JPS6321827B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electronically controlled carburetor, and particularly to an electronically controlled carburetor that can obtain a proper air-fuel ratio over the entire operating range of an engine.

(Prior Art) It is well known that a carburetor for an internal combustion engine is generally configured to utilize airflow from a bench lily and to inject and atomize fuel using the negative pressure.
What is required in this case, for example, is that the fuel and air are mixed uniformly and the injected fuel is atomized, whether the air flow is small at low speed loads or the air flow is large at high speed loads. There must be. However, in order to promote atomization and mix uniformly with air, a certain level of air flow rate is required. For this reason, a variable bench lily type carburetor is employed in order to maintain the air flow rate approximately constant when the amount of intake air changes depending on the operating state.

A conventional variable bench lily type carburetor will be explained with reference to FIG. In FIG. 1, reference numeral 1 denotes a suction pipe, which is connected to an air cleaner (not shown), and into which suction air is introduced as indicated by the arrow shown. 2 is an air control valve, and a throttle valve 3
The bench lily is provided on the upstream side of the bench, and moves up and down like a piston as shown by the arrow in the figure, forming a bench lily. Reference numeral 4 is a float chamber in which a float 5 is provided, which floats in accordance with the vertical movement of the fuel surface 6. Reference numeral 7 denotes a float arm, which is attached integrally with the float 5 and moves in accordance with the vertical movement of the float, so that the needle valve 8 moves up and down, and an appropriate amount of fuel is injected each time. Reference numeral 9 denotes a jet needle, which is integrally formed on the lower surface of the air control valve 2 described above, and changes the opening area of the fuel discharge port 10 according to the vertical movement of the air control valve 2, and dispenses fuel according to the amount of intake air. It is configured to inject the air to achieve an appropriate air-fuel ratio. Although it is not clearly shown in the drawing, a piston spring is inserted into the air control valve 2, and normally the rising force due to the differential pressure between the negative pressure of the bench lily and the air control valve internal pressure and the air control valve It is fixed at a position where its own weight and the downward force from the piston spring are balanced.

(Problems to be Solved by the Invention) In the conventional carburetor having the above configuration, the air control valve 2 and the jet needle 9
are integrated, and the vertical movement of the air control valve is based on the mechanical conditions described above, so engine conditions and atmospheric conditions are not taken into account, and therefore the fuel is adjusted according to the situation. Not only is it impossible to change the flow rate trend, but
It has the disadvantage that it is not possible to control the air-fuel ratio with high flow accuracy due to frictional forces in the mechanical sliding parts.

The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide an electronically controlled carburetor that can obtain an appropriate fuel flow rate trend over the entire operating range.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention uses engine speed, suction pipe internal pressure, and slot valve opening as standards, and by appropriately combining these, the fuel discharge means for pre-calculating the suction pressure near the outlet; means for calculating a correction amount for the suction pressure near the fuel discharge port based on engine conditions and atmospheric conditions; It consisted of means for calculating the required suction pressure near the outlet, and a motor for determining the difference between the required suction pressure and the actual measurement value and operating the air control valve so as to reduce this difference to zero.

(Function) Therefore, in the present invention, the required suction pressure is determined in advance by taking various conditions into consideration, and the motor is operated so as to make the difference between the required suction pressure and the actual measurement value zero.

