V8 Engine Intake Valve Lift Control for Rotational Smoothness
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Solution Overview
Problem
Internal combustion engines with eight cylinders in a V-type configuration face challenges in reducing rotational non-uniformity, particularly at idling and lower part-load ranges, leading to rough running and increased fuel consumption and pollutant emissions.
Innovation Solution
The solution involves adjusting the intake valve lifts of each cylinder bank to equalize the specific work of individual cylinders, with gas exchange inlet valves having a larger lift after a 90° crank angle, and using intermediate elements like rocker arms or hydraulic lash adjusters to achieve this, thereby reducing rotational non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional valve lift settings are used in all cylinders, then the engine structure remains simple, but rotational non-uniformity increases leading to rough running at idle and part-load
Solution Approach 1:
The patent applies different valve lift settings to specific cylinders based on their position in the cylinder bank. Cylinders are divided into groups (e.g., first and fourth cylinders in bank 1, second and third cylinders in bank 2) with distinct lift profiles. This local differentiation equalizes the specific work of individual cylinders, reducing rotational non-uniformity and improving running smoothness without requiring complex system-wide control mechanisms.
Solution Approach 2:
The valve train system is segmented into multiple independent control paths, with each cylinder or cylinder group having its own valve lift control mechanism. This segmentation allows independent optimization of each cylinder's gas exchange process, enabling precise control over the specific work of individual cylinders while maintaining overall system simplicity through modular implementation.
2Ease of operation
If application-related measures are used to reduce rotational non-uniformity, then running smoothness improves, but efficiency decreases with higher fuel consumption and CO2 emissions
Solution Approach 1:
The patent changes the valve lift parameter specifically for certain cylinders to equalize their specific work output. By adjusting the intake and/or exhaust valve lift in selected cylinders (e.g., cylinders 1 and 4 in bank 1, cylinders 5 and 8 in bank 2), the system optimizes the gas exchange process to reduce rotational non-uniformity. This parameter change improves running smoothness while maintaining optimal combustion efficiency, avoiding the fuel penalty associated with other corrective measures.
3Reliability
If higher idling speed is maintained, then engine stability is ensured, but idling fuel consumption increases
Solution Approach 1:
By implementing localized valve lift optimizations in specific cylinders, the patent equalizes the work output across all cylinders, reducing rotational non-uniformity and vibrations at idle. This creates a more stable idle operation that allows the engine to maintain stability at lower speeds, thereby reducing idling fuel consumption without compromising engine reliability.
Data Source
Figure 1~2
AI summary
The invention relates to an internal combustion engine having eight cylinders in V-configuration, wherein a first cylinder bank (9) is formed by a first, second, third and fourth cylinder (1, 2, 3, 4) disposed side by side in series and a second cylinder bank (10) disposed opposite of the first cylinder bank (9) is formed by a fifth, sixth, seventh and eighth cylinder (5, 6, 7, 8) disposed side by side in series. The internal combustion engine comprises a cross-plane crankshaft and has a firing order of a 90° crank angle from cylinder to cylinder. An intake camshaft and an exhaust camshaft are associated with each cylinder bank for actuating at least one intake gas exchange valve and one exhaust gas exchange valve for each cylinder (1, 2, 3, 4, 5, 6, 7, 8). The gas exchange intake valves of said cylinders (1, 2, 3, 4, 5, 6, 7, 8) of each cylinder bank (9, 10) that are actuated at a 90° crank angle in same cylinder bank (9, 10) have a larger valve stroke than the gas exchange intake valves in same cylinder bank (9, 10) actuated immediately prior thereto, wherein the gas exchange intake valves in same cylinder bank (9, 10) actuated immediately prior thereto have a smaller valve stroke than all the remaining gas exchange intake valves of both cylinder banks (9, 10). By virtue of the embodiment according to the invention, the smoothness of a generic internal combustion engine having eight cylinders in V-configuration is substantially improved, in particular when in neutral and in part-load operation.