JPS5918261A - Fuel supplying device - Google Patents

Abstract

PURPOSE:To prevent the generation of fuel vapor bubble in a fuel pipeline by a method wherein a means, discharging or introducing the fuel in a manifold in accordance with an operating condition, is provided in the device, distributing and supplying the metered fuel into each cylinders through the manifold. CONSTITUTION:The fuel supplying device meters the fuel from a fuel pump 1 in a fuel metering unit 2, equipped with a metering valve 23 and a pressure regulator 24, thereafter, supplies the fuel into No.1-No.4 cylinders through the branched pipes 32, 33 of a distributing unit 3 and orifices 34a, 34b, 35a, 35b. In this case, a valve 36, having the driving source of a solenoid controlled by a micro-computer, is provided slidably. When the valve 36 is pulled down to a position B, the branched pipes 38, 39 are opened to supply the fuel into No.1- No.4 cylinders through the orifices 34c, 34d, 35c, 35d, however, in case the whole of the flow amount is reduced, the valve is located at the position A to empty the fuel in the branched pipes 38, 39 and prevent the generation of the vapor bubble.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system, and particularly to a fuel supply system suitable for use in a multi-cylinder internal combustion engine.

In general, fuel supply systems for multi-cylinder internal combustion engines are divided into two methods: one method is to independently meter a solenoid valve provided for each cylinder by ON-OFF control, and the other method is to separate the sound of fuel from a single calculation valve and distribute it to each cylinder. There is a method (for example, JP-A-55-29096, 1% JP-A-52-11812). Both of these methods tend to generate fuel vapor bubbles in the fuel piping, and to completely prevent this, the fuel pressure in the piping must be reduced to 2.0 Kg/tyn'.
It is necessary to maintain the above amount, and the driving horsepower of the fuel pump is larger than that of the carburetor, which has the disadvantage of increasing fuel consumption. In addition, the former independent metering method requires the provision of high-precision solenoid valves to equalize the fuel # in each cylinder.
It has the disadvantage of high cost.

The object of the present invention is to provide a fuel distribution method that can prevent the generation of fuel vapor bubbles in the fuel pipe, reduce the fuel pressure f: about 0.6 Kg/cm, and reduce the driving horsepower of the fuel pump. The purpose is to provide a supply device.

The gist of the present invention is as follows. In other words, a known example of a conventional distribution system, JP-A-55-29096, branches downstream of a constant pressure valve, and a fixed orifice is provided at the tip of the branch pipe to separate the flow, so that the fuel flow rate during idle link operation is reduced. It was found that the flow rate and pressure in the branch pipe become small in a small area, making it difficult to prevent the generation of steam bubbles. In the above-mentioned known example, a second constant pressure valve and a second branch pipe are added and the second constant pressure valve is operated in a region where the flow rate is large, and a part of the fuel is diverted through the second branch pipe. Some methods have also been disclosed for relatively suppressing the drop in flow rate and pressure in the first branch pipe, but when the engine is stopped and the flow rate is zero, the pressure in the pipe becomes atmospheric pressure, and steam bubbles It is not possible to completely prevent the occurrence. Formation of vapor bubbles 1.1: Part of the fuel in the pipe is forced out of the orifice and enters the intake pipe, making the air-fuel mixture in the intake pipe too rich, making it even more difficult to restart the engine.

A common method to avoid this is to install a check valve at the tip of the fixed orifice to completely prevent pressure drop and fuel leakage. However, if a check valve is provided at the tip to maintain the pressure inside the branch pipe at a high pressure, the flow division ratio will be affected by the flow characteristics of the check valve. It is necessary to install a flow divider to equalize the flow divided into each cylinder. In addition, since fuel remains in the branch pipe when the engine is stopped, in order to prevent the generation of steam bubbles, 2. It is necessary to maintain a pressure of approximately oKp/(7)2, and the check valve is required to have a high degree of accuracy to prevent leakage.

The above two known examples? In the latter method, which maintains the fuel pressure at high pressure during the fm experiment, the fuel pressure is kept at 0.6
It was found that it is difficult to stop the generation of fuel vapor bubbles in the branch pipe when the temperature drops to about K9/cm". Due to the generation of vapor bubbles, the fuel in the branch pipe becomes empty, and when restarting, While fuel fills the branch pipe,
Fuel is not supplied to the engine and restarting the engine is significantly inhibited. This problem can be resolved by reducing the diameter of the branch pipe, but reducing the diameter of the branch pipe increases the pressure loss, and it is difficult to cover the maximum flow rate at a pressure of 0.6 Kf/cm". For this reason, a method of providing a second branch pipe is considered, but as many check valves as there are branch pipes are required, and the fuel in the second branch pipe remains, the fuel in the entire branch pipe is The amount does not decrease and therefore
It turned out that the problem could essentially be resolved.

