A fuel injection control system and method for a single rotor engine

Abstract

A single rotor engine fuel injection control system and method, rotor engine electronic control fuel injection control technical field, including: eccentric shaft position sensor, intake pressure sensor, oxygen sensor, auxiliary sensor, fuel injector and ECU, the eccentric shaft position sensor, intake pressure sensor, oxygen sensor and auxiliary sensor are connected with ECU signal, the ECU is connected with fuel injector signal.The present application is through intake load and air-fuel ratio closed loop accurate calculation fuel quantity, according to eccentric shaft position sensor real-time division each combustion chamber stroke, and according to the speed and load dynamic determination optimum injection phase, realize the accurate control of injection time and injection quantity.

Description

Technical Field

[0001] This invention belongs to the field of electronic fuel injection control technology for rotary engines, and in particular, a fuel injection control system and method for a single-rotor engine. Background Technology

[0002] Wankel engines offer advantages such as compact structure, high power density, and smooth operation. As the most basic structural unit, the single-rotor engine has broad application prospects in areas such as small drones, portable power generation devices, and range-extended electric vehicles.

[0003] However, its unique structure and working principle bring a series of technical challenges to fuel injection control: First, the combustion chamber of a single-rotor engine is formed by the rotor and cylinder. As the rotor moves, each combustion chamber independently completes the intake, compression, power, and exhaust strokes. The area between the cylinders is divided into three independent working chambers. When the triangular rotor rotates in the cylinder, the volume of the three working chambers changes continuously, each sequentially completing the intake, compression, power, and exhaust strokes. The crankshaft angle corresponding to each stroke of the rotor engine is 270°, which is 1.5 times that of a traditional reciprocating piston engine, and the crankshaft angle corresponding to one working cycle is 1080°. This complex phase relationship makes the traditional fuel injection control strategy of reciprocating piston engines unsuitable for direct application. The injection timing must be precisely matched with the intake stroke of each combustion chamber; otherwise, problems such as fuel wetting the walls and uneven air-fuel mixture will occur. Second, existing fuel injection control technologies mostly adopt open-loop control methods, with the fuel injection quantity based on a pre-calibrated basic fuel injection quantity MAP, lacking a real-time feedback correction mechanism. As engine operating time increases, factors such as injector wear, carbon buildup, and changes in fuel quality can cause the actual air-fuel ratio to deviate from the target value, resulting in poor combustion and increased emissions. Third, determining the injection timing typically only considers engine speed, ignoring the impact of load variations on the optimal injection phase. In reality, intake air volume, airflow velocity, and fuel evaporation rate all differ under different loads, making it impossible to achieve optimal combustion performance under all operating conditions with a fixed injection timing.

[0004] Therefore, this invention proposes a fuel injection control system and method for a single-rotor engine. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a single-rotor engine fuel injection control system and method.

[0006] This invention utilizes an eccentric shaft position sensor to divide the stroke of each combustion chamber in real time, accurately calculates the fuel injection quantity based on intake load and closed-loop feedback from the oxygen sensor, and determines the optimal injection phase based on a two-dimensional MAP of speed-load, achieving independent and precise control of injection timing and quantity. This invention solves the problems of low accuracy in open-loop fuel injection quantity control and mismatch between injection timing and combustion chamber stroke in existing technologies, effectively improving fuel atomization and mixture formation, reducing emissions, and improving fuel economy. It is applicable to the electronic control systems of various single-rotor engines.

[0007] The technical solution adopted in this invention is as follows:

[0008] A single-rotor engine fuel injection control system includes: an eccentric shaft position sensor, an intake pressure sensor, an oxygen sensor, an auxiliary sensor, a fuel injector, and an ECU. The eccentric shaft position sensor, the intake pressure sensor, the oxygen sensor, and the auxiliary sensor are all connected to the ECU via signal connection, and the ECU is connected to the fuel injector via signal connection.

