Patent GB-319303-A (GB)
Title: Improvements relating to exhaust steam injectors
IPC: F04F5/46
Filed: 1928-06-20
Abstract: 319,303. Metcalfe, R. D., and Metcalfe, J. C., (Griffin, j.). June 20, 1928. Giffard injectors; regulating or controlling action.-In an injector primarily operated by exhaust steam and wherein the admission of water and exhaust steam is governed by fluid pressure controlled valves, the supply conduit 4, Fig. 2, for live steam to operate the injector and control the valves is controlled by a starting-valve 21 and manually controlled means 48 - - 51 is arranged for regulating the water supply, means actuated by the water regulating means controlling the starting-valve 21. The admission of low pressure live steam is regulated in accordance with the water supply. In an injector of the type described in Specification 2133/08 the conduits 16, 10, Fig. 2, for supplying water and exhaust steam are rontrolled respectively by a valve of the type described in Specification 260,918 and by the valve 25. actuated by live steam, the starting-valve 21 being operatively associated with the regulating means 48 - - 51 which are manually operated by a single control. The injector comprises a housing 9, a steam-chamber 10 to which exhaust steam is admitted through the valve 11 passing thence through the main low-pressure steam nozzle 14, a combining cone 15, a water inlet 16 and a nozzle 17 for the supplementary (high-pressure) live steam. The valve 25 controlling the admission of exhaust steam and auxiliary (low-pressure) live steam to the chamber 10 comprises a piston 28, loosely mounted in an open-ended cylinder 27 formed with valve seats at its opposite ends and a double seated valve head 29 one face engaging the seat at the lower end of cylinder 27 and the other the seat surrounding the port 30 between the steam chamber 31 and the chamber 10. A check valve 33 is adapted to engage the seat at the upper end of cylinder 27 and to form with the piston 28 a steam chamber 34. If the engine is in operation and exhaust steam is available it enters at 36 and forces the check valve 33 to seat as shown. Live steam entering the chamber 31 passes to the cylinder 27 and leaking past the piston 28 builds up a pressure in the chamber 34 thereby forces the valve 25 to close the port 30 and cut off live steam from the chamber 10. Live steam from cylinder 27 passes through passage 37 and acts on the piston 13 to open the exhaust valve 11 thereby' admitting exhaust steam to chamber 10. If the engine throttle is closed the failure of steam pressure at 36 permits the check valve 33 to rise and release the pressure in chamber 34, the valve 25 shifting to its upper seat and auxiliary steam, throttled at 24, enters chamber 10. The steam supply to the passage 37 is also cut off and the spring 12 closes the valve 11. The starting valve 21 is similar in construction to valve 25 comprising a piston 38, a cylinder 39, a double seated valve head 40 and a check valve 42. The high-pressure steam inlet passage 18 communicates through the port 20 with a second steam passage 19 and thence by branch passages 22. 23 to the nozzle 17 and by the choke port 24 to the valve 25. The valve controlling the admission of water is supplied with steam through passages 22, 45. The amount of water supplied is regulated by varying the area of the passage 47 the steam nozzle 14 being movable longitudinally through an eccentric pin 51 on a plate 50 carried by a spindle 48 having an operating lever 49. A passage 53 connects the steam passage 18 with the upper portion of a chamber 54 from the bottom of which a passage 55 leads to the chamber 43 and a passage 56 to the low pressure steam chamber 10. The spindle 48 having flattened sides 57 carries a disc valve 58 provided with a port 59 and with an arcuate recess 60 in its lower face. Assuming the nozzle 14 set as in Fig. 2 to give the minimum water inlet 47, admission of steam to the passage 18 will automatically shut off the injector by operation of the valve 21, steam passing through the passages 53, 59, 55. 43 to seat the check valve 42, steam also leaking past the piston 38 to build up pressure in the chamber 44 and force the valve 21 to close the port 20. On moving the nozzle 14 to give the maximum inlet 47 the recess 60 is brought into register with passage 55 and the pressure in the chamber 43 released through 55, 60, 56, the valve 21 moves to open the port 20 and high pressure steam enters the passage 19 passing thence through passages 22, 23. 45 to the nozzle 17 and to open the water valve, and also the chamber 31 where, according to engine conditions, it opens the valve 11 or supplies auxiliary live steam to the chamber 10. In a modification, the fixed choke 24 is omitted and a variable choke comprising a valve-member 61, Fig. 5. on the spindle 48 provided to regulate automatically the amount of auxiliary live steam supplied in accordance with the size of the water inlet 47. In a further modification, the port 20 is controlled by a mechanically actuated starting valve 62, Fig. 7, the stem 63 of which is slotted at 65. A wedge 68 passes through the slot 65 and is pivoted to a lever 70 on the spindle 48, the position shown corresponding to the minimum water inlet. As the spindle 48 is rotated to give a larger inlet the wedge 68 moves to the right to open the valve 62 against steam pressure, rotation in the opposite direction causes the port 69 to act against the lower face 66 to lower the valve the final closure being accomplished by steam in the passage 18.