CN112780404B

CN112780404B - Single-row air supplement device and method for high-power V-shaped marine diesel engine

Info

Publication number: CN112780404B
Application number: CN202110239308.1A
Authority: CN
Inventors: 杨立平; 聂昊鹏; 王立媛; 安晨
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2021-03-04
Filing date: 2021-03-04
Publication date: 2022-03-18
Anticipated expiration: 2041-03-04
Also published as: CN112780404A

Abstract

The invention aims to provide a single-row air supplement device and method for a high-power V-shaped marine diesel engine, which comprise an A-row cylinder, a B-row cylinder, a basic turbocharger, a controlled turbocharger and a high-pressure compressed air source, wherein an A-row air inlet main pipe is connected with an air collecting cavity, the air collecting cavity is connected with the A-row cylinder, the high-pressure compressed air source is connected with a main air supplement pipe, the main air supplement pipe is connected with the air collecting cavity, a B-row exhaust main pipe between a turbine of the controlled turbocharger and a communicating pipe is provided with a waste gas valve, a B-row air inlet main pipe is provided with an air valve, the main air supplement pipe is provided with a main air supplement valve, and the waste gas valve, the air valve and the main air supplement valve are respectively connected with a control unit. The invention adopts the gas collecting cavity to connect the gas inlet channels of the cylinders and independently controls the gas supply of each cylinder, thereby obviously solving the problems of insufficient air inlet of each cylinder of the engine, combustion deterioration and the like caused by the reduction of air flow in the dynamic process when the high-power V-shaped diesel engine is in the row-breaking work of the low-load cylinder.

Description

Single-row air supplement device and method for high-power V-shaped marine diesel engine

Technical Field

The invention relates to a diesel engine device and a control method, in particular to an air inlet and exhaust device of a marine diesel engine and a control method.

Background

With the upsizing of ships, the high-power V-type supercharged engine is more and more widely applied. When the ship is in a cruising stage, the power demand is very low, when the ship runs under low load, all cylinders do not need to run simultaneously to ensure the power, and if all the cylinders are put into use, the oil consumption of the diesel engine is higher, and the efficiency is very low. Aiming at the problem that the performance of the engine is poor due to the fact that all cylinders are put into use under low load, a method of stopping oil injection of one side of the cylinder is adopted, namely a cylinder bank breaking mode is adopted to solve the problem.

However, under low load, when the engine cylinder is in row-breaking operation, when extreme weather, reverse flow and other conditions are met, the ship needs to accelerate sailing, the load of the engine can be suddenly increased, but it is not worth to put all the cylinders of the engine into use, so that the load can be suddenly increased, and at this time, the phenomenon that the air intake of the cylinder on one side of the engine in operation is insufficient in the dynamic process can be caused, so that the problems of black smoke emission and the like in the combustion process in the cylinder can be caused, and the performance of the engine is deteriorated. The invention provides a single-row air supplement device and a single-row air supplement method for a high-power V-shaped marine diesel engine.

At present, the research on the air supplement device of the supercharged diesel engine still has many defects, and the response speed and uniformity of air supplement have great influence on the air supplement effect. Patent CN203035338U discloses a sequential pressurization structure with air supply function, which only connects a high-pressure compressed air source with a communicating pipe between two air inlet manifolds, so that the stroke of the supplied air to each cylinder is long, the loss of air supply energy is easily caused, and the air supply effect is poor; and because the positions of the cylinders are different, the pressure fluctuation of the supplementary air reaching the cylinders through the air inlet main pipe is large, and the uniformity of air supplement of the cylinders cannot be met. Patent CN103016139A discloses a sequential supercharging and air-supplementing device and method for a diesel engine, and the air-supplementing distributor designed by the invention can only distribute the supplementing air to each cylinder, and cannot independently control the on and off of the air-supplementing entering each cylinder.

Disclosure of Invention

The invention aims to provide a single-row air supplement device and an air supplement method for a high-power V-shaped marine diesel engine, which can solve the problems of insufficient air input caused by sudden acceleration loading of an engine when the cylinder is in a low-load working condition and the air cylinder is in a row-breaking operation, uneven air supplement, poor precision and the like.

