US3183902A

US3183902A - Ignition apparatus

Info

Publication number: US3183902A
Application number: US194828A
Authority: US
Inventors: Wicklund Sven Erik
Original assignee: Atlas Copco AB
Current assignee: Atlas Copco AB
Priority date: 1962-05-15
Filing date: 1962-05-15
Publication date: 1965-05-18
Anticipated expiration: 1982-05-18

Description

y 1955 s. E. WICKLUND 3,183,902

IGNITION APPARATUS Filed May 15, 1962 3 Sheets-Sheet 1 Fig.

INVENTOR. (fix/0M BY W M y 1965 s. E. WICKLUND 3,183,902

IGNITION APPARATUS Filed May 15, 1962 3 Sheets-Sheet 2 A BY jay May 18, 1965 Filed May 15, 1962 5 Sheets-Sheet a S. E. WICKLUND IGNITION APPARATUS FIG. 4

SVEN

BY Au INVENTOR ERIK W/CKL UND M, ATTORNEY United States Patent 3,183,902 IGNITION APPARATUS Sven Erik Wicklund, Saltsjobaden, Sweden, assignor to Atlas Copco Aktieholag, Nacka, Sweden, a corporation of Sweden Filed May 15, 1962, Ser. No. 194,828 14 Claims. (Cl. 123-148) This invention relates to ignition apparatus for internal combustion engines having a casing and a crank shaft mounted to rotate in said casing. One object of the invention is to provide an ignition apparatus for internal combustion engines incorporated in combustion gas driven percussion tools, power saws, lawn mowers and other tools and apparatus in which it is desirable to have an easily interchangeable ignition apparatus in which the moving parts are well protected against dust and still easily available for inspection or adjustment. A further object of the invention is to provide an ignition apparatus which is cheap in manufacture and which is simple to assemble into the engine. A further object is to provide an ignition apparatus which enables a stabilisation of the speed of an internal combustion percussion tool operating on different loads. A still further object is to make possible accurate centering of the stationary pole members of an ignition apparatus relative, to the rotating magnetos so that a very small gap may be maintained between the stationary and the rotating pole members.

A still further object of the invention is to provide ample space for extra winding within the rotary magnetic field. Other features of the invention will be apparent from the following specification which describes by way of example one embodiment of an ignition apparatus according to the invention.

In the accompanying drawings FIG. 1 is a vertical longitudinal section through a portion of an internal combustion percussion tool showing the flywheel and ignition apparatus incorporated therein and associated parts. FIG. 2 is a view of the ignition apparatus and associated parts of the tool looking from the right in FIG. 1 with the ignition apparatus cover taken away, and FIG. 3 is a section on line III-III in FIG. 1. FIG. 4 is a diagrammatic showing of an embodiment of the invention in which there is shown both a spark coil and transformer.

The illustrated ignition apparatus is provided on an internal combustion percussion tool, one half of which only being illustrated. This tool has a casing 1 in which a crank shaft 2 is rotatably mounted and which is illustrated in FIG. 1 in a fragmentary sectional view only. The crank shaft is connected by a connecting rod 54 to a motor piston 55 reciprocable in a combustion cylinder 56 in casing 1. A combined opposed motion motor and hammer piston 57 is also reciprocable in the casing 1 under the action of combustion gases in cylinder 56 and compressed air or combustion gas acting in an auxiliary cylinder 58 in conventional manner. The piston 57 delivers blows to a working implement such as a drill steel or other tool. The crank shaft 2 has an extension 3 which carries a fan 4 and a flywheel 5 built together with a hub 44 and carrying a number of permanent magnets 6 disposed between pole members 7 of soft iron. The magnets and pole members are secured along the inside of a flange 8 formed on the flywheel 5. The magnets illustrated are of the peripheral type having peripherally spaced poles, but the magnets may also be of the radial type having radially spaced poles as is also conventional. The crank shaft extension 3 forms a trunnion 9 provided with an end portion 10. The trunnion 9 carries a stator housing 11 which is mounted on the trunnion 9 with a hub 12 forming a bearing so that the trunnion 9 may rotate in the hub 12 of the stator housing 11. The stator "ice housing 11 comprises a bottom plate 13 forming a partition between a space 45 confined within the flange 8 of the flywheel and a dust tight closed compartment 14 formed within the stator housing 11 and a cover 15 for said housing which is secured to the housing by suitable bolts. An inlet screen 16 is riveted to the stator housing 11 which is kept in a desired angular position by

adjustable linkage

17, 18 attached to the casing 1 by a pivot 46.

