Cleaning apparatus and method for a gas stream charged with hydrocarbon vapors

Abstract

A fuel vapor removal device (10) for storing fuel vapor in the fuel tank (30) of a thermally powered motor vehicle (1) includes a control module (130), which is specifically configured to: determine the contribution of airflow convection to the temperature of the airflow based on received airflow temperature measurements and received pump internal temperature measurements; determine the contribution of airflow conduction to the airflow temperature based on airflow mass flow rate, received airflow temperature and received pump internal temperature measurements; estimate the temperature of the airflow flowing in the removal loop (120) based on the determined contributions of adiabatic compression, convection and conduction; and calculate the fuel vapor concentration of the airflow based on the estimated temperature.

Description

Technical Field

[0001] This invention relates to the treatment of hydrocarbon vapors in motor vehicles, and more specifically to a purge device for hydrocarbon vapors in the thermal engines of motor vehicles. The invention is particularly applicable to hybrid vehicles and vehicles powered solely by thermal engines. Throughout the text, the term "fuel" advantageously refers to at least one hydrocarbon. Background Technology

[0002] In motor vehicles equipped with heat engines, the fuel stored in the fuel tank needs to be in contact with outside air. This allows for the release of fuel vapors and the introduction of air into the fuel tank as fuel levels decrease. This necessitates regulating the pressure of the gases contained in the fuel tank to prevent excessive pressure fluctuations, which could lead to material and personal hazards. One known solution is to create a vent in the fuel tank's seal to allow these hydrocarbon vapors to be released directly to the outside of the vehicle while simultaneously allowing air into the fuel tank to balance the pressure. The main drawback of releasing these hydrocarbon vapors into the atmosphere is severe environmental pollution. However, given the increasingly stringent regulations in this area, some of which require strict limits on hydrocarbon vapor emissions into the atmosphere, such emissions are becoming increasingly undesirable and impractical.

[0003] Furthermore, to limit pollution, it is known to install a filter device in the vehicle's fuel intake system. Such a device is connected to the fuel tank on one side and to the outside of the vehicle on the other. In known solutions, this device includes a decarbonization filter, hereinafter referred to as an "absorption filter" (often called a "canister" by those skilled in the art), which allows the absorption of hydrocarbon vapors from the fuel tank, ensuring that fuel emissions emitted into the atmosphere by the emission devices are in gaseous form, and that the gaseous emissions are significantly purified of the pollutants contained in the hydrocarbon vapors.

[0004] However, such an absorption filter has a limited absorption capacity, namely the filter's maximum load. This is referred to as the absorption filter being "full" or "filled," or saturated. In this state, the filter can no longer retain hydrocarbon vapors, allowing them to escape into the atmosphere. More generally, regardless of whether the absorption filter is saturated, it has a specific load characteristic at a given moment, the load corresponding to the mass percentage of fuel stored in the filter relative to its saturation value (i.e., relative to its maximum load).

[0005] To limit the harmful release of fuel into the atmosphere when the filter is saturated, it needs to be cleaned periodically, ideally before it becomes saturated with hydrocarbon vapors. For this purpose, the device is connected to the vehicle's engine so that the hydrocarbon vapors absorbed by the filter can be directly injected into the combustion chamber of the engine cylinders during engine operation, causing them to burn. In other words, the absorption filter is periodically filled with hydrocarbon vapors from the fuel tank, and then the engine control computer intermittently unloads the load from the absorption filter into the combustion chamber of the engine cylinders during engine operation.

[0006] The delivery of hydrocarbon vapors from the filter to the heat engine occurs via a purging valve in the purging circuit, which allows the purging circuit to be placed under vacuum. However, with the advent of hybrid vehicle technology, purging hydrocarbon vapors from the filter has become increasingly difficult because placing the purging circuit under vacuum is more challenging in hybrid vehicles. Indeed, in hybrid vehicles, the heat engine is preferably used when high engine speeds are required. However, at high speeds, the intake throttle is open, which reduces the low pressure in the purging circuit. Furthermore, due to this operating mode, the available time for the heat engine to perform purging is decreasing, potentially leading to hydrocarbon vapor emissions into the atmosphere because the filter is more frequently saturated when purging is not possible.

[0007] Known solutions to this problem involve using a radial pump, called an active cleaning pump, between the filter and the engine to allow hydrocarbon vapors to flow into the engine through the cleaning circuit. In this way, a corresponding volume of air is needed to compensate for the amount of hydrocarbon vapors introduced into the engine cylinders in order to maintain the stoichiometric air-fuel ratio required for good combustion of the mixture in a thermal engine.

