Патент USA US2412478код для вставки
mg, m, 1946. ' J, $1M ' 2,412,478 STEAM vAC'I‘UATED PILOT CONTROLLED DISTRIBUTION VALVE FOR STEAM‘ ENGINES Filed Dec. 28, 1944 2,412,478 Patented Dec. 10, _ 1946 UNITED STATES PATENT Tor-"Flee ‘ STEAM ACTUATED PILOT CONTROLLED DISTRIBUTION VALVE FOR STEAM EN GINES James Sim, Cathcart, Glasgow, Scotland, assign or to G. & J. Weir, Limited, Glasgow, Scotland, a corporation of Great Britain Application December 28, 1944, Serial No. 570,183 In Great Britain January 8, 1944 2 Claims. (01. 121-157) 1 This invention applies to steam distributing valves of the type in which a main shuttle valve is reciprocated by steam pressure under the control of an auxiliary mechanically actuated valve sliding on the back of the main valve. Examples of this type are represented in Figs. 1, 2, and 3 of the speci?cation of British Letters Patent No. 3,723 of 1394 and in Figs. 1 to 9 of the speci?cation of British Letters Patent No. 1,023 of 1881, and in a modernized form in the speci ?cation of United States Letters Patent No. 2,093,963. With the present day increase in boiler pres sures and the high superheat temperatures now being used, difficulties, particularly excessive . 2 a . chined back'face. The valve spindle g passes through the centre of the auxiliary valve. The spindle, where it passes through the auxiliary valve, is square in section and is a ?t on the sides with clearance front and back so that the auxiliary valve can bed down on the shuttle valve back face but cannot, at the same time, be moved sideways by the shuttle valve when the latter is in motion. Two holes a‘ are drilled through the auxiliary valve 1‘ to provide relief for steam leak age at the back of the auxiliary valve 1‘. A ?oat ing ring it is arranged on the back of and slides on the valve 1‘ and bounds a space I which is brought under exhaust pressure by connection to the exhaust system of the auxiliary valve and shuttle valve through the holes it The space I wear, are experienced with steam slide valves of is closed by the cover 112. The ring 7c is an easy the type described in the speci?cations of the sliding ?t in the body of the casing 11. Grooves n said British Letters Patent. These difficulties are provided to allow high pressure steam to act are aggravated by the modern demand that the exhaust from auxiliary engines should be oil 20 on the top of the ring is and press the ring against the back of the auxiliary valve and thus free. These requirements demand a steam slide valve which will operate satisfactorily with high steam pressure and superheat, without lubricat ing oil, and without being subject to excessive wear on the sliding surfaces. The present invention consists of an arrange ment of parts, particularly applicable to the construction described in the speci?cation of the aforementioned British Patent No. 3,723 of 1894., prevent high pressure steam leaking into the space Z between the ring and the back of the auxiliary valve 1‘. The intensity of pressure between the ring R: and the back of the auxiliary valve 1‘ may be re duced to a satisfactory amount by the construc tion shown in Fig. 3. In Fig. 3 an internal ?angego is shown as formed solid with the ring is. A recess p is formed in the face of the ?ange o, and holes (1 are drilled through from the bottom of the recess p.' This operation is obtained at the highest pressures construction increases the sliding area of the ring and degrees of superheat without the need for it in contact with the back of the auxiliary valve internal lubrication. Figs. 1, 2, 3, 4 and 5 are sectional views illus 35 1‘ without causing any increase in total loading from the high pressure steam pressing on the trating the invention as applied to the construc ring is. The intensity of sliding pressure can tion according to the aforementioned British therefore be controlled to any desired amount Patent No. 3,723 of 1894. by the selection of suitable proportions. In Figs. 1 and 2 a is the valve chest casing Leakage of steam into the space Z at the outer with inlet port 8 and exhaust port 9, b and c the 40 end or the end remote from the auxiliary valve steam ports to the top and bottom of the steam may be prevented by means known per se, such cylinder driving the pump, d is the main steam as shown in Figs. 3, 4 and 5. valve or shuttle valve having steam ports I)’, c’ In Fig. 3 a ?exible metallic plate or disc 1‘ is and an exhaust port a, e are bells or small cylin ders which embrace the ends of the shuttle Valve, 45 shownjointed to the cover an. The high pressure steam admitted by the grooves 11, presses the and provide operating cylinders for the reciproé plate 1 against the outer edge of the ring is and cation of the shuttle valve. 1‘ is the auxiliary prevents the leakage of steam into the space 1. valve which slides on the back face of the shuttle In Fig. 4 a packed stuf?ng box or gland s is valve d. The valve J‘ is operated by the valve spindle g driven in usual manner from the valve 50 shown incorporated in the cover m to prevent the leakage of steam into the space Z. gear levers of the pump. The ‘valve 1‘ is a sliding In Fig. 5 normal type piston rings t are shown, ?t between the collar h and nuts 1‘ on the valve housed in the cover m and adapted to ?t within spindle g to ensure that the valve 1‘ will bed down the ring lc to prevent the leakage of steam into on the back face of the shuttle valve (1. \ The auxiliary valve 1‘ is provided with a ma 65 the space I. and so disposed as to reduce the loading on the sliding surfaces to such a value that satisfactory 2,412,478 3 4 The sliding faces of the shuttle valve 11 and the auxiliary valve f can be entirely relieved of loading by equalising the cross-sectional areas What is claimed is: 1. In a steam distribution valve of the type referred to, the combination with a valve casing of the exhaust cavity u of the shuttle valve, of having a steam port and an exhaust port, of a the exhaust cavity 0 of the auxiliary valve 1‘ shuttle Valve operative in said casing and pro and of the cavity Z which is under exhaust pres vided with steam inlet and exhaust ports and sure because of its connection with the cavity an exhaust cavity, an auxiliary valve slideable 11. by way of the holes 7'. The loading of these on the back face of said shuttle valve, leaving ‘faces would be entirely relieved if the ring it an exhaust space between the back of said shut were solid with the body of the chest a, but this 10 tle valve and said casing, said auxiliary valve would not be a good practical construction due being provided with holes adapted to communi to the precision necessary in manufacture; but cate with said exhaust cavity, a cover for said by making the ring is separate and an easy ?t exhaust space, and a ?oating ring bounding said in the chest a there is obtained a loading of the exhaust space laterally, one end of said ring sliding faces which depends on the thickness 15 bearing on the back face of said auxiliary valve, chosen for the ring is and is thus controllable. said ring being in engaging relation with said A certain loading is desirable and is that just cover, the effective cross-sectional area bounded necessary to hold the faces in contact. by said ring being approximately equal to the It will be understood that the whole of the exhaust port area of said shuttle valve. interior of the chest is under high steam pres 20 2. The combination claimed in claim 1 includ sure so that unbalance is caused solely by ex ing means to prevent steam leakage into the haust ports or cavities which are under exhaust exhaust space bounded by the ring. pressure. JAMES SIM.