Patent GB-756640-A (GB)
Title: Improvements in or relating to intake silencers for internal combustion engines
IPC: F02M35/14
Filed: 1954-08-18
Abstract: 756,640. Intake silencers. HOUDAILLE-HERSHEY CORPORATION. Aug. 18, 1954 [Feb. 23, 1954], No. 24082/54. Class 7(2) [Also in Group XXVIII] In an intake silencer for an I.C. engine a volume attenuating chamber is defined by a casing 5, 6 having an opening for the entrance of sound waves developed in the engine to the chamber. and carrying a tuning tube at least one end of which opens-into the chamber and the intermediate portion of which is provided with an opening communicating with the atmosphere outside the casing. As shown in Fig. 2, the silencer surrounds the upper portion of a downdraught, single or dual carburetter 1 and the casing is in two parts secured together at 7, the upper part 6 being eccentric and projecting beyond the part 5 as indicated at 8. A circular outlet opening in the part 5 is defined by a flange 11 closely engaging the flange 2 of the carburetter and secured to an upstanding partition 12 the lower end of which is shaped to form with the flange 11 a seat for a gasket 13. Secured to the upper end of the partition 12 is an annular, cup-like container 14 for an air-cleaning liquid such as engine oil, the container at the junction thereof with the partition being shaped to provide a seat for a gasket 16. A depending filter-holding shell 19, 20 for an annular filter element 21 of curled cattle tail hair is secured to a removable cover 17 held in position by a wing nut 24 screwed on to a bolt 23 secured to the carburetter, and seating on a gasket 10 in a seating formed in the casing part 6, the cover having depending feet 22 abutting against the flanged upper end of the shell part 20. An enlarged opening 25 -in the bottom of the filter holder is covered by a screen 26 and the holder carries a downwardly-extending baffle 27 to meter the amount of oil carried into the filter element 21 by the air passing therethrough: The attenuating chamber is formed by the casing parts 5, 6, the partition 12, the wall 15 of the container 14 and the part 19 of the filter holder, and is in open communication with an annular air-inlet passage 28. Tuning of the chamber to a predetermined frequency or frequencies is made by providing in the upper part of the casing an arcuate partition 29 the intermediate portion of which is disposed opposite an air inlet duct 30; the partition forms a pair of tuning tubes 31, 32, Fig. 1, extending in opposite directions and terminating in open ends 33, 34, and the lengths of the tubes are varied as desired. In modifications, (a), Fig. 3 (not shown), the bottom of the container 14 bears against the gasket 16 which is carried by the baffle 27 and the lower part of the filter-holding shell 19. and a sloping partition, secured to an intermediate part of the bottom of the container 14 and the base of the casing 5, 6 adjacent the point where the latter accommodates the gasket 13, is substituted for the partition 12, (b) the tuning tube is formed by a channelshaped member 38, Fig. 5, secured to the exterior of the casing 5, 6a and provided with an opening 39 to receive an air-inlet duct 30, the side branches of the tube communicating with the interior of the casing by way of elongated slots 42 cut in the wall of the casing part 6a; a sloping partition, secured at 45, 46 to the bottom of the container 14, has a lower inwardly channelled portion to accommodate a' gasket 47 and a flange 48 extending downwardly to the seat of the gasket 13, (c), Fig. 6 (not shown), the part 6 of the casing is removable together with the filter element 21, there being on that casing part a beaded or rolled edge which seats on a gasket accommodated in a peripheral channel formed on the upper marginal edge of the casing part 5. and (d) the attenuating chamber is divided by a partition 52, Fig. 7, the lower portion 54 of the chamber being acoustically coupled to the path of the sound waves emanating from the engine by a series of openings 55 in the partition 12a, a skirt 56 defining a passageway 57 the width of which, together with the length of the skirt, may be varied to effect the required tuning of the chamber 54; the upper portion of the chamber is tuned by varying the length of the tubes 31, 32, shown in Fig: 1.