CN101598091B - Stabilized voltage fuel injection system - Google Patents

Abstract

The invention discloses a stabilized fuel injection system. The fuel injection system mainly includes a high-pressure oil pump, a pressure accumulator, a fuel injector, a flow sensor, a servo motor, a motor drive module, and an electric control unit. The input end of the electric control unit is connected to The flow sensor is used to process the signal of the flow sensor and compare it with the flow set value as the reference amount for feedback control. If the difference between the two exceeds the set control amount, the electronic control unit will issue an adjustment control command, which is driven by the motor. The module adjusts the rotation speed of the servo motor to control the deviation of the fuel flow of the injector within the set range. The pressure stabilizing fuel injection system of the invention has the characteristics of accurate fuel flow control, convenience, fast response speed and the like.

Description

A stabilized fuel injection system

technical field

The invention belongs to the technical field of engines, in particular to a pressure-stabilizing fuel injection system for engines.

Background technique

The Stirling engine is an external combustion closed cycle reciprocating piston heat engine, which is different from the internal combustion engine which relies on the combustion of fuel inside the engine to obtain power. The Stirling engine uses gas as the working medium. The fuel burns continuously in the combustion chamber outside the cylinder, and is transmitted to the working medium through the heater. The working medium does not directly participate in the combustion and is not replaced. The heater expands the gas when it is heated, and compresses it when it is cooled. Power is generated to drive the piston, and the expanded gas is cooled in the cold air chamber, and this cycle is repeated. Since the external combustion engine avoids the knocking work problem of the traditional internal combustion engine, it realizes high efficiency, low noise, low pollution and low operating cost. The external combustion engine can burn various combustible gases, such as: natural gas, biogas, petroleum gas, hydrogen, coal gas, etc., can also burn liquid fuels such as diesel oil and liquefied petroleum gas, can also burn wood, and utilize solar energy. As long as the thermal cavity reaches 700°C, the equipment can work and run, and the lower the ambient temperature, the stronger the working ability. The biggest advantage of the external combustion engine is that the output and efficiency are not affected by the altitude, which is very suitable for use in high altitude areas. However, the Stirling engine still has many problems to be solved, such as high manufacturing cost, difficult working fluid sealing technology, problems with the reliability and life of the seal, complicated power regulation control system, and relatively heavy machine.

In a Stirling engine that burns liquid fuels such as diesel, changing the operating parameters of the Stirling engine, such as the cycle pressure of the working medium or the fuel flow, can change the output power of the Stirling engine. There are two main methods of changing the fuel flow at present:

1) The high-pressure oil pump supplies fuel with a fixed flow rate to the pressure accumulator at a fixed speed. There is an overflow valve connected to the fuel tank in the pressure accumulator. By controlling the opening of the overflow valve, the excess fuel overflows back to the fuel tank to control the accumulation. The main disadvantages are: the oil supply of the oil pump is constant, but when the pressure of the accumulator exceeds the set value, part of the high-pressure fuel will be released through the overflow valve, wasting the energy of the oil pump;

2) The high-pressure oil pump supplies oil to the accumulator at a certain fixed speed. It adjusts the displacement of the oil pump rack in the oil volume control device through the setting value of the control system to control the oil volume pumped into the accumulator by the oil pump, but Its disadvantages are: the adjustment accuracy of the rack is insufficient, and it is difficult to accurately control the amount of fuel entering the accumulator, resulting in excessive fluctuations in fuel pressure in the accumulator and unstable output power of the engine.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art, and provide a fuel injection system with constant pressure to change the fuel supply by controlling the speed of the high-pressure oil pump. The fuel injection system has the characteristics of convenient, accurate and fast response to fuel quantity control .

