US2595690A

US2595690A - Engine ignition timer

Info

Publication number: US2595690A
Application number: US24817A
Authority: US
Inventors: Montifret Maurice
Original assignee: Ducellier et Cie
Current assignee: Ducellier et Cie
Priority date: 1943-07-20
Filing date: 1948-05-03
Publication date: 1952-05-06
Anticipated expiration: 1969-05-06

Description

y 6, 1952 M. MONTIFRET 2,595,690

' ENGINE IGNITION TIMER Filed May s. 1948 2 sHEE s-smm 1 May 6, 1952 M. MONTIFRET 2,595,690

ENGINE IGNITION TIMER Filed May 5, 1948 2 SHEETSSHEET 2 a/wfa- Patented May 6, 1952 ENGINE IGNITION TIMER Maurice Montifret, Pari s, France, assignor to Societe Anonyme des Etablissements Ducellier,

Paris, France Application May 3, 1948, Serial No. 24,817 In France July 20, 1943 A 1 Claim. 1

This invention relates to improvements in ignition timers in whichth'e circuit through the primary coil is broken with the aid of a rotary cam cooperating with a follower carried by a rocking arm, the free end of which carries the movable contact stud which normally is resiliently pressed against the fixed contact stud and which is periodically moved away from the same by the bosses on the cam to generate the spark.

It is well known that the timing of the spark, or ignition lead, must be adjusted to correspond with engine Working conditions, and particularly the R. P. M., the intake vacuum, the fuel used, and so on.

This invention provides a device whereby this requirement can be fully met. The device oomprises a movable follower which can be regulated automatically or adjusted by hand as regards its position with respect to the cam in dependency on one or several engine working conditions, contingently through the medium of a stroke-reducing mechanism.

In a preferred embodiment of the invention the follower is movable lengthwise of its supporting arm.

It may also be mounted for angular adjustment about any desired axis, for instance that of the timing device.

With the last-mentioned arrangement the timing of the spark can be varied quite simply and the inconveniences connected with the movable contacts in timers of the prior art are avoided.

Where the follower is movable lengthwise of the arm it is preferably arranged at one end of a spring adapted to permanently press the back portion of the follower against the web portion of the normal U-shaped arm, the flanges of which serve to guide the follower in its longitudinal displacements.

Contingently, that portion of the arm web which is engaged by the follower may be formed with a slight arcuate depression in order that the lift of the movable contact stud will remain substantially constant irrespective of the position of the follower lengthwise of the arm.

The position of the follower may be adjusted through stroke-reducing transmission means, for example by pivoting the follower on a link, the movable end of which is connected operatively with the control member.

Two embodiments of a timer adapted to control the timing of the ignition in an internal combustion engine in dependency on the variations on the suction side of the engine will be described hereinafter as examples only of the present invention.

In the drawings:

Figure 1 is a plan view of one embodiment of the invention;

Figure 2 is a diagrammatic vertical section;

Figure 3 is an enlarged partly sectional plan view of the contact stud carrying arm and related parts; .1

Figure 4 is the corresponding plan view Figure 5 is a sectional view of a detail; and

Figure 6 is a plan View of a second embodiment of the invention.

The timer illustrated in Figs. 1 to 5 comprises a casing I in which a cam 3 is keyed on a vertical shaft .2. An arm 4 is mounted for swinging motion on a pin 5. An insulating follower i is continuously urged into engagement with the cam 3 by a spring 6. Secured to the free end of the arm 4 is a contact stud 8 which cooperates with the fixed contact stud 9. Either contact stud is connected conductively with the primary winding of an ignition coil in a manner known per se.

In the embodiment illustrated in Figs. 1 to 5 the follower I is secured to the free end of a resilient strip I I by which its rounded back end Ia. forming a boss is pressed against the web portion of the U-shaped arm 4 the flanges of which serve as guides for the follower.

