JP2000249013A - Fuel supplying device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize the whole of a device, and reduce costs by simplifying a structure of a fuel supplying device. SOLUTION: A device is provided with a fuel passage 23 whose one end is connected to a delivery port of an electrically driven type fuel pump 22 and the other one is closed. An injector 12 and a pressure sensor 26 are connected to the fuel passage 23. An ECU 2 for feedback-controlling an output of the fuel pump 22 is connected to the fuel pump 22 so as to match target fuel pressure corresponding to an operating condition of an engine 1 with real fuel pressure detected by the pressure sensor 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel supply system for supplying fuel to an engine by an injector.

[0002]

2. Description of the Related Art Conventionally, this type of fuel supply apparatus employs a structure in which fuel is supplied from a fuel tank to an injector by a fuel pump, and excess fuel remaining without being used for injection is returned to the fuel tank. I have. More specifically, a fuel pump is provided in the middle of a fuel circulation passage having a fuel tank as a start point and an end point, and a fuel pressure setting regulator is provided downstream of the fuel pump. Are connected.

[0003]

SUMMARY OF THE INVENTION The present inventors have developed a conventional fuel supply apparatus constructed as described above, for example, into a small vehicle such as a motorcycle or a snowmobile, an outboard motor, a small planing boat, or a general-purpose engine. We are thinking about making it compact so that it can be equipped with. However, the conventional fuel supply device has a large area occupied by members such as pipes forming a fuel circulation passage and a regulator for setting a fuel pressure.
There is also a limit to making the entire device compact. It is also required to reduce the size and cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to simplify the structure of a fuel supply device to achieve a further reduction in the size of the entire device and a further reduction in cost.

[0005]

In order to achieve this object, an engine fuel supply device according to the present invention has an injector and a fuel passage having one end connected to a discharge port of an electric fuel pump and the other end closed. Connect the pressure sensor,
The fuel pump is connected to a control device for feedback-controlling the output of the fuel pump so that the target fuel pressure corresponding to the operating state of the engine and the actual fuel pressure detected by the pressure sensor match.

According to the present invention, fuel is pumped into the fuel passage so as to supplement fuel consumed by fuel injection.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Hereinafter, an embodiment of a fuel supply system for a vehicle engine according to the present invention will be described in detail with reference to FIGS.
FIG. 1 is a block diagram showing a fuel supply device for a vehicle engine according to the present invention, FIG. 2 is a graph showing a map for obtaining various set values, FIG. 3 is a graph showing a fuel pressure distribution, and FIG.
Is a graph showing the relationship between fuel pressure and fuel pump power consumption, and FIG. 5 is a flowchart for explaining the operation of the fuel supply device according to the present invention.

In these figures, the reference numeral 1 denotes a scooter engine according to this embodiment. The engine 1 is a two-cycle, single-cylinder electronic control type, and has a structure in which a fuel supply device 3 and an ignition device 4, which will be described later, are controlled by an ECU indicated by reference numeral 2 in FIG.

In FIG. 1, reference numeral 5 denotes a cylinder, 6 denotes a crankcase, 7 denotes a piston, 8 denotes a connecting rod, 9 denotes a crankshaft, and 10 denotes a flywheel magneto. A spark plug 11 and an in-cylinder injector 12 are mounted on the cylinder 5, and an intake pipe 13 is connected to the crankcase 6. A throttle valve 14 is interposed in the intake pipe 13 and an oil supply device 15 is connected.

The oil supply device 15 has a structure in which oil stored in an oil tank indicated by reference numeral 16 in FIG. 1 is supplied to an intake passage by an oil pump 17.
The throttle valve 14 is provided with a throttle valve opening detection sensor (not shown) for detecting the throttle valve opening and sending detection data to the ECU 2.

The crankshaft 9 is connected to the rear wheels via a centrifugal clutch (not shown) and a V-belt type automatic transmission. This power transmission system has the same structure as a conventional scooter. In this embodiment, a crank angle sensor (not shown) that detects rotation of the crank shaft 9 and sends detection data to the ECU 2 is provided in the crank case 6.