At the left side in FIG. 1 the stator housing carries an ignition coil 19 provided preferably with a primary and a secondary winding in conventional manner (not illustrated in detail) and with a core forming pole members 20 for cooperation with the magnets 6 and pole members 7. One end 21 of the primary winding is grounded to the stator housing and the other end is connected through a lead 22 to a screw 23 on the stator housing which is insulated from the stator housing and connected through a leave spring 24 with a breaker arm 25 swingably mounted on a pivot 26 insulated from the stator housing. The arm 25 in conventional manner carries a lug 27 of insulating material, which rides on a cam 28 driven by the crank shaft and adjustably mounted on the end portion 10 of the crank shaft trunnion 9. The arm 25 carries a contact point 29 cooperating with a contact point 30 carried by the housing 11 in leading contact with said housing. The cam 28 is rotatably adjustable on the end portion 10 of the crank shaft trunnion 9 and cooperates with a flyweight 31 which is pivotally carried by a pin 32 fitted on an arm 33 secured on the end portion 10 by means of a screw 34. The flyweight 31 engages a notch 35 with a dent 36 provided at the opposite end of the flyweight to the pin 32. A helical spring 37 encircles the pin 32 and engages the arm 33 and the flyweight 31 with its end portions so as to counteract the action by the centrifugal force on the weight 31 to turn the cam on the crank shaft. The flyweight acts to set the ignition point earlier at an increase of speed, which in a percussion tool of the type illustrated holds back the motor piston and reduces the output of the engine and the speed.

Within the stator housing an electrical condenser 38 is provided and mounted in a soft rubber sleeve 39 forming resilient lugs 47 held in grooves in four small posts 48 projecting from the bottom plate 13 of the stator housing. This mounting protects the condenser against damage by vibration. The condenser is connected at one end to the screw 23 through a lead 40 and grounded with the other end to a screw 41 by a lead 42, so that it is connected in parallel to the

breaker

25, 29, 30.

The secondary winding of the ignition coil is connected through a cable 43 with a spark plug 49 of the internal combustion engine 1 whereas the opposite end of the secondary winding is grounded. The screw 23 is connected to a grounded switch 50 by means of a lead 51 making it possible to stop the engine by short circuiting the breaker 25.

The position of the stator housing 11 on the casing 1 is adjustable by means of an arm 18 which may be set and arrested in various positions and which is connected with the stator housing 11 by a link 17. The arm 18 and link 17 also serve to electrically connect the stator housing 11 to the casing 1 so that the stator housing is well grounded. Adjustment of the arm 18 sets the ignition point which consequently can be varied by various settings of the arm 18.

The described ignition apparatus is provided partly within the fan 4 and vital parts of it are accessible upon removal of the cover 15. Removal of the cover 15 makes the compartment 14 accessible, and the cover 15 may be fastened to the housing 11 by suitable snap springs or other quick joints. It is obvious that the cover 15 effectively protects all the parts provided within the compartment 14 from dust, moisture and impurities, and, furthermore, the ignition coil 19 is disposed in a well protected position at the inside of the bottom plate 13, so that it can not be damaged when the cover 15 is removed. The provision of the ignition apparatus on the trunnion 9 comprises a simple manner of mounting the ignition apparatus in a position where it is easily available and removable and still in a manner which permits simple means for actuating the ignition apparatus from the crank shaft. 52 indicates further primary windings with core and pole members for generating electric current for light or other sundry purposes. 53 is a ground wire for the stator housmg.

The embodiment of the invention above described and illustrated in the drawings should only be considered as an example and may be modified in several different ways within the scope of the following claims. The coil means may, for instance, comprise a primary'winding and core cooperating directly with the rotating magnets and a transformer arranged on the casing separately from the rotating magnets and including a further primary winding and the secondary high tension winding. Such an arrangement is diagrammatically indicated in FIG. 4 in which the various above noted parts are indicated by the same reference numerals, except that a primary winding 191 is shown on core 2h, with an additional section of primary winding 192 provided outside the stator housing and having a secondary coil 193 within winding 192. Further, in connection with other internal combustion engines than the illustrated percussion motor it may sometimes be desirable to make the ignition point adjustment such that ignition is retarded at increased speed.

What I claim is:

1. A magneto ignition apparatus for an internal combustion engine having a casing and a crank shaft mounted to rotate in said casing, the combination which comprises magneto magnets mounted to be rotated by said crank shaft, a magneto housing journalled on and carried by said crank shaft and anchored to said casing against rotation with the crank shaft, ignition coil means including at least a primary winding, a core, and a secondary high tension winding disposed within the mag netic field of said magneto magnets, means for conducting magnetic flux from said magneto magnets at least through said primary winding, a circuit breaker having a fixed and a swingable breaker point mounted on and outside said magneto housing, cam means driven from said crank shaft cooperating with said breaker to move said breaker points in and out of contact with each other, an electric conduit leading from said coil means to said breaker, an electric condenser mounted outside said magneto housing and connected in parallel to said breaker, and an electric conduit leading from said secondary winding for supplying high tension current to a spark plug in the internal combustion engine.

