US2518400A - Safety means for internalcombustion engines - Google Patents

Description

1950 L. D. THOMPSON 2,518,400

SAFETY MEANSFOR INTERNAL-COMBUSTION ENGINES Filed July 23, 1948 ATTORNEY Patented Aug. 8, 1950 SAFETY-MEANS For. INTERNAL-- COMBUSTION ENGINES Lionel 1). Thompson, Beloit, Wis., assignor to.

Fairbanks, Morse & 00., Chicago, 111. a corporation of Illinois Application uly 23, 1948; Serial No. 40,228

. 1 This invention relates to safety means for internal combustion engines, and is particularly concerned with means for insuring safe opera-- tion of dual fuel engines.

The subject of this invention is closely related with the type of dual fuel engine shown and described in a prior application for patent of Clarence H. Schowalter, filed January 11, 1947,.

and bearing Serial No. 721,549. In that application a control, system for dual fuel engines has been described. In its essential disclosure, the

engine is provided with a liquid fuel pump having a source of supply under at least a predetermined minimum head pressure to assure an adequate feed. There is also a gaseous fuel supply conduit in which a control valve islocated, the valve being constantly biased in a closing direction and being operated to an open position by means of a motor device which is associated with engine control system. This latter control system is arranged to permit engine operation on liquid fuel alone or on gaseous fuel with a reduced charge of the liquid fuel supplied to the combustion chamber for purposes of initiating the proper combustion of the gaseous fuel. A more complete knowledge of the engine operation may be had by reference to this prior application.

The present invention has as its principal object the provision of safety means functionally related with the liquid and gaseous fuel supply systems of the engine so that an improper sup- 1 7 Claims. ((21. 123-27),

engine, with the present safety device shown in sectional elevation.

In the drawing, the engine is represented as of two-cycle Diesel typ having a cylinder J3 provided with suitable air inlet and scavenging ports controlled by the piston I!) connected to a crankshaft in the usual manner. The cylinder head structure 2! is formed to receive a liquid fuel injection nozzle 22, a gaseous fuel admission valve 23 and an air starting valve 24. The air start valve 24 forms no part of this invention and has been shown in fragmentary part only. The gaseous fuel valve 23 is conventionally operated through an engine driven cam 25 and cooperating push rod 26 and rocker 21, the latter being carried by a suitable bracket 28.

The liquid fuel supply system for the engine comprises a supply header 29 receiving the fuel from a suitable source (not shown) under a preply .in one of the liquid fuel systems will cause a shut-down in the supply from the gaseous fuel system and result in stoppage of the engine before any great amount of gaseous fuel can accumulate in the engine or its exhaust manifold to create a dangerous and explosive residual charge.

It is also an object of this invention to provide a simple, positive operating safety device for dual fuel engines which is responsive solely to a pressure drop of a predetermined order in the liquid supply system for effecting a stoppage of the engine by interrupting the supply of fuel from the gaseous fuel supply system, it being particularlydetermined minimum head pressure which will provide for an adequate supply to the inlet line 30 of a fuel pump 3!. The pump 3| is connected to the injection nozzle 22 by the high pressure feed line 32. Pump 3| is provided with a control member 38 for effecting variations in the fuel delivery, and member 33 is longitudinally displaced under the control influence of an angularly movable lever system 34. The member 33 is spring urged against the lever system 34 and rotates the usual pump displacement piston (not shown) after the manner of the'well known Bosch type pump. Lever system 34 includes a principal arm 35 fixed on the control shaft,

' schematically represented by the dashed line 36,

ondary arm ,31 is independently pivoted but is,

cam controlled to assume a setting capable of maintaining the pump member 33 at its minimum fuel delivery or pilot fuel injection setting. This pump control is more fully discussed in the prior application for patent of Clarence H. Schowalter. Control shaft 36 is rotated in response to the action of a governor 38 during the period when the arm 35 is effective to regulate pump delivery in accordance with the governor speed response. It should be understood that the pump 3| and its associated control lever system 34 is shown herein by way of example only, and

-that other types of fuel pumps can be substituted therefor without affecting the intended results.