The purpose of the invention is realized as follows:

the invention relates to a single-row air supplement device of a high-power V-shaped marine diesel engine, which is characterized in that: the system comprises an A-row cylinder, a B-row cylinder, a basic turbocharger, a controlled turbocharger and a high-pressure compressed gas source, wherein a turbine of the basic turbocharger is connected with an A-row exhaust manifold, the A-row exhaust manifold is connected with the A-row cylinder, a gas compressor of the basic turbocharger is connected with an A-row gas inlet manifold, the A-row gas inlet manifold is connected with a gas collecting cavity, the gas collecting cavity is connected with the A-row cylinder, the high-pressure compressed gas source is connected with a main gas supplementing pipe, the main gas supplementing pipe is connected with the gas collecting cavity, a turbine of the controlled turbocharger is connected with a B-row exhaust manifold, the gas compressor of the controlled turbocharger is connected with a B-row gas inlet pipe, the A-row gas inlet manifold is communicated with the B-row gas inlet manifold, the A-row exhaust manifold is communicated with the B-row exhaust manifold through a communicating pipe, a waste gas valve is arranged on the A-row exhaust manifold between the turbine of the controlled turbocharger and the communicating pipe, an air valve is arranged on the B-row gas inlet manifold, a main gas supplementing pipe is provided with a main gas supplementing valve, a waste gas valve, The air valve and the main gulp valve are respectively connected with the control unit.

The single-row air supplement device of the high-power V-shaped marine diesel engine can also comprise:

1. the gas collecting cavity is connected with a gas supplementing pipe through the gas injection valves, the gas supplementing pipe extends into the corresponding A-row gas inlet manifold to the front of the gas inlet valve, a high-pressure nozzle is installed at the end part of the gas supplementing pipe, and all the gas injection valves are respectively connected with the control unit.

2. The volume of the gas collection cavity is 100-105 times of the air inlet flow of the air supply pipe.

A single-row air supplement method for a high-power V-shaped marine diesel engine is characterized by comprising the following steps: when the low-load cylinder is in the exhaust-blocking operation, a rotating speed sensor arranged on a crankshaft detects the rotating speed of the engine in real time, and sets a target rotating speed change rate n needing air supplement₁When the rotation speed sensor detects that the real-time rotation speed change rate delta n is greater than n₁And is less than the maximum speed change rate n of the row-cutting operation₂When the diesel engine is in the dynamic process of suddenly accelerating and loading, and still is in the state of cylinder disconnected row work, at this moment, the phenomenon that the diesel engine can not enough admit air appears, and the problem that the dynamic process is not enough to admit air is solved through the intervention of air supplement unit: firstly, opening a main air supply valve to allow high-pressure compressed air to enter a gas collecting cavity, detecting air inlet pressure by a pressure sensor arranged on an air inlet main pipe, judging the air inlet flow at the moment by a speed density method, further determining the actual air inlet flow entering each cylinder, then determining the oil injection quantity required by each cylinder according to the measured real-time rotating speed change rate delta n, determining the required air inlet quantity by a target air-fuel ratio, subtracting the actual air inlet flow of each cylinder to determine the air quantity required to be supplemented, determining the injection pulse width according to the flow characteristic of an air injection valve, then determining the air supply sequence and the air supply timing of each air injection valve in the air supply device, and the stop time of the air supply device, and detecting the top dead center of each cylinder by a position sensor arranged on a crankshaftWhen detecting that a piston in a certain cylinder is firstly positioned a CA degrees before the top dead center of the gas distribution phase when the inlet valve is opened, the inlet valve of the cylinder is opened, the corresponding gas injection valve is opened at the moment, then the gas injection valve is closed according to the preset injection pulse width, whether all the cylinders finish gas injection is judged at the moment, if the gas injection is not finished in any cylinder, the next corresponding cylinder is determined according to the working sequence of the cylinders, when the piston of the cylinder is positioned at the gas distribution phase when the inlet valve is opened, the gas injection valve is correspondingly controlled until all the cylinders finish gas injection, the total gas compensation valve is closed, and the gas compensation device stops working; if the engine still continues to operate, the rotating speed of the crankshaft and the state of the waste gas valve are detected again in real time, and the air supplementing device can be restarted to supplement air for the engine when the air inlet of the engine is insufficient next time, until the engine stops operating, and the air supplementing control flow is finished.