(Example) An example will be described below with reference to the drawings. Second
3 is a control block diagram, FIG. 4 is a flowchart for arithmetic processing, and FIG. 5 is a block diagram of an embodiment of an electronically controlled vaporizer according to the present invention. It is a block diagram of an Example.
In FIG. 2, the numbers 1 to 10 in the figure are the first
Corresponds to the diagram. Reference numeral 11 denotes a drive device, for example, a servo motor or a stepping motor, which moves the air control valve 2 up and down so as to correct the vent pressure at the fuel discharge port 10 position and the required set pressure. The required set pressure at this time is not simply the pressure from the flow rate, but also takes into account the fuel correction amount. Here, the control conditions include rotational speed, intake pipe internal pressure, throttle valve opening, engine temperature (or cooling water temperature), intake air temperature,
Atmospheric pressure, fuel discharge port pressure, air control valve position, etc. are input, but from among these, rotation speed, suction pipe internal pressure, and throttle valve opening are referenced and these are combined appropriately to obtain the required fuel discharge port. Calculate the pressure and control the position of the air control valve to achieve that value. Then, increase corrections such as acceleration correction, warm-up correction, intake temperature, atmospheric pressure correction, etc. are performed by shifting the required set pressure higher or lower (by changing the position of the air control valve 2) to increase or decrease the pre-calculated required setting pressure. Achieve weight gain and weight loss. It should be noted that the air control valve 2 is finely moved up and down according to the pitch of the screw shaft 12. Or, by a linear motor etc.
It can be moved up and down directly without a reduction mechanism. 13 is an air bypass, and 14 is an air bypass adjustment screw, which finely adjusts the amount of air when the engine is idling and improves the ability to detect the position of the throttle valve, which will be described later. That is,
Since the position (opening degree) of the throttle valve 3 is detected by a potentiometer (not shown) provided on the throttle valve, in order to improve the detection ability, it is necessary to detect the position (opening degree) of the throttle valve 3 at a low opening degree. It is necessary to reduce the rate of change in air amount with respect to change in opening degree. Bypass air is an effective method for this purpose.

An outline of the operation of the electronically controlled carburetor having the above configuration will be explained next.

First, when the engine is idling, the throttle valve 3 is almost closed, so the amount of intake air is small. Therefore, in order to bring the bench pressure to the required set pressure in accordance with the amount of air taken in during idling, the air control valve 2 is lowered to increase the flow rate. The amount of air in this case is finely adjusted by the air bypass 13. In this state, when the throttle valve 3 is gradually opened, the amount of intake air gradually increases, the flow velocity of the vent lily increases, and the negative pressure increases. Therefore, the difference between this negative pressure and the required set pressure is corrected and controlled by opening the air control valve 2 by the servo motor 11, but the position of the air control valve 2 at this time depends on the fuel control conditions and engine conditions. The position takes into account corrections due to atmospheric conditions, etc.
That is, the positional "deviation" due to the above correction is added to the position of the control valve 2, which is uniquely determined only by the pressure at the fuel discharge port position. This means that the position also includes the fuel control portion.

This will be explained in more detail with reference to the control block diagram in FIG. In the figure, the mechanical movement from the accelerator is directly transmitted to the throttle valve via a wire, and the mechanical movement from the accelerator is transmitted directly to the throttle valve via a
is introduced into the electronically controlled carburetor along with a control signal to the air control valve from the air control valve. The air-fuel mixture from the electronically controlled carburetor is then sucked into the engine, and torque is generated by engine operation. In this case, operations including fuel control are performed based on the calculation output from the MPU. Information such as air control valve position, throttle opening, and fuel discharge port pressure is input from the electronically controlled carburetor to the MPU.
Further, engine parameters such as rotation speed, engine temperature (or cooling water temperature), intake pipe internal pressure, throttle valve opening, etc. are input from the engine, as well as atmospheric conditions such as temperature and atmospheric pressure. Among these, the required fuel discharge port pressure is calculated by appropriately combining the rotational speed, suction pipe internal pressure, and throttle valve opening.
Alternatively, as described above, the required fuel discharge port pressure is calculated from the air flow sensor output value, and a correction amount is added thereto.

