Method and device for obtaining flow through a timing valve
By detecting the pressure and temperature upstream of the timing valve, calculating the flow rate and adjusting the model, the problem of inaccurate flow measurement in the prior art is solved, and high-accurate flow determination is achieved to prevent combustion chamber deviation and increase internal combustion engine emissions.
Patent Information
- Application Number
- CN202080070730.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2019-10-09
- Filing Date
- 2020-09-07
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2040-09-07
AI Technical Summary
The prior art is difficult to accurately measure the flow rate of the motor vehicle material box bleed valve, resulting in combustion chamber mixture deviation and internal combustion engine emissions, and it is impossible to consider system characteristics changes caused by aging and component tolerances.
By detecting the pressure, temperature, and volume upstream of the timing valve, obtaining flow and comparing it with the modeled flow, adjusting the flow model to account for aging and tolerances, calculating the flow using pressure gradients and gas constants to ensure high accuracy of the flow.
Long-term high accuracy of flow determination is achieved to prevent combustion chamber mixture deviations and internal combustion engine emissions from increasing, adaptation factors are used to adjust the model to optimize flow calculations.
Smart Images
Figure CN114450477B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method and a device for detecting a flow through a timing valve, in particular a timing valve of a motor vehicle. In particular, the timing valve can be a tank vent valve. Background Art
[0002] In gasoline-engine-driven motor vehicles, fuel gas is led from the fuel tank via a tank bleed line, temporarily stored in an adsorption filter and then supplied to the gasoline-driven internal combustion engine via a tank bleed valve. The fuel gas that leaves the tank for pressure equalization can thus be captured and subsequently further utilized, which reduces losses. Due to the untreated emissions of the engine, it is necessary to operate the engine at a stoichiometric air-fuel ratio. For this purpose, the fuel injection quantity must be corrected to the fuel gas quantity supplied via the tank bleed. In order to be able to carry out this fuel injection quantity correction, the flow through the tank bleed valve must be acquired.
[0003] It is known to determine this flow by measuring the tank bleed system and to make it available to the engine control as a calibration value or as a data model. However, such a measurement of the tank bleed system is laborious. Furthermore, neither changes in system characteristics due to aging nor machining tolerances in components, that is to say in particular in valves, can be taken into account. As a result, the accuracy of the injection correction is impaired, which can lead to mixture deviations in the combustion chamber and thus to increased emissions of the internal combustion engine. Summary of the invention
[0004] The invention is based on the object of providing a method and a device for detecting a flow through a timing valve, which method and device also allow the flow to be determined with high accuracy over a long period of time. This object is achieved by a method according to claim 1 and by a device according to claim 12. Advantageous embodiments are the subject of the dependent claims, the description and the drawings.
[0005] The method for obtaining the flow through the timing valve according to the present invention comprises the following steps:
[0006] - detecting the pressure upstream of the timing valve during venting of a container arranged upstream of the timing valve;
[0007] - obtaining the flow rate through the timing valve according to the pressure detected upstream of the timing valve and according to the temperature and volume of the gas in the container;
[0008] - comparing the flow rate acquired during said exhaust with a modelled flow rate and / or comparing quantities related to the acquired flow rate with quantities related to the modelled flow rate;
[0009] - When a deviation occurs between the acquired flow rate and the modeled flow rate during the exhaust, and / or when a deviation occurs between a quantity related to the acquired flow rate and a quantity related to the modeled flow rate, adjusting the model.
[0010] In the method according to the invention, an existing model of the flow through the timing valve is adjusted or corrected, that is, on the basis of the flow through the timing valve (the flow is present during the exhaust of the container upstream of the timing valve). The model can be derived. The step of modeling the flow through the timing valve and / or the step of modeling the quantity related to the flow can also be preset as part of the method. Possible models are then elaborated in detail. As explained at the beginning, the flow modeled by the model may have errors, which are due to the aging of system components and due to component tolerances.
