US2699161A

US2699161A - Control device

Info

Publication number: US2699161A
Application number: US215572A
Authority: US
Inventors: Ronald R Pees
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1951-03-14
Filing date: 1951-03-14
Publication date: 1955-01-11
Anticipated expiration: 1972-01-11

Description

Jan. 11, 1955 R. R. PEES 2,699,161

CONTROL DEVICE Filed March 14, 1951 1N VEN TOR. P004420 9. P555 HIS 14 TTUPN E Y8 United States Patent CONTROL DEVICE Ronald R. Pees, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application March 14, 1951, Serial No. 215,572

4 Claims. (Cl. 123-198) This invention relates to a control device particularly designed for use with diesel engines.

It is among the objects of the present invention to provide a control device for diesel engines effective to stop the engine upon failure of the lubricating system of the engine.

A further object of the present invention is to provide a control device for diesel engines which, if the pressure in the lubricating oil system of the engine fails to reach a predetermined safe value after the engine has operated for a period ordinarly suflicient to have the lubricating oil pressure build up to said value, will automatically stop engine operation.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

The simple view in the drawing illustrates schematically the electric circuits and devices for operating and protecting a diesel engine.

Diesel engines are equipped with means operative to stop the engine. In the present drawing, an air box damper is shown operative by an electromagnet to shut off combustion air to the engine for purposes of stopping it. This air box damper is of the standard design and is applied to the engine in the customary manner. The present drawing diagrammatically shows this damper 20 and its electromagnet coil 21.

Various protective devices are provided on diesel engines which are effective to stop the engine under unusual and what may be damaging circumstances. A diesel engine generally has an overspeed governor which effects operation of the air box damper to stop the engine when its speed exceeds a predetermined rate. A normally open switch is also provided, closable at predetermined temperature of the water in the engine cooling system to effect actuation of the air box damper for stopping the engine to prevent its operation when the cooling water thereof exceeds a certain safe value. Another switch, normally closed, is operative by a predetermined lubricating oil pressure to open and render the air box damper inoperative when a safe lubricating oil pressure is attained. Still another, normally open switch is provided, which is closable by a predetermined fuel oil pressure to complete its portion of the circuit to the air box damper when the fuel oil pressure reaches a predetermined value.

Inasmuch as the present invention is directed primarily to engine protection when failures occur in the lubricating oil system, the overspeed governor and water temperature responsive devices will not be considered.

Ordinarily diesel engines equipped with air box dampers electromagnetically actuated to stop engine operation and lubricating oil and fuel oil pressure switches for controlling the air box damper operate in the following manner.

In starting a diesel engine, the fuel oil pressure switch 25, comprising stationary contacts 26 and 27, connectible in series with the magnet coil 21 of the air box damper 20 is adapted to be bridged and connected together by the movable contact 28. Contact 28 is yieldably urged out of engagement with its cooperating stationary contacts 26 and 27 and is moved to engage them by any suitable means 29 actuated by the fuel oil pressure when it reaches a predetermined value for instance 20 pounds per square inch. The lubricating oil switch 30 is similar to switch 25 but is normally closed so that its stationary contacts 31 and 32 are engaged by the movable, bridging contact 33. When the lubricating oil pressure reaches a predetermined pressure, for instance ten pounds per square inch, element 34 is actuated by said oil pressure to move contact 33 out of engagement with its cooperating contacts 31 and 32 and thus open the circuit through the electromagnet 21 of the air box damper 20 with which contact 31 is connected.

As shown in the drawing, contact 32 is connected with contact 27 and contact 26 with one side of battery 40, the other side of the battery being connected with the air box damper coil or magnet winding 21.

In a diesel engine so equipped, switch 25 generally closes at substantially twenty p. s. i. fuel oil pressure and switch 30 at substantially ten p. s. i. lubricating oil pressure. Switch 30 is closed when the lubricating oil pres sure is less than the predetermined safe minimum and thus with switch 25 closed by the predetermined fuel oil pressure, the circuit through the air box damper magnet winding 21 is completed, causing energization of said magnet winding and operation of the air box damper to stop engine operation due to a dangerously low lubricating oil pressure.