[0009] The eccentric shaft position sensor is mounted on the front cover of the single-rotor engine and is used to detect the eccentric shaft rotation angle signal.

[0010] The intake pressure sensor is installed on the intake manifold of the single-rotor engine to obtain the engine intake load.

[0011] An oxygen sensor is installed on the exhaust pipe of a single-rotor engine to detect the oxygen concentration in the exhaust and achieve closed-loop control of the air-fuel ratio.

[0012] The auxiliary sensors include: a coolant temperature sensor, an intake air temperature sensor, a knock sensor, a fuel pressure sensor, and a system voltage sensor. The coolant temperature sensor, intake air temperature sensor, knock sensor, fuel pressure sensor, and system voltage sensor are all connected to the ECU signal. The coolant temperature sensor is installed on the coolant outlet of the rotary engine housing, the intake air temperature sensor is installed on the intake manifold of the rotary engine housing, the knock sensor is installed on the spark plug side of the rotary engine housing, the system voltage sensor is located inside the ECU, and the knock sensor is installed on the rotary engine housing.

[0013] The injector is mounted on the exhaust pipe of the single-rotor engine, and an ignition coil is connected to the injector.

[0014] A method of using a fuel injection control system for a single-rotor engine, the method comprising the following steps:

[0015] S1: Signal acquisition and preprocessing;

[0016] S2: Cavity stroke division;

[0017] S3: Initial fuel injection quantity calculation;

[0018] S4: Fuel injection pulse width calculation;

[0019] S5: Determines the optimal fuel injection phase;

[0020] S6: Fuel injection timing execution;

[0021] S7: Cyclic updates and self-learning.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention accurately calculates fuel quantity through closed-loop calculation of intake load and air-fuel ratio, divides the stroke of each combustion chamber in real time based on the eccentric shaft position sensor, and dynamically determines the optimal injection phase according to speed and load, thereby achieving precise control of injection timing and injection quantity.

[0024] And it solves the following problems existing in the prior art:

[0025] 1. Low precision in fuel injection quantity control: The existing open-loop control method cannot correct the fuel injection quantity deviation in real time, resulting in large fluctuations in the air-fuel ratio, which affects combustion stability and emission performance.

[0026] 2. Mismatch between injection timing and combustion chamber stroke: The lack of real-time identification of the independent strokes of the three combustion chambers of the rotary engine makes it difficult for the injection timing to fall precisely into the intake window of each combustion chamber, which can easily lead to fuel waste and worsened emissions.

[0027] 3. Fixed injection phase: The effect of load changes on the optimal injection timing is not considered, and optimal combustion cannot be achieved under all operating conditions. Attached Figure Description

[0028] Figure 1 Schematic diagram of the fuel injection system layout for a single-rotor engine;

[0029] Figure 2 Flowchart of fuel injection control method for a single-rotor engine;

[0030] Figure 3 Example diagram of fuel injection timing for a single-rotor engine;

[0031] Figure 4 This is a schematic diagram of an eccentric shaft position sensor. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Combination Figure 1-4 The invention relates to a single-rotor engine fuel injection control system, comprising: an eccentric shaft position sensor, an intake air pressure sensor, an oxygen sensor, an auxiliary sensor, a fuel injector, and an ECU. The eccentric shaft position sensor, the intake air pressure sensor, the oxygen sensor, and the auxiliary sensor are all connected to the ECU via signal connection, and the ECU is connected to the fuel injector via signal connection.

[0034] The eccentric shaft position sensor is mounted on the front cover of the single-rotor engine and is used to detect the eccentric shaft rotation angle signal.

[0035] The intake pressure sensor is installed on the intake manifold of the single-rotor engine to obtain the engine intake load.

[0036] An oxygen sensor is installed on the exhaust pipe of a single-rotor engine to detect the oxygen concentration in the exhaust and achieve closed-loop control of the air-fuel ratio.

