 27, the output control triode 23 is connected in parallel to a third resistor 28, the input voltage control port 11 is electrically connected to the base of the input control triode 22, the output voltage control port 12 is electrically connected to the base of the output control triode 23, and the voltage output terminal 27 is electrically connected to the oxygen sensor heater port 3. Wherein the voltage source port 25 is used for accessing an external voltage source to obtain power for the operation of the heater.
The first resistor 24 is a variable resistor. The first resistor 24 designed by adopting the variable resistor can adjust the resistance value as required, thereby achieving the effect of adjusting the initial voltage and the normal working voltage output to the oxygen sensor heater.
The control chip is an 8051 singlechip. The 8051 single chip microcomputer is mature in technology, is provided with a storage for storing a control command and a timer for recording time, and is suitable for being used as a controller of the heating driving circuit 2 (the 8051 single chip microcomputer is already applied and popularized in technology, and the structure of the 8051 single chip microcomputer is not described herein again).
The model number of the voltage conversion chip is MP 1584. For a conventional buck chip, the high voltage provided by the voltage source connected to the voltage source port 25 can be converted to a low voltage suitable for use by the oxygen sensor heater.
The input control triode and the output control triode are both 8050 in model. The 8050 type triode is a very common NPN type crystal triode, has the advantage of stable performance, and can ensure the running stability of equipment.
The heating method of the limiting current oxygen sensor heating circuit for the steam oven comprises the following steps:
a. the input voltage control port of the control chip outputs high level, the base electrode of the input control triode inputs high level, and the input control triode is conducted; the output voltage control port of the control chip outputs a low level, the base electrode of the output control triode inputs the low level, and the output control triode is not conducted; the voltage output port outputs 2-3V voltage to enable the oxygen sensor heater to start to slowly heat;
b. after heating for 30-180S, the input voltage control port outputs high level, the base electrode of the input control triode inputs high level, and the input control triode is conducted; the output voltage control port of the control chip outputs high level, the base electrode of the output control triode inputs high level, and the output control triode is also conducted; the voltage output port outputs 5-8V voltage to make the oxygen sensor heater work normally.
c. When the initial voltage and the normal working voltage of the oxygen sensor heater need to be changed, the resistance value of the first resistor is adjusted.
Whereas V is known from the data sheet of MP1584 (link: https:// wenku. baidu. com/view/b2ef62e7 cbaiedd3383c 4bb4cf7ec4afe04a1b1be. html, see pages 3 and 10 for details)FBTypical values are 0.8V, VFB＝VDD*(R40+RP4)/(R40+RP4+R29),VDD＝VFB(R40+ RP4+ R29)/(R40+ RP4), where VDD is the voltage output by the voltage output terminal 27, RP4 is the first resistor 24, R29 is the second resistor 26, and R40 is the third resistor 28, when the resistance of RP4 and R40 is changed, the output VDD voltage can be changed. The present embodiment thus provides the first resistor 24 as a variable resistor for adjusting the output voltage as desired.
As is clear from fig. 2, R29 is preferably 100K, R40 is preferably 39K, and RP4 is adjusted to 14K. From the above data, it can be found that in step a. in this embodiment, VDD is 0.8 (100K +14K +39K)/(14K +39K) is 2.886V, and in step b. VDD is 0.8 (100K +14K)/14K is 6.510V.
The foregoing is a more detailed description of the present invention, and it is not intended that the present invention be limited to the specific details, since modifications and variations will be apparent to those skilled in the art.
Claims (5)
1. The limiting current oxygen sensor heating circuit for the steam oven is characterized by comprising a control chip, a heating driving circuit and an oxygen sensor heater port which are electrically connected in sequence, wherein an input voltage control port and an output voltage control port are arranged on the control chip, the heating driving circuit comprises a voltage conversion chip, an input control triode, an output control triode and a first resistor, the input end of the voltage conversion chip is electrically connected with the input control triode and a voltage source port, the output end of the voltage conversion chip is electrically connected with the first resistor and the output control triode in sequence, the first resistor is connected with a second resistor in parallel, the second resistor is electrically connected with a voltage output end, the output control triode is connected with a third resistor in parallel, the input voltage control port is electrically connected with the base electrode of the input control triode, the output voltage control port is electrically connected with the base of the output control triode, and the voltage output end is electrically connected with the port of the oxygen sensor heater.
2. The limiting current oxygen sensor heating circuit for a steam oven of claim 1, wherein the first resistor is a variable resistor.
3. The limiting current oxygen sensor heating circuit for the steaming oven of claim 1, wherein the control chip is an 8051 single chip microcomputer.
4. The limiting current oxygen sensor heating circuit for the steaming oven according to claim 1, wherein the voltage conversion chip is MP1584 in type.
5. The limiting current oxygen sensor heating circuit for a steam oven of claim 1, wherein the input control transistor and the output control transistor are both 8050 in type.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201922135838.2U CN211019259U (en) | 2019-12-03 | 2019-12-03 | Limiting current oxygen sensor heating circuit for steaming oven |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201922135838.2U CN211019259U (en) | 2019-12-03 | 2019-12-03 | Limiting current oxygen sensor heating circuit for steaming oven |
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| CN211019259U true CN211019259U (en) | 2020-07-14 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110839304A (en) * | 2019-12-03 | 2020-02-25 | 广州美闰陶热动电器有限公司 | Limiting current oxygen sensor heating circuit for steaming oven and heating method thereof |
| CN112180037A (en) * | 2020-09-15 | 2021-01-05 | 华帝股份有限公司 | Oxygen sensor and household appliance |
-
2019
- 2019-12-03 CN CN201922135838.2U patent/CN211019259U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110839304A (en) * | 2019-12-03 | 2020-02-25 | 广州美闰陶热动电器有限公司 | Limiting current oxygen sensor heating circuit for steaming oven and heating method thereof |
| CN112180037A (en) * | 2020-09-15 | 2021-01-05 | 华帝股份有限公司 | Oxygen sensor and household appliance |
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