In the embodiment illustrated in Fig. 6 the follower 1 is pivoted on a pivot pin I8 carried by a crank link I9 swingably mounted on a pin 2E! and. to the free end of which the actuating rod [5 is fulcrumed by pin 2|.

Arranged within a chamber I2, which is connected through a pipe I3 with the intake of the engine, is a flexible membrane I4 to the center of which rod I5 is secured which is urged by a spring I 6 in a direction contrary to the action of the vacuum upon membrane I4. The resilient strip I I is secured to the other end of the rod I 5, with the result that the position of the follower 1 is dependent on the position of the membrane I 4 and consequently on the vacuum prevailing in the engine intake pipe.

When the cam shaft 2 is revolved in the direction shown by the arrow in Fig. 1 any displacement of the follower 1 towards the left due to an increase in the vacuum will result in an increase in the lead to the ignition.

In view of the fact that a strictly rectilinear displacement of the follower will alter the lift of contact stud 8 with respect to contact stud 9, it is advisable to provide an. arcuate recess or depression in that portion I1 of the arm 4 which cooperates with the boss 1a formed at the rear of the follower 1, whereby the above mentioned inconvenience is avoided.

In the arrangement described, the follower which is the only member to be displaced can be very light in weight; its inertia is consequently very low, so that a very quick response is obtained, all the more as friction between the rounded back portion la of the follower and the web of the arm is quite low.

In the embodiment of Fig. 6 a fixed contact 9 is secured to the casing l. A pawl H) has one end thereof pivoted upon a fixed axis of oscillation and the other end thereof has a movable contact 8 secured thereto for cooperation with the fixed contact 9. The pawl I!) also has a finger thereon as seen in this figure. The follower 1 which is pivotally mounted at 18 has one end thereof formed as a hammer and this hammer is in frictional contact with the cam 3 and the finger on the pawl. Upon actuation of the rod I5 by the flexible member M, the crank link I!) swings around pin 20 and consequently the follower 1 is moved in an obvious manner to change its position of contact between the cam 3 and the finger of the pawl I0. Thus it will be seen that the instant of ignition contact is regulated responsive to the engine operating conditions in a manner analogous to that described with relation to Figs. 1 to 5 of the drawings.

The device may be mounted as such on an existing timer in which the lead to the ignition is controlled in dependency for example on the engine R. P. M.

The control member through which the fol lower is influenced in dependency on the working conditions in the engine may consist of a piston movable in a cylinder that will perform the same function as the vacuum-responsive membrane. A coil or any equivalent spring may be substituted for the leaf spring that acts upon the stud-carrying arm and also the follower may be moved by means other than by a resilient strip. None of these obvious modifications need be described and illustrated.

The device according to the invention may be used for controlling the lead to the ignition by hand or in dependency on any desired engine working condition other than the vacuum prevailing in the engine intake pipe.

What I claim as my invention and desire to secure by Letters Patent is: i

In a timer for battery-ignited combustion engines the combination comprising a casing, a member associated with said casing responsive to engine operating conditions, a rotatable shaft driven by said engine, a cam secured to said shaft, a pawl having one end pivoted upon a fixed axis of oscillation and the other end thereof forming a movable contact, a fixed contact upon said casing opposite said movable contact, means for regulating the instant of ignition contact consisting of a pivotally mounted follower having one end thereof in the form of a hammer in frictional contact with the cam and a finger of the pawl, a crank link pivoted at one end upon said casing having towards its middle a pivot pin and an actuating rod having one end pivoted at the free end of said crank link and whose other end is connected to said member responsive to engine operating conditions.

MAURICE MONTIFRET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,812,647 French June 30, 1931 1,847,761 Hittle Mar. 1, 1932 2,066,640 Melcher Jan. 5, 1937 2,348,236 Arthur May 9, 1944 FOREIGN PATENTS Number Country Date 463,463 Great Britain Mar. 31, 1937 628,206 Great Britain Aug. 24, 1949