US3186397A - Electrical apparatus - Google Patents

Description

D. C. LOUDON ELECTRICAL APPARATUS Original Filed Jan. 12, 1962 June 1, 1965 l" INVENTOR.

DONALD C. LOUDON BY gf flww ATTOR EYS United States Patent 3,186,397 ELECTRICAL APPARATUS Ronald C. London, Sidney, N.Y., assignor to The Bendix Corporation, Sidney, N.Y., a corporation of Delaware Continuation of appiication Ser. No. 165,908, Jan. 12, 1962. This application June 19, 1964, Ser. No. 386,474 22 Claims. (Cl. 123-148) This application is a continuation of application Serial No. 165,908, filed January 12, 1962, for Electrical Apparatus, now abandoned.

This invention relates to electrical apparatus, and more particularly relates to a system for generating timed electrical pulses. The apparatus of the invention may be employed to advantage, for example, in an ignition system for an internal combustion engine.

The invention has among its objects the provision of a novel electrical pulse generating system.

A further object of the invention resides in the provision of a pulse generating system which does not require the use of a mechanically operated breaker or contacts.

Another object of the invention lies in the provision of a breakerless pulse generating system which is particularly well adapted for use in ignition systems for internal combustion engines.

Yet another object of the invention lies in the provision, in a specific preferred embodiment of pulse generating apparatus in accordance with the invention, of novel means for selectively retarding the timing of generated pulses, as for retarding the spark ignition of an internal combustion engine.

Still another object of the invention lies in the provision, in a specific preferred embodiment of pulse generating apparatus in accordance with the invention employing a triggered solid state switching device, of novel circuit means for erasing the trigger signal from the switching device between pulses.

A still further object of the invention lies in the provision of a pulse generating system which is particularly characterized by its simplicity, its economy of manufacture and maintenance, and its long life.

The above and further objects and novel features of the invention will more fully appear from the following description when the same is read in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for the purpose of illustration only, and is not intended as a definition of the limits of the invention.

The sole figure of the drawing is a schematic Wiring diagram of an illustrative preferred embodiment of the pulse generating apparatus in accordance with the invention, such apparatus being shown employed for providing ignition spark discharges for an internal combustion engine.

As above indicated, the apparatus of the present invention is particularly advantageous when employed to supply ignition spark discharges for an internal combustion engine. It is to be understood, however, that the apparatus of the invention is capable of a number of different applications wherein timed electrical pulses or discharges are required. The apparatus is particularly characterized by the fact that it requires no mechanically operated breaker or contacts and thus is free from the maintenance problems which the use of such breakers entails. In the illustrative embodiment, the apparatus employs a magneto as its primary source of power, the apparatus including pulse triggering means in the form of a rotating triggering wheel and a picieup coil. The switching functions in the system are performed by solid state switching devices which have no moving parts. As a consequence, the apparatus of the invention will operate for long periods without the necessity of attention.

Turning now to the drawing, the illustrative system includes a power supplying and triggering portion, generally designated 10, and an energy storage unit, generally designated 11. Power stored in circuit portion 11 is discharged into a circuit including a distributor 12 from which the discharge is led to one or more output circuits 14, 14'.

The portion of the system includes a magneto schematically shown at 15, the magneto having a rotor 16 carrying a plurality of angularly spaced magnetic pole pieces 17. Rotor 16 is shown associated with a magneto field coil 19 which has a center tap 23 connected to ground, as shown. The opposite ends of coil 19 are connected to an output wire 22 by rectifying diodes 20 and 21, respectively. Thus the magneto functions to deliver direct current to the main supply wire 24 to which wire 22 is connected.

Wire 24 may be selectively connected to ground 27 by an ignition switch provided with a movable contactor 26. When switch 25 is operated to disconnect wire 24 from ground, the magneto 15 becomes operative. To supplement the output of the magneto at low or cranking speeds, there is provided a starting vibrator assembly .29 which may be selectively operated to deliver a substantial amount of direct current energy to wire 24.

