US2578932A - Exhaust device for fluid flowing at high velocity - Google Patents

Description

Dec. 18, 1951 O mz ETAL 2,578,932

EXHAUST DEVICE FOR FLUID FLOWING AT HIGH-VELOCITY Filed April 22, 1948 FIqSZIII 1nven+ous= Julius O. Hinze Cornelia Si-Hlebroer Patented Dec. 18, 1951 EXHAUST DEVICE FOR FLUID FLOWING AT HIGH VELOCITY Julius 0. Hinze and Cornelis Stillebroer, Delft,

Netherlands, assignors to Shell Development Company, San Francisc of Delaware 0, Calil.'., a corporation Application April 22, 1948, Serial No. 22,684

I In the Netherlands May 1, 1947 V i This invention relates to devices-for exhausting fluids flowing at high velocity under pressure through a substantially square bend into a medium at lower pressure. In one specific application, the device may be used in internal combustion engines, such as two-stroke cycle and fourstroke cycle piston engines, eitherspark-ignition or compression-ignition, for discharging exhaust gases from the engine cylinder to the atmosphere or into an exhaust manifold, wherein a lower pressure prevails. More particularly, the invention is concerned with a valve-controlled exhaust device suitable for use in engines wherein the exhaust gases must be deflected through a substantially right angle turn after passing the exhaust valve.

It is known'to be of great importance to keep the flow resistance oflfered to the exhaust gases by such a bend as low as possible. 'since this resistance will uniavorably affect the power output of the engine. Hence, it is an object of the invention to provide an exhaust device for discharging fluid flowing at high velocity through a substantially square bend, wherein the flow resistance is made as small as considerations of space and constructions will allow. A iurther object is to provide a valve-controlled discharge device suitable for discharging combustion gases from a piston engine through an exhaust channel which has a bend which is substantially a 12 Claims. (Cl. 60-29) right angle wherein flow resistance is materially reduced.

According to the invention, the cross-section of the exhaust channel, starting from a circular shape near its inlet end (i. e., near the exhaust port of the engine) gradually passes into crosssections the contours of which have straight or substantially straight portions on the side outside of the bend, while the longitudinal section of the wall on the outside of the bend has a contour showing two essentially straight segments forming an angle. In other words: the wall of the channel at the outside of the bend i flattened, so that at this side the wall is essentially flat and shows a buckle in longitudinal section. The part of the flat wall up to the buckle is almost perpendicular to the plane or the circular cross-section near the inlet end, while the other part, beyond the buckle, is substantially parallel to said plane, 1. e., it forms only a slight angle with said plane. The channel preferably ha a constriction near its circular section at the inlet end and widens slightly and gradually from said constriction toward the inlet end or exhaust port.

and in the part or the channel beyond the bend (toward the discharge end of the exhaust channel) while the passage beyond the bend proper will be larger than that of the circular section. It has been found that when using such a shape the exhaust channel has a resistance to the flow of gas which is considerably smaller than the resistance of a channel of commensurate size in which the part leading from the exhaust port or valve to beyond the bend proper has a circular or substantially circular cross-section.

In the design of internal combustion engines the location of the outlet of the exhaust channel with respect to the valve-controlled exhaust port is usually determined by considerations of space. If the wall of the exhaust channel outside of the bend is shaped so that a longitudinal section thereof shows a contour consisting of two substantially straight parts forming an angle of with each other, the distance Irom the valve-controlled exhaust port to the wall of the exhaust channel opposite to it, measured along the axis of the exhaust port, will often become excessively large when the location of the final outlet of the exhaust channel is otherwise fixed, as by considerations of space. As the valve stem extends along this axis and the valve stem guide must project from the said opposite wall, the non-guided and uncooled part of the exhaust valve stem will in such situationsbecome undesirably long. According to this invention this drawback may be overcome by making the angle between the said two substantially straight contour segments in the longitudinal section of the outer wall larger than 90"; up to about 135". preferably between and The invention will be better understood by reference to the accompanying drawing iorming a part of this specification and showing one specific embodiment of the invention, wherein:

Fig. I is a longitudinal sectional view of a part of a cylinder head provided with an exhaust channel according to the invention;

Figs. II, III, IV, V, VI and VII are contours of the exhaust channel when viewed in cross-section on the lines bearing corresponding Roman numbers in Fig. I; and

Fig. VIII is the contour of the exhaust channel when viewed in a section taken on line VIII-VIII on Fig. I, i. e., in the axis or the exhaust port and perpendicular to the longitudinal section.