[0037] The auxiliary sensors include: a coolant temperature sensor, an intake air temperature sensor, a knock sensor, a fuel pressure sensor, and a system voltage sensor. The coolant temperature sensor, intake air temperature sensor, knock sensor, fuel pressure sensor, and system voltage sensor are all connected to the ECU signal. The coolant temperature sensor is installed on the coolant outlet of the rotary engine housing, the intake air temperature sensor is installed on the intake manifold of the rotary engine housing, the knock sensor is installed on the spark plug side of the rotary engine housing, the system voltage sensor is located inside the ECU, and the knock sensor is installed on the rotary engine housing.

[0038] The injector is mounted on the exhaust pipe of the single-rotor engine, and an ignition coil is connected to the injector.

[0039] Furthermore, the ECU integrates the following modules: a signal acquisition module, a cavity stroke division module, a fuel quantity calculation module, a fuel injection phase determination module, a fuel injection drive module, and a communication and calibration module.

[0040] A method of using a fuel injection control system for a single-rotor engine, the method comprising the following steps:

[0041] S1: Signal acquisition and preprocessing;

[0042] The ECU collects signals from various sensors in real time and performs filtering and normalization. It acquires the eccentric shaft angle signal through an eccentric shaft position sensor, obtains the intake air load through an intake pressure sensor, and collects the oxygen concentration in the exhaust gas through an oxygen sensor to achieve closed-loop air-fuel ratio control. A broadband oxygen sensor is preferred, which can continuously measure the excess air coefficient λ. Other auxiliary sensors acquire parameters such as coolant temperature, intake air temperature, knock status, fuel pressure, and system voltage.

[0043] S2: Cavity stroke division;

[0044] As attached Figure 4 As shown, the current stroke of the three combustion chambers is calculated based on the eccentric shaft position. The eccentric shaft position signal wheel has 30 teeth, with three toothless areas. The angle between two tooth slots is 10°, and the angle between two openings in the toothless areas is 30°. The change in magnetic induction intensity of the magnetic induction coil located in the eccentric shaft position sensor is sent as a voltage value to the ECU. When the eccentric shaft position sensor is removed, installed, or replaced, the magnetic induction intensity of the electromagnetic induction coil is disturbed. If magnetic materials, such as iron powder, are attached to the sensor, it will cause abnormal sensor output, which will in turn affect engine control. The eccentric shaft position sensor detects the rotation pulses of the eccentric shaft position plate as the eccentric shaft angle signal, as shown in the attached diagram. Figure 4 As shown. The sensor adopts a fully sealed structure, with good moisture and dust resistance, long service life, and fast response, which can meet the high-speed control requirements of rotary engines. Through this symmetrical arrangement of missing teeth-signal theory, cylinder and chamber stroke division can be quickly completed. The eccentric shaft position sensor can detect the missing tooth position every half revolution, generating an interrupt voltage signal at 180° intervals.

[0045] S3: Initial fuel injection quantity calculation;

[0046] Fuel quantity calculation is divided into two parts: open-loop base quantity and closed-loop correction. The base fuel quantity is calculated by referring to a preset 3D MAP of the base fuel quantity, obtaining the basic injection mass Q_base (unit: mg / cycle) per chamber per cycle. Closed-loop correction refers to using a PID control algorithm to calculate an air-fuel ratio closed-loop correction coefficient K_afr based on the oxygen sensor signal. The target fuel quantity is obtained by multiplying the base fuel quantity by the closed-loop correction coefficient. The formula is:

[0047] K_afr = K_p e_afr + K_i ∫e_afr dt + K_d de_afr / dt

[0048] Where e_afr = λ_target - λ_actual, λ_target is the target excess air coefficient (usually 1 for gasoline engines), and λ_actual is the oxygen sensor feedback value.

[0049] S4: Fuel injection pulse width calculation;

[0050] The formula for calculating the injection pulse width T_inj based on the target fuel quantity and injector characteristics is as follows:

[0051] T_inj = Air_den V / Lst 1.05 Q_stat

[0052] Where: Air_den is air density (g / dm³); V is engine displacement (dm³); 1.05 is fuel correction factor; Q_stat is injector static flow rate (g / min); Lst is stoichiometric air-fuel ratio.