A battery 31 is provided, the negative terminal of the battery being connected to ground by wire 32. The positive terminal of battery 31 is connected by a wire 34 to a starter solenoid 36 through a starter switch 37. Solenoid 36 is connected to ground at 39. When switch 37 is closed, solenoid 36 functions to connect wire 40 connected between vibrator 29 and the solenoid to the positive terminal of battery 31. Thereupon the vibrator assembly delivers its direct current output through wire 30 into wire 24. i

Wire 24 extends intoenergy storage unit 11 where it is connected to a first, condenser charging circuit and to a second, condenser discharging circuit. A storage condenser 41 of substantial capacity, for example, 2.00 mid, has one terminal thereof connected to wire 24 through a wire 42. The other terminal of condenser 41 is connected by a wire 44 to the center terminal 45 of the distributor 12. Such distributor has a rotatable central distributing arm 46 which is driven in synchronism with the engine. Arm 46 sequentia1ly cooperates with a plurality of spaced electrically conducting segments 47, each of the segments being connected to its respective output circuit 14, 14.

Output circuit 14 includes a wire 49 leading from its respective segment 47 and connected to one end of the primary winding 50 of a voltage step-up transformer 51. Transformer 51 has a secondary winding 52 connected at one end to the other terminal of primary 50 and to ground. The second end of secondary 52 is connected by a wire 54 to the first electrode 55 of an ignitcr gap such as a spark plug. The second electrode 56 of the igniter gap is connected to ground by a wire 57.

it will thus be seen that when the center arm 46 makes contact with a given segment 47 the charging circuit for condenser 41 is established from wire 24 through the condenser to wire 44 through the distributor through the primary winding of the respective step-up transformer and to ground. The characteristics of the magneto, of the starting vibrator assembly 29, if it is used, and of the charging circuit are such that condenser 41 becomes fully charged soon after the central arm of the distributor enters into contact with each segment 47 of the distributor.

Connected in shunt across storage condenser 41 is a condenesr discharging circuit. Such latter circuit includes the wire 24 beyond wire 42, and a solid state switching device 5& interposed between wire 24 and ground at 48, the switching device operating to discharge the condenser after it has been fully charged. Device 59 may be a silicon controlled rectifier having an anode 60 connected Patented June 1, 1965 amass? Q to wire 24, a cathode 61 connected to a portion of the discharge circuit leading to ground, and a triggering means or gate 62 by means of which device $9 is selectively made conductive. Cathode 61 is connected by wires 64 and 65, a breakdown or Zener diode 66 and a wire 67 to the further wire 69 which is connected to ground 48. Diode 66, which has a low breakdown voltage, is a part of a triggering signal erasing circuit to be described. The discharge of condenser 41 is completed through ground, primary 56 of step-up transformer 41, wire 49, segment 47, distributor rotor 4-6, and wire 44. The rush of current through primary 58 upon discharge of condenser 41 induces a high voltage in secondary 52 of the transformer, thereby producing a spark discharge between electrodes 55 and 56.

Switching device a is triggered by a triggering mechanism generally designated 70 so as to produce a succession of timed spark discharges at the spark gap. Device 74 includes a pickup coil 71 having a core 72. in the form of a permanent magnet. Rotating close to coil 7?. is a triggering wheel 74 having a plurality of angularly spaced vanes '75 on its periphery. Wheel 74 is driven in synchronism with rotor 16 of the magneto as by a driving means schematically shown at 7d. Means 76 in the illustrative embodiment includes a speed increasing gear device indicated at 77 so that the wheel 74 rotates at a speed faster than rotor 16. The speeds and angular relationships of triggering wheel 74 and of distributor arm 46 are maintained constant by the driving mechanism 76 and by a driving mechanism 73 by means of which distributor rotor 45 is driven. The parts of the pickup device are so related that a vane 75 passes through the magnetic field of core 72 at each time that a spark discharge is required for the engine, the distributor arm 46 then being in contact with the corresponding segment 47.