[0008] In existing solutions, it is known to estimate the concentration of hydrocarbon vapor in the airflow flowing between the filter and the engine, and to control the introduction of the airflow into the engine cylinders according to the concentration in a proportion corresponding to the stoichiometric ratio.

[0009] Of course, any error in airflow control implies a relative deviation from the stoichiometric ratio, which leads to variations in the hydrocarbon vapor concentration of the absorber, thus affecting the real-time estimation of that concentration. Consequently, the estimated hydrocarbon vapor concentration can vary between 0% and 200%, while the actual concentration cannot exceed 80%. Therefore, airflow control can err, and any control error will result in a deviation. However, the system remains relatively stable because control is achieved through an oxygen probe (called an oxygen sensor) located in the engine exhaust circuit. The control is performed in a closed loop (using a probe). However, such control is obviously slow compared to the rapid injection frequency. Therefore, it is crucial to be able to accurately estimate the concentration of hydrocarbon vapors.

[0010] The concentration of hydrocarbon vapors can be estimated based on the pressure difference between the input and output of the active cleaning pump. This pressure difference depends on the pump's rotational speed and the density of the gas flowing within the pump. Since the pump's rotational speed is determined by the cleaning flow rate required to be absorbed by the engine, it can change very rapidly, for example, from 10,000 rpm to 60,000 rpm in 1 second, and from 60,000 rpm to 10,000 rpm in 2 seconds. This speed change means a change in the operating point, which in turn alters the pressure and temperature, and consequently the gas density due to the adiabatic compression of the radial pump. However, this density also depends on the ambient pressure (i.e., the atmospheric pressure entering the absorber filter), the gas flow temperature, and the concentration of hydrocarbon vapors. Therefore, accurate knowledge of the ambient pressure and gas flow temperature is required to determine the hydrocarbon vapor concentration based on the pressure difference and thus on the density, in order to correct injection parameters as quickly and accurately as possible, for example, by applying such injection correction every 20 ms.

[0011] Ambient pressure is measured using a pressure sensor mounted on the cleaning circuit, or by another sensor connected to the engine control unit, such as near the active cleaning pump. In existing solutions, temperature is measured using a sensor positioned before or after the active cleaning pump and a passive temperature sensor of the CTN (Coefficient de Température Négatif, negative temperature coefficient) type. However, with this technique, the response time for temperature measurement depends on the airflow velocity, varying, for example, between 0 and 80 l / min, and can therefore be particularly long. For example, the response time can be approximately 25 seconds when the flow rate is zero, and approximately 5 seconds when the flow rate is 80 l / min. Other thermocouple-type temperature sensors can also be used. However, the response time of these sensors depends on their inherent technology, and the cost increases inversely with their response time. Furthermore, fast-response thermocouple sensors are used in laboratories and are too expensive for mass-produced motor vehicles. In either case, the response time of low-cost temperature sensors used in the automotive industry is too long to accurately estimate hydrocarbon vapor concentrations in real time, and also to simultaneously control airflow into the engine cylinders accurately and quickly. Therefore, it is advantageous to propose solutions that can at least partially overcome these shortcomings. Summary of the Invention

[0012] One objective of this invention is to accurately and quickly estimate the temperature of the gas flow in the cleaning circuit. Another objective is to accurately measure the fuel vapor concentration of the gas flow in the cleaning circuit. A further objective is to accurately control the flow rate of the cleaning gas entering the engine cylinders.

[0013] Therefore, the subject of this invention is primarily a device for cleaning fuel vapor stored in the fuel tank of a hybrid or thermal power vehicle, the vehicle including a thermal engine and a fuel tank for storing fuel intended to be burned in the engine, the device comprising:

[0014] - An absorption filter that filters out vapors in the form of hydrocarbons produced by the fuel stored in the fuel tank.

[0015] - The so-called "cleaning circuit," which is connected to the absorber filter and is intended to be connected to the engine, includes:

[0016] A pump, preferably a radial (or centrifugal) pump, directs the flow of hydrocarbon-containing vapors from the absorption filter toward the engine.

[0017] The pressure sensor located upstream of the pump is called the "upstream pressure sensor".

[0018] A pressure sensor located downstream of the pump is called a "downstream pressure sensor".

[0019] At least one temperature sensor, configured to measure the temperature of the airflow, is preferably located at least upstream of the pump.

[0020] A purge valve is configured to switch between an open position and a closed position. In the open position, the purge valve allows airflow from the absorber filter to the engine; in the closed position, the absorber filter is isolated from the engine.

[0021] - The control module, configured in cleanup mode as follows:

[0022] It receives measurement values ​​from upstream and downstream pressure sensors.

[0023] The pressure difference between the pump's input and output airflow is calculated based on the received upstream and downstream pressure measurements.

