COOLED VALVE SEAT INSERT, PREFERABLY FOR EXHAUST VALVES FOR DIESEL ENGINES

Abstract: A cooled valve seat insert (4) for an exhaust valve (2) for a Diesel engine comprises means for circulating cooling medium adjacent the valve seat (3) of the insert (4). In order to avoid a circumferentially extending cavity in the insert at the seat (3) of the insert and in order to secure a well defined guiding of the cooling medium, the means for circulating the cooling medium consist of a number of blind holes (17) distributed along a circle. The bottoms (18) of the holes (17) are arranged adjacent the valve seat (3) and the blind holes open into an annular duct (10) in the insert (4). By means of guiding baffles (19) inserted into the blind holes (17), the holes (17) are divided into a feeding duct (21) and a return duct (22). The feeding ducts and the return ducts communicate at the bottoms (18) of the holes (17). The annular duct (10) is by partition means (60) divided into cooling medium inlet and cooling medium outlet chambers (61 and 62) which communicate with the feeding ducts and the return ducts (21 and 22, respectively) of the blind holes (17).

Description: Cooled valve seat insert, preferably for exhaust valves for Diesel engines. The present invention relates to a valve seat insert, pre¬ ferably for Diesel engines, wherein the insert is provided with means for circulating cooling medium adjacent the valve seat of the insert concerned. It belongs to the prior art to provide valve seat inserts with a cϊrcumferentϊally extending cooling chamber which extends around the stationary seat of the valve and which is fed in different ways with a cooling medium in such a way that the cooling medium is circulated through the circumferentϊaliy extending chamber, no matter whether the inserts are constructed as socalled valve baskets with guϊdϊngs for the stem of the exhaust valve, or are in the form of separate bottom elements which support the stationary seat of the valve and are clamped between the cylinder head of the engine and the housing for the spindle of the exhaust valve. The insert according to the present invention is character¬ ized in that the means for circulating the cooling liquid comprise blind holes, the bottoms of which are arranged adjacent the valve seat of the insert concerned and which open into an annular duct in the insert, the blind holes being by means of guiding baffles insert¬ ed therein divided into a feeding duct and a return duct which • - communicate at the bottoms of the blind holes concerned, and in that the annular duct by partition means is divided into cooling medium inlet and cooling medium outlet chambers which communicate with the feeding ducts and the return ducts, respectively, of the blind holes . By means of such a structure a cϊrcumferentϊally extending cooling chamber extending in the insert around the stationary seat of the valve is avoided and simultaneously a well defined guiding of the cooling medium into and out of the blind holes is secured in a simple way due to the guiding baffles of the blind holes and the partition means of the annular duct. According to an embodiment of the invention the guiding baffles may be inserted generally radially in the blind holes with respect to the longitudinal axis of the corresponding valve, and the partition means may consist of parts of the guiding baffles having the same circumferential shape as the annular duct. This embodiment is advantageous because it is achieved that the guiding baffles and the partition means may be manufactured integrally with each other and the shaping and the arrangement of the guiding baffles result in that a cooling medium which flows to a cooling medium inlet chamber in the annular duct will be forced to flow into and out of blind holes following each other and along a generally meander shaped path of flow. Another advantageous embodiment of the valve seat insert according to the invention is characterized in that the guiding baff¬ les are inserted in the blind holes generally in the circumferential direction around the longitudinal axis of the corresponding valve, and that the partition means consist of a generally cylindrical guid¬ ing sheet integrally with the guiding baffles and which is inserted between the upper and lower walls of the annular duct. This embodi¬ ment is advantageous in that the cylindrical guiding sheet in a simple way provides a coupling in parallel of the feeding ducts and the return ducts of the blind holes in such a way that all the blind holes cool the insert in the same way. A further embodiment of the valve seat insert is according to the invention characterized in that annular ducts are formed along the separation surface between an upper part and a lower part which are welded together along the outer and inner surfaces of the Insert, and in that the insert is clamped into the cylinder head of the en¬ gine in such a way that the clamping causes compressϊve stresses in • - the outer weld with the direction of the stresses extending generally parallel with the longitudinal axis of the corresponding valve. By means of such structure it is achieved that the insert will not be considerably weakened due to the fact that the outer