CN214067011U

CN214067011U - Control device of oxygen concentration sensor

Info

Publication number: CN214067011U
Application number: CN202022491522.XU
Authority: CN
Inventors: 罗淦恩; 刘明雄; 高宁
Original assignee: Vatti Co Ltd
Current assignee: Vatti Co Ltd
Priority date: 2020-11-02
Filing date: 2020-11-02
Publication date: 2021-08-27
Anticipated expiration: 2030-11-02

Abstract

The utility model discloses an oxygen concentration sensor's controlling means. The device comprises an oxygen concentration sensor, a controller, a power supply, an electronic switch, a filtering module and a signal acquisition module; the electronic switch is connected between the input end of the filtering module and the positive electrode of the power supply, and the control end of the electronic switch is connected with the PWM signal output end of the controller; the output end of the filtering module is connected with the H + of the oxygen concentration sensor; the input end of the signal acquisition module is respectively connected with the H +, H-and S-ends of the oxygen concentration sensor, and the output end of the signal acquisition module is connected with the controller. By adjusting the duty ratio of the PWM signal, the heating resistance of the oxygen concentration sensor is equal to the heating resistance when the oxygen concentration sensor works at the optimal working temperature, so that the oxygen concentration sensor always works at the optimal working temperature, and the measurement accuracy of the oxygen concentration sensor can be improved.

Description

Control device of oxygen concentration sensor

Technical Field

The utility model belongs to the technical field of the sensor, concretely relates to oxygen concentration sensor's controlling means.

Background

An oxygen concentration sensor is a device for detecting the oxygen content in air. The method can be used for directly measuring the oxygen content in the environment, and can also be used for measuring the environment humidity based on the principle that the oxygen content in the air can indirectly reflect the water vapor content. For example, an oxygen concentration sensor using a zirconia ceramic chip as a core component can be used to measure the humidity of the detection inner cavity of the steaming and baking integrated machine, the working temperature of the steaming and baking integrated machine is 400-600 ℃, an electric control module which is designed in a matching way is used to heat and control the heating film covered on the surface of the chip, and meanwhile, the oxygen concentration value is calculated by measuring the magnitude of the pump current of the heating film, as shown in fig. 1. The optimal working temperatures of different zirconia ceramic chips are different, even the zirconia ceramic chips of the same type have differences, so that when the electronic control module performs heating control on the zirconia ceramic chips, the target temperature values reached can be different, and the zirconia ceramic chips cannot work at the optimal temperature, so that the detection precision is influenced. Therefore, the zirconia ceramic chip and the electronic control module need to be adapted by a set of calibration method to eliminate the influence.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems existing in the prior art, the utility model provides an oxygen concentration sensor's controlling means.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a control device of an oxygen concentration sensor comprises the oxygen concentration sensor, a controller, a power supply, an electronic switch, a filtering module and a signal acquisition module; the electronic switch is connected between the input end of the filtering module and the positive electrode of the power supply, and the control end of the electronic switch is connected with the PWM signal output end of the controller; the output end of the filtering module is connected with the H + of the oxygen concentration sensor; the input end of the signal acquisition module is respectively connected with the H +, H-and S-ends of the oxygen concentration sensor, and the output end of the signal acquisition module is connected with the controller.

Compared with the prior art, the utility model discloses following beneficial effect has:

the utility model discloses a set up oxygen concentration sensor, a controller, a power supply, electronic switch, filtering module and signal acquisition module, electronic switch connects between filtering module 'S input and power positive pole, the PWM signal output part of its control end and controller links to each other, filtering module' S output links to each other with oxygen concentration sensor 'S H +, H-, S-end links to each other with oxygen concentration sensor' S H + respectively, the output links to each other with the controller, duty cycle through adjustment PWM signal, make oxygen concentration sensor 'S heating resistor equal to the heating resistor of work when best operating temperature, make oxygen concentration sensor work at best operating temperature always, can improve oxygen concentration sensor' S measurement accuracy.

