US3270731A

US3270731A - Spring starter for internal combustion engine

Info

Publication number: US3270731A
Authority: US
Publication date: 1966-09-06
Anticipated expiration: 1983-09-06

Description

United States Patent 3,270,731 IGNITION SYSTEM Laurence F. Mieras, Livonia, Micl1., assignor to Ford Motor Company, Dear-horn, Mich, a corporation of Delaware Filed Aug. 3, 1964, Ser. No. 387,002 8 Claims. (Cl. 123-148) This invention relates to an ignition system for an internal combustion engine and more particularly to such an ignition system that employs a sol-id state switching device for controlling the energization of the primary winding of an ignition coil.

In the invention, a solid state switching device is employed to control the energization of the primary winding of the ignition coil from the electrical storage battery of the vehicle. It is known that excessive currents through a solid state device can destroy its operating characteristics. As a consequentce a current limiting resistor is employed to limit current through the solid state switching device.

During starting operations, means are employed for disabling this current limiting resistor provided that the terminal voltage of the battery is below a predetermined value or that the operating temperature of the battery and the system are below a predetermined temperature. Thus, during cold weather operations when the temperature of the battery is low and the output potential or" the battery is low, the current limiting resistor will be disabled or shorted out ofthe circuit containing the solid state switching device. This will permit sutiicient current flow through the solid state switching device and the primary winding of the ignition coil to generate sufficient- 1y high voltages in the secondary winding of the ignition coil to provide proper ignition.

If the terminal voltage of the battery, however, or the operating temperatures are sufficiently high, the current limiting resistor is retained in the circuit so that it performs its current limiting function. This protects the solid state switching device during starting operations at high temperatures where the terminal voltage of the battery is sufliciently high that the solid state switching device would be damaged if thecurrent limiting resistor were disabled.

In the preferred embodiment of the invention, the means for disabling the current limiting resist-or is coupled to the starting relay and comprises a normally closed circuit that will bypass the current limiting resistor upon energization of a starting circuit if the terminal voltage of the battery is below a predetermined level or it the temperature of the system is below a predetermined level. If, however, during starting operations, the terminal voltage of the battery is above a predetermined level or if the temperature of the system is above a predetermined level this normally closed circuit will open so that the starting relay is disabled from shorting out the current limiting resistor. Thus, during starting operations if the terminal voltage of the battery is sufficiently high that currents could reach unacceptable levels through the solid state switching device, the current limiting resistor is retained in the circuit to limit the current to suitable values.

An object of the present invention is the provision of an ignition system for an internal combustion engine employing a solid state switching device in which the current during starting operations through the switching device is efifectively controlled so that proper ignition voltages are generated at all times and so that the solid state switching component is properly protected from excessive currents during all starting operations.

Another object of the invention is the provision of an ignition system for an internal combustion engine in which "ice a solid state switching device employing a current limiting resistor is used in which the current limiting resistor is shorted out during starting operations if the terminal voltage of the battery is below a predetermined level.

A further object of the invention is the provision of an ignition system for an internal combustion engine employing a solid state switching device in which a current limiting resistor positioned to limit current through this solid state switching component is efiectively shorted out if the temperature of the battery and other components of the system is below a predetermined level.

Other objects and attendant advantages of the present invention will be more fully realized as the specification is considered in connection with the attached drawings, in which:

FIGURE 1 is a circuit diagram of the present invention, and

FIGURE 2 is a partial circuit diagram showing a modification of the present invention.

Referring now to the drawings in which like reference numerals designate like parts throughout the several views thereof, there is shown in FIGURE 1 the transist-orized ignition system of the invention that includes an ignition coil 10 having a secondary winding 11. The secondary winding 11 -is sequentially connected to spark plugs 12 through a distributor 13. The distributor 13 includes a rotating arm 14 :for sequentially connecting the spark plugs 12 to the secondary winding 11 in synchronism with the operation of the engine in which the ignition system is mounted.

