US2451675A - Distributor - Google Patents

Description

oct. 19; 194s. K A, HARMON 2,451,675

DISTRIBUTOR Filed May 3, 1946 ey/V #M ATTORNEYS Patented Oct. 19, `1948v UNITED STATES PATENT OFFICE DISTRIBUTOR Kenneth A. Harmon, Longmeadow, Mass., assignor to Wico Electric Company, West Springfield, Mass., a corporation of Massachusetts Application May 3, 1946, Serial No. 667,069

(Cl. 20D- 24) 11 Claims.

This invention relates to improvements in distributors.

The invention has for one object to provide in a distributor an automatically adjustable, iioating mounting of the rotatable electrode on its driving member so that its face, which is successively moved into confronting relation with faces of the fixed electrodes of the distributor, may be positioned in parallelism with each lastnamed face as and when it confronts the same during its rotation.

The invention also has for an object to provide in a distributor, an improved mounting of the rotatable electrode for enabling compensation for wear of the electrodes to be automatically effected.

The invention, according to these objects, is capable of use in ignition systems where the movable electrode successively moved into close proximity to but does not actually engage the fixed electrodes. It provides for the maintenance of uniform gaps between the movable electrode and the fixed electrodes. It also provides compensation for wear of the electrodes, and hence provides for gaps that will not burn away due to sparking and become greater than the desired predetermined length.

The invention is also useful for use where contact between the movable electrode and each xed electrode is desired, as for example, in an ignition system of the type in which a capacitor is discharged through the primary of a spark plug ransformer to induce in the secondary a high tension, high frequency current to produce the ignition spark. The capacitor discharge is at relatively low tension and the timing of the discharges from the capacitor is effected by the distributor. The invention provides for accuracy of engagement between the movable and xed electrodes and also provides for accuracy in the timing of the discharges from the capacitor, as will hereinafter appear.

More particularly, the invention has for an object the provision in a distributor of a rotatable, electrode-carrying member, which is movable in the direction of its axis f rotation under spring pressure toward the member carrying the xed electrodes and which can also rock on such axis, and a stationary guide track on which ride a plurality of brushes xed on the rotatable member, for the purpose of positioning the outer end face of the movable electrode in the same transverse plane that includes the outer end faces of the xed electrodes, or in a plane parallel and closely adjacent to said transverse plane.

The invention will be disclosed with reference to the accompanying drawings, in which- Fig. 1 is a fragmentary elevational view of an ignition apparatus, the casing thereof being broken away to show a distributor embodying the invention;

Figs. 2 and 3 are cross on the line Fig. 4 is a of Fig. 3;

Figs. 5 and 6 are views taken similarly to Fig. 4 and showing modifications; and

Figs. '7 and 8 are diagrammatical views of the electrodes.

Referring to these drawings, there is shown in Fig. l a portion of the housing of an ignition apparatus, which may for example be constructed as disclosed in detail in Patent No. 2,433,715 of Sidney K. Smart and Allen L. Brownlee, dated December 30, 1947. Such housing includes casing elements l and 2 and these have been broken away in part to reveal the distributor which forms the subject matter of this invention. The cover 2 carries a support 3 for an annular ring 4, which carries the series of fixed electrodes of the distributor. The casing l carries a frame 5 having a stud 5 to rotatably support the moving element 7 of the distributor. There is also shown a driving pinion 8 rotatably supported from said frame.

As best shown in Fig. 2, the ring ll, which is constructed of suitable insulating material, carries a plurality of fixed electrodes 9. These are arranged around the axis of rotation of element l and, in this case, in a circular series coaxial with such axis. These electrodes preferably consist of rectangular strips of suitable hard metal, such as tungsten for example, which strips as shown in Fig. Li are set into the heads I of rivets Il, of which the electrodes are held shown, the outer end face of each electrode 9 lies ush with the face i2 of ring 4, which face forms a track for a purpose to later appear.

