CN110361198B - Vehicle evaporative emission system desorption flow fault detection device and method and vehicle - Google Patents
Vehicle evaporative emission system desorption flow fault detection device and method and vehicle Download PDFInfo
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- CN110361198B CN110361198B CN201910554135.5A CN201910554135A CN110361198B CN 110361198 B CN110361198 B CN 110361198B CN 201910554135 A CN201910554135 A CN 201910554135A CN 110361198 B CN110361198 B CN 110361198B
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Abstract
The invention discloses a device and a method for detecting desorption flow faults of a vehicle evaporative emission system and a vehicle, wherein the device comprises: the device comprises an ECU, a pressure sensor, a throttling hole, a switching valve, a first vacuum pipeline, a second vacuum pipeline and a third vacuum pipeline, wherein the diameter of the throttling hole is smaller than the inner diameter of the second vacuum pipeline, one end of the first vacuum pipeline is communicated with the atmosphere, the other end of the first vacuum pipeline is connected with the first end of the switching valve, the throttling hole is arranged on the first vacuum pipeline, one end of the second vacuum pipeline is communicated with the atmosphere, the other end of the second vacuum pipeline is connected with the second end of the switching valve, one end of the third vacuum pipeline is connected with the third end of the switching valve, the other end of the third vacuum pipeline is communicated with an atmosphere communication port of an activated carbon tank of a vehicle or is connected with an air inlet of a desorption control valve of the vehicle, and the pressure sensor is arranged on the third vacuum pipeline.
Description
Technical Field
The embodiment of the invention relates to the technical field of vehicle emission, in particular to a device and a method for detecting desorption flow faults of a vehicle evaporative emission system and a vehicle.
Background
Internal combustion engine powered vehicles are still the mainstream of the automotive market today. Internal combustion engine powered vehicles are typically fueled by an oil tank system. According to the current requirements of the emission regulations of light vehicles in China, an oil tank system needs to comprise an evaporative emission system to recover fuel steam in the oil tank system, so that the fuel steam is prevented from being discharged into the atmosphere to pollute the environment. A typical evaporative emission system includes an activated carbon canister for absorbing fuel vapor generated in a fuel tank, and a desorption control valve disposed in a pipe connecting the activated carbon canister and an intake pipe for controlling a desorption process of the fuel vapor absorbed in the activated carbon canister. The proportion of supercharged engine models in the current automobile market is increasing. Supercharged engine systems increase intake pressure through an electric or mechanical turbine to increase engine power. In order to meet the requirements of refueling tests and evaporative emission tests in the six-stage emission regulations of China, manufacturers need to increase the volume of an activated carbon tank and increase the desorption capacity of the activated carbon tank. For supercharged engine systems, many manufacturers can increase desorption flow by adding a high-load desorption pipeline, and for such systems, the six national emission regulations impose requirements on monitoring the added desorption pipeline so as to control evaporative emission pollution caused by high-load desorption pipeline faults.
Currently, a typical desorption flow fault detection method is to compare the pressure signal changes of a pressure sensor in an oil tank before and after a desorption control valve is opened to determine a desorption flow fault when an engine is running.
However, due to the pressure dynamics of the overall evaporative emission system, the tank pressure signal may oscillate periodically after the desorption control valve is opened. The oscillation characteristic of the oil tank pressure is determined by the design parameters of the fuel evaporation system, and the accuracy of judging the desorption flow fault based on the change of the oil tank pressure signal can be influenced. Therefore, the existing desorption flow fault detection method of the evaporative emission system is low in accuracy.
Disclosure of Invention
The invention provides a device and a method for detecting a desorption flow fault of an evaporative emission system of a vehicle and the vehicle, and aims to solve the technical problem that the existing method for detecting the desorption flow fault of the evaporative emission system is low in accuracy.
In a first aspect, an embodiment of the present invention provides a desorption flow fault detection apparatus for a vehicle evaporative emission system, including: the device comprises an ECU, a pressure sensor, an orifice, a switching valve, a first vacuum pipeline, a second vacuum pipeline and a third vacuum pipeline, wherein the diameter of the orifice is smaller than the inner diameter of the second vacuum pipeline;
one end of the first vacuum pipeline is communicated with the atmosphere, the other end of the first vacuum pipeline is connected with the first end of the switching valve, and the throttling hole is arranged on the first vacuum pipeline; one end of the second vacuum pipeline is communicated with the atmosphere, and the other end of the second vacuum pipeline is connected with the second end of the switching valve; one end of the third vacuum pipeline is connected with the third end of the switching valve, and the other end of the third vacuum pipeline is communicated with an atmosphere communication port of an activated carbon tank of a vehicle or is connected with an air inlet of a desorption control valve of the vehicle; the pressure sensor is arranged on the third vacuum pipeline;
the switching valve is used for being closed under the control of the ECU so as to enable the second vacuum pipeline and the third vacuum pipeline to be communicated, or being opened under the control of the ECU so as to enable the first vacuum pipeline and the third vacuum pipeline to be communicated; the pressure sensor is connected with the ECU;
the ECU is configured to: closing a desorption control valve of the vehicle when a preset fault detection enabling condition is detected; judging whether the pressure in the device is stable or not according to the value of the pressure sensor; when the pressure in the device is determined to be stable, recording the value in the pressure sensor as a first pressure value; opening the switching valve and opening the desorption control valve; after a preset time period, recording the numerical value of the pressure sensor as a second pressure value; and when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal.
