KR20000045744A - Mass air flow meter for measuring countercurrent adopted in suction system of automotive vehicle - Google Patents

Abstract

PURPOSE: A mass air flow meter for measuring a countercurrent adopted in a suction system of automotive vehicle is provided to achieve an improved engine performance and reduce exhaust gas while permitting the amount of fuel injection to be controlled by precisely measuring the amount of air flowing into the combustion chamber of the engine. CONSTITUTION: A mass air flow(MAF) meter(10) arranged intermediate an air duct(4) connecting an air cleaner and a throttle body, the MAF meter(10) comprising a Pitot pipe(20) arranged in the rear of a heating resistor(12) in such a manner that the entrance of the pipe(20) is directed toward the throttle body, and a total pressure sensor(21) and a static pressure sensor(22) arranged at an end of the Pitot pipe(20), the sensors(21, 22) being circuit-connected to an ECM(14) so as to sense the total pressure state and static pressure state of the air flowing into the Pitot pipe(20) and apply a signal representing such state to the ECM(14).

Description

MP Meter for Backflow Measurement of Automobile Intake Machine

The present invention relates to a mass air flow (MAF) meter (Meter) for the reverse flow measurement of the intake of automobiles, and more particularly, to accurately measure the air flow flowing from the outside to the combustion chamber of the engine to effectively operate the engine The present invention relates to a MAF meter for reverse flow measurement of an automobile intake machine, which, in turn, improves engine performance.

In general, automobiles generate power by burning a mixture of fuel and air.

That is, the fuel stored in the fuel tank of the vehicle and passed through various fuel supply devices is mixed with the air introduced from the outside to generate a mixer, and the mixer is injected into the cylinder of the engine and the engine is sucked, compressed, It works by repeating the explosion and exhaust stroke, and thus the car gets power.

At this time, the engine requires approximately 1% of fuel and air close to 10 m ³ , which is introduced from the outside of the vehicle as described above, and this air contains a lot of dust and various foreign substances. Will be.

Thus, an air cleaner for removing sand dust and various foreign matters from the air introduced from the outside of the vehicle is provided. The air passing through the air cleaner flows to the combustion chamber of the engine via the throttle body.

However, as described above, fuel and air are mixed at a constant ratio for the operation of the engine, sucked into the cylinder, and ignited by the high-voltage electricity.

As such, the ratio of fuel and air mixing is about 15 g for burning 1 g of gasoline engine, and about 8500 cc of air is required for 1 cc of gasoline. In this case, the amount of air required to completely burn 1 g of gasoline is referred to as a theoretical performance ratio.

Therefore, the fuel supply device of an automobile must always supply gasoline and air in a state close to the theoretical performance ratio to the engine while driving. In the past, gasoline was supplied to the intake manifold in the same way as the wick, kerosene lamp wick, but this method can only supply a certain amount of gasoline and can not respond to changes in the rotation of the engine is the carburetor adopted here.

However, the mixer supplied to the gasoline engine requires precise control in order to simultaneously satisfy the purification of the exhaust gas, the reduction of fuel consumption, and the improvement of the output. Conventionally, a two-valve or variable venturi vaporizer has been used to form a more suitable mixer, but it is impossible to make a mixer that perfectly adapts to all operating conditions.

Therefore, a fuel injection device has been developed that can theoretically supply the mixer required by the engine to near perfect condition.

This fuel injection device electrically detects the intake air amount and injects the fuel according to the operating conditions of the engine, so that the ECM is used for these controls, which is called an electronically controlled fuel injection device.

The electronically controlled fuel injection device basically makes fuel at a high pressure by a fuel pump and feeds it to the injector, and at the same time maintains a constant pressure at a constant pressure, so as to inject the fuel system to increase the precision and the opening degree of the throttle valve or the air valve. System to supply air to the cylinder according to the intake air flow rate detection device, throttle body, surge tank, etc., intake air volume, engine rotation speed, throttle valve opening, etc. are detected and sent as ECM to the water temperature It can be divided into control cylinder which controls fuel injection timing and injection amount by signals from various sensors such as air intake temperature.

