US 3809915 A
A circuit interrupting means is adapted to be interposed along a circuit line from a current source. Means are included for actuating the circuit interrupting means to interrupt the circuit line only during the absence of current flow therethrough, and means for re-establishing the circuit line coincident with a current demand upon the source through an auxiliary circuit coupled thereto.
Description (OCR text may contain errors)
1 United States Patent 1191 1111 3,809,915 Bost v May 7, 1974  ELECTRICAL POWER DELAY AND 2,931,918 4/1960 Shapirom; 307 10 BP CUTOUT CIRCUIT 1,591,149 7/1926 Waltamath 200161.45 R I 3,646,354 2/1972 Von Brimer "307/10 BP  Inventor: Charles H. Bost, Winter Haven, Fla. 1
 Assignee: BK 8; K Enterprises Inc., Orlando, Primary Examiner-Robert K. Schaefer Fla. Assistant Examiner-M. Ginsburg  Filed Dec 8 1972' Attorney, Agent, or Firm-Duckworth, Hobby & Alle 21 A 1. N 1: 313 455 1 pp 0 57 ABSTRACT 52 us. (:1 307/10 AT, 340/64 A cifcu" interrupting means is adapted  Int. Cl l-l02g 3/00 posed along a circuit line from a Current source'  Field of Search 307/10 R 10 AT, 10 BP Means are included for actuating the circuit interrupt- 307/10 180/114. 346/63 64 65 ing means to interrupt the circuit line only during the 2O0/61"45 absence of current flow therethrough, and means for re-establishing' the circuit line coincident with a cur-  References Cited rent demand upon the source through an auxiliary cir- UNlTED STATES PATENTS coupled 2,876,429 3 1959 16 Claims, 2 Drawing Figures Noztitz 340/64 STARTER 14 RELAY 2 22 26 24 i F H I L L ll V40 L FUSE BLOCK Z 48 52 5o 18 1GN1TION 11 SWITCH i- ATENTEDMAY 7:914 3Q809l9l5 SHEEY 1 UP 2 STARTER 12 22. 26 24 my & j l I T I 4O 42 16L FUSE IL BLOCK 48 5O 1/ IGNITION 44 SWITCH 4% I L27 2s PATENTEDUAY 7 I974 SHEEI 2 BF 2 STARTER RELAY I2 5 "l m l 16L FUSE BLOCK 7 52 IGNITION 44 I SWITCH IGNITION COIL ELECTRICAL POWER DELAY AND CUTOUT CIRCUIT BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates'to time delay and cutout circuits, and in particular, relates to such circuits which are designed to completely de-energize the electrical system of an automobile under certain conditions.
2. Description of the Prior Art There are a variety of prior art circuit arrangements for providing a time delay period after the ignition switch of an automobile is opened, to maintain an energizing circuit to the headlights to provide the operator with an opportunity to reach another area before the headlight circuit is de-energized. Brock, in U. S. Pat. No. 3,476,975, teaches a circuit for de-energizing an automobile headlamp circuitafter a time delay, and includes a warning indicator to advise the operator that the headlamp switch has been left in the on position. Brock also discloses that related arrangements are taught by Crum in U. S. Pat. No. 2,751,507; by Herridge 'et al. in 3,125,702; and in U. S. Pat. No. 3,374,394.
Carruth et al., in U. S. Pat. No; 3,544,838, teaches a headlamp interrupting circuit employing an RC discharge circuit for determining the time interval, and further including means for adjusting the time delay period. Similar arrangements are disclosed by Chunn et al. U. S. Pat. No. 3,546,527 and by Brock in U. S. Pat. No. 3,626,239. Gassei et al in U. S. Pat. No. 3,548,252 teach an arrangement whereby the headlamp circuit is deenergized after the ignition switch is opened and the operators door is opened.
Other automotive circuits are employed to protect auxiliary components, such as the lights, fan, turn indicators, radio and the like; see for example U. S. Pat. Nos. 3,152,259 to Heine, and 3,623,131 to Russell. Further, an automatic starting switch circuit is disclosed by Dyer in U. S. Pat. No. 2,292,367..
SUMMARY OF THE INVENTION THE DRAWING FIG. 1 is a schematic diagram of one embodiment ofa circuit in accordance with the present invention.
FIG. 2 is a schematic diagram of a second embodiment of a circuit in accordance with the present invention.
DETAILED DESCRIPTION An embodiment of a circuit in accordance with the present invention will now be described with reference 'to FIG. 1. The circuit is described as principally em ployed in an automobile of the type having an ignition switch and a braking system. It will be understood,
however, that the circuit may actually be employed in a variety of applications.
