Method and apparatus for controlling operation of dual mode hcci engines

Abstract

An intake and exhaust system for a dual mode HCCI engine, which provides superior intake temperature control and homogeneity for engine operation in SI and HCCI modes, as well as during transition between SI and HCCI modes and vice-versa. The system includes adjusted intake cam movement event lengths for intake valve operation at specified modes of operation. The system further includes at least one cam profile switching device operatively connected to intake and exhaust valves in an engine for controlling event length, maximum lift, and valve opening / closing timings for the intake and exhaust valves. The system yet further includes a bifurcated intake system and camless valve actuators for controlling intake valves for facilitating operation in SI or HCCI modes, as well as transition between SI and HCCI modes and vice-versa.

Description

BACKGROUND OF INVENTION [0001] a. Field of Invention [0002] The invention relates generally to intake and exhaust systems for engines, and, more particularly to the control of an intake and exhaust system for a dual mode HCCI engine, which provides superior intake temperature control and homogeneity for engine operation in SI and HCCI modes, as well as during transition between SI and HCCI modes and vice-versa. [0003] b. Description of Related Art [0004] Compared to conventional engines, homogeneous charge compression ignition (HCCI) engines potentially have high efficiency, very low emissions of oxides of nitrogen (NOx) and particulates, and relatively low cost. HCCI engines however generally operate over the same operating range, with regard to speed and torque, as conventional SI or diesel engines, for achieving the same vehicle performance. Because HCCI is limited by harsh combustion at higher torques, it is common for the engine to employ both SI and HCCI combustion mode techno...

AI Technical Summary

Benefits of technology

[0015] The invention solves the problems and overcomes the drawbacks and deficiencies of prior art intake and exhaust systems by providing novel intake and exhaust systems for a dual mode HCCI engine, which provide superior intake temperature and pressure control for engine operation in SI and HCCI modes, as well as during transition between SI and HCCI modes.

[0016] Thus, exemplary aspects of the present invention are to provide a system for precisely controlling each cylinder's inlet air temperature and density in order to promote efficient and stable HCCI combustion, an intake system / strategy that can control both the overall air-fuel charge temperature and the heterogeneity of temperature distribution in a cylinder, as well as a system which can facilitate a HCCI-SI combustion mode transition.

Problems solved by technology

Because HCCI is limited by harsh combustion at higher torques, it is common for the engine to employ both SI and HCCI combustion mode technology.

If the temperature is too high, the radicals can autoignite too early, creating excessive peak pressures, poor efficiency and other issues (i.e. engine damage).

If the temperature is too low, the radicals may not combust at all, creating a misfire condition.

Accordingly, the intake / exhaust system for a dual-mode HCCI engine can be relatively complicated and can include several factors which can effect the performance thereof, as evidenced by the aforementioned discussion.

One drawback with the invention of Flynn is that it requires the continuous varying of valve timing, which can be difficult to implement for the HCCI and SI combustion mode transition region.

Further, the results from these tests are not directly applicable to engines with a high geometric compression ratio (CR>˜15:1).

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