US2236634A - Method and means for starting diesel engines - Google Patents

Description

= P 1941. o. YAMASHITA 2.236.634

METHOD AND MEANS FOR STARTING DIESEL ENGINES Pil ed June 6, 1939 s sweats-Sheet 1 A ril 1, 1941. o. YAMASHITA IETHOD AND "EARS FOR STARTING DIESEL ENGINES v Filed June 6, 19:9 3 Sheets-Sheet z April 1, 1941- o. YAMASHITA 2.236.63

usmon AND laws FOR smmue mam. mamas Filed June 6, 1939 3 Sheets-Sheet 3 v .Z'nvenz a dyamashit Patented Apr. 1, 1941 UNITED STATES. PATENT OFFICE METHOD AND'MEAN S FOB STARTING DIESEL ENGINES Okiye Yamas'hita, Tokyo, Japan Application June 6, 1939, Serial No. 277,714

comm.

My invention relates to a method of startin four-cycle multi-cylinder Diesel engines and more particularly to a Diesel engine 01 abnormally low compression ratio having special change-over valve gear for starting the engine by this method, and its objectis' to easily start such engines with comparatively low compression ratio. developing higher power by supercharging'.

It is well known in the art that if the suction air for Diesel engines is increased by supercharging the output of the engine can be increased, but. the explosion pressure might be raised excesively high. Accordingly if in a Diesel engine designed for ordinary compression ratio, that is, 14 to 18 the compression ratio might be reduced below 14, e..g. 8 to 12, the maximum explosion pressure can be sufliciently reduced. In other words, if a' Diesel engine of comparatively low compression ratio is supercharged the output can be increased maintaining the maximum pressure at a moderate extent. If, however, an ordinary centrifugal bloweris used as a super-charger for the engine the initial pressure is too low to start the engine when the revolution of the blower is slow. Thus a special method shouldbe taken for starting a Diesel engine of low compression ratio which can not be started by an usual manner.

This invention is-to provide a new method for the above purpose, and I have provided a valve for the super-charger of a four-cycle multicylinder Diesel engine to interrupt the air supply to the engine in case of its'starting and .change-over valve and cam devices for opera-ting some of the cylinders, for example, four cylinders among nine, as air compressors in such manner that air is sucked from the exhaust valve into the the cylinder 'and the compressed air is delivered to the suction manifold through .the suction valve of the same cylinder so thatthe compressed air may be supplied to the remaining cylinders through their suction valves to operate the engine according to the normal four cycles. Then the compression is effected once for each revolution in the compressor cylinders while the remaining five cylinders will operate as a fourcycle Diesel engine sucking air into each cylinder from the suction manifold once for two revolutions so that the five cylinders may be supplied with air twice of four cylinder volumes, viz. cylinder charges corresponding to the supercharge of 1.6 times and thus the higher compression pressure is obtained to start the engine easily.

My invention will he better'understood from the following description when considered in connection with the accompanying drawings,

and its scope will be pointed out "in the appended claims.

In the accompanying drawings Fig. 1 is a sectional view taken for explanationof the pinciple of operation of my invention; Fig. 2 is a sectional elevation of a cylinder of Diesel engine having'a valve gear used in carrying into effect my invention; Fig. 3 is a sectional side view thereof; F18. 4-is a front view of a modified form of the valve gear used in carrying into efl'e'ct my invention as applied to a radially arranged nine cylinder engine; Fig. 5 is a partial sectional view thereof;

and Fig. 6 is a perspective view showing a modifled form of change-over valve gear embodying my invention.

Referring to Fig. 1 of the accompanying draw- A ings, A1, A2, represent engine cylinders working on a normal four. cycle operation and B1, B2, are cylinders which can be converted into compressor cylinders when starting the engine. E represents exhaust valves; S are suction valves; I and I designate exhaust manifolds connected to the cylinders A1, A2, and

B1, B2, respectively through the exhaust ports 2 and 2'. 3 represents a suction manifold leading to the suction valves of each cylinder through the branched suction passages l. 5

represents a super-charger connected to the suc'-' tion manifold 3 and having a rotor 6. I is a control valve provided in the suction passage of the super-charger 5. Assume the cylinders .to be provided with changewver valve gears to operate these cylinders as the compressors when the engine is started by means of external power or some other prime mover such as an electric motor. In other words, the exhaust valves E of the cylinders B1 and Ba are used as the inlet valves and the suction valves S of these cylinders are used as the delivery valves when the .valve operating devices are changed-over. Then the-cylinders B1, B2, will be operated as the compressors by sucking air through the exhaust valve E and delivering the compressed air through the suction valve S and the suction passages 4 I to the suction manifold 3 so that the compressed air may be supplied to the cylinders A1, A2, when the suction valve S of such cylinders is opened. Thus sucking air from the exhaust valves and delivering through suction valves the compressed air into the suction manifold leading to the remaining three cylinders Ar, A: and A; as the combustion air so that viz, twice the normal volume of air is supplied into the cylinders A1, A2 and A3 and the engine can be easily started. The engine is driven in the above manner until it arrives at a certain highspeed and the super-charger can produce sufficiently high pressure, then the valve for the super-charger is opened and also the changeover cams for the cylinders B1, B2 and B3 are restored to the original positions and fuel is supplied to these cylinders, then the cylinders will be easily self-started as a Diesel engine.