The primary winding 15 of the ignition coil 10 is energized from the source of electrical energy or storage battery 16 under the control of a solid state switching device preferably in the form of a transistor 17 that is connected in series with the primary winding 15 and the s urce of electrical energy 16. This is accomplished by connecting the positive terminal 21 of the source of electrical energy 16 to the emitter 22 of transistor 17 by means of lead 23, lead 24, movable arm 25 of ignition switch 26, contact 27 of this switch, lead 28, current limiting resistor 29, lead 30, resistor 31 and lead 32. The collector 33 of the transistor 17 is connected to the primary winding 15 of ignition coil 10 through lead 34, winding 35 of a bistable electromagnetic switch 36, lead 37, lead 38 and resistor 41.

The control of transistor 17 is accomplished by means of a biasing circuit means 42 that includes a second transistor 43 having an emitter 44 connected to the base 45 of transistor 17 through diode 46. The collector 47 of transistor 43 is connected to ground through winding 48 of bistable electromagnetic switch 36 and a base current limiting resistor 49. The emitter 22 and the base 45 of transistor 17 are interconnected through output winding 50 of bistable electromagnetic switch 36 and a resistor 51.

The base 52 of transistor 43 is connected to collector 53 of transistor 54 by means of lead 55. The lead 55 and the collector 53 of transistor 54 are connected to ground through a resistor 56. The emitter 57 of transistor 54 is connected to lead 32 through resistor 58.

The base 60 of transistor 54 is connected through lead 61 to one terminal 62 of the output winding 63 of an electromechanical generator -64. The other terminal 65 of the output winding '63 is connected to a junction 66 between resistor 67 and the cathode 68 of diode 69. The anode 71 of the diode 69 is connected to junction 72 and this junction in turn is connected to one terminal of resistor 73. The other terminal of the resistor 73 is connected to lead 30. A resistor 74 has one terminal connected to junction 72 and the other terminal connected to junction 75, while a resistor 76 has one terminal connected to junction through lead 77 and the other electrical energy16. This causes the armature 96 of starting relay .94 to come into engagement with contacts 97 and 98. The engagement of the armature 96 with contacts 97 and 98 energizes the starting motor 102 from the source of electrical energy 16 through leads 23, 101, contact 97, armature 96, contact 98 and lead 103.

The engagement of the armature 96 with the contacts 97 and 98 of starting relay 94 also rebiases the biasing circuit 42 by connecting the base 60 of transistor 54 to the positive terminal 21 of the source of electrical energ 16. This biases the transistor 54 into a steady state nonconducting state and transistors 43 and 17 into a steady state conducting state during starting operations. The purpose of this is to retard rather than advance ignition timing during starting as more vfully described in my copending application S.N. 387,003 filed August 3, 1964.

The engage'ment of the armature 96 of the starting relay 94 with the contacts 97 and 98 also energizes winding 108 of cold start relay 106 through lead 23, lead 101, contact 97, armature 96 and contact 98. The cold start relay 106 is constructed so that a predetermined terminal voltage level of the source of electrical energy 16 is necessary to open the normally closed contacts 106. In a 12 volt battery system it is preferred to have the contacts 107 open when the terminal voltage of the battery during starting operations exceeds approximately 10.5 volts. 7 g

, Assuming that the terminal voltage of the battery is below the predetermined level mentioned above, as it would be during cold weather starting operations, the normally closed cont-acts 107 will remain closed when the starting circuit is energized by the movement of movable arm 86 into engagement with the contact 92'. This disables or shorts out the current limiting resistor 29 since the lead 30 is directly connected to the positive terminal 21 of the source of electrical energy 16 through lead 23, lead 101, contact 97, armature 96 and closed contacts 107.

On the other hand, if the terminal voltage of the battery is higher than the predetermined level, for example, 10.5 volts, the current through winding 108 of the cold start relay 106 will be suificiently high to open the normally closed contacts 107. Lead 30 which is connected to the transistor 17 is then energized from the source of electrical energy 16 through lead 23, lead 24, movable arm 25 and contact 92 of ignition switch 26, lead 28 and current limiting resistor 29. This is the same circuit as is employed to connect the transistor 17 to the source of electrical energy 16 during normal engine running conditions. The current limiting resistor 29 is maintained, therefore, in the circuit during starting operations when the terminal voltage of the source of electrical energy 16 is sufliciently high that the current limiting resistor 29 is needed to prevent excessive currentsthrough the transistor or solid state switching device 17.

