US3561411A

US3561411A - Technique and device for improving the combustion as well as the performance of spark-ignition engines operating at altitude

Info

Publication number: US3561411A
Application number: US755636A
Authority: US
Inventors: Adrain Calin Vasilescu; Ion Stefa
Original assignee: MINI IND CONSTRUCTILLOR
Current assignee: MINI IND CONSTRUCTILLOR; MINISTERUL INDUSTRIEI CONSTRUCTIILOR DE MASIN
Priority date: 1968-08-27
Filing date: 1968-08-27
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09

Abstract

Internal-combustion ignition system in which the distributor has a pivotable spark-advance disc angularly displaceable relatively to the distributor cam and shiftable by a diaphragm subjected to reduced pressure of the engine (intake manifold) in order to permit compensation of the spark timing or variation in engine operation. The device includes a hermetically sealed capsule effective to shift the spark-advance disc or plate in the direction in which the reduced pressure of the engine is effective so as to increase the advance as air density decreases with increasing altitude. A vacuum line runs from the diaphragm to the manifold.

Description

Unite States atent [54] TECHNIQUE AND DEVICE FOR IMPROVING THE COMBUSTION AS WELL AS THE PERFORMANCE OF SPARK-IGNITION ENGINES OPERATING AT ALTITUDE 8 Claims, 4 Drawing Figs. [52] U.s. Cl 123 117, 200/31 [50] Field otSearch 123/l17.1; 200/31 Ill/I [56] References Cited UNITED STATES PATENTS 2,646,781 7/1953 Doyen 123/1 17.1 2,731,523 1/1956 Downing 123/117.1 2,778,892 l/l957 Vanderpoel 200/31 Primary Examiner-Douglas Hart An0rneyl(arl F. Ross ABSTRACT: Internal-combustion ignition system in which the distributor has a pivotable spark-advance disc angularly displaceable relatively to the distributor cam and shiftable by a diaphragm subjected to reduced pressure of the engine (intake manifold) in order to permit compensation of the spark timing or variation in engine operation. The device includes a hermetically sealed capsule effective to shift the spark-advance disc or plate in the direction in which the reduced pressure of the engine is effective so as to increase the advance as air density decreases with increasing altitude. A vacuum line runs from the diaphragm to the manifold.

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TECHNIQUE AND DEVICE FOR IMPROVING THE COMBUSTION AS WELL AS THE PERFORMANCE OF- SPARK-IGNITION ENGINES OPERATING AT ALTITUDE Our present invention relates to-a method of and a system for the improved operation of internal-combustion engines triggered by the initiation of spark discharges in accordance with a predetermined timing sequence.

In a internal-combustion engine, ignition is generally initiated by subjecting the spark plugs of the engine to high voltage pulses in accordance with a predetermined cycle. To this end, a distributor maybe provided with a plurality of distributor contacts corresponding to the number of spark plugs and with a set of breaker points which open and close the supply circuit to the ignition coil. In such a distributor, a rotary cam driven by the crank shaft or cam shaft, opens and closes the breaker points and drives the distributor rotor. The distributor is provided in a conventional manner with a breaker plate or other angularly displaceable element, the angular displacement of which controls the spark advance; the spark advance is generally a function of reduced pressure communicated from the intake manifold of the engine to a mechanism which correspondingly increases or decreases the timing of the ignition pulse in accordance with the operating conditions of the vehicle. Thus, in cases of partial load, spark advance is in creased in order to improve the combustion process and the engine performance.

Furthermore, as the altitude at which the engine is intended to operate increases, the air density diminishes and the fuel mixture becomes enriched. It has not been possible heretofore to satisfactorily correct the altitude phenomena without detrimentally affecting the development of the combustion within these engines. In fact, it is recognized that elevated altitudes give rise to a situation in which maintenance of constant power has the effect of operating the engine under strain. All automatic devices heretofore proposed may undergo damage and fail to reduce the advance of the spark when normal al-' titude is reached, thereby producing a further diminution with detrimental effect upon engine performance and combustion.

It is therefore, an important object of the present invention to provide an improved system for the control of the ignition in an automotive-vehicle engine or other internal-combustion engine operating in accordance with the OTTO cycle, whereby the the aforementioned disadvantages can be obviated.

Still another object of this invention is to provide an improved system for controlling an internal-combustion engine which is adapted to operate at both high and low altitudes.

According to the principal feature of this invention, an internal-combustion-engine distributor, having a spark sparkadvance chamber which is angularly shiftable relatively to the breaker cam in one sense by the manifold vacuum, is provided with a barometric device capable of augmenting the effect of the manifold vacuum at high altitudes and of attenuating this effect at low altitude and atmospheric pressures.