In the former known example having the second branch pipe, the above-mentioned problems are the same, and since there is no check valve, the fuel pressure is low, and the generation of fuel vapor bubbles is also severe. However, during the course of the experiment, it was found that the above problem could be resolved by adjusting the amount of fuel in the branch pipe in advance when the engine is stopped. However, if the fuel is empty, it will take time to restart as mentioned above. This problem can be avoided by providing a means for completely filling the branch pipe with fuel when starting the engine.

Therefore, the present invention provides a means for sucking fuel into a branch pipe that divides fuel into each cylinder, and a means for filling the branch pipe with fuel, thereby preventing the generation of fuel vapor bubbles in the fuel pipe and reducing the fuel pressure. The aim is to reduce the fuel pump's drive horsepower to approximately 0.6Ky/cm".

Examples of the present invention will be described below.

FIG. 1 shows an embodiment of the invention.

The fuel supply device includes a fuel pump section l, a fuel metering section 2,
It is composed of a flow dividing section 3 and an air measuring section 4.

The fuel pump section 1 is as follows. That is, centrifugal,
The pressure is increased to about 0.6 K9 by a vortex-type fuel pump 10, and the fuel is pumped to a pressure regulator 12 via a check valve 11. Lower chamber 13 of regulator 12
The pressure is maintained constant, and excess fuel returns to the fuel tank 15 through the return pipe 14. The steam bubbles are discharged through return pipe 14.

Further, the fuel metering section 2 is as follows. That is, a metering valve 23 is provided at the other end of a pipe 21 connected to the lower chamber 13 , and the downstream side of the metering valve 23 is connected to a lower chamber 25 of a pressure regulator 24 via the tube 21 . The upper chamber of the pressure regulator 24 is connected to a pipe 27 via a pipe 26 . By the operation of this pressure regulator 24, the metering valve 2
The pressure difference before and after 3 is 0. It is maintained at about I Ky/cm'.

The metering valve 23 is a normal needle valve or slit valve, and the flow path area changes depending on the stroke. That is, the stroke controls the fuel flow rate through the tube 22. The stroke is determined by the microcomputer 270 using a proportional solenoid connected to the metering valve 23 or a mechanical quantity conversion means 28 such as a pulse motor.
Controlled by command. Signals such as the rotational speed of the engine and the opening degree of the accelerator pedal can be input to the microcomputer 27. As a result, an appropriate amount of fuel flows through the pipe 22 depending on the state of the engine. The cutting valve 23 may be an intermittent electromagnetic solenoid valve. In this case, @ is controlled by the valve opening time width.

The flow rate varies from 1 to 50 t/h, which is the total flow rate of the engine. The volume valve 23 may be a volumetric means such as a positive displacement pump.

Further, the flow dividing portion 3t is as follows. That is, a pipe 31 is connected to the pressure regulator 24 . pipe 3J
A branch pipe 32 and a branch pipe 33 are branched from the pipe. Branch pipe 3
At the tip of 2, an orifice 34b and 34a1 are attached.

A refits 35a and 35b are attached to the tip of the branch pipe 33. Orifices 34a, 34b.

The diameters of 35a and 35b are all equal, about 0.5 mm, and the diameters of Ino 1. The fuel flowing out from the orifice is supplied to the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder, respectively. The flow rate of the pipe 31 is equally distributed to each cylinder by the orifice. The pipe 31 is provided with a knob 36, and when the flow rate of the pipe 31 increases, branch pipes 38, 39
Open. The electromagnetic solenoid 37f is driven by the microcomputer 27 to pull down the valve 36. During this lowering operation, the lower part of the valve 36, indicated by A,
Fuel fills branch pipe 38,39. When the valve 36 is pulled down to position B, the branch pipes 38, 39 open and the orifices 34c, 34d, 35c open.

35d, fuel is supplied to the first cylinder, second cylinder, third cylinder, and fourth cylinder, respectively. In this state, when the overall flow rate becomes small, the valve 36 returns to the position shown in FIG. Therefore, the branch pipes 38 and 39 are free of fuel, and the generation of fuel vapor bubbles when the engine is stopped can be prevented.

Further, the air measuring section 4 is as follows. That is, the throttle valve 41 provided in the intake pipe 43 of the engine is rotated by the servo motor 42. A signal from an air flow rate t44 attached to a part of the intake pipe 43 is input to the microcomputer 27, and the servo motor 42 is driven so that the air flow rate reaches a set value, thereby opening and closing the throttle valve 41.

FIG. 2 shows a detailed view of the flow dividing section 3.