The present invention relates to an intake air amount detection device which detects the intake air amount in such an electronically controlled fuel injection device to precisely control the fuel injection amount. Among them, a heating resistor is installed in the flow of the intake air and energized, and changes according to the air flow rate. The present invention relates to a heat-type air flow meter, that is, a MAF meter 10, in which a current value flowing through a resistor is changed so as to maintain a constant temperature of the heating resistor.

The MAF meter 10 is located at an intermediate side of the air duct 4 through which air passing through the air cleaner 2 flows to the throttle body 3 side, as shown in FIGS. 1 to 3. The screen 11 is provided in a mesh type so that air can flow uniformly over the entire area of the air duct 4, the heat generating resistor 12 in contact with the air passing through the screen 11, and the heat generating resistor It consists of an animometer (13) for energizing the current (12) so that it is always kept isothermal, which is connected to the ECM (14). Referring to the operation relationship of the MAF meter 10 made as follows.

First, when the outside air is introduced by the negative pressure of the engine 1 and passes through the air duct 4 to flow to the throttle body 3 side while sand dust and various foreign matters are removed through the air cleaner 2. The air passes evenly over the entire area of the air duct 4 while passing through the screen 11 installed in the mesh side on the middle side of the air duct 4.

At this time, the heat generating resistor 12 installed on the rear side of the screen 11 is continuously energized from the animometer 13 so as to always maintain a constant temperature, at this time the temperature is approximately 100 ℃, a thin film It is made of a shape.

Therefore, when the air that has passed evenly through the screen 11 of the air duct 4 hits the heat generating resistor 12 and continuously passes and flows to the throttle body 3 side, the heat generating resistor 12 is air. The friction with the causes heat loss.

In this case, the animometer 13 continuously energizes the current by the heat lost by the heat generating resistor 12 to maintain the heat generating resistor 12 in an isothermal state. In this case, the animometer 13 The ECM 14 reads the energized current value and measures the intake air amount.

That is, when the intake flow rate of the air increases, the friction with the heat generating resistor 12 increases, so that the heat loss of the heat generating resistor 12 increases, so that the animometer 13 allows the heat generating resistor 12 to conduct electricity. As the current value increases, the ECM 14 can know that the amount of intake air increases.

Therefore, the ECM 14 that detects the intake air amount by the above method controls the fuel system in accordance with the intake air amount to control the fuel injection amount in accordance with the theoretical performance ratio, thereby effectively controlling the engine operation, and ultimately the engine performance. It will be improved.

However, in the MAF meter having the above structure, when the air passing through the air cleaner rubs against the heat generating resistor through the screen, and flows to the throttle body side, the air flow rate is measured by this friction. When the air flowing toward the throttle body flows back and causes friction with the heating resistor again, the intake air amount that becomes a negative value due to the heat loss of the heating resistor due to the friction is detected as a positive value and thus the fuel injection amount By increasing the value, there is a problem such that complete combustion is not achieved due to the enrichment of the fuel, resulting in deterioration of engine performance and excessive emission of harmless exhaust gas.

Accordingly, the present invention has been made to solve the above problems, by measuring the intake air flow flowing from the outside to the combustion chamber of the engine more precisely to effectively control the operation of the engine, thereby improving the engine performance It is an object of the present invention to provide a MAF meter for the reverse flow measurement of automobile intake machines.

The present invention for achieving the above object is a MAF meter installed in the middle side of the air duct connecting the air cleaner and the throttle body to measure the intake flow rate of the vehicle, it is installed on the rear side of the heating resistor of the MAF meter, A pitot tube whose entrance is directed toward the throttle body; And a total pressure sensor and a static pressure sensor installed at an end of the pitot tube and connected to the ECM to detect the total pressure and the static pressure state of air flowing into the pitot tube and apply the signal to the ECM. .

1 is a perspective view showing an intake tube of a conventional vehicle;

2 is a view schematically showing the positional relationship of the MAF meter for the reverse flow measurement of the intake machine applied to a conventional vehicle,

3 is a schematic view of the MAF meter in FIG.

4 schematically shows a MAF meter according to the invention;

Explanation of symbols on the main parts of the drawings

2: air cleaner 3: throttle body

10: MAF Meter 11: Screen

12: heat generating resistor 13: animometer

14 ECM 20 pitot tube

21: total pressure sensor 22: static pressure sensor

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The same parts as in the prior art are denoted by the same reference numerals, and repeated description thereof will be omitted.