[0024] It receives temperature measurements from a temperature sensor, the pump's rotational speed, and the pump's internal temperature.

[0025] The mass flow rate of the airflow is determined based on the received pump rotation speed.

[0026] The contribution of adiabatic compression of the airflow to its temperature is determined based on the calculated pressure difference and the received airflow temperature measurements.

[0027] The contribution of airflow convection to the airflow temperature is determined based on the received airflow temperature measurement and the received pump internal temperature measurement.

[0028] The contribution of airflow conduction to airflow temperature is determined based on the measured values ​​of the determined airflow mass flow rate, the received airflow temperature, and the received pump internal temperature.

[0029] The temperature of the gas flow in the cleaning loop is estimated based on the determined contributions of adiabatic compression, convection, and conduction.

[0030] The fuel vapor concentration in the airflow is calculated based on the estimated temperature, received pressure measurements, and received pump rotation speed.

[0031] The purge valve is operated to control the airflow into the cylinder based on a calculated concentration, while adhering to the stoichiometric ratio of the air-fuel mixture in the engine cylinder.

[0032] The use of contributions from adiabatic compression, convection, and conduction advantageously enables reliable, rapid, and accurate control of airflow in the engine cylinders to follow the engine's stoichiometry without relying on sensor delays.

[0033] According to the present invention, the contribution T of the adiabatic compression of the airflow to the temperature of the airflow is determined according to the following formula. Flow_Adb :

[0034]

[0035] in, T Inlet The airflow temperature is received from the flow temperature sensor upstream of the pump. P Flow It is the airflow pressure received from the downstream pressure sensor. P Inlet The airflow pressure is measured by an upstream pressure sensor, and γ is an ideal gas constant, which is assumed to be constant within the considered temperature and pressure range.

[0036] The contribution of airflow convection to the airflow temperature is determined based on the following formula, using measurements of the received airflow temperature and the received pump internal temperature:

[0037]

[0038] in, HeatFac Conv This refers to the heat exchange between the pump material and the airflow through convection and radiation. T BodyIt is the temperature of the pump body, corresponding to the internal temperature of the pump, and T Inlet The airflow temperature is measured by a flow temperature sensor.

[0039] Furthermore, the contribution of airflow conduction (or absorption) to airflow temperature is determined based on the following formula, using measurements of the determined airflow mass flow rate, the received airflow temperature, and the received pump internal temperature:

[0040]

[0041] in, It is the mass flow rate of the airflow through the pump (unit: kg / h). HeatFac Cond It is the heat exchange between the pump material and the airflow through conduction. T Body It is the internal temperature of the pump, and T Inlet The airflow temperature is measured by a flow temperature sensor.

[0042] Furthermore, the control module then calculates an estimate of the temperature of the airflow in the cleaning loop based on the determined contributions of adiabatic compression, convection, and conduction, according to the following formula:

[0043] .

[0044] According to one aspect of the invention, the control module is configured to calculate the fuel vapor concentration of the airflow based on the estimated temperature using the following formula:

[0045]

[0046] Where, ρ gas It is the density of the gas inside the pump, ρ air It is the density of air under the pressure and temperature inside the pump, and ρ but It is the density of butane under the pressure and temperature inside the pump.

[0047] Advantageously, the radial pump is an electric pump.

[0048] Advantageously, temperature sensors are placed at the pump's input and / or output.

[0049] Preferably, the control module is configured to determine the end of hydrocarbon vapor purging, close the purging valve, and operate the pump at a predetermined minimum speed in a so-called "non-purging mode." In fact, without a purging phase (i.e., no purging flow), if the turbine continues to rotate at very high speeds, such as 60,000 tr / min, the airflow on the pump blades becomes unstable, generating considerable forces on the rotating shaft and turbine. Prolonged operation in this mode can lead to premature pump wear. Therefore, it is necessary to reduce the pump's rotational speed to eliminate instability. If the temperature sensor is located far from the pump output, for example, more than 10 cm, heat will not propagate or will have difficulty propagating to the sensor due to the lack of flow, resulting in an excessively long sensor response time, such as exceeding 30 seconds. In this case, the temperature in the pump cannot be calculated based on the temperature information provided by a sensor located downstream of the pump. A model should be used instead of the sensor value. In this case, the temperature at the pump output will be equivalent to the temperature generated by adiabatic compression. If the temperature sensor is placed near the pump's output, for example, at a distance of less than 10 cm, the heat generated by the pump is transferred to the sensor, and the sensor's temperature value can be used to replace the model's value. Furthermore, since there is no flow, the heat generated by the pump returns to the pump's input. Therefore, the temperature throughout the pump is almost uniform, and the input temperature is thus equal to the temperature contributed by the adiabatic flow.