The technical solution of the present invention is: a stabilized fuel injection system, including a high-pressure oil pump, a pressure accumulator, and a fuel injector connected in series in the oil circuit, and the system also includes:

A flow sensor, which is connected in series in the oil circuit connecting the pressure accumulator and the fuel injector to measure the fuel flow of the fuel injector;

A servo motor, which is connected to the high-pressure oil pump to drive the high-pressure oil pump to work;

A motor drive module, which controls the speed of the servo motor through a servo driver;

An electronic control unit, the input of which is connected to the flow sensor to obtain the flow signal of the flow sensor, and the output of which is connected to the motor drive module to output the motor control command; the electronic control unit processes the flow signal and uses it as a reference for feedback control If the difference between the two exceeds the set control value, the electronic control unit will issue an adjustment control command to adjust the servo motor speed through the motor drive module to limit the deviation of the fuel flow of the injector. within the set range.

The electric control unit is also connected with a motor speed control knob, and the speed control knob provides a motor speed setting signal to the electric control unit as a flow setting value compared with the flow signal of the flow sensor, so that the injection of the high-pressure oil pump The oil quantity is continuously adjustable.

An oil supply regulating valve is installed on the high pressure oil pump, and the oil supply regulating valve controls the amount of low pressure oil entering the oil pump when the high pressure oil pump is started through the electronic control unit.

A pressure transmitter is installed on the pressure accumulator, and the pressure transmitter is connected with the electronic control unit to monitor the fuel pressure and pressure fluctuations in the pressure accumulator as a parameter for judging the working condition of the system.

In the present invention, the high-pressure oil pump is driven by a servo motor, and the actual fuel injection quantity of the fuel injector is detected by a flow sensor, and the flow fluctuation of the fuel oil is controlled within a certain range by controlling the speed of the servo motor through the electronic control unit, and the flow control of the fuel oil is accurate. , convenient, fast response, so that the output power control of the Stirling engine is very stable; the fuel supply regulating valve installed on the high pressure oil pump can control the low level signal of the electronic control unit through the fuel supply regulation drive module when the system starts Open the bottom first, and the bypass passage in the valve is connected to bypass the oil passage to reduce the starting resistance torque and ensure the smooth start of the high-pressure oil pump. Under the control of the level signal, the working current is provided to the oil supply regulating valve, the bypass passage in the valve is closed and the oil passage leading to the working chamber of the oil pump plunger is opened, and the pump oil starts to supply oil to the pressure accumulator.

Description of drawings

Fig. 1 is a block diagram of the fuel injection control system of the present invention.

Detailed ways

Taking the Stirling engine as an example, as shown in Figure 1, the figure shows a stabilized fuel injection system installed in the Stirling engine. The stabilized fuel injection control system mainly includes a A high-pressure oil pump 1 is used to pressurize the fuel in the low-pressure oil circuit D to provide high-pressure fuel. The high-pressure oil pump 1 is driven by a servo motor 5, and a pressure accumulator 2 is connected to the high-pressure oil pump 1 to store the fuel pumped out by the high-pressure oil pump. , and the fuel injector 3 connected to the output oil passage of the pressure accumulator 2 to inject the high-pressure fuel in the pressure accumulator 2 into the combustion chamber R of the Stirling engine, the fuel injector 3 is an open type fuel injection A flow sensor 4 for measuring the fuel flow of the fuel injector is connected in series in the oil passage connecting the accumulator 2 and the fuel injector 3, and the flow sensing signal of the flow sensor 4 is connected to an electronic control unit 10 superior. The input end of the electronic control unit 10 is connected to the flow sensor 4 to compare the signal of the flow sensor 4 with the flow setting value used as a reference amount for feedback control after processing, and the volume of the plunger working chamber of the high-pressure oil pump 1 remains unchanged. And under the premise of constant fuel inlet pressure, if the speed increases, the fuel supplied to the accumulator per unit time increases, the fuel pressure in the pressure accumulator rises, and the fuel injection quantity increases; when the speed decreases, the fuel supplied to the accumulator per unit time increases. The fuel supply decreases, the fuel pressure in the accumulator decreases, and the fuel injection volume decreases; when the amount of fuel flowing into the accumulator is equal to the amount of oil flowing out of the accumulator, the pressure in the accumulator remains stable. If the difference between the two exceeds the set control amount, the electronic control unit 10 sends an adjustment control command, and the servo driver 6 of the servo motor 5 is controlled by the motor drive module 11 to adjust the speed of the servo motor 5, and the deviation of the flow rate is limited to the set value. within the specified range.

