US2648746A

US2648746A - Engine-function switching mechanism

Info

Publication number: US2648746A
Application number: US96347A
Authority: US
Inventors: John W Dickey
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1949-05-31
Filing date: 1949-05-31
Publication date: 1953-08-11
Anticipated expiration: 1970-08-11

Description

Aug. 11, 1953 J. w. DICKEY 2,648,746

ENGINE-FUNCTION SWITCHING MECHANISM Filed May 51, 1949 3 Sheets-Sheet l 1216 57 FT/ 9 5?- 53 gm 31 55 10 .w

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Aug. 11, 1953 J. w. DICKEY ENGINE-FUNCTION vSWITCHING MECHANISM 3 Sheets-Sheet 2 Filed May 3l 1949 am BY W1TWESS:'. O

TORNEY Patent g- 53 ENGINE-FUNCTION SWITCHING MECHANISM John W. Dickey, Newfield, N.

dix Aviation Corporation,

Delaware Y., assignor to Bena corporation of Application May 31, 1949, Serial N 0. 96,347 3 Claims- (01. 200-153) The present invention relates to an enginefunction switching mechanism and more particularly to a switch mechanism for controlling the actuation of auxiliary apparatus, such as a fuel pump or ignition or starting mechanism, in consonance with the operative condition of the engine.

When an electrically actuated pump is used to supply fuel to an internal combustion engine, it is desirable that the pump and the ignition system be rendered operative only when the engine is operative. Otherwise, if the master control switch, such as the ignition switch of the engine, is left closed in the absence of the operator or in case of accident, the pump may continue to operate so as to constitute a fire hazard. It is also desirable to prevent the actuation of the starting mechanism when the engine is in motion, and many devices have been suggested for utilizing some one or more of the conditions caused by rotation of the engine to actuate switch mechanism for this purpose.

Obviously, the most desirable way to operate such a switch is by some direct mechanical connection to a moving part of the power plant, thus avoiding the delays and uncertainties attendant upon the use of secondary elfects such as intake vacuum or pressure, generator voltage, oil pressure, etc., but such mechanical connections as heretofore proposed have had to be unduly complicated and expensive in order to take care of all necessary conditions of operation.

It is an object of the present invention to provide a novel switch, and mechanism for operating the switch from a rotating part of the I power plant.

It is another object to provide such a device which incorporates a slip coupling for transmitting a suitable small amount of torque to actuate the switch, and a viscous coupling which yields slowly with very little resistance, but which strongly opposes any rapid relative movement of its parts.

It is another object to provide such a device including means for resiliently biasing the switch toward one of its operative positions, the connection from the rotating part of the engine being arranged to overcome the biasing means and hold the switch away from said position as long as the engine is in rotation, the viscous coupling 2 being arranged to slowly yield and allow the resilient means to return the switch to its normal position after the engine stops.

It is another object to provide such a device which is simple in construction, reliable in operation, economical to manufacture, and readily adaptable to existing commercial power units with a minimum of structural change.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a semi-diagrammatic illustration of one preferred form of the invention, the parts being partly broken away and shown in section;

Fig. 2 is a section taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a section taken 3-3 of Fig. 1;

Fig. 4 is a semi-diagrammatic illustration of a form of the invention used as an engine starter control, the mechanical parts being shown in perspective, partly broken away and in section;

Fig. 5 is a diagrammatic illustration of a modified form of starter control;

Fig. 6 is a diagrammatic illustration of a second modified form of starter control;

Fig. 7 is a view similar to Fig. 1 showing an embodiment of the invention used to prevent actuation of the starting mechanism when the engine is rotating backward;

Fig. 8 is a section taken substantially on line 8-8 of Fig. 7;

Fig. 9 is a section taken substantially on the line 9-9 of Fig. 8; and

Fig. 10 is a detail in slip coupling member.

