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Method and apparatus for controlling operation of dual mode hcci engines

a dual-mode hcci engine and control system technology, applied in the direction of electric control, machines/engines, output power, etc., can solve the problems of misfire condition, excessive peak pressure, poor efficiency and other issues, etc., to facilitate the transition between hcci-si combustion mode and promote efficient and stable hcci combustion

Inactive Publication Date: 2005-08-25
FORD GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides a system for controlling the temperature and pressure of an engine's inlet air and exhaust gases in both a single-mode and dual-mode HCCI engine. The system includes a cam profile switching device that can control the intake and exhaust valves in a cylinder, allowing for efficient and stable HCCI combustion in both modes. The system also includes a piston disposed within the cylinder, intake and exhaust valves, and a cold-air duct and hot-air duct for supplying cold and hot air to the cylinder. The cam profile switching device can switch the event length of the intake and exhaust valves, as well as the normalized valve maximum lift and closing time of the valves. The system provides precise control over the engine's inlet air and exhaust gases for optimal performance in both modes.

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).

Method used

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  • Method and apparatus for controlling operation of dual mode hcci engines
  • Method and apparatus for controlling operation of dual mode hcci engines
  • Method and apparatus for controlling operation of dual mode hcci engines

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first embodiment

[0048] Referring to FIGS. 1-3, intake / exhaust system 10 is disclosed. For the embodiment of FIGS. 1-3, generally, there is described an HCCI-SI dual-mode engine system with a geometric compression ratio of approximately 15:1, which is higher than those of conventional SI engines. In order to operate an engine in both HCCI and SI modes, to achieve HCCI-SI combustion mode transition, and to operate an engine at high load (˜10 bar BMEP), the proposed engine system according to the present invention has the following features discussed herein in reference to FIGS. 1-3.

[0049] As illustrated in FIG. 1, there are disclosed proposed engine intake and exhaust valve timings and lifts according to the present invention. The valve lift profiles illustrated in FIG. 1 allow the use of cam profile switching as one of the major means to change the combustion mode between HCCI and SI by allowing the use of high engine geometric compression ratio. In the embodiments discussed herein, the cam profile ...

second embodiment

[0057] the present invention, which addresses heterogeneity of in-cylinder temperature, will be discussed in detail below in reference to FIGS. 4-7.

[0058] With regard to the second embodiment, in HCCI mode, an intake system can promote heterogeneity of the in-cylinder temperature distribution, hence reducing the overall combustion rate for a cylinder. During HCCI-SI combustion mode transition at engine speeds below 3000 rpm, an intake system can promptly change the air-fuel charge temperature, the residuals ratio, the intake pressure, as well as the effective compression ratio (intake valve closing time). In SI mode at high engine speeds up to 6000 rpm, an intake system can use all (two or more) intake valves per cylinder to achieve high volumetric efficiency, and can operate with boosted intake pressure. For the present invention, it is also desirable to switch the combustion mode in different cylinders at different times to achieve a smooth transition.

[0059] Based upon the aforem...

third embodiment

[0065] the present invention, which provides for further improvement in control of the combustion mode transition, will be discussed in detail below in reference to FIGS. 8-10.

[0066] Referring to FIG. 8(a), in order to improve the control of the combustion mode transition process, the third embodiment of the present invention uses two cam profile switching devices 35, 37 per cylinder for both cold and hot intake valves 24, 26, respectively, and a single cam profile switching device 23 for exhaust valves 27. For example, whereas the second embodiment for FIG. 5(a) uses a single cam profile switching device 25 for cold intake valve 24, the third embodiment of FIG. 8(a) uses two cam profile switching devices 35, 37 per cylinder for cold and hot intake valves, 24, 26, respectively. One advantage of using two cam profile switching devices is that the change of the throttle angle may be decreased without jeopardizing engine performance.

[0067] Specifically, lift curves 43, 44 for cold int...

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PUM

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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...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F01L1/34F02B1/02F02B1/12F02B17/00F02D13/02F02D41/30F02F3/26
CPCF02B1/02F02B1/12F02D13/0207F02D13/0253F02D13/0257F02D13/0265Y02T10/18F02D41/3035F02D41/3064F02D2041/001Y02T10/128Y02T10/142F02D13/0269Y02T10/12
Inventor YANG, JIALINBOYER, BRADKU, KIMSHUI, FANGSTOCKHAUSEN, WILLIAM
Owner FORD GLOBAL TECH LLC
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