Protective control for vehicle starter and electrical systems

• US 4,209,816 A
• Filed: 07/07/1978
• Issued: 06/24/1980
• Est. Priority Date: 07/07/1978
• Status: Expired due to Term

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Hansen, James E.
• Primary Examiner(s): Salce, Patrick R.
• Application Number:
  US05/922,725
• Time in Patent Office: 718 Days
• Field of Search: 361/1, 361/23, 361/28, 361/239, 361/240, 361/241, 361/236, 123/179 BG, 123/179 A, 123/102, 290/37 R, 290/37 A, 290/38 R, 290/38 D, 307/10 R, 307/10 BP
• US Class Current: 361/23
• CPC Class Codes: B60R 16/0235 for lighting devices combined with starting or ignition devices for road vehicles
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: F02N 11/0848 with means for detecting successful engine start, e.g. to stop starter actuation
• CPC Class Codes: F02N 11/105 when the engine is already running F02N11/0848 takes precedence
• CPC Class Codes: H02H 11/002 in case of inverted polarity or connection; with switching for obtaining correct connection

Abstract

A protective control for the starter and electrical systems of a motor vehicle, including a main relay for controlling the electrical system, and a starter relay for controlling the starter system. Electronic logic is provided for the electrical system which: (1) prevents energization of the main relay if the battery polarity is reversed; (2) if the battery polarity is correct, turns on the main relay when a master switch is closed; and (3) maintains the main relay in an ON condition when an AC signal from the alternator is sensed even if the masterswitch is subsequently opened. The latter prevents disconnection of the battery from the electrical system while the engine is running. Electronic logic is also provided for the starter relay which: (1) after the main relay is closed, turns on the starter relay when a starter switch is closed, to thus permit cranking of the engine; (2) automatically deenergizes the starter relay when the AC signal from the alternator attains a designated threshold frequency, which corresponds to a pre-determined engine RPM at which it is desired to disengage the starter; and (3) has a hysteresis network to prevent subsequent re-energization of the starter relay until the AC signal from the alternator drops to a value substantially below the original threshold frequency, preferably when the engine is stopped or almost stopped, whereby the starter switch will re-energize the starter relay only if the master switch is closed and the engine is not running.

Claims

1. A protective control for the starter system of an engine which is cranked by a starter motor, comprising:

starter relay means in circuit with said starter motor;

frequency selective means responsive to engine RPM to automatically open said starter relay means above a predetermined threshold set frequency corresponding to a designated RPM level, to prevent cranking of said engine thereabove,

said frequency selective means including hysteresis means to prevent reclosing of said starter relay means until engine RPM drops to a lower level corresponding to a reset frequency less than said threshold set frequency, whereby to prevent recranking of said engine until engine RPM drops to said lower level;

transducer means responsive to engine speed to produce a signal whose frequency corresponds to engine RPM,

said frequency selective means having an input for receiving said transducer signal and an output controlling said starter relay means;

wherein said transducer signal, upon reaching said threshold set frequency, causes said output to switch states and also activates said hysteresis means to lower the frequency value necessary to cause switching of said output back to its original state;

said transducer means comprising an AC signal generator and input waveshaping means for receiving the AC signal and delivering a clear waveshape signal to said input of said frequency selective means;

said frequency selective means comprising a programmable frequency switch having an input receiving said transducer signal and a pair of opposite state outputs one of which is connected to said starter relay means and the other of which is connected to a hysteresis network, such that when the frequency of said transducer signal at said input reaches said threshold value, said outputs switch states such that said one output causes opening of said starter relay means and said other output causes said hysteresis network to lower the value of said threshold frequency down to said reset frequency;

said hysteresis network comprising a capacitor which is floated when the other of said outputs is in the first mentioned of its states, and which is connected in circuit with said frequency switch when said other of said outputs switches to its second mentioned state.

2. The invention according to claim 1 wherein said hysteresis network comprises a transistor which is biased into conduction by said second state of said other output to complete said circuit through said capacitor.

3. The invention according to claim 1 wherein said frequency selective means comprises a second capacitor connected to another input of said frequency switch for selecting the value of said threshold set frequency, said first capacitor being connected in parallel with said second capacitor when said other output is in said second state, said parallel combination of said capacitors determining the value of said reset frequency.

4. The invention according to claim 1 wherein said transducer comprises an alternator driven by said engine, and wherein said input waveshaping means comprises a transistor biased by the AC alternator signal to abruptly switch ON and OFF on leading and trailing edges of said AC signal, one of the emitter and collector of said transistor thus switching low and high and connected to said input of said frequency selective means for delivering a clean pulse shape signal thereto.

