A closed loop fuel control system based on crankcase pressure balance

Abstract

The utility model discloses a closed loop fuel control system based on crankcase pressure balance. The system introduces the dynamic changing crankcase mixed gas pressure into the fuel regulator as its pressure balance reference, and combines the closed loop feedback of fuel pressure sensor, thereby realizing the high accuracy, self -adaptation adjustment of fuel pressure, guaranteeing the accuracy and consistency of fuel injection quantity of fuel injector, and improving the performance of engine under all working conditions.

Description

Technical Field

[0001] This utility model relates to the field of internal combustion engine fuel supply technology, and in particular to a closed-loop fuel control system based on crankcase pressure balance. Background Technology

[0002] Traditional fuel control systems typically employ mechanical or open-loop electronic control methods. Mechanical fuel regulators are complex in structure, requiring extremely sophisticated design to achieve high-precision control or adaptability to various operating conditions, resulting in high costs and difficult adjustments. While existing electronic fuel control systems offer improved control precision, their fuel pressure regulation reference pressure is mostly constant atmospheric pressure or engine intake manifold pressure.

[0003] However, for certain types of engines, such as two-stroke aircraft piston engines, the crankcase contains a mixture of fuel, oil, air, and exhaust gases. The pressure of this mixture is not constant but fluctuates dramatically with engine operating conditions (such as changes in ambient pressure due to altitude, load, and engine speed). If fuel pressure regulation is based on a fixed atmospheric pressure or intake manifold pressure with varying patterns, the actual pressure difference between the fuel pressure and the pressure inside the engine crankcase will not remain stable. This unstable pressure difference directly affects the fuel injection quantity, causing it to deviate from the expected value, thus impacting engine combustion efficiency, power output, and emissions performance. This problem is particularly pronounced in low-pressure environments such as high altitudes.

[0004] Therefore, existing technologies suffer from insufficient fuel pressure control precision and poor adaptability to engine operating conditions, necessitating a high-precision fuel control system that can adapt to dynamic changes in the internal pressure environment of the engine. Summary of the Invention

[0005] The purpose of this utility model The purpose of this invention is to overcome the shortcomings of existing technologies and provide a closed-loop fuel control system based on crankcase pressure balance. This system introduces dynamically changing crankcase air-fuel mixture pressure into the fuel regulator as its pressure balance reference, and combines this with closed-loop feedback from a fuel pressure sensor to achieve high-precision, adaptive adjustment of fuel pressure. This ensures the accuracy and consistency of fuel injection quantity, improving engine performance under all operating conditions.

[0006] To achieve the above objectives, the technical solution adopted by this utility model A closed-loop fuel control system based on crankcase pressure balance, characterized in that it includes: The fuel supply circuit includes a fuel tank, a fuel pump, a fuel rail, and a fuel regulator connected in sequence via a fuel line. The fuel supply circuit eventually returns fuel to the fuel tank, forming a closed-loop fuel circulation circuit. The sensor detection unit includes a fuel pressure sensor installed at the outlet end of the fuel regulator for real-time monitoring of the fuel pressure output by the fuel regulator. The electronic control unit (ECU) is electrically connected to the fuel pressure sensor and the fuel pump. The fuel regulator is provided with a reference pressure interface, which is connected to the inside of the engine crankcase through a pipeline, so that the air-fuel mixture pressure in the crankcase can act on the internal pressure sensitive element of the fuel regulator as a dynamic balance reference pressure for regulating fuel pressure. The ECU is configured to receive the pressure signal from the fuel pressure sensor, compare it with a preset target pressure value, and generate a control signal based on the comparison result to drive the fuel pump to adjust its working state, thereby achieving closed-loop feedback control of the system fuel pressure.

[0007] More preferably, the fuel regulator is a diaphragm structure, with one side of the diaphragm receiving the air-fuel mixture pressure from the crankcase through the reference pressure interface, and the other side receiving the fuel pressure from the fuel pump. The pressure difference between the two sides of the diaphragm is dynamically stabilized by adjusting the return fuel volume. At the same time, the ECU controls the working state of the fuel pump to achieve precise closed-loop control of the system fuel pressure.

[0008] More preferably, the internal control logic of the ECU is a PID (proportional-integral-derivative) control algorithm or other advanced control algorithms (such as fuzzy control, adaptive control) to achieve fast, smooth and zero steady-state error pressure regulation, effectively suppressing system overshoot and oscillation.

[0009] More preferably, one or more electronic fuel injectors controlled by the ECU are connected to the fuel rail.

[0010] More preferably, the system is suitable for two-stroke aircraft piston engines or high-performance internal combustion engines.

[0011] Beneficial effects of this utility model Compared with the prior art, the advantages and positive effects of this utility model are as follows: High control precision and good closed-loop reliability: The system pressure is monitored in real time by a fuel pressure sensor and fed back to the ECU. The ECU then controls the fuel pump for precise compensation and adjustment, forming a closed-loop control system. This design not only corrects the steady-state error of the system but also responds quickly to dynamic changes in fuel demand, improving the system's robustness and reliability and ensuring the accuracy of fuel injection.

[0012] Highly adaptive and adaptable to various operating conditions: The system innovatively incorporates crankcase pressure as a balancing reference for fuel pressure, allowing fuel pressure to automatically follow changes in crankcase pressure. This means the system can automatically compensate for crankcase pressure fluctuations caused by changes in altitude, engine load, and engine speed, ensuring the engine receives optimal fuel supply pressure under any conditions, significantly improving engine performance stability and high-altitude adaptability.

