US2572397A - Engine starter control system - Google Patents

Description

Oct. 23, 1951 B. H. SHORT ETAL ENGINE STARTER CONTROL SYSTEM 2 Sl-IEETS-SHEET 1 Filed Oct. 30, 1946 ENG/IVE I40 I? I? I1 Mk NBA Oct. 23, 1951 B. H; SHORT ETAL ENGINE STARTER CONTROL SYSTEM Filed Oct. 30, 1946 2 SHEETS-SHEET 2 LL 16M I N VEN TOR5 3 iatented Oct. 23, 1951 ENGINE STARTER CONTROL. SYSTEM Brooks H; Short, Anderson, and John W; Dyer, Pendleton, Ind;, assignors to General Motors Corporation, Detroit, Mich, a corporationof Delaware Applicationoctober 30, 1946, Serial'No. 706,618:

1 Claim:

Thisinvention relates to engine starter control systems and aims to prevent use of the starter while the engine is running.

The-object of the invention is accomplished b the use of a relay switch which at the maximum crankingv speed: maintains its contacts closed so that the starting motor can be operated in the usual manner by a starter switch, The electromagnet of the-"relay is responsive to the voltage of'the generator which, below the cut-in speed when the cutout relay is open, i's separately excitedfrom the battery and'is self-excited'when the cutout: relay closes. By such arrangement, the relay switchrwill separate'its contacts in the starter 'controlc'ircuit' ata speed'above the maximum cranking speed'of the engine and well below, the cut-in speed so thatthecranking is discontinued automatically before engine speed increases very" much above themaximum cranklngspeed after thegengine becomes self operative. This is of: advantage to theengin'e starter because thestarting motor'pinion is automaticallyv disengagedfrom the engine flywheel gear at a speed considerably lower than-the minimum sustaining speedof-theengine; Another advantage is that the relayswitch holds its contacts open until the engine speed falls to practically zero. This'result is obtainedbecause below engine cutin speed, the generatorchanges from self-exciting'status-to separately-exciting status whereby 'its voltage output below cut-in speed isvery much higher-than it would be if the generator were self-excited below cut-in speed; Consequently; the relay'holds its contacts open until generator speed practically is zero.

Further objects 'and'advantages of the present invention will-'be apparent from the following description, reference being had' to the'accompanying drawings, wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

Figs; 1, 2, 6, 7 and Bare wiring diagrams embodying the invention.

Fig; 3 is a chart for'illustrating the operation of the generator" when self-excited and whenv separately+excited1 Fig: 4' is a wiring diagram showing, in detail, one of theunits" of the other diagrams.

Referring-to- 1, a generator lfldriven by the engine hasjone terminal grounded and the other connectedwith' a wire H connected with a terminal 12" of a regulator and cutout relay unit-l5; One'end' of the holdwinding 1310f the generator is connected "with'terminal' l 4" of unit [9. Terminal I6 of unit-l5 connected"with- 2 wire, H". Aswitc'h': lti'connects wire IT with wire: 19 connected with theigniti'on apparatus'as well as: field coil" l3;

Wire I1 is" connected withbattery 20 which is grounded and with a" contact 2| of a starter switch 25 having a contact 22 for'connecti'ng contact 2! with a contact 23: A spring 24"urgescontact 22 away from=contacts21 and 23'. Contact 23 is connected with blade 26' of a" relay 30. The blade 26 carries a contact 21'n0rnrally engaging arontactZBficonnected with a wire-291 Relayy30 includes a'core 32surrounded'by magnet coil 31 which is grounded atone end and" which isconnectedat the other end with wire '1 l;

Wire ZBlS'COIlIIGCtBd With a finewire magnet coil 33- and' with a coarse" wiremagnet coil 34" of a solenoid 35- -having-an 'armature36' insulat ingly supporting a contact 31 for connecting acontact"connected-withWire" H' With a con'- tact 39. A spring 360' normally maintains'coirtact 31'- out of engagement with contacts 38 and" 395 A" starting motor-wwhic'h is groundedhasits field coil' H connected by wire with contact 39 connected with'coil 34-.