[0011] Therefore, according to the invention, during the exhaust of the container arranged upstream of the timing valve, the pressure upstream of the timing valve is obtained. The pressure is obtained in particular during the entire period of exhaust. Therefore, the pressure gradient can be determined. The flow through the timing valve during the exhaust is then obtained from the pressure or the pressure gradient, and from the temperature and volume of the gas in the container. During the exhaust, the possible flow to the system, in particular to the container, is preferably closed. Then, the flow obtained during the exhaust is compared with the modeled flow. It is also possible to compare between the quantity related to the obtained flow and the quantity related to the modeled flow. Such a related quantity can be, for example, the flow rate (Durchflussmenge), that is, the mass that flows through the timing valve in a specific time period, in particular in the entire exhaust time period.
[0012] If this comparison results in a deviation between the acquired flow and the modeled flow, or a deviation between quantities related thereto, the model on which the modeled flow is based is adjusted accordingly. Thus, the flow model can be rationalized and, if necessary, adjusted. For example, the deviation can be retained in an adaptation factor and henceforth taken into account when calculating the flow through the tank venting valve. Thus, component aging and component tolerances can be taken into account in a simple manner. If the timing valve is used as a tank venting valve for a motor vehicle, mixture deviations in the combustion chamber can be prevented by means of the method according to the invention, in particular over the entire life of the system, and thus an increase in emissions of the internal combustion engine can be prevented.
[0013] According to the design solution, the flow rate through the timing valve during exhaust is obtained according to the following relationship:
[0014]
[0015] in:
[0016] is the flow rate through the timing valve,
[0017] is the volume of the gas in the container,
[0018] is the specific gas constant of the gas in the container,
[0019] is the temperature of the gas in the container,
[0020] is the pressure gradient in the vessel.
[0021] As can be directly inferred from the relationship, the flow through the timing valve is therefore determined based on the detected pressure, ie, the pressure gradient, and on the temperature and volume in the container. In particular, the container can be a fuel tank of a motor vehicle.
[0022] According to the design, the flow rate through the timing valve that flows in a preset time period is determined by the flow rate acquired during the exhaust. The flow rate is a quantity related to the acquired flow rate. The flow rate can also be called mass flow, and the flow rate can also be called mass. Then, in particular, a comparison can be made between the acquired flow rate and the modeled flow rate, and when a deviation occurs between these flow rates, the model on which the modeled flow rate is based is adjusted.
[0023] In particular, the flow rate can be determined according to the following relationship:
[0024]
[0025] in,
[0026] is the flow rate through the timing valve, and
[0027] is from t0 to t ende The flow rate that has flowed through the timing valve during the time period.
[0028] In this case, the time t0 in particular represents the start of the venting process of the container, and the time t ende Indicates the end of the exhaust process of the container. Therefore, the amount of gas leaking from the tank during the entire exhaust process can be determined.
[0029] According to a design solution, one or more of the following parameters are set in the model on which the modeled flow is based: the pressure detected upstream of the timing valve, the pressure detected downstream of the timing valve, the flow cross-sectional area of the timing valve, the acquired opening time of the timing valve, and the acquired closing time of the timing valve. According to a design solution related to this, the modeling of the flow through the timing valve can be achieved in particular by acquiring the flow through the timing valve, taking into account the pressure detected upstream of the timing valve, the pressure detected downstream of the timing valve, the acquired opening time of the timing valve, and the acquired closing time of the timing valve.
[0030] According to the design scheme related thereto, the following relationship can be used to model the flow through the timing valve:
[0031]
[0032] in,
[0033] is the flow rate through the timing valve,
[0034] is the reduced flow cross-sectional area of the timing valve,
[0035] is the flow parameter,
[0036] is the pressure detected downstream of the timing valve,
[0037] is the pressure detected upstream of the timing valve,
[0038] is the isentropic exponent of the mass flow through the timing valve, and
[0039] is the gas specific constant for the mass flow rate through the timing valve.