As the flywheel magneto 10, a conventionally known flywheel that generates electric power by rotating the crankshaft 9 is used.
Connected to CU 2 and battery 19.

The fuel supply device 3 has a reference numeral 21 in FIG.
The fuel stored in the fuel tank is pumped into the fuel passage 23 by the fuel pump 22, and the fuel is supplied from the injector 12 connected to the downstream side of the fuel pump 22 to the cylinder 5.
It adopts a structure to inject inside.

The fuel passage 23 is formed by one pipe connecting the fuel tank 21 and the injector 12, and the fuel pump 22 is interposed on the way. Fuel pump 2
A filter 24 is interposed between the fuel pump 2 and the fuel tank 21, and two dampers 25 and a pressure sensor 26 are connected between the fuel pump 22 and the injector 12. The fuel device 3 does not have the fuel return passage provided in the conventional device.

The damper 25 is provided to attenuate the pulsation generated in the fuel passage 23, and is provided in the fuel passage 23.
A structure is adopted in which a diaphragm 25a constituting a part of the wall is biased toward the fuel side by a compression coil spring 25b.

The pressure sensor 26 is for detecting the fuel pressure in the fuel passage 23, and is disposed between the two dampers 25, 25. The pressure sensor 26 detects a fuel pressure and outputs detection data to the ECU 2.
To send to.

The fuel pump 22 is an electric positive displacement pump and has a structure in which the ECU 2 controls the output. As the fuel pump 22, for example, a plunger type or a vane type can be used. In order to control the output of the plunger type fuel pump, the frequency and voltage of the power supply are changed. By increasing the frequency and voltage, the discharge amount of the fuel pump increases, and the fuel pressure in the fuel passage 23 increases. By reducing the frequency and voltage, the fuel pressure is reduced.

In order to control the output of the vane type fuel pump, the amount of power supplied (supply voltage, supply current) is changed to increase or decrease the number of revolutions of the vane. By increasing the amount of supplied electric power, the discharge amount of the fuel pump increases, and the fuel passage 2
The fuel pressure in 3 rises. By reducing the amount of power supplied, the fuel pressure is reduced.

When the fuel injection period of the injector 12 is constant, the fuel injection amount increases or decreases as the fuel pressure in the fuel passage 23 changes. When the fuel injection amount is smaller than the discharge amount of the fuel pump 22, the fuel corresponding to the difference flows into the damper 25, and in the opposite case, the fuel corresponding to the difference flows from the damper 25. It is supplied to the injector 12 side.

The ignition device 4 includes the ignition plug 11
And a CDI unit 27 for applying a high voltage to the ignition plug 11 and an ignition coil (not shown). The CDI unit 27 and the ignition coil are controlled by the ECU 2 and apply a high voltage to the ignition plug 11 when an ignition control signal is input.

The ECU 2 controls the ignition timing and the fuel injection timing (the timing at which fuel injection is started) corresponding to the throttle valve opening detected by the throttle valve opening detection sensor and the engine speed detected by the crank angle sensor. ,
The basic fuel injection period (time during which fuel is injected) and the target fuel pressure are read from the map shown in FIG.
The I unit 27 is controlled to be ignited at the ignition timing, and the output of the fuel pump 22 is increased or decreased by feedback control so that the actual pressure in the fuel passage 23 matches the target fuel pressure. 12
Is controlled so that fuel is injected during the fuel injection timing and the basic fuel injection period. This ECU 2 constitutes a control device according to the present invention.

FIG. 2A shows an ignition timing map, FIG. 2B shows a fuel injection timing map, FIG. 2C shows a basic fuel injection period map, and FIG. 2 shows a target fuel pressure map.
(D). The ignition timing map is set such that the ignition timing is advanced as the throttle valve opening is smaller, and the ignition timing is advanced as the engine speed is higher. The fuel injection timing map is set so as to advance as the engine speed increases, and to slightly advance as the throttle valve opening decreases.