Unit I 5; shownindetail'in-Fig; 4; is a combinedv voltage regulator; current regulator andcutout relay. The cutout relay 50 comprisesanarmatu're" 5'! attachedto a spring blade "52 carrying a v contact 53 adaptedtoengage a' contact 54*conneetedwith the terminal-[6'3 T-he'relay includes" grounded and carrying" a coarse winding; 5-! connected at one-end tobla'de 52';

Current regulator fillhas a coil 6i connectedat-oneend with winding 51ofrelay 50 'and'at'the' other end-with the terminal 12. Coil 61 surrounds a core" 6-2 facinganarmature 63 carried by a spring blade 64-carrying-acontact 65-nor= mally engaging a' contact'SG- connected with at wire 611 The-voltage regulator-'10 comprises'a core H surrounded by a coil 12'. connected at one end" with-wire-6T-and at the other end" with terminal. M'andwi't'ha' wire-131;connectedlwith a resistance '14 whicl'ris grounded and with a'iiresistance 1 5. which is' connected with wireTG which connects blade 5 64 of-regulatbr *with a. contact 11 normallyengaged by a" contact "carried by a spring with wire 82 connected" with the-cutout relay" windings 59 and 56*andwiththespringblade 51".

Theoperatlon-0f the/system, shown in Fig. 1;.

is as follows:

To start the engine the ignition is turned on by closing switch I8. Current then flows from the battery 20 to the ignition apparatus through wire II, switch I8, and wire I9 and also to the generator field I3 and out through the terminal I4 and thence to ground through coil I2 of regulator I0, wire 61, contacts 66, 65 of the regulator 60, blade 64, wire I6, contacts 11, I8 of regulator I and armature I9 which is grounded. The starter switch 25 is closed, thereby connectin solenoid coil 33 with the battery through wire 29, contacts 21, 28 of relay 30, blade 26, starter switch contacts 23, 22, 2I. The solenoid coil 34 contact 31 to engage contacts 38 and 39 whereupon the coil 34 is short-circuited and the solenoid remains in circuit closing status solely by the energization of the coil 33. The starting motor 40 is directly connected with the battery through Wire 42, contacts 39, 31, 38 and wire II. During'the cranking of the engine, the generator operates as a separately-excited generator and produces an output represented by the line A-B (Fig. 3). The battery supplies current to the field at 5.5 volts, for example, if the battery is fairly well charged. 'Below maximum cranking speed, about 300 R. P. M. generator speed or 150 R. P. M. engine speed, the maximum voltage output of the generator is below two volts which is insufiicient to cause relay 30 to separate its contacts 21 and 28. Relay 30 is constructed so as to separate its contacts at 2.25 volts and to close its contacts when the voltage impressed on its coil is 1.2 volts. Therefore, when the engine becomes self-operative, the generator output when self-excited, will reach 2.25 volts at about 360 R. P. M. generator speed or 180 R. P. M. engine speed. Therefore, long before the speed of the engine can rise to cut-in speed or even minimum idling speed which is about 700 generator speed and 350 engine speed, the circuit of the solenoid 35 and of the motor 40 will have been interrupted.

If the generator were not separately-excited below the generator cut-in speed, 1000 R. P. M., for example, the voltage generated would be that represented by the curve ACB which drops off rapidly to a low value as generator speed decreases. Therefore, it is necessary to provide for separate excitation of the generator, otherwise the relay 30 would close its contacts while the engine is idling, thereby making it possible to operate the starter by closing the starter switch 25 while the engine is in operation. Even with a relatively weak battery supplying the separately-excited field at 3 volts for example, the relay 30 would remain open at idling speed because the voltage then would be about 2.7 volts.