In Fig. 1 of the drawing there is illustrated a portion of an electrical system for an internal combustion engine power unit comprising a battery I Which is grounded at 2 and connected by a manual switch 3, which may be the ignition switch of the engine, not illustrated, through a lead 4 to a control switch indicated generally by numeral 5. Switch 5 comprises

contact members

6 and 7 which are sealed into the bottom of a cup-shaped casing 8 by means of iusable insulating material as indicated at 9 and H. Contact 6 is connected to the battery lead 4, and contact 1 is connected by a lead N to the ignition substantially on line elevation of the driven K1 circuit as indicated by the arrow and legend, and to an electrically operated fuel pump indicated conventionally at l2, and which is grounded at 13 to complete its electrical circuit.

A bridging contact M (Fig. 3) for connecting the fixed contacts 5 and l is yieldably mounted on a lever member l5 as by means of a retaining spring l6. Switch lever I5 is suitably attached, as by soldering, as indicated at 11, to the center of a flexible diaphragm l8 which closes the open end of the switch casing 8. Diaphragm l8 thus forms a pivotal mounting for the lever l5 which permits it to swing and thereby move the bridging contact l4 into and out of engagement with the

fixed contacts

6 and 1.

The switch casing 8 is rigidly mounted as by soldering, as indicated at [9, in a housing member 2| which is attached as indicated at 22 to the end of the frame 23 of the engine driven generator indicated generally by numeral 24. Itwill be understood that any rotatable part which is driven by or rotates with the engine may be used to actuate the control switch 5. In commercial forms of power units it is usually most convenient to utilize the armature shaft of the generator as the control means since it is readily accessible by merely removing the end cap of the generator and substituting therefor the new end cap or housing 2| carrying the control switch 5. According to the present invention, therefore, means are provided for actuating the control switch 5 so that it occupies one operative position when the armature shaft 25 of the generator 24 is rotating, and is moved to another operative position after said armature shaft is stopped.

In the present instance, since the switch 5 is used to control the ignition circuit and the fuel pump of the power plant, it is desired that said switch be normally open, but closed during rotation of the engine. For this purpose, a resilient spring 26 is mounted as shown at 2'! in the housing 2|, and is connected as shown at 28 to the end of the switch lever l5 so as to apply pressure thereto in a direction to move the switch 5 to open position. Means for closing the switch 5 responsive to rotation of the generator armature shaft 25 is provided comprising a slip coupling which is adapted to transmit a substantially constant small amount of torque while slipping, and a viscous coupling which is arranged to permit slow relative movement of its parts, but to strongly resist any rapid relative movement thereof. The slip coupling comprises a disc 29 of suitable material such as oilite or nylon, which is rigidly mounted on a shaft 3! and pressed against the end of the armature shaft 25 by means of a spring 32 mounted as shown at 53 in the housing 2|. The viscous coupling comprises a second disc member 35 fixedly mounted on the outer end of the shaft 3!, and enclosed in a casing or capsule member 35 which is journalled on the shaft 3| and provides a closed annular chamber 36 surrounding the driving disc 34. The space or chamber 36 is at least partially filled with a suitable highly viscous material which forms a slowly yielding connection between the driving member 3 and the housing 35 which thus becomes the driven member of the viscous coupling. The material which has been found most suitable for this slowly yielding connection is that type of silicone product known as bouncing putty, which has recently become available for commercial use. This material flows by its own weight at a very slow speed, but is extremely resistant to any sudden deformation, these qualities being retained substantially constant over a very wide temperature range.

It will be understood that when the term viscous coupling is used in the specification and claims, it is intended to designate a coupling such as herein described which constitutes substantially a rigid connection as respects any rapid relative movement of the parts but which opposes very little resistance to a slow and gradual relative displacement thereof.

The driven viscous coupling member or housing 35 has rigidly mounted thereon in any suitable manner a crank member H, which as shown in Fig. 2 is provided with a slot 35 slidably receiving the switch lever is so that rotation of the generator shaft 25 in a counter-clockwise direction as viewed in Fig. 2, will swing the switch lever :5 against the action of the spring 26 to close the switch 5.