Under certain conditions, the fuel oil pressure reaches its required twenty p. s. i. to close switch 25 before the lubricating oil pressure builds up to the required ten p. s. i. to open switch 30. In this instance, with both

switches

25 and 30 closed, the air box damper circuit is completed and the air box damper thus activated to stop the engine prematurely, inasmuch as the lubricating oil pressure, although building up slowly, did not reach its required value to open switch 30 before the air box damper became effective to stop the engine. Such operation is unsatisfactory, especially if occurring repeatedly, for safe engine operation may obtain as long as the lubricating oil pressure build-up does not require excessively long engine operation.

The present invention eliminates this premature engine stoppage, due to slow build-up of lubricating oil pressure by providing a time delay relay or circuit controller 50 in the circuit of the electromagnet 21 of the air box damper 20. This relay 50 consists of a pivoted frame 51 to which the magnet winding 21 is electrically connected said frame being pivoted to the stationary pin 51a. One end of a thermoelectric element 52 is electrically and mechanically attached to a protruding ear 53 of the frame 51, the other end of said element being attached to an adjustable nut 54 carried by an insulated bracket of the relay. Nut 54 is electrically connected to the contact 31 of switch 30, thus connecting the thermoelectric element in series with the magnet winding 21 of the air box damper 20 and switch 30. Element 52 is of sufficient resistance to current flow that it retards or substantially prevents energization of the magnet winding 21 when its circuit is completed through said element 52. Another characteristic of element 52 is that when cold, or particularly when not heated by current flow therethrough, it contracts and exerts a tension upon the frame portion 53 to move the frame counterclockwise as regards the drawing against the counteracting effort of spring 55 to move the frame 51 clockwise about the pivot pin 51a.

Frame 51 supports a resilient blade 56 at one end, the other end of said blade extending beyond the end of the frame and carrying a contact element 57 which is adapted to cooperate with stationary contact 58 also electrically connected to contact 31 of switch 30. An insulated stop 59 is engageable by blade 56 when contact 57 is held out of engagement with its cooperating contact 58. This occurs when element 52 predominates, being contracted and overcoming the turning effect of spring 55 to cause contact engagement. A resilient finger 60 has one end attached to or formed integral with the blade 56 adjacent contact 57, said finger being biased when its other end is seated in the V-shaped notch 61 in the end edge of frame 51.

When on the one side of blade 56 as shown in the drawing, the seating point of finger 60 with the V-notch 61 of frame 51 causes the bias of the finger 60 to urge blade 56 into resting engagement with stop 59. This is under the influence of the retracted and dominating thermoelectric element 52. When said element is heated and expands due to a. continued current flow therethrough, the spring 55 becomes effective to move frame 51 clockwise about its pivotal support thereby shifting the seating contact of finger 60 with notch 61 of lever 57 to the opposite side of blade 56 so that the biasing effect of the finger 60 upon blade 56 is reversed, the blade being shifted from engagement with stop 59 into the position in which contact 57 on the blade engages contact 58 connected to switch 30. This establishes a shunt circuit about element 52 and thereby removes the coil 21 impeding resistance from the circuit through said coil, permitting energization of said coil 21 and operation of the air box damper 20 to stop the engine, provided both

switches

25 and 30 are closed.

Thus the unsatisfactory condition resulting from the usual equipment and involving repeated engine stoppage due to abnormally slow build-up of the lubricating oil pressure after the engine has started to operate is avoided, for the time delay relay lengthens engine operation under these conditions to a safe maximum, providing an additional interval for the lubricating oil pressure to build up to the predetermined value and open the switch 30 to render the engine stopping device ineffective without endangering the engine. This additional interval is equal to the time required for element 52 to become sufficiently heated and consequently expand sufficiently as to permit the spring 55 to become effective and cause closing of t the substantially unresisting current flow shunt circuit across

contacts

57 and 58 thereby to render the air box damper active.

In case of complete lubricating oil pressure failure, switch closes and completes its circuit connection. The extra interval provided by the time delay relay as aforedescribed would not extend operation of the engine beyond a safe limit even in case of complete failure of lubricating oil pressure.

