Variable air intake system

Abstract

A valve closing side engaging groove is formed in a circumferential surface of a collar of a clutch between an optimum angular position, which implements a most effective valve angle for making the maximum fuel consumption improving effect, and a valve closing side least effective angular position, which implements a valve closing side least effective valve angle. Similarly, a valve opening side engaging recess is formed in the circumferential surface of the collar between the optimum angular position and a valve opening side least effective angular position, which implements a valve opening side least effective valve angle. Each of the grooves is engageable with a roller to securely hold the roller in corporation with a driven-side rotator to limit rotation of the driven-side rotator in a deenergized state of a motor.

1 . A variable air intake system for an internal combustion engine, comprising:
 an electric motor that is rotated to generate a rotational force in an energized state of the electric motor;   a valve that is placed in an air intake passage of the internal combustion engine and is rotated by the rotational force transmitted from the electric motor to adjust intake air supplied to the internal combustion engine through the air intake passage; and   a clutch that is placed between the electric motor and the valve to enable transmission of the rotational force from the electric motor to the valve and to disable transmission of a rotational force from the valve to the electric motor, wherein:   the clutch includes:
 a driving-side rotator that is rotated by the rotational force transmitted from the electric motor and includes a plurality of circumferential side engagement releasing projections, each of which circumferentially projects from a corresponding adjacent part of the driving-side rotator that is adjacent to the circumferential side engagement releasing projection; 
 a driven-side rotator that is coaxial with the driving-side rotator and is rotated by the driving-side rotator upon circumferential engagement with the driving-side rotator to rotate the valve in the energized state of the electric motor; 
 an annular collar that is non-rotatably held and has a circumferential surface, which is coaxial with the driven-side rotator, wherein a radial gap is formed between an engaging portion of the driven-side rotator and the circumferential surface of the collar and includes first and second circumferential side gap sections and a circumferentially intermediate gap section, which are arranged in such a manner that the circumferentially intermediate gap section is circumferentially placed between the first and second circumferential side gap sections and has a radial size larger than a radial size of any of the first and second circumferential side gap sections; and 
 an engageable element that is circumferentially placed between the first and second circumferential side gap sections in the radial gap, wherein a radial size of the engageable element is smaller than the radial size of the circumferentially intermediate gap section and is larger than the radial size of any of the first and second circumferential side gap sections, and the engageable element is circumferentially displaceable by a corresponding one of the plurality of circumferential side engagement releasing projections at a time of driving the driven-side rotator by the driving-side rotator; 
   the clutch and the valve are synchronized to satisfy all of the following conditions:
 when the driving-side rotator is rotated to rotate the driven-side rotator and thereby to place the engageable element in a first angular position along the circumferential surface of the collar, the valve is placed in a most effective valve angle, at which a fuel consumption improving effect of the intake air supplied from the valve to the internal combustion engine through the air intake passage is maximized; 
 when the driving-side rotator is rotated to rotate the driven-side rotator and thereby to displace the engageable element in a first circumferential direction from the first angular position to a second angular position along the circumferential surface of the collar, the valve is rotated in a valve closing direction from the most effective valve angle to a valve closing side least effective valve angle, at which the fuel consumption improving effect of the intake air supplied from the valve to the internal combustion engine through the air intake passage is reduced to zero; and 
 when the driving-side rotator is rotated to rotate the driven-side rotator and thereby to displace the engageable element in a second circumferential direction, which is opposite from the first circumferential direction, from the first angular position to a third angular position along the circumferential surface of the collar, the valve is rotated in a valve opening direction from the most effective valve angle to a valve opening side least effective valve angle, at which the fuel consumption improving effect of the intake air supplied from the valve to the internal combustion engine through the air intake passage is reduced to zero; 
   a valve closing side engaging recess is formed in the circumferential surface of the collar between the first angular position and the second angular position and is engageable with the engageable element to securely hold the engageable element in cooperation with the engaging portion of the driven-side rotator in the de-energized state of the electric motor; and   a valve opening side engaging recess is formed in the circumferential surface of the collar between the first angular position and the third angular position and is engageable with the engageable element to securely hold the engageable element in cooperation with the engaging portion of the driven-side rotator in the de-energized state of the electric motor.   
   
   
       2 . The variable air intake system according to  claim 1 , further comprising a speed reducer that is placed between the electric motor and the valve to reduce a rotational speed of rotation, which is originated from the electric motor and is conducted to the speed reducer, wherein a speed reduction ratio G of the speed reducer satisfies relationships of γ 1 /G≦α and γ 2 /G≦β where:
 γ 1  denotes an angular difference between the first angular position and an angular position of the valve closing side engaging recess along the circumferential surface of the collar;   α denotes an angular difference between the most effective valve angle and the valve closing side least effective valve angle;   γ 2  denotes an angular difference between the first angular position and an angular position of the valve opening side engaging recess along the circumferential surface of the collar; and   β denotes an angular difference between the most effective valve angle and the valve opening side least effective valve angle.   
   
   
       3 . The variable air intake system according to  claim 1 , wherein:
 the collar is placed radially outward of the driving-side rotator and the driven-side rotator; and   the circumferential surface of the collar is an inner circumferential surface of the collar.   
   
   
       4 . The variable air intake system according to  claim 1 , wherein the engageable element is a roller, which is rollable along the circumferential surface of the collar. 
   
   
       5 . The variable air intake system according to  claim 4 , wherein each of the valve closing side engaging recess and the valve opening side engaging recess is in a form of a groove, into which a portion of an outer peripheral surface of the roller is engageable. 
   
   
       6 . The variable air intake system according to  claim 1 , wherein:
 the engageable element has a circular cross section;   each of the valve closing side engaging recess and the valve opening side engaging recess has an arcuate surface; and   a radius of curvature of the arcuate surface of each of the valve closing side engaging recess and the valve opening side engaging recess is generally the same or slightly larger than that of the circular cross section of the engageable element.   
   
   
       7 . The variable air intake system according to  claim 1 , wherein an optimal position engaging recess is formed in the circumferential surface of the collar at the first angular position and is engageable with the engageable element to securely hold the engageable element in cooperation with the engaging portion of the driven-side rotator in the de-energized state of the electric motor. 
   
   
       8 . The variable air intake system according to  claim 1 , wherein:
 the engageable element is positionable in a securely engaged state when the engageable element is circumferentially moved from the circumferentially intermediate gap section toward one of the first and second circumferential side gap sections and is securely held between the engaging portion of the driven-side rotator and the circumferential surface of the collar upon rotation of the driven-side rotator induced by the rotational force transmitted from the valve in a de-energized state of the electric motor; and   the engageable element is positionable in a released state when the engageable element held in the securely engaged state is circumferentially pushed by one of the plurality of circumferential side engagement releasing projections of the driving-side rotator toward the circumferentially intermediate gap section to release the engageable element from the securely engaged state and thereby to permit integral rotational movement of the driving-side rotator, the driven-side rotator and the engageable element in the energized state of the electric motor.