In one embodiment of the present invention, the barometric device comprises a hermetically sealed bellows-type capsule which acts upon the angularly shiftable member via a rod or other carrying means.

The barometric device may be located remote from the diaphragm adapted to be actuated by the manifold pressure or, in another embodiment, may be disposed between this diaphragm and the distributor housing.

Still another embodiment of this invention provides a capsule of the character described in a valve system adapted to bleed ambient air into the diaphragm chamber which is subjected to section. When the bellows-type capsule expands, therefore, the bleeding opening is closed and the manifold vacuum exerts maximum effect. On the other hand, when the capsule contracts, the valve is opened and a suction effect is produced. Consequently the advance of the spark is promoted in spite of the fact that the engine is located at a high altitude and correct combustion is ensured.

Furthermore, since the capsule and the barometric device is filled with air at normal temperature and pressure, the device is not subjected to substantial stress under normal operating conditions. Even with failure of the device at elevated altitudes, e.g. as a result of leakage of gas from the capsule, no substantial disadvantage arises since such failure merely renders the barometric correction system inoperative but has no effect upon the normal spark-advance operation.

The invention will be described in greater detail hereinafter with reference to the accompanying drawing in which:

FIG. 1 is a plan view, partly in diagrammatic form and with parts in sections, illustrating the system of the present invention;

FIG. 2 is a view similar to FIG. 1 of an embodiment wherein a barometric correction device is located at the same side as the manifold-control diaphragm;

FIG. 3 is a view similar to FIGS. 1 and 2 and illustrating a third embodiment in which the barometric correction device operates upon the spark-advance element via a spring; and

FIG. 4 is a diagrammatic plan view of a system according to this invention using a bleeder valve.

In general, the distributor described below and illustrated in FIGS. 1 through 4 may be of any conventional type having a spark-advance element acted upon the by the diaphragm of a chamber connected with the intake manifold of the engine. Such distributors are described and illustrated at pages 20() ff. of PRINCIPLES OF AUTOMOTIVE VEHICLES, U.S. Government Printing Office, Washington DC, 1956.

The embodiment illustrated in FIG. I comprises a gas-filled bellows-type elastic capsule 1 which is hermetically sealed and may be composed of metal or a synthetic resin, the sole criterion being the ability of the device to expand with the deformation under the internal (normal atmospheric) pressure when the vehicle is operated at an elevated altitude.

The body of the ignition distributor is provided with a bracket 2 in which the threaded rod 10 is received and held adjustably between two nuts 1b and lc,the rod la being fixed to the rear wall of the capsule 1. In its forward wall the capsule 1 is provided with a rod 3 extending along a chord of the distributor in the direction of displacement (arrow A) of the manifold vacuum actuator. In this system the spark-advance member shown as an angularly shiftable disc 5 which is swingable in the clockwise sense (arrow B) about the axis C of the distributor in order to advance the spark. In the usual manner, the breaker cam 6 rotates in the opposite sense (i.e. counterclockwise) as represented by the arrow E. The member 5 is formed with a slot 50 which receives the bent end 4 of the rod 3 with a clearance Aa which prevents the temperature increase at low altitudes below 200 meters and corresponding expansion of member 1 from advancing the disc 5 excessively.

The intake manifold of the engine is coupled with an airtight chamber 8 via a fitting 8a and acts upon the membrane 9 spanning this membrane and coupled with the spark-advance plate 5 via a rod 10. The latter passes through a hollow post 8b leading to the housing diaphragm 9. A spring 7 is received in this housing and bears axially upon the membrane 9, thereby urging the latter and the rod 10 in the clockwise direction, i.e. opposite the direction of spark-advance (arrows A, B). A stop pin 11 is received in an arcuate slot 11a of the distributor disc to prevent excessive angular displacement of the electric electric-spark-advance mechanism.

In the embodiment of FIG. 2, in which a similar structure has been identified with similar numerals, the distributor is shown as a rotor cam 26 which nonnally rotated counter to the spark-advance displacement of thedistributor plate 25. A

slot 25a of the plate 25 receives the stop pin 25b, preventing excessive angular displacement of the plate 25. In this embodiment, however, the housing 28 of the diaphragm 29 has its vacuum chamber 28c connected by fitting 28b with the intake manifold.

On the other side of the diaphragm 29, we have provided a stack of

toroidal members

21a and 21b and 210 which are fastened together and form the hermetically sealed capsules of the present invention.