The invention has the advantages that: the air supply device can be matched with a control system, can detect the running state of the engine in real time by collecting pressure and rotating speed signals in the engine cylinder, and further controls the specific running mode of the air supply device according to the running state. Meanwhile, the device adopts the gas collecting cavity to be connected with the gas inlet channel of each cylinder, and can independently control the gas supplement of each cylinder; and the high-pressure injection nozzle is adopted to ensure that the supplementary air is injected to the air inlet valve of each cylinder more quickly and intensively, thereby obviously solving the problems of insufficient air intake of each cylinder of the engine, combustion deterioration and the like caused by the reduction of air flow in the dynamic process when the low-load cylinder of the high-power V-shaped diesel engine is in row-breaking work.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a diagram of the position relationship between the gas collecting chamber and one of the cylinders;

FIG. 3 is a cross-sectional view of the high pressure nozzle;

FIG. 4 is a gas circuit diagram during cylinder bank-off operation;

FIG. 5 is a control flow chart of the operation of the air make-up device in cooperation with a sequential supercharged diesel engine.

Detailed Description

The invention will now be described in more detail by way of example with reference to the accompanying drawings in which:

with reference to fig. 1-5, fig. 1 is a general view of a sequential supercharged diesel engine with an air make-up device. The basic components of the V-type sequential supercharged diesel engine comprise an A-row cylinder 1(A1, A2, A3, A4, A5 and A6), an A-row air inlet manifold 4, a basic turbocharger 3 and an A-row exhaust manifold 2 on the side of the A-row cylinder of the engine; the cylinder side of the bank B comprises an air valve 5, a bank B intake manifold 6, a controlled turbocharger 7, an exhaust gas valve 8, a bank B exhaust manifold 9 and a bank B cylinder 10(B1, B2, B3, B4, B5, B6); in addition, the diesel engine also comprises an intercooler 11 connected with the two rows of air inlet manifolds and other parts. The air supply system device comprises a high-pressure compressed air source 12, a main air supply pipe 14, a main air supply valve 15, an air supply intercooler 16, an air collection cavity 17, an air injection valve 18 and a control unit 13.

The basic turbocharger is connected with the cylinder of the A row, and the controlled turbocharger is connected with the cylinder of the B row. The high-pressure compressed air source stores high-pressure air, the high-pressure compressed air source is connected with one end of a main air supply pipe, an intercooler is arranged on the main air supply pipe, the other end of the intercooler is connected with an air collecting cavity, air supply pipes corresponding to the number of cylinders are arranged on the air collecting cavity and are respectively connected with air inlet channels of the cylinders on the row A side of the air collecting cavity, each air supply pipe is provided with an air injection valve, and the air supply sequence and the air supply timing of each cylinder are controlled. In the intake passage, an air supply pipe is installed at a position closer to the intake valve of each cylinder. The tail end of the air supply pipe is provided with a high-pressure nozzle, and a nozzle of the nozzle is aligned with the air inlet valve. The engine is provided with a pressure sensor, a crank angle sensor and a top dead center sensor, and detected related data can be transmitted to the control unit. The control unit can detect the state of the engine and can be connected with each valve in the air supply device to control the specific operation process of the air supply device. The air supplementing device can detect the real-time running state of the engine through all sensors arranged on the engine, and when the low-load exhaust interruption work of a high-power V-shaped diesel engine, once the load of the engine is suddenly increased, air can be timely supplemented to the cylinder on the working side, so that the combustion deterioration in the transient process is avoided. Meanwhile, the design of the high-pressure nozzle can quickly and intensively spray air to the air inlet valve of each cylinder, so that the quick response of the air and the air quantity demand are realized.

The device adopts the gas collecting cavity to temporarily store high-pressure air, and the volume of the gas collecting cavity is more than 100 times of single air injection amount, so that the problems of fluctuation of pressure in the gas collecting cavity in the air injection process, and further fluctuation of circulation air supplement amount of each cylinder and interference of each cylinder are avoided. The air supply process is stable, and the air supply processes of the cylinders are not interfered with each other.

On the gas collecting cavity, each gas supplementing pipe 19 is provided with an independent gas injection valve 18, and gas can be supplemented to each cylinder in a timed and quantitative manner according to the working sequence and the gas injection timing of each cylinder. Each air supply pipe 19 on the air collection cavity 17 is bent to be deep into the air inlet channel, the tail end of each air supply pipe 19 is provided with a high-pressure nozzle 20, the inner pipe diameter of the high-pressure nozzle is in smooth transition from large to small, the length of the nozzle is short, the nozzle is close to the air cylinder and is aligned with the air inlet valve, high-pressure air jet flow directly penetrates through a gap between the air inlet valve and the air valve seat to enter the air cylinder, air injection energy loss is low, and quick air supply can be achieved. The device adopts the electronic control unit, according to signals such as diesel engine rotational speed, piston position, exhaust valve state, air intake manifold pressure, judges the running state of engine in real time, control air supplement unit and realize regularly quantitatively carrying out the tonifying qi.