In the operation of this embodiment of the invention, and starting with the parts in normal position with switch 5 held open by the spring 25, the operator closes the ignition switch 5 and causes actuation of the starting mechanism of the engine, which thereby causes the armature shaft 25 of the generator 25 to rotate in a counter-clockwise direction as shown in Fig. 2. this rotation causes a torque to be applied to the coupling member 29 by its frictional engagement with the end of the armature shaft, which torque is transmitted through shaft 31 to the driving disc 3 and through the viscous material in the chamber 35 to the driven coupling member 35 and crank 31. The force so applied by the crank 31 to the switch lever 25 overcomes the force of the spring 25 and moves the bridging contact [A into engagement with the

fixed contacts

6, 1 whereby the ignition circuit and the fuel pump circuit are completed, and these circuits are maintained closed throughout the subsequent operation of the power plant. If the engine should stop for any reason, as for instance in case of collision or upset of a vehicle containing the power plant, the shaft 25 stops and spring 26 then becomes effective to slowly rotate the driven viscous coupling member 35 backward against the resistance of the viscous material therein, opening the switch 5 after a suitably short time delay and thus rendering the ignition circuit and fuel pump inoperative.

In Figs. 4, 5 and 6 a switch mechanism similar to that above described is used to control the starting operation so as to prevent an inadvertent actuation of the starter while the engine is running. As illustrated in Fig. 4, the electical system comprises a battery All grounded at 42 and connected by a lead 43 to a manual switch 44. Switch 44 is connected by a lead 45 to a control switch indicated generally by numeral 50 which is connected by a lead 5! to the coil 52 of an electromagnetic starting switch 53, said coil being grounded at 55 to complete the control circuit. Starting switch 53 is connected by a lead 55 to the battery lead 43 and by a lead 56 to the starting motor SM which is grounded at 51 to complete the starting circuit. Control switch 50 is in all respects constructed and operated similarly to the control switch 5 in Figs. 1 to 3 and the parts thereof are accordingly similarly numbered. In this case, however, the control switch 50 is positioned reversely as compared to the switch 5 so that the switch 55 is normally held closed by the spring 25, and is opened by the rotation of the generator shaft 25.

Means are provided in shunt with the switch 50 for transmitting sufiicient current to the starting switch to hold it closed after the control switch 50 opens, as long as the manual switch 44 is held closed. As shown in Fig. 4, this means is in the form of a resistor 58 connecting the leads 45 and 5| and having such a value that it passes suflicient current to cause the coil 52 to hold the starting switch 53 closed, but does not energize said coil sufliciently to cause closure of the starting switch.

In Fig. 5 of the drawing a similar result is secured by means of an auxiliary switch 60 which is shunted across the control switch 50 and which is mechanically connected to the starting switch 53 so as to be closed concurrently therewith. In Fig. 6 the same function is accomplished by means of a relay 6|, the coil 62 of which is in series with the starting switch coil 52 and the contacts 63 of which are shunted across the control switch 50. The remaining parts of the systems illustrated in Figs. 5 and 6 are thesame as shown in Fig. 4 and are similarly numbered.

In the operation of this device as a starter control, as here illustrated, closure of the manual switch 44 while the engine is stationary completes a circuit through the control switch 50 and coil 52, causing closure of the starting switch 53 whereby the starting motor SM is energized to crank the engine. The consequent rotation of the generator shaft 25 causes torque to be transmitted through the slip coupling member 29 and the

viscous coupling

34, 35, 36 to switch lever I5 which overcomes the spring 26 and opens the control switch 50. Cranking is not interrupted, however, since the current traversing the resistor 58 maintains the cranking circuit closed until such time as the manual switch 44 is opened. Thereafter, inadvertent closure of the manual switch 44 is prevented from actuating the starting mechanism since the control switch 50 is held open as long as the engine is running. Should the engine stop, closure of the manual switch 44 by the operator will again actuate the starting mechanism after a predetermined time delay provided by the gradual yielding of the

viscous coupling

34, 35, 36 under the pressure of the spring 26 which closes the control switch 50.

In Fig. 5, the shunt switch 60, and in Fig. 6 the relay 6I with its shunt contacts 63 perform the same function as the resistor 58 in Fig. 4 in preventing interruption of cranking until after the manual switch 44 has been opened.

In Figs. 7 to 10 inclusive an embodiment of the invention is illustrated which provides means for preventing actuation of the starting system when the engine to be started is rotating backward.