[0050] The present invention also relates to a motor vehicle comprising the aforementioned apparatus, a thermal engine including at least one cylinder, and a fuel tank for storing fuel intended to be burned in the at least one cylinder of the engine.

[0051] The present invention also relates to a method for controlling the flow rate of an airflow in a cleaning device as described above, the method being implemented by a control module of the cleaning device and comprising the following steps:

[0052] - Receive at least one measurement of the airflow pressure upstream of the pump.

[0053] - Receive at least one measurement of the airflow pressure downstream of the pump.

[0054] - Calculate the pressure difference of the airflow between the pump's input and output.

[0055] - Receive at least one temperature measurement value from the flow temperature sensor.

[0056] - Receive at least one measurement of the pump's rotational speed and the pump's internal temperature.

[0057] - Determine the mass flow rate of the airflow based on the received pump rotation speed.

[0058] - The contribution of adiabatic compression of the airflow to its temperature is determined based on the calculated pressure difference and the received airflow temperature measurements.

[0059] - The contribution of airflow convection to the airflow temperature is determined based on the received airflow temperature measurement and the received pump internal temperature measurement.

[0060] - The contribution of airflow conduction to airflow temperature is determined based on the determined mass flow rate of the airflow, the received airflow temperature, and the received internal temperature measurement of the pump.

[0061] - Estimate the temperature of the gas flow in the cleaning loop based on the determined contributions of adiabatic compression, convection, and conduction.

[0062] - Calculate the fuel vapor concentration in the airflow based on the estimated temperature.

[0063] - Operate the purge valve to control the airflow into the cylinder based on a calculated concentration, while adhering to the stoichiometric ratio of the air-fuel mixture in the engine cylinder.

[0064] According to the present invention, the contribution T of the adiabatic compression of the airflow to the temperature of the airflow is determined according to the following formula. Flow_Adb :

[0065]

[0066] in, T Inlet It is the airflow temperature received from the flow temperature sensor. P Flow It is the airflow pressure received from the downstream pressure sensor. P Inlet The airflow pressure is measured by an upstream pressure sensor, and γ is an ideal gas constant, which is assumed to be constant within the considered temperature and pressure range.

[0067] The contribution of airflow convection to the airflow temperature is determined based on the following formula, using measurements of the received airflow temperature and the received pump internal temperature:

[0068]

[0069] in, HeatFac Conv This refers to the heat exchange between the pump material and the airflow through convection and radiation. T Body It is the internal temperature of the pump, and T Inlet The airflow temperature is measured by a flow temperature sensor.

[0070] Furthermore, the contribution of airflow conduction to airflow temperature is determined based on the following formula, using measurements of the determined airflow mass flow rate, the received airflow temperature, and the received pump internal temperature:

[0071]

[0072] in, It is the mass flow rate of the airflow through the pump. HeatFac Cond It is the heat exchange between the pump material and the airflow through conduction. T Body It is the internal temperature of the pump, and T Inlet The airflow temperature is measured by a flow temperature sensor.

[0073] Furthermore, the control module then calculates an estimate of the temperature of the airflow in the cleaning loop based on the determined contributions of adiabatic compression, convection, and conduction, according to the following formula:

[0074] .

[0075] Advantageously, the fuel vapor concentration of the airflow can be calculated based on the estimated temperature using the following formula:

[0076]

[0077] Where, ρ gas It is the density of the gas inside the pump, ρ air It is the density of air under the pressure and temperature inside the pump, and ρ but It is the density of butane under the pressure and temperature inside the pump.

[0078] According to one aspect of the invention, the method further includes the steps of: determining the moment when the cleaning of hydrocarbon vapors ends, closing the cleaning valve, and manipulating the pump to operate at a predetermined minimum speed in a so-called "non-cleaning mode".

[0079] The present invention also relates to a computer program product, characterized in that it includes a set of program code instructions, which, when executed by one or more processors, configure the one or more processors to implement the method described above. Attached Figure Description

[0080] Other features and advantages of the invention will become more apparent from the following description. This description is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0081] Figure 1 An embodiment of a vehicle according to the present invention is illustrated schematically.

[0082] Figure 2 An embodiment of the method according to the present invention is illustrated schematically. Detailed Implementation

[0083] The device according to the invention is intended to be installed in a vehicle and enables the vaporization of fuel vapor stored in the fuel tank of a hybrid or thermal motor vehicle, and the removal of hydrocarbon vapors generated by said fuel by combustion in the engine.