The single-row air supplement device of the high-power V-shaped marine diesel engine is matched with the working process of a sequential supercharged diesel engine, so that air supplement is performed on the device when the air inlet of the engine is insufficient. FIG. 2 is a diagram of the position relationship between the air make-up device and one of the cylinders. The volume of the gas collection cavity 17 is about one hundred times of the air inlet flow of the air supply pipe 19, and when each air supply pipe supplies air, the pressure fluctuation of the gas in the gas collection cavity can be ensured to be not obviously changed, so that the air supply process of the air inlet pipe is not influenced mutually, and the uniformity of air supply is ensured. Each air supply pipe is provided with an air injection valve 18, and each air injection valve can be independently controlled by being connected with a control unit, so that independent air supply of each air cylinder is realized. The air injection pipe is bent to penetrate into the air inlet channel, and the penetrating position of the air injection pipe is close to the position of the air inlet valve of the air cylinder, so that the air injection stroke is short, and the air supplement pressure loss is small. The high-pressure nozzle 20 is arranged at the tail part of the gas injection pipe, the internal cross section of the high-pressure nozzle is shown in figure 3, the internal length of the high-pressure nozzle is shorter, and the internal diameter adopts the design of smooth transition from thick to thin, so that the pressure loss of the injected gas is smaller, the injection speed is higher, the delay is lower, and the injection direction of the nozzle is aligned to the position of the gas inlet valve, thereby ensuring the accuracy of the gas supplementing position.

Fig. 4 is a gas circuit diagram in cylinder bank-off operation. When the engine is in low load operation, the fuel supply of the B-row cylinder is cut off to make the B-row cylinder idle, and simultaneously, the successively supercharged diesel engine does not need a plurality of superchargers under the low load, so that the air valve and the exhaust valve which are connected with the controlled superchargers are closed. The gas circuit is shown in the figure when the engine is in operation.

FIG. 5 is a flow chart of the control of the air supply device. The invention also introduces a single-row air supplement method for the high-power V-shaped marine diesel engine. The specific control flow is as follows: when the low-load cylinder is in the exhaust-blocking operation, a rotating speed sensor arranged on a crankshaft detects the rotating speed of the engine in real time, and sets a target rotating speed change rate n needing air supplement₁When the rotating speed sensor detects that the current rotating speed change rate delta n is greater than n₁And is less than the maximum speed change rate n of the row-cutting operation₂When the engine is in the dynamic process of sudden acceleration loading, the diesel engine is still in the state of cylinder row breaking operation; at the moment, the phenomenon of insufficient air intake can occur to the diesel engine, and the problem of insufficient air intake in the dynamic process is solved by the intervention of an air supply device. First, the main air supply valve is opened to allow high-pressure compressed air to enter the air collection cavity. A pressure sensor mounted on the intake manifold detects the intake pressure, and the intake flow at that time is determined by a velocity density method, thereby determining the actual intake flow into each cylinder. And then determining the required oil injection quantity of each cylinder according to the measured real-time rotating speed change rate delta n, determining the required air inflow according to the target air-fuel ratio, subtracting the actual air inflow of each cylinder, determining the air quantity required to be supplemented, and determining the injection pulse width according to the flow characteristic of the air injection valve. And then, the air replenishing sequence and the air replenishing timing of each air injection valve in the air replenishing device and the time for stopping the air replenishing device need to be determined. Detecting the time when each cylinder reaches the top dead center through a position sensor arranged on a crankshaft, and when detecting that a piston in a certain cylinder is firstly positioned at the opening of an intake valveAnd when the valve timing is a DEG CA before the top dead center of the valve timing, the intake valve of the cylinder is opened, the corresponding gas injection valve is opened at the moment, and then the gas injection valve is closed according to the preset injection pulse width. And judging whether all the cylinders finish air supplement, if the cylinders do not finish air supplement, determining the next corresponding cylinder according to the working sequence of the cylinders, and correspondingly controlling the air injection valve of the cylinder when the piston of the cylinder is in the air distribution phase of opening the air inlet valve. And when the air supply of all the cylinders is finished, the air supply is finished, the main air supply valve is closed, and the air supply device stops working. If the engine still continues to operate, the rotating speed of the crankshaft and the state of the waste gas valve are detected again in real time, and the air supplementing device can be restarted to supplement air for the engine when the air inlet of the engine is insufficient next time, until the engine stops operating, and the air supplementing control flow is finished.

