CN-122014401-A - Control method of two-stroke electromechanical auxiliary two-stage supercharging system with opposed pistons

CN122014401ACN 122014401 ACN122014401 ACN 122014401ACN-122014401-A

Abstract

The application provides a control method of an electric auxiliary two-stage supercharging system of an opposite piston two-stroke diesel engine, which comprises the steps of collecting engine signals through a sensor network and carrying out signal preprocessing, wherein the engine signals comprise a rotating speed signal, a load signal, a scavenging pressure signal, a turbine front exhaust pressure signal and a scavenging temperature signal, according to the rotating speed and the load parameters of the engine, and based on the required scavenging pressure and the natural capability of the turbine determined by a simulation test, different working conditions of the diesel engine are subjected to mode division, and according to the divided working modes under the different working conditions, a control strategy corresponding to the working modes is executed to dynamically coordinate the working states of the electric supercharger and an auxiliary motor. The application solves the starting problem of the OP2S diesel engine and the scavenging deficiency problem caused by low air inlet pressure in the low-speed working condition, realizes high-efficiency pressurization and quick response in the full working condition range, and realizes the optimal system level energy efficiency through intelligent energy management.

Inventors

Bo Yaqing
LIANG YONGSEN
LI HONG
SHI DAYU
WANG LIANCHUN
PU BOWEN
Su liwang

Assignees

中国北方发动机研究所

Dates

Publication Date: 20260512
Application Date: 20260310

Claims (10)

1. A method for controlling an opposed-piston two-stroke electromechanical auxiliary two-stage supercharging system, comprising: Collecting engine signals through a sensor network and performing signal preprocessing, wherein the engine signals comprise a rotating speed signal, a load signal, a scavenging pressure signal, a turbine front exhaust pressure signal and a scavenging temperature signal; According to the engine speed and load parameters, and based on the scavenging pressure required and the natural capability of the turbine determined by a simulation test, carrying out mode division on different working conditions of the diesel engine; And executing a control strategy corresponding to the working modes according to the working modes divided under different working conditions to dynamically coordinate the working states of the electric supercharger and the auxiliary motor, wherein the control strategy comprises obtaining intake mass flow according to the processed scavenging pressure, the turbine front exhaust pressure and the scavenging temperature, determining an optimal pressure ratio under the current flow based on the intake mass flow, determining a first-stage outlet boundary according to the optimal pressure ratio and the target scavenging pressure calibrated in advance, and further adjusting the electric supercharger and the auxiliary motor.
2. The method according to claim 1, characterized in that: obtaining a required scavenging pressure through a simulated supercharging test; and obtaining a compressor characteristic diagram and a turbine characteristic diagram through a turbine and compressor component test, and obtaining the natural capability of the turbine through inquiring the compressor characteristic diagram and the turbine characteristic diagram according to the exhaust pressure and the air flow parameters.
3. The method according to claim 1, characterized in that: determining a preferable mode under different rotating speeds and load conditions according to the required scavenging pressure and the natural capability of the turbine, wherein the method comprises the following steps: responding to the condition that the required scavenging pressure is larger than the natural capability of the turbine and the temperature of the exhaust gas before the turbine is smaller than or equal to a temperature threshold value so as to judge that the pure supercharging mode is entered; Responsive to the demand scavenge pressure being greater than the turbine natural capability and the pre-turbine exhaust gas temperature being greater than a temperature threshold, determining to enter a combined boost mode; Responsive to the demand scavenge pressure approaching the turbine natural ability to determine to enter a main turbo boost mode; responsive to the demand scavenge pressure being less than the turbine natural ability, determining to enter an energy recovery mode.
4. A method according to claim 3, wherein the control strategy comprises: For a pure supercharging mode, determining the boundary of the first-stage outlet as a target scavenging pressure calibrated in advance; For the turbo main supercharging mode and the energy recovery mode, the electric supercharger does not participate in work, and the boundary of the first-stage outlet is determined to be the atmospheric pressure; And for the combined supercharging mode, inquiring a compressor characteristic diagram according to the air inlet mass flow rate so as to determine an optimal pressure ratio under the current flow rate, and determining a first-stage outlet boundary according to the optimal pressure ratio and a target scavenging pressure calibrated in advance.
5. The method of claim 4, wherein the intake mass flow formula is as follows: ; Wherein, the ; In the formula, Is the intake mass flow; And Respectively a flow coefficient and an equivalent flow area; Is the density of the inlet air; is the scavenging pressure; Is turbine front exhaust pressure; Is the scavenging temperature; Is a gas constant.
6. The method as recited in claim 4, further comprising: For the pure supercharging mode, the outlet pressure of the electric supercharger is the target scavenging pressure of the engine, and the pressure ratio of the electric supercharger is obtained through calculation according to the atmospheric pressure; For the combined boost mode, the electric supercharger outlet pressure is the first stage outlet boundary (turbocharger scavenging pressure), and the electric supercharger pressure ratio is calculated according to the atmospheric pressure; And obtaining a target rotating speed by inquiring an electric booster characteristic diagram according to the current intake mass flow and the electric booster pressure ratio so as to control the electric booster motor to reach the target rotating speed.
7. The method as recited in claim 4, further comprising: According to the current air inlet mass flow and the optimal pressure ratio, obtaining the power required by driving the air compressor by inquiring the characteristic diagram of the air compressor; And inquiring a turbine characteristic diagram according to the current exhaust mass flow, the turbine front exhaust temperature and the turbine front exhaust pressure to obtain the effective power actually output by the turbine under the current exhaust energy so as to determine an auxiliary motor instruction, wherein the current exhaust mass flow is calculated according to the air inlet mass flow and the fuel injection mass flow.
8. The method according to claim 7, wherein: For the combined supercharging mode, determining a power gap according to the power required by the compressor and the effective power output by the turbine, wherein the power gap is the power to be output by the auxiliary motor; and for the energy recovery mode, determining the surplus power of the power according to the power required by the compressor and the effective power output by the turbine, and recovering the energy by using an auxiliary motor.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of any of claims 1-8 when the program is executed by the processor.
10. A non-transitory computer readable storage medium, wherein the non-transitory computer readable storage medium stores computer instructions for causing a computer to perform the method of any one of claims 1-8.