As shown in Fig. 7, the starting system comprises a battery 1I grounded at 12 and connected by a lead 13 to a manual switch 14 which in turn is connected by a lead 15 to a control switch 80 which is similar in all respects to the control switch 50 illustrated in Fig. 4, except that it is arranged to be opened in response to backward rotation of the generator shaft 25. Control switch 80 is connected by a lead 8| to the coil 82 of the electromagnetic starting switch 83, coil 82 being grounded at 84 to complete the control circuit. Startin switch 83 is connected by a lead 85 to the battery lead 73 and by a lead 86 to the starting motor SM which is grounded at 81 to complete the starting circuit.

In this embodiment of the invention there is shown a modified arrangement of slip coupling and viscous coupling whereby any misalignment or vibratory movement of the generator shaft is prevented from affecting the connection to the switch lever I5. As here shown, a disc I 00 of suitable friction material is pressed against the end of the shaft 25 by means of an H-shaped spring member IOI (Fig. 9) which bears against a diaphragm member I02 pressed into a housing support I03 fixedly mounted on the. generator casing I04. A shaft I 05 journalled in the diaphragm member I02 and in a support bracket I06 is coupled to the friction disc I00 by means of a cross pin I01 with freedom for some universal movement. Shaft I05 carries a driving disc I08 which is coupled to a driven housing I09 by means of the viscous material I II contained therein and surrounding the disc member I08. Driven housing I09 is journalled on the shaft I05 and carries a crank member II2 which engages the switch actuating lever I5. Switch is normally held closed by a spring member H3 attached as indicated at II4 to the switch lever I5, and anchored to a spacing and positioning member II5 of insulating material pressed on fixed

contact members

6 and 1.

In the operation of this embodiment of the invention closure of the manual switch 14 when the engine is stationary causes energization of the starting system since the control switch 80 is at that time closed. Forward rotation of the generator shaft 25 has no effect on the control circuit since the switch 80 remains closed and cranking continues until the engine starts and the manual switch 14 is opened. If, however, the manual switch is inadvertently closed at a time when the engine is rotating backward the control circuit for the starting system will not be closed since switch 80 has been opened by the backward rotation of the generator shaft 25 which transmits torque through the slip coupling member I00 and the viscous coupling I 05, I 09, III to the switch lever I 5. The switch 80 is thereby held open as long as the backward rotation of the engine persists. When the engine stops, the spring II3 becomes eifective to close the control switch 80 after a predetermined time delay dependent upon the viscosity of the material II I. Thereafter, closure of the manual switch 14 eifects actuation of the starting system in the usual manner.

Although certain embodiments of the invention have been described in detail, it will be understood that other embodiments are possible and that various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In combination with a rotatable member of a power unit, a switch comprising a part moveable to two operative positions, yielding means urging said switch part to one operative position, and a connection for transmitting torque from said rotatable member to said switch part to move it away from said one operative position, said connection including a slip coupling comprising a drag member having a smooth surface bearing on a similar surface of said rotatable member and yielding means pressing said surfaces into frictional contact to transmit a substantially constant torque while slipping irrespective to the relative speed of its parts; and a viscou coupling comprising a driving member rigidly connected to said drag member, a driven member spaced from the driving member and a semi-solid slow-flowing adhesive material occupying the space between said driving and driven members.

2. The combination set forth in claim 1 in which the driving part of the viscous coupling is inthe form of a disc, the driven part is in the form of a chamber enclosing the disc, and the fluid medium is of the nature of bouncing putty, at least partially filling said chamber, and adhermg to the surfaces of the chamber and disc.

3. The combination set forth in claim 1 in which the yielding means acting on the switch part is in the form of a spring, and the slip coupling is arranged to transmit While slipping sufficient torque to overcome said spring and move the switch part.

JOHN W. DICKEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Simon June 15, 1915 Holt Mar. 21, 1922 Murdock Sept. 9, 1924 Christen Feb. 13, 1934 Arthur Dec. 29, 1936 Berry Feb. 16, 1943 Robbins Nov. 21, 1944 Mershon Mar. 21, 1950,