Claims

1. A single-row air supplement method for a high-power V-shaped marine diesel engine is characterized by comprising the following steps: the single-row air supplement device comprises an A-row cylinder, a B-row cylinder, a basic turbocharger, a controlled turbocharger and a high-pressure compressed air source, wherein a turbine of the basic turbocharger is connected with an A-row exhaust manifold, the A-row exhaust manifold is connected with the A-row cylinder, a compressor of the basic turbocharger is connected with an A-row air inlet manifold, the A-row air inlet manifold is connected with an air collecting cavity, the air collecting cavity is connected with the A-row cylinder, the high-pressure compressed air source is connected with a main air supply pipe, the main air supply pipe is connected with an air collecting cavity, a turbine of the controlled turbocharger is connected with a B-row exhaust manifold, the compressor of the controlled turbocharger is connected with a B-row air inlet pipe, the A-row air inlet manifold is communicated with the B-row air inlet manifold, the A-row exhaust manifold is communicated with the B-row air outlet manifold through a communicating pipe, a waste gas valve is arranged on the B-row air outlet manifold between the turbine of the controlled turbocharger and the communicating pipe, and an air valve is arranged on the B-row air inlet manifold, a main air supply valve is arranged on the main air supply pipe, and the waste gas valve, the air valve and the main air supply valve are respectively connected with the control unit;

the gas collecting cavity is connected with a gas supplementing pipe through gas injection valves, the gas supplementing pipe extends into the corresponding row A gas inlet manifold to the front of the gas inlet valve, a high-pressure nozzle is arranged at the end part of the gas supplementing pipe, and all the gas injection valves are respectively connected with a control unit;

the volume of the gas collection cavity is 105 times of the inlet flow of the air supply pipe;

when the low-load cylinder is in the exhaust-blocking operation, a rotating speed sensor arranged on a crankshaft detects the rotating speed of the engine in real time, and sets a target rotating speed change rate n needing air supplement₁When the rotation speed sensor detects that the real-time rotation speed change rate delta n is greater than n₁And is less than the maximum speed change rate n of the row-cutting operation₂When the diesel engine is in the dynamic process of suddenly accelerating and loading, and still is in the state of cylinder disconnected row work, at this moment, the phenomenon that the diesel engine can not enough admit air appears, and the problem that the dynamic process is not enough to admit air is solved through the intervention of air supplement unit: firstly, opening a main air supply valve to allow high-pressure compressed air to enter a gas collecting cavity, detecting air inlet pressure by a pressure sensor arranged on an air inlet main pipe, judging the air inlet flow at the moment by a speed density method, further determining the actual air inlet flow entering each cylinder, then determining the oil injection quantity required by each cylinder according to the measured real-time rotating speed change rate delta n, determining the required air inlet quantity by a target air-fuel ratio, then subtracting the actual air inlet flow of each cylinder to determine the air quantity required to be supplemented, then determining the injection pulse width according to the flow characteristic of an air injection valve, then determining the air supply sequence and the air supply timing of each air injection valve in the air supply device, and the stop time of the air supply device, detecting the time of each cylinder reaching the top dead center by a position sensor arranged on a crankshaft, when detecting that a piston in a certain cylinder is firstly positioned a degree CA before the top dead center of the air distribution phase when an air inlet valve is opened, the air cylinder intake valve is opened, the corresponding air injection valve is opened at the moment, then the air injection valve is closed according to the preset injection pulse width, whether all the air cylinders finish air injection is judged at the moment, if the air cylinders do not finish air injection, the next corresponding air cylinder is determined according to the working sequence of the air cylinders, when the piston of the air cylinder is in the air distribution phase of the opening of the intake valve, the air injection valve is correspondingly controlled until all the air cylinders finish air injection, the total air injection valve is closed, and the air injection device stops working; if the engine still continues to operate, the rotating speed of the crankshaft and the state of the waste gas valve are detected again in real time, and the air supplementing device can be restarted to start the engine when the air inlet of the engine is insufficient next timeAnd (5) supplementing air until the engine stops running, and ending the air supplementing control flow.