[0084] Figure 1 A vehicle 1 is shown. Vehicle 1 includes a device 10 according to the invention, a thermal engine 20, and a fuel tank 30 for storing fuel to be burned in said engine 20. Engines are known to include cylinders (not shown) that enable the mixing of fuel and air to allow them to burn.

[0085] The device 10 includes an absorption filter 110, a so-called "cleaning loop" 120, and a control module 130.

[0086] The absorption filter 110 enables the filtering of vapors in the form of hydrocarbons produced by the fuel stored in the fuel tank 30. For this purpose, the absorption filter 110 is connected to the fuel tank 30 via a conduit 31.

[0087] The absorber filter 110 is connected to the outside of the vehicle (atmosphere) via a conduit 111, in which an air valve 112 is installed. The air valve 112 is configured to switch between an open and a closed position. In the open position, the air valve 112 allows gas filtered by the absorber filter 110 to be discharged to the outside; in the closed position, the device 10 is isolated from the outside of the vehicle 1. The air valve 112 is optional and can be used to detect leaks.

[0088] The absorption filter 110 is also connected to the cylinder of the engine 20 via the cleaning circuit 120.

[0089] The cleaning circuit 120 connects the absorption filter 110 to the cylinder of the engine 20 of the vehicle 1 and includes a radial (or centrifugal) pump 121, a so-called "upstream pressure sensor" 122, a so-called "downstream pressure sensor" 123, a flow temperature sensor 124, and a cleaning valve 125.

[0090] The radial pump 121 (preferably an electric pump) enables the gas stream containing hydrocarbon vapors to flow from the absorber filter 110 to the engine 20 in the cleaning circuit 120. The pump 121 can also measure its rotational speed and internal temperature, especially to prevent its motor and electronics from overheating, and can send these measurements to the control module.

[0091] An upstream pressure sensor 122 is installed upstream of pump 121 and can measure the pressure of the airflow flowing between absorber filter 110 and pump 121.

[0092] A downstream pressure sensor 123 is installed downstream of pump 121 and measures the pressure of the airflow flowing between pump 121 and purge valve 125. Preferably, the downstream pressure sensor 123 uses a pressure model based on the air intake into the engine after filtering to determine and provide the temperature of the airflow at the downstream pressure sensor 123.

[0093] In this example, the flow temperature sensor 124 is mounted upstream of the pump 121 and configured to measure the temperature of the airflow flowing between the absorption filter 110 and the pump 121. In another embodiment, the flow temperature sensor 124 may be mounted downstream of the pump 121. In yet another embodiment, the device 10 may include two temperature sensors, one downstream and one upstream of the pump 121, to improve the accuracy of the temperature module.

[0094] The purge valve 125 is configured to switch between an open position and a closed position. In the open position, the purge valve 125 allows airflow from the absorber filter 110 to the engine 20; in the closed position, the absorber filter 110 is isolated from the engine 20. The opening or closing of the purge valve 125 can be controlled by the control module 130, specifically controlled to multiple open positions, so that airflow from the absorber filter 110 can be injected into the cylinder at various flow rates.

[0095] The control module 130 is configured to control the pump 121, and in particular the operating speed of the pump 121.

[0096] The control module 130 is configured to receive measured values ​​from the upstream pressure sensor 122 and the downstream pressure sensor 123.

[0097] The control module 130 is configured to calculate the pressure difference between the airflow at the input and output of the pump 121 based on upstream and downstream pressure measurements received from upstream pressure sensor 122 and downstream pressure sensor 123.

[0098] The control module 130 is configured to receive temperature measurements from the flow temperature sensor 124.

[0099] Control module 130 is configured to periodically, preferably frequently (i.e., continuously), determine the mass flow rate of the airflow through purge valve 125 and pump 121. Since the airflow through pump 121 is the same as the airflow through purge valve 125, the mass flow rate can be determined based on a predefined model that uses the airflow pressure measured by downstream pressure sensor 123, the airflow temperature at the input of purge valve 125, the airflow temperature at the output of purge valve 125, and the open position of purge valve 125 as inputs. For this purpose, temperature sensors (not shown) can be located on both sides of purge valve 125, or according to a separate model based on the electrical characteristics of purge valve 125, or according to temperature information that can also be provided by pressure sensor 123, or according to a model using a known downstream temperature model of pump 121. Preferably, the last three types of information are combined to improve accuracy depending on the usage pattern. Information about the open position of the cleaning valve 125 can be received from the cleaning valve 125 or determined by the control module 130, for example, by using a model based on the opening operation of the cleaning valve 125, taking into account the opening and closing time of the cleaning valve 125, such a model is known in itself.

[0100] The control module 130 is configured to receive, for example, a measurement of the internal temperature of the pump 121 of the vehicle 1 via a CAN-type data communication bus.

