US2742884A - Correcting device for the timing of the ignition in internal combustion engines - Google Patents

Description

INES

April 24, 1956 o. GAGLIO CORRECTING DEVICE FOR THE TIMING OF THE IGNITION IN INTERNAL COMBUSTION ENG Filed Jan, 9, 1953 INVENTOR. OSWO. (l G; 1% 9 BY.

WMMsQQM CORRECTI'NG'DEVICE FOR THE TIMING OF THE EHISIIEEION .lN INTERNAL COMBUSTION EN- My inventionrhas for its object a correcting device for thetimingof the ignition in internal combustion engines of the type resorting to the depression produced in the suction pipe with a view to modifying the ignition advance through the agency of a control member, which correcting device includes means limiting the stroke of said member controlling the advance, said means being directly controlled bythe'accelerator provided on the engine in a manner such that the correction of the advance may be executed in a very gradual manner. In accordance with my invention, the accelerator acts through the agency of a stop-forming cam which is constrained to be angularly shifted under the action of the movements of the' accelerator so as to define, as a function of said-angular setting givento said cam, the extreme position of the member controlling the advance in accordance with the suction exerted by the engine.

I have illustrated in the single figure of accompanying drawing a preferred embodiment of my invention.

In said drawing, 1 designates the intake pipe of the engine acting through the branch pipe 4 on the pressure prevailing inside a chamber constituted inside a block B and one of the surfaces of which is constituted by a diaphragm 7 which drives in its turn, when submitted to the suction transmitted to said chamber and acting against the compensating spring R, the disc 14 which produces the advance of ignition; the connection between the diaphragm 7 and the disc 14 is provided by the slider 9 that is secured to the diaphragm and forms the control member the stroke of which is limited, as will be disclosed hereinafter, said slider 9 being pivotally secured to the connection rod 13 keyed to the disc 14 which is in its turn keyed to the cam shaft 15 of the ignition system.

On the other hand, the accelerator, that is not illustrated, acts primarily on the conventional throttle valve 2 and, furthermore, through the pivotal connection 21 and the linkage 3 on a rockable lever 11. The accelerator, when it acts on the throttle valve 2, causes consequently the lever 11 to revolve round its axis XX in unison with the rod 8. The latter passes through a recessed part, having a rectangular cross-section, formed in the block B so as to pass through the slider or controlmember 7 and slidingly engaging said recessed part of the block. The part of the rod 8 passing through the corresponding recess D in the slider 9 is shaped so as to form a cam adapted to urge the slider towards the left hand side of the figure against the action of the diaphragm 7 that is submitted to the suction transmitted through the pipe 4; the stroke of the diaphragm towards the left hand side is limited in the absence of any suction by the thrust of a member rigid with the diaphragm against an element G of the block B.

The outline of the portion of the rod 8 passing through the recess D in the slider 9 is such that when the rod 8 rocks and moves away from the position illustrated, said rod defines a more or less considerable length of stroke for the diaphragm submitted to suction within the limits allowed by the shifting of the slider with reference to cam extending through the recess in the control the section of the rod facing it at any moment; thus, the suction exerted on the diaphragm 7 may, through the slider 9, shift the connecting rod 13. providing for the desired correction of the ignition timing within the limits defined ,by the accelerator acting on the rod 8 forming a stop-shaped cam.

The shifting and the stroke of the diaphragm submitted to a reduction in pressure by the engine are thus controlled and limited by the action of the accelerator on the correcting means through the agency of the stop constituted by the cam formed by the shaped portion of the spindle 8.

The system includingv the lever 11 and the rod 8 is always urged back into its inoperative position illustrated inthe drawing, for which the stop rigid with the diaphragm engages the part G of the block B. This location of the lever-11 and of the rod 8 is defined by the'coil spring 12 connecting the rod 8 with the stationary block B.

The arrangement described damps thus, during any slow and gradual acceleration, any too speedy shifting of the diaphragm under the action of the large suction exerted by the engine between the first and third eighths of the accelerator stroke and constrains the diaphragm to execute, in spite of the considerable modifications in the depression, a logical advance for the ignition in accordance with the gradual shifting any harsh action and without any knocking during the gradual picking-up of speed.