Coil 56 of cutout relay 50 is in circuit with coil 51 of the relay and coil 6| of the current regulator 60 and terminal l2. When the generator attains speed of about 1000 R. P. M., the excitation of the coil 56 is suflicient to cause the attraction of armature 5I of the cutout relay to close its contacts 53 and 54, thereby causing current to flow from the generator to terminal I2, coil 6| of current regulator 60 and coil 51 of relay 50. Relay 50 remains closed until generator voltage falls sufliciently below battery voltage to cause reversal current in coil 51 to buck the magnetism produced by coil .56 whereupon the relay 50 opens to prevent discharge of the battery. 1 I I While relay 50 is closed, the generator voltage for various speeds above 1000 R. P. M. is indicated by the line B-D-E. The maximum voltage, represented by line DE, is limited by the voltage regulator I0 which operates in the usual manner to separate contact I8 from contact 11, thereby causing the reducion of field excitation by resistances I5 and 74. The regulator will maintain the voltage between 7.2 and 7.8, for example, when cold and between 7.2 and 7.6 when hot. Current output is limited by current regulator 60 which on exceeding a predetermined current flow through its winding BI, causes contact 65 to separate from contact 66 whereby resistance I4 becomes efiective to reduce field excitation.

In the circuit shown in Fig. 2, the starter switch 25 and the relay 30 do not control the starting motor solenoid directly but indirectly through the relay 90 having a. magnet coil 9I surrounding a core 92 and grounded at one end and connected at the other end with contact 28 of relay 30. When coil 9| is energized by the closing of switch 25 while the contacts of relay 30 are closed, a contact 93 on a spring'blade 94 is caused to engage a contact 95, thereby connecting the battery through wire I'I, contacts 95, 93, blade 94 and a wire 96 with the winding 33 and 34 of the solenoid 35. By this arrangement the contacts In the circuit diagram shown in Fig. 5, the I closing of the starter switch 25 to crank the en- Y gine places the coil 9| of the relay 90 and the coil 3I of the relay 30 in series with the battery 29 after the ignition switch 59 is closed. At a coil 9I of relay 90 is then short-circuited. The

relays 30 and 90 of Fig. 5 provide double protection.

In the form shown in Fig. 6, the circuit between the battery wire I! and the wire 96 includes parallel circuits, one being the contacts 93 and 95 of relay 90, the other being the contacts I03 and I05 of a relay I00 having a core I02 surrounded by a coil IOI which is connected with contact I05 and with blade 26 of relay 30. The closing of ignition switch I8 and starter switch 25 causes current to flow from the bate tery to the coil 9| of relay 90 and coil 3I of relay 30; but, during cranking, the contacts 2! and 28 of relay 30 remain closed while contacts 93 and 95 of relay 90 are closed.

In addition to causing the solenoid 35 to complete the starting motor circuit, the closing of contacts 93 and 95 energizes coil IOI of relay I00, causing contacts I03 and I05 to close. The starting motor load on the battery and the risin gen- . tacts 27 and 28 are opened. Once released, re-

lay I 00 cannot be energized until the contacts of relay 90 are closed. Relay 90 will not close .until erator output reduces voltage suificiently to release the contacts of relay almost immediately, the circut being maintained through contacts I03 and I05 which will remain closed until the conengine rotation has practically stopped. Therefore, if the engine makes a false start due to misi ire .or other causes, the relay 30 .is thereby I Opened)? s ii no b cessedtil the engine approaches standstill and the voltage between battery and the generator armature becomes sufficient to operate relay 90. When a normal start is made, relay 30 opens, deenergizing coil IN, and relay I opens, causing crankin to cease. At generator cut-in, the generator armature is connected to the battery in the regulator I and the closing of the starting switch short-circuits the coil SI of relay 90 preventing contacts 93 and 95 from closing. In case the engine has been running and coasts down, the engine starter cannot be operated by pressing the button 25 because battery excitation of coil 3|, acting cumulatively with generator excitation, would cause relay to open its contacts so that coil IOI of relay I00 would not be excited. Coil SI of relay 90 would not be excited because excitation of coil 9| by the battery would be bucked by excitation produced by the generator when separately excited.

Relay 30 is known as a high relay because it operates at relatively high voltage differential between the generator armature terminal and ground. It opens its contacts when the voltage of the generator (self-excited) is slightly above that attained at maximum cranking speed. It closes its contacts at a much lower voltage attained at a very low generator speed at which the corresponding engine speed is below that which will sustain engine operation.

