US961077A - Means for facilitating the starting of internal-combustion engines. - Google Patents

Description

P. PURDY. MEANS FOR PAGILITATING THE STARTING OF INTERNAL COMBUSTION ENGINES.

APPLICATION FILED UB0. 23, 190B.

Patented June 7, 1910.

f2 vezzzvrx P. PURDY. v MEANS FOR FACILITATING THE STARTING 0I INTERNAL COMBUSTION ENGINES.

APPLICATION FILED DBO. 23, 1908.

' Patented June 7,1910;

'2 SHEETS-SHEET 2i iinrrnn srairasra rnnr OFFICE.

FREDERICK PURDY, or KENOSHA, Wisconsin, ASSIGNOR 4T0 THOMAS aJErrEaY, or

x'anosna, WISCONSIN; KATE E. JEEEEEY, CHARLES E. JEFFERY, AND HAROLD w. JEFFERY ExEcoToRs OESAID THQMAS i2.- JErrEEY. DECEASED.

MEANS FOR FACILITATINGLTHE STARTING F INTERNAL-COMBUSTION ENGINES.

Specification of Letters" Patent. Patented u *j 1 910.

Application filed December 23, 1998. Serial No. 488,888.

To all whom it may concern:

Beit known that-'I, FREDERioK PURDY, a

citizen of the United States, residing atgines, and declare the following to be a full,

clear, and exact description of the same, such as will enable others-skilled in the art to which it pertains to make and use the same,

reference being had to the accompanying drawings, which form apart of this specification. I

One of the disagreeable features of nal combustion engines is the necessity for means certain, it being at turning the crank shaft manually, that is, cranking, in order to start them. Multicylinder engines are sometimes enabled to start under their own power upon the COIIlpletion of the firing circuit. Even in the bestforms of multi-cylinder engines this starting on spark, as it is called, is by no times absolutely impossible to starttheni in this manner so that resortinust very oftenjbe had to the process of cranking. It has generally been believed-that the main factors in giving an engine capacity to start on spark are the perfection of compression and the absence of unnecessary friction; but engines n which these two conditions are as nearly perfect as it is possible to have tliem do not always start on spark and, in fact, some of them never do. i

When an engine is stopped in the usual way the firing circuit is, of course, interrupted before an explosion can take place in the cylinder wherein the piston is just ready has begun its power stroke. In the ordinary four-cylinder engine, when one piston is on the power stroke, another is onthe compression stroke,

,haust stroke and the remaining piston is on the intake stroke. Consequently whensuch an engine stops with the charge behind the piston which is on its working stroke unexloded there will be two cylinders containmg charges undercompression and two cylinders in which there is no appreciable ,pressure.' If then, there is no loss of compression, the engine should finally cometorest with all of the pistons midway of their strokes, since this is the position-of, eqiii inter a third ison the eX-.

librium between the two pistons which are under pressure. This osition of the pistons 'is also the most eective one since the leverage between the piston on the working stroke andthe crank shaft is at a maximum. I have found whenever an enginezhas been able to "start under its own po wei the con- .dition .of equilibrium in whichthe engine -was' placed was-such that the pistons were approximately midway between theends of their strokes; and v where an engine was unable to start under its own power or couldonly start with difiiculty, the piston on its working stroke had come to rest nearer .the beginning of the working'fstroke than theend'thereo'f. This latter condition can, of course,-only arise because of a loss of compression -in the cylinder wherein the piston is on the" workingv stroke without a corresponding lossof pressure in the cyli1ider wherein the piston is'on the compression stroke, Nqwin most engines of this class it has been found that the most satisfactory results are producedby opening the exhaust valves before the ends of the working strokes are reached, the cranks connected to the pistons on their working strokes being usually in positions ranging from 30 degrees 'to'5O -degrees away from the position which they occupywhen the pistons are at the ends of their working strokes. When, therefore, the engine is stopped, the two opposing elastic cushions working against the pistons which are respectively on their worki ijg and compression strokes tend to bring the engine to a conditionof rest with the pistons in midway positions: However, thei'e-tvillbe more or lessv oscillation from one side; to the other of this natural position of equilibrium and, if the engine is free from friction and the compression space is comparat vely large or the fly wheel is quite heavy the OSClllatlOll may be so great as to open the s ub aiist valve associated with the cylinder wl'ifetein the piston is 'on its working stroke; therpby allowingsome of the charge to escape and 1Cll1C-- ing the pressure. As a result the condition of equilibrium willb'e found not when the pistons are midway when the piston which is on its working stroke has returned more or less toward the .be inningof its working stroke. It will be of their strokes but' seenthat if the reduction of pressure in the power cylinder is considerable the volume of gas remainin in. the power cylinder will not produce su 'cient pressure to overcome the angular disadvantage and the increased resistance in the compression cylinder so that, although the charge in the power cylinder may be ignited, it will not start the cycle of operation.

The object of my invention is to prevent the dissipation of the pressure in the power cylinder of a multi-cylinder engine when the engine is stopped so as to permit the engine to start under its own power when the charge in the power cylinder is subsequently ignited.