An alternate form of the cold start relay 106 is shown in FIGURE 2. This embodiment is the same as the coldstart relay shown in FIGURE 1 except that the resistor 110 connected in series with the winding 108 IS replaced by a thermistor or negative temperature coefiicient resistor 110'. The thermistor 110' is positioned in the system to sense the temperature of the battery or source of electrical energy 16 and could be immersed, if desired, in the electrolyte of the battery 16.

At low temperatures the resistance of thermistor 110' will be high, and it will limit the current through the winding 108 during start-ing operations to a value under that required to open the normally closed contacts 107. During higher temperature operations, when it is desired to keep the current limiting resistor 29 in the circuit to limit current through the transistor or solid state switching device 17, the resistance of thermistor 110 will be sufficiently 6 low that sufiieient current flows through winding 108 to open contacts 107.

'It can be appreciated that the current limiting resistor 29 needs to be bypassed or disabled during low temperature starting operations to permit sufiiciently high ignition voltages to be generated in the secondary winding 11 of ignition coil 10 since during cold weather operations the terminal voltage of the source of electrical energy 16 may drop drastically.

The present invention thus provides an ignition system operated or controlled by a solid state switching device in which proper ignition voltages may be generated during all starting conditions and in which current through the device is effectively limited to proper values during all starting conditions.

It is to be understood that this invention is not to be limited to the exact construction shown and described but that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. An ignition system for an internal combustion engine comprising, an ignition coil having a primary winding, an electrical storage battery, a solid state switching device coupled to said electrical storage battery and said primary winding of said ignition coil for controlling the energization of said primary winding, a current limiting resistor in circuit with said solid state switching device for limiting current through said solid state switching device, and means coupled to said electrical storage battery and said current limiting resistor for disabling said current limiting resistor from its current limiting function during engine starting operations only when the electrical load coupled to said electrical storage battery during starting operations reduces the terminal voltage of said battery below a predetermined value and for retaini-ng said current limiting resistor in circuit to perform its current limiting function if the terminal voltage of said battery during starting operations is above said predetermined value.

2. An ignition system for an internal combustion engine comprising, an ignition coil having a primary wind ing, an electrical storage battery, a solid state switching device coupled to said electrical storage battery and said primary winding of said ignition coil for controlling the energization of said primary winding, a current limiting resistor coupled in circuit with said solid state switching device for limiting current through said solid state switching device, a starting circuit for the internal combustion engine, means coupled to said starting circuit and said electrical storage battery for energizing said starting circuit from said source of electrical energy during starting operations, and means coupled to said electrical storage battery, said starting circuit and said current limiting resistor for disabling said current limiting resistor from its current limiting function during engine starting operations if the terminal voltage of said electrical storage battery during starting operations when the electrical load of said starting circuit is coupled to said electrical storage battery is below a predetermined value and for retaining said current limiting resistor in circuit to perform its current limiting function if the terminal voltage of said battery during starting operations when the electrical load of said starting circuit is coupled to said electrical storage battery is above said predetermined value, said last mentioned means including temperature responsive means for varying said predetermined value as an inverse function of the temperature of the system.

3. An ignition system for an internal combustion engine comprising, an ignition coil having a primary winding, an electrical storage battery, a solid state switching device coupled to said electrical storage battery and said primary winding of said ignition coil for controlling the energization of said primary winding, a current limiting resistor coupled in circuit with said solid state switching device for limiting current through said solid state switching device, and means coupled to said electrical storage battery and said current limiting resistor for disabling said current limiting resistor from its current limiting function during engine starting operations only when the electrical load coupled to said electrical storage battery during starting operations reduces the terminal voltage of said battery below a predetermined minimum, said last mentioned means including temperature responsive means for sensing the temperature of said system including said battery for modifying said predetermined minimum value as an inverse function of temperature.