weld, as men¬ tioned, is under compressive stresses and the inner weld will also due to the heating which it will receive during the operation of the engine be subjected to compressive stresses due to the heat expan- sions of the inner surface of the insert. Said in other words, it is avoided that the heat expansion to which the inner surface is sub¬ jected may be transmitted to the weld along the outer surface and weaken the same. This embodiment is particularly advantageous in case where the inserts of an existing engine are to be provided with the cooling arrangement according to the present invention. In case the insert is clamped between the cylinder head of the engine and a valve housing for the corresponding valve, the valve housing may, preferably, according to a further embodiment of the invention be provided with a number of cooling medium inlet ducts and cooling medium outlet ducts communicating with the cooling medium inlet and cooling medium outlet chambers in the annular duct via ducts provided in the upper part and evenly distributed along the circumference of the annular duct. By means of such structure a very even cooling is achieved as regards the part of the insert which supports the stationary valve seat in the case where the blind holes are traversed in series because a cooling medium stream will traverse only a comparatively small part of the blind holes in series and accordingly it is very limited how great a temperature difference will result from the cooling medium has been fed into a cooling medium inlet chamber in the annular duct, and until the cooling medium leaves a cooling medium outlet chamber. The invention will hereinafter be further explained with reference to the drawings, wherein Figure 1 shows a part of an axial cross-section through a cylinder head containing a first embodiment of the valve seat insert according to the invention, Figure 2 shows a development of a part of a cross-section according to line 1 1 -1 1 in* Figure 1 , Figure 3 shows a part of an axial cross-section through a cylinder head containing another embodiment of the valve seat insert according to the invention, and Figure 4 shows a development of a part of a cross-section according to line IV-IV in Figure 3. In the drawings 1 is a cylinder head for a Diesel engine viz. that part of the cylinder head which surrounds one of the ex¬ haust valves 2 of the engines. It will be understood that Figures 1 and 3 for the sake of clarity show only one half of the corresponding exhaust valve 2. The exhaust valve 2 cooperates with a stationary valve seat 3 which is welded to the lower end of an insert which in general is provided with reference numeral 4. The valve seat insert 4 is arranged in a bore in the cylinder head 1 , and the wall of the bore is provided with reference numeral 5. At the upper end of the bore 5 a shoulder 6 is arranged which serves as support surface for a shoulder 7 which extends around the circumference of the insert 4. According to the embodiments shown in the drawings, the insert 4 is clamped against the shoulder 6 by means of bolts (not shown) which connect the valve housing 8 of the corresponding valve 2 and the cylinder head 1 of the engine. According to the embodiments shown in the drawings, the insert 4 is in the form of a bottom element which is clamped, in the way explained, between the valve housing 8 and the cylinder head 1 . However, it should be noticed that the present invention equally well may be used in connection with a valve seat insert in the form of a valve basket. The insert 4 is provided with an annular duct 10 which according to the embodiments shown is arranged at the separation surface 11 between an upper part 12 and a lower part 13 for the in¬ serts concerned, and the parts 12 and 13 are mutually connected by means of an inner weld 14 and an outer weld 15. Before the welding together of the upper part 12 and the lower part 13, generally vertical blind holes 17 have been drilled from the bottom of the annular duct 10 equally distributed around the circumference of the insert and the bottoms 18 of the blind holes are .positioned immediately adjacent the valve seat 3, however in such a way that the strength of the insert is not unduly reduced . According to the embodiment shown in Figures 1 and 2 a guiding baffle 19 is inserted in each of the blind holes 17 with the lower edge 20 of the baffle ending at a small distance from the - bottom 18 of the corresponding blind hole in such a way that each blind hole 17 is divided into a feeding duct 21 and a return duct 22. According to the embodiment shown on Figures 1 and 2, the guiding baffles 19 are so inserted that they extend generally in radial planes, i.e. In planes which contain the longitudinal axis of the correspond¬ ing valve. Opposite each guiding baffle 19, a partition 24 is arranged in the annular duct 10 as it appears from Fig . 