Furthermore, the sensitivity of the compensating spring R acting on the diaphragm may be much higher than in arrangements that do not include such a damping of the action of high reductions in pressure. On the other hand, during an energetic or complete acceleration, the depression produced by the engine is not sufiicient or else, is completely lacking at first so that, with such an operation of the accelerator, the diaphragm is not controlled by the depression and remains at first in its original position without acting on the timing of the ignition; however, by reason of the larger sensitivity of the spring R, the diaphragm returns speedily towards its operative position and acts on the slider 9 as it responds to the suction exerted by the engine, the shifting of the slider being stopped only by the thrust against the cam constituted by the rod 8 as defined hereinabove. It is thus possible to obtain, through the agency of the arrangement described, a gradual curve of ignition advance extending over a comparatively long duration or again, a short curve having a rapid slope, according to the manner of operating of the engine, the ignition advance being adjusted automatically by the reduction in pressure produced by the engine and associated with the mechanical correction produced by the accelerator.

Obviously, various modifications may be brought to the arrangement disclosed without unduly widening thereby the scope of the invention, as defined in accompanying claims.

What I claim is:

1. In an arrangement for the timing of the ignition of an internal combustion engine provided with an accelerator, the combination of a control member for the advance of ignition, said member being provided with an inner recess, means whereby the depression in the suction pipe of the engine acts on said control member, a stop-forming member and adapted to limit the stroke of said control member in the advance-increasing direction and a leverage connecting said cam with the accelerator to make the angular setting of said cam depend on the position of the accelerator.

2. In an arrangement for the timing of the ignition of an internal combustion engine, the combination of a stationary block provided with an inner recess, a slider adapted to slide inside the recess in said block and pro vided with an aperture perpendicular to its direction of of the accelerator without movement, means controlling the movements of said slider and controlled in their turn by the suction of the engine, a rotary cam-shaped member extending inside the aperture in the slider and adapted to rock round an axis perpendicular to the direction of movement of said slider, said cam-shaped member defining through its relative angular setting with reference to its axis the end of .the operative stroke of said slider, means whereby the accelerator controls the angular setting of ,said camshaped member and means whereby the slider controls the advance of the ignition.

3.1m an arrangement for the timing of the ignition of an internal combustion engine provided with asuction pipe, .the combination of a stationary blockprovided with an innerrecess, a slider adapted to slide inside the recess in said'block and provided with an aperture perpendicular to its direction of movement, a chamber being provided inside said block and communicating with the suction pipe of the engine, a diaphragm stretched inside the chamber and submitted to the action of the suction transmitted through said pipe, means rigidly connecting the inner end of the slider with the central portion of said diaphragm, means rigid with said diaphragm and engaging the wall of the chamber opposed to the suction pipe when no substantial suction is exerted on the diaphragm to limit the inoperative return stroke of the slider rigid with the central portion of said diaphragm, a rotary cam-shaped member extending inside the aperture in the slider and adapted to rock round an axis perpendicular to the directio nof movement of said slider, said cam-shaped member defining through its relative angular setting with reference to its axis the end of the operative stroke of said slider,

means whereby the accelerator controls the angular setting of said cam-shaped member and means whereby the slider controls the advance of the ignition.

4. In a semi-automatic control system for the ignition timing mechanism in an internal combustion engine provided with a carburetor, including a throttle valve controlled by .an accelerator pedal, ,the combination ,of .a

shiftable member submitted to the suction prevailing in the vicinity of the throttle valve, a sliding link operatively connected with said member and adapted to move along a rectilinear path and to-control the timing mechanism in accordance with the location assumed by it on said path, a cam of variable radius revoluble round an axis perpendicular to the path of the sliding link and forming a stop for the latter as said sliding link progresses along its rectilinear path in an ignition advancing movement, means controlled by the accelerator pedal and controlling the angular position of the cam to define the maximum advance of the timing mechanism for the position of the vthrottle valve and elastic means urging the cam back towards its position corresponding to closure of the throttle valve.

References Cited in the file of this patent UNITED STATES PATENTS 1,797,838 Prescott Mar. 24, 1931 1,969,682 Arthur Aug. 7, 1934 2,473,171 Ostling June 14, 1949 FOREIGN PATENTS 168,381 Great Britain Aug. 29, 1921

Images