Method and system for regulating combustion of an internal combustion engine
By installing an electric butterfly valve in the intake manifold of an internal combustion engine, the airflow is dynamically adjusted according to the engine speed and load, solving the problem of residual gas in the combustion chamber under low speed and light load. This achieves stable combustion and efficient operation of the engine under low speed and light load without increasing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- VTESCO TECH GMBH
- Filing Date
- 2021-11-17
- Publication Date
- 2026-06-12
AI Technical Summary
Under low speed and light load conditions, residual combusted gases in the combustion chamber slow down the combustion rate, which in turn makes the engine speed unstable. Existing solutions increase costs or impair high speed and high load performance.
By installing an electric butterfly valve in the intake manifold, the airflow in the intake manifold is dynamically adjusted according to the engine speed and load. The airflow is restricted or increased to control the air quality, ensuring that residual gases are effectively removed at low speeds and light loads. The adjustment method is implemented using a computer program product.
It achieves improved combustion stability at low speeds and light loads, increasing engine efficiency without affecting high-speed, high-load performance and avoiding additional costs.
Smart Images
Figure CN116472402B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to methods and systems for regulating combustion in internal combustion engines. More specifically, this disclosure relates to regulating an engine under light load and low speed.
[0002] This disclosure relates to the field of managing combustion in internal combustion engines. More specifically, this disclosure relates to single-cylinder engines, or more generally, to engines in which each cylinder includes a throttle valve. Such engines are typically forced-ignition engines. Background Technology
[0003] In the design of internal combustion engines, the pursuit of high performance often contradicts the goal of stable combustion at low speeds and light loads. In such engines, due to their structure, it is commonly observed that, at low speeds and light loads, burned gases remain in the combustion chamber at the end of the intake stroke. Therefore, without intervention, these residual gases slow down the combustion process, leading to unstable engine speeds.
[0004] Among the known solutions aimed at mitigating this problem, one involves injecting fresh air into the exhaust. Therefore, when the overall exhaust volume remains such that the λ sensor detects an overall abundance of 1, the air / fuel mixture can remain abundant in the combustion chamber. Consequently, the three-way catalytic converter in the corresponding engine can continue to operate effectively.
[0005] The first solution requires adding a device to the engine that allows fresh air to be injected into the exhaust, thus increasing the cost of engine manufacturing.
[0006] Another solution is to adjust the shape of the combustion chamber to promote turbulence within it, thereby better emptying the combustion chamber at the end of combustion.
[0007] This solution allows for improved engine stability at low speeds and light loads at a lower cost, but compromises performance at high speeds and heavy loads.
[0008] Therefore, the purpose of this disclosure is to provide a solution that enables the improvement of engine stability at low speeds and light loads at a lower cost without compromising engine performance at other operating points. Summary of the Invention
[0009] This disclosure will improve this situation.
[0010] First, a method for regulating combustion in an internal combustion engine is proposed. The engine is a single-cylinder engine or each cylinder includes a throttle valve. The engine includes an intake manifold with a regulating device that enables the airflow in the manifold to be regulated. The engine also includes a single cylinder associated with the regulating device. The engine is based on a four-stroke engine cycle.
[0011] According to this disclosure, the method includes the following steps:
[0012] - Determine the engine speed and / or load, and
[0013] - When the engine speed is below a predetermined value and / or the engine load is below a predetermined value, i.e. when the engine is running at a light load and / or low speed, the control of the regulating device that enables the airflow in the intake manifold to be adjusted such that: during the opening of the intake valve that enables the airflow to be introduced from the intake manifold into the corresponding cylinder, or at least during a portion of the opening time, the position of the throttle valve during the engine cycle is temporarily reduced compared to the other strokes of the engine cycle.
[0014] Therefore, air intake is restricted during the entire duration of the intake valve's opening, or at least during a portion of that opening. This creates a negative pressure upstream of the intake valve, which then promotes better air filling upstream of the intake valve by generating suction when the regulating device that controls airflow in the intake manifold returns to a position allowing more airflow.