In a second aspect, an embodiment of the present invention provides a desorption flow fault detection method for a vehicle evaporative emission system, which is applied to the desorption flow fault detection device for a vehicle evaporative emission system provided in the first aspect, and the method includes:
closing a desorption control valve of the vehicle when a preset fault detection enabling condition is detected;
judging whether the pressure in the device is stable or not according to the value of the pressure sensor;
when the pressure in the device is determined to be stable, recording the value in the pressure sensor as a first pressure value;
opening the switching valve to communicate the first vacuum line and the third vacuum line;
opening the desorption control valve;
after a preset time period, recording the numerical value of the pressure sensor as a second pressure value;
and when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal.
In a third aspect, the embodiment of the invention further provides a vehicle, which comprises the vehicle evaporative emission system desorption flow fault detection device provided in the first aspect.
The embodiment provides a vehicle evaporative emission system desorption flow fault detection device, a method and a vehicle, wherein the device comprises: the device comprises an ECU, a pressure sensor, an orifice, a switching valve, a first vacuum pipeline, a second vacuum pipeline and a third vacuum pipeline, wherein the diameter of the orifice is smaller than the inner diameter of the second vacuum pipeline, one end of the first vacuum pipeline is communicated with the atmosphere, the other end of the first vacuum pipeline is connected with the first end of the switching valve, the orifice is arranged on the first vacuum pipeline, one end of the second vacuum pipeline is communicated with the atmosphere, the other end of the second vacuum pipeline is connected with the second end of the switching valve, one end of the third vacuum pipeline is connected with the third end of the switching valve, the other end of the third vacuum pipeline is communicated with the atmosphere communication port of an activated carbon tank of a vehicle or is connected with an air inlet of a desorption control valve of the vehicle, the pressure sensor is arranged on the third vacuum pipeline, the switching valve is used for being closed under the control of the ECU so as to communicate the second vacuum pipeline with the third vacuum pipeline, or, open under ECU's control to make first vacuum line and third vacuum line communicate, pressure sensor is connected with ECU, ECU is used for: closing a desorption control valve of the vehicle when a preset fault detection enabling condition is detected; judging whether the pressure in the device is stable or not according to the value of the pressure sensor; when the pressure in the device is determined to be stable, recording the value in the pressure sensor as a first pressure value; opening the switching valve and opening the desorption control valve; after a preset time period, recording the value of the pressure sensor as a second pressure value; and when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal. On the one hand, through detecting the desorption control valve and opening the front and back, the degree of pressure decline in the third vacuum pipeline detects the desorption flow, compare in prior art, do not receive the shock characteristic influence of oil tank pressure, thereby, the accuracy of vehicle evaporation emission system desorption flow fault detection has been improved, on the other hand, open the desorption control valve after opening the diverter valve, through setting up the orifice on first vacuum pipeline, the realization is stepped down the desorption flow, the change volume of desorption flow around the desorption control valve is opened has been increased, thereby, the accuracy of vehicle evaporation emission system desorption flow fault detection has further been improved.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of a desorption flow fault detection device of a vehicle evaporative emission system provided by the invention;
fig. 2 is a schematic diagram of another implementation manner of a first vacuum pipeline and a second vacuum pipeline in a desorption flow fault detection device of a vehicle evaporative emission system provided by the invention;
FIG. 3A is a schematic view of the embodiment of FIG. 1 showing an installation manner of the desorption flow fault detection device of the vehicle evaporative emission system in the vehicle evaporative emission system;
FIG. 3B is a schematic view of another installation manner of the desorption flow fault detection device of the vehicle evaporative emission system in the embodiment shown in FIG. 1;
FIG. 4 is a schematic flow chart of a method for detecting a desorption flow fault of an evaporative emission system of a vehicle according to the present invention;
fig. 5 is a timing chart of the desorption flow fault detection signal in the embodiment shown in fig. 4.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic structural diagram of an embodiment of a desorption flow fault detection device of a vehicle evaporative emission system provided by the invention. Fig. 3A is a schematic diagram of an installation manner of the desorption flow fault detection device of the vehicle evaporative emission system in the embodiment shown in fig. 1. Fig. 3B is a schematic diagram of another installation manner of the desorption flow fault detection device of the vehicle evaporative emission system in the embodiment shown in fig. 1. The embodiment is suitable for a scene for detecting the desorption flow fault of the vehicle evaporative emission system. As shown in fig. 1, 3A and 3B, the present embodiment provides a desorption flow failure detection device for a vehicle evaporative emission system, including: an Electronic Control Unit (ECU) 30, a pressure sensor 56, an orifice 55, a switching valve 59, a first vacuum line 53, a second vacuum line 52, and a third vacuum line 58. The orifice 55 has a diameter smaller than the inner diameter of the second vacuum line 52.