4. An internal combustion engine ignition system comprising, an ignition coil having a primary and a secondary winding, a plurality of spark plugs, a distributor operated in timed synchronism with the engine for sequentially coupling said spark plugs with said secondary winding of said ignition coil, a source of electrical energy, a solid state switching device and a current limiting resistor connected in series with said primary winding of said ignition coil, means coupled to said solid state switching device and operable in timed synchronism with said distributor and the engine for periodically switching said solid state switching device between conducting and nonconducting states, a starting circuit for the internal combustion engine, means coupled to said source of electrical energy, and said starting circuit for energizing said starting circuit from said source of electrical energy during starting operations, and means coupled to said starting circuit and said current limiting resistor for shorting out said current limiting resistor during engine starting operations only when the electrical load of said starting circuit that is coupled to said source of electrical energy during starting operations reduces the terminal voltage of said source of electrical energy below a predetermined minimum, said last mentioned means including temperature responsive means for increasing said predetermined minimum as the temperature of the system decreases and for decreasing said predetermined minimum as the temperature of the system increases.

5. An internal combustion engine ignition system comprising, an ignition coil having a primary and a secondary winding, a plurality of spark plugs, a distributor operated in timed synchronism with the engine for sequentially coupling said spark plugs with said secondary winding of said ignition coil, a source of electrical energy, a semiconductor switching device and a current limiting resistor connected in series with said primary winding of said ignition coil, means coupled to said semiconductor switching device and operable in timed synchronism with said distributor and the engine for periodically switching said semiconductor switching device between conducting and nonconducting states, a starting circuit for the internal combustion engine, means coupled to said source of electrical energy and said starting circuit for energizing said starting circuit from said source of electrical energy during starting operations, and means coupled to said starting circuit and said current limiting resistor for shorting out said current limiting resistor during starting operations if the terminal voltage of said battery during starting operations when the electrical load of said starting circuit is coupled to said battery is below a predetermined level and for retaining said current limiting resistor in circuit if the terminal voltage of the battery during starting operations when the electrical load of said starting circuit is coupled to said battery exceeds said predetermined level.

6. An internal combustion engine ignition system comprising, an ignition coil having a primary and a secondary winding, a plurality of spark plugs, a distributor operated in timed synchronism with the engine for sequentially coupling said spark plugs with said secondary winding of said ignition coil, a source of electrical energy, a semiconductor switching device and a current limiting resistor Connected in series with said primary winding of said ignition coil, means coupled to said semiconductor switching device and operable in timed synchronism with said distributor and the engine for periodically switching said semiconductor switching device between conducting and nonconducting states, a starting'circuit for the internal combustion engine, mean-s coupled to said source of electrical energy and said starting circuit for energizing said starting circuit from said source of electrical energy during starting operations, and means coupled to said starting circuit and said current limiting resistor for shorting out said current limiting resistor during starting operations if the terminal voltage of said battery during starting operations when the electrical load of said starting circuit is energized from said source of electrical energy is below a predetermined level and for retaining said current limiting resistor in circuit if the terminal voltage of the battery during starting operations when the electrical load of the starting circuit is energized from said source of electrical energy exceeds said predetermined level, said last mentioned means including means for sensing the temperature of said system including said battery and for varying the predetermined level as an inverse function of temperature.

7. An internal combustion engine ignition system comprising, an ignition coil having a primary and a secondary winding, a plurality of spark plugs, a distributor operated in timed synchronism with the engine for sequentially coupling said spark plugs with said secondary winding of said ignition coil, a source of electrical energy, a semiconductor switching device and a current limiting resistor connected in series with said primary winding of said ignition coil, means coupled to said semiconductor switching-device and operable in timed synchronism with said distributor and the engine for periodically switching said semiconductor switching device between conducting and nonconducting states, a starting relay having a winding, an armature and a pair of spaced contacts, one of said contacts being connected to said source of electrical energy, a starting motor, the other of said contacts being connected to said starting motor, switching means connected to said source of electrical energy and operable when operated to connect said source of electrical energy to said winding, said winding when energized moving said armature into engagement with said contacts to energize said starter motor, a cold start relay including a winding connected to the contact of said starting relay which is connected to said starting motor and a set of normally closed contact-s connected to said armature of said starting relay and to the side of said current limiting resistor adjacent said semiconductor switching device, said winding developing suificient magnetomotive force to open said normally closed contacts when the terminal voltage of said source of electrical energy is above a predetermined level but developing insufficient magnetometive force to open said set of normally closed contacts when the terminal voltage of said source of electrical energy is below said predetermined level.

