阅读说明：本技术 一种车载尿素品质传感器浓度的修正方法 (Correction method for concentration of vehicle-mounted urea quality sensor ) 是由 邵培申 柯徐焕 王泓钦 于 2020-06-11 设计创作，主要内容包括：本发明提供一种车载尿素品质传感器浓度的修正方法,包括以下工艺步骤：步骤S1：测试装置的材料准备；步骤S2：测试装置的容器准备；步骤S3：测试过程；步骤S4：测试数据统计及拟合；步骤S5：浓度测量时,补偿延迟时间；步骤S6：获得当前测量时间；步骤S7：获得实际浓度。本发明校正密度不同的气泡环境下超声波飞行的时间,无需额外增加零件,节约成本,且响应速度快,还可以根据不同的精度要求,可以灵活地在相应的温度区间做详细的标定。(The invention provides a method for correcting the concentration of a vehicle-mounted urea quality sensor, which comprises the following process steps: step S1: material preparation of the test device; step S2: container preparation of the test device; step S3: a testing process; step S4: counting and fitting test data; step S5: compensating delay time when measuring the concentration; step S6: obtaining the current measuring time; step S7: the actual concentration is obtained. The invention corrects the flight time of the ultrasonic waves in the bubble environment with different densities, does not need to additionally add parts, saves the cost, has high response speed, and can flexibly carry out detailed calibration in corresponding temperature intervals according to different precision requirements.)

1. The method for correcting the concentration of the vehicle-mounted urea quality sensor is characterized by comprising the following process steps of:

step S1: material preparation of the test device: preparing two identical testing devices, wherein each device comprises a container for bearing liquid, a signal generator and an oscilloscope, and a bubble generating device is arranged in the container of one testing device;

step S2: container preparation of the test device: under the same test environment, the two test devices are filled with the same liquid, bubbles with different densities are introduced into the container provided with the bubble generating device, and the other container is not processed;

step S3: the testing process comprises the following steps: the generators of the two testing devices send out signals simultaneously, and the amplitude V and the flight time t of the ultrasonic signals received in the two containers are recorded;

step S4: test data statistics and fitting: fitting according to the peak value difference delta V, the flying time interval delta T and the solution temperature T containing bubbles of the ultrasonic signals received by the two testing devices to obtain a functional relation delta T of the temperature T, the time interval delta T and the peak value difference delta V, wherein the functional relation delta T is f (delta V, T);

step S5: compensation delay time during concentration measurement: measuring the actual solution temperature T and the ultrasonic attenuation amplitude DeltaV, and calculating the delay time Deltat through a function Deltat ═ f (DeltaV, T);

step S6: obtaining the current measuring time t plus delta t;

step S7: the actual concentration was obtained as g [ (T +. DELTA.t), T ].

2. The method for correcting the concentration of the on-vehicle urea quality sensor according to claim 1, characterized in that: in the step S1, the two containers are of the same type, and the signal generator and the oscilloscope are of the same type.

3. The method for correcting the concentration of the on-vehicle urea quality sensor according to claim 2, characterized in that: in the step S4, the difference between the peaks is the difference V1-V2 between the peaks of the first ultrasonic signal received by the two devices, and the time interval is the time interval t2-t1 of the first model of the two devices.

4. The method for correcting the concentration of the on-vehicle urea quality sensor according to claim 3, characterized in that: in step S3, the generator simultaneously sends out sinusoidal signals with constant amplitude.

Technical Field

The invention mainly relates to the field of automobile electronic industry, in particular to a method for correcting concentration of a vehicle-mounted urea quality sensor.

Background

In recent two-thirty years, with the rapid increase of automobile keeping quantity in the world, the brought automobile emission pollution is becoming serious. With the upgrading of national emission regulations, the demand for NOx emission of diesel engines is higher and higher. The urea quality sensor provides the current urea concentration for the aftertreatment SCR system, the SCR system calculates the urea amount required to be sprayed according to the current urea concentration, and the appropriate amount of urea can maximally treat NOx in tail gas and plays a key role in reducing NOx emission.

There are many different technical types of urea quality sensors, of which the ultrasonic type is most widely used. The working principle of the method is that ultrasonic waves reflected back are generated and received, the propagation speed of the ultrasonic waves is calculated, and the current urea concentration is calculated according to the difference of the propagation speeds of the ultrasonic waves in different urea solutions.

Under the influence of temperature and whole car operating mode, in practical application, often can produce more bubble in the urea case, cause ultrasonic energy loss, lead to the ultrasonic wave velocity of waves to calculate and present the deviation, and then cause the influence to urea concentration calculation.

At present, the intensity of a return signal is improved only by changing the working interval of a piezoelectric ceramic piece in domestic ultrasonic probe plants, and if dense bubbles are encountered in a working state, ultrasonic waves are hardly prevented from being influenced. The ultrasonic wave causes energy loss while passing through (or bypassing) different medium bands, and the propagation speed is changed, and the propagation speed directly influences the calculation of the concentration. Failure to accurately measure the urea solution concentration can result in inaccurate urea injection for aftertreatment and thus non-maximum NOx reduction in the exhaust. In severe cases, even the misinformation of the urea concentration can be caused, and the problems of torque limitation of the engine and the like can be caused.