2 so as to prevent direct passage of cooling medium past the corresponding blind hole and instead cause the cooling medium to follow a meander formed path as indicated by means of arrows 26 in Fig. 2. According to the embodiment shown in Figures 1 and 2, the guiding baffles 19 and the partitions 24 are manufactured Integrally with each other and before the welding together of the upper part 12 and the lower part 13 the partition part has been inserted into the part of the annular duct 10 extending In the upper part 12 in such a way that the guiding baffles 19 simultaneously, during the putting together of the upper part and the lower part, will serve as guides for the upper and the lower parts. As previously mentioned, according to the embodiments shown in the drawings, the insert is clamped against the shoulder 6 in the cylinder head 1 by means of bolts (not shown) which secure the valve housing 8 with respect to the cylinder head, and the valve housing 8 presses on the insert by means of an annular protrusion 28 which engages the circumferentially extending shoulder 29 at the insert. This circumferentially extending shoulder 29 extends, as seen in the axial direction of the valve, generally aligned with the outer weld 15 and, accordingly, the outer weld will , after the insert has been mounted, be subjected to compressive stresses which, generally, extend in the longitudinal direction of the valve. On the contrary, the radially innermost part of the insert has a clearance, as shown at 30, with respect to the valve housing and, accordingly, the radially innermost part of the insert may expand in the longitudinal direction of the valve when the inner part is heated by the hot exhaust gases. Accordingly, it is avoided that the expansion in the longitudinal direction of the valve to which the radially innermost part will be subjected during heating, will be transmitted to the outermost part of the insert which, as previously explained, is clamped axϊally aligned with the weld 15 in such a way that the outer weld constantly will be subjected to compressive stresses. • - - According to the embodiment shown in Figures 1 and 2, the annular duct 10 is fed with cooling medium through a number of cooling medium inlet ducts 34 arranged in the valve housing 8 and communicating with ducts 36 arranged In the upper part 12 of the valve insert. When a comparatively big Diesel engine is concerned, e.g . four cooling medium inlet ducts 34 may be used which means that four cooling medium inlet chambers 37, Fig . 2, which are posi- tϊoned offset 90 with respect to each other in the circumferential direction of the annular duct 10, are fed with cooling medium. Be¬ tween the cooling medium inlet ducts 36, cooling medium outlet ducts (not shown) are arranged in the valve housing 8 and each of the cooling medium outlet ducts communicates with a cooling medium outlet duct (not shown) in the insert corresponding to the ducts 36 but arranged between the ducts 36. Accordingly, the cooling medium outlet ducts communicate with cooling medium outlet chambers (not shown In Fig . 2) which are arranged halfway between the cooling medium inlet chambers 37. In Fig. 2 a cooling medium inlet duct 36 OR] is shown together with the corresponding cooling medium inlet cham¬ ber 37 which is defined between two adjacent partitions, and from the arrows 26 in Fig . 2 it will be understood that the cooling medium which is supplied through such a duct and such a cooling medium inlet chamber 37 will be divided into two streams which flow away from each other from each cooling medium inlet chamber 37 in the annular duct 10, so that each of said streams flows to an adjacent cooling medium outlet chamber. According to the embodiment shown In Figures 1 and 2, the outlet ducts open, as indicated by dotted lines 38 in Fig . 1 , into a cooling medium outlet duct 40 arranged in the valve housing 8. Due to the comparatively close arrangement of the cooling medium inlet chambers 37 and the corresponding cooling medium outlet chambers, a very even cooling of the area of the insert posϊ- tioned adjacent the seat 3 is achieved because a small number of blind holes only will be traversed in series . According to the embodiments shown In the drawings, the cylinder head 1 is cooled by means of a cooling medium circulated through a system of cooling ducts 42,44, an annular cooling chamber 46 which surrounds the insert and ducts 48. The cooling medium used for cooling the insert may appropriately be diverged from the cooling medium circulating through the cylinder head. - • In order to achieve a leakage-free transfer of cooling me¬ dium between the inlet ducts 34 and 36 (and in a corresponding way between the outlet ducts) at the two abutment surfaces 28 and 29, a recess 50 is provided in the abutment surface 29 opposite each of the ducts in the upper part 12 and sealing rings 52 are positioned in the recesses 50. The recesses are mutually connected in the circum¬ ferential direction of the insert by means of a shallow groove having a depth which is smaller than the depth of the recesses, and the parts of the groove extending between the sealing rings 52 are connected with the outer surface of the insert by means of telltale ducts in such a way that it is possible by means of the telltale ducts to ascertain whether a leakage exists at any of the sealings 52, both as regards the cooling medium and as regards exhaust gas. As regards the embodiment of the insert according to the Invention shown in Figures 3 and 4, the same reference numerals have been used therein