[0015] In the proposed adjustment method, for example, the airflow in the intake manifold can be reduced during a time period corresponding to at least 180° CRK.
[0016] According to an embodiment of a regulating device that enables effective and rapid control of airflow in an intake manifold, the regulating device includes, for example, a butterfly valve, by pivoting the butterfly valve without closing it to achieve a reduction in airflow.
[0017] In one variation, the adjustment method according to this disclosure includes the following steps:
[0018] - Determine the engine speed and load.
[0019] - Determine the amount of fuel to be injected and the corresponding air mass.
[0020] - The average position control of the regulating device used to regulate airflow in the intake manifold enables the determination of the air quality during the engine cycle.
[0021] -During intake valve opening, the position of the regulating device is controlled to temporarily restrict airflow in the intake manifold compared to the average position, and
[0022] When the airflow is unrestricted, the position of the regulating device is controlled so that the airflow in the intake manifold during engine cycle can provide a defined air quality.
[0023] According to this embodiment of the adjustment method based on the present disclosure, when the intake valve is open, the airflow in the intake manifold can be restricted at least during the 180° CRK period corresponding to the passage from top dead center to the next passage of bottom dead center.
[0024] This disclosure also relates to:
[0025] - A computer program product comprising a series of code instructions, wherein when a computer implements the computer program product, the code instructions are used to implement the combustion regulation method of the aforementioned internal combustion engine;
[0026] - A computer adapted to regulate the combustion of an internal combustion engine, the engine including, on one hand, an intake manifold provided with a regulating device that enables regulation of airflow in the manifold, and on the other hand, a single cylinder associated with the regulating device, characterized in that the computer is also adapted to implement each step of the above-described regulation method.
[0027] - An internal combustion engine, on one hand including an intake manifold provided with a regulating device that enables the regulation of airflow in the manifold, and on the other hand including a single cylinder associated with the regulating device, characterized in that the engine further includes a computer as defined in the preceding paragraph: in such an engine, the regulating device that enables the regulation of airflow in the intake manifold advantageously includes an electric butterfly valve. Attached Figure Description
[0028] Other features, details, and advantages will become apparent by reading the following detailed description and studying the accompanying drawings, among which:
[0029] Figure 1 A cross-sectional view of a single-cylinder engine is shown schematically.
[0030] Figure 2 This schematically illustrates management using existing technology. Figure 1 The pressure change at the cylinder inlet of the engine.
[0031] Figure 3 This schematically illustrates management using existing technology. Figure 1 The control signal for the engine's butterfly valve.
[0032] Figure 4 It schematically shows the relationship with Figure 2 The changes are managed in accordance with this disclosure. Figure 1 The pressure change at the cylinder inlet of the engine.
[0033] Figure 5 The illustration schematically shows the management according to this disclosure. Figure 1 The control signal for the engine's butterfly valve.
[0034] Figure 6 It shows the relationship with Figure 5 A flowchart example of an implementation method for the corresponding control signal. Detailed Implementation
[0035] Now for reference Figure 1 Those skilled in the art will see here a single-cylinder engine schematically shown in cross-sectional view. Thus, the engine includes a cylinder 2, a piston 4 sliding within the cylinder 2, and a combustion chamber 6 above the piston 4. The piston 4 is connected to the engine flywheel 10 via a connecting rod 8. A position sensor 12 enables the identification of the angular position of the engine flywheel 10 and its rotational speed (RPM), which corresponds to the engine's rotational speed or rotational speed.
[0036] On one hand, fuel is supplied to combustion chamber 6, and on the other hand, fresh air is supplied to it. The fuel inlet conduit, schematically indicated by arrow 14, supplies fuel from injection system 16 into combustion chamber.
[0037] Air is delivered to combustion chamber 6 through intake duct 18. At least one intake valve 20 allows control over the airflow into the combustion chamber. In the following text, it will be assumed that there is only one intake valve 20. The airflow in intake duct 18 is regulated by an electrically operated butterfly valve 22. The space between the electrically operated butterfly valve 22 and combustion chamber 6 (or intake valve 20) in the intake duct is called manifold 24. A pressure sensor 26 allows the detection of pressure in manifold 24.