At each passage of a vane 75 past the pickup coil 71, a triggering voltage pulse is produced in the coil. One end of coil 71 is connected by a wire 79 which extends to one or" the contacts of a normally closed pair of contacts 8t as shown. The other of such contacts is connected to ground at 34. The other end of coil 71 is connected by a wire 87 to a further wire 89 extending to the triggering means or gate 62 of switching device 5%. Wire 87 extends to wire 67, there being interposed in wire 87 beyond wire 89 a Zener or breakdown diode 8t}. Zener diode 90 may have a rating, for example, of 5.0 volts. Connected in shunt with diode 99 is a resistor E91 which may have, for example, a resistance value of 1.8K ohms.

It will be seen that at each cycle of the spark discharge system the storage condenser 41 becomes charged and then, while distributor arm 4-6 is in contact with the same segment 47, a triggering pulse generated by triggering means 7% causes switching means 59 to discharge. Switching means 5? may be a device of the type known either as a silicon controlled rectifier or a silicon controlled switch. In the illustrative embodiment, device is a silicon controlled switch of such character that the anode voltage must swing negative for a period in excess of 5.0 p.550. for the switching device to regain control and to turn The anode voltage in the disclosed circuit swings negative for a period in excess of such required time, and so such condition is met. There is, however, a tendency for the triggering pulse developed by the pickup 7d at higher speeds to keep the switch turned on. There is thus employed in the illustrative circuit a trigger eraser circuit which makes the turning oil of the switching device 59 independent of the triggering pulse duration.

The components of such erasing circuit are the abovedescribed Zener diode 6d, a resistor connected in shunt with such diode and a condenser 92 also connected in shunt with the diode. Resistor 94 may have, for example, a resistance of SR ohms; condenser 92; may have, for example, a capacity of 0.22 mfd. During the dis charge of storage condenser 41, a positive voltage is placed on condenser 92, the magnitude of such positive voltage being governed by the breakdown voltage of diode 66. The magnitude of this voltage is in excess of the positive trigger voltage and therefore removes the effect of the triggering pulse on the control switch 59, thereby allowing it to turn oil. The resistor 94 bleeds oil the charge on condenser 92 so that the next triggering pulse will again trigger the switching device 59.

The illustrative ignition system includes means whereby the spark may be selectively advanced, if desired. Such spark advancing means includes a small condenser 85, having a capacity on the order of .01 mid, which is connected at one terminal to wire 79 and at the other terminal to ground at $5. When wire 79 is connected directly to ground 84 by the closed contacts St}, the spark discharges will occur at a first predetermined time in the engine cycle. When, however, contacts 86 are opened and wire 7? is connected to ground only through condenser the spark discharge takes place at a predeterminer earlier time in each engine cycle.

Contacts 8%, which are part of a relay generally designated 82, may be selectively opened by energizing the coil 31 of such relay. The relay coil may be energized by the battery 31, the positive terminal of the battery being connected by a wire 95 through a switch 97 having a movable contactor 96. The fixed contact of switch 97 is connected to relay coil 81 by wire $9, as shown.

The system shown includes a Zener diode 1% which is interposed in wire Till extending between wire 24 and ground at 1132. Diode ltlll may, for example, have a breakdown voltage of 200 volts and a rating of 50 watts. Such diode, which is connected in shunt with the switching device 59, protects such device in the event that the primary winding 5% of transformer 51 should develop an open circuit.

The ignition system shown is suitable, for example, for use with an 8 cylinder, 4 cycle engine, the magneto and distributor rotors being connected to the engine to run at one-half crank shaft speed. The system shown, however, when suitably modified, may be employed with a great variety of internal combustion engines of different types and numbers of cylinders. The system of the invention is particularly advantageous because Of its freedom from mechanically operated breaker contacts. The system thus requires very little maintenance over long periods of use. The circuit of the invention is also stable under wide variations of temperature, producing sati factory results, for example, over a temperature range of 30 F. and below to at least 200 F.

Although only one embodiment of the invention has been illustrated in the accompanying drawing and described in the foregoing specification, it is to be expressl understood that various changes, such as in the relative dimensions of the parts, materials used, and the like, as Well as the suggested manner of use of the apparatus of the invention, may be made therein without departing from the spirit and scope of the invention as will now be apparent to those skilled in the art.