Description

Control method of two-stroke electromechanical auxiliary two-stage supercharging system with opposed pistons Technical Field The application belongs to the technical field of supercharging of internal combustion engines, and particularly relates to a control method of an electric auxiliary two-stage supercharging system of an opposed-piston two-stroke diesel engine. Background The two-stroke diesel engine with opposite pistons, which has the advantages of high power density, high mechanical efficiency, small heat loss and the like, has wide application prospect in the fields of vehicles, ship power and special equipment. However, the scavenging process of OP2S diesel engines relies solely on the intake and exhaust pressure differential provided by the supercharging system, unlike conventional two-stroke, four-stroke engines, which rely on the crankcase to provide intake and exhaust pressure differential, which in turn have separate exhaust and intake strokes, which makes OP2S engines much more sensitive to the performance of the supercharging system than conventional engines. Thus, the core technical challenges faced by OP2S diesel engines include: (1) The starting is difficult, the scavenging process of the OP2S diesel engine completely depends on the air inlet and outlet pressure difference provided by the supercharging system, and the diesel engine can not be started in a mode of dragging the diesel engine directly by the motor under the condition that the air inlet and outlet pressure difference is not provided by the supercharger; (2) The low-speed scavenging is difficult, namely, under the working condition of low speed and low load, the turbine rotating speed is low due to insufficient energy of exhaust gas, the outlet pressure of a gas compressor is insufficient, and an effective scavenging pressure difference cannot be established, so that scavenging is incomplete, combustion is deteriorated, and carbon smoke emission is increased rapidly; (3) The performance of high rotation speed is difficult to improve, the pressure before vortex is higher at the high rotation speed, and in order to ensure the power of the diesel engine at the high rotation speed, the pressure difference between the air inlet pressure and the air outlet pressure is required to be higher, so that the sufficient scavenging is ensured. However, high intake pressure results in excessive in-cylinder explosion pressure, limiting the boost of diesel engine power. The prior art has obvious defects aiming at the problems, and the traditional two-stage turbocharging system can widen the flow range, but is still a pure passive system, so that the starting problem and the scavenging problem at the extremely low rotating speed can not be solved. The simple electric booster has quick response, but lacks an energy recovery mechanism, so that the system has low energy efficiency. However, the conventional electrically assisted turbo charging technique has a limited auxiliary effect because the turbine itself hardly works at an extremely low engine speed. More importantly, the prior art is mostly developed for traditional four-stroke engines or ordinary two-stroke engines, and lacks a customized solution specifically for the special scavenging requirements of OP2S diesel engines. Disclosure of Invention In view of the above, the present application is directed to a control method for an electro-mechanical auxiliary two-stage supercharging system of an opposed-piston two-stroke diesel engine, which solves at least one of the above-mentioned problems. In order to achieve the above purpose, the technical scheme of the application is realized as follows: in a first aspect, the present application provides a method of controlling an opposed-piston two-stroke electro-mechanical auxiliary two-stage supercharging system, comprising: Collecting engine signals through a sensor network and performing signal preprocessing, wherein the engine signals comprise a rotating speed signal, a load signal, a scavenging pressure signal, a turbine front exhaust pressure signal and a scavenging temperature signal; According to the engine speed and load parameters, and based on the scavenging pressure required and the natural capability of the turbine determined by a simulation test, carrying out mode division on different working conditions of the diesel engine; And executing a control strategy corresponding to the working modes according to the working modes divided under different working conditions to dynamically coordinate the working states of the electric supercharger and the auxiliary motor, wherein the control strategy comprises obtaining intake mass flow according to the processed scavenging pressure, the turbine front exhaust pressure and the scavenging temperature, determining an optimal pressure ratio under the current flow based on the intake mass flow, determining a first-stage outlet boundary according to the optimal pressure ratio and the target scaveng