[0013] The structural improvements are ingenious and the results are remarkable: This utility model only makes key local improvements to the traditional fuel system structure (adding crankcase pressure pipes and optimizing control logic), but solves the core problem of engine operating condition adaptability. The cost increase is limited, but the performance improvement is significant, which has high practical value and promotion prospects. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the system structure principle of this utility model; Attached reference numerals: 1-Fuel tank; 2-Fuel pump; 3-Fuel rail; 4-Electronic fuel injector; 5-Fuel regulator; 6-Reference pressure port; 7-Engine crankcase; 8-Fuel pressure sensor; 9-Electronic control unit (ECU). Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0016] like Figure 1 As shown, the closed-loop fuel control system based on crankcase pressure balance provided by this utility model has the following working process: Fuel is pumped from fuel tank 1 by fuel pump 2, and the pressurized fuel flows through fuel rail 3. One or more electronic fuel injectors 4 are installed on fuel rail 3. ECU 9 controls the opening and closing of fuel injectors 4 according to engine operating parameters (such as engine speed, throttle position, etc.) to inject fuel into the engine cylinders.

[0017] The core improvement of the system lies in the fuel regulator 5 and its control logic. The fuel regulator 5 is equipped with a reference pressure interface 6, which is connected to the internal space of the engine's crankcase 7 via an oil-resistant and pressure-resistant pipe. In this way, the air-fuel mixture pressure inside the crankcase 7, which fluctuates drastically with operating conditions, is introduced to the diaphragm side of the fuel regulator 5 in real time.

[0018] Meanwhile, fuel pressure sensor 8 monitors the fuel pressure in fuel rail 3 in real time and transmits the pressure signal to ECU 9. ECU 9 stores a target fuel pressure value set according to engine operating conditions (MAP). ECU 9 compares the received actual pressure signal with the target value and calculates the pressure deviation.

[0019] Subsequently, based on this deviation, ECU 9 generates a corresponding control signal (e.g., adjusting the PWM duty cycle supplied to oil pump 2) through its internal PID control algorithm, driving oil pump 2 to change its output flow rate or pressure. For example, when the actual pressure is lower than the target value, ECU 9 will instruct oil pump 2 to increase its output, thereby increasing the system oil pressure; conversely, it will decrease its output.

[0020] In this process, the fuel regulator 5, acting as a mechanical-hydraulic servo mechanism, moves its diaphragm under the combined action of crankcase pressure (reference side) and fuel pressure (fuel side), assisting in stabilizing fuel pressure by adjusting the return fuel volume. The electronic closed loop formed by ECU9 and fuel pump 2 provides a higher level and more precise active control. Working together, they ensure that the fuel pressure acting on both ends of injector 4 and the pressure inside crankcase 7 maintain a stable and ideal pressure difference, thus guaranteeing accurate fuel injection.

[0021] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in this utility model, based on the technical solution and inventive concept of this utility model, should be included within the protection scope of this utility model.

Claims

1. A closed loop fuel control system based on crankcase pressure balance, characterized by, include: The fuel supply circuit includes a fuel tank (1), a fuel pump (2), a fuel rail (3) and a fuel regulator (5) connected in sequence through a fuel line. The fuel supply circuit eventually returns fuel to the fuel tank (1), forming a closed-loop fuel circulation circuit. The sensor detection unit includes a fuel pressure sensor (8) installed at the outlet end of the fuel regulator (5) for real-time monitoring of the fuel pressure output by the fuel regulator (5). The electronic control unit (ECU) (9) is electrically connected to the fuel pressure sensor (8) and the fuel pump (2); The fuel regulator (5) is provided with a reference pressure interface (6), which is connected to the inside of the crankcase (7) of the engine through a pipeline, so that the air-fuel mixture pressure in the crankcase (7) can act on the internal pressure sensitive element of the fuel regulator (5) as a dynamic balance reference pressure for regulating fuel pressure. The ECU (9) is configured to receive the pressure signal from the fuel pressure sensor (8), compare it with a preset target pressure value, and generate a control signal based on the comparison result to drive the oil pump (2) to adjust its working state, thereby realizing closed-loop feedback control of the system fuel pressure.

2. The closed-loop fuel control system based on crankcase pressure balance according to claim 1, characterized in that, The fuel regulator (5) is a diaphragm structure. One side of the diaphragm introduces the air-fuel mixture pressure from the crankcase (7) through the reference pressure interface (6), while the other side bears the fuel pressure from the oil pump (2). The pressure difference between the two sides of the diaphragm is dynamically stabilized by adjusting the return oil volume. At the same time, the ECU controls the working state of the oil pump to achieve precise closed-loop control of the system fuel pressure.

3. A closed-loop fuel control system based on crankcase pressure balance according to claim 1 or 2, characterized in that, The internal pressure control logic of the ECU (9) adopts a PID control algorithm to achieve fast, stable and zero steady-state pressure regulation.

4. A closed-loop fuel control system based on crankcase pressure balance according to claim 1, characterized in that, One or more electronic fuel injectors (4) controlled by the ECU (9) are connected to the fuel rail (3).

5. A closed-loop fuel control system based on crankcase pressure balance according to claim 1, characterized in that, The system is suitable for two-stroke aero piston engines or high-performance internal combustion engines.

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