US1757399A - Cylinder-head combustion chamber - Google Patents

Description

May 6, 1930. A. TAUB ,7

CYLINDER HEAD coMBus TIoncHmBE'R Filed Sept 21, 1927 2 Sheetsr-Sheet l gwuvmtfom J52 Jam;

May 6, 1930. A. TAUB CYLINDER HEAD COMBUSTION CHAMBER Filed Sept. '21, 1927 2 Sheets-Sheet 2 m gwuemto a J [21 721265 Patented May 6,

* UNITED STATES [PATENT OFFICE ALEX TAUB, OF DETBbI'I, MICHIGAN, ASSIGNOR TO GENERAL MOTORS CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELAWARE CYLINDER-HEAD COMBUSTION CHAMBER Application filed September 21, 1927. serial No. aaLo'za.

This invention relates to the combustion chambers of internal combustion reciprocating engines and is particularly applicable to engines in which the combustion space communicating with each cylinder. bore lies wholl or approximately within a space that Wonk? be bounded by an extension of the internal surface of the cylinder bore; it is particularly applicable to engines of the so-called over-head valve type.

Harshness or smoothness of an internal combustion engine depends upon the rate of pressure rise in the combustion chamber during a combustion period, and detonation depends upon the temperature of the unburned portion of the burning gas. It has been ascertained that rate of pressure rise and temperature of the last gas to burn during a combustion period can be controlled to -a considerable extent by combustion chamber form and the relative location of the point of ignition in the chamber in engines of L-head type, wherein a considerable volume of the combustion chamber is oif-set'laterally from the cylinder bore in order to provide room for valves at one side of the cylinder.

It is an object of this invention to apply. to over-head valve or other engines having the combustion space over the piston, the principles found effective in controlling rate of pressure rise and detonation producing temperatures in L-head engines.

The invention comprises a cylinder having a combustion chamber not offset materially from the cylinder bore, of contour and proportions calculated to reduce the maximum rate of pressure rise toward the end of the burning period, and to conduct heat away from that portion ofthe charge that is last to burn so rapidly as to keep it below th temperature at which it detonates.

In the accompanying drawings in which like reference characters indicate like parts throughout the several views:

Fig. 1 is a cross section through an engine cylinder embodying this invention;

Fig. 2 is a plan view of a head casting belonging to a cylinder block shown in section In in Fig. 1, a portion of the casting being shown block; 11 a head casting; 12 a piston adapted valves; 18 one of the poppet valves (in this in section one plane normal to the c linder axes as indicated by the line22 of ig. 3;

Fig. 3 is an elevation of a portion of a head casting of the form shown in Fig. 2, a art being shown in section on a plane inclu 'ng the cylinder axes, as indicated by the line 33 of Fig. 2, and

Fig. 4 is a view of the underside of a fragment of the head casting shown in the other views.

The particular engine illustrated in the drawing is a four-cylinder engine having the cylinder bores arranged upright in line or in tandem relation. The combustion chamber illustrated is, of course, applicable to reciprocating internal combustion en ines, whatever may be the position of the c hnder how axes with respect to a horizonta plane.

Therefore, in referrin to the combustion chamber and valves, asiaeing above and over the piston or cylinder bore, it is meant that they are opposed to the working face of the piston in w atever angular position the cylmders may be disposed and are confined approximately within a space bounded by the extension of the wall of the cylinder bore beyond the working face of the piston.

the drawing, 10 indicates a cylinder to reciprocate in cylinder bore 13; 17 the combustion chamber over the piston; 14 the usuai cam shaft; 15 one of the valve push rods operated by the cams on the cam shaft; 16 one of the rocker arms for unseating the case an intake valve) for controllin a port of communication between the cham lier and a manifold (not shown) 19 a stem attached to said valve andpressed upon by said rocker arm to 0 en the'valveand 20 a coil spring such as- 1s generally used for closing the valve. The drawing shows a'four-cylinder engine in which ad acent cylinders communicate with a common intake pocket as is indicated at 21. Each exhaust valve .ort communicates by a single passage 22 wit an exhaust manifold (not shown);

The combustion chamber 17 is disposed substantially over or above the working surface 1 of the plston 12. Although shown 1n the il- 100 lustrated embodiment as of somewhat great cross sectional area than the cylinder bore, or over-hanging it, the overhang is slight and a is not such as to substantially widen the head or cylinder block as comparedwith what is customary in the over-head valve type of engine. The presenceor absence of overhang as shown is not'material to the invention and depen'dsmainly on the compression and extent of valve movement required. The combustion chamber 17 comprises a thin space.