[0053] S5: Determines the optimal fuel injection phase;

[0054] The fuel injection timing diagram for the single-rotor engine is attached. Figure 3 As shown, the optimal injection phase θ_inj is obtained by querying the optimal injection phase MAP diagram with engine speed and load (or intake pressure) as inputs.

[0055] S6: Fuel injection timing execution;

[0056] For the combustion chamber about to enter the intake stroke, the ECU monitors the eccentric shaft angle in real time. When the eccentric shaft angle of the combustion chamber (relative to the chamber's TDC) reaches θ_inj, the ECU outputs a fuel injection drive signal to open the fuel injector, which lasts for T_inj. It is necessary to ensure that the fuel injection ends no later than the intake stroke closing angle of the chamber (to avoid fuel back-injection); otherwise, a limiting effect is applied.

[0057] During the fuel injection process, the ECU monitors the working status of the fuel injectors through the current detection circuit. If any abnormality (short circuit, open circuit) is detected, a fault code is recorded.

[0058] S7: Cyclic updates and self-learning.

[0059] After each chamber completes one injection, the status is updated, and steps S3-S6 are repeated to achieve independent closed-loop control for each cylinder.

[0060] For the other two combustion chambers, the ECU will repeat steps S3-S7 within their respective intake windows. Since the intake windows of the three combustion chambers are spaced 360° apart, the ECU can process them sequentially without any conflict.

[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A fuel injection control system for a single-rotor engine, characterized in that: include: The system includes an eccentric shaft position sensor, an intake pressure sensor, an oxygen sensor, an auxiliary sensor, a fuel injector, and an ECU. The eccentric shaft position sensor, intake pressure sensor, oxygen sensor, and auxiliary sensor are all connected to the ECU via signal transmission, and the ECU is connected to the fuel injector via signal transmission.

2. The fuel injection control system for a single-rotor engine according to claim 1, characterized in that: The eccentric shaft position sensor is mounted on the front cover of the single-rotor engine and is used to detect the eccentric shaft rotation angle signal.

3. The fuel injection control system for a single-rotor engine according to claim 1, characterized in that: The intake pressure sensor is installed on the intake manifold of the single-rotor engine to obtain the engine intake load.

4. The fuel injection control system for a single-rotor engine according to claim 1, characterized in that: An oxygen sensor is installed on the exhaust pipe of a single-rotor engine to detect the oxygen concentration in the exhaust and achieve closed-loop control of the air-fuel ratio.

5. A single-rotor engine fuel injection control system according to claim 1, characterized in that: The auxiliary sensors include: a coolant temperature sensor, an intake air temperature sensor, a knock sensor, a fuel pressure sensor, and a system voltage sensor. The coolant temperature sensor, intake air temperature sensor, knock sensor, fuel pressure sensor, and system voltage sensor are all connected to the ECU signal. The coolant temperature sensor is installed on the coolant outlet of the rotary engine housing, the intake air temperature sensor is installed on the intake manifold of the rotary engine housing, the knock sensor is installed on the spark plug side of the rotary engine housing, the system voltage sensor is located inside the ECU, and the knock sensor is installed on the rotary engine housing.

6. The fuel injection control system for a single-rotor engine according to claim 1, characterized in that: The injector is mounted on the exhaust pipe of the single-rotor engine, and an ignition coil is connected to the injector.

7. A method of using the single-rotor engine fuel injection control system according to any one of claims 1-6, characterized in that: The method includes the following steps: S1: Signal acquisition and preprocessing; S2: Cavity stroke division; S3: Initial fuel injection quantity calculation; S4: Fuel injection pulse width calculation; S5: Determining the optimal fuel injection phase; S6: Fuel injection timing execution; S7: Cyclic updates and self-learning.

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