What is claimed is:

1. Apparatus for generating electrical pulses and distributing the pulses in succession to a plurality of output devices connectable to a common conductor, comprising a storage condenser, a charging circuit including a current source for the condenser, said charging circuit comprising a distributor eriodically connecting one terminal of the current source to the common conductor through each of the output devices in succession, circuit means for periodically discharging the condenser through each of the output devices in succession, said discharging circuit means including said distributor and a switching device selectively rendered electrically conductive and non-conductive, and timed triggering means for con trolling the switching device.

2. Apparatus as claimed in claim 1, wherein the distributor includes means successively connected in both the charging circuit and the discharging circuit means whereby during any given charging and discharging cycle of the condenser the same output device forms a part of the charging circuit and the discharging circuit means.

3. Apparatus as claimed in claim 1, wherein each of the output devices comprises a transformer having a primary winding and a secondary winding, and a discharge gap connected to be energized by the secondary winding of the transformer, the primary winding being connected in the charging circuit and in the discharging circuit means by the distributor.

4. Apparatus as defined in claim 1 wherein the switching device is normally non-conductive electronic switching device.

5. Apparatus for generating a succession of timed electrical pulses, comprising a storage condenser, a charging circuit for the condenser, a circuit for periodically discharging the condenser, said circuits having a coil winding in common, an output circuit connected to be energized by the discharge of the storage condenser through said winding, the output circuit including at least one discharge gap, said discharging circuit including a solid state electronic switching device selectively rendered electrically conductive and no-conductive, and triggering means for controlling the switching device.

6. Apparatus as claimed in claim 5, wherein the triggering means includes means for generating a succession of timed electrical triggering pulses and for delivering such timed pulses to the switching device.

7. Apparatus as claimed in claim 6, wherein the triggering means includes a pickup coil and atriggering wheel rotating past the pickup coil to generate said triggering pulses in the coil, and comprising a capacitor and means selectively to operatively connect the capacitor in series with the pickup coil to thereby vary the timing of the discharging of the storage condenser.

8. Apparatus for generating a succession of electrical pulses comprising a storage condenser, a charging circuit for the condenser, a circuit for discharging the condenser,

said discharging circuit including a solid state switching device selectively rendered electrically conductive and nonconductive, said switching device being a rectifier having an anode, a cathode and a triggering gate, said rectifier being rendered conductive upon the reception at the gate of a positive triggering pulse having a minimum threshold value,

charge on the gate following each discharge of the storage condenser through the rectifier, and triggering means for generating a succession of electrical triggering pulses for controlling the switching device.

9. Apparatus as claimedin claim 8, wherein the circuit means for erasing the residual positive charge on the gate comprises a breakdown diode, resistor and a condenser connected in parallel, said parallel connected breakdown diode, resistor and condenser being connected in series in the discharging circuit.

10. An ignition system for an internal combustion engine having a plurality of cylinders, comprising a storage cc ndenser, an output device for each engine cylinder comprising a transformer and an igniter gap, charging circuit means including a current source for charging said condenser through the primary winding of a said transformer, discharging circuit means including a normally non-conductive electronic switching device for discharging said condenser through the primary winding of a said transformer, a distributor for periodically successively connecting the transformer primary windings in series with said condenser in said charging circuit means and said discharging circuit means, and means for controlling the switching device to periodically render the same successively conductive and non-conductive to the charge on the condenser.

11. Apparatus as claimed in claim 10, wherein the distributor includes means for simultaneously connecting the circuit means for erasing the residual positive vice to render the same said primary winding in both the charging circuit and the discharging circuit of the storage condenser during each charging and discharging cycle thereof.

12. An ignition system as claimed in claim 10, wherein the means for controlling the conductivity of the switching device includes a pickup coil and a triggering wheel rotating past the pickup coil to generate triggering pulses in the coil, and a capacitor adapted to be operatively connected in series with said pickup coil to vary the timing of the discharge at the igniter gap.

