US2265755A

US2265755A - Cranking time limiter

Info

Publication number: US2265755A
Application number: US313764A
Authority: US
Inventors: Manuel H Elkin; Frank T Christian
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1940-01-13
Filing date: 1940-01-13
Publication date: 1941-12-09
Anticipated expiration: 1958-12-09

Description

Dec. 9, 1941.

H. ELKiN ETAL CRANKING TIME LIMITER Filed Jan. 13, 1940 IN VENTOR.

manual/ 0 fibwv Patented Dec. 9, 1941 CRANKING TME LIMITER.

Manuel H. Elkln, Elmira Heights, and Frank T.

Christian, Elmira, N

assignors to Bendix Aviation Corporation, South Bend, Ind., a corporatlon of Delaware Application January 13, 1940, Serial No. 313,764

2 Claims.

The present invention relates to a cranking time limiter for engine starter controls, and more particularly to a thermostatic controlling device for interrupting cranking after a predetermined time interval.

In certain types of engine installations equipped with automatic starter controls, it is desirable to incorporate in the controlling means a device for interrupting the cranking operation after a predetermined time if the engine fails to start for any reason. This is particularly true in cases where the power plant is normally unattended as in isolated installations for beacon lights and the like, and for certain types of air-conditioning units.

In order to conserve the charge of the starting battery as much as possible, such cranking time limiter should become effective after a time interval sufllcient to secure a start under the normal range of operating conditions. Since this normal range may include wide variations in ambient temperatures, battery efllciency, engine stiffness, etc., the time control should be accurate irrespective of such conditions in order to secure consistent operation.

It is an object of the present invention to provide a novel cranking time limiter for internal combustion engines which is accurate and dependable in operation while being simple and economical in construction.

It is another object to provide such a device, the calibration of which is substantially unafiected by usual variations in operating conditions.

It is a further object to provide such a device incorporating a thermostatic controlling device which is positive in action while being susceptible of accurate calibration.

It is another object to provide such a device in which the thermostat operates substantially without sliding friction such as might interfere with the accurate calibration thereof.

It is another object to provide such a device a ing the thermostatic controlling device with its associated elements.

In Fig. 1 of the drawing there is illustrated a starting circuit for an internal combustion engine, not shown, including a. battery I connected by a lead 2 to an automatic controlling device indicated generally by numeral 3. This controlling device is of a well-known commercial form including a magnetic switch 4 which is connected by a lead 5 to a starting motor SM, the starting circuit being completed to the battery through the ground.

A control circuit for the magnetic starting switch 4 is provided including a manual switch 6 connected by lead 1 to battery lead 2 and by a lead 8 to a terminal 9 of thermostatic cranking time limiter indicated generally by numeral ll. Terminal l2 of the cranking time limiter II is connected to the engine ignition system and also through a lead I3 to a backfire circuit controller l4 which is of a commercial type forming no part of the present invention. The circuit controller is connected by a lead I! to the solenoid l6 of the magnetic starting switch 4. Solenoid I6 is connected by lead I! to a contact l8 which is normally in engagement with a contact IS on a pendulously mounted reed 2| which is grounded at 22 to complete the control circuit.

Means for opening contacts IS, IS are provided including a coil 23 which actuates a plunger 24 to move a pivoted lever 25 so that its free end engages the free end of the reed 2| and bends it back away from contact l8. Coil 23 is connected at one end by lead 26 to the starting motor lead 5 and is grounded at its other end as indicated at 21. Means for holding contacts l8, I9 open is provided in the form of a coil 28 also grounded at 21 and connected by a lead 29 to a vacuum operated switch 3| mounted on the intake manifold 32 of the engine and having contacts closed by the vacuum in .the intake while the engine is running. The switch 3| is connected by lead 33 to terminal 34 of the thermostatic cranking time limiter l I.

As illustrated in Fig. 2, the cranking time limiter comprises a housing 35 having a partition 38 fixed therein dividing it into an upper chamber 31 and a lower chamber 38. A bracket 39 is fixedly mounted on the partition 36, and a bimetallic plate 4i is rigidly fixed thereto at one end as indicated at 42. A bimetallic arm 43 is fixed at one end to the plate 4| as indicated at 44. the two bimetallic parts being thermally insulated from each other as indicated at 45. The plate 4| is arranged so'that a rise in temperature thereof will cause it to bend upward, while the arm as is reversely arranged so that when heated it bends downward. A heating coil 36 for the thermostatic arm as is grounded at one end thereon as shown atil and is connected by a lead it to a current regulating device in the form of a ballast tube as mounted in the lower chamber 36 or the housing 35. The ballast tube is connected by a lead 59 to terminal 52 of the cranking time limiter which, as shown in Fig. l, is connected by a lead 53 to the starting motor lead 5.

A flexible yoke member 55 is mounted fixedly on the partition 3% while being insulated therefrom as shown at 57. The yoke 56 is arranged to extend around the thermostatic arm 33, the anchorage 5? for the yoke being located adjacent the bracket 39. The crosspiece 53 of the yoke carries a contact 59 which is normally in engagement with a fixed contact ti connected by a lead 62 to the terminal 32' of the cranking time limiter. Yoke 56 is connected by a lead 83 to the terminal 9 of the cranking time limiter.

