US2003478A - Overspeed device - Google Patents

Description

C. M. BOVARD ovERsPEED DEVICE June 4, 1935.

Filed Aug. l2,y 1931 2 Sheets-Sheet l BY ML?? ATTO R N EVS June 4, l935 c. M. BovARD 2,003,478

OVERSPEED DEVICE Filed Aug. 12, 1951 2 sheets-sheet 2 INVENTOR wow-d, Ow. l 71ML() ATTOR EYS Patented June 4, 1935 OVERSPEED DEVICE Charles M. Bovard. Grove City, Pa., assignor to Cooper-Bessemer Corporation, Mount Vernon, Ohio, a corporation of Ohio Application August 12,

4 Claims.

The invention relates to internal combustion engines of the type wherein fuel under pressure is injected into the engine cylinders, and has for a general object to supplement the usual regu- 5 lating system of the engine by providing a safety device which operates upon the occurrence of abnormally high engine speed, to reduce the pressure on the fuel line to a low value, thereby safeguarding the engine against injury in case the ordinary fuel regulating system should fail to operate properly.

Diesel engines, for example, Aare in common use wherein fuel oil under pressure is supplied from a common manifold to the various cylinders through branch connections in which are located mechanically actuated valves which are controlled by a speed governor, to admit quantities of fuel regulated according to the speed of the engine. And in applying the present invention 20 to Diesel engines, a safety device is employed which under abnormally high speed conditions automatically reduces the fuel pressure in the manifold to a low point, preventing further overspeeding; however, a fairly low pressure is preferably maintained in the manifold under such conditions, to prevent the fuel system from becoming air bound. It should be understood that the principles vof the invention are applicable to other internal combustion engines wherein liquid or gaseous fuels are supplied under pressure.

Further objects and advantages of the invention will be in part obvious and in part specifically referred to in the description hereinafter contained which, taken in conjunction with the accompanying drawings discloses a preferred embodiment of the invention. Such embodiment, however, is to be considered as merely illustrative of the principles of the invention. In the draw ings'- Fig. 1 is a view partly in section and more or less diagrammatic of an overspeed device adapted to operate in accordance with the invention.

Fig. 2 is a sectional view showingsuch device in relationto a typical engine assembly'.

The invention is disclosed as applied to a Diesel engine of the type above referred to wherein oil is maintained under injection pressure in a manifold I8 from which branch pipes I6 lead to the various cylinders; suitable means is provided regulating the amounts of fuel supplied to the cylinders under different operating conditions. In applying the present invention to an engine of the above type, anl overspeed device is employed having an overspeed valve connected to the manifold I8, which remains closed or inactive under into the fuel line.

1931, serial No. 556,471

normal operatingconditions, but which is actuated under abnormally high engine speeds, to relieve the pressure within the manifold I8.

As shown in Fig. 1, for example, this overspeed valve includes acasing 36 in which operates a sliding valve 31 having a reduced portion 38 which connects the ports 39 and 40 when valve 31 is raised. The port 38 is connected by a pipe coupling 4I and pipe 42 to the fuel manifold I8 .and the port 40 is connected by a, pipe 45 to the source of fuel, and hence when valve 31 I is raised as above described, the fuel pressure .in manifold I8 may be relieved. The port 40, however, is'normally closed by a relief valve 43 which also closes a port 44 communicating with the pipe 45 as above mentioned. A spring 46 may be adjusted bythe threaded plug 41 to control'the pressure at which therelief valve operates. As shown, a cap 48 is threaded on. .the ex- ,.terior of the plug 41.

'Ihe position of the valve member 31 is controlled according 'to the speed of the engine by any suitable type of speed governor, such as responsive mechanism indicated diagrammatiycally at 60 in Fig. 1. It will be understood that this valve may be operated from the speed governor such as commonly employed in engines of the above type, although I prefer to employ a separate governor for this purpose, to insure the relief of pressure on the fuel line in ease the usual governor should beout of order. l

'Ihe valve 31 is moved by the governor 60 in such manner as to connect the ports 3!) and 4I) upon the occurrence of a predetermined abnormally high engine speed and under these conditions the fuel pressure in manifold I8 will be high enough to unseat the relief valve 43, thus relieving the pressure in manifold I8 down to a point at which spring 46 moves the valve 43 to closed position. In applying the invention to Diesel engines, the spring 46 is preferably set to return Valve 43 to closed position at a fuel pressure somewhat above or at least equal to atmospheric pressure, to prevent air from getting In fact the pressure drop in manifold I8 caused by the operation of the overspeed device, need not be so great as to stop the engine entirely, but merely suilcient to prevent continued operation at unduly high speed.

