Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
2001-07-09
2002-08-06
Lo, Weilun (Department: 3748)
Internal-combustion engines
Charge forming device
With fuel pump
C123S090310, C123S090600
Reexamination Certificate
active
06427669
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention pertains to drives for pump-nozzle injection elements or injection pumps for internal combustion engines.
Drives of the general type in question for pump-nozzle injection elements of internal combustion engines with a camshaft, driven by a crankshaft via a form-locking traction means, e.g., a timing belt or chain, so that the torque angles change in synchrony for the actuation of the pump-nozzle injection elements, are known.
The optimum nominal output of an engine is achieved when the fuel is delivered at the fastest rate at a certain angle before top dead center of the compression stroke; the optimum maximum torque, however, is achieved at a different maximum fuel feed rate angle (FIG.
3
). The reason for this is that the course of the combustion process is determined qualitatively for the most part by the point in time at which the largest specific amount of fuel is injected with optimum atomization.
It is already known that an angle-adjusting device can be installed in the drive between the crankshaft and the camshaft to set the area of maximum stroke velocity of the cams to the optimum angular position. This is precisely what the injection timing mechanisms already used in injection pumps and pump-nozzle units do. In the case of drives without an injection timing mechanism, the angle before top dead center of the compression stroke at which the area of the cam which produces the maximum stroke velocity is set represents a compromise, so that both a high torque and a high nominal output are achieved.
In drives of this type with a form-locking traction means, the traction means, such as a timing belt or chain, stretches to a certain extent, depending on the load and the length of time it has been in service.
As a result, the angular relationship between the crankshaft and the camshaft set at the factory shifts in the direction of a greater angular distance before top dead center. This usually leads to a loss of power in the operating range where nominal output is obtained.
Under the influence of the torque which actuates the fuel feed element, the camshaft of the drive also twists, and thus, the farther the cam is from the drive plane of the camshaft, the greater the elastic twist of the camshaft. The angle of this rotation also leads to an increase in the angle before TDC in comparison with the angle between the crankshaft and the camshaft set at the factory. This leads to the previously described loss of power.
SUMMARY OF THE INVENTION
The invention is based on the task of designing a drive of the general type in question without an injection timing mechanism for pump-nozzle injection elements and injection pumps in such a way that long-term changes in the traction means and in the load-dependent twist of the camshaft have hardly any effect on the nominal output.
This is achieved according to the invention in that the torque angle or range of torque angles before TDC of the cams at which they produce the maximum feed rate deviates from the optimum angle before TDC. The amount by which this angle deviates from the optimum angle is equal to or less than the angular error resulting from the increase in the length of the traction means. By the use of a design such as this, it is possible. to keep both the nominal output and also the maximum torque at nearly constant values.
The use of an injection timing mechanism or the periodic readjustment of the angle between the camshaft and the crankshaft during the operating life of the drive can therefore be eliminated.
In a similar way, it is also possible according to the invention to compensate for the effects of torque on the actuation of the fuel feed element, i.e., the effects which result from the elastic twisting of the camshaft of the drive. Details on this aspect are provided in the proper context of the following description.
REFERENCES:
patent: 5159904 (1992-11-01), Ingold
patent: 5307781 (1994-05-01), Nakada et al.
patent: 5823168 (1998-10-01), Otoh et al.
patent: 5899181 (1999-05-01), Kurata et al.
patent: 579 557 (1933-06-01), None
patent: 70 12 067 (1970-10-01), None
patent: 31 46 875 (1982-08-01), None
patent: 38 23 107 (1989-03-01), None
patent: 39 28 104 (1990-03-01), None
patent: 40 26 013 (1992-02-01), None
patent: 689 01 803 (1993-01-01), None
patent: 42 32 783 (1994-01-01), None
patent: 0 011 611 (1980-05-01), None
patent: 2 090 911 (1982-07-01), None
Lo Weilun
Volkswagen Aktiengesellschaft
LandOfFree
Actuators for pump-nozzle-injection elements or injection... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Actuators for pump-nozzle-injection elements or injection..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Actuators for pump-nozzle-injection elements or injection... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2880407