Drawings

FIG. 1 is a schematic diagram of an oxygen concentration sensor with a zirconia ceramic chip as a core member;

fig. 2 is a block diagram illustrating a control apparatus of an oxygen concentration sensor according to an embodiment of the present invention;

fig. 3 is a schematic circuit diagram of the connection of the oxygen concentration sensor with the filter module and the electronic switch, and U1 is the oxygen concentration sensor.

In fig. 2, 1 is an oxygen concentration sensor, 2 is a controller, 3 is a filtering module, 4 is an electronic switch, 5 is a power supply, and 6 is a signal acquisition module.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The control device of the oxygen concentration sensor 1 in the embodiment of the present invention, as shown in fig. 2, includes an oxygen concentration sensor 1, a controller 2, a power supply 5, an electronic switch 4, a filtering module 3 and a signal collecting module 6; the electronic switch 4 is connected between the input end of the filtering module 3 and the anode of the power supply 5, and the control end of the electronic switch is connected with the PWM signal output end of the controller 2; the output end of the filtering module 3 is connected with the H + of the oxygen concentration sensor 1; the input end of the signal acquisition module 6 is respectively connected with the H +, H-and S-ends of the oxygen concentration sensor 1, and the output end is connected with the controller 2.

In this embodiment, the device mainly comprises an oxygen concentration sensor 1, a controller 2, a power supply 5, an electronic switch 4, a filtering module 3 and a signal acquisition module 6, and the connection relationship among the modules is shown in fig. 2. Each module is described separately below.

The oxygen concentration sensor 1, which is a controlled object in the present embodiment, has a zirconia ceramic chip as a core member, and an operational schematic diagram thereof is shown in fig. 1. The total 4 pins are respectively H +, H-, S + and S-. When the device works normally, 7 +/-0.5V direct-current heating voltage is applied between H + and H-, and 0.8 +/-0.1V direct-current pump voltage is applied between S + and S-. Pump current I_PIs proportional to the oxygen concentration by measurement I_PThe oxygen concentration is calculated.

The controller 2 is mainly used for realizing certain data processing and control functions. For example, the heating voltage, the heating current, the pump current and the oxygen concentration are calculated by performing a/D conversion and necessary data processing on the signal input by the signal acquisition module 6; for another example, a PWM signal with an adjustable duty ratio is output to the electronic switch 4, and the duty ratio is changed to make the ratio R of the heating voltage to the heating current of the oxygen concentration sensor 1 (the input resistance from H + to H-end, also called as the heating resistance), so as to always maintain the ratio R of the heating voltage to the heating current when the oxygen concentration sensor 1 operates at the optimal operating temperature₀And is not changed. R₀The values of (a) are measured in advance by calibration, and a specific calibration method will be given later. Since the heating resistance R generally does not change in magnitude even when the temperature is constant and generally increases even when the temperature is increased, it is considered that the heating resistance R has a fixed relationship with the temperature. Heating resistor R always keeping optimum working temperature₀The oxygen concentration sensor 1 can be constantly operated at the optimum operating temperature, so that the measurement accuracy of the oxygen concentration can be improved.

The power supply 5, the electronic switch 4 and the filtering module 3 provide heating voltage for the oxygen concentration sensor 1 under the control of the PWM signal output by the controller 2. The power supply 5 typically employs a +12V battery voltage. The PWM signal is applied to the control terminal of the electronic switch 4 to control the on/off of the electronic switch 4 (on during the PWM high level period and off during the PWM low level period), so that the electronic switch 4 outputs a PWM pulse voltage with an amplitude of 12V, and the filter module 3 is charged and discharged to output a heating voltage proportional to the duty ratio.

And the signal acquisition module 6 is mainly used for sampling and amplifying the heating voltage, the heating current and the pump current. It includes three acquisition channels: the input end of one channel is connected with the H + end of the oxygen concentration sensor 1 and is used for realizing the heating voltage V_H+Sampling of (1); the input ends of the other two channels are respectively connected with H-and S-for sampling heating current and pump current. Since the current sampling is implemented by measuring the voltage on the sampling resistor, the value of the sampling resistor is generally small, and the voltage on the sampling resistor is also small, the current sampling signal (voltage) also needs to be amplified and then input to the controller 2.

