Patent GB-769333-A (GB)
Title: Arrangement for controlling compressed air or other driving motors for conveyors
IPC: F01B17/00
Filed: 1954-07-21
Abstract: 769,333. Conveyer systems. GREBE, K. July 21, 1954 [July 21, 1953], No. 21273/54. Class 104 (2). For the control of compressed air, electric or other motors in a conveyer system in which independent load-carrying belt sections are moved along the conveyer system the driving motors are automatically switched on and off by the belt sections in such manner that the direction of travel of a belt section arriving at a drive determines the direction of the motor for such drive just prior to engagement of the drive with the belt section. A belt section travelling in the direction of the arrow shown in Fig. 1 moves rollers 11 on the left-hand side of the Figure to rock a cam 12 anti-clockwise, the eccentric portion 13 of which raises a cone valve 15 to the fully open position to enable compressed air from a pipe 9 to enter a connection 8 via a chamber 16 and to close a chamber 17 in the valve 6. The compressed air passes from the connection 8 through a pipe 5 to the driving motor 1 and into a pipe 3 to exert a pressure on the smaller surface of a piston 18 to drive the motor 1 in one direction. The chanber 17 of the valve 6 being open to atmosphere, the chamber above the piston 18 in the reversing cylinder is connected through a pipe 4 and a connection 7 to a vent pipe 10. When the belt section travels in the reverse direction, Fig. 2, the rollers 11 on the right-hand side of the Figure are moved to the left and the eccentric portion 19, the lift of which is less than the portion 13, of the cam 12, partially raises the valve-actuating piston 14 to lift the valve cone 15 to open the chamber 16, to leave the chamber 17 open and in communication with the chamber 16 and to close the vent pipe 10. Compressed air now passes through the chamber 16 to the driving motor 1 and through the pipe 3 to the lower end of the reversing cylinder 2 and also through the chamber 17 via the pipe 4 to the upper end of the reversing cylinder 2. Since the surface area of the upper side of the piston is greater than that of the lower side the piston 18 is depressed and the driving motor 1 is reversed. The rollers 11 are held in the normal vertical inoperative position by a rod 24 pivotally connected to a sleeve 21, Fig. 4, and slidable through and projecting beyond a fixed guide. The rod 24 carries two springs, one between the fixed guide and the sleeve 21 and the other between the fixed guide and an abutment on the free end of the rod 24. When the rollers 11 are deflected from the vertical, one of the springs is compressed and subsequently returns the rollers to the vertical position. If it is desired to reverse the motor in an emergency and when the rollers 11 are deflected by a belt section, the screws 25 are released, the spindles 22 are retracted into the sleeve 21, the rollers 11 are swung to the opposite position and the spindles 22 are pulled outwardly of the sleeves 21 and then locked in position by the screws 25. In the arrangement shown in Fig. 5 the belt section passes from the lower run on the right of the Figure over a vertically operated switch point 26 through a single run section where it is driven by a drive 27 and then over another verticallyoperated switch-point to the'lower run on the left of the Figure. The belt section is turned through 180 degrees by a device 28 to discharge material conveyed thereby and is then engaged by drive 29 and passes over a returning station 30 to the upper run where its conveying surface is now uppermost. The belt section now passes over the switch-point 26<1>, the single run section where the drive 27 is now reversed, and the switch-point 26, to the upper run on the right. The runs on the right of the Figure may be arranged side-by-side, in which case the switchpoint 26 is horizontally-operated. The right- and left-hand runs may be identical. Since the direction of the drive 27 is determined by the belt section passing over the switch 26 in the lower position and the switch 26<1> in the upper position contacts 33, 33<1> primarily for the automatic control of the switch points may be also used to control the direction of the drive 27. Alternatively the contacts provided in the installation for blocking specific sections of the track when the switch points are in certain positions may be used to control the direction of the drive 27. In this case the direction of the drive 27 is independent of the sequence in which contacts 31, 31<1> are actuated and which switch the drive 27 on or off. The drive 29 which always rotates in the same direction is switched on by the actuation of a contact 32 and remains in operation