In Figs. 11 to VIII only the contours oi the sections are shown, the valve stem and valve stem Preferably. the channel is given a substantially guide being omitted.

3. The valve chest or cyl der head I is intended for use on an air-compressing, two-stroke engine, e. g., of the type operating with compressionignition and having a combustion chamber at the end of the cylinder the end wall of which is closed by the lower, annular face la of the cylinder head. The lower face of the cylinder head is provided with an exhaust port controlled by a central poppet valve 2 which has a valve stem extending along the axis of the exhaust port and guided by a valve-guide 3. The cylinder head is provided with spaces 4 through which cooling fluid may be circulated The cylinder headvis provided with a wall structure defining an exhaust channel 5 which has its inlet at the exhaust port (at the valve 2) and its outlet at section VII. It will be notedthat the channel makes a bend to the right through substantially a right angle, dividing the channel into an inlet part (i. e., the vertical part between the valve 2 and the bend) and an outlet part (i. e., the slightly inclined, essentially horizontal part between the bend and the outlet end). The wall shown in Fig. I to the left and above the channel proper is referred to as the wall on the outside of the bend, these walls being indicated by the letters a and b.

The exhaust channel according to the invention is circular at the section II, near the exhaust port, which forms the inlet to the channel and is also circular. Between the exhaust valve and the section II the channel is generally circular, but is slightly contracted as shown at h in Fig. VIII, forming a throat or constriction of oblate form, it being noted that the channel walls are not contracted in Fig. I. It is, however, also within the scope of the invention to use a circular throat, or to omit the constriction entirely. In this part the channel walls are shaped to conform as far as possible to the jet shape assumed by the exhaust gases after they have passed the exhaust valve.

From the section II onwards the channel wall on the outside of the bend, indicated at a, c, and d. is flattened gradually; this flattening is such that points on the extreme ouside of the bend (i. e., on the extreme left in Fig. I) of all sections up to and including section IV lie on a straight line, this line being perpendicular or substantially perpendicular to the plane of the exhaust port (i. e., being vertical in Fig. I). The channel wall is also gradually flattened at the sides of the channel towards the bend, whereby the channel gradually assumes a substantially rectangular shape. In the neighborhood of section VI the wall on the outside of the bend changes direction comparatively sharply, forming an angle with only a slight rounding, passing into a part which slopes slightly and has a faint bend toward the discharge end, as indicated at b, the curvature, in longitudinal section, being concave toward the exhaust port (i. e., concave toward the inside of the bend). The wall opposite, on the inside of the bend, in the longitudinal section shown. has a contour that is curved gradually and convexly toward the said angle, the curvature extending through an arc of approxi mately 90. The knee of the bend is, therefore, gradually curved or rounded on the inside wall and angular at the outside wall. The decrease in the cross-sectional flow area between sections III and V caused by the valve stem and valve stem guide 3, is compensated for by gradually increasing the distance between the sides of the channel walls between sections II and V, as shown more particularly in Fig. VIII. Sections V, VI and VIII show how the cross section gradually assumes the shape of a rectangle with rounded corners. It will be noted that between the bend (section IV) and the outlet (section VII) the outer wall shows a cross-sectional contour, indicated at d, e, f and g, which is first substantially straight, then convex inwardly, and finally again substantiallystraight. This arrangement permits the valve guide to be cooled for a greater extent, and is preferred but may be omitted.

The wall segment b on the outside of the bend in the outlet part of the exhaust channel, i. e.,

vthe roof is shown to slope upwardly gradually, at an angle of about 19 to the plane of the exhaust port; in other words, it makes an angle of about 119 with the wall segment a and with the axis of the exhaust port. By this arrangement the valve guide 3 is considerably nearer to the exhaust port than would be the case if this roof were horizontal. The non-guided and uncooled part of the valve stem is, therefore, correspondingly shorter.