The various features of novelty .whereby -my invention is characterized will hereinafter be pointed out with particularity in the claims; but for a full understanding of my invention and of its object and advantages reference may be had to the following detailed description. taken in connection with the accompanying drawings, wherein:

Figure 1 is a front elevation of a multicylinder internal combustion engine showing one embodiment of my invention incorporated therein; and Fig. 2 is a section taken through one of the cylinders.

It is, of course, evident that various m'echand E respectively.

F is an exhaust conduit common to all of the cylinders; bc-d" and e are spark plugs for igniting charges; G is a portion of the energizing circuit for the igniters.

By referring to Fig. 2 it will be seen that when the piston H is approaching the end of the power stroke and the crank I con-. nected therewith is still a considerable dis tance from its lower center, the exhaust;

valve K is just being opened through the cam L. Assuming that the engine has been sto ped by interrupting the igniting circuit be ore the charge above the piston H has been exploded: If the piston oscillates within sufliciently wide limits to reach the position indicated, the valve K will be opened. The relation of the inlet valve and 7 its actuating cam on the compression cylinder is, of course, such that this valve will not be affected by the oscillation of the engine'when seeking its position of equilibrium. Consequently some of the pressure in the power 0 llnder would ordinarily be dissipated whi e that in the compression cylinder remained undirninished. When the engine finally came to rest the piston H would not be at the middle of its stroke but would be up near the top of the cylinder, thedistance from the center, of course, depending upon the extent to which the pressure on the power cylinder has been impaired. I If only a little of the pressure in the power cylinder was lost the position of equilibrium would be such that the engine would still start under its own power. A considerable loss of pressure would, however, make it impossible to start the engine without cranking. The loss of pressure in the power cylinder to a point where the engine will not start under its own power may be avoided by the simple expedient of placing in the exhaust conduit a valve M which is closed when the engine is stopped. If, thereafter, during the oscillation of the engine, the exhaust valve on the power cylinder is opened, the charge in the power cylinder will enter the exhaust conduit until an equalization between the pressure'in the conduit and that in the cylinder is effected; As soon as the engine ceases oscillating the exhaust valve will, of course, be closed and if the engine is properly designed the'pressure in the power cylinder will thereafter be maintained for a com aratively long time. When it is desire' to start the engine it is only necessary to open the valve M so as to permit the engine to exhaust in a normal manner when it begins to operate. This auxiliary valve may take any desired form, the one which I have 00 found: to work quite satisfactorily being in the form of a disk pivoted as at m within the exhaust conduit and arranged so as to make an acute angle with the axis of the conduit when closed. Such a valve may m5 readily be ground-to make a tight closure for the conduit. The valve may be operated in any suitable manner as, for example, by means of a lever N-and rod '0.

In order that the breaking of the firing circuit with theclosing of the valve may be insured there may be a switch in the firing circuit controlled by the valve sothat whenever the valve is closed the firing circuit will be interrupted. In the drawings I have shown such a switch consisting of two stationary contact pieces P and P and a bridge contact P carried by the operating lever for sire to cover all other embodiments thereof 1130 as will be evident from the terms employed in the definitions of my invention constituting theappended claims.

Having now described my invention, what.

I claim as new and desire to obtain by Letters Patent is:

1. In an internal combustion engine, aplu rality of enginecylinders, pistons in said cylinders, means for normally exhausting pressure from' said cylinders at predetermined points between the ends of the working strokes of said pistons, andmeans for maintaining the cylinders closed against atmosphere when the pistons reach said predetermined points upon stopping the engine so ,as to maintainpressure in the cylinders.

2 In an internal combustion engine, a plurahty of engine cylinders, pistons in said cylinders, means'for normally exhausting pressure from said cylinders at predetermined 'points' between the ends of the working mined points during the working strokes of n said pistons and valve mechanism in addition to the exhaust valves for closing said conduits upon stopping the engine.

4. In an internal combustion engine,.a plurality of engine cylinders, pistons in said cyl- 'inders, an exhaust pipe connected to the exhaust ports of said cylinders, exhaust valves,

. means for opening said exhaust valves at predetermined points during the 'working strokes of said pistons, and a tightly seating valve in said pipe adapted to be closed upon stopping the engine.

5. In an internal combustion engine,'a plurality of engine cylinders, pistons in said cylinders, a firing circuit, means for normally exhausting pressure from said cylinders at predetermined points between the ends of the .working strokes of said pistons, and means for preventing the exhausting of pressure at said predetermined points and at the same time rendering said firing circuit 'inoperative.

6. In an internal combustion engine, a plurality of cylinders, pistons in said cylinders, exhaust conduits from said cylinders, exhaust valves in said conduits, means for actuating said valves to exhaust pressure from said cylinders at predetermined points between the ends of the working strokes of said pistons, valve mechanism for closing said conduits, a firing circuit, and means associated with said valve mechanism for rendering said circuit inoperative when the valve mechanism tion.

In testimony whereof, I sign this specification in the presence of two witnesses.

FREDERICK PURDY. Witnesses:

J. P. ZENS, L. J. HAMMOND.

is in conduit-closing posi-

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