as in Figures 1 and 2 as regards correspond¬ ing parts . According to the embodiment shown in Figures 3 and 4, the guiding baffles 19 are inserted into the blind holes 17 so that the guiding baffles 19 extend in the circumferential direction, i.e. in direction around the longitudinal axis of the corresponding valve. The partition means arranged in the annular duct 10 consists of a generally cylindrical guiding metal sheet 60 manufactured integrally with the guiding baffles 19 and extending between the upper and lower walls of the annular duct 10 so as to divide the annular duct 10 into two chambers viz. a cooling medium inlet chamber 61 and a cooling medium outlet chamber 62. In the same way as explained with respect to the embodiment according to Figures 1 and 2, the cooling medium inlet chamber 61 communicates with cooling medium inlet ducts 34 in the valve housing 8 via cooling medium inlet ducts 36 in the insert and the cooling medium inlet ducts 36 open into the inner- most part of the annular duct 10. From this part the cooling medium flows downwardly, below the lower edges 20 of the guiding baffles 19 and upwardly into the outermost part of the annular chamber 10, from which the cooling medium is conducted through cooling medium outlet ducts 64 indicated by means of broken lines in Fig * . 3 in the insert, and which are connected with the cooling medium outlet duct 30 in the valve housing 8 opening into an annular chamber 40 in the valve housing 8. Also according to the embodiment shown in Figures - 3 and 4, the cooling medium inlet ducts and the cooling medium outlet ducts are equally distributed in the circumferential direction in such a way that the cooling medium inlet chamber 61 is fed at positions which are offset with respect to the positions at which cooling medium is guided out from the cooling medium outlet chamber 62. Said in other words, according to the embodiment shown in Figures 3 and 4, the blind holes 17 are coupled in parallel in such a way that each blind hole is traversed by a corresponding partial stream of cooling medium.

Claims: a i m s 1. Cooled valve seat insert (4), preferably for exhaust valves for Diesel engines, wherein the insert (4) is provided with means for circulating cooling medium adjacent the valve seat (3) of the Insert (4) concerned, c h a r a c t e r i z e d in that the means for circulating the cooling liquid comprise blind holes (17), the bottoms (18) of which are arranged adjacent the valve seat (3) of the insert (4) concerned and which open into an annular duct (10) in the insert (4), the blind holes (17) being by means of guϊd- ing baffles (19) inserted therein divided into a feeding duct (21) and a return duct (22) which communicate at the bottoms (18) of the blind holes (17) concerned, and in that the annular duct (10) by partition means (24,60) is divided into cooling medium inlet and cooling medium outlet chambers (37;61,62) which communicate with the feeding ducts (21) and the return ducts (22), respectively, of the blind holes (17). 2. Valve seat insert according to claim 1, c h a r a c ¬ t e r i z e d In that the guiding baffles (19) are inserted generally • radially in the blind holes (17) with respect to the longitudinal axis of the corresponding valve, and that the partition means (24) consist of parts of the guiding baffles (19) having the same circumferential shape as the annular duct (10). • • 3. Valve seat insert according to claim 1, c h a r a c ¬ t e r i z e d in that the guiding baffles (19) are inserted In the blind holes (17) generally in the circumferential direction around the longitudinal axis of the corresponding valve, and that the partition means consist of a generally cylindrical guiding sheet (60) integrally with the guiding baffles (19) and which is inserted between the upper and lower walls of the annular duct (10). 4. Valve seat Insert according to claim 1, c h a r a c ¬ t e r i z e d in that the annular duct (10) is formed along the separation surface (11) between an upper part (12) and a lower part (13) which are welded together along the outer surface (at 15) and the inner surface (at 14) of the insert (4), and in that the insert (4) Is clamped into the cylinder head (1) of the engine in such a way that the clamping causes compressive stresses in the outer weld (15) with the direction of the stresses extending generally parallel with the longitudinal axis (5) of the corresponding valve (2). 5. Valve seat insert according to claims 2 and 4, and wherein the insert (4) is clamped between the cylinder head (1) of the engine and a valve housing (8) belonging to the valve (2) con¬ cerned, c h a r a c t e r i z e d in that the valve housing (8) is provided with a number of cooling medium inlet ducts (34) and cooling medium outlet ducts (38) communicating with the cooling medium inlet and cooling medium outlet chambers (37;61,62) in the annular duct (10) via ducts (36) provided in the upper part (12) and evenly distributed along the circumference of the annular duct (10).

Inventors: JOHANSEN JAN BECHMANN, JOHANSEN, JAN, BECHMANN
Applicants: INT POWER ENG AS, INTERNATIONAL POWER ENGINEERING A/S
Application year: 1982
Main classification: F01L3
IPC codes: F01L3, F01P3, F02B3, F02F1