One end of the first vacuum line 53 communicates with the atmosphere, and the other end of the first vacuum line 53 is connected to a first end of the switching valve 59. An orifice 55 is provided in the first vacuum line 53. One end of the second vacuum line 52 is connected to the atmosphere, and the other end of the second vacuum line 52 is connected to a second end of the switching valve 59. One end of the third vacuum line 58 is connected to a third end of the switching valve 59, and the other end of the third vacuum line 58 is connected to an atmosphere communication port of the canister 4 of the vehicle or to an air inlet of the desorption control valve 8 of the vehicle. A pressure sensor 56 is disposed on the third vacuum line.
The switching valve 59 is configured to be closed under the control of the ECU30 to communicate the second vacuum line 52 and the third vacuum line 58, or opened under the control of the ECU30 to communicate the first vacuum line 53 and the third vacuum line 58. The pressure sensor 56 is connected to the ECU 30.
The ECU30 is configured to: when a preset fault detection enabling condition is detected, closing the desorption control valve 8 of the vehicle; judging whether the pressure in the device is stable or not according to the value of the pressure sensor 56; when it is determined that the pressure in the device is stable, recording the value in the pressure sensor 56 as a first pressure value; the switching valve 59 is opened, and the desorption control valve 8 is opened; after a preset time period, recording the value of the pressure sensor 56 as a second pressure value; and when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal.
Specifically, the ECU30 in the present embodiment refers to a controller in a vehicle. The ECU may also be connected to an intake air pressure sensor 26, a crank position sensor 31, a vehicle speed sensor 32, a coolant water temperature sensor 33, an ambient temperature sensor 34, an upstream oxygen sensor 35, and an ambient pressure sensor 36 to monitor whether a fault detection enable condition has occurred.
As shown in fig. 3A and 3B, an engine intake system 200 of a vehicle includes a first air cleaner 20 connected to a supercharger 22, and the first air cleaner 20 is connected to the supercharger 22 through a first intake pipe 21. The air pressurized by the supercharger 22 is cooled in the intercooler 23 and then introduced into the intake manifold 27 of the intake pipe of the engine through the second intake pipe 24. An intake pressure sensor 26 is mounted downstream of the throttle valve 25 in the intake pipe. Downstream of the throttle valve 25 refers to a position in the throttle valve 25 where gas flows out.
The evaporative emission system 100 of a vehicle includes a fuel tank 1. One side of the oil tank 1 is connected with an oil filling pipe (not shown in the figure), and the other side of the oil tank 1 is connected with an air inlet port of an activated carbon tank 4 through a fourth vacuum pipeline 2. The activated carbon canister 4 is used to collect and store fuel vapor evaporated from the fuel tank 1. In the vehicle evaporative emission system desorption flow failure detection apparatus provided in the present embodiment, a combination of components other than the ECU30 is shown by reference numeral 5 in fig. 3A and 3B.
The desorption control valve 8 is provided with a second check valve 9 at the low-load desorption end and is connected to the intake manifold 27 through a seventh vacuum pipeline 14. The desorption control valve 8 is provided with a first one-way valve 10 at the high-load desorption end and is connected to the desorption port of the venturi tube 17 through an eighth vacuum pipeline 13. The desorption control valve 8 in this embodiment may be of an on-off control type or a periodic pulse control type. The high-pressure inlet port of the venturi 17 is connected to a second inlet line 24 after the intercooler 23 through a ninth vacuum line 16. The outlet port of the venturi 17 is communicated with a first inlet pipeline 21 in front of a supercharger 22 through a tenth vacuum tube 15.
The following two methods are used to install the desorption flow fault detection device in the vehicle.
In one implementation, referring to fig. 1 and fig. 3A, an atmosphere communication port of the activated carbon canister 4 is communicated with the other end of a third vacuum pipeline 58 in the desorption flow rate detection device disclosed in the present invention, one end of each of a first vacuum pipeline 53 and a second vacuum pipeline 52 in the desorption flow rate detection device disclosed in the present invention is connected to a second air cleaner 7 through a fifth vacuum pipeline 6, and the second air cleaner 7 is an air cleaner communicated with the atmosphere communication port of the activated carbon canister 4. In one embodiment, the atmosphere connection port of the activated carbon canister 4 may also be connected to the other end of the third vacuum line 58 in the desorption flow rate detection device through a vacuum line.
In this implementation, the outlet port of the activated carbon canister 4 is connected to the inlet port of the desorption control valve 8 through the sixth vacuum line 3.
In this implementation, one end of the first vacuum line 53 and one end of the second vacuum line 52 are both communicated with the atmosphere through the second air cleaner 7 in the vehicle, which is communicated with the atmosphere communication port of the canister 4, and the other end of the third vacuum line 58 is communicated with the atmosphere communication port of the canister 4.