13. An ignition system as defined in claim 10 wherein the means for controlling the conductivity of the switching device comprises a breakdown voltage diode series connected in the anode-cathode circuit of the switching device and a capacitor connected in shunt across said diode.

14. An ignition system as defined in claim 13 comprising a resistor connected in shunt across said capacitor for dissipating the residual charge thereon while the switching device is non-conductive.

15. Electrical pulse generating apparatus comprising a storage condenser, means for charging said condenser, and a discharge circuit for said condenser comprising a normally non-conductive electronic switching device, a breakdown voltage diode connected in series with the cathode of said switching device and a capacitor connected in shunt across said diode.

16. Electrical pulse generating apparatus as defined in claim 15 comprising a resistor connected in shunt across said capacitor for'dissipating residual charges on said capacitor.

17. Electrical pulse generating apparatus as defined in claim 15 comprising means for applying intermittent triggering pulses to the control electrode of said switching delatter conductive to the charge on the storage condenser, said diode having a breakdown voltage at least as great as the voltage of said triggering pulses applied to the control electrode.

18. Electrical pulse generating apparatus as defined in claim 15 wherein said switching device is a silicon controlled rectifier having an anode, a cathode and a gate electrode.

19. Apparatus for generating a succession of electrical pulses comprising a storage condenser, a charging circuit for the condenser, a discharge circuit for the condenser including a solid state normally non-conductive electronic switching device having an anode, a cathode and a triggering gate, said switching device being rendered conductive upon the reception at the gate of an electrical triggering pulse having a minimum threshold value, means for generating a succession of electrical triggering pulses and applying the same to the gate for rendering the switching device conductive to charges on the condenser, and means for removing the effect of the triggering pulse on the switching device following each discharge of the storage condenser through the switching device to thereby facilitate recovery of the latter to a non-conductive state.

20. Apparatus as defined in claim 19 wherein said means for removing the effect of the triggering pulse comprises a capacitor series connected in said discharge circuit and means connected in shunt across the capacitor for limiting the magnitude of the charge assumed by the capacitor during each discharge of the storage condenser.

21. Apparatus as defined in claim 20 wherein said means connected in shunt across the capacitor includes a diode.

22. Apparatus as defined in claim 20 comprising a resistor connected in shunt across the capacitor for dissipating the charge on the latter between successive discharges of the storage condenser.

No references cited.

RICHARD B. WILKINSON, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,186,397 June 1, 1965 Donald C. Loudon or appears in the above numbered pat- It is hereby certified that err id Letters Patent should read as ent requiring correction and that the sa corrected below.

and in the heading to the printed In the grant, line 1 for "Ronald C. London",

specification, line 3, name of inventor, each occurrence, read Donald C. Loudon Signed and sealed this 19th day of October 1965.

EAL)

nest:

EDWARD J. BRENNER RNEST W. SWIDER nesting Officer Commissioner of Patents

Claims (1)

1. APPARATUS FOR GENERATING ELECTRICAL PULSES AND DISTRIBUTING THE PULSES IN SUCCESSION TO A PLURALITY OF OUTPUT DEVICES CONNECTABLE TO A COMMON CONDUCTOR, COMPRISING A STORAGE CONDENSER, A CHARGING CIRCUIT INCLUDING A CURRENT SOURCE FOR THE CONDENSER, SAID CHARGING CIRCUIT COMPRISING A DISTRIBUTOR PERIODICALLY CONNECTING ONE TERMINAL OF THE CURRENT SOURCE TO THE COMMON CONDUCTOR THROUGH EACH OF THE OUTPUT DEVICES IN SUCCESSION, CIRCUIT MEANS FOR PERIODICALLY DISCHARGING THE CONDENSER THROUGH EACH OF THE OUTPUT DEVICES IN SUCCESSION, SAID DISCHARGING CIRCUIT MEANS INCLUDING SAID DISTRIBUTOR AND A SWITCHING DEVICE SELECTIVELY RENDERED ELECTRICALLY CONDUCTIVE AND NON-CONDUCTIVE, AND TIMED TRIGGERING MEANS FOR CONTROLLING THE SWITCHING DEVICE.

Images