[0038] In the example shown, the engine is a forced ignition engine ignited by spark plug 28.
[0039] The electronic control unit 30, commonly referred to as the ECU, enables the operation and control of the engine. This unit is specifically connected to the injection system 16, the spark plug 28 (or more generally to the ignition system), the position sensor 12, the pressure sensor 26, and the electric butterfly valve 22 (which also includes at least one papilion position sensor).
[0040] Figure 1 The engine exhaust system is not shown in particular because this disclosure relates more specifically to the intake system in an engine. However, those skilled in the art will recognize the exhaust system and other engine components not shown in this schematic diagram.
[0041] This disclosure relates more particularly to situations where the engine speed (RPM) is low and / or the engine load (L) is also light. Figure 1 The engine operates under these conditions. When fresh air enters, some already burned gases remain in the combustion chamber. In practice, it is generally stipulated that both the exhaust and intake valves are open for a period of time when fresh air begins to enter. At high speeds and / or loads, this allows the fresh air entering the combustion chamber to expel the remaining burned gases. At low speeds and / or light loads, the incoming fresh air does not have enough energy to expel all the burned gases. The mixture in the combustion chamber then partially contains the burned gases, which slows combustion and causes the engine speed to become unstable, meaning the speed varies significantly (and uncontrollably).
[0042] Figure 2 and Figure 3 The prior art according to this disclosure is shown. Figure 1 The engine's normal operation. Figure 2 Curve 100 in the figure shows the pressure in the intake manifold 24, as measured by pressure sensor 26. This pressure increases as long as the intake valve 20 is closed, until it reaches its maximum value (roughly corresponding to atmospheric pressure in a non-turbocharged engine) shortly after the intake valve 20 begins to open. When the engine is operating in a four-stroke cycle, Figure 2 The two maximum pressure values shown are far from 720°CRK.
[0043] Figure 3 The angular position of the butterfly element 32 used to change the cross-section in the intake duct 18 is shown. The butterfly element 32 is mounted to pivot about an axis transverse to the intake duct 18 (and is controlled by the engine), and is considered to pivot between two extreme values, 0° and 90° (which may not be achieved in practice), with 0° corresponding to the minimum possible cross-section and 90° corresponding to the maximum opening, and thus the maximum possible cross-section.
[0044] Hereafter, PAP will be used to refer to the position of the butterfly element 32 within its housing, i.e., within the electric butterfly valve 22. In the prior art of this disclosure, the butterfly element 32 remains at the same angular position MOY throughout the entire engine cycle (intake, compression, power, and exhaust). In the example shown, the value of MOY is, for example, 8°. This angle value is determined by the electronic control unit 30 such that the mass of air entering the combustion chamber 6 corresponds to the mass of fuel, thereby achieving complete combustion of the fuel.
[0045] Inventively, in order to improve the combustion of the engine at low speeds and / or light loads, and in a preferred embodiment variant to improve the combustion of the engine at low speeds and light loads, and in order to improve the combustion stability, the electric butterfly valve 22 is quickly controlled so that the angular position of its butterfly member 32 changes during the combustion cycle or the engine cycle, thereby reducing the passage cross-section of the intake duct when air enters the combustion chamber (compared to the position of the butterfly member 32 during other strokes of the cycle). Thus, this involves changing the position of the butterfly member 32 so that it closes more when air enters the combustion chamber.
[0046] In order to enable the amount (mass) of air entering the combustion chamber to correspond to the amount of fuel injected, it is necessary to adjust the opening angle of the butterfly member 32 other than during the intake stroke.
[0047] Figure 5 Shows the opening control of the butterfly member 32 corresponding to conditions that are similar in all respects to Figure 2 and Figure 3 The engine speed RPM and load L are the same, and it is assumed that the same amount of fuel should be injected. Therefore, the same mass of air should enter the engine.