[0101] The control module 130 is configured to determine the contribution of adiabatic compression of the airflow to the temperature of the airflow based on the calculated pressure difference and the received temperature measurement of the airflow.

[0102] The control module 130 is configured to determine the contribution of airflow convection to the temperature of the airflow based on the received temperature measurement of the airflow and the internal temperature measurement of the pump 121.

[0103] The control module 130 is configured to determine the contribution of airflow conduction to the airflow temperature based on the determined mass flow rate of the airflow, the temperature of the received airflow, and the internal temperature measurement of the pump 121.

[0104] The control module 130 is configured to estimate the temperature of the airflow flowing in the cleaning loop 120 based on the determined contributions of adiabatic compression, convection and conduction.

[0105] The control module 130 is configured to calculate the fuel vapor concentration of the stream based on the estimated temperature.

[0106] In the so-called "cleaning mode", the control module 130 is configured to operate the cleaning valve 125 to control the flow rate of the stream entering the cylinder based on a calculated concentration, while adhering to the stoichiometric ratio of the air-fuel mixture with respect to the cylinders of the engine 20.

[0107] The control module 130 includes a processor capable of executing a set of instructions that enable these functions to be implemented.

[0108] Implementation

[0109] As a prerequisite, the device is assumed to be operating in non-cleaning mode initially. When the control module determines that cleaning of the absorption filter (cleaning mode) needs to be performed, the control module 130 manipulates the pump 121 to operate at a predetermined speed (e.g., minimum speed) and opens the cleaning valve 125.

[0110] As the gas stream filled with hydrocarbon vapor flows from the absorber filter 110 toward the engine 20 through the cleaning circuit 120, the upstream pressure sensor 122 and the downstream pressure sensor 123 periodically measure the gas stream pressure and send their measurements to the control module 130 (steps E1 and E2, respectively). The control module 130 then calculates the pressure difference between the input and output of the pump 121 based on the current pressure values ​​received from the upstream pressure sensor 122 and the downstream pressure sensor 123 (step E3).

[0111] In parallel, the flow temperature sensor 124 also periodically measures the temperature of the airflow and sends its measurement to the control module 130 (step E4).

[0112] In parallel, in step E5, the control module 130 also receives the rotational speed of pump 121 and the internal temperature of pump 121 directly transmitted by pump 121 (e.g., via the data communication bus of vehicle 1).

[0113] Then, control module 130 determines the mass flow rate of the airflow based on the rotational speed of pump 121 and the pressure and temperature values ​​across purge valve 125 (step E6). The pump rotational speed allows characterization of the airflow cross-section in purge valve 125, which is used to calculate the mass flow rate in a manner known per se. The pressure and temperature values ​​across purge valve 125 can be established based on a predefined model stored in the storage area of ​​control module 130, which is in tabular form and includes ambient atmospheric pressure and airflow entering the engine as inputs.

[0114] Then, control module 130:

[0115] The contribution of adiabatic compression of the airflow to the airflow temperature is determined based on the calculated pressure difference and the temperature measurement of the received airflow (step E7).

[0116] The contribution of airflow convection to the airflow temperature is determined based on the received airflow temperature measurement and the received internal temperature measurement of pump 121 (step E8).

[0117] The contribution of flow conduction to the temperature of the airflow is determined based on the mass flow rate of the airflow, the received airflow temperature, and the received internal temperature measurement of the pump (step E9).

[0118] Theoretically, the calculation requires the temperature value of the pump body 121, not the internal temperature of the pump 121. The pump 121 includes an internal sensor that allows measurement of the internal temperature, but not the temperature of the pump body. However, although the internal temperature of the pump 121 and the temperature of the pump body are not exactly the same, their kinetics are similar. Therefore, the internal temperature of the pump 121 is a good image of the temperature of the pump body.

[0119] The contribution T of the adiabatic compression of the airflow to the temperature of the airflow is determined according to the following formula. Flow_Adb :

[0120]

[0121] in, T Inlet It is the airflow temperature received from the flow temperature sensor. P Flow It is the airflow pressure received from the downstream pressure sensor 123 and P Inlet The airflow pressure is measured by the upstream pressure sensor 122, and γ is an ideal gas constant, with a value between 1.2 and 1.4 depending on the gas being considered.

[0122] The contribution of airflow convection to the airflow temperature is determined based on the following formula, using measurements of the received airflow temperature and the received internal temperature of pump 121:

[0123]

[0124] in, HeatFac Conv This refers to the heat exchange between the pump material and the airflow through convection and radiation. T Body It is the internal temperature of pump 121, and T Inlet The airflow temperature is measured by the airflow temperature sensor 124.