The motor speed control knob 8 is also connected to the electric control unit 10, and the motor speed control knob 8 provides a motor speed setting signal to the electric control unit 10, so that the working speed of the high-pressure oil pump can be continuously adjusted.

An oil supply regulating valve 13 is also installed on the high pressure oil pump 1, and the oil supply regulating valve 13 can control the amount of low-pressure oil that enters the high pressure oil pump 1 when starting. When the oil supply adjustment drive module 12 receives the low-level signal from the electronic control unit 10, the oil supply adjustment valve 13 is in a normally open state due to no current passing through, and the low-pressure oil in the high-pressure oil pump 1 passes through the side of the oil supply adjustment valve 13. The high pressure oil pump 1 idles without supplying oil to the pressure accumulator, so that the driving torque required by the high pressure oil pump 1 is minimized. Therefore, when the system is started, the oil supply regulating valve 13 is not energized first, so as to reduce the starting resistance torque and ensure the smooth start of the high pressure oil pump 1 . When the high-pressure oil pump 1 stabilizes at the operating speed, the oil supply regulation drive module 12 provides operating current to the oil supply regulation valve 13 under the control of the high-level signal of the electronic control unit 10, and the bypass passage in the valve is closed to the high-pressure oil pump. 1 The oil circuit of the plunger working chamber is opened, and the pump oil starts to supply oil to the pressure accumulator.

A pressure transmitter 13 is installed on the pressure accumulator 2, and the pressure transmitter 13 is connected with the electronic control unit 10 to monitor the fuel pressure and pressure fluctuations in the pressure accumulator 2 as a parameter for judging the working condition of the system.

The present invention is not limited to the above embodiments, and the pressure stabilizing fuel injection system can be applied not only to Stirling engines, but also to all engines using open fuel injectors.

Claims (3)

1. A stabilized fuel injection system, comprising a high-pressure oil pump, a pressure accumulator and a fuel injector connected in series in the oil circuit, characterized in that the system also includes: A flow sensor, which is connected in series in the oil circuit connecting the pressure accumulator and the fuel injector to measure the fuel flow of the fuel injector; A servo motor, which is connected to the high-pressure oil pump to drive the high-pressure oil pump to work; A motor drive module, which controls the speed of the servo motor through a servo driver; An electronic control unit, the input of which is connected to the flow sensor to obtain the flow signal of the flow sensor, and the output of which is connected to the motor drive module to output the motor control command; the electronic control unit processes the flow signal and uses it as a reference for feedback control If the difference between the two exceeds the set control value, the electronic control unit will issue an adjustment control command to adjust the servo motor speed through the motor drive module to limit the deviation of the fuel flow of the injector. within the set limits; A pressure transmitter, the pressure transmitter is installed on the pressure accumulator and connected to the electronic control unit to monitor the fuel pressure and pressure fluctuations in the pressure accumulator as a parameter for judging the working status of the system. 2. The stabilized fuel injection system according to claim 1, characterized in that, the electronic control unit is also connected with a motor speed control knob, and the speed control knob provides a motor speed setting signal to the electronic control unit as The flow setting value compared with the flow signal of the flow sensor makes the injection quantity of the high-pressure oil pump continuously adjustable. 3. The stabilized fuel injection system according to claim 1, characterized in that, the high-pressure oil pump is equipped with an oil supply regulating valve, and the oil supply regulating valve controls the high-pressure oil pump to enter the oil pump when starting up through the electronic control unit. low pressure oil volume.

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