In another implementation, referring to fig. 1 and fig. 3B, the atmosphere communication port of the activated carbon canister 4 is communicated with the second air cleaner 7 through a fifth vacuum line 6. One end of the first vacuum pipeline 53 and one end of the second vacuum pipeline 52 in the desorption flow detection device are communicated with the air outlet of the activated carbon tank 4. In one embodiment, the gas outlet of the activated carbon canister 4 may also be connected to one end of the first vacuum line 53 and the second vacuum line 52 of the desorption flow rate detection device through vacuum lines. The other end of the third vacuum pipeline in the desorption flow detection device is connected with the air inlet of the desorption control valve 8 through the sixth vacuum pipeline 3.
In this implementation, one end of the first vacuum line 53 and one end of the second vacuum line 52 communicate with the atmosphere through the air outlet of the activated carbon canister 4, the inner cavity of the activated carbon canister 4, the atmosphere communication port of the activated carbon canister 4, and the second air cleaner 7 in the vehicle that communicates with the atmosphere communication port of the activated carbon canister 4, and the other end of the third vacuum line 58 is connected to the air inlet of the desorption control valve 8.
The first vacuum line 53 and the second vacuum line 52 may be implemented in the following two ways.
In a first implementation, as shown in fig. 1, the first vacuum line 53 and the second vacuum line 52 meet at a certain position, and then become a vacuum line to communicate with the atmosphere. In this implementation, an orifice 55 is provided in the first vacuum line 53 before it meets the second vacuum line 52, with the flow of air in the first vacuum line 53 being indicated by arrow L and the flow of air in the second vacuum line 52 being indicated by arrow M.
In a second implementation manner, fig. 2 is a schematic diagram of another implementation manner of a first vacuum pipeline and a second vacuum pipeline in a desorption flow fault detection device of a vehicle evaporative emission system provided by the invention. As shown in fig. 2, one end of the first vacuum line 53 and one end of the second vacuum line 52 are respectively communicated with the atmosphere. The air in the first vacuum line 53 flows as indicated by arrow N and the air in the second vacuum line 52 flows as indicated by arrow P.
An orifice 55 is provided in the first vacuum line 53 in this embodiment, and the diameter of the orifice 55 is smaller than the inner diameter of the second vacuum line 52. Illustratively, the diameter of the orifice 55 is much smaller than the inner diameter of the second vacuum line 52, e.g., the inner diameter of the second vacuum line 52 is from 5 times to 20 times the size of the diameter of the orifice 55. The throttle hole 55 in the present embodiment may be a plate-like structure with a through hole.
When the engine of the vehicle is running, the ECU30 may control the desorption control valve 8 to open to perform the desorption process of the fuel vapor adsorbed in the canister 4.
When the engine is operated in a supercharging mode, the supercharger 22 is operated to supercharge the air entering from the first air cleaner 20, and a pressure difference is generated between the first air intake pipe 21 and the second air intake pipe 24: the air pressure in the first intake pipe 21 is small and the air pressure in the second intake pipe 24 is large. A top-to-bottom airflow is generated in the venturi 17, and the desorption port of the venturi 17 generates a negative pressure based on the characteristics of the venturi 17.
With respect to the installation manner in fig. 3A, the negative pressure may cause air to enter the fifth vacuum line 6, the first vacuum line 53 or the second vacuum line 52 (the second vacuum line 52 when the switching valve 59 is closed; the first vacuum line 53 when the switching valve 59 is open), the switching valve 59, the third vacuum line 58 and the atmosphere communication port of the activated carbon canister 4 from the second air cleaner 7, and when an air flow formed by the air enters the inner cavity of the activated carbon canister 4, the fuel vapor adsorbed on the activated carbon canister may enter the engine through the air outlet port of the activated carbon canister 4, the sixth vacuum line 3, the desorption control valve 8, the first check valve 10, the venturi 17, the ninth vacuum line 16, the second air inlet line 24, the throttle valve 25 and the air inlet manifold 27 with the air flow, and the desorption process is completed.
With respect to the installation manner in fig. 3B, the negative pressure generated at the desorption port of the venturi tube 17 may cause air to enter the fifth vacuum line 6 and the atmosphere communication port of the canister 4 from the second air cleaner 7. When the airflow formed by the air enters the inner cavity of the activated carbon canister 4, the fuel vapor adsorbed on the activated carbon canister passes through the air outlet port of the activated carbon canister 4, the sixth vacuum pipeline 3, the first vacuum pipeline 53 or the second vacuum pipeline 52 (the second vacuum pipeline 52 when the switching valve 59 is closed; the first vacuum pipeline 53 when the switching valve 59 is open), the switching valve 59, the third vacuum pipeline 58, the sixth vacuum pipeline 3, the desorption control valve 8, the first check valve 10, the venturi tube 17, the ninth vacuum pipeline 16, the second air inlet pipeline 24, the throttle valve 25 and the air inlet manifold 27 along with the airflow, and finally enters the engine to complete the desorption process.
In the above process, the pipeline formed by the desorption control valve 8, the first check valve 10 and the venturi tube 17 is a high-load desorption pipeline.
When the engine is operating in a non-supercharging condition, a negative pressure is created within the intake manifold 27.