[0125] Furthermore, the contribution of airflow conduction to airflow temperature is determined based on the following formula, using measurements of the airflow mass flow rate, the received airflow temperature, and the received pump internal temperature:

[0126]

[0127] in, It is the mass flow rate of the airflow through the pump. HeatFac Cond This indicates the heat exchange between the material of pump 121 and the airflow via conduction. T Body It is the internal temperature of pump 121, and T Inlet The airflow temperature is measured by the airflow temperature sensor 124.

[0128] Control module 130 then calculates the estimated temperature of the airflow in the cleaning loop 120 in step E10 based on the determined contributions of adiabatic compression, convection, and conduction according to the following formula:

[0129] .

[0130] Once the temperature is estimated, the control module 130 calculates the fuel vapor concentration of the airflow based on the estimated temperature in step E11 according to the following formula:

[0131]

[0132] Where, ρ gas It is the density of the gas inside pump 121, ρ air It is the density of air under the pressure and temperature inside pump 121, and ρ but It is the density of butane under the pressure and temperature inside pump 121.

[0133] Then, in step E12, the control module 130 manipulates the cleaning valve 125 to control the airflow into the cylinder based on the calculated concentration, while adhering to the stoichiometric ratio of the air-fuel mixture in the cylinder of the engine 20.

[0134] The control can be performed, for example, based on a table stored in a storage area accessible to the control module 130, which stores a correspondence between the hydrocarbon vapor concentration of the airflow and the opening of the purge valve 125, such correspondences enabling adherence to the stoichiometry of the engine 20.

[0135] When the control module 130 determines that the cleaning mode has ended (step E13), the control module 130 closes the cleaning valve 125 (step E14) and operates the pump 121 (step E15), for example by controlling the pump 121 to its minimum speed, to prevent premature wear of one or more materials constituting the pump 121.

[0136] Therefore, the present invention advantageously enables simple, reliable and accurate control of the airflow in the cylinder of engine 20 to follow the stoichiometry of engine 20.

Claims

1. A device (10) for cleaning fuel vapor stored in the fuel tank of a hybrid or thermal power vehicle (1), the vehicle (1) including a thermal engine (20) and a fuel tank (30) for storing fuel intended to be burned in the engine (20), the device comprising: - An absorption filter (110) that filters out vapors in the form of hydrocarbons produced by the fuel stored in the fuel tank (30). - A cleaning circuit (120), which is connected to the absorption filter and is intended to be connected to the engine (20), and includes: Pump (121) directs the flow of hydrocarbon vapor from the absorber filter (110) toward the engine (20). The pressure sensor located upstream of the pump (121) is called the "upstream pressure sensor (122)". The pressure sensor located downstream of the pump (121) is called the "downstream pressure sensor (123)". A flow temperature sensor (124) is configured to measure the temperature of the airflow. A cleaning valve (125) is configured to switch between an open position and a closed position. In the open position, the cleaning valve allows airflow from the absorber filter (110) to the engine (20). In the closed position, the absorber filter (110) is isolated from the engine (20). - Control module (130), which is configured in cleanup mode as follows: It receives measurement values ​​from the upstream pressure sensor (122) and the downstream pressure sensor (123). The pressure difference between the input and output of the pump (121) is calculated based on the received upstream and downstream pressure measurements. It receives temperature measurements from the flow temperature sensor (124), the rotational speed of the pump (121), and the internal temperature of the pump (121). The mass flow rate of the airflow is determined based on the received rotational speed of the pump (121). The contribution T of the adiabatic compression of the airflow to the temperature of the airflow is determined based on the calculated pressure difference and the received airflow temperature measurement using the following formula. Flow_Adb : in, T Inlet It is the airflow temperature received from the flow temperature sensor. P Flow It is the airflow pressure received from the downstream pressure sensor (123). P Inlet The airflow pressure is measured by the upstream pressure sensor (122), and γ is the ideal gas constant. The contribution of airflow convection to the temperature of the airflow is determined according to the following formula, based on the received temperature measurement of the airflow and the received internal temperature measurement of the pump (121): in, HeatFac Conv It is a quantity used to represent the heat exchange between the material of the pump (121) and the airflow through convection and radiation. T Body It is the internal temperature of the pump (121), and T Inlet The airflow temperature is measured by the flow temperature sensor (124). The contribution of airflow conduction to airflow temperature is determined based on the following formula, using measurements of the determined mass flow rate of the airflow, the temperature of the received airflow, and the internal temperature of the received pump (121): in, It is the mass flow rate of the airflow through the pump (121). HeatFac Cond It is a quantity used to represent the heat exchange between the material of the pump (121) and the airflow via conduction. T Body It is the internal temperature of the pump (121), and T Inlet The airflow temperature is measured by the flow temperature sensor (124). The temperature of the gas flow in the cleaning loop is estimated based on the determined contributions of adiabatic compression, convection, and conduction, according to the following formula: The fuel vapor concentration in the airflow is calculated based on the estimated temperature, received pressure measurements, and received pump rotation speed. The purge valve (125) is operated to control the airflow into the cylinder based on the calculated concentration, while adhering to the stoichiometric ratio of the air-fuel mixture in the cylinder of the engine (20).