after a contact 32<1> has been actuated until both contacts 32, 32<1> are released. In the arrangement shown in Fig. 6, in which the direction of the drive is reversed whilst the belt section is in engagement therewith the belt section approaches the system from the left of the Figure and actuates valve 34 to cause compressed air to pass through a pipe 36 to a control valve 40 which switches the driving motor on or off and at the same time enables compressed air to enter a by-pass 36<1>, which can be blocked by an auxiliary valve 34<1>, and into a chamber 38<1> through a pipe 38, to act on one side of a reversing piston 42. Should the belt section approach the system from the right, Fig. 7, a valve 35 is actuated to allow compressed air to pass to the control valve 40 through a pipe 37, a by-pass pipe 37<1> which can be blocked by an auxiliary valve 35<1>, and a branch pipe 39 leading to the other side of the reversing cylinder 41. To prevent compressed air passing from pipe 36 to pipe 37 and vice versa whereby the reversing piston would be acted upon on both sides simultaneously, non- return valves 43, 44 are arranged in the pipes 36, 37 before their junction. Non-return valves 45, 46 are also arranged between the two branches of the by-pass pipes 361 and 371. Upon actuation of the valve 34 by the belt section approaching from the left, Fig. 6, compressed air passes via the pipe 38 to the upper end of the reversing cylinder 41 and through a throttle 47 to the control valve 40. The lower side of the reversing cylinder 41 is vented via pipes 39, 37 and the non-return valve 46 is bypassed by the pipe 37<1>. The throttle 47 effects a delayed operation of the control valve 40 so that the driving motor is not switched on until its direction has been fixed by the actuation of the piston 42. Smooth starting of the driving motor is effected by the gradual opening of the control valve 40 through the action of the throttle 47. After, the lower chamber of the reversing cylinder 41 is vented via the pipe 39, the by-pass 37<1> is closed by the actuation of the valve 351 and the by-pass 361 is partially fed by the actuation of the valve 34; the complete blockage of the by-pass 361 being effected on release of the valve 34. The actuation of the valve 35, however, allows compressed air to flow through the pipe 37 to the control valve 40 so that the driving motor still continues to run even after the release of the valve 34. On release of the valve 34 the air pressure on each side of the piston 42 remains the same, the vent pipe 38 leading from the upper chamber 38<1> of cylinder 41 being blocked by the non-return valve 45 and the valve 341. On release of the valve 341 the chamber 38<1> is vented through pipes 38, 36 and 361 and the piston 42 is driven to the top of the cylinder 41 to reverse the direction of the drive. In the arrangement shown in Fig. 7 the belt section approaches from the right to actuate the valve 35, thereby setting the drive in motion in the reverse direction, the drive only changing its direction when the belt section no longer engages the valves 35, 341 and 35<1>. Hand actuation of the apparatus can be effected by inserting three-way cocks 48, 49 in the pipes 38, 39 so that either chamber 38<1> or 39<1> can be vented. A three-way cock 50 inserted in the pipe leading to the control valve 40 can be used to stop the drive by venting the pipes 36, 37. The drive can also be stopped after actuation of the valves 34, 35 and in spite of the non-return valves 43, 44 by a continuous slow venting of the pipe by way of a throttle 51 so that the control valve 40 closes when compressed air ceases to flow in pipes 36, 37. The control valve 40 comprises a piston 53 slidable in a cylinder 52 and connected by a piston-rod 54 to a valve 55 which effects a connection between a chamber 57 and a chamber 58 surrounding the cylinder 52. The piston 53 is normally held in the lowermost position by compressed air from a pipe 59, continually under pressure, entering the chamber 57 and closing the valve 55. The piston 53 on being raised by compressed air from pipes 36 or 37 entering the lower part of the cylinder 52, the upper part of the cylinder being vented through a pipe 56, opens the valve 55 to allow compressed air to pass from chamber 57 to chamber 58 and through a pipe 60 to the driving motor. In this arrangement the pressure balance between the chamber 57, 58 is quickly established and the driving motor is started rapidly. To effect a slow and gradual driving motor start the upper part of the cylinder 52 is vented through a throttle 61 in the pipe 56 into a cylinder 62 to delay the rise of the piston 53 and hence the opening of valve 55 and the pressure balance between the chambers 57, 58.