The rotatable distributor carries a plurality,

sectional views taken 2-2 and 3 3, respectively of Fig. l; sectional view taken on the line 4-4 element 'l (Fig. 3) preferably at least three, of brushes I3, which are suitably fixed thereto. These brushes may, for example, be of carbon graphite and they are adapted to ride on the track l2 (Fig. `4). The distributor element 'l has fixed thereto an electrode I4, which projects toward ring 4 and which is adapted to successively engage the electrodes 9. Electrode I4 is, or may be, constructed and mounted in the same way as rivet l5, which secures are the electrodes 9. The

electrode I4 to element 1, also secures it to one end of a spring i6. The other end of this spring bears on a suitable brush il, mounted in member 4 with its axis coinciding with that of the rotatable element 1. Current is conducted through brush i7 to spring I6 and contact i4 and distributed successively to the electrodes 9. The latter are connected, in any suitable way, to distribution wires, for example, as shown in said patent.

The rotatable element l (Fig. 1) is mounted to slide toward or away from lring 4 in the direction of the axis of rotation on a stud I3, which projects from a body i9, having thereon a gear 2l). The element 'i is loosely mounted on this stud so that it can rock to a certain extent. The body I9 contains a ball bearing 2 l the inner race of which is supported on the described stud 6. The gear 2li meshes with, and is driven by, the pinion 8. A spring 22 acts between the gear 20 and element 'i to urge the latter toward ring 4. A snap ring 23 on stud I8 limits the outward movement of the element by the spring. Two pins 2d, xed in the body I9, project into holes in element 1 and serve to drive the element and yet allow it to slide in the direction of its axis and rock, as and when required.

The rotatable element 'i can wobble on its driving member. The brushes I3, when engaged with track l2 as shown in Fig. 4, so position the element i that the outer end face of its electrode l is located in a transverse plane which includes the outer end faces of all the fixed electrodes 9. In the particular form shown, the .outer end faces of the several brushes i3 and the outer end face of electrode i4 are finished so that they lie in the same plane, or substantially so, and the outer end faces of the xed electrodes are nished to lie in the same plane as the track l2, or substantially so. Thus, the desired result is obtained. The engagement of the brushes at three points insures that the disk 'l is maintained in a plane parallel with the track l2 and that the outer end face of electrode i4 is maintained in the same plane as that which includes the outer end faces of all the electrodes 9.

It is not necessarily essential that the fixed electrodes 9 have their outer end faces located in the plane of the track i2. For example, the electrodes 9', shown in Fig. 5, project beyond the outer end face of the annular ring 4', in which they are supported, and the outer end faces of all these electrodes 9 lie in a common plane which is spaced from but parallel with a brass track l2', mounted in member 4. It is desirable in this case, to have the brushes i3 located radially beyond the electrodes 9 and beyond the cooperating movable electrode l on the rotatable distributor element 'E'. Other things being equal, the greater the radial spacing of the brushes from the axis of rotation, the more accurately will the end face of the rotatable electrode I4' be held in the desired |position. And where the electrodes 9' protrude from their support, such as 9', it is desirable to avoid impingement of the rotating electrode on any of the fixed electrodes. There is a tendency for the leading edge of the movable electrode to erode, due to the electrical discharge, which occurs under some conditions as will later be explained, when the movable electrode ap proaches closely to a fixed electrode. The result of such erosion is to cause the leading edge of the movable electrode and the edges of each xed electrode which it approaches to become rounded. This condition is shown in Fig. 7. If such edges i of the electrodes are rounded, the movable electrode will readily ride up onto each xed electrode 9 and not cause damage in case the brushes for any reason fail to hold the movable electrode exactly in the proper plane.

Where the electrodes, such as 9, are inset into their supporting member, such `as 4, it is desirable to have recesses adjacent each fixed electrode, and especially adjacent that edge of each which l0 the electrode l leaves when breaking engagement. Otherwise, the movable electrode will wipe off the fine metallic dust, due to electrode wear, and deposit it upon the outer end face of the insulating member In time, a conducting track between successive contacts of the series might be established in this manner. The recesses 25, shown in Fig. 2, serve to receive the metal particles and prevent them from being carried along to damage the member d. The use of projecting electrodes 9', such as are shown in Fig. 5, is another way of avoiding trouble from the `metal particles which are worn off the electrodes due to their mechanical engagement. ,A It is not necessary for all purposes to have physical contact between the relatively movable electrodes. Fig. G shows a distributor in which there is a gap between the movable electrode i4 and each iixed electrode 9, when the movable electrode is successively brought into confronting l relation with the fixed electrodes. Fig. 6 is otherwise exactly like Fig. 4 and corresponding parts in these two views have been given the same reference numerals.