[0040] The superscript “TEV” here stands for a tank vent valve. As mentioned at the outset, the timing valve can in particular be such a tank vent valve.
[0041] According to the design scheme, the mentioned flow parameters can be determined according to the following relationship:
[0042]
[0043] in, is the critical pressure ratio.
[0044] According to the design, the method comprises the following steps: modeling of the flow through the timing valve and / or modeling of a quantity related to the flow (as already mentioned). The modeling can be implemented according to any of the above-explained relationships. The quantity related to the flow can particularly relate to the flow rate. The modeling step can be performed before the acquisition of the flow according to the invention. The modeling can also be performed in parallel therewith.
[0045] According to the embodiment, the venting of the container is achieved by a scavenging pump arranged between the container and the timing valve or by a negative pressure in an intake line section arranged downstream of the timing valve. During the venting, the inlet which would allow pressure equalization in the container is preferably closed. In particular, the supply of fresh air to the container via a shut-off valve is prevented.
[0046] According to a configuration, the pressure upstream of the timing valve is detected during the exhaust by means of a pressure sensor which is arranged upstream of the timing valve, for example in the container or in a line extending between the container and the timing valve.
[0047] According to one embodiment, the timing valve is a tank air release valve (as already explained).
[0048] Furthermore, the invention relates to a device for acquiring the flow through the timing valve, comprising a control unit, which is configured to implement the method described above. The descriptions made in connection with the method apply accordingly to the device. The device can then, for example, have a pressure sensor upstream of the timing valve for acquiring the pressure during the venting of the container. BRIEF DESCRIPTION OF THE DRAWINGS
[0049] The present invention is described below with reference to the accompanying drawings.
[0050] Figure 1 A device for carrying out the method according to the invention is shown, and
[0051] Figure 2 A diagram showing the pressure curve or the mass flow through the timing valve.
[0052] Unless otherwise stated, the same reference numerals below refer to the same objects. DETAILED DESCRIPTION
[0053] Figure 1 The device according to the invention is shown in an exemplary embodiment in which a flow through a tank venting valve of a motor vehicle is detected and regulated. Figure 1 The device in the embodiment constitutes a tank bleed system with a fuel tank 6 as a container. An activated carbon container 1 is connected to the fuel tank 6, to which fresh air is supplied via an air filter 9 through a shut-off valve 7. In addition, the activated carbon container 1 is connected to a tank bleed valve 5 via an optionally pre-set scavenging pump 2. A pressure sensor 3 is arranged in the pipeline between the scavenging pump 2 and the tank bleed valve 5. In the absence of a scavenging pump 2, the pressure sensor 3 is arranged between the activated carbon container 1 and the tank bleed valve 5. Upstream of the tank bleed valve 5, another pressure sensor 8 is arranged in the fuel tank 6. In addition, upstream of the tank bleed valve 5, there is another pressure sensor 4 before the scavenging pump 2. Downstream of the tank bleed pump 5, there is an intake pipe section 10 together with a compressor 11 and an air filter 9.
[0054] The mass flow from the fuel tank 6 to the tank purge valve 5 is guided downstream of the tank purge valve 5 into the intake line section 10 and mixed there with the fresh air to be compressed, which is supplied to the intake line section 10 via the air filter 9. The compressor 11 can be a component of an exhaust gas turbocharger.
[0055] In order to control the combustion process, the engine control unit 12 is configured as a control unit, which provides an output signal 21 based on the input signal 20 supplied to it and the stored operating software. The input signal 20 supplied to the engine control unit 12 can be in particular a sensor signal and / or a data signal provided by a higher-level control unit. Examples of the sensor signals are pressure sensor signals, temperature sensor signals and accelerator pedal position signals. The output signals 21 are in particular control signals for injection valves and the tank venting valve 5.