The gaseous fuel supply system for the engine includes a gaseous fuel conduit 43 connected to a valve chest ll, and a header l2 leading from the chest 4| to a branch line 43 which, in turn,

opens into the cylinder head 2| adjacent the gaseous fuel admission valve 28. The valve chest 4| contains a valve 44 which is subject to the control action of the governor 38 through the control shaft 36. Conduit 46 is equipped with a control valve 45 in which the valve element 46 is constantly urged in a closing direction by a spring element 41, and is operated in an opening direction by motor means 48.

The motor means 48 constitutes one part of a releasable holding means or system Operatively associated with the control valve 45. This system includes a manual control cam 58 regulating the position of the plunger in a master relay 52, a responsive relay 53 having a plunger 54 which is responsive to an engine over-speed governor device 55 through a mechanical lever system 56, a system of fluid pressure and drain pipes, and an engine driven pump 51. The pump 5'! draws hydraulic fluid from the sump 58 and delivers it into line 58 leading to the upper zone of the master relay 52. From the latter relay a drain line 60 extends to the sump 58, and a pressure line 6| leads to the safety device, generally indicated at 62. From the device 62 a pressure line 63 leads to the responsive relay 53, and a line 64 connects between the relay 53 and the motor means 48. Relay 53 is provided with a normally closed drain line 65 (as shown) which connects into a second drain line 66, the latter drain extending between the device 62 and sump 58.

The safety device 62 comprises a cylindrical housing 68, a plunger element 69 slidably disposed in the housing to define an annular chamber between its opposite pistons 1| and 12, a spring 13 and retainer cap 14, and a tappet element slidably disposed in the end of the housing 68 opposite the spring 13. Operatively associated with the device 62 is a piston and cylinder assembly 16. This assembly has its cylinder 11 axially aligned with the housing 68 so that a slidable tappet element 18 is conditioned to engage the head of tappet 15. The tappet 18 is actuated by a piston element 19 cagedjn the cylinder 11 by the cap 88. Assembly I6 is connected by a pressure line 8| in the cap 80 with the liquid fuel supply header 28 so that the piston 18 is constantly subject to the predetermined minimum pressure and is urged to the position shown. In such position, the plunger 69 of the device 62 is displaced against its spring 13 so that the upper piston ll uncovers fluid pressure line 6| and the lower piston element I2 covers the drain line 66. So long as the predetermined minimum supply pressure prevails in the liquid fuel header 29, the device 62 will be held in the setting shown, since this pressure is sufficient to overpower the loading spring I3. Any decrease of this pressure will immediately allow spring I3 to overpower the piston 19 and displace the plunger 69 so that line 6| will be closed and drain 66 will be opened. The line 63 to relay 53 will not be afiected and consequently may act as a drain line from the motor means 48 to release the same for valve closing action by its spring 41.-

In the drawing, the system has been shown at engine starting with the pump 3| delivering liquid fuel and the master relay 52 conditioned by the control cam 50 to prevent opening of the gaseous fuel control valve 45. At this time, it will be noted that the safety device has attained its proper setting so as not to interrupt fluid pressure actuation of the motor means 48. When it is desired to operate the engine as a dual fuel engine, the control cam 50 is rotated counter clockwise 90 degrees to bring the low zone 82 of the cam over the master relay plunger 5| and enable the plunger to rise under the spring load thereon. Theplunger II will close drain line and connect the pressure line 58 with line 6'! so that fluid pressure is transmitted to the chamber 10 of device 62 and into line 63. Relay 53, being held by the overspeed governor 55 as shown, will permit the pressure to act on the motor means 48 in a direction to open the control valve 45 in the gaseous fuel supply conduit 40. Thus the conversion to dual fuel operation of the engine is completed, and the governor 38 will regulate valve 44 in the valve chest 4| to supply gaseous fuel as required. At the same time the secondary lever 31 at the fuelpump will assume control thereof to maintain the proper supply of the liquid fuel for pilot ignition purposes.

Should the liquid fuel header pressure drop below the minimum desired, the spring 13 in the safety device 62 will immediately overpower the piston 18 and displace the plunger 68 to interrupt the fluid pressure line 6| and open drain line 66. This latter action releases the valve motor means 48 by draining away the pressure fiuid through the relay 53, line 63, and chamber 10, to line 66. Once released, the spring 41 immediately closes the control valve 46 and prevents further supply of the gaseous fuel. In this manner, the engine is prevented from accumulating a quantity of combustible matter in the exhaust manifold which could become explosively dangerous at the next starting attempt.

