A control method for realizing rail pressure closed loop based on liquid ammonia pump

Abstract

The application discloses a control method for realizing rail pressure closed loop based on a liquid ammonia pump and belongs to the technical field of liquid ammonia pump control, and solves the technical problem that the existing control method is not applicable to the high-pressure outlet control mode of a fuel pump. The method is as follows: target flow is calculated through PID closed loop control according to target rail pressure and actual rail pressure, the target opening angle of the electromagnetic valve of the liquid ammonia pump is calculated according to the target flow and an angle characteristic curve, the electromagnetic valve of the liquid ammonia pump is accurately driven to open to the target opening angle according to engine phase information and an opening advance angle, accurate control of the flow is realized, and thus the rail pressure closed loop control is completed. The method is applicable to the fuel pump adopting the high-pressure outlet control, and is especially suitable for low-carbon and zero-carbon engines.

Description

Technical Field

[0001] This invention relates to the field of liquid ammonia pump control technology, and more specifically, to a control method for achieving rail pressure closed-loop control based on a liquid ammonia pump. Background Technology

[0002] The current method for controlling the outlet flow of liquid ammonia pumps is to control the flow rate at the high-pressure outlet (400-500 bar) using a peak-hold approach. This technology is relatively new, and there is currently no rail pressure control solution suitable for the corresponding liquid ammonia pump system.

[0003] The signal transmission path for rail pressure control in the current control algorithm is as follows: Figure 1 As shown, the target rail pressure and actual rail pressure are processed through a PID closed loop to output the target flow rate. The flow rate is then converted into a target current through a current characteristic curve. The target current and the actual sampled current are used for current closed-loop control, and the output control duty cycle is used to control the solenoid valve driving the liquid ammonia pump, thereby controlling the accurate flow output of the liquid ammonia pump. However, this technical approach is only applicable to the low-pressure inlet control method of the fuel pump, and there is no corresponding algorithm for the high-pressure outlet control method of the fuel pump. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art. The purpose of the present invention is to provide a control method based on a liquid ammonia pump to achieve rail pressure closed-loop control, which is applicable to the high-pressure outlet control mode of fuel pumps.

[0005] The technical solution of this invention is: a control method for rail pressure closed-loop control based on a liquid ammonia pump. The method calculates and outputs a target flow rate based on the target rail pressure and the actual rail pressure through PID closed-loop control. The target opening angle of the liquid ammonia pump's solenoid valve is calculated based on the target flow rate and angle characteristic curve. Based on engine phase information and the opening advance angle, the solenoid valve of the liquid ammonia pump is accurately driven to open to the target opening angle, thereby achieving accurate flow rate control and completing rail pressure closed-loop control.

[0006] As a further improvement, the angle characteristic curve is obtained by calibration under high pressure outlet control conditions, based on different flow rates corresponding to different opening angles of the solenoid valve of the liquid ammonia pump.

[0007] Furthermore, the high-pressure outlet control condition is that the outlet pressure is equal to 400-500 bar.

[0008] Furthermore, the target flow rate is calculated during the static interruption, and the target opening angle of the solenoid valve of the liquid ammonia pump is calculated based on the output target flow rate and the angle characteristic curve.

[0009] Furthermore, the liquid ammonia pump is a pump with a fixed flow rate within a single stroke.

[0010] Furthermore, the duration of the static interrupt is 10ms.

[0011] Furthermore, the advance angle is 5-10 degrees before the engine phase reaches top dead center.

[0012] Beneficial effects

[0013] Compared with the prior art, the advantages of this invention are as follows: This invention calculates the target opening angle of the solenoid valve of the liquid ammonia pump using the target flow rate and angle characteristic curve. Based on the engine phase information and the opening advance angle, it accurately drives the solenoid valve of the liquid ammonia pump to open to the target opening angle, thereby achieving accurate flow control and completing rail pressure closed-loop control. It is suitable for fuel pumps that use high-pressure outlet control, especially for low-carbon and zero-carbon engines, which can ensure the accuracy of high-pressure outlet control and thus improve combustion efficiency and economy. Attached Figure Description

[0014] Figure 1 This is a flowchart of the existing rail pressure control technology; Figure 2 This is the control flowchart of the present invention. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments shown in the accompanying drawings.