When the distributor is used in connection with an ignition system in which a capacitor is discharged through the primary of a spark plug transformer to induce in the secondary, a high tension, high frequency current to produce the i ignition spark, the only electrical discharge occurs on or just slightly before engagement of the electrodes. This electrical discharge is from a capacitor and the latter is completely discharged as soon as the movable electrode engages a fixed electrode. It follows that there can be no discharge between a iixed electrode and the trailing edge of the movable electrode. Whether the discharge occurs before the engagement of a fixed electrode by the leading edge of the movable electrode depends upon conditions. The discharge at relatively low tension, say 1500 volts. Hence,

the spark cannot jump yanything other than a very short gap. Whether a spark jumps from the leading edge of the movable electrode i4 to the adjacent edge of a fixed electrode 9 as the former approaches the latter depends for one thing on the speed of approach. If this speed is in excess of the rate of ionization of the air, as it appears to be is at normal engine speeds, no spark will occur providing that atmospheric pressure is substantially normal. But when the distributor is operating under sub-normal pressures, as `at high altitudes, the rate of ionization may exceed the electrode speed even at full engine speed and cause a spark. Hence, a :spark may at some times occur between the movable electrode and the xed electrodes which it approaches and, when sparking does occur, the tendency is to cause the leading edge of the movable Yelectrode and those edges of the fixed electrodes.

that are approached by such leading edge, to become rounded, as shown in Vsomewhat exaggerated form in Fig. '7.

Continued erosion, unless compensated for, will cause a change in the timing of the spark. More and more of the outer face of each electrode will be eroded until a condition, such as shown in Fig. 8 for example, exists. Then the movable electrode iii will have to move farther before it approaches closely enough to a fixed electrode 9 to discharge the capacitor and the spark will occur later in the engine cycle, as will be clear from a comparison of Fig. 8 with Fig. 7. The wear due to mechanical engagement of the electrodes tends to offset the wear due to electrical discharge in that the outer faces are being continually worn down and this tends to keep the engaging edges substantially flat so that they engage as planned, as for example, as indicated in Fig. '7. It is important to keep such edges thus conditioned in order to maintain accuracy of timing of the electrical discharges-from the capacitor. The electrodes may be initially rounded as shown in Fig. '7.

An ideal condition would be to have the sum of the Wear of the movable electrode and the Wear of a xed electrode equal the sum of the wear of a brush and the wear of the track. However, the amount of wear is dependent on so many factors that it is not possible to specify materials, the use of which will yield or closely approach the ideal condition in all cases. For example, the wear on the movable electrode increases in direct proportion to the number of fixed electrodes. So also, the Wear on each brush will diminish as the number of brushes increase.

The Wear on the electrodes depends on their dimensions and the material of which they are made and the amount of erosion due to electrical discharges. And the wear of the brushes depends on their dimensions and material of which they are made. The best that can be done is to choose the materials to t each particular case and attempt in this Way to balance the wear. Balance of Wear is more important Where the fixed electrodes project beyond their support, as in Fig. 5, than it is with the Fig. 4 form. The best arrangement now known to me for the Fig. 5 form, where there are four fixed electrodes, is to make the fixed and movable electrodes of tungsten and of the dimensions shown (the iigure is full size), and to use three brushes of carbon graphite of the size shown and riding on a track of brass. Since it is not feasible to secure exactly balanced Wear, it is best to have the brushes and track wear somewhat faster than the electrodes because this insures that the electrodes cannot wear out of engagement and that they may be worn down by mechanical abrasion to keep the contacting surfaces bright and clean and flat and to compensate for the effects of erosion.