From the aforegoing it may be seen that the present invention provides a control and protective device for a diesel engine, said device maintaining engine operation for a safe interval to give an abnormally slow lubricating oil pressure build up an opportunity to reach its predetermined value during the lengthened safe operation of the engine, failure of the lubricating oil pressure to reach said predetermined value during engine operation resulting in action by the relay to energize the engine stopping device and render it effective to stop the engine before lack of lubricating oil pressure may cause damage.

While the embodiment of the present invention as hereis disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted. W

What is claimed is as follows:

1. In a control device for an internal combustion engine having fuel and lubricating oil pressure lines and an electromagnetically actuated device for stopping the engine, the combination with an electric power circuit connected to said device, of separate and independently acting switch means in said power circuit, one of said means being normally open and operative for completing said circuit in response to a predetermined pressure in the fuel line and the other being normally closed and operative for opening said circuit in response to a predetermined pressure in the lubricating oil line; and a relay operative only when said other means is closed, said relay having a thermoelectric element connected in the power line between said other means and said device providing electrical resistance therein to prevent energization of the engine stopping device connected in the power circuit therewith, said relay having another electrical conducting element normally disconnected from the power circuit but operative to establish a shunt circuit around said thermoelectric element in response to action of said thermoelectric element due to current flow therethrough for a predetermined interval, whereby the resistance of the thermoelectric element is circumvented and the said device is energized through the shunt circuit to effect stopping of the engine.

2. In a control device for an internal combustion engine having fuel and lubricating oil pressure lines and an electromagnetically actuated device for stopping the engine, the combination with an electric power circuit connected to said device, of normally open control means in said power circuit operative for completing said circuit in response to a predetermined pressure in the fuel line and normally closed control means operative for opening said circuit in response to a predetermined pressure in the lubricating oil line; and a time delay circuit controlling device in the power circuit with the aforesaid control means, said control device having dual current flow circuit means comprising a thermo-electric element in the power circuit effecting suflicient electrical resistance to prevent the energization of the engine stopping device and after a predetermined interval of current flow therethrough effecting closing of the other normally open means in said control device to establish therethrough a substantially unresisted current flow through the power circuit around the said element whereby to energize the engine stopping means to stop the engine.

3. in a control device for an internal combustion engine having fuel and lubricating oil pressure lines and an electromagnctically actuated device for stopping the engine, the combination with an electric power circuit connected to said device, of two pressure actuated switches connected in series in said power circuit, the first of said switches being normally open, but operative at a predetermined pressure in the fuel line, to close the circuit, the second being normally closed, but operative at a predetermined pressure in the lubricating oil line to open the power circuit; and a time delay relay including a resistance element in series connection in the power circuit between said second switch and said device to prevent energization of the electromagnetically actuated engine stopping device when both of said pressure actuated switches are closed, and a normally open circuit control means electrically in parallel with the resistance element and actuated thereby after a predetermined interval of current flow therethrough to effect closing of said control means to shunt the resistance element and thereby effect energization of the engine stopping device.

4. In a control device for an internal combustion engine having fuel and lubricating oil pressure lines and an electromagnetically actuated device for stopping the engine, the combination with an electric power circuit connected to said device, of two pressure actuated switches connected in series in said power circuit, the first of said switches being normally open, but operative at a predetermined pressure in the fuel line, to close the circuit, the second being normally closed, but operative at a predetermined pressure in the lubricating oil line to open the power circuit; and a time delay relay including two parallel circuits in the power line, the first, through a thermo-electric element in the circuit of the engine stopping device and of sufldcient resistance to prevent the energization of said device, the second, through two normally disengaged contacts operative under the effect of expansion of the thermoelectric element after a predetermined interval of current flow therethrough, to establish a substantially unrestricted flow of current through the engine stopping device to render it active when both pressure actuated switches are closed.

References Cited in the file of this patent UNITED STATES PATENTS 2,010,960 Porque Aug. 13, 1935 2,061,164 McNeil Nov. 17, 1936 2,210,044 Schirokauer Aug. 6, 1940 2,373,735 Alexander Apr. 17, 1945 2,410,998 Reavis Nov. 12, 1946 2,418,235 Menzies Apr. 1, 1947 2,423,728 Ray July 8, 1947 2,428,095 Reavis Sept. 30, 1947 2,428,909 Werner Mar. 2, 1948 2,565,984 Newman et al Aug. 28, 1951