[0016] See Figure 2 A control method based on a liquid ammonia pump to achieve rail pressure closed-loop control is proposed. The method calculates the target flow rate through PID closed-loop control based on the target rail pressure and the actual rail pressure. The target opening angle of the solenoid valve of the liquid ammonia pump is calculated based on the target flow rate and angle characteristic curve. Based on the engine phase information and the opening advance angle, the solenoid valve of the liquid ammonia pump is accurately driven to open to the target opening angle, thereby achieving accurate flow control and completing rail pressure closed-loop control.

[0017] Specifically, the angle characteristic curve is obtained by calibration under high pressure outlet control conditions, based on the different flow rates corresponding to different opening angles of the solenoid valve of the liquid ammonia pump. The high pressure outlet control conditions are an outlet pressure of 400-500 bar, to adapt to fuel pumps using high pressure outlet control.

[0018] Furthermore, the target flow rate is calculated during a static interrupt, and the target opening angle of the solenoid valve of the liquid ammonia pump is calculated based on the output target flow rate versus the angle characteristic curve. That is, a static interrupt program is set up in the ECU specifically to calculate the target opening angle. Accurate and stable actual rail pressure can be obtained during the static interrupt, thus ensuring the accuracy of the target opening angle calculation. The liquid ammonia pump is a single-stroke pump with a fixed flow rate.

[0019] Preferably, the duration of a static interrupt is 10ms.

[0020] The opening advance angle is 5-10 degrees before the engine phase reaches top dead center. That is, the solenoid valve of the liquid ammonia pump is accurately driven to open to the target opening angle 5-10 degrees before the engine phase reaches top dead center. The purpose is to compensate for the influence of the time from the start of the solenoid valve opening to the full opening, so as to ensure the accuracy of control.

[0021] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A control method for rail pressure closed-loop control based on a liquid ammonia pump, wherein the target flow rate is calculated and output through PID closed-loop control based on the target rail pressure and the actual rail pressure, characterized in that... The target opening angle of the solenoid valve of the liquid ammonia pump is calculated based on the target flow rate and angle characteristic curve. Based on the engine phase information and the opening advance angle, the solenoid valve of the liquid ammonia pump is accurately driven to open to the target opening angle, thereby achieving accurate flow rate control and completing the rail pressure closed-loop control.

2. The control method for achieving rail pressure closed-loop based on a liquid ammonia pump according to claim 1, characterized in that, The angular characteristic curve was obtained by calibration under high-pressure outlet control conditions, based on different flow rates corresponding to different opening angles of the solenoid valve of the liquid ammonia pump.

3. The control method for achieving rail pressure closed-loop based on a liquid ammonia pump according to claim 1, characterized in that, The high-pressure outlet control condition is that the outlet pressure is equal to 400-500 bar.

4. A control method for achieving rail pressure closed-loop control based on a liquid ammonia pump according to any one of claims 1-3, characterized in that, The target flow rate is calculated during a static interruption, and the target opening angle of the solenoid valve of the liquid ammonia pump is calculated based on the output target flow rate and the angle characteristic curve.

5. The control method for achieving rail pressure closed-loop based on a liquid ammonia pump according to claim 4, characterized in that, The liquid ammonia pump is a single-stroke pump with a fixed flow rate.

6. The control method for achieving rail pressure closed-loop control based on a liquid ammonia pump according to claim 4, characterized in that, The duration of the static interrupt is 10ms.

7. The control method for achieving rail pressure closed-loop based on a liquid ammonia pump according to claim 1, characterized in that, The advance angle is 5-10 degrees before the engine phase reaches top dead center.

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