Fuel-metering system for internal combustion engines

Details Fuel-metering system for internal combustion engines Fuel-metering system for internal combustion engines

1989-10-04

1991-06-04

Argenbright, Tony M.

Internal-combustion engines

Engine speed regulator

Responsive to deceleration mode

123493, F02D 4112, F02D 4134, F02M 5100

Patent

active

050204955

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to a fuel-metering system for internal combustion engines in which the quantity of fuel to be metered per ignition interval is fixed in dependence on operating characteristics of the engine such as speed, air intake quantity and temperature. In this system, the fuel metering is blocked or at least reduced at the beginning of overrun and released again at the end of overrun.


BACKGROUND OF THE INVENTION

Such a fuel-metering system is known from U.S. Pat. No. 4,242,991. In the case of this fuel-metering system, during the overrun operation of the engine, that is, when the speed with closed throttle flap exceeds a certain value, the fuel feed is entirely switched off or at least strongly throttled. After the end of the overrun operation, in particular after the end of a lengthy overrun operation, the engine along with the intake pipe may have cooled to such an extent that part of the fuel condenses on the inside surface of the intake pipe and cylinder. This part of the fuel is lost from the ignition mixture, which thus becomes too lean. As the consequence of this, the engine does not run smoothly, the speed dips excessively or the engine cuts out. In addition, hydrocarbon emission peaks occur in the exhaust gas.
In order to achieve the rapid build-up of a fuel film on the wall after overrun cutoff without impairing the quantitative balance of the metered fuel on the one hand and of the mixture fed to the cylinder for combustion on the other hand, with overrun cutoff the steady fuel quantity metered from the metering system, corresponding to the operating point of the engine, is enriched by a predetermined extra quantity of fuel. The extra quantity may in this case be constant over a certain number of ignition pulses and metering pulses coupled therewith, or may be varied with each metering pulse.
Even with variation of the extra quantity with each metering pulse, the quantity of fuel metered as a whole can always only be an inadequate compromise due to the complex interrelationships of the necessary additional wall-film quantity and the associated operating collective prehistory of the engine. The extra quantity may be too great or too small. This has the corresponding effects. An excessively rich mixture leads to carbon monoxide exhaust gas peaks, a still too lean mixture leads to hydrocarbon emission peaks and to cutting-out of the engine.


SUMMARY OF THE INVENTION

The fuel-metering system according to the invention has in comparison the advantage that, due to the provision of the lambda probe, the additional enrichment of the metered fuel quantity is interrupted when it is reliably established that there is "rich mixture". An excessively lean or rich mixture can thus be avoided to a great extent.
In the case of internal combustion engines with lambda control system (U.S. Pat. No. 4,492,204), the lambda probe already in this control system may advantageously be used. In this case, the probe signal of the lambda probe can be evaluated for the enrichment cutoff even in states of lambda control prohibition, and thus with open control loop.


BRIEF DESCRIPTION OF THE DRAWING

The invention is explained in more detail in the following description with reference to an exemplary embodiment represented in the drawing. The drawing shows a block circuit diagram of a fuel-metering system.


DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

In the drawing, 10 denotes a pulse generator, which triggers the ignition signals for the engine and the pulse repetition frequency of which is dependent on the speed of the engine. The pulses are fed to a fuel-metering unit 11, which consists of a metering-time setting device 12 and electromagnetic injection valves, which are combined in a block 13. The electromagnetic injection valves effect an injection of fuel into an air-intake pipe of the engine during the metering time predetermined by the metering-time setting device.
The metering-time setting device 12 has a first timing element 14 and a second timing element 15. Th

REFERENCES:
patent: 4242991 (1981-01-01), Scherenberg et al.
patent: 4250853 (1981-02-01), Harada et al.
patent: 4327682 (1982-05-01), Harada
patent: 4414941 (1983-11-01), Nakanishi
patent: 4434769 (1984-03-01), Otobe et al.
patent: 4452212 (1984-06-01), Takase
patent: 4492204 (1985-01-01), Bertsch et al.
patent: 4527521 (1985-07-01), Hasegawa et al.
patent: 4697559 (1987-10-01), Suzuki et al.

Affiliated with

Also associated with

Rating

Fuel-metering system for internal combustion engines does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Fuel-metering system for internal combustion engines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel-metering system for internal combustion engines will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1019783