In the figure, tube 31 is connected to flow dividers 59, 60, 61. Now, when the valve 53 of the flow divider 59 is pulled down, the branch pipes 32 and 33 are filled with fuel, and the valve 53 is
Since it descends to the position of 53a, branch pipes 32, 33 and
The pipe 31 is connected, and the fuel in the pipe 31 flows through the orifice 34a.
, 34b, etc., and are equally distributed to each cylinder. Here, other orifices are omitted. When the flow rate increases, the valve 54 of the flow divider 6() is pulled down, and the branch pipe 38°39
Fill with fuel, and fully supply fuel to each cylinder from the orifice at the tip. When the flow rate increases further, the valve 55 of the flow divider 61 is pulled down, and after the branch pipes 5, 52 are filled with fuel, fuel is supplied to each cylinder from the orifice at the tip. In this way, as the fuel rlLt increases, the entire opening area of the orifice at the tip increases, so the pressure in the tube 31 increases to 0.5 K as shown in FIG.
f/cm”. In Figure 3, Q+
The flow divider 60 operates at Q2, and the flow divider 61 operates at Q2. When the flow rate decreases, first the valve 55 is pulled up to empty the fuel in the branch pipes 51, 52, then the valve 54 is pulled up to empty the fuel in the branch pipes 38, 39, and finally when the engine is stopped Pulp 53 is pulled up and branch pipe 32.3
Starting from the amount of fuel in 3. Therefore, when the engine stops,
There is no fuel in the branch pipe, and even if it is heated by the heat of the engine, steam ff9. does not occur. Valve 53, 54.55
is controlled by the microcomputer 27 by a solenoid 56°57.58. Q+ in Figure 3
, when valve 54.55 operates at point Q20, some hysteresis characteristics are provided, and valve 54.55 is turned ON.
.

Prevents OFF operation. As can be seen from the system of FIG. 1, even if the valves 54, 55 operate and the pressure in the pipe 31 changes, the differential pressure across the metering valve 23 is maintained constant by the operation of the pressure regulator 24. Fuel flow rate does not change.

Next, the operation of the pressure regulator 24 will be explained.

Now, when the pressure P1 in the pipe 22 increases, the entire diaphragm 70 of the pressure regulator 24 in FIG. 1 is pushed up. Therefore, the pressure P1 in the tube 22 decreases, and the pressure I in the tube 22 is maintained constant. FIG. 4 shows the relationship between flow rate Q and pressure P. Here, the pressure P2 of the pipe 31 is relative to the flow IQ,
As shown in Figure 4, the diamond 7 ram 70
The flow rate of fuel through the lower gap 71 decreases and the same flow rate is handled, so the gap 71 increases. In other words, it is necessary to pull the diaphragm 70 higher. That is, P is raised to P1m. However, in the present invention, as shown in FIG. 3, the increase in the pressure P in the pipe 31 is suppressed, so the change in P 1 m is small.

In the configuration shown in FIG. 1, when the metering valve 23 is cut off, the pipe 22
The flow rate becomes zero, and the gap 71 becomes zero. The pressure Q, 6Ky/(7)2 of the tube 26 is applied to the diaphragm 70 from above, and the pressure of 0. I Kq / Qn
” is acting from one side.

When the fuel in the pipe 22 leaks from the gap 71, the downward force increases, causing the fuel to leak from the gap 71! To prevent. When the engine is stopped, the valve 53.54°55
The outlet of pipe 31 is cut off. Therefore, the gap 71
If there is a leak, the pressure between the tubes 22 and 31 is maintained at an intermediate value. In this way, even if the pressure regulator 24 leaks to some extent, fuel will not leak and be supplied to the engine.

Next, the treatment of steam bubbles in the piping will be explained.

In FIG. 1, tube 21. The steam bubbles generated in the pipe 26 can be easily discharged to the top of the pressure regulator 12 by providing the pressure regulator 12 at the top. Through the return pipe 14 at the same time as the fuel pump lO is started,
It can be easily drained and there are no problems caused by fuel vapor bubbles.

Steam bubbles in the pipe 22 are blocked by the metering valve 23 and cannot be discharged to the regulator 12 side.

The vapor bubbles in the tube 22 are discharged to the component pressure regulator 24 shown in FIG. The steam bubbles discharged to the pressure regulator 24 side accumulate in a chamber to the left of the diaphragm 70 of the regulator 24. In addition, the steam bubbles in the pipe 31 are also caused by the diaphragm 7.
It accumulates in the chamber to the left of 0. This steam? The IU f passes through the valve 53, the branch pipe 32, and is discharged from the orifice 34a. During operation, the valve 53 is sucked to the left by the solenoid 56, and the branch pipe 32 is filled with the solvent in part A, and the branch pipe 32 is connected to 'W31, and the flow rate of the pipe 31 is controlled through the orifice 348. and distribute it to each cylinder.

When the engine is stopped, the fuel in the branch pipe 32 is A as described above.
be taken back to the department. Although the fuel in this part A boils when heated, it cannot be completely discharged from the orifice 34a because the diameter of the dividing pipe is as small as about 2m+n.

