US2000903A - Diesel engine - Google Patents

Description

May. 14, 1935. w. LEHMANN DIESEL ENGINE Filed Feb. 20, 1934 FIG; 6

. W lu/mann- Patented May 14, 1935 UNITED STATES `DIESEL ENGINE Willy Lehmann, Eichwalde, near Berlin, Germany, assigner to Heinrich Kamper Motorenfabrik Aktiengesellschaft, Berlin-Marienfelde,

Germany Application February 20, 1934, Serial No. '712,185 In Germany March 12, 1932 4 claims. (ci. 12s-182) The present invention relates to an arrang ment and process for starting Diesel engines, more particularly lDiesel engines used for working tugs, fishing boats or the like, that is to say g engines in which strong construction and great simplicity are of importance.

The present arrangement and the present starting process make it possible to start the Diesel engines in an easy and convenient manner by hand from cold even in cold weather if desired, or by means of a small starting motor of any desired kind.

It has been found that it is impossible to change over directly the working process from the starting during which the engine works as an ordinary explosion engine, to the working as a Diesel engine.

With the hitherto known method of changing over it'is impossible to avoid immediately after the changing over, the presence of petrol in the cylinder chamber, and this results in heavy petrol explosions in the cylinder, injurious to the working, as immediately after the changing over, a high compression is produced and the engine acts as a Diesel engine.

The object of the present invention is to eliminate these drawbacks.

'Ihe complete or nearly complete elimination o! petrol from the cylinderl at the moment of the n first high compression is obtained by the followingmeans:

The connection valve between the main compression chamber and the additional compression chamber, which is open during the rst starting period, in which the engine works as an ordinary explosion engine, is closed, the admission valve proper of the engine is closed too and is not working.

The two valves mentioned remain thereupon closed for a certain period of time. The result of this is that during the suction period there is produced in the cylinder a more or less high vacuum whereupon a correspondingly smaller compression takes place `during the compression period. At the third half revolution '(in normal state this would be the combustion period), a certain vacuum is produced again at the end of the stroke whereupon, after the opening of the exhaust valve which always takes place in the normal manner, air ilows back from the silencer and is immediately expelled again. In this way a washing or scavenging of the cylinder takes place in as far as the processes described extend over one or more revolutions. The petrol disappears therefore from the cylinder.

Only now the control of the admission valvev properis released, and the engine Works as a\ Diesel engine.

In order to obtain the action described, itis -therefore necessary to make an arrangement which would ensure that a certain time will pass after the closing of the valve between the compression chamber proper and .the additional A compression chamber, before it is possible to open the admission valve and to allow its control to become effective.

The whole process together with the corresponding arrangements is particularly suitable also for medium pressure engines (in combination with a heat accumulator near the fuel nozzle) as according to the present process the engine is pre-heated so that ignition of the Diesel driving medium is produced at relatively lower degrees of compression.

In the accompanying drawing:

Fig. 1 is a vertical section through the cyl-'- inder.

Fig. 2 a plan of Figure 1. Fig. 3 a section on line A-A of Figure 2. Cylinder and admission valve during the Diesel working.

Fig. 4'the same as Figure 3, but in the starting position.

Fig. 5 is a part of Fig. 1. The change-over valve is in the starting position.

Fig. 6 is a section on line B-B of Fig. 2. Cylinder and exhaust valve.

Fig. 7 the change-over crank handle. In the drawing, a is `the chamber or space above the piston, b` the compression chamber proper, c the fuel nozzle, d the additional com`v pression chamber, e the valve drawing in the mixture, through which a mixture of petrol and air can get to d, f a sparking plug which is preferably actuated by a magneto apparatus, thek amature of which is moved jerkily in a. manner well known in itself when the. number of revolutions is low, in order to provide suicient ignition current.

a is the change-over valve which shuts ofi' the compression chamber a and b from the auxiliary compression chamber d. 'I'he valve g is applied to its seat by a spring, h is a. two-armed lever, i a shaft which is turned by hand only during the changing over from the starting to the Diesel period and is prevented from rotating both during the starting period and during the Diesel working period. In each position of this shaft it forms the axis of rotation for the lever of the exhaust valve. With the use of an eccentric however it forms also the axis of rotation of the lever of the admission valve.

k is the lever of the exhaust valve and l the exhaust valve. The control of the exhaust valve is unmodied during the starting, during the Diesel working as well as during the time provided mording to the invention between the two workm is'acam on'the shaft i which raises the valve g `on a corresponding turning o f i. n is an eccentric rigidly secured to the shaft i, which forms the pivot point of theadmission lever. o is the admission valve lever. p a crank handle operated by handwhich in the drawing is moved 1 in the anti-clockwise direction (see also Figure 7). 'I'he crank handle p is rigidly securedv to the shaft i. j q is (for instance) a handle with a correspond-- ing pin which is pressed by a spring against a ring. s the said ring which is iixed relatively to the cylinder head, r a recess in the ring s Awhich extends over a given angle, (see the following explanation), t the cam for the exhaust valve, u a heat accumulator in the chamber b which isrequired if the engine is run as a medium pressure engine. j

'I'he working of the arrangement is as fol- During the starting the crank p is in the position I. The cam m is then in the position indicated in Figure 5, it raises the valve a and re- `leasesthe connection between d, a and b.