While it is desirable, where the distributor is used in an ignition system, of the described capacitor type, to have contact between the movable and fixed electrodes, the invention is :nevertheless useful where this ideal condition is not exactly maintained. For example, if because of imperfections due to manufacturing diiculties, the ideal condition is not always realized, the invention will nevertheless maintain the confronting surfaces of the relatively movable electrodes so close together that the capacitor will be discharged. For example, if such surfaces be spaced apart by .003 inch, this is close enough so that the capacitor with a voltage of say 1000 will discharge.

The invention thus provides a distributor with an improved mounting of the movable electrode so that it may be adjustably moved automatically and as necessary to cause its surface, which confronts cooperating surfaces of the xed electrodes, to be moved into parallelism with the last-named surfaces as it successively confronts the latter during its rotation.

I claim:

1. ln a distributor, a rotatable driving member, a. plurality of ilxed electrodes disposed around the axis of revolution of said member and each having an exposed face, an element rotatably driven by said member, an electrode xed to said element and having a face adapted to successively move into confronting relation with each of the first-named faces during rotation of said member, said element being mounted to oat on its driving member With freedom to be adjustably moved as may be necessary toV enable said end faceV of the rotatable electrode to freely move into parallelism with each of the first-named faces as it confronts the same, axed track adjacent the fixed electrodes, a plurality of brushes fixed to said element and riding on said track, and means for adjustably moving said element to press said brushes against said track, Whereby to cause said face of the rotatable electrode as it moves into confronting relation with each of the first-named faces to be positioned in parallelism therewith.

2. In a distributor, a rotatable driving member, a plurality of xed electrodes disposed around the axis of revolution of said member and each having an exposed face, an element rotatably driven by said member, an electrode xed to said element and having a face adapted to successively move into confronting relation with each of the first-named faces during rotation of said member, said element being mounted to float on its driving member with freedom to be adjustably moved as may be necessary to enable said end face of the rotatable electrode to freely move into parallelism with each of the first-named faces as it confronts the same, a fixed track adjacent the fixed electrodes, three brushes fixed to said element and riding on said track, and means for adjustably moving said element to press said brushes against said track, whereby to cause said face of the rotatable electrode as it moves into confronting relation with each of the first-named faces to be positioned in parallelism therewith.

3. In a distributor, a rotatable driving member, a plurality of xed electrodes disposed around the axis of revolution of said member and each having an exposed face, an element rotatably driven by said member, an electrode fixed to said element and having a face adapted to successively engage and wipe across the firstnamed faces, said element being mounted to float on said member with freedom to be adjustably moved as necessary to enable said face of the rotatable electrode to be positioned to successively engage the first-named faces in parallelism, a fixed track adjacent the xed electrodes, a plurality of brushes xed to said element and riding on said track, and means for moving said element topress said brushes against the track, whereby to position said face of the rotatable electrode for engagement successively and in parallelism with the first-named faces.

4. In a distributor, a rotatable driving member, a plurality of xed electrodes disposed around the axis of revolution of said member and each having an exposed face, an element rotatably driven by said member, an electrode xed to said element and having a facefadapted to successively engage and 'wipe across the rst-named faces,

said element being mounted to Viioat on said mem ber with freedom to be adjustably moved as necessary to enable said face of the rotatable electr-ode to be positioned to successively engage the faces of the xed electrodes in parallelism, a xed track adjacent the fixed electrodes,`three brushes fixed to said element and riding on said track, and means for movingsaid element to press said brushes against the track, whereby to position said face of the rotatable electrode for engagement successively and in parallelism with the faces of the fixed electrodes.

5. In a distributor,l a rotatable driving member, an element mounted on said member to rotate therewith and to move in theV direction of the axis of rotation thereof, yieldable means tending to move said element axially away from said member, a stationary support having a plurality of electrodes disposed around said axis and extending toward said element, an electrode on.

said element projecting toward said support and having an end face adapted to successively engage the end face of the electrodes of said series as the element rotates, said support having a circular track, and a plurality of brushes fixed to said element and caused by said yieldable means to press against said track and maintain the contacting face of the electrode on said element in the same plane which includes the contacting faces of the fixed electrodes.