The calculation program will be explained with reference to the flowchart shown in FIG. Figure a shows the main routine. In the figure, Step 41 is for branching to the motor drive side and the condition calculation side, and takes 10 msec.
This is done on the basis of (This value of 10 msec is provisional and is normally set to 10 to 100 ms in consideration of matching with the engine.) Therefore, if it is within the above 10 msec, the process moves to Step 42, where the operation mode determination process is performed. . This is to determine whether the engine is stopped, idling, accelerating, decelerating, cranking, etc. In Step 43, the intake air amount is measured. That is, for example, the intake air amount is calculated using known measured values such as throttle opening, engine speed, intake pipe internal pressure, and air control valve position, or directly measured using an air flow sensor.
In Step 44, based on the intake air amount measured in Step 43, basic fuel discharge port pressure calculation processing is performed to obtain the required mixture ratio.
In Step 45, a fuel discharge port pressure correction process is performed in accordance with the operating mode, and further correction processes such as an increase in acceleration amount and an increase in warm air amount are performed. In Step 46, fuel discharge port pressure correction processing is performed in accordance with the environment, and this serves as data for determining the air control valve position.

On the other hand, in Step 41, when it reaches 10msec
The process moves to Step 47, where the deviation between the required set pressure for the fuel discharge port and the actual measurement value is calculated. If there is a deviation, the output train to the motor to be driven is calculated in Step 48 so that the deviation becomes zero, and the next In Step 49, the output to the motor is derived.
That is, the air control valve position is corrected every 10 msec. In this case, the air control valve position is determined by the required set pressure and is modified by taking fuel control or other conditions into consideration.

FIG. 4b is a subroutine, Step 50
In this step, sampling processing of analog data such as operating conditions is performed.

The above subroutine interrupts the process shown in FIG. 4A every time the ignition signal is received.

FIG. 5 is a block diagram of another embodiment of an electronically controlled vaporizer according to the present invention. Numbers 1 to 10 in the diagram
and 12 to 14 correspond to FIG. 1
5 is a drive motor, such as a servo motor or a stepping motor. 16 is a motor shaft, and 17 is a gear. 18 is a reduction gear that engages with the gear 17, thereby rotating the screw shaft 12 and moving the air control valve 2 up and down. Other than the above-mentioned driving means, the structure and operation are exactly the same as those shown in the second figure, and the calculation program is also the same.

〔Effect of the invention〕

As explained above, according to the present invention, the rotation speed,
The fuel discharge port pressure is calculated based on the suction pipe internal pressure and the throttle valve opening, and the air control valve position is determined to achieve the calculated pressure. With this configuration, it is possible to provide an electronically controlled carburetor that not only provides low fuel consumption but also provides an ideal air-fuel ratio.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional variable bench lily type carburetor, Fig. 2 is a block diagram of an embodiment of an electronically controlled carburetor according to the present invention, Fig. 3 is a control block diagram, and Fig. 4 is a block diagram for arithmetic processing. , in which a shows the main routine, b shows the subroutine,
FIG. 5 is a block diagram of another embodiment of the electronically controlled vaporizer according to the present invention. 1...Intake pipe, 2...Air control valve,
3... Throttle valve, 4... Float chamber, 5... Float, 6... Oil level, 7... Float arm, 8...
Needle valve, 9... Jet needle, 10
...Fuel discharge port, 11...Servo motor, 12...Screw shaft, 13...Air bypass, 14...Air bypass adjustment screw, 15...Servo motor, 1
6...Motor shaft, 17...Gear, 18...Reduction gear.

Claims (1)

[Claims] 1. In an electronically controlled carburetor that operates an air control valve located upstream of a throttle valve in accordance with the amount of intake air of the engine to maintain the intake pipe vent pressure at a predetermined value and control the mixture concentration, the engine speed, A means for pre-calculating the suction pressure near the fuel discharge port provided in the variable bench lily by appropriately combining the suction pipe internal pressure and the throttle valve opening as a reference, and based on the engine conditions and atmospheric conditions. means for calculating a correction amount for the suction pressure in the vicinity of the fuel discharge port; means for calculating a required suction pressure in the vicinity of the fuel discharge port based on each of the calculated values; An electronically controlled carburetor characterized by comprising: a motor that calculates a difference and operates an air control valve to reduce this difference to zero.