Measuring and testing – Test stand – For engine
Reexamination Certificate
1999-09-20
2001-10-30
McCall, Eric S. (Department: 2855)
Measuring and testing
Test stand
For engine
C073S117020, C073S114220
Reexamination Certificate
active
06308558
ABSTRACT:
According to the preamble of claim
1
, the invention relates to a method for checking the effect of swirl ducts in multicylinder internal combustion engines, especially engines with direct injection, in which a cylinder subjected to a vacuum, especially a simultaneous cylinder with a swirl measuring device, is associated on the combustion chamber side with a cylinder head with at least one swirl duct per cylinder, and a swirl number is assigned to each of the swirl flows per cylinder generated as a function of throughput by means of the swirl ducts and by an intake valve whose stroke can be varied. A swirl number determined by a formula from these cylinder-related swirl numbers is related to an engine-specific swirl tolerance band.
It is known that in cylinder heads that are produced by casting, including the swirl ducts, relatively slight deviations in the position of the core for shaping the swirl ducts result in extremely poor swirl results, with the disadvantage of a not insignificant number of cylinder head rejects. To check the quality and/or effect of the cast swirl ducts, the method according to the species is used as is known for example from DE 26 13 275 C. This method, used in particular for the development of a swirl duct, is used to determine an optimum swirl flow in the cylinder of different diaphragms movably associated with the swirl ducts, for individual swirl production in order eventually to be able to determine the geometry of the swirl duct. This document also teaches the usability of the method for a standard cylinder head with swirl ducts.
Another swirl measuring method using the device is known from DE 195 35 486 C; the intensity of the respective swirl is determined using a novel form of measurement technology. A cylinder head for a diesel engine is known from DE 40 18 065 A, said head having two intake passages located diametrically with respect to each cylinder, one of which passages being a swirl duct to produce swirl and the other also having a controllable throttle device. In addition, a cylinder head with two intake passages per cylinder is known from DE 39 36 263 A, with both a swirl duct and a filling channel being controlled by a common rotary valve. In addition, the other means known in engines with direct injection for influencing swirl, such as variable valve control, valve cutout, or a flap control provided in the intake, are too cumbersome for swirl correction on an individual cylinder basis.
The goal of the invention, when using the method according to the invention for swirl ducts with a fixed path, to develop measures for subsequent swirl correction for the individual cylinders.
This goal is achieved by claim
1
by virtue of the fact that depending on a swirl number outside the swirl tolerance band, the corresponding swirl channel in the cylinder head is subsequently made smaller or larger in cross section in a channel section.
Specifically, this is accomplished in a first embodiment of the invention in an advantageously simple fashion by the fact that when the swirl is too low according to a swirl number that falls below the swirl tolerance band, a bushing with a through flow cross section that is reduced relative to the other swirl duct cross section is provided subsequently to increase the swirl in the swirl ducts of the cylinder head, or/and a valve seat ring with a smaller inside diameter is used.
In a second embodiment according to the invention, it is proposed that when the swirl is too great according to a swirl number that exceeds the swirl tolerance band, to reduce the swirl, a constriction defined in the swirl duct is enlarged accordingly in the through flow cross section, or/and the inside diameter of a valve seat ring and/or the exit angle of the valve seat ring are increased, with the exit angle of the valve seat ring pointing in the swirl direction and possibly making a transition to a frustroconical depression in the bottom of the cylinder head on the combustion chamber side.
With the measures according to the invention outlined above, the swirl flow is corrected on a individual cylinder basis in simple fashion and therefore the number of cylinder head rejects is reduced and, in an engine with direct injection, combustion is made uniform in all of the cylinders, with the advantage of reduced fuel consumption and improved exhaust quality.
An especially advantageous re-working solution is achieved with a swirl duct associated with each cylinder in the cylinder head, with a duct path in the cylinder head that is essentially parallel to the cylinder axis. A channel section formed in this channel in simple fashion allows either a subsequent enlargement of the cross section or a subsequent use of a bushing with a reduced through flow cross section in an advantageous manner. In a channel path parallel to the cylinder axis, a duct portion can advantageously be provided there according to the invention by machining using chip removal, simply either for a subsequent increase in the cross section or to use a bushing with a reduced through flow cross section.
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patent: 5870993 (1999-02-01), Stellet et al.
patent: 6041753 (2000-03-01), Lin et al.
patent: 26 13 275 (1977-10-01), None
patent: 39 36 263 (1990-05-01), None
patent: 195 35 486 (1996-12-01), None
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SAE Technical Paper Series, Feb. 25, 1991, pp. 1-12 entitled Effect of Intake Port Flow Pattern on the In-Cylinder Tumbling Air Flow in Multi-Valve SI Engines by S. Omori et al.
Dworschak Johannes
Niedereder Werner
Ratzberger Reinhard
Bayerische Motoren Werke Aktiengesellschaft
Crowell & Moring LLP
McCall Eric S.
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