The circuit, referred to generally as 10, is adapted to be interposed along a circuit line 12, i.e. the battery cable from a current source, such as a wet cell battery 14 in the automobile. As shown in FIG. 1, the circuit line 12 is coupled to the positive electrode of the battery 14, with the negative electrode grounded, as to the chassis. It will be understood that the battery terminals may be reversed as is the practice in some European automobiles. In this embodiment, the circuit line 12 comprises the battery cable between the battery 14 and the fuse block 16 and ignition switch 18 of the automobile.
Means for interrupting the circuit line 12 is provided. In the present embodiment, this interrupting means comprises a normally open magnetic rela'y 20. Such relays are well known in the art, and include two terminals 22, 24 and a normally open contact element 26 for bridging the two terminals when a coil within the relay 20 is energized.
The automobile includes a brake switch 28 (generally operated by pressure applied on the brake pedal) and two brake lights 30, which are connected in parallel with each other, and in series with the brake'switch to ground. As shown in FIG. 1., the circuit 10 further comprises an NPN bipolar transistor 32' (PNP for positive grounded systems) having emitter, base and collector terminals 34, 36 and 38, respectively. The emitter terminal 34 of the transistor 32 is coupled to the circuit line 12, the base terminal36 is coupled to afirst side 27 of the brake switch 28, and the collector terminal 38 is coupled to a first terminal 40 of the coil of the magnetic relay 20, the other terminal 42 of the coil being grounded.
The brake switch 28 is coupled on the second side 29 thereof to the first coil terminal 40 of the magnetic relay 20, through a diode 44 which is poled so as to allow current to flow only from the 'second side 29 of the brake switch 28 into the magnetic relay 20. In this example the anode of diode 44 is coupled to the second side 29. Again, however, the polarity of the diode 44 and other diodes described below would be reversed for a positively grounded system. The first side 27'of the brake switch 28 is coupled to an associated fuse in the fuse block 16 through a second diode 46, which is poled so as to allow current to 'flow only from the fuse block 16 and into the brake switch 28, when the brake switch is closed.
One hot side of the ignition switch 18 is coupled via a circuit loop 47 to the first terminal 40 of the mag netic relay 20. In this context the hot side of the ignition switch 18 may be either the pin corresponding. to the starter switch, or the pin corresponding to the accessory switch, which allows some of the auxiliary circuits in the automobile, such as the radio, for example, to be energized. It is preferred to employ the latter. A third diode 48 is interposed between the ignition switch 18 and the magnetic relay 20 to allow current to flow only in the direction from the ignition switch 18 to the magnetic relay.
A normally open time delay relay 50 is connected between the ignition switch 18 and the emitter terminal 34 of the transistor 32. In this embodiment, the time delay relay 50 comprises a well known encapsulated heater-operated relay having two relay contacts 52, 54 and a heater element 56. One of the relay contacts 52 is coupled to the emitter 34 of the transistor 32, and the other relay contact 54 is coupled to the cathode of the third diode 48. The heater element 56 is coupled in series between the anode of the third diode 48 and ground.
The circuit of the present invention operates in the following manner. With the ignition switch 18 in the of position, the closure 26 between terminals 22 and 24 of the magnetic relay is open and conse-' quently no current can flow through the circuit line 12 from the battery 14. To reestablish the circuit line 12, the operator of the automobile turns the ignition switch 18 to the on or Accessory position. Thereafter the operator depresses the brake pedal. This causes a small (base, or control) current to flow from the battery 14 through the transistor 32 from the emitter 34 through the base 36, through the brake switch 28 and the brake lights 30 to ground; The majority of current flow in the transistor 32 flows from the emitter 34 to the collector 38, and into the first coil terminal of the magnetic relay 20 causing the normally open contact 26 to close and thereby re-establish the circuit line 12. Current then flows from the battery 14 into the fuse block 16 and through the ignition switch 18. I
If the operator has not, in fact, turned the ignition switch 18 to the on position, current will not flow into the ignition circuit but will only flow into the auxiliary braking circuit'so long as the brake. pedal remains depressed. If the ignition switch 18 is properly in the on position, current flows out of the ignition switch 18 and through the circuit loop 47 into the first coil terminal 40 of the magneticrelay20. This current then keeps the relay 20 latched after the brake pedal is released and current ceases to flow through the auxiliary circuit defined by the braking system.
As shown in FIG. 1, circuit loop 47 is also coupled to the time delay relay 50. After the automobile has been in operation for a period of time, the heater element 56 will close the bi-metallic relay contacts 52, 54 and further establish the circuit line 12 via the transistor 32. When the ignition switch 18 is turned to the off position, the time delay relay 50 will maintain the circuit line 12 until such time is needed for the contacts 52,54 to cool and interrupt the circuit line 12. In this way, auxiliary circuits other than the brake lights (such as the headlights, for example) may be left energized without consideration by the operator prior to leaving the vehicle.