Means for operating the yoke 56 to open contacts til, 65 by the action of the thermostatic arm :33 is provided in the form of a compression connection between the end of the thermostatic arm and the crosspiece 58 of the yoke. as here shown, this connection is in the form of a compression spring 66, the ends of which are seated in socket members t5 and 65 which are formed to have rocking engagement with the end of the thermostatic arm 33 and the edge of the crosspiece 58 respectively. It will be readily under stood that since the spring 6% is under initial compression, it forms in efiect a toggle connection with the thermostatic arm 53, and when said arm bends downward beyond the straight-line position, the spring will move the crosspiece 58 upwardly to open contacts 59, ti with a rapid snap action.

A contact ti! on an insulated bracket 68 is provided to act as a stop for contact 5% and is connected by a lead iii to a terminal t9 which, as shown in Fig. l, is connected by a lead ii to an alarm device 52.

Terminals 9 and ii are connected by a resistor 33 of suitable value to reduce the current flowing through the coil 28 to a value just sumcient to reliably hold the plunger 26 in its attracted position so as to maintain contacts i8, 59 open.

Means for adjusting the thermostatic arm 33 by flexing the bracket 39 is provided in the form of an adjusting screw it tapped into the parti-- tion 38. Manual means for returning the yoke 58 to normal position is provided in the form of a plunger l5 slidably mounted in the side of the casing 59 and a bracket it, and having a conical point ll adaptedto engage the crosspiece 58 to move it to its lower position. A spring i8 is preferably provided for normally maintaining the plunger it out of the path of movement of the crosspiece 58.

In operation, closure of the manual switch t completes a circuit from the battery 6 through leads V and 8 to terminal 55 of the cranking time limiter. Since contacts 5t, ti are normally closed, current flows through lead 63, yoke 5%, contacts bi, ti and lead 2 to terminal 62 from whence it flows through lead 63, circuit controller id and lead i 5 to the solenoid it, and from thence through lead ii and contacts i3, i9 to the ground at 22. Magnetic starting switch 5 is thereby closed, completing the starting circuit from battery l through leads 2 and 5 to the starting motor to initiate the cranking operation. Closure of the starting switch 4 causes energization of the coil 23 or the starter control 3, but attraction of the plunger 2% thereby is resisted by a single turn coil it in the cranking circuit which prevents opening of contacts 98 and it during the cranking operation. If the engine starts properly, the weakening of the starting circuit by the release of the cranking load from the starting motor perunits the coil '23 to overcome the effect of the single turn coil l9. whereupon the plunger 24 is attracted to cause opening of contacts it, it, thus breaking the control circuitof the solenoid i6 and thereby permitting the starting switch 5 to open. Thereafter contacts 58, it are held open by the energization of coil 28 which isenergized from the battery through leads l and 8, terminal 9, resistor 73, terminal 34, lead 33, vacuum switch 3i and lead 29.

During the cranking operation, closure of starting switch 1 also completes the heating circuit for the thermostatic arm 63, which circuit includes battery lead 2, starting motor lead 5, lead 53, terminal 552, lead 51, ballast tube 59, lead 68, heating coil 65 and ground connection ii. The thermostatic arm #33 is thus caused to be heated during the cranking operation a rate held substantially constant by the ballast tube 19, and if the engine fails to start after a predetermined time interval. the thermostatic, arm bends downward suiiiciently to open contacts t9, 6!, thus interrupting the control circuit for the magnetic starting switch it and causing the cranking operation to cease. At the same time,

contacts

59, 67 are closed. completing a circuit through lead iii, terminal it and lead ii to the alarm device 72.

Variations in the operation of the thermostat due to changes in ambient temperatures are prevented by means of the thermostatic plate ii which serves as a mount for the thermostatic arm 33 and which, as above stated, is reversely arranged in respect thereto. In other words, a rise in ambient temperature which causes the arm 33 to bend downward, will cause the plate ti to bend upward to a properly corresponding degree. Substantially uniform action of the thermostatic arm 63 is thus secured.

When an attendant summoned by the alarm device has removed the inoperative condition of the engine so as to make it possible to start, it is merely necessary for him to actuate the plunger it: to return the thermostatic contacts to normal position, whereupon the cranking operation will be resumed in the usual manner.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

1. In a cranking time limiter for internal combustion engines, a control circuit including a fixed contact, a flexible U-shaped yoke member anchored atv its open end and carrying a contact on its closed end movable by fiexure of the yoke member into and out of engagement with the fixed contact, a thermostatic arm anchored at one end adjacent the anchorage of the yoke and extending into the yoke toward its free end, a spring interposed under pressure between the free ends of the arm and yoke to form a snapmember anchored to the housing adjacent the bracket in position to surround the thermostatic arm, a compression spring between the end of the arm and the yoke, a fixed contact, a contact on the yoke normally in engagement therewith, means for flexing the bracket to adjust the contacts, and means for heating the thermostatic arm during the cranking operation to cause opening of said contacts after a predetermined time therein, a thermostatic mounting plate fixed at 10 of cranking.

one end on the bracket, an oppositely arranged thermostatic arm fixed to the other end of the plate and insulated therefrom, a flexible yoke MANUEL H. ELKIN; FRANK T. CHRISTIAN.