As an alternative embodiment, the filtering module 3 is mainly composed of two capacitors C1, C2 connected in parallel between the H + terminal and ground.

This embodiment provides a technical solution of the filtering module 3. As shown in fig. 3, the filter module 3 is composed of two capacitors C1 and C2 connected in parallel. C2 is an electrolytic capacitor with a large capacitance value, and is used for realizing low-frequency filtering and converting an input PWM pulse signal into a direct current signal; the capacitance value of C1 is small for filtering out high frequency noise interference.

As an alternative embodiment, the electronic switch 4 mainly comprises a P-type MOS transistor Q1 and an N-type MOS transistor Q2; the source electrode of the Q1 is connected with the positive electrode of the power supply 5, the drain electrode is connected with the H + end, the grid electrode is connected with the drain electrode of the Q2 and one end of a resistor R1, and the other end of the R1 is connected with the positive electrode of the power supply 5; the source of the Q2 is grounded, the gate is connected with one end of the resistors R2 and R3, the other end of the resistor R3 is grounded, and the other end of the resistor R2 is connected with the PWM signal output end of the controller 2.

This embodiment provides a technical solution of the electronic switch 4. The electronic switch 4 of the present embodiment is constructed by separate elements, and mainly comprises a P-type MOS transistor Q1 and an N-type MOS transistor Q2. The specific connection relationship is shown in fig. 3. When the PWM is in a high level, Q2 and Q1 are conducted, the +12V power supply charges capacitors (C1 and C2), and the larger the duty ratio is, the higher the charging voltage is; when the PWM is at low level, Q2 and Q1 are cut off, and the capacitor discharges through a heating resistor (input resistor from H + to H-end).

The above description is only for the description of several embodiments of the present invention, but the scope of the present invention should not be considered as the protection scope of the present invention, in which all the equivalent changes or modifications or the equal-scale enlargement or reduction etc. made according to the design spirit of the present invention should be considered as falling into the protection scope of the present invention.

Claims

1. The control device of the oxygen concentration sensor is characterized by comprising the oxygen concentration sensor, a controller, a power supply, an electronic switch, a filtering module and a signal acquisition module; the electronic switch is connected between the input end of the filtering module and the positive electrode of the power supply, and the control end of the electronic switch is connected with the PWM signal output end of the controller; the output end of the filtering module is connected with the H + of the oxygen concentration sensor; the input end of the signal acquisition module is respectively connected with the H +, H-and S-ends of the oxygen concentration sensor, and the output end of the signal acquisition module is connected with the controller.

2. The control device of an oxygen concentration sensor according to claim 1, wherein the filtering module is mainly composed of two capacitors C1, C2 connected in parallel between the H + terminal and ground.

3. The control device of the oxygen concentration sensor according to claim 2, wherein the electronic switch is mainly composed of a P-type MOS transistor Q1 and an N-type MOS transistor Q2; the source electrode of the Q1 is connected with the positive electrode of the power supply, the drain electrode is connected with the H + end, the grid electrode is connected with the drain electrode of the Q2 and one end of a resistor R1, and the other end of the R1 is connected with the positive electrode of the power supply; the source of the Q2 is grounded, the grid of the Q2 is connected with one end of the resistors R2 and R3, the other end of the R3 is grounded, and the other end of the R2 is connected with the PWM signal output end of the controller.

4. The control device of the oxygen concentration sensor according to claim 3, wherein the signal acquisition module includes: the resistor series voltage division circuit is connected between the H + end and the ground; a resistor R4 connected between the H-terminal and the ground, a first operational amplifier connected with the H-terminal; a resistor R5 connected between the S-terminal and the ground, a second operational amplifier connected with the S-terminal; the output ends of the resistor series voltage division circuit, the first operational amplifier and the second operational amplifier are respectively connected with the controller.