Patent GB-710383-A (GB)
Title: Improvements in presses for the extraction of oils, fats and the like
IPC: B30B9/06
Filed: 1952-03-06
Abstract: 710,383. Presses for separating liquids from solids. POWELL, A. J. March 6, 1952 [March 21, 1951], No. 5837/52. Class 46 Apparatus for oil extraction and the like comprises a cylindrical curb the wall of which is formed with apertures through which the expressed liquid is discharged, a reciprocable plunger coaxial with and operating in the curb, the plunger when fully retracted being withdrawn from the adjacent end of the curb to permit of the supply to the latter of material to be compressed, and a reciprocable closure arranged coaxially with the curb to coact with the opposite (discharge) end of the latter, the closure being retractable to enable the compressed material to be expelled by further projecting the plunger. The apparatus is preferably provided with means whereby it may be operated continuously on the successive batch principle. Fig. 1 shows a hydraulically-operated apparatus at the beginning of a cycle. A cam-shaft 32 having cams (not shown) for operating valves 31 and 21 and a cam 36 for operating a switch 35 is rotated continuously. The valve 21 has just been rotated to permit pressure liquid to be pumped from a reservoir 26 along pipes 22 and 20 to the outer end of a pressing ram cylinder 17. The force acting upon the head 18<SP>1</SP> overcomes that acting in the narrow annular space 23 on the inner side of the head which space is permanently connected by pipe 22 with liquid under pressure. At the same time the switch 35 is closed whereby a motor 16 drives a screw feeder 14 in a hopper 13. The ram 18 moves inwardly and may continue to do so without interruption but preferably it is reciprocated several times through a short distance to tamp the material in a curb 10. The feeder 14 is preferably operated each time the ram is retracted at this stage. Retraction is effected by movement of the valve 21 to connect the outer end of the cylinder 17 to an exhaust pipe 21<SP>1</SP>, whereupon the continuing pressure in the annular space 23 moves the ram 18 to the right. After filling, the pressing ram is moved continuously inwards for an appreciable period until it attains the position of Fig 4 Throughout these parts of the cycle the valve 31 governing an abutment ram cylinder 28 has remained closed so that liquid in the cylinder and in the pipe 30 has locked the abutment ram 29 in its fully projected position (Figs. 1 and 4). At the stage of Fig. 4 the valve 31 is opened by its cam 34 (not shown), the cylinder 28 thus being placed in communication with the pipe 22 supplying pressure liquid. The abutment ram 29 is then subjected to the same pressure intensity as the pressing ram but being of smaller crosssectional area is forced towards its retracted position by the ram 18 through the compressed cake. The cake is thus expelled (Fig. 5) and forced outwardly over the conical surface of the abutment ram (still under pressure), thereby being broken. The outer end of the pressing ram cylinder is then connected to exhaust whereupon the pressure acting behind the abutment ram 29 and in the annular chamber 23, restores the rams to the position of Fig. 1. The valve 31 is then closed to lock the abutment ram 29 in position. The hopper and/or the rams may be heated to facilitate oil extraction. In the modification of Fig. 7 the ram 18 has an axial extension 18<SP>2</SP> slidable in the ram 29. Also, a non-return valve 41 is arranged between the pipe 22 and valve 31 so that when the latter is open to pressure the abutment ram cannot be forced backwards by the pressing ram 18. The cylinder 28 can be connected to exhaust 21<SP>1</SP> by the valve 31 for retraction of abutment ram 29. The ram 29 in this modification thus need not be of smaller diameter than the ram 18. In the modification of Fig. 8 the press instead of being operated on a fixed time basis is controlled automatically in response to variations in the pressure in cylinders 17 and 28 so as to perform the required operations in the desired sequence though the time of each cycle is not fixed. Control is effected by the pump 24, a main valve 50, pilot valve 60 and relief valve 70. In Fig. 8 the pressing ram 18 is about to commence its pressing stroke while the ram 29 is locked in its fully extended position by pressure liquid in cylinder 28, pipe 30, valve 70, pipe 64 and chamber 57, which also maintains pilot valve member 61 in its upper position. The ram 18 thus continues its projecting movement until it engages and compresses the material in the curb 10, the progressively increasing pressure on the abutment ram causing progressive rising of pressure in cylinder 28. When this pressure reaches a predetermined value valve member 71 is moved to the right against spring 72, placing the cylinder 28 out of communication with pipe 64 and in communication with exhaust compartment 73 provided with a restricted discharge orifice 74. Ram 29 is thus forced back, but pressure in cylinder 28 is maintained by 74 so that considerable resistance is offered to movement of ram 29. When ram 29 reaches abutment 28' the pressure of oil in the cylinder 28 is relieved. Valve member 71 is then returned to the normal position (Fig. 8), as a result of which the pressure in pipe 64 is reduced so that valve member 61 is moved downwards by its spring 62 so that compartment 55 of the main valve is opened to exhaust by pipe 56 and opening 60<SP>1</SP>. The pressure exerted on the plunger 52 at the right-hand of the piston valve 51 then moves the latter to the left so as to connect the outer end of the cylinder 17 to a discharge passage 50<SP>1</SP> and the pipe 64 to supply pipe 22. The ram 18 thus commences its retracting stroke because the inner end of the cylinder 17 is permanently connected to the supply pipe. During the initial portion of the return movement of ram 18, ram 29 is being projected and thus remains in contact with it until it is arrested by the curb 10, Fig. 8. When the pressing ram reaches the end of its retracting stroke, engaging abutment 17<SP>1</SP>, pressure in the pipe 22 progressively increases so that the pilot valve member 61 is again raised by pressure in pipe 64. The compartment 55 of the main valve is thus once more opened to pump pressure 24 so that valve member 51 moves to the right as in Fig. 8 and another cycle of operations commences.