US2190345A - Starting device for high compression engines - Google Patents

Description

Feb. 13, 1940.

R. D. ACTON 2,190,345

STARTING DEVICE FOR HIGH COMPRESSION ENGINES Filed July 31, 1935 3 Sheets-Sheet 1 90 1.9142 1 45 J5 20 j 1 J7 o 0 J02 v 7 4 7 J05 -46 gfi Feb. 13, 1940. R. D. 'ACTON I STARTING DEVICE FOR HIGH COMPRESSION ENGINES Filed July 31, 1935 3 Sheets-Sheet 2 Feb, 13, 1940. A T N 2,190,345

STARTING DEVICE FOR HIGH COMPRESSION ENGINES Filed July 31, 1935 '3 Sheets-Sheet 3 Patented Feb. 13, 1940 PATENT OFFICE STARTING DEVICE FOR HIGH ooM- PRESSION ENGINES Russel D. Acton, Chicago, Ill., assignor to International Harvester Company, a corporation of New- Jersey Application July 31,

i Claims.

This invention relates to internal combustion engines. More specifically it relates to a starting system for compression ignition engines.

In the operation of compression ignition engines using a liquid fuel of low volatility the compression must be high particularly to secure ignition when starting a cold engine. With an engine of a size suitable for tractors and for uses requiring an equivalent power plant the eifort required to rotate the engine crankshaft on compression is such that manual cranking is either impossible or impracticable. With air injection engines, such as widely used for marine engines, the engine-may be started by driving it with com- 16 pressed air until a speed is attained sufiicient to carry through and start the engine on compres sion ignition.

Constructions have been devised utilizing a starting system in which a compression ignition engine is provided with means for initially lowering the compression ratio and operating with a volatile fuel mixture supplied by a carburetor and with spark ignition. The engine may then be manually cranked and operated on the Otto cycle until the shift is made to'the Diesel cycle with compression ignition. The Wentworth Patent 1,225,295, discloses a starting system of this type in which the change over to Diesel operation is made by manually shifting the various controls. The Johnston Patent No. 2,032,755, dated March 3, 1936, which is assigned to the same assignee as this application, shows in an engine of the type in which the present invention is embodied a starting-system incorporating a shifting mechanism-T operable by rotation of the engine to shift from Otto to Diesel cycle after a predetermined number of revolutions of the engine, the number being manually preselected by the operator. The system has proved satisfactory, but is unsatisfactory in the respect that the time of shift remains to be determined by the operator and may not correspond in any way to the theoretically correct time.

The'object of the present invention is to provide a starting system for compression ignition engines incorporating means actuated by means responsive to a condition of engine operation to shift from low compression with spark ignition to high compression with compression ignition when the engine has attained a condition indicative of its ability to ignite and operate on compression ignition. More specifically the invention relates to the provision of a shifting means automatically operable to shift from Otto to Diesel cycle when the speed and/or the tempera- 1935, Serial No. 33,952

ture of the engine indicate that the engine will ignite by compression and operate on the Diesel cycle,

Another object is to locate a temperature responsive device at a point in the engine adjacent the combustion chamber, which is indicative of the ability of the engine to ignite injected fuel by the heat developed by compression.

Another object is to incorporate a shifting means for changing from Otto to Diesel cycle by 10 means of a governor for a fuel injection pump.

Other objects and the means by which they are attained will be apparent from the detailed description which follows and the drawings, in which:

Figure l is a side elevation showing the upper portion of an engine incorporating the starting system of this invention;

Figure 2 is a cross section taken substantially on the line 2-2 of Figure 4 of the injection pump 20 showing the operating means for the speed responsive shifting means;

Figure 3 is an elevation showing a modified form of shifting means actuated by the heat sensitive device alone;

Figure 4 is an elevation of the fuel injection pump broken away on a vertical section, as shown by the section line 4-4 in Figure 2, to'show the governor control incorporated in the pump;

Figure 5 is a sectional view transverse to the block of an engine which is provided with an auxiliary combustion chamber and means for operating on Otto or Diesel cycle.

Figure 6 is a detail of the linkage between the carburetor and the shifting mechanism; and,

Figure 7 is an elevation partially broken away in section to show the valve for switching from a carbureted mixture to air.

A portion of an engine is shown in Figure 1 including the upper portion of a block 80, cylinder 40 head II, and a valve cover I2, the engine shown being of the overhead valve type. A shaft I3 is shown arranged transversely and projecting laterally of the cylinder head II, this being the shifting shaft, as will be hereinafter described. A member l4 rigidly mounted on the shaft l3 includes a handle I5 for setting the shifting shaft against the action of a tension spring l6 secured to the handle and to a bracket I! mounted on the cylinder head. The member I 4' also carries a cam portion l8 terminating in a latch l9 adapted to engage a notch formed in a lever 20 pivotally mounted on the bracket IT. The connections of the shifting control devices with the 55 lever 20 will be described later in connection with the detailed description of these devices.