We claim as our invention:

1. An exhaust device for a fluid flowing at high velocity and under pressure into a medium at lower pressure, which comprises a wall structure defining a tubular exhaust channel, said channel having a substantially square bend intermediate thereto, the cross section of said channel being circular at its inlet end and passing from said inlet end gradually into cross sections having con ours with substantially straight portions on the side outside of said bend, and the longitudinal section of the wall on the outside of the bend having a contour of two essentially straight segments forming an angle.

2. The exhaust device according to claim 1 wherein the cross section of the channel is substantially rectangular at the bend and beyond the bend.

3. The exhaust device according to claim 2 wherein the cross section of the channel between said bend and the outlet of the channel changes gradually so that the portion of the cross-sectional contour outside of the bend is substantially straight at the bend, and is successively inwardly convex and again substantially straight beyond the bend.

4. The exhaust device according to claim 1 wherein the cross sectional area of said channel, starting at the inlet end, contracts to a constriction between said inlet end and said substantially square bend and thereafter increases gradually and the cross-section of the channel at said bend has a substantially straight contour on the side outside of said bend.

5. An exhaust device for a fluid flowing at high velocity and under pressure into a medium at lower pressure, which comprises a wall structure defining a tubular exhaust channel, said channel having a substantially square bend intermediate thereto, the cross-section of said chan nel being circular at its inlet end and passing gradually between said inlet end and said bend into cross-sections having contours with substantially straight portions on the outside of the bend, and the longitudinal section of the wall on the outside of the bend having a contour of two essentially straight segments forming an angle.

6. An exhaust device according to claim 5 wherein the longitudinal section of the wall on the inside of the bend has a contour that is curved gradually through an arc of approximately at the knee of the bend convexly toward said angle in the wall on the outside of the bend.

7. A valve-controlled exhaust device for a piston engine comprising a wall defining a tubular exhaust channel, said channel having a substantially square bend intermediate thereto dividing the channel into an inlet part and a discharge part, an exhaust valve at the end of the inlet part away from said bend, a valve stem for said valve extending through the inlet part of said channel and through the wall of the exhaust part on the side thereof outside of the bend, the cross section of said inlet part of the channel being circular near said exhaust valve and passing from said valve gradually into cross sections having contours with substantially straight portions on the side outside of said bend and the longitudinal section of the wall on the outside of the bend having a contour of two essentially straight segments forming an angle.

8. The valve-controlled exhaust device according to claim '7 wherein the inlet part of the channel is circular in cross section near said valve and changes gradually to a substantially rectangular cross section at said bend.

9. The valve-controlled exhaust device according to claim 8 wherein the cross section of the outlet part of the channel is substantially rectangular and the portion of the cross sectional contour outside of the bend is inwardly convex intermediate the ends of said outlet part.

10. The valve-controlled exhaust device according to claim 7 wherein the inlet part of the channel has a constriction of substantially circular cross section near to and beyond said inlet valve and the cross sectional area increases gradually from said constriction to said bend.

11. A valve-controlled exhaust device for a piston engine comprising a wall structure defining a tubular exhaust channel, said channel having a substantially square bend intermediate thereto dividing the channel into an inlet part and a discharge part, an exhaust valve at the end of the inlet part away from said bend, a valve stem for said valve extending substantially coaxially through said inlet part and through the wall of the exhaust part on the side thereof outside of the bend, the cross section of said channel being circular near said exhaust valve and passing from said valve gradually into cross sections at the bend having contours with substantially straight portions on the side outside of said bend, the cross-sectional area of said channel increasing gradually from a section is said inlet part in advance of the bend at least to a point in the discharge part beyond the bend and the longitudinal section of the wall on the outside of the bend having a contour of two essentially straight segments forming an angle between about 90 and 135.

12. The valve-controlled exhaust device according to claim 11 wherein the angle between said segments is between 100 and 120.

JULIUS O. HINZE. CORNELIS STILL-EBROER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS (Addition to No. 833,256)

OTHER REFERENCES Ser. No. 215,792, Neugebauer et al. (A. P. C.), published Apr. 2'7, 1943.

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