2. An ignition apparatus according to claim 1, in which the circuit breaker and the cam actuating said breaker is mounted outside said housing, which is provided with a dust tight cover.

3. An ignition apparatus according to claim 1, in which said magneto housing is connected to the casing of said engine through adjustable means adapted to set the housing in various angular positions relative to the casing;

4. An ignition apparatus according to claim 1, in which the ignition coil means is disposed on the inside of said housing and the circuit breaker and breaker actuating cam means outside said housing.

5. An ignition apparatus according to claim 1, in which the condenser is mounted on said housing by means of shock absorbing elements.

6. An ignition apparatus according to claim 1 for an internal combustion engine having a cooling air fan, in which the rotating magneto magnets are built into the hub of the fan wheel.

7. An internal combustion engine comprising a casing, a crank shaft mounted to rotate in said casing and having an end portion journalled in the casing, a combustion cylinder in the casing, a motor piston reciprocable in said combustion cylinder and connected to said crank shaft, a hub carried by said end portion of the crank shaft, a set of magneto magnets carried by said hub, a fan comprising a set of vanes disposed radially outside said magnets, and a housing journalled on and carried by said end portion and anchored to said casing against rotation with the crank shaft and carrying ignition means associated with said magnets and arranged to supply high tension current to a spark plug in said combustion cylinder.

8. An internal combustion percussion tool comprising a casing, a crank shaft mounted to rotate in said casing, a combustion cylinder in the casing, a motor piston reciprocable in said combustion cylinder and connected to said crank shaft, a combined motor and hammer piston reciprocahle in said cylinder in opposed motion to said motor piston and driven solely by pressure fluid in said cylinder for delivering blows to a working implement, magneto ignition apparatus disposed upon and driven by said crank shaft, ignition means in the combustion cylinder connected to said ignition apparatus and arranged to be supplied with ignition current from said apparatus, and circuit breaker means in the ignition apparatus for changing the ignition point in response to changes of the speed of the combustion percussion tool.

9. In magneto apparatus of the character described for supplying intermittent spark current to the spark plug of an internal combustion engine having a casing and a crank shaft mounted for rotation therein, the combination which comprises an end portion of said crank shaft extending through said casing to the outside thereof and having a trunnion portion, a rotor mounted on said crank shaft for rotation therewith and outside said casing, a plurality of magneto magnets mounted around the periphery of said rotor, a housing wall mounted on said trunnion portion of said crank shaft and overlying said rotor, said wall being anchored to said casing against rotation with said crank shaft, an ignition coil mounted on said wall on the side thereof facing said rotor and disposed within the magnetic field of said magnets on said rotor for formingtherewith magneto current generating means, adjustable breaker point means mounted on the other side of said wall and operatively connected to said crank shaft through said wall for making and breaking movement therewith, and electric connections forming a circuit including said breaker means and said magneto coil for conducting current therefrom to said spark plug.

10. Apparatus as recited in claim 9 which also includes a condenser in said electric circuit connected in parallel with said breaker means and also mounted on the side of said wall opposite to that facing said rotor, and in which said breaker means and said condenser are enclosed within a removable dust cover mounted on said side of said wall.

11. Apparatus as recited in claim 9 which includes adjusting means connected to said housing wall and said engine casing for setting said wall at various position on said trunnion with relation to said casing to adjust the ignition point of said spark plug.

12. In magneto ignition apparatus of the character described for supplying a sparking current to the spark plug of an internal combustion engine having a casing and a crank shaft mounted to rotate in said casing and extending therethrough, the combination which comprises a trunnion mounted on the end of said crank shaft extending out of said casing, a rotor mounted on said crank shaft for rotation therewith and including a plurality of magneto magnets and cooling fan blades mounted around the periphery thereof, a stationary wall mounted on said trunnion outside said rotor and anchored against rotation with said crank shaft, an ignition coil mounted on said wall on the side thereof facing said rotor and disposed therewith forming said magneto, a set of breaker points, cam means driven by said crank shaft for moving said breaker points in and out of contact with each other, a condenser connected in parallel to said breaker points, said breaker points and cam means and condenser all being mounted on said stationary wall on the side thereof away from said rotor and said engine for easy access thereto, electric conduit means leading from said coil to said breaker points, electric conduit means leading from said ignition coil to said spark plug for supplying high tension current thereto, and a removable end cover mounted on said stationary wall for covering said breaker points and cam means and condenser.