[0056] The flow through the tank vent valve 5 is first calculated with the aid of a physical model, in particular according to the following relationship:
[0057]
[0058] in,
[0059] is the flow through the tank bleed valve,
[0060] is the reduced cross-sectional area of the tank vent valve through which flow occurs,
[0061] is the flow parameter,
[0062] is the pressure detected downstream of the tank vent valve,
[0063] is the pressure detected upstream of the tank vent valve,
[0064] is the isentropic exponent of the mass flow through the tank bleed valve, and
[0065] is the gas constant specific to the mass flow rate through the tank bleed valve.
[0066] The following flow parameters may be applied in particular:
[0067]
[0068] in,
[0069] is the critical pressure ratio.
[0070] Therefore, in particular the pressure measured at the sensor 3 and geometrical dimensions, such as the flow cross-sectional area of the tank venting valve 5, are important input parameters. Such models are always subject to certain assumptions and do not necessarily accurately reproduce the actual flow through the tank venting valve. Thus, for example, the flow area can change over time due to aging of components.
[0071] Therefore, in order to rationalize the model and, if necessary, to adjust the model, according to the invention, in a first step, the change in state of the gas in the fuel tank 6, i.e., in particular the change in pressure and / or temperature, is observed during the venting of the fuel tank 6. Thus, the venting of the tank 6 is carried out, for example, by means of an electric scavenging pump 2 or as a function of a pressure drop across the tank venting valve 5 generated in another way, for example, in particular by means of a negative pressure in the intake line section 10. In this case, the supply of fresh air to the fuel tank 6 via the shut-off valve 7 is inhibited.
[0072] During the venting of the fuel tank 6, the pressure upstream of the tank vent valve 5 is detected by evaluating the data of the pressure sensor 8 in the tank 6. Thus, the pressure gradient is detected during the time period of the venting process. From the detected pressure / pressure gradient, the flow from the fuel tank 6 to the intake line section 10 through the tank vent valve 5 is then obtained. For this purpose, the following relationship can be used:
[0073]
[0074] in,
[0075] is the flow through the tank bleed valve,
[0076] is the volume of the gas in the tank,
[0077] is the specific gas constant of the gas in the tank,
[0078] is the temperature of the gas in the tank,
[0079] is the pressure gradient in the tank.
[0080] Obviously, the pressure gradient and the volume and temperature of the gas in the fuel tank 6 are incorporated into the flow rate (i.e. the mass flow rate from the fuel tank 6). By integration, the throughflow rate, i.e. the mass that escapes from the fuel tank 6 during the time period of the venting process, can be determined from the flow rate, in particular according to the following relationship:
[0081]
[0082] in,
[0083] is the flow through the tank bleed valve, and
[0084] is from t0 to t ende The flow rate that has flowed through the tank vent valve during the time period.
[0085] In parallel, the flow through the tank ventilation valve 5 can be determined according to the model described. Accordingly, the modeled flow rate can also be determined from the modeled flow rate by integration.
[0086] To illustrate the story Figure 2 . Figure 2 Three graphs arranged one above the other are shown, wherein the upper graph shows two states (i.e., open and closed) of the shut-off valve 7 with respect to the time axis, the middle graph shows the relative pressure at the sensor 4 with respect to the corresponding time scale, and the lower graph shows the mass flow through the tank vent valve 5 with respect to the corresponding time scale.
[0087] Obviously, the shut-off valve 7 is closed in the time period from about 30 seconds to 90 seconds and from 130 seconds onwards, which represents the venting of the fuel tank 6. During this time period, the relative pressure measured at the sensor 4 decreases accordingly. Figure 2 The bottom chart shows not only the modeled flow , and shows the flow through the tank vent valve 5 detected at the pressure sensor 8 during venting This amount is determined according to the relationship set out above, wherein, according to the present invention, the flow rate It is determined only during the closing phase of the shut-off valve 7 , ie only during exhaustion.