5. A protective control for the starting and electrical systems of a vehicle having an engine which is cranked by a starter motor and battery, comprising:

a main relay between said battery and said electrical system;

a starter relay between said main relay and said starter motor;

a master switch in circuit with said main relay;

a starter switch in circuit with said starter relay;

electronic logic for said main relay which;

(a) permits energization of said main relay when said master switch is closed; and

(b) senses engine RPM and will maintain said main relay closed even if said master switch is subsequently opened, whereby to prevent disconnection of said battery from said electrical system when said engine is running;

electronic logic for said starter relay which;

(a) after said main relay is closed, permits energization of said starter relay when said starter switch is closed, to thus enable energization of said starter motor and cranking of said engine;

(b) senses engine RPM and automatically de-energizes said starter relay at a predetermined set threshold engine RPM level to thus disengage said starter motor; and

(c) prevents subsequent re-energization of said starter relay and hence said starter motor until engine RPM drops to a reset level lower than said predetermined set threshold level;

transducer means responsive to engine speed to produce a signal whose frequency corresponds to engine RPM,

said electronic logic for said starter relay comprising frequency selective means having an input for receiving said transducer signal and an output controlling said starter relay;

said frequency selective means including hysteresis means such that said transducer signal upon reaching a predetermined set threshold frequency corresponding to said set threshold engine RPM level causes said output to switch states to de-energize said starter relay and also activates said hysteresis means to lower the input frequency necessary to switch said output back to its original state down to a reset frequency value less than said set threshold frequency and corresponding to said reset lower level engine RPM, said electronic logic for said main relay responding to the same said transducer signal for sensing engine RPM.

6. The invention according to claim 5 wherein said transducer comprises an AC signal generator, said invention further comprising input waveshaping means for receiving the AC signal and delivering a clean waveshape signal to said input of said frequency selective means.

7. The invention according to claim 6 wherein said transducer comprises an alternator driven by said engine, and wherein said input waveshaping means comprises a transistor biased by the AC alternator signal to abruptly switch ON and OFF on leading and trailing edges of said AC signal, one of the emitter and collector of said transistor thus switching low and high and connected to said input of said frequency selective means for delivering a clean pulse shape signal thereto.

8. The invention according to claim 5 wherein said frequency selective means comprises a programmable frequency switch having an input receiving said transducer signal and a pair of opposite state outputs one of which is connected to said starter relay the other of which is connected to a hysteresis network, such that when the frequency of said transducer signal at said input reaches said set threshold value, said outputs switch states such that said one output causes opening of said starter relay and said other output causes said hysteresis network to lower the value of said threshold frequency down to said reset frequency.

9. The invention according to claim 8 wherein said hysteresis network comprises a capacitor which is floated when the other of said outputs is in the first mentioned of its states, and which is connected in circuit with said frequency switch when said other of said outputs switches to its second mentioned state.

10. The invention according to claim 9 wherein said hysteresis network comprises a transistor which is biased into conduction by said second state of said other output to complete said circuit through said capacitor.

11. The invention according to claim 9 wherein said frequency selective means comprises a second capacitor connected to another input of said frequency switch for selecting the value of said threshold set frequency, said first capacitor being connected in parallel with said second capacitor when said other output is in said second state, said parallel combination of said capacitors determining the value of said reset frequency.

12. The invention according to claim 8 wherein said one output is high until the frequency of said transducer signal reaches said threshold set frequency whereafter said one output switches low and remains low until the frequency of said transducer signal drops below said reset frequency due to said hysteresis network, and further comprising a transistor in circuit with said starter relay and biased into conduction by said one output when in said high state to enable completion of a circuit through said starter relay whereby the latter may be closed to permit energization of said starter motor and cranking of said engine.

13. The invention according to claim 5 wherein said electronic logic for said main relay comprises signal detection means for detecting the presence of a signal from said transducer and for delivering said signal to a transistor in circuit with said main relay to bias said transistor into conduction to enable completion of a circuit through said main relay.

14. The invention according to claim 13 wherein closure of said master switch connects said battery to the base of said transistor to thus bias said transistor into conduction and hence energize said main relay.

15. The invention according to claim 5 wherein said control is a pre-assembled module which may be added to the existing circuitry of a vehicle having an alternator driven by the vehicle'"'"'s engine:

said module having a first terminal connectable to said battery through said master switch, said first terminal being connected internally of said module to said electronic logic for said main relay, said module having a second terminal connectable to said starter motor, said second terminal being connected internally of said module to one side of said starter relay, said module having a third terminal connectable to said battery in parallel with the series combination of said master switch and said first terminal, said third terminal being connected internally of said module to one side of said main relay, said module having a fourth terminal connectable to said electrical system, said fourth terminal being connected internally of said module to the other side of said main relay, said module having a fifth terminal connectable to said fourth terminal through said starter switch, said fifth terminal being connected internally of said module to said electronic logic for said starter relay, said module having a sixth terminal connectable to said alternator for feeding to said module an AC signal having a frequency corresponding to engine RPM, said sixth terminal being connected internally of said module to said electronic logic for said starter relay and to said electronic logic for said main relay.