In the installation manner shown in fig. 3A, the negative pressure may cause air to enter the fifth vacuum line 6, the first vacuum line 53 or the second vacuum line 52 (the second vacuum line 52 when the switching valve 59 is closed; the first vacuum line 53 when the switching valve 59 is open), the switching valve 59, the third vacuum line 58 and the atmosphere communication port of the activated carbon canister 4 from the second air cleaner 7, and when an air flow formed by the air enters the inner cavity of the activated carbon canister 4, the fuel vapor adsorbed on the activated carbon canister may enter the engine through the air outlet port of the activated carbon canister 4, the sixth vacuum line 3, the desorption control valve 8, the second check valve 9, the seventh vacuum line 14 and the intake manifold 27 along with the air flow, and the desorption process is completed.
With the installation in fig. 3B, the negative pressure generated in the intake manifold 27 may cause air from the second air cleaner 7 to enter the fifth vacuum line 6 and the atmosphere communication port of the canister 4. When the airflow formed by the air enters the inner cavity of the activated carbon canister 4, the fuel vapor adsorbed on the activated carbon canister passes through the air outlet port of the activated carbon canister 4, the sixth vacuum pipeline 3, the first vacuum pipeline 53 or the second vacuum pipeline 52 (the second vacuum pipeline 52 when the switching valve 59 is closed; the first vacuum pipeline 53 when the switching valve 59 is open), the switching valve 59, the third vacuum pipeline 58, the sixth vacuum pipeline 3, the desorption control valve 8, the second check valve 9, the seventh vacuum pipeline 14 and the intake manifold 27 along with the airflow, and finally enters the engine to complete the desorption process.
In the above process, the desorption control valve 8 and the second check valve 9 form a low-load desorption pipeline.
In the fuel steam desorption process, the airflow flows from the A end to the B end of the desorption flow fault detection device of the vehicle evaporative emission system. When the switching valve 59 is closed, the gas flows through the second vacuum line 52, the switching valve 59, and the third vacuum line 58; when the switching valve 59 is open, the gas flow is routed through the first vacuum line 53, the switching valve 59, and the third vacuum line 58. Since the orifice 55 is provided in the first vacuum line 53 and the diameter of the orifice 55 is smaller than the inner diameter of the second vacuum line 52, the orifice 55 exerts a pressure reducing and flow restricting effect on the air flow, and the air resistance of the passage through which the air flow passes increases and the pressure in the third vacuum line 58 decreases during the period from closing to opening of the switching valve 59. The present embodiment can detect the desorption flow rate by detecting the degree of pressure drop in the third vacuum line 58 before and after the desorption control valve 8 is opened.
Fig. 4 is a schematic flow chart of a desorption flow fault detection method for a vehicle evaporative emission system provided by the invention. The present embodiment may be implemented by a vehicle evaporative emission system desorption flow fault detection device, which may be implemented by means of software and/or hardware, and which may be integrated in an ECU of a vehicle. The method provided by the embodiment can be applied to the embodiment of the desorption flow fault detection device of the vehicle evaporative emission system and various optional embodiments. As shown in fig. 4, the method for detecting a desorption flow fault of a vehicle evaporative emission system provided by the embodiment includes the following steps:
step 401: when a preset fault detection enabling condition is detected, the desorption control valve of the vehicle is closed.
Specifically, when no detection is performed, the desorption control valve 8 is in an open state, the switching valve 59 is in a closed state, and the second vacuum line 52 and the third vacuum line 58 are communicated.
The fault detection enable condition includes the following sub-conditions: the engine speed is between 1200 rpm and 5000 rpm, the vehicle speed is between 20 km/h and 160 km/h, the ambient temperature is greater than 3 degrees celsius, the engine is operating in a preset operating temperature range, the engine is operating in a closed-loop fuel control state, and the absolute value of the difference between the intake pressure and the ambient pressure is greater than 5 kpa. In this embodiment, when the sub-conditions included in the fault detection enabling condition are simultaneously satisfied, the desorption flow fault detection is started.
It should be noted that the fault detection enable condition may also include other sub-conditions, and the embodiment is not limited thereto.
Referring to fig. 3A or 3B, ECU30 may determine the engine speed via crank position sensor 31, vehicle speed via vehicle speed sensor 32, ambient temperature via ambient temperature sensor 34, engine operating temperature via coolant water temperature sensor 33, whether the engine is operating in a closed-loop fuel control state via upstream oxygen sensor 35, and the difference between intake pressure and ambient pressure based on intake pressure sensor 26 and ambient pressure sensor 36.
When the rotating speed of the engine is between 1200 rpm and 5000 rpm, or the vehicle speed is between 20 kilometers per hour and 160 kilometers per hour, the working condition of the engine is stable, and the desorption pressure source is stable. When the desorption pressure source is stable, the detection accuracy of the desorption flow fault is higher. If the ambient temperature is too low, for example, below 3 degrees celsius, no fuel vapor escapes from the fuel tank 1, and desorption flow failure detection is not necessary. If the engine is not operating in a closed loop fuel control state, detecting a desorption flow fault may affect vehicle emissions. If the absolute value of the difference between the intake pressure and the ambient pressure is small, for example, less than 5 kpa, the detection accuracy of the desorption flow rate failure is low.