13. In magneto ignition apparatus of the character described for a percussion tool driven by an internal combustion engine contained therein to supply an ignition sparking current to the spark plug of said internal combustion engine and having a casing and a crank shaft mounted to rotate in said casing and extending therethrough, the combination which comprises a trunnion mounted on the end of said crank shaft extending from said casing, a rotor mounted on said crank shaft for rotation therewith and including a plurality of magneto magnets mounted around the periphery thereof, a stationary wall mounted on said trunnion outside said rotor and anchored against rotation with said crank shaft, an ignition coil mounted on said wall on the side thereof facing said rotor and disposed with respect thereto to form a magneto, a set of breaker points, cam means mounted on and driven by said crank shaft for moving said breaker points in and out of contact with each other, means mounted on said crank shaft and connected to said cam means for changing the angular position of said cam means on said crank shaft in response to changes in the speed of rotation of said crank shaft, said breaker points and cam means and means for changing the angular position of said cam means all being mounted on said stationary wall on the side thereof away from said rotor and said engine for easy access thereto, electric conduit means forming a circuit including said coil and breaker points and spark plug for supplying high tension sparking current thereto, and a dust-tight readily removable cover mounted on said stationary wall and covering said breaker points and cam means and means for changing the angular position of said cam means.

14. Apparatus as recited in claim 13 in which said means for changing the angular position of said cam means with respect to said crank shaft includes a cam rotatably mounted on said crank shaft, an eccentric weight pivotally mounted on said crank shaft and including an indent engaging a notch in said cam, a spring disposed on said weight on the end thereof away from said indent for holding said weight against swinging movement whereby increased speed of rotation of said crank shaft causes said weight to swing by centrifugal force against said spring and move said cam from one angular position to another with respect to said crank shaft advancing the spark as the speed of rotation of said crank shaft increases and retarding the spark as the speed decreases.

References (Iited by the Examiner UNITED STATES PATENTS 1,501,486 7/24 Hunt et a1. 123-148 1,863,306 6/32 Hartzell 123-148 2,020,078 11/35 Nowosielski 123149 2,333,419 11/43 Fitch 123-7 2,538,534 1/51 Phelon 123-149 2,605,753 8/52 Madle 123146.5 2,686,501 8/54 McKelvy 123-46 2,688,101 8/54 Hersch et al 123148 FOREIGN PATENTS 8 84,431 7/53 Germany.

RICHARD B. WILKINSON, Primary Examiner.

Claims

1. A MAGNETO IGNITION, APPARATUS FOR AN INTERNAL COMBUSTION ENGINE HAVING A CASING AND A CRANK SHAFT MOUNTED TO ROTATE IN SAID CASING, THE COMBINATON WHICH COMPRISES MAGNETO MAGNETS MOUNTED TO BE ROTATED BY SAID CRANK SHAFT, A MAGNETO HOUSING JOURNALLED ON AND CARRIED BY SAID CRANK SHAFT ANCHORED TO SAID CASING AGAINST ROTATION WITH THE CRANK SHAFT, IGNITION COIL MEANS INCLUDING AT LEAST A PRIMARY WINDING, A CORE, AND A SECONDARY HIGH TENSION WINDING DISPOSED WITHIN THE MAGNETIC FIELD OF SAID MAGNETO MAGNETS, MEANS FOR CONDUCTING MAGNETIC FLUX FROM SAID MAGNETO MAGNETS AT LEAST THROUGH SAID PRIMARY WINDING, A CIRCUIT BREAKER HAVING A FIXED AND A SWINGABLE BREAKER POINT MOUNTED ON AND OUTSIDE SAID MAGNETO HOUSING, CAM MEANS DRIVEN FROM SAID CRANK SHAFT COOPERATING WITH SAID BREAKER TO MOVE SAID BREAKER POINTS IN AN OUT OF CONTACT WITH EACH OTHER, AN ELECTRIC CONDUIT LEADING FROM SAID COIL MEANS TO SAID BREAKER, AND ELECTRIC CONDENSER MOUNTED OUTSIDE SAID MAGNETO HOUSING AND CONNECTED IN PARALLEL TO SAID BREAKER, AND AN ELECTRIC CONDUIT LEADING FROM SAID SECONDARY WINDING FOR SUPPLYING HIGH TENSION CURRENT TO A SPARK PLUG IN THE INTERNAL COMBUSTION ENGINE.