I at 23 where the area of wall surface to volume is relatively large shortly after the instant of firing when the piston is at or near the end of its compression stroke. At the opposite side of the chamber 17 from the thin space 23 there is a firing or ignition bay 24, ofl-set from the chamber as" shown in an upward direction. Tapped into this off-set portion or firing bay 24 is a spark plug 25, the ignitionpomts'bein therefore at considerable distance from te space 23. In the form shown,

flame travel, which isprogressive from the point of ignition, has to proceed around the corner 24 formed by the boundary wall ofbayc24 and the main portion of the chamber 17. By thetime the flame front reaches the distant (with reference to the ignition point) side of the chamber containing the thin space 23, there will be no unburned gas excepting that in front of the flame in the space 23 and that lying along the reentrant wall 26 which divides the layer of unburned gas in contact with itand causes the gas to flow laterally in opposite directions so that the unburned gasis smoothly deflected, glves up heat to the reentrant wall, and flows without eddying into the relativel thin space 23. Thus the last of the gas to e burned will have heat extracted from it by the large cooling surface in 1 contact with it as compared with the volume.

The temperature of the last gas to burn will,

therefore, be kept below the temperature at which it detonates under compressions considerably higher than is customary in automobile engines.

' As indicated at-27 the roof of the combustion chamber immediately in front of (as into the space 23.

The form of. combustion chamber illustrated and described enables the same results to be obtained in an over-head valve engine as have been obtained in-L- head engines as regards smoothness of operation and absence of detonation. By inspection of Fig. 1, it may be imagined that the typical combustion chamber of an L-head engine has been bent at an angle of 90 degrees, the valve ports having been shifted from the underside of the overhanging portion to a position in the roof of the chamber where the valves of over-head valve engines are usually placed. The usual over-head valve type of engine has the combustion chamber so compact that it is difficult to locate the point of ignition in such a position that the rate of pressure rise can be slow enough to prevent that harshness which occurs when the charge burns too quickly. By

reducing the space between the working face tially free from detonation and harshness,

even though using compressions considerably higher than the normal compressions in gasoline automobile engines of today. i

I claim: I 1. An engine cylinder having-a combustion chamber provided with a portion having intake and exhaust ports disposed in itsi'oof over the cylinder bore, an ignition bay ofl'set upward from the ported portion at one side of I the axis of the cylinder bore, and'a thin cooling space opposite the ignition bay at the other side of the axis of the cylinder bore, said cooling-space having a large ratio of wall surface to included volume, relative to the other portions of the chamber, for the purpose of maintaining the last. unburned portion of the burning gas below the temper-. ature at which detonation takes place.

' 2. An engine cylinder as defined in claim 1 in which the thin cooling space lies between the top of the piston and the roof ofthe chamber when the piston is at the end of its compression stroke.

3. An engine cylinder having a combustion chamber rovided with a portion having intake and exhaust ports disposed in itsroofover the cylinder bore, an ignition bay ofiset upwards from the ported portion at one side of the axis of the cylinder bore and a thin cooling space opposite the ignition bay at the other side of the axis of the cylinder bore, the side wall of the ported portion of the chamber adjacent the entrance to the cooling space having a reentrant surface facing the ignition bay. 0 4. An engine cylinder as defined 1n clamii 3 in which the height of the ported portion of the chamber increases adjacent the reentrant side wall whereby to afford an increased expansion space for the gases being forced toward the cooling space by themoying flame front.

5. An engine cylinder having a combustion chamber provided with intake and exhaust ports in the roof over the cylinder bore, an igmtion bay oflset upward from the ported portion at one side of the axis of the cylinder bore and a thin cooling space opposite 5 the ignition bay at the other side of sald axis;

said cooling space having a large ratio of' wall surfaceto included volume relative to the other portions of the chamber and said ported portion increasing in volume adjacent w to the entrance to the cooling space.

.6. An engine cylinder having a combustion chamber comprising a portion of relatively great depth and small ratio of wall surface to mcluded volume and a cooling space connecting therewith of relatively small depth and large ratio of wall space to included volume; said portion of relatively great depth having intake and exhaust ports communicating therewith; a sparking device in said portion of relatively great depth disposed ad'acent the side oppos1te the cooling space, sai portion of relatively great depth increasing in volume adjacent to vthe communication between it and said coolin space.

In testimony whereo I afiix my signa ture. a

. ALEX TAUB.

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