Patent GB-933540-A (GB)
Title: Cleaning of eggs with divided abrasive material
Inventor: BUCKLEY PETER LEWIS BERESFORD
IPC: A01K43/00
Filed: 1960-10-26
Abstract: 933,540. Cleaning eggs. HARTLEY ELECTROMOTIVES Ltd., and SALOPIAN INDUSTRIES (METALS) Ltd. Jan. 26, 1962 [Oct. 26, 1960; Jan. 24, 1962], Nos. 36776/60 and 2665/62. Class 60. Eggs are cleaned by subjecting them to the action of an air stream carrying divided abrasive material entrained by the air stream as it passes in a generally vertical direction the lower end of an inclined supporting plate down which the abrasive material runs under gravity, the air stream then flowing at reduced velocity in the upper part of a closed container in which the inclined surface is located so that most of the abrasive material falls out on to the said surface before the air is extracted from the container through a screen of dimensions such as to prevent the abrasive material leaving the container. A casing 11 is hinged at one end to a cabinet 10 so that it may be lifted off for cleaning purposes, the junction between the casing and the upper surface of the cabinet being sealed by gaskets of foamed rubber or synthetic plastics material. The casing has a front observation window 12 and side apertures 13, 14 for the insertion and removal of eggs. The apertures are preferably closed by flaps or sleeves of rubber or synthetic plastics material. Within the casing 11 are two side by side egg-cleaning positions, each formed by a tray 15 shaped to form an inclined supporting surface 16 for the abrasive grit running down towards a slot 17 in the base of the tray 15 and a backing plate 18 on the other side of the slot 17. The backing plate 18 is covered with a sheet 19 of abrasive material. The slot 17 is narrow and elongated parallel to the backing plate 18. Each of the slots 17 is connected through a nozzle 20 and pipe 21 to a separate blower 22 mounted on a panel 23 in the cabinet 10. When the blowers are switched on upwardly-directed air streams rise from the slots 17 adjacent the lower ends of the supporting surfaces 16 and the grit down each of these surfaces is entrained by the air stream. An egg 24 is inserted through the aperture 13 or 14 and placed in the air stream. The weight of the egg is supported by the air stream and the egg is cleaned by the impact on it of the grit carried by the air stream; the egg also tends to be rotated by the effect of the air stream with its entrained grit. When, due to fluctuations in the air stream, the egg falls it rubs against the abrasive sheet 19, thus assisting the cleaning. After the air stream has passed the egg it spreads out in the upper part of the container and the entrained grit drops out on to the inclined supporting surfaces 16. The air is withdrawn through a screen 25, which prevents the escape of grit, and a dust collector 26 mounted below the back of the casing 11 within the cabinet 10. The screen 25 may have a rubber-coated baffle mounted in front of it to prevent impact of grit on the screen. The dust collector 26 consists of a washable plastic box, one wall 27 of which is formed by a fine mesh screen. The air is exhausted from the casing 11 through the screen 25 and dust collector 26 by an exhauster 28 mounted on the panel 23. The blowers 21, 22 deliver large volumes of low pressure and the exhauster is of such capacity as to maintain the interior of the casing 11 at a pressure of 2-3 inch water gauge below atmospheric pressure so as to prevent the escape of dirt- and dust-laden air from the casing. Restrictor flaps are preferably provided to prevent access of grit from the inclined supporting surfaces 16 to the nozzles 20 and the pipes 21 when the air supply to the slots 17 is cut-off accidentally or otherwise, the flaps being operated by a three-position lever serving also to control the motor driving the blowers 22. The lever is moved from stop position to an intermediate position so that the motor is given time to run up to speed, the flaps remaining closed. With the motor running at speed the lever is moved to a third position to open the flaps. It is stated that a fresh egg will rotate slowly in the air stream near the jet during cleaning, while an egg which is not fresh to the extent that the contents are adhering to the shell will not rotate. In a modification, Fig. 3, the closed container has an upper part 30, a lower part 31 and a central part 32 in the form of a trough having inclined walls 33 leading down to a slot-like opening 34 bounded by vertical walls 35. A number of fan-shaped nozzles 36 with rectangular mouths are arranged in line within the upper part 30 and extend down into the central part 32 to the level of the lower ends of the inclined walls 33. The nozzles are supplied with air from a blower 37 through a common supply pipe 38. The lower end of the opening 34 is closed by a flap 39 when the apparatus is not in use. Eggs 40 are fed through the lower part 31 under the opening 34 on rails 41. The latter may be rotated at about 150 r.p.m. in the same direction causing the eggs to rotate and to advance in the direction of their smaller ends. Preferably, however, the rails are provided with spiral ridges of about 2 inch pitch, e.g. by winding a spiral of wire on a rod and coating the assembly with rubber or plastic, and rotated at about 30 r.p.m. Eggs enter and leave the lower part 31 through inlet and outlet apertures masked with rubber flaps or the like. After the blower 37 has been switched on the shutter 39 is opened, e.g. automatically, and the eggs subjected to the air stream from the nozzles 36 with entrained grit. The air stream passes by return pipe 42 into the upper part 30, the junction between the lower part 31 and the pipe 42 is convergent to ensure that the air stream has sufficient velocity to carry all the grit and dirt into the upper part 30. As the air stream enters the upper part 30 its velocity is reduced and the grit falls out through a wire gauze screen 43 on to the walls 33, the screen having a mesh size approximately four times the diameter of the grit particles. The blower 37 withdraws air from the upper part 30 through a nylon mesh screen 44 and a dust trap including a filter cloth 46. A valve 47 in the supply pipe 38 creates a small air bleed so that the rate at which air is removed exceeds that at which it is supplied through the nozzles whereby a reduced pressure is maintained in the container to prevent the escape of dust-laden air. In both embodiments, the grit is aluminium oxide grit in a mixture of 80 and 90 mesh grain size.