2. The apparatus (10) according to claim 1, wherein, The control module (130) is configured to determine the moment when the cleaning of fuel vapor ends, close the cleaning valve (125), and manipulate the pump (121) so that the pump (121) operates in non-cleaning mode at a predetermined minimum speed.

3. The apparatus (10) according to claim 1 or 2, wherein, The control module (130) is configured to calculate the fuel vapor concentration of the airflow based on the estimated temperature using the following formula: Where, ρ gas It is the density of the gas inside the pump (121), ρ air It is the density of air under the pressure and temperature inside the pump (121), and ρ but It is the density of butane under pressure and temperature inside the pump (121).

4. A motor vehicle comprising a device (10) according to any one of claims 1 to 3, a thermal engine (20) comprising at least one cylinder, and a fuel tank (30) for storing fuel intended to be burned in the at least one cylinder of the engine (20).

5. A method for controlling the flow rate of an airflow flowing in a cleaning device (10) according to any one of claims 1 to 3, the method being implemented by a control module (130) of the device, and comprising the following steps: - Receive at least one measurement of the gas flow pressure upstream of the (E1) pump (121), - Receive at least one measurement of the gas flow pressure downstream of pump (121) (E2), - Calculate the pressure difference of the airflow between the input and output of pump (121) (E3). - Receive at least one temperature measurement value from the flow temperature sensor (124) (E4), - Receive at least one measurement of the rotational speed of the (E5) pump (121) and the internal temperature of the pump (121), - The mass flow rate of the (E6) airflow is determined based on the received rotational speed of the pump (121). - The contribution of the adiabatic compression of the gas flow to the temperature of the gas flow (T) is determined based on the calculated pressure difference and the temperature measurement of the received gas flow, according to the following formula (E7). Flow_Adb : in, T Inlet It is the airflow temperature received from the flow temperature sensor. P Flow It is the airflow pressure received from the downstream pressure sensor. P Inlet The airflow pressure is measured by the upstream pressure sensor (122), and γ is the ideal gas constant. - The contribution of airflow convection to the temperature of the airflow is determined according to the following formula based on the received airflow temperature measurement and the received pump internal temperature measurement: (E8) in, HeatFac Conv It is a quantity used to represent the heat exchange between the material of the pump (121) and the airflow through convection and radiation. T Body It is the internal temperature of the pump (121), and T Inlet The airflow temperature is measured by the flow temperature sensor (124). - The contribution of airflow conduction to airflow temperature is determined based on the following formula, using measurements of the determined airflow mass flow rate, the received airflow temperature, and the received pump internal temperature: (E9) in, It is the mass flow rate of the airflow through the pump (121). HeatFac Cond It is a quantity used to represent the heat exchange between the material of the pump (121) and the airflow via conduction. T Body It is the internal temperature of the pump (121), and T Inlet The airflow temperature is measured by the flow temperature sensor (124). - Estimate the temperature of the gas flow in the cleaning loop (E10) based on the determined contributions of adiabatic compression, convection, and conduction using the following formula: - Calculate the fuel vapor concentration of the (E11) airflow based on the estimated temperature. - Operate (E12) cleaning valve to control the airflow into the cylinder based on the calculated concentration, while adhering to the stoichiometric ratio of the air-fuel mixture in the cylinder of the engine (20).

6. The method according to claim 5, further comprising the steps performed by the control module: determining (E13) the time when the cleaning of fuel vapor ends, closing (E14) the cleaning valve (125), and manipulating (E15) the pump (121) so that the pump (121) operates in non-cleaning mode at a predetermined minimum speed.

7. The method according to claim 5 or 6, wherein, The fuel vapor concentration in the airflow is calculated based on the estimated temperature using the following formula: Where, ρ gas It is the density of the gas inside the pump (121), ρ air It is the density of air under the pressure and temperature inside the pump (121), and ρ but It is the density of butane under pressure and temperature inside the pump (121).

8. A computer program product, characterized in that, It includes a set of program code instructions that, when executed by one or more processors, configure the one or more processors to implement the method according to any one of claims 5 to 7.

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