[0048] Keep in mind that in the Figure 2 and Figure 3 configuration, in order to admit the correct air quality, it has been determined that the butterfly member 32 should open according to the angle PAP = MOY. By way of illustration only and not limitation, for example, PAP = MOY = 8°.
[0049] Under similar conditions, Figure 5 it is proposed to close the butterfly member 32 so that its angular position is PAP = MIN, where MIN < MOY. By way of (non-limiting) illustration, for example, MIN = 5°. The butterfly member 32 adopts this position only when the intake valve 20 is open. When the intake valve 20 is closed, the butterfly member 32 adopts the angular position PAP = MAX, where MAX > MOY. By way of non-limiting illustrative example, for example, MAX = 9°.
[0050] By controlling the electric butterfly valve 22 in this way, it is noted that the pressure curve in the intake manifold 24 has changed. In Figure 4 the curve 200 shows the pressure change in the intake manifold 24 corresponding to this control mode of the electric butterfly valve 22. For the sake of easy comparison, this Figure 4 also shows again Figure 2Curve 100. Notably, just before the intake valve 20 opens, the pressure in the intake manifold 24 is higher than the pressure observed when the disc 32 maintains a constant angular position. This "boost" is approximately 100 millibars. When the intake valve opens, this boost prevents the return of exhaust gases, which are essentially at atmospheric pressure, and also (to a lesser extent) facilitates the entry of fresh air into the combustion chamber. In other words, the fresh air arriving at a higher pressure more effectively expels the exhaust gases from the combustion chamber.
[0051] Generally, the intake valve 20 opens slightly before the piston 4 passes through the corresponding top dead center, and closes after the piston 4 subsequently passes through the bottom dead center. Advantageously, the disc 32 is in its closed position (PAP = MIN) at least between the piston 4 passing through top dead center and the bottom dead center corresponding to the intake.
[0052] The "closed" position of the butterfly component 32 is not a fixed position. This "closed" position depends on the amount of air entering the engine in each cycle. Similarly, the "open" position is not fixed either, but is determined based on the amount of air entering the engine.
[0053] The butterfly element 32 can be positioned within a range of its closed position as described above, for example, a 180° CRK range from top dead center to bottom dead center, during which the intake valve 20 is open.
[0054] This range can vary. It can correspond to the intake valve opening range (e.g., 10° CRK before top dead center to 60° CRK after bottom dead center). It can be smaller than the intake valve opening range, larger than the intake valve opening range, or it can span both the intake valve opening and closing phases. For example, the proposed range of the intake duct cross-section limited by the "closed" position of the butterfly member 32 corresponds to at least 90° CRK during intake valve opening, and advantageously corresponds to at least 135° CRK, and preferably corresponds to at least 180° CRK.
[0055] The foregoing description pertains to a single-cylinder engine. Those skilled in the art will also understand that this description can be applied to an engine comprising multiple cylinders and having an electrically operated butterfly valve (or equivalent) for controlling the amount of airflow supplied to each cylinder.
[0056] Figure 6 This is a flowchart outlining a method according to the present disclosure for achieving stable combustion in an engine at low speeds and light loads.
[0057] The electronic control unit 30 identifies the engine speed RPM and load L. These values are compared with predetermined speed values RPMo and predetermined load values Lo.
[0058] If the rotational speed RPM is higher than RPMo or if the load L is higher than Lo, the electric butterfly valve 22 is controlled so that its butterfly element 32 maintains a constant angular position (PAP = MOY) for each air mass setpoint.
[0059] In contrast, if the engine speed RPM is lower than RPMo and the engine load is lower than Lo, the butterfly element 32 will have a variable angle position for the same air mass setpoint.
[0060] In the simplified embodiment shown here, whether the engine is in the intake stroke is determined based on the engine's angular position (°CRK). If applicable, the electric butterfly valve is controlled to position the butterfly element at angular position PAP = MIN; otherwise, control is sent to position the butterfly element at PAP = MAX.
[0061] Industrial applications
[0062] This technical solution is particularly applicable to the management of internal combustion engines.