6. In a distributor, a rotatable driving member, a distributor element mounted on said member to rotate therewith and to move in the direction of the axis of rotation thereof and capable of rocking with respect to a plane at right angles to said axis, an electrode fixed to said element and projecting outwardly therefrom in a direction parallel to said axis, a stationary support having a circular track disposed in a plane at right angles to said axis, a plurality of electrodes fixed to said'A support and disposed around said axis, said fixed electrodes extending toward said element and adapted to be successively engaged by the rst-named electrode on rotation of the element, a plurality of brushes fixed to said element and riding on said track, and spring means for moving said element away from its driving member and pressing said brushes against the track to position the contacting face of the rotatable electrode in the plane in which the contacting face of each electrode lies.

7. In a distributor, a rotatable driving member, an element mounted on said member to rotate therewith and to move in the direction of the axis of rotation thereof, an electrode fixed to said element and projecting outwardly therefrom in a direction parallel to said axis, a stationary support having a circular track disposed in a plane at right angles to said axis, a plurality of electrodes xed to said support and disposed around said axis, said fixed electrodes extending toward said element and adapted to be successively engaged by the first-named electrode on rotation of the element, at least three brushes fixed to said element and riding on said track, and spring means for moving said element outwardly from its driving member and pressing said brushes against the track to position the contacting face of the rotatable electrode in the plane in which the contacting face of each fixed electrode lies.

8. In a distributor, a rotatable driving member having a stud projecting therefrom in the direction of the axis ofrotation thereof, a distributor element loosely mounted on saidstud and free to slide back and forth and rock thereon, spring means to press the element outwardly, means to limit the outward movement of the element, a connection between said element and member to cause them to rotate together, an electrode fixed to and projecting outwardly from the `ele-nient in a direction parallel to said axis, a stationary support having a circular track located in a plane at right angles to said axis, a plurality of fixed electrodes disposed around said axis and having their outer faces located in a plane at right angles to said axis, and brushes fixed to said element and moved by said spring against said track to position said element so that the outer face of the rotatable electrode lies in the last-named plane.

9. In a distributor, a rotatable driving member, an element mounted on said member to rotate therewith and to move in the direction of the axis of rotation thereof, an electrode xed to said element and projecting outwardly therefrom in a direction parallel to said axis, a stationary support having a circular track disposed in plane at right angles to said axis, a, plurality of electrodes fixed to said support and disposed around said axis, said fixed electrodes extending toward said element and adapted to be successively engaged by the first-named electrode on rotation of the element, at least three brushes fixed to said element and riding on said track, each of said brushes located at a greater radial distance from the axis of rotation of said element than the electrode thereon, and spring means for pressing said element outwardly from its driving member to press said brushes against the track and position the outer face of the rotatable elec-v trode in the plane in which the outer face of each fixed electrode lies.

10. In a distributor, a rotatable driving member, an element mounted on said member to rotate therewith and to move in the direction of the axis of rotation thereof, an electrode fixed to said element and projecting outwardly therefrom in a direction parallel to said axis, a stationary support of insulating material having a circular track disposed in a plane at right angles to said axis, a plurality of electrodes fixed to said support and disposed around said axis, said fixed electrodes extending toward said element and adapted to be successively engaged by the .firstnarned electrode on rotation of the element, the outer faces of the fixed electrodes lying flush with the outer face of said support, at least three brushes fixed to said element and riding on said track, each of said brushes located at a less radial distance from the axis of rotation of the element than the electrode thereon, and spring means for moving said element outwardly from its driving member and pressing said brushes against the track to position the outer face of the rotatable electrode in the plane in which the outer face of each fixed electrode lies.

11. In a distributor, a rotatable driving member, an element mounted on said member tol rotate therewith and to move in the direction of the axis of rotation thereof, an electrode fixed to said element and projecting outwardly therefrom in a direction parallel to said axis, a stationary support of insulating material having a circular track disposed in a plane at right angles to said axis, a plurality of electrodes xed to said support and disposed around said axis, said xed electrodes extending toward said element and adapted to be successively engaged by the rotatable electrode on rotation of the element, said KENNETH A. HARMON.

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

UNITED STATES PATENTS Number Name Date 1,429,037 Larison Apr. 29, 1934 1.470,230 Williams Oct. 9, 1923

Images