4 is a view schematically showing a MAF meter according to the present invention.

As shown, in the MAF meter 10 installed at the middle side of the air duct 4 connecting the air cleaner 2 and the throttle body 3, the rear side of the heat generating resistor 12 of the MAF meter 10 is provided. A pitot tube 20 is provided with the inlet facing toward the throttle body 3.

The pitot pipe 20 is bent horizontally by a predetermined length from the inlet side and made vertically, and a total pressure sensor 21 and a static pressure sensor 22 are installed at the end thereof, and the sensors 21 and 22 are The circuit is connected to the ECM 14.

Therefore, an air duct connecting the air cleaner 2 and the throttle body 3 so that air introduced from the outside by the negative pressure of the engine 1 flows through the air cleaner 2 toward the throttle body 3 side ( When passing through the MAF meter 10 installed on the intermediate side of 4), the air flows to the throttle body 3 side through the screen 11 and the heating resistor 12 of the MAF meter 10, The ECM 14 detects the intake air flow due to the heat loss of the heat generating resistor 12 due to friction between the heat generating resistors 12.

At this time, when the air flowing toward the throttle body 3 flows back to the heat generating resistor 12 side of the MAF meter 10, the air of the pitot tube 20 installed on the rear side of the heat generating resistor 12. Flowing through the inlet, at this time, the total pressure sensor 21 and the static pressure sensor 22 installed at one end of the pitot pipe 20 transmits this signal to the ECM 14, the ECM 14 is the total pressure sensor ( 21) and the dynamic pressure is measured and read based on the total pressure and the static pressure received from the static pressure sensor 22, thereby detecting that the air has flowed back.

In other words, the total pressure is obtained by the sum of the static pressure, the dynamic pressure, and the frictional resistance value, and the frictional resistance value can be neglected when the cross-sectional area of the pitot tube is small, so that the total pressure can be obtained by the sum of the static pressure and the dynamic pressure.

Therefore, since the total pressure and the static pressure are sensed by the amount of air flowing into the pitot pipe 20, the dynamic pressure can be obtained.

At this time, the dynamic pressure can be obtained by 0.5 × air density × flow rate ² , the air density is obtained by the temperature sensor mounted on the intake pipe, it is possible to obtain the flow rate flowing into the pitot pipe 20, Accordingly, the ECM 14 can read the above values comprehensively to determine the amount of backflow.

Therefore, when the ECM 14 determines the reverse flow amount in this manner, the current value passed through the animometer 13 according to the heat loss of the heat generating resistor 12 due to the reverse flow of air is equal to (+) of the intake air flow rate. It recognizes it as (-) value instead of) value and controls the appropriate fuel injection amount.

When the MAF meter having the above configuration is applied to the automobile intake machine, the intake flow rate flowing into the combustion chamber of the vehicle is more precisely measured and the fuel injection amount is controlled, thereby forming a mixer suitable for the theoretical performance ratio and eventually burning it. In addition to improving the engine performance, the effect of reducing the exhaust gas is also increased accordingly.

Claims (1)

In order to precisely measure the intake air flow flowing into the combustion chamber of the engine 1, it is installed in the middle of the air duct 4 connecting the air cleaner 2 and the throttle body 3, and the air duct 4 is A screen 11 for allowing air to pass through evenly over the entire surface, a heat generating resistor 12 provided on the rear side of the screen 11 and friction with intake, and the heat generating resistor 12 maintain an isothermal state. An animometer 13 which energizes a current so as to be connected to the animometer 13, and an ECM which reads the intake flow rate by the current value which the animometer 13 energizes the heat generating resistor 12. In the MAF meter 10 of the automobile intake machine composed of (14), A pitot tube (20) installed at the rear side of the heat generating resistor (12) and whose inlet is directed toward the throttle body (3); A total pressure sensor installed at one side of the pitot pipe 20 and connected to the ECM 14 to detect the total pressure and the static pressure of the air flowing into the pitot pipe 20 and apply the signal to the ECM 14. (21) and the positive pressure sensor (22); MAF meter for the reverse flow measurement of the car intake machine, comprising a.