In so far as the shifting shaft l3 and its latch means are concerned this disclosure is substantially the same as that disclosed in the Johnston patent, previously referred to, in which the different elements utilized for operating the engine are shown more fully.

In the cross section of the cylinder head shown in Figure 5, the shifting shaft 3 can be seen in the background behind the other elements and portions of the head shown in section. A worm gear 2| on the shaft i3 engages a worm wheel 22 on a shaft 23 extending in the direction longitudinally of the engine, it being understood that this engine illustrated has a plurality of cylinders, the construction of each of which is exactly the same as the one shown in cross section.

The shaft 23 carries cams 24, each of which engages a rocker member 25 for each cylinder. One end of the rocker member is seated on a washer supported by a spring 25 mounted in a pocket formed in the cylinder head. The other end of the rocker member engages the upper surface of a member 21 screw-threaded on to the stem of a valve 28. Said valve controls communication between the main combustion chamber 29 of the engine and an auxiliary combustion chamber 30 utilized for lowering the compression of the engine for starting. The spring 3| maintains the valve 28 in seated position except when opened by action of the rocker member 25 when it is depressed by the cam 24. A spark plug 32 is mounted in the auxiliary combustion chamber 30 for ignition when the engine is operated on the Otto cycle. The overhead valve arrangement is shown, but will not be described in detail, as it is conventional and forms no part of the present invention.

A partial cross section and partial elevation of the air inlet and carbureting means is shown at the lower right hand Figure 5. A side elevation is shown partially in section'in Figure '7. A control shaft 33 is connected by a lever 34 at its end and a link 35 with a lever 35 mounted on the shifting shaft l3, as best shown in Figure 6. A simple carburetor 33' is diagrammatically illustrated, to which fuel is supplied by a conduit 31. The shaft 33 carries a valve 34' operable to supply air only to the air inlet conduit 38 or to'supply a volatile mixture from the carburetor 33. This construction is shown more completely in the patent above referred to. In

so far as this disclosure necessitates the showing of the elements making up an engine, it is believed that the parts shown satisfactorily illustrate the essential elements to define the novel starting system.

In Figure 5 a precombustion chamber 39 is illustrated. Fuel is supplied to this precombustion chamber as is conventional in the Diesel engine art through a conduit 39' and a nozzle 40' mounted in a supporting block 4| fitted in the upper end of y the precombustion chamber. These members are shown only diagrammatically, as any conventional construction may be used. The precombustion products are discharged through the opening 40 into the main combustion chamber 29. There are certain specific locations in an engine cylinder adjacent the combustion chamber which are more indicative of the enpansible fluid is located in a pocket 42 formed in the cylinder head. To rapidly transfer heat adjacent the opening 40 to the heat responsive unit, copper pins 43 are inserted in the head extending closely adjacent the interior of. the combustion space. It is to be understood that the thermosensitive element may be located in any position where heat from the desired location in the combustion space may be readily transmitted.

A shaft 44 rigidly connected .to the heat responsive device 4| extends through the insulated cover 45 and is pivotally connected to an operating lever 45. Saidlever is pivoted intermediate its ends on a bracket 41 integral with the cylinder head. At its upper end the lever 46 is provided with a latch or hook 48, which is positioned to engage the upper edge of the latch lever 20 when it is engaged with the shifting shaft with the shaft in its low compression position.

At this point the operation of the expansible bellows can'be best described. When the temperature in the combustion space around the opening 40 reaches a point at which the heat responsive device 4| is designed'to operate, the

50 with the bracket I1. In the modification of 1 Figure 3 the spring 50 acts to raise the latch lever 20 when the hook 48 is released, whereupn the spring lfi'operates the shifting shaft to cut off the auxiliary compression chamber and to operate the other controls for shifting from Otto to Diesel operation.

As illustrated, the engine is provided with a fuel pump housed in a casing 5| secured at one side of the engine block I'll. Said casing includes pump mechanism and a governing device therefor, as will be described. Said governing device also operates the shifting mechanism contained in the pump casing. A pump shaft 52 adapted to be driven from the engine crank shaft in timed relation with respect thereto by means of a flanged coupling 53 extends longitudinally of the pump casing 5|. Said shaft carries a plurality of cams 54, each cam being positionedto operate a fuel injection piston 55 through a suitable force transmitting linkage. Said linkage consists of a lever arm 56 rotatably mounted on a shaft 55'. A roller 51 carried by the lever arm 56 contacts with the cam on the shaft 52, motion being transmitted through the lever arm to a tappet 58- which operates the pump piston 55. As is conventional in pumps of this nature, a variable stroke is provided for by varying the time of opening of a by-pass valve 59, as shown in Figweights 64. Said weights are provided with radially and inwardly extending portions 65, through which pins 66 extend. The pins pivotally support blocks 61 which are positioned in an annular channel formed between spaced radial extensions 68 of a sleeve 69. The sleeve 69 is slidably mounted on an extension of the shaft 52. Pressure exerted by the governor weights on the sleeve 69 is transmitted through a ball bearing assembly 18 to a cylindrical member H, which is formed with a radially extending flange at one end for abutting the ball bearing assembly. A compression spring 12 mounted in the member 1| abuts a flanged collar 13 in contact with the inwardly extending flange on the member 1I. Said spring at its other end abuts a stop 14, only a portion of which is illustrated. The spring acts to counterbalance the governor weight action.