In the basic fuel injection period map, the larger the throttle valve opening, the longer the fuel injection period.
The fuel injection period is set to be the longest at the engine rotation speed at which the torque of the engine becomes maximum. The target fuel pressure map records the fuel pressure at which fuel is injected from the injector 12 during the basic fuel injection period by the supply amount required by the engine. You have set.

When the fuel pressure is controlled based on the target fuel pressure map, as shown in FIG.
The lower the load (throttle valve opening) and the engine speed, the lower the load and the higher the load and the engine speed. The power consumption of the fuel pump 22 is
As shown in FIG. 4, it increases as the fuel pressure increases. In the figure, the changes in fuel pressure and power consumption when the output of the fuel pump is made constant (when the voltage (6 V, 8 V, 10 V, 12 V) is made constant) are shown by a two-dot chain line.

Next, the operation of the fuel supply device 3 configured as described above will be described with reference to FIG. 5 together with a more detailed description of the configuration of the ECU 2. During the period from when the cranking is performed for starting the engine to when the engine 1 is stopped, the ECU 2 always detects the engine speed and the throttle valve opening as shown in step S1 of FIG.

In step S2, the ECU 2 reads the ignition timing, fuel injection timing, basic fuel injection period, and target fuel pressure corresponding to the engine speed and the throttle valve opening from the map shown in FIG. Next, the ECU 2
In step S3, the fuel pressure (actual fuel pressure) in the fuel passage 23 is detected, and in step S4, the differential pressure between the actual fuel pressure and the target fuel pressure read from the map is calculated.

After obtaining the differential pressure, the ECU 2 increases or decreases the output of the fuel pump 22 by feedback control so that the differential pressure becomes zero in step S5. If the target fuel pressure is higher than the actual fuel pressure, the fuel pump 22
Is increased, and vice versa.

After the output control of the fuel pump 22 is performed,
In step S5, the ECU 2 sends an injector control signal to the injector 12 to inject fuel for the basic fuel injection period at the fuel injection timing read from the map. At this time, the ECU 2 sends an ignition control signal to the CDI unit 27 so that the ignition is performed at the ignition timing read from the map.

After controlling the fuel supply system and the ignition system in this way, the ECU 2 determines in step S7 whether or not the engine 1 is stopped. This determination is made based on the engine speed. When it is determined that the engine 1 is stopped, all the controls are stopped, and when the engine 1 is operating, the process returns to step S1 to repeat the above-described control.

Therefore, according to the fuel supply device 3 configured as described above, the fuel is pumped into the fuel passage 23 by the fuel pump 22 so as to replenish the fuel consumed by the fuel injection. Compared to the device,
A passage for circulating the fuel in the fuel supply system and a regulator for setting the fuel pressure are not required.

[0031]

As described above, according to the first aspect of the present invention, the passage for circulating the fuel in the fuel supply system and the regulator for setting the fuel pressure are not required. The structure can be simplified, and downsizing and further cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a fuel supply device for a vehicle engine according to the present invention.

FIG. 2 is a graph showing a map for obtaining various set values.

FIG. 3 is a graph showing a fuel pressure distribution.

FIG. 4 is a graph showing a relationship between fuel pressure and fuel pump power consumption.

FIG. 5 is a flowchart for explaining the operation of the fuel supply device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... ECU, 12 ... Injector, 21
... Fuel tank, 22 ... Fuel pump, 23 ... Fuel passage, 2
6 ... Pressure sensor.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hidehiro Nishimura 2500 Shinkai, Iwata-shi, Shizuoka Yamaha Motor F-term (reference) 3G301 HA04 HA26 JA00 LB06 LC10 MA11 MA18 NC02 ND01 PA11Z PA17Z PB08A PB08Z

Claims (1)

[Claims] 1. An electric fuel pump, wherein one end of a fuel passage connected to a discharge port of the electric fuel pump is closed at the other end, an injector and a pressure sensor are connected to the fuel passage, and the fuel pump corresponds to an operating state of an engine. A fuel supply device for a vehicle engine, wherein a control device that performs feedback control of an output of a fuel pump is connected so that a target fuel pressure matches an actual fuel pressure detected by the pressure sensor.