Intake device for an internal combustion engine

An intake system for an internal combustion engine having at least one intake port for receiving a charge mixture and mixture development means for preparing said charge mixture, said intake system supplying air thereto and comprising:

• a relatively short fixed intake pipe forming a high speed inlet tract tuned for high engine speed operation, said fixed intake pipe having a high speed intake opening;
• a guide pipe separated from said intake opening of said fixed intake pipe and having an intake tract terminating in a low speed intake opening;
• a moveable intake pipe movably mounted on said guide pipe so as to selectively abut said fixed intake pipe to collectively form a low speed inlet tract with said fixed intake pipe and said guide pipe, said low speed inlet tract being tuned for low engine speed operation;
• said moveable intake pipe moving from a low speed position spaced away from said fixed intake pipe to a high speed position in abutment with said fixed intake pipe, said internal combustion engine being susceptible to a transient power drop during movement of said moveable intake pipe through positions intermediate therebetween;
• and
• transient power drop reduction means for reducing at least the duration of transient power drop relative to the speed of movement of said moveable intake pipe.

An intake system for a multi-cylinder combustion engine having at least two intake ports for receiving a charge mixture and mixture development means for preparing said charge mixture, said intake system supplying air thereto and comprising:

• a purality of relatively short fixed intake pipes, a fixed intake pipe being associated with each engine cylinder and forming a high speed inlet tract tuned for high engine speed operation, each said fixed intake pipe having a high speed intake opening;
• a plurality of guide pipes, a guide pipe being associated with each engine cylinder and being separated from said intake opening of its associated said fixed intake pipe and having an intake tract terminating in a low speed intake opening;
• a plurality of moveable intake pipes, a moveable intake pipe being associated with each engine cylinder and being moveably mounted on its associated said guide pipe so as to selectively abut its associated said fixed intake pipe to collectively form a low speed inlet tract with said fixed intake pipe and said guide pipe, said low speed inlet tract being tuned for low engine speed operation;
• drive means for shifting each of said moveable intake pipes between said high speed position and said low speed position, said drive means differentially driving said moveable intake pipes of different cylinders with slightly different timings so that the transient power drop associated with different said cylinders occurs at slightly different times to reduce the total transient power drop at any given time occurring in said multi-cylinder engine.

An intake system for a multi-cylinder internal combustion engine having a plurality of intake ports for receiving a charge mixture and mixture development means for preparing said charge mixture, said intake system supplying air to said internal combustion engine via said mixture development means, comprising:

• variable length intake tract means for providing an adjustable effective length intake tract tuned to the rotational speed of said engine for each said cylinder;
• said variable length intake tract means developing a transient power drop in each said cylinder during adjustment of the effective length of said intake tract;
• and
• drive means for adjusting the effective length of the intake tract, said drive means varying the timing of the adjustment of effective length between different said cylinders so that the transient power drop associated with different said cylinders occurs at different times to reduce the total transient power drop in said multi-cylinder engine at any given time.

A method of supplying charge to an internal combustion engine to improve the performance thereof, the internal combustion engine having at least one intake port for receiving a charge mixture and a carburetor mounted to said input port said method comprising:

• (a) supplying charge to the engine with a carburetor mounted to said intake port;
• (b) varying the effective length of the intake tract providing air to said intake port through said carburetor to enhance the performance of said engine;
• and
• (c) varying the air flow resistance of the intake system including said carburetor and intake tract in conjunction with said step (b) to correct the air/fuel ratio provided to said intake port by said carburetor to reduce the influence of positive pressure waves on said air/fuel ratio.