A second embodiment of the circuit of the present invention is shown in FIG. 2. The circuit 70 of FIG. 2 is essentially identical to that of FIG. 1, and further includes a normally closed double-pole, single-throw impact switch 60 of a known type interposed between the ignition switch 18 and the magnetic relay 20. The impact switch 60 may be selected so as to open upon anypredetermined force. Specifically, one throw of the impact switch 60 is connected between the collector 38 and one relay contact 54 of the time delay relay 50. The other throw of the impact switch '60 is connected between the ignition switch 18 and the ignition coil 62.
In the event the automobile is involved in a collision of sufficient impact, the impact switch 60 will override the time-delay relay 50, and de-energize the magnetic relay 20, thus interruptingthe circuit line 12. In addition, the impact switch 60 interrupts the circuit line between the ignition switch 18 and the ignition coil 62. This greatly reduces the fire hazard due to the presence of spilled 4 gasoline. In addition, however, the operator may still reestablish current flow through the circuit line 12 by depressing the brake switch 2 The present invention provides several advantages. For example, the main circuit line of an automobile, i.e. the battery cable, is automatically interrupted when the vehicle is not attended. This protects all of the battery powered circuits from short circuits. Further, reestablishing the battery line in the circuit of the present invention requires two operations, thus reducing the possibility of inadvertent starting by small children.
In addition, the embodiment described above-does not interrupt the brake system, and thus the brake lights will function in the intended manner regardless of whether or not the ignition of automobile is in on position. I
1. A circuit for use with a current source, said circuit comprising:
circuit interrupting means adapted to be interposed along a circuit line from said current source; means for controlling said circuit interrupting means, when connected in-said circuit line, to interrupt said circuit line only responsive to the absence of current flow therethrough; and
means for reestablishing said circuit line, after interruption, coincident with a'current demand upon said source through at least one of auxiliary circuits coupled thereto.
2. A circuit as recited in claim 1 in combination with circuitry in a vehicle whereinsaid current sourceis of a type having an ignition switch coupled to said circuit line and auxiliary circuits coupled to said current source, and wherein said reestablishing means reestablishes said circuit line onlywhen said'ignition switch is closed and after a current demand on said source is made through one of said auxiliary circuits.
3. The combination as recited in claim 2 wherein said vehicle comprises a braking system including brake lights, and wherein one of said auxiliary circuits comprises means for actuating said brake lights.
4. The combination as recited in claim 2 wherein said circuit interrupting means comprises a normally open magnetic relay, and wherein said. controlling means maintains said magnetic relay closed during periods when said ignition switch is closed and after said current demand is made through said auxiliary circuit.
5. The combination as recited in claim 4 wherein said means for maintaining said magnetic relay closed comprises a circuit loop from said ignition switch to said magnetic relay.
6. The combination as recited in claim 5 further comprising time-delay means for maintaining said circuit line closed for a predetermined period of time after said ignition switch is open and during periods when no current demand is made through said auxiliary circuit.
7. The combination as recited in claim 6 further comprising means for interrupting said circuit line and overriding said time-delay means upon said vehicle impacting at a predetermined force.
8. The combination as recited in claim 6 wherein said time-delay means comprises a normally open timedelay relay coupled in parallel with said magnetic relay between said loop and the normally open side of said circuit line.
9. The combination as recited in claim 8 wherein said time-delay relay comprises an internal heater element, and wherein said heater element is coupled to said loop.
10. A circuit as recited in claim 9 further comprising means for blocking current flow into said ignition switch during current flow from said current source through said auxiliary circuit.
11. A circuit as recited in claim 1 further comprising means for detecting a predetermined impact force and interrupting said circuit line in response thereto.
12. A circuit adapted for use with an automobile of the type having a current source for supplying current to an ignition switch and auxiliary circuits coupled to said current source, said circuit comprising:
normally open circuit interrupting means adapted to,
be interposed along a circuit line between said current source and said ignition switch;
means for controlling said circuit interrupting means, when connected in said circuit line, to interrupt said circuit line only responsive to the absence of current flow therethrough; and
means for closing said circuit interrupting means, after interruption of said circuit line, coincident with said ignition switch being closed and current 6 flow from said current source through one of said auxiliary circuits.
13. A circuit as recited in claim 12 wherein said closing means comprises an active circuit element having two electrodes and an electrode adapted to control current flow between said two electrodes, one of said two electrodes adapted to be coupled to said current source, the other of said two electrodes adapted to be coupled to said circuit interrupting means and said control electrode adapted to be coupled to one of said auxiliary circuits.
14. A circuit as recited in claim 13 in combination with circuitry in said automobile comprising said ignition switch coupled along said circuit line between said circuit interrupting means and said other electrode.
15. The combination as recited in claim 14 wherein one of said auxiliary circuits comprises a switch coupled between said control electrode and said other electrode.
16. The combination as recited in claim 15 further comprising time-delay relay means coupled between said two electrodes for maintaining said circuit interrupting means closed for a time-delay period subsequent to said ignition switch being opened.