The capsule 21a --21c rests against a plate 28dcarried by a hollow piston 28b of the distributor housing. In this embodiment, only a single rod is used to a actuate the spark-advance disc. The rod 20 is affixed to the diaphragm 29 and passes through the tubular post 28b to a pin 24 which isre ceived with the clearance Aa in theopening 24a of the plate 25. Each of the

annular members

21a,21b, and 210 is filled with air at ambient pressure and temperature and is hermetically sealed, while being composed of elastic material. When the barometric device is inoperative, manifold suction connected to the chamber 28 draws the diaphragm 29 to the right against the force of spring 27 and rotates the disc in the clockwise sense to advance spark in the usual manner. When the altitude at which the engine operates increases, capsules 2111-21 expand (the external pressure being reduced) to shift the airtight chamber 28 to the right (arrow A). This movement is transmitted to disc 25 via the intermediary of rod 20 to rotate the disc 25 counter to the rotation of cam 26, thereby increasing the advance of the spark. When the surrounding pressure decreases as a result of return to lower altitude, the elastic capsule represented by the

rings

21a, 21b, and 21c contracts to return the disc 25 to its initial position.

in the system of FIG. 3, the gas-filled hermetically sealed expandable capsule 31 is fastened at one end to the bracket 32 whileits other end is provided with a rod 33 as previously described in connection with FIG. 1. In this embodiment,

however, a spring acts upon the spark-advance disc 35 to increase or decrease the effectiveness of the manifold pressure in chamber 38. The spring 33a is affixed at one end to a hook 33b of the rod 33 while the other end of the spring 33a is anchored to a pin 34 on the disc 35. The diaphragm 39 in this.

embodiment is received in the closed chamber 38, to which manifold suction is applied at 38a and is connected with the spark-advance disc 35 via the rod whose pivot 30a is located on the disc 35. The breaker cam, 36 rotates relative to the disc as represented by the arrow A.

in normal operation, the spring 33a need not be under a pretension so that normal response to manifold pressure (i.e. load and engine speed) results. The manifold pressure is applied to the diaphragm 39 which draws the rod 30 to the right (arrow A), thereby swinging disc 35 in the clockwise sense (arrow D) to advance the spark.

Spring 33a is thereby tensioned and, when the manifold suc-. tion is released, draws the disc 35 in the' opposite sense. When, however, the surrounding pressure decreases as a result in the increase in the operating altitude of the device, the capsule 31 expands and the spring force resisting clockwise displacement of the disc 35 decreases. in other words, the disc 35 responds more readily to the action of diaphragm 39 in the spark-advance direction. Consequently, when the same value of reduced pressure Ap is applied by the manifold, the force acting upon member 39 will rotate the disc 35 to a greater extent when the l altitude is higher and vice versa. v

in FIG. 4, we have shown still another embodiment wherein the barometric device influences the effectiveness of the manifold suction. In this system, air may be led into the chamber 48 which is subjected to the manifold pressure via a tube 44 in which a valve 44a is disposed. The actuating member of this valve is a rod 43 connected to the hermetically sealed capsule 41. The latter is of the type described in connection with FIGS. 1 and 3 and is anchored to a bracket 42 connected to the body of the distributor via a threaded rod 41a and the nuts 41b and 41c.

The normal manifold suction is applied to chamber 48 via the fitting 48aand draws the diaphragm 49 to the right (arrow A) to swing the spark-advance disc 45 in the clockwise sense (arrow B) when the spark-advance is desired. The breaker cam 46, of course, normally rotates in the opposite sense (arrow D). The diaphragm 49 is connected to the disc 45 via a rod 40 which is pivoted at 40a to the disc 45. The latter has an arcuate slot 51a in which a pin 51 of the distributor body is received. This pin limits the angular stroke of the disc and serves as one anchor for a tension spring 47 whose other end is attached at 47a to a pin connected with the disc 45.

As the operating altitude increases, the capsule 41 expands to close the valve 44a and therebyprevents the induction of air into the chamber 48 via the tube 44. The reduced pressure or suction within chamber 48, or given manifold condition, is increased and the force upon disc 45 is increased as well. When the altitudedecreases, the valve 44a opens slightly to reduce the pressureinchamber 48 and thereby renders the manifold pressure thus effective. When the altitude decreases. spring 47 serves to rotate the disc 45 back-toits original position. In each of the embodiments described, a leak in the elastic capsules will merely render the barometric device ineffective but will not cause a sharp increase in the spark-advance at low altitudes.

We claim:

1. In a distributor system of fora spark-ignition engine wherein a spark-advance disc member is angularly displaceable in response to manifold pressure to'advance the spark timing in accordance with engine-operating conditions, the improvement which comprises in combination, a housing member forming a pressure-tight chamber, a diaphragm in said chamber subdividing the interior into two compartments, means for connecting one of said chambers to the manifold of V the engine for subjecting said diaphragm to manifold pressure,

a rod directly connecting said diaphragm with said disc member, and a barometric device independent of said rod and operatively connected with one of said members for augment- 2. The improvement defined in claim 1 wherein said barometric device is hermetically sealed in an elastic capsule adapted to expand upon increase in operating altitude.