When the failure detection enabling condition is satisfied, the detection program in the ECU takes over the control authority of the desorption control valve 8 and the switching valve 59.
Step 402: and judging whether the pressure in the device is stable or not according to the value of the pressure sensor.
Specifically, after the desorption control valve 8 is closed, since the negative pressure during desorption does not exist, the pressure in the third vacuum line 58 is restored to the atmospheric pressure. And judging whether the pressure in the desorption flow fault detection device of the vehicle evaporative emission system is stable or not according to the value of the pressure sensor 56. Specifically, it may be determined whether a difference between values of the front and rear pressures corresponding to the front and rear sampling times is smaller than a preset threshold value within a preset time period, and when the difference is smaller than the preset threshold value, it is determined that the pressure in the apparatus is stable.
In a specific implementation, step 402 may be performed while a pressure stabilization timer is activated, and the timer starts to count time after step 402 is entered. If the pressure in the device is not stable, determining if the pressure stability timer has reached a limit T1, and if the pressure stability timer has not reached a limit T1, continuing to return to step 402; when the pressure stabilization timer reaches the limit T1, the timer is cleared and the process proceeds to step 403.
Step 403: when it is determined that the pressure in the device is stable, the value in the pressure sensor is recorded as a first pressure value.
Step 404: and opening the switching valve to communicate the first vacuum pipeline and the third vacuum pipeline.
Specifically, the first pressure value is counted as Pref. After the first pressure value is recorded, the switching valve 59 is opened to communicate the first vacuum line 53 and the third vacuum line 58.
Step 405: the desorption control valve is opened.
In one embodiment, the desorption control valve 8 is an on-off valve, in which step the ECU30 may open the desorption control valve. In one embodiment, the desorption control valve 8 is a pulsed duty cycle type valve in which the ECU30 may open the desorption control valve at 100% duty cycle.
In this embodiment, the opening degree of the desorption control valve 8 is not limited, and only after the desorption control valve 8 is opened, the desorption gas flows through.
Step 406: and after the preset time period, recording the value of the pressure sensor as a second pressure value.
Specifically, after the desorption control valve 8 is opened, the desorption gas flow may cause a significant pressure drop at the orifice 55. In this embodiment, in order to improve the detection accuracy, after a preset time period, the value of the pressure sensor 56 is recorded as the second pressure value Pcheck. The preset time period may be 1 second to 5 seconds.
Step 407: and when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal.
If the amplitude of the pressure drop exceeds the pressure difference threshold after the desorption control valve 8 is opened, namely Pcheck < Pref-Pthd, the desorption airflow is normally communicated and the desorption flow is normal. Illustratively, the pressure difference threshold Pthd may be any value between 0.5 kpa and 3 kpa.
After determining that the desorption flow rate is normal, the ECU30 may close the desorption control valve 8 first and then close the switching valve 59 to end the desorption flow rate fault detection. If the ECU closes the switching valve first and then closes the desorption control valve, the evaporative emission system of the vehicle may generate a large negative pressure and even the oil tank may deform.
Step 408: and when the difference value between the first pressure value and the second pressure value is smaller than or equal to the pressure difference threshold value, determining that the desorption flow is abnormal.
Specifically, when Pcheck is greater than or equal to Pref-Pthd, it indicates that the path of the desorption gas flow is abnormal, so the magnitude of the pressure drop is low, i.e., the desorption flow rate is abnormal.
Optionally, in this implementation, before step 402, the method further includes: and judging whether the engine of the vehicle is in a supercharging working condition or not according to the value of the air inlet pressure sensor. Optionally, when the value of the intake pressure sensor is greater than a preset pressure threshold value, the engine is in a supercharging working condition; when the value of the intake pressure sensor is smaller than or equal to the preset pressure threshold value, the engine is in a non-supercharging working condition. Accordingly, based on this implementation, after step 408, further comprising: when the engine is determined to be in a supercharging working condition, determining that a high-load desorption pipeline formed by the desorption control valve 8, the first one-way valve 10 and the venturi tube 17 breaks down; when the engine is determined to be in the non-supercharging working condition, the low-load desorption pipeline formed by the desorption control valve 8 and the second one-way valve 9 is determined to be in fault.
When the engine is in a supercharging working condition, the pipeline through which the desorption flow flows is a high-load desorption pipeline, and if the desorption flow is detected to be abnormal, the high-load desorption pipeline is indicated to be in fault, namely, the high-load desorption pipeline is blocked or disconnected. When the engine is in a non-supercharging working condition, the pipeline through which the desorption flow flows is a low-load desorption pipeline, and if the desorption flow is detected to be abnormal, the low-load desorption pipeline is indicated to be in fault, namely, the low-load desorption pipeline is blocked or disconnected.