The cylindrical member H is provided with spaced flanges 15, between which pins or other suitable means carried by a bell-crank member 16 are engaged. Movement of the cylindrical member transmits angular movement to the bellcrank member 16 which is pivoted on a pin 11 carried by the casing and mounted at right angles to the axis of the shaft 52.

The bell crank member 16 is formed with an extension arm 18 provided with gear teeth positioned to engage the bevel gear 19 mounted on the governorshaft 62. It will be understood by this construction that movement of the governor weights oscillates the shaft 62, thereby changing the angular position of the eccentric 6| to regulate the stroke of the injection pistons.

By means of a worm wheel 88 on the pump shaft 52 and a gear 8| on a vertical shaft 82 mounted in the casing I8, continuous angular movement is transmitted to saidshaft. By means of a worm 83 on the shaft, as shown in Figure 2, continuous rotation is also transmitted through a worm wheel 84 to a shaft 85 mounted in the casing at right angles to the shaft 83 and in a substantially horizontal position. The shaft 85 carries a cam 86 which engages the face of a tappet member 81 slidably mounted in a portion of the casing I8. A pressure spring 88 abutting a flange on the tappet member 81 returns the tappet from raised position and maintains it in contact with the cam 86.

A member 89 in the form of a rod vertically positioned alongside the engine block provides means for actuating the trip of the shifting mechanism. Said rod passes through the latch lever 28 and is slidable with respect thereto, a nut 98 being threaded on the upper end of the rod above the latch member. Said nut provides for adjustment and has a means for providing for lifting the rod 88 when the cam I8 engages the latch lever and lifts it vertically.

The shift rod 88 is slidably mounted with respect to the casing and extends thereinto in alignment with the tappet 81. Means are provided for preventing angular movement of the rod '89 during reciprocation thereof illustrated as a key 9I. The rod 89 terminates a substantial distance above the tappet 81, being provided with a pivoted extension lever 92, which is adapted under predetermined speed conditions of the engine to engage the tappet 81 for operating the shifting mechanism.

A transverse shaft 93, slidably mounted in a portion of the casing, is provided with a contact head 94 adapted to engage a cam 95 rigidly car-v ried by the governor shaft 62. Said cam is mounted in an angular position with respect to the governor shaft so as to engage the transverse shaft 93 and move it in the direction of the lever 92 when the speed of the engine has attained a predetermined rate at which the en- 'gine is capable of operating on high compression with compression ignition.

A hollow tappet member 96 is slidably mounted on an end portion of the shaft 93 of reduced diameter. A compression spring 91 abuts the extended head of the member 91 and an abutting washer 98 mounted on the reduced end portion of the shaft 93. The head portion of the member 96 engages a rounded extension 99 on the lever 92. A spring I89 is wrapped around the pivot pin connecting the lever 92 with the rod 89 and the ends of the spring are hooked over said elements to normally hold the member 92 in the position shown. In this position the tappct 81 does not engage the lever 92 to lift the rod 89.

The details of the pump and the injection system have not been shown or described. Injection lines I 8| are shown connecting the in-- jection pump with the top of the cylinder block at which points the injection lines connect with injection nozzles fitted in the precombustion chamber 39.

The operation of the mechanism for controlling shifting by heat alone has been described in connection with the description of the modification shown in Figure 3. As shown in Figure 3, the temperature actuated control acts in conjunction with the speed actuated controlling means. When the engine has reached a speed for which the mechanism is designed and adjusted to trip the shift from Otto cycle to Diesel cycle, the cam 95 has been rotated to move the shaft 93 a sufficient distance to engage the lever 92 with the head of the tappet 81. As this tappet is continuously reciprocating at a slow rate, it is possible that the engine speed at which lateral movement of the shaft 93 takes place may move the lever 92 when the tappet member 81 is in lifted position. It is to provide) for this condition that the resilient construction is provided by the member 96 and the compression spring 91. ,This spring is compressed if the tappet member 81 is in raised position However, as soon as it drops, being returned by the spring 88, the lever 92 is moved over into a position substantially parallel with the rod 89. Upon the next stroke of the tappet member 81 the rod 89 is lifted vertically, thereby exerting pressure on the latch lever 28. If the temperature of the engine is such at the point in contact with the heat responsive device 4| that the latch 48 has been moved out of restraining position, as shown in dotted lines in Figure 5, the lever 28 is immediately tripped. As soon as the shaft I4 is released it is rotated by the spring I6 to shift the controlling mechanisms,

as previously described; for operation on the Otto cycle to operation onthe Diesel cycle, the most important feature of this shift being the change in pressure. The mechanism for effecting this change is shown completely and described in detail. The other mechanisms are clearly shown in the Johnston patent previously referred to.