Only a single form of the invention has been shown and described, but it should be understood that changes, and substitution of parts and elements may be made herein without departing from the spirit and full intended scope of the invention as defined by the following claims.

I claim:

1. In a. dual fuel internal combustion engine, a gaseous fuel inlet conduit, a normally closed valve controlling the conduit, a liquid fuelpump connected to the engine and supplied with liquid fuel under at least a minimum head pressure, means for releasably holding said valve open'to supply gaseous fuel during normal dual fuel operation of the engine, and a device responsive to liquid fuel supply head pressure for rendering said releasable holding means effective to open said valve, said device being immediately operable upon liquid fuel supply head pressure drop below the minimum to release said holding means and permit valve closure.

2. In a duel fuel internal combustion engine, a gaseous fuel inlet conduit, a valve controlling said conduit, means constantly urging said valve to close the conduit, a liquid fuel pump connected to the engine and supplied with liquid fuel at a minimum predetermined head pressure, means for releasably holding said valve open to supply gaseous fuel during normal dual fuel operation of the engine, and -a device responsive to liquid fuel head pressure for rendering said releasable holding means effective toopen said valve, said device being operable upon a reduction of the minimum liquid fuel supply head pressure to release said holding means and permit valve closure by said urging means.

3. In a duel fuel internal combustion engine,

a liquid fuel pump connected to the engine and supplied with liquid fuel under at least a minimum pressure, a conduit connected with the engine for supplying a different fuel thereto, a valve controlling said conduit, means for releasably holding said valve open to supply fuel durfuel supply for rendering said releasable holding means effective to open said valve, said responsive means being operable upon a liquid fuel supply pressure drop below said minimum to release said holding means, and means immediately operable upon release of said holding means to close said valve.

4. In a duel fuel internal combustion engine, a liquid fuel pump connected to the engine and supplied with liquid fuel under at least a minimum pressure, a conduit connected with the engine for supplying a different fuel thereto, a conduit control valve normally closing the conduit, fluid pressure holding means for maintaining said valve open during normal dual fuel operation of the engine, means responsive-to liquid fuel supply pressure for rendering said holding means effective to open said valve, said responsive means being operable upon a decrease in the minimum fuel supply pressure to release said holding means and enable valve closure of said conduit.

5. In an internal combustion engine, a fuel pump connected with the engine and supplied 7 with a liquid fuel, a'conduit connected with the engine for supplying a different fuel thereto, a valve in said conduit and acting to close the conduit at all times, means for releasably holding said valve open to effect supply of the different fuel and thus determine engine operation with both said fuels, said releasable holding means including a device normally movable in a direction to release said holding means and permit valve closure, but movable in a reverse direction to effect valve opening action, and means responsive to the supply of liquid fuel for movin said device in its reverse direction to effect valve opening action.

6.- In a duel fuel engine, a first fuel supply system for the engine including a pump, a second fuel supply system for the engine including a control valve, fluid pressure means connected with said control valve for releasably holding said control valve open during normal dual fuel engine operation, a safety device connected with said releasable holding means and with said first fuel system, said device being operable in response to a predetermined decrease in the supply pressure of said first fuel system for releasing said valve holding means, and means to close said control valve immediately upon release by said device.

'7. In an internal combustion engine, a liquid fuel supply pump connected to the engine and supplied with liquid fuel at a predetermined minimum pressure, a gaseous fuel supply conduit leading to the engine, a control valve in said conduit, means constantly urging said valve into conduit closing position, fluid pressure operated motor means connected with said valve for opening the latter, a fluid pressure system for said motor means, a relay connected in said pressure system and normally operable to release the fluid pressure at said motor means for closure of said control valve, and means responsive to the maintenance of said predetermined liquid fuel supply pressure for operating said relay to permit operation of said motor means in a valve aopening direction, said last means having a connection with the liquid fuel supply whereby upon a decrease in the minimum supply pressure of liquid fuel said relay will release the fluid pressure to said motor.

LIONEL D. THOMPSON.

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

UNITED STATES PATENTS Number Name Date 1,858,824 Heidelberg May 17, 1932 2,409,611 Bodine Oct. 22, 1946 FOREIGN PATENTS Number Country Date 404,612 Germany Oct. 21, 1924

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