3. The improvement defined in claim-2 whereinthe means coupling said diaphragm to said member is rod and said capsule controls the displacement of said rod.

4. The improvement defined in claim 3 wherein said chamber is provided with valve means venting the same to the atmosphere, further comprising means connecting said cap sule with said valve means whereby expansion of said capsule closes said valve means and contraction of said capsule opens said valve means.

5. The improvement defined in claim 3 wherein said capsule is interposed between said chamber and said distributor and expansion of said capsule shifts said diaphragm in the direction of displacement thereof .with increasing suction in said chamber.

6. in a distributor system for a spark-ignition engine wherein a spark-advance member is angularly displaceable in response to manifold pressure to advance the spark in accordance with engine operating conditions, the improvement which comprises a barometric device operatively connectedwith said distributor for augmenting said angular displacementof said member upon operation of the engine at an elevated altitude, said distributorincluding a pressure-tight chamber adapted to be subjected to manifold pressure, a diaphragm is in said chamber displaceable by said manifold pressure and means operatively connecting said diaphragm to said member for angularly displacing said diaphragm, said barometric device being hermetically sealed in an elastic capsule adapted to expand upon increase in operating altitude and the means coupling said diaphragm to said member including a rod whose displacement iscontrolled by ,said capsule, said capsule being interposed between said chamber and said distributor whereby expansion of said capsule shifts said diaphragm in the direction of displacement thereof with increasing suction in said chamber, said capsule being generally toroidal and said rod passingthrough said capsule.

7. The improvement defined in claim 2 wherein said means coupling said diaphragm to said member is a rod adapted to draw said member in one sense with increasing suction in said chamber, spring means connecting said capsule with said member increasing resistance to displacement of said member by said rod at relatively low altitudes and decreasing resistance to displacement of said m tively higher altitudes.

ember by said rod at relaclaim 2, further comprising said member for rotation of sion and contraction of said

Claims

1. In a distributor system of for a spark-ignition engine wherein a spark-advance disc member is angularly displaceable in response to manifold pressure to advance the spark timing in accordance with engine-operating conditions, the improvement which comprises in combination, a housing member forming a pressure-tight chamber, a diaphragm in said chamber subdividing the interior into two compartments, means for connecting one of said chambers to the manifold of the engine for subjecting said diaphragm to manifold pressure, a rod directly connecting said diaphragm with said disc member, and a barometric device independent of said rod and operatively connected with one of said members for augmenting said angular displacement of said disc member upon operation of the engine at an elevated altitude, said member and said rod interengaging with limited play adapted to prevent displacement of said member with temperature increases to expand the said capsule at an altitude below about 200 meters.

2. The improvemenT defined in claim 1 wherein said barometric device is hermetically sealed in an elastic capsule adapted to expand upon increase in operating altitude.

3. The improvement defined in claim 2 wherein the means coupling said diaphragm to said member is rod and said capsule controls the displacement of said rod.

4. The improvement defined in claim 3 wherein said chamber is provided with valve means venting the same to the atmosphere, further comprising means connecting said capsule with said valve means whereby expansion of said capsule closes said valve means and contraction of said capsule opens said valve means.

5. The improvement defined in claim 3 wherein said capsule is interposed between said chamber and said distributor and expansion of said capsule shifts said diaphragm in the direction of displacement thereof with increasing suction in said chamber.

6. In a distributor system for a spark-ignition engine wherein a spark-advance member is angularly displaceable in response to manifold pressure to advance the spark in accordance with engine operating conditions, the improvement which comprises a barometric device operatively connected with said distributor for augmenting said angular displacement of said member upon operation of the engine at an elevated altitude, said distributor including a pressure-tight chamber adapted to be subjected to manifold pressure, a diaphragm is in said chamber displaceable by said manifold pressure and means operatively connecting said diaphragm to said member for angularly displacing said diaphragm, said barometric device being hermetically sealed in an elastic capsule adapted to expand upon increase in operating altitude and the means coupling said diaphragm to said member including a rod whose displacement is controlled by said capsule, said capsule being interposed between said chamber and said distributor whereby expansion of said capsule shifts said diaphragm in the direction of displacement thereof with increasing suction in said chamber, said capsule being generally toroidal and said rod passing through said capsule.

7. The improvement defined in claim 2 wherein said means coupling said diaphragm to said member is a rod adapted to draw said member in one sense with increasing suction in said chamber, spring means connecting said capsule with said member increasing resistance to displacement of said member by said rod at relatively low altitudes and decreasing resistance to displacement of said member by said rod at relatively higher altitudes.

8. The improvement defined in claim 2, further comprising a rod connecting said capsule with said member for rotation of said member in response to expansion and contraction of said capsule.