In Fig. 2 the overspeed device above described is shown in relation to a Diesel engine assembly which should be regarded as merely typical and it Will be understood that the invention is not limited in its application to engines of this par- Cil which uid under pressureis supplied by a pump I9, which draws fuel from a fuel supply tank 20 and delivers it under pressure through a pipe 2l to the common manifold I8. The pump I8 is operated from the crank shaft b y means of a sprocket chain 22 driven by a sprocket wheel 23 connected to a gear wheel 24 meshing with a gear wheel 25 on the crank shaft I4. The

sprocket chain, as indicated passes over a sprocket wheel 26 which by suitable drivingv connections, as indicated, operates the pump I9. The sprocket chain'22 also passes over asprocket wheel 2l secured on the cam shaft 28 which carries cams 2S operating on rollers on reciprocating plungers 30 which operate bell cranks 3I connected to the needle 32 of the injection valve I5.

A wedge 33 controlled by the governor 3l and lying between the plunger 30 and the bell crank 3| controls the amount of fuel injected. The construction is such that as the load on the engine increases and its speed decreases, the wider portion of the wedge 33 is moved in between the plunger and the bell crank to cause the valve to be lifted highervto increase the amount of fuel oil delivered at each injection, and as the speed increases the wedge is withdrawn to reduce the amount of fuel oil delivered at each injection, thus limiting the speed of the engine when not under load.

The governor 60 shown diagrammatically inl Fig. 1 may be regarded as contained within the housing 35 of Fig. 2, and driven in any suitable manner, as by sprocket 65 (Fig. 2) meshing with chain 22. The overspeed valve casing 36 is shown mounted upon the housing 35', with the pipe I2 connected to the pipe 4I which leads to the manifold I8, and the pipe connected to the fuel supplyvtank 20.

As shown in Fig. 2 the valve casing 38 may also be provided .with a passageway 16 communicating with port M and leading to the space around the bottom of valve. stem 31, so that any fuel which leaks past the valves may be carried pipe 11 indicated at the botspirit of this invention, are comprehended withinv the terms of the appended claims.

I claim:

1. 'Ihe combination with an engine of the class described of a fuel line adapted to supply fuel under pressure to the engine cylinders, speed controlled means for regulating the amounts of fuel so supplied, a separate speed responsive mechanism, and means actuated by said speed responsive mechanism under `abnormally high speed conditions for relieving the pressure in said fuel line, said last mentioned means including a valve acting to limit the degree of such pressure relief.

2. The combination with an engine of the class described, means for delivering fuel under pressure to theengine cylinders, means for regulating the amounts of fuel so supplied, a relief valve adapted to be operated by the fuel under pressure for reducing the pressure of the fuel, and means automatically operable as the engine attains a predetermined speed for establishing com- -rnunication between the fuel under pressure and the relief valve to operate the relief valve.

3. The combination with an engine of the class described, of a fuel line adapted to supply fuel under pressure to the engine cylinders, means for regulating the amounts of fuel so supplied, and means responsive to speed conditions for relieving the pressure in said fuel line below the normal pressure under abnormally high speed conditions and for 'restoring normal pressure under normal speed conditions.

4. In combination with an engine of the class described, of a fuel manifold connected to the engine cylinders to supply fuel thereto, means for supplying fuel under pressure to said manifold, means for regulating the amounts of fuel so supplied to the cylinders, a valveA connected between said manifold and a point at lower pressure, and means responsive to speed conditions for opening and closing said valve respectively to relieve the pressure in said manifold under abnormally high speed conditions and to restore normal pressurev under normal speed conditions.

i -CHARLES' M. BOVARD.

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