Fig. 5 is a timing chart of the desorption flow fault detection signal in the embodiment shown in fig. 4. The desorption flow rate detection routine is executed after the engine is started, indicates that the fault detection enabling condition is not satisfied, and detects whether the fault detection enabling condition is satisfied or not. When the fault detection enabling condition is satisfied, the detection program obtains the control right of the desorption control valve 8 and the switching valve 59, and closes the desorption control valve 8 in step 401. ③ represents judging at step 402 whether the pressure of the evaporation system, i.e. the pressure in the desorption flow fault detection device is stable and judging whether the pressure stability timer reaches the limit value T1. And represents that when the evaporation system pressure stabilizes or the pressure stabilization timer has reached the limit value T1, the value of the pressure sensor 56 at this time is recorded as Pref at step 403, and the switching valve 59 is opened at step 404. After the switching valve 59 is opened, the desorption control valve 8 is opened in step 405. In one embodiment, the pulsed duty cycle desorption control valve 8 may be opened to 100% open. The value of the pressure sensor 56 after the desorption control valve 8 is opened is recorded in step 406, and it is judged in step 407 whether or not the pressure change in the device exceeds the threshold value.
If the desorption flow rate of the evaporative emissions system is normal, the signal of the pressure sensor 56 and the detection result flag are indicated by the solid line in fig. 5, and it is indicated by the fact that the pressure change of the evaporative emissions system exceeds the pressure difference threshold value in step 407, and the desorption control valve 8 and the switching valve 59 are closed to confirm the normal detection result of the desorption flow rate. And sixthly, the control right of the desorption control valve 8 and the switching valve 59 is released in the desorption flow detection program, and the detection program is ended.
If the desorption flow rate of the evaporative emissions system is abnormal, the signal of the pressure sensor 56 and the detection result flag are partially shown by the dotted line in fig. 5, and it is calculated in step 408 that the pressure change of the evaporative emissions system does not exceed the pressure difference threshold and the malfunction delay timer exceeds the maximum limit value T2, and it is confirmed that the desorption flow rate detection result is abnormal, and the desorption control valve 8 and the switching valve 59 are closed. And sixthly, the control right of the desorption control valve 8 and the switching valve 59 is released in the desorption flow detection program, and the detection program is ended.
The vehicle evaporative emission system desorption flow fault detection device that this embodiment provided includes: the device comprises an ECU, a pressure sensor, an orifice, a switching valve, a first vacuum pipeline, a second vacuum pipeline and a third vacuum pipeline, wherein the diameter of the orifice is smaller than the inner diameter of the second vacuum pipeline, one end of the first vacuum pipeline is communicated with the atmosphere, the other end of the first vacuum pipeline is connected with the first end of the switching valve, the orifice is arranged on the first vacuum pipeline, one end of the second vacuum pipeline is communicated with the atmosphere, the other end of the second vacuum pipeline is connected with the second end of the switching valve, one end of the third vacuum pipeline is connected with the third end of the switching valve, the other end of the third vacuum pipeline is communicated with the atmosphere communication port of an activated carbon tank of a vehicle or is connected with an air inlet of a desorption control valve of the vehicle, the pressure sensor is arranged on the third vacuum pipeline, the switching valve is used for being closed under the control of the ECU so as to communicate the second vacuum pipeline with the third vacuum pipeline, or, open under ECU's control to make first vacuum line and third vacuum line communicate, pressure sensor is connected with ECU, ECU is used for: closing a desorption control valve of the vehicle when a preset fault detection enabling condition is detected; judging whether the pressure in the device is stable or not according to the value of the pressure sensor; when the pressure in the device is determined to be stable, recording the value in the pressure sensor as a first pressure value; opening the switching valve and opening the desorption control valve; after a preset time period, recording the value of the pressure sensor as a second pressure value; and when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal. On the one hand, through detecting the desorption control valve and opening the front and back, the degree of pressure decline in the third vacuum line detects the desorption flow, compare in prior art, do not receive the shock characteristic influence of oil tank pressure, thereby, the accuracy that vehicle evaporation emission system desorption flow fault detected has been improved, on the other hand, through setting up the orifice on first vacuum line, the desorption flow after opening the desorption control valve steps down, the change volume of desorption flow around the desorption control valve was opened has been increased, thereby, the accuracy that vehicle evaporation emission system desorption flow fault detected has further been improved.
The invention also provides a vehicle which comprises the vehicle evaporative emission system desorption flow fault detection device provided in the embodiment shown in the figure 1 and various optional implementation modes.
The present invention also provides a storage medium containing computer executable instructions which, when executed by a computer processor, are operable to perform a method of vehicle evaporative emission system desorption flow fault detection, the method comprising:
closing a desorption control valve of the vehicle when a preset fault detection enabling condition is detected;
judging whether the pressure in the device is stable or not according to the value of the pressure sensor;
when the pressure in the device is determined to be stable, recording the value in the pressure sensor as a first pressure value;
opening the switching valve to communicate the first vacuum line and the third vacuum line;
opening the desorption control valve;
after a preset time period, recording the numerical value of the pressure sensor as a second pressure value;
and when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal.