Also, since it is not exposed to air, evaporation loss is minimal. In the configuration shown in FIG. 5, it is the tube 31 that generates the most significant steam bubbles. This is discharged to the outside through the bleed hole 100.

Another embodiment of the flow divider is shown in FIG.

In the figure, a lever 201 is attached to a throttle valve 41 that throttles the amount of air in an engine 200.

When this throttle valve 41 rotates, the lever 201 moves and the seventh
As shown, the members 202 and 203 are moved via springs. With the claw of the member 202, the valve stem 20 of the valve 53 is
4, and with the tab of member 203, close the valve 54.
Hook the pawl on the valve stem 205. In this way, depending on the opening degree of the throttle valve 41, first the valve 53 is operated, and then the valve 54 is operated. In this case, the solenoids 57, 58 shown in FIG. 2 are not required. FIG. 8 is a modification of FIG. 6, in which a diaphragm 255 is used instead of the piston valve.
256 is used to take in and take out fuel.

Suction negative pressure is applied from the pipe 257 to the diaphragms 255 and 256. When the suction negative pressure decreases, diaphragm 2
55 and 256 move to the right and valves 258 and 259 open one after another. FIG. 9 shows another embodiment, in which when the fuel flow rate through the pipe 31 is small, the pressure regulator 301 is operated and the fuel is divided into each cylinder via the branch pipes 32 and 33. When the flow rate increases, the pressure regulator 302 is also activated and full fuel is also supplied from the branch pipe 38,39. Here, when the engine is stopped, the solenoid 304 is driven, the diaphragm 305 is pulled down, and the fuel in the branch pipes 32, 33, 38, 39 is emptied. At the time of starting, the diaphragm 305 is pulled up and the branch pipes 32, 33° 38.39 are filled with fuel.

Next, atomization of fuel will be explained.

In the configuration shown in Fig. 6, the branch pipe 32°38.33
．． The flow rate of fuel flowing out from the orifice 348 at the tip of the fuel cell 39 is generally low. Also, the orifice 34a is connected to the intake pipe 4.
3, fuel is sucked out by suction negative pressure,
The pressure in the branch pipe 32 tends to be below atmospheric pressure. In order to avoid this, as shown in FIG.
is an auxiliary air passage 310 provided in a part of the intake pipe 43
It is provided upstream of the orifice 311 of. In this way, the outlet of the orifice chair 34a is maintained at atmospheric pressure.

The fuel flowing out from the orifice 34a is atomized by the auxiliary air in the passage 310 and supplied to the engine. When the throttle valve 41 is fully open and the pressure in the intake pipe 43 is close to atmospheric pressure,
A compressor is provided upstream of the auxiliary air passage 310 to reduce the air flow rate through the orifice 311 and promote atomization. Further, as shown in FIG. 11, a cylinder 312 is provided in the intake pipe 43, and this is made to resonate with a piezoelectric element 313 of 20 to 30 kJ (Z vibrator) to guide the fuel in the branch pipe 32 to the inner surface of the cylinder 312. This can promote atomization of fuel.

Therefore, according to this embodiment, in the distribution type fuel supply device, the fuel pressure is reduced to 0.6 Kq/by supplying and withdrawing fuel in the branch pipe according to the operating state of the engine.
(1) Even if it is as low as about 2, problems due to the generation of fuel vapor bubbles can be avoided, so the drive horsepower of the fuel pump can be reduced, and the engine IP cost can be reduced.

As explained above, according to the present invention, the generation of fuel vapor bubbles in the fuel piping is completely prevented and the fuel pressure is reduced to 0.6/c.
m'', thereby reducing the driving horsepower of the fuel pump.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a detailed configuration diagram of a flow dividing section, Fig. 3 is a pressure characteristic diagram of fuel flow rate, Fig. 4 is a diagram showing the relationship between pressure and flow rate, and Fig. 5 is a diagram showing the relationship between pressure and flow rate. Figure vJ shunt configuration diagram,
Figure 6 is a diagram showing another embodiment of the flow divider, Figure 7 is an explanatory diagram of the operation of the valve stem, Figure 8 is a 71 scrap diagram of a modification of Figure 6, and Figure 9 is another example of the flow divider. Figures illustrating an embodiment, Figure io is a configuration diagram of an orifice, and Figure 11 is a diagram showing an imager provided in an intake pipe. ■...Fuel pump section, 2...Fuel metering section, 3...
Diversion part, 33 Author iM Shizuka 7M ＼M

Claims (1)

[Claims] 1. A fuel supply device in which fuel metered by one fuel metering flat membrane is divided into a plurality of fuels through all branch pipes, and each of the divided fuels is distributed and supplied to a plurality of corresponding cylinders, A fuel supply device characterized in that it is provided with means for introducing and removing fuel in the branch pipe according to operating conditions.