. In Figs. 2 and 3, I have shown a change-over valve device for effecting the above described principle of operation of my invention. B1 is a cyl-' inder to be converted to a compressor. l represents a piston; l I a piston rod; i2 a crank shaft; and I2 the cam shaft. i4 and i5 represent valve operating rods for exhaust valves and suction valves respectively. 18 and I1 are hinged levers V acting on the valve stem I 8 biased by a spring l2. The cam shaft I3 is arranged to be shifted axially and has formed thereon special cams 20. f

and I5 independently of the axial shifting of the cam shaft II. In such arrangement the cylinder Hi can be converted to compressor operation by shifting the cam shaft l2 axially to the left in Fig. 3, then the cams 22 and 22 are used instead of the cams 22 and 2|, while the cams24 and 25 remain in operation.

In Figs. 4 and 5 I have shown another formof I change-over valve device applied to a nine-cylinder Diesel engine of radial arrangement. A1, A2, A3, As represent cylinders capable only of normal operation. Bl, B are cylinders to be converted as air compressors. having change-over valve gears. I4 is a rod for operating the exhaust valve and cooperating with a cam ring 26, on which are formed four cams 21 on the same circumference and another group of eight cams 28 for the compressor operations on the adjacent circumference. valve and cooperating with the cam ring 29, on which are formed four cams 20 on the same circumference and another group of eight cams 2! on the adjacent circumference. 22 represents a gear on the engine crank shaft. The cam rings 22 and 22 are made integral, but shown as having different diameters in Fig. 4 for the sake of clearness, but they may have the same diameter as shown in Fig. 5. The cam rings are driven in a direction opposite to the crank shaft by, means of gearings 22, 22 and 24 and at a speed of revolutions atone-eighth of that of the crank shaft. The cam ring is also mounted on the bearing 36 I5 is a rod for operating a suction- (Fig. 5) to be shifted axially by means of a strap 21. I

The operationof the valve gears shown in Figs. 4 and 5 is as follows: In the normal four cycle operations the earns 21 and 22 cooperate with the rods i4 and I5 for exhaust and suction valves respectively of the cylinders B1, B But when starting the cam rings 26 and are shifted axially, then the cams 28 and 2| cooperate with the valve operating rods l4 and I5 respectively. Accordingly the cylinders B1, B2, B are operated as air compressors sucking air into the cylinder through the exhaust valves and delivering the compressed air through the suction valves into the suction manifold repeating twice operations in one revolution of the crankshaft.

The same object of changing the valve operations can be attained by an arrangement of valve gears without shifting the cam shaft or cam ring as'in Figs. 3 and 5. One of such valve gears is shown in' Fig. 6, wherein 28 represents a cam ring provided with cam surfaces 22 and 40 cooperating with the cam rollers 4| and 42 respectively. The rollers 4| and 42 are mounted on one end of the parallel rods 42 and 44 respectively, the other end of these rods being connected to a sector arm 45. 46 represents springs. To thearm is joined a swinging rod 41 which is hinged to the valve operating rod 42 at 49. The arm 45 is curved along a circular arc having the radius equal to the length of the swinging rod 41. 50 represents a part of the shifting rod and 5| is a hinged lever acting on the valve spindle 52. If the rod, 41 is shifted along the sector arr'n 45 to the left end in Fig. 8 the valve will be operated by the cams 42,'while if it is shifted to the right end the valve will be controlled by the cams 39. Suppose now the cam 42 operates the valves for compressor operation and the cam 22 effects the valve action for ordinary four cycle Diesel engine, then if the rod 41 is moved from the left end position to the right the operation of the cylinders can be changedfrom air compressor to ordinary Diesel engine.

Though I have described in the foregoing a few examples embodying my invention, yet it will be understood that any desired number of cylinders out of a group of cylinders may be operated as air compressors at starting by the above described manner to supply-compressed air as the suction air into the other cylinders, thereby giving high initial pressure even at]! low speed running so as to facilitate the starting of the engine.

According to this invention, the super-charger of a four-cycle multl-cylinder Diesel engine may be of an ordinary centrifugal blower instead of a displacer type super-charger such as Roots blower or eccentric disc type blowers even if the compression ratio of the engine is low. By the present method the engine may be started with less torque than that necessary when all cylinders arestarted at the same time.

For engines designed for the compression ratio of 12 to 14, the super-charger is not necessary for converting the cylinders operated as air compressors at first into engine operation, but the object can be satisfactorily attained by merely bringing the engine speed up to a certain high speed. Accordingly this invention can be applied to the starting of four cycle multi-cylinder Diesel engine without super-charger if the compression ratio is not exceedingly low.

I claim:

l. A Diesel engine for operation at abnormally low compression ratio comprising a supercharger, a valve controlling the passage of air to said super-charger, engine cylinders having exhaust and suction valves, separate connections between said super-charger and the suction valves, a change-over gear for adjusting the valves of certain of the engine cylinders for converting the latter 'intocompressor cylinders to cause air to be drawn throughthe exhaust valves of the compressor cylinders and to be delivered through the suction valves thereof to the remaining enginev cylinders, thereby super-charging said remaining cylinders to facilitate selfstarting.

2. A method of starting fourcycle multiple cylinder Diesel engines having an abnormally low compression ratio such as 8 to 12 and a rotary blower as a super-charger and exhaust and suction valves and a change-over gear for said valves, consisting in closing the valve 01' the supercharger, driving the engine by external power, converting a suitable number of the engine cylinders into air compressors temporarily at the starting by adjusting said change-over gear to cause air to be drawn through the exhaust valves of the compressor cylinders and to be de-

Images