Of course, the storage medium provided by the embodiment of the invention contains the computer-executable instructions, and the computer-executable instructions are not limited to the operation of the method described above, and can also execute the relevant operation in the desorption flow fault detection method of the vehicle evaporative emission system provided by any embodiment of the invention.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (8)
1. A vehicle evaporative emission system desorption flow fault detection device, comprising: the device comprises an electronic control unit ECU, a pressure sensor, an orifice, a switching valve, a first vacuum pipeline, a second vacuum pipeline and a third vacuum pipeline, wherein the diameter of the orifice is smaller than the inner diameter of the second vacuum pipeline;
one end of the first vacuum pipeline is communicated with the atmosphere, the other end of the first vacuum pipeline is connected with the first end of the switching valve, and the throttling hole is arranged on the first vacuum pipeline; one end of the second vacuum pipeline is communicated with the atmosphere, and the other end of the second vacuum pipeline is connected with the second end of the switching valve; one end of the third vacuum pipeline is connected with the third end of the switching valve, and the other end of the third vacuum pipeline is communicated with an atmosphere communication port of an activated carbon tank of a vehicle or is connected with an air inlet of a desorption control valve of the vehicle; the pressure sensor is arranged on the third vacuum pipeline;
the switching valve is used for being closed under the control of the ECU so as to enable the second vacuum pipeline and the third vacuum pipeline to be communicated, or being opened under the control of the ECU so as to enable the first vacuum pipeline and the third vacuum pipeline to be communicated; the pressure sensor is connected with the ECU;
the ECU is configured to: closing a desorption control valve of the vehicle when a preset fault detection enabling condition is detected; judging whether the pressure in the device is stable or not according to the value of the pressure sensor; when the pressure in the device is determined to be stable, recording the value in the pressure sensor as a first pressure value; opening the switching valve and opening the desorption control valve; after a preset time period, recording the numerical value of the pressure sensor as a second pressure value; when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal;
the one end of first vacuum pipeline and the one end of second vacuum pipeline pass through the gas outlet of active carbon jar the inner chamber of active carbon jar the atmosphere intercommunication port of active carbon jar and in the vehicle with the air cleaner and the atmosphere intercommunication of the atmosphere intercommunication port intercommunication of active carbon jar, the other end of third vacuum pipeline with the air inlet of desorption control valve is connected.
2. The apparatus of claim 1, wherein the second vacuum line has an inner diameter that is between 5 and 20 times the size of the diameter of the orifice.
3. A desorption flow fault detection method for a vehicle evaporative emission system, which is applied to a desorption flow fault detection device for a vehicle evaporative emission system according to any one of claims 1 to 2, and comprises the following steps:
closing a desorption control valve of the vehicle when a preset fault detection enabling condition is detected;
judging whether the pressure in the device is stable or not according to the value of the pressure sensor;
when the pressure in the device is determined to be stable, recording the value in the pressure sensor as a first pressure value;
opening the switching valve to communicate the first vacuum pipeline with the third vacuum pipeline;
opening the desorption control valve;
after a preset time period, recording the numerical value of the pressure sensor as a second pressure value;
and when the difference value between the first pressure value and the second pressure value is larger than a preset pressure difference threshold value, determining that the desorption flow is normal.
4. The method of claim 3, further comprising:
and when the difference value between the first pressure value and the second pressure value is smaller than or equal to the pressure difference threshold value, determining that the desorption flow is abnormal.
5. The method of claim 4, wherein before determining whether the pressure in the device is stable based on the value of the pressure sensor, the method further comprises:
judging whether an engine of the vehicle is in a supercharging working condition or not according to the value of the air inlet pressure sensor;
accordingly, after determining that the desorption flow rate is abnormal, the method further comprises:
when the engine is determined to be in a supercharging working condition, determining that a high-load desorption pipeline formed by the desorption control valve, the first one-way valve and the venturi tube breaks down;
and when the engine is determined to be in a non-supercharging working condition, determining that a low-load desorption pipeline formed by the desorption control valve and the second one-way valve has a fault.
6. The method according to any one of claims 3 to 5, wherein after determining that the desorption flow rate is normal, the method further comprises:
and closing the desorption control valve and closing the switching valve.
7. The method according to any of claims 3-5, wherein the fault detection enabling condition comprises:
the engine speed is between 1200 and 5000 revolutions per minute;
the vehicle speed is between 20 kilometers per hour and 160 kilometers per hour;
the ambient temperature is more than 3 ℃;
the engine operates in a preset working temperature range;
the engine operating in a closed loop fuel control state; and the number of the first and second groups,
the absolute value of the difference between the intake pressure and the ambient pressure is greater than 5 kilopascals.
8. A vehicle characterized by comprising a vehicle evaporative emission system desorption flow failure detection device as claimed in any one of claims 1-2.
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| CN110821693A (en) * | 2019-11-04 | 2020-02-21 | 中国第一汽车股份有限公司 | Fault detection method and system for desorption control valve of fuel evaporation and discharge system |
| CN111103148B (en) * | 2019-12-18 | 2021-11-30 | 中国第一汽车股份有限公司 | Jam detection method and vehicle |
| KR20210083785A (en) * | 2019-12-27 | 2021-07-07 | 현대자동차주식회사 | leak diagnosis system using purge pump of active purge system and leak diagnosis method using purge pump of active purge system |
| CN112627956B (en) * | 2020-12-14 | 2022-07-15 | 北汽福田汽车股份有限公司 | Differential pressure pipe cleaning system of vehicle and vehicle with same |
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