'8. An integral combustion engine ignition system comprising, an ignition coil having a primary and a secondary winding, a plurality of spark plugs, a distributor operated in timed synchronism with the engine for sequentially coupling said spark plugs with said secondary winding of said ignition coil, a source of electrical energy, a semiconductor switching device and a current limiting resistor connected in series with said primary winding of said ignition coil, means coupled to said semiconductor switching device and operable in timed synchronism with said distributor and the engine for periodically switching said semiconductor switching device between conducting and nonconducting states, a starting relay having a winding, an armature and a pair of spaced contacts, one of said contacts being connected to said source of electrical energy, a starting motor, the other of said contacts being connected to said starting motor, switching means connected to said source of electn'cal energy and operable when operated to connect said source of electrical energy to said winding, said Winding when energized moving said armature into engagement With said contacts to energize said starter motor, a cold start relay comprising a winding connected to the con tact of said starting relay which is connected to said starting motor and a set of normally closed contacts connected to said armature and to the side of said current limiting resistor adjacent said semiconductor switching device, a negative temperature coefficient resistor connected in series with said Winding of said cold start relay, the resistance of said negative temperature coefficient resistor being sufficiently low when the temperature is above a predetermined level to permit sufiicient magnetomotive force to be developed by said winding to open said normally closed contacts and being sufliciently high when said temperature is below said predetermined level to prevent sufiicie-nt magnetomotive force from being developed in said Winding to open said normally closed contacts.

References Cited by the Examiner UNITED STATES PATENTS 1,716,895 6/1929 Mallory 123- 148 2,807,729 9/1957 Redick 123-179 3,020,904 2/1962 Kerr 123--148 3,173,410 3/1965 McLaughlin 123-148 MARK NEWMAN, Primary Examiner.

15 RICHARD B. WILKINSON, Assistant Examiner.

p 6, 1966 J. R. HARKNESS 3,270,732

SPRING STARTER FOR INTERNAL COMBUSTION ENGINE Filed Aug 12, 1964 3 Sheets-Sheet 1 O O L I4

Claims

1. AN INGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING AN IGNITION COIL HAVING A PRIMARY WINDING, AN ELECTICAL STORAGE BATTERY, A SOLID STATE SWITCHING DEVICE COUPLED TO SAID ELECTRICAL STORAGE BATTERY AND SAID PRIMARY WINDING OF SAID INGNITION COIL FOR CONTROLLING THE ENERGIZATION OF SAID PRIMARY WINDING, A CURRENT LIMITING RESISTOR IN CIRCUIT WITH SAID SOLID STATE SWITCHING DEVICE FOR LIMITING CURRENT THROUGH SAID SOLID STATE SWITCHING DEVICE, AND MEANS COUPLED LIMITING RESISTOR BATTERY AND SAID CURRENT LIMITING RESISTOR FOR DISABLING SAID CURRENT LIMITING RESISTOR FROM ITS CURRENT LIMITING FUNCTION DURING ENGINE STARTING OPERATIONS ONLY WHEN THE ELECTRICAL LOAD COUPLED TO SAID ELECTRICAL STORAGE BATTERY DURING STARTING OPERATIONS REDUCES THE TERMINAL VOLTAGE OF SAID BATTERY BELOW A PREDETERMINED VALUE AND FOR RETAINING SAID CURRENT LIMITING RESISTOR IN CURCUIT TO PERFORM ITS CURRENT LIMITING FUNCTION IF THE TERMINAL VOLTAGE OF SAID BATTERY DURING STARTING OPERATIONS IS ABOVE SAID PREDETERMINED VALUE.