Published chinese utility model patent, application No. CN201520580654.6, patent name: an on-board urea control system, application date: 2015-08-05, the invention relates to an on-board urea control system comprising: the switch unit is arranged at the output end of the vehicle-mounted urea; a controller electrically connected to a sensor provided in an exhaust pipe of a vehicle, the controller controlling the opening or closing of the switch unit according to a change in oxygen concentration value in the exhaust pipe measured by the sensor; when the oxygen concentration value is reduced, the controller controls the switch unit to be closed; when the oxygen concentration increases, the controller controls the switch unit to be turned on. The utility model provides an on-vehicle urea control system, this system are under the lower condition of on-vehicle urea content, and the output quantity of reasonable control urea prolongs the live time of on-vehicle urea.

Disclosure of Invention

Aiming at the defects in the prior art, the method provided by the invention aims at the problem of inaccurate urea concentration measurement in a bubble environment, and corrects the original concentration by the characteristic of energy loss of ultrasonic waves in different media, so that the measurement precision is improved.

The invention provides a method for correcting the concentration of a vehicle-mounted urea quality sensor, which comprises the following process steps:

step S1: material preparation of the test device: preparing two identical testing devices, wherein each device comprises a container for bearing liquid, a signal generator and an oscilloscope, and a bubble generating device is arranged in the container of one testing device;

step S2: container preparation of the test device: under the same test environment, the two test devices are filled with the same liquid, bubbles with different densities are introduced into the container provided with the bubble generating device, and the other container is not processed;

step S3: the testing process comprises the following steps: the generators of the two testing devices send out signals simultaneously, and the amplitude V and the flight time t of the ultrasonic signals received in the two containers are recorded;

step S4: test data statistics and fitting: fitting according to the peak value difference delta V, the flying time interval delta T and the solution temperature T containing bubbles of the ultrasonic signals received by the two testing devices to obtain a functional relation delta T of the temperature T, the time interval delta T and the peak value difference delta V, wherein the functional relation delta T is f (delta V, T);

step S5: compensation delay time during concentration measurement: measuring the actual solution temperature T and the ultrasonic attenuation amplitude DeltaV, and calculating the delay time Deltat through a function Deltat ═ f (DeltaV, T);

step S6: obtaining the current measuring time t plus delta t;

step S7: the actual concentration was obtained as g [ (T +. DELTA.t), T ].

In use, in the presence of bubbles in the urea solution, the ultrasonic flight time is corrected according to the amplitude variation of the measured ultrasonic echo, so as to correct the measured urea concentration

Preferably, in step S1, the two containers are of the same type, and the signal generator and the oscilloscope are of the same type.

Preferably, the difference between the peaks in step S4 is the difference V1-V2 between the peaks of the first ultrasonic signal received by the two devices, and the time interval is the time interval t2-t1 of the first model of the two devices.

Preferably, the generator simultaneously emits a sine signal of constant amplitude in step S3.

The invention has the beneficial effects that: the time of the ultrasonic wave flight in the bubble environment with different densities is corrected, additional parts are not needed, the cost is saved, the response speed is high, and detailed calibration can be flexibly carried out in corresponding temperature intervals according to different precision requirements.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a block diagram of the present invention;

in the figure, the position of the upper end of the main shaft,

1. a sinusoidal signal; 2. a signal generator; 3. an oscilloscope; 4. and a bubble generating device.

Detailed Description

In order to make the technical solutions of the present invention better understood and make the above features, objects, and advantages of the present invention more comprehensible, the present invention is further described with reference to the following examples. The examples are intended to illustrate the invention only and are not intended to limit the scope of the invention.

As shown in FIGS. 1-2, the present invention comprises the following steps:

step S1: material preparation of the test device: preparing two identical testing devices, wherein each device comprises a container for bearing liquid, a signal generator and an oscilloscope, and a bubble generating device is arranged in the container of one testing device;

step S2: container preparation of the test device: under the same test environment, the two test devices are filled with the same liquid, bubbles with different densities are introduced into the container provided with the bubble generating device, and the other container is not processed;

step S3: the testing process comprises the following steps: the generators of the two testing devices send out signals simultaneously, and the amplitude V and the flight time t of the ultrasonic signals received in the two containers are recorded;

step S4: test data statistics and fitting: fitting according to the peak value difference delta V, the flying time interval delta T and the solution temperature T containing bubbles of the ultrasonic signals received by the two testing devices to obtain a functional relation delta T of the temperature T, the time interval delta T and the peak value difference delta V, wherein the functional relation delta T is f (delta V, T);

step S5: compensation delay time during concentration measurement: measuring the actual solution temperature T and the ultrasonic attenuation amplitude DeltaV, and calculating the delay time Deltat through a function Deltat ═ f (DeltaV, T);

step S6: obtaining the current measuring time t plus delta t;

step S7: the actual concentration was obtained as g [ (T +. DELTA.t), T ].

In this embodiment, it is preferable that the two containers in step S1 are of the same type, and the signal generator and the oscilloscope are of the same type.

In this embodiment, the difference between the peaks in step S4 is the difference between the peaks of the first ultrasonic signal received by the two devices, V1-V2, and the time interval is the time interval t2-t1, t, of the first model of the two devices.

In this embodiment, it is preferable that the generator simultaneously emits a sinusoidal signal with a constant amplitude in step S3.

The above-described embodiments are merely illustrative of the principles and utilities of the present patent application and are not intended to limit the present patent application. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of this patent application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of this patent application.