Under certain conditions of operation the temperature may not have reached the predetermined condition for which the latch 48 is constructed to disengage. To take care of this condition a stop member I 82 is mounted on the rod 89 below the latch member 28. A compression spring I83 abuts the stop member I82 and the lower side of the latch lever 28. Until the latch 48 is disengaged the member 89 is merely reciprocated against the compression spring I03. As soon as the latch 48 is disengaged the shifting shaft is tripped. Under some conditions the heat control may not be utilized, the shifting of a means for providing shifting which is dependent upon the speed of the engine. It has been incorporated with the pump governor to reduce the mechanism required and to utilize an existing mechanism for an additional function. During actuation of the device the load on the governor would be sufiicient to disturb proper sensitive governing action. However, as soon as the latch member 20 has been tripped, the cam I 8 lifts said member and the rod 89 carried thereby to such a height that it no longer engages the tappet 81. The pressure of the spring I00 is sufficiently small as to not apply pressure to the cam sufficient to put a prohibitive load on the governor.

In the operation of a Diesel engine utilizing low compression for starting, it is very desirable that means be employed to prevent excess running on 'low compression. For example, the valve controlling communication between the auxiliary compression chamber 30 and the main combustion chamber 29 is easily burned by the rapid flow of burning gases through the communicating area. There are other reasons for shifting as soon as operation on the Diesel cycle is satisfactory. However, an attempt to shift before the engine conditions are proper for turning the engine over on high compression and for igniting the injected fuel results in failure to continue operation, and also results in excess oil dilution due to failure of the injected fuel in igniting and burning. This invention as above described contemplates a method and a mechanism for carrying out the method in which the shift from Otto to Diesel operation is accomplished at a theoretically correct time either by the temperature condition in the engine, by the speed of rotation of the engine, or by a combination of these two conditions. By this method and mechanism the operator is. not dependent upon, as in previous constructions, shifting at the proper time.

It is to be understood that applicant has shown and described only certain forms of devices for shifting from Otto to Diesel operation upon the attainment of certain predetermined conditions resulting from engine operation and that he claims as his invention all modifications falling within the scope of the appended claims.

What is claimed is:

1. In an internal combustion engine formed with a combustion chamber, the combination of means for operating the engine on a volatile mixture with spark ignition and on low compression, means for operating the engine on high compression with a non-volatile fuel and com- 7 pression ignition, means operable by rotation of the engine for shifting from one operatingmeans to the other, heat responsive means mounted in heat exchange relation with a portion of the engine combustion chamber at a location indicative' of the engine's ability to ignite and operate on compression ignition, and means operated by said heat responsive means for effecting the actuation of the shifting means.

2. In an internal combustion engine, the combination of means for operating the engine on a volatile mixture with spark ignition and on low compression, means for operating the engine on high compression with a non-volatile fuel and compression ignition, means for shifting from one operating means to the other, actuating means operatively associated with the shifting means rendered effective by a condition of engine operation indicative of the engines ability to rotate on high compression, and means operatively associated with the shifting means rendered effective by another condition of engine operation indicative of the ability of the engine to ignite with compression ignition effective to control the time of shifting to high compression.

3. In an internal combustion engine formed with a combustion chamber, the combination of means for operating the engine on a volatile mixture with spark ignition and on low compression, means for operating the engine on high compression with a non-volatile fuel and compression ignition, means for shifting from one operating means to the other, speed responsive means operated by the engine, means connecting said means .to the shifting means operable to shift from low compression to high compression when the engine has attained a predetermined speed sufficient to ignite and operate on compression ignition, and heat responsive means in heat exchange relation with the engine operable to retard the shifting to high compression by the speed responsive operated means until the engine temperature is sufiicient for operation on compression ignition.

4. In an internal combustion engine formed with a combustion chamber, the combination of means for operating the engine on a volatile mixture with spark ignition and on low compression, means for operating the engine on high compression with a non-volatile fuel and compression ignition, means operable by rotation of the engine for shifting from oneoperating means to the other, heat responsive means mounted in heat exchange relation with a portion of the engine heated during initial operation and at a location indicative of the engine's ability to ignite and operate on compression ignition, and means'operated by said heat responsive means for effecting the actuation of the shifting means.

RUSSEL D. ACTON.

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