[0088] The balance of the flow rate acquired during the exhaust and the modeled flow rate or the corresponding flow rate represents the following steps. The result of this balance (for example by establishing the modeled flow rate To the flow rate obtained during exhaust The relative deviation can be characterized by the adaptation factor C AD The adaptation factor C AD The following relationship can be used in the calculation of the flow through the tank vent valve 5:
[0089]
[0090] Therefore, in this sense, the model on which the modeled traffic is based can be adjusted.
Claims
1. A method for obtaining the flow rate of gas passing through a timing valve (5), comprising the following steps: - acquiring the pressure at a pressure sensor upstream of the timing valve (5) during venting of a container (6) arranged upstream of the timing valve (5), wherein, The container (6) is a fuel tank, - obtaining the flow rate through the timing valve (5) based on the pressure obtained upstream of the timing valve (5) and based on the temperature of the gas in the container (6) obtained by a temperature sensor and the volume of the gas in the container (6), - compare the flow rate acquired during exhaust with the modeled flow rate, - adjusting the model when a deviation occurs between the flow rate acquired during exhaust and the modeled flow rate, The flow rate through the timing valve (5) in a preset time period is determined by the flow rate obtained during the exhaust period, and is determined according to the following relationship: in, is the flow through the timing valve (5) during exhaust, and m ausTank is from t0 to t ende The flow rate that has flowed through the timing valve (5) during the time period.
2. The method according to claim 1, characterized in that: The flow rate through the timing valve (5) during exhaust is obtained according to the following relationship: in, is the flow rate through the timing valve (5) during exhaust, V GasTank is the volume of the gas in the container (6), R GasTank is the specific gas constant of the gas in the container (6), T GasTank is the temperature of the gas in the container (6), is the pressure gradient in the container (6).
3. The method according to claim 1 or 2, characterized in that: One or more of the following parameters are set in the model on which the modeled flow is based: the pressure detected upstream of the timing valve (5), the pressure detected downstream of the timing valve (5), the cross-sectional area of the flow through the timing valve (5), the obtained opening time point of the timing valve (5), and the obtained closing time point of the timing valve (5).
4. The method according to claim 3, characterized in that The modeling of the flow through the timing valve (5) is achieved in the following way: the flow through the timing valve (5) is determined taking into account the pressure detected upstream of the timing valve (5), the pressure detected downstream of the timing valve (5), the acquired opening time point of the timing valve (5) and the acquired closing time point of the timing valve (5).
5. The method according to claim 4, characterized in that The following relationship is used to model the flow through the timing valve (5): in, is the flow rate through the timing valve (5), A r is the reduced flow cross-sectional area of the timing valve (5), Ψ is the flow parameter, P nach,TEV is the pressure detected downstream of the timing valve (5), P vor，TEV is the pressure detected upstream of the timing valve (5), k is the isentropic exponent of the mass flow through the timing valve (5), and R s is the specific gas constant for the mass flow rate through the timing valve (5).
6. The method according to claim 5, characterized in that The flow parameters are obtained according to the following relationship: Among them, pc r is the critical pressure ratio.
7. The method according to claim 1 or 2, characterized in that Modelling of the flow through the timing valve (5) and / or modelling of quantities related to the flow.
8. The method according to claim 1 or 2, characterized in that: The container (6) is vented by a scavenging pump (2) arranged between the container (6) and the timing valve (5) or by negative pressure in an intake pipe section (10) arranged downstream of the timing valve (5).
9. The method according to claim 1 or 2, characterized in that: The pressure during exhaustion upstream of the timing valve (5) is detected by means of a pressure sensor (3) which is arranged in the container (6) or in a line extending between the container and the timing valve (5).
10. The method according to claim 1 or 2, characterized in that: The timing valve (5) is a material box air release valve.
11. A device for detecting the flow of a gas through a timing valve (5), comprising a control unit (12) configured to implement the method according to any one of the preceding claims.