[0063] The solution presented in this disclosure enables improvements to engine stability without requiring additional components. The modifications required are purely software-related.
[0064] The proposed solution does not lead to increased fuel consumption. It enables optimized combustion and improves engine efficiency at low speeds and / or light loads.
[0065] Finally, the achievement of engine stability at low speeds and / or light loads did not compromise engine performance.
[0066] This disclosure is not limited to the above-described methods and systems examples and variations thereof, which are merely examples, but covers all variations that would be conceived by those skilled in the art within the framework of the protection sought.
Claims
1. A method for regulating combustion in an internal combustion engine, said engine being a single-cylinder engine or having one throttle valve per cylinder, said engine including, on one hand, an intake manifold (18) provided with a regulating device (22) enabling regulation of airflow in said manifold, and on the other hand, a single cylinder (2) associated with said regulating device (22), said engine operating based on a four-stroke engine cycle, characterized in that, The method includes the following steps: - Determine the engine speed and / or load, and - When the engine speed is below a predetermined value and / or the engine load is below a predetermined value, i.e. when the engine is running at a light load and / or low speed, the regulating device (22) that enables the airflow in the intake manifold (18) to be adjusted is configured such that: during the opening of the intake valve (20) that enables air to be introduced from the intake manifold (18) into the corresponding cylinder (2), or at least during a portion of the opening time, the position of the throttle valve during the engine cycle is temporarily reduced compared to other strokes of the engine cycle. The regulating device (22) that enables the adjustment of airflow in the intake manifold includes a butterfly valve. When the engine is determined to be in the intake stroke based on the engine's angular position, the airflow is reduced by pivoting the butterfly valve without closing it. When the engine speed is lower than a predetermined value and / or the engine load is lower than a predetermined value, the control butterfly valve causes its butterfly element (32) to have a variable angular position relative to the setpoint of the same air mass corresponding to the amount of fuel to be injected. When the intake valve (20) is closed, the angular position of the butterfly member (32) is higher than when the intake valve (20) is open, so that pressure is generated in the air collection pipe between the regulating device (22) and the intake valve (20) before the intake valve (20) is opened.
2. The adjustment method according to claim 1, characterized in that, Reduce the airflow in the intake manifold (18) during a time period corresponding to at least 180°CRK.
3. The adjustment method according to any one of claims 1 to 2, characterized in that, It includes the following steps: - Determine the engine speed and load. - Determine the amount of fuel to be injected and the corresponding air quality. - The average position control of the regulating device (22) used to regulate airflow in the intake manifold is determined, which enables the acquisition of a determined air mass during the engine cycle. - During the opening of the intake valve (20), the position of the regulating device (22) is controlled to temporarily restrict the airflow in the intake manifold compared to the average position, and - When the airflow is unrestricted, the position of the regulating device (22) is controlled so that the airflow in the intake manifold during the engine cycle can provide a certain air quality.
4. The adjustment method according to claim 3, characterized in that, With the intake valve (20) open, airflow in the intake manifold (18) is restricted at least during the 180° CRK period corresponding to the passage from top dead center to the next passage from bottom dead center.
5. A computer program product comprising a series of code instructions, wherein when a computer implements the computer program product, the code instructions are used to implement the combustion regulation method of an internal combustion engine according to any one of claims 1 to 4.
6. A computer adapted to regulate the combustion of an internal combustion engine, the engine including, on one hand, an intake manifold (18) provided with a regulating device (22) enabling regulation of airflow in the manifold, and on the other hand, a single cylinder (2) associated with the regulating device (22), characterized in that, The computer is also adapted to implement each step of the adjustment method according to any one of claims 1 to 4.
7. An internal combustion engine, comprising, on one hand, an intake manifold (18) provided with a regulating device (22) enabling the regulation of airflow within the manifold, and on the other hand, a single cylinder (2) associated with the regulating device (22), characterized in that, The engine also includes the computer (30) according to claim 6.
8. The engine according to claim 7, characterized in that, The regulating device (22) that enables the regulation of airflow in the intake manifold includes an electric butterfly valve.