Relay 90 of Fig. 6 is known as a low relay because it operates at a relatively low voltage differential between the generator armature terminal and ground. It is adjusted to close at noload battery voltage or slightly less and to release when battery voltage falls, due to loading of the battery when the starting motor 40 receives current from the battery.

Relay I00 of Fig. 6 is known as the hold-in relay. The closing of relay 90 causes coil IOI of relay I00 to be energized. The closing of contacts I03, I05 of relay I00 causes coil IM to remain energized although the contacts 93, 95 of relay 90 may open. However, once the hold-in relay I00 opens, it cannot be reenergized until battery voltage exceeds generator voltage by an amount sufficient to cause the low relay 90 to close its contacts.

The circuit shown in Fig. 7 is like that of Fig. 6 with the exception that the wire 96 is replaced by 96 which leads to the coil III of a relay IIO surrounding a core I I2 to effect downward movement of spring blade H4 carrying a contact II3 engageable with a contact I I5. When these contacts are closed, the circuit is completed from wire I! to the windings of the solenoid 35.

The circuit shown in Fig. 8 is similar to the circuit shown in Fig. 7. The contacts of relay switches 90 and I00 are in parallel and both together in series with the electromagnet of relay switch H0 and with the contacts of relay 30 and with switch 25. The closing of switch I8 connects the magnet coil 9| of relay 90 with the battery through the magnet coil 3| of relay 30. Relay 90 closes its contacts. The closing of switch 25 causes current to flow from the battery through the closed contacts of relays 30 and 90 to the magnet coils of relays I00 and H0. Relay I00 closes and maintains energization of its magnet coil while relay 90 opens during cranking. The separation of the contacts of relay 30 causes the opening of relays I 00 and H0 and the solenoid switch 35. The relay 30 will not close again until the speed of the engine, having once started, falls far below minimum idling speed. In .case of a false start, relay 30 will not close again until flywheel rotation has practically ceased.

The control circuits shown in Figs. 6, 7 and 8 prevent, on false starts, the startin motor pinion from crashing into mesh with the engine flywheel gear when the engine falters. In a false start, the engine usually fires once or more, opening the high relay 30, then stops, due to misfire or something else. It is possible that the high relay 30 might close at this time and a cycle started Where the pinion was forced to engage and disengage rapidly until the engine became self-operative. However, experience shows that, when the high relay 30 has once opened, it will remain open until cessation of rotation of the engine flywheel.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted, all coming within the scope of the claim which follows.

What is claimed is as follows:

An engine starter control system comprising a generator having a field winding, a storage battery charged by the generator, a device for cranking the engine, a switch for connecting the generator field winding with the battery in order that the generator will be initially separately excited, a cutout relay for connecting the generator with the battery when generator voltage attains a certain value whereby the generator becomes self-exciting at cut-in speed, said relay disconnecting the generator from the battery when generator voltage falls below battery voltage in consequence of which the generator returns to separately excited status, means for causing operation of the engine cranking device, and apparatus for controlling said means and including a normally open relay switch, the closing of which causes the cranking device to operate, said relay switch having an electromagnet for closing it, and including means for connecting said electromagnet with the battery comprising a normally open, manually closed switch and a normally closed relay switch having an electromagnet sensitive to generator voltage for opening it, said second relay switch being so constructed as to remain closed at a generator speed corresponding to maximum cranking speed and to open above maximum cranking speed and below cut-in speed and to reclose at a speed substantially below engine minimum idling speed, and including a short-circuit of the first mentioned electromagnet provided by the closing of the cutout relay whereby cranking ceases at least when the cutout relay closes regardless of failure of the second relay switch to open.

BROOKS H. SHORT. JOHN W. DYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,565,854 Hasselbring Dec. 15, 1925 1,606,532 Hasselbring Nov. 9, 1926 1,631,747 Maby June 7, 1927 1,828,514 Spivey Oct. 20, 1931 1,941,433 Doman Dec. 26, 1933 2,131,026 Doman Sept. 27, 1938 2,131,403 Doehr et al Sept. 27, 1938

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