111e engine works then as a four-stroke petrol engine, the admission valve proper (compare Fig- In this starting position, the pin of the button q engages with the groove r.

'Ihe change over to the Diesel process takes place as follows:

`After the crank has reached the position II. the lever h (compare Figure 5) springs of! from the cam m. Y

In the position III, the valve g is, completely closed (Figure 1,) but also the admission valve of the engine still remains completely closed (Figure 4) in view of a corresponding dimensioning of the eccentric n. Between the positions III and IV in Figure 7, the control of the admissiu on valve gradually begins to become opera ve.v

Without the provision of the recess r or of a corresponding other arrangement, the engine could be changed over almost instantaneously from the starting position to the working'position. This would result in explosions of the petrol still contained in the cylinder chamber.

But the pin connected to the handle q (Figure 2)is in the groove r `(Figure 7) already before the position AI is reached and if desiredeven earlier. The groove ends at an angle at which the eccentric n is still in such a. position that the lever o does not yet open the admission valve at any point. The crank p cannot be at first turned beyond this angle.

In order to make possible a further turning of the crank p, the operator who wants to start the engine working, must for instance release p, then pull out the button q so that it shall no longer engage with' the groove r, and only then 'I'his results in an intended loss of time.

In as far as the above mentioned time-wast-i ing manipulations last for instance only one second, and in as faras the engine makes in starting at the moment of changing over say 420 revolutions per minute, all the petrol traces will be Washed out of the cylinder during the time lost by seven revolutions of the engine.

If this loss of time is considered too large, the handle of the crank p and the button q could be made to coincide.. V 1

The whole starting arrangement offers particular advantages in combination with. medium pressure engine. As is well known, the latter are characterized in that their compression is always sufliciently strong to enable them to work in warm state (preferably in combination with the heat accumulator u) (Figure l) on the Diesel principle, whilst the compression is'not so great as to enable the engine to start in a re-A liable manner from cold with cold atmospheric air. The starting device such as it is here described pre-heats the engine in a manner well known in itself, and venables it to work on the Diesel principle with a weaker compression:

At the same time however' the general arrangement hereinbefore described which eliminates the petrol from the cylinder, becomes of particular importance, for the advantage of being able to build the engine lighter since it has to withstand only medium pressures would disappear if it had to be built strong enough to be able to withstand the heavy initial petrol explosions. f

I claim:

l. In a ADiesel engine, the combination of ay main compression chamber, an admission valve, an exhaust valve and actuating mechanism for said exhaust valve with an additional compression chamber in communication with the main compression chamber and having a supply inlet for admitting a starting fuel, a change-over valve for closing the communication, between the main and additional compression chambers, operating means for moving the change-over valve into and out of the closing position and actuating mechanism for the admission valve including an actuating member adjustable from an operative position to an inoperative position and adjusting means for said actuating member operatively connected to the operating means for the change-over valve for moving the said actuating member into the inoperative position o n the change-over valve being moved into the open position and into the operative position after the change-over valve has been moved into the closing position, so as to prevent the admission valve opening while the main and additional compression chambers are in communication with one another.

2,. In a Diesel engine, lthe combination 'of a main compression chamber, an admission valve, an exhaust valve and actuating mechanism for said exhaust valve with an additional compression chamber in. communication with the main compression chamber and having a supply inlet.

for admitting a. starting fuel, a change-over valve for closing the communication between the main and additional. compression chambers, operating means for moving the change-over valve into and out of the closing position and actuating mechanism for the admission valve, including an actuatingmember adjustable from an operative to an angular position in which the valve lever position to an inoperative position and adjusting means for said actuating member operatively connected to the operating means for the changeover valve formoving the said actuating member into the inoperative position on the change-over valve being moved into the open position, said adjusting means being arranged to move the actuating member into the operative position after the change-over valve has been moved into the closing position, and checking means for retarding the movement of the adjusting means beyond the closing position of the change-over valve so as to enable the engine to perform a number of idle strokes with the admission valveclosed.

3. In a Diesel engine, the Acombination of a main compression chamber, anadmission valve, an exhaust valve and actuating mechanism for said exhaust valve with an additional compression chamber in communication with the main compression chamber and having a Supply inlet tor admitting a starting fuel, a change-over valve for closing the communication between the main and additional compressionv chambers, operating means for moving the change-over valve into and out of the closing position and actuating mechanism for the admission valve, including a valve lever, an eccentric pivot for said valve lever turnable from an angular position in which the valve lever is in operative relationship with theA valve is out of operative relationship with the valve, a control shaft Vxed to said eccentric pivot and operatively connected to the .operating means for the change-over'valve so as to bring the valve lever out of operative relationship with the valve on the change-over valve being moved into the open position and into operative relationship with the valve after the change-over valve has been moved into the closing position.

4. In a Diesel engine, the combination as set forth in claim 2, in which the operating means for the change-over valve comprises an operating handle and the checking means comprise a positive stop member associated with said operating handle and a iixed stop arranged for cooperation'with the, movable stop member to arrest the movement of the operating handle when the change-over valve is in the closing positicm, said movable stop member being movable from a posit-ion in which it can engage the xed lstop into a position in which it is incapable of such engagement, whereby the further movement o! the operating handle beyond that corresponding to the closing position of the change-over valve is delayed until the movable stop member is moved into the second-mentioned position.

WILLY LEHIVIANN.

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