SLURRY PUMP

Abstract: A slurry pump has a hopper (1) containing slurry. A pumping cylinder (5) containing a piston (9) communicates with the hopper (1) through the hopper wall. A delivery tube (17) is swung into and out of register with the cylinder (5). Slurry is drawn into the cylinder (5) by the piston (9) and out through the delivery tube (17). The pump is controlled by a lever 68 which has a central neutral position and two operating positions. Dangerous moving parts are covered by a guard (62) mounted on hinges (64). An arm (74) on the guard (62) engages a slide (70) which has a channel (72). If the guard (62) is moved from its closed position, the arm (74) slides the slide (70) so that the control lever (68) enters the channel (72) and moves to its neutral position. The external moving parts include releasable clamping means (33) for sealing the junction of the delivery tube (17) and the cylinder (5) while slurry is being transferred from the cylinder (5) to the tube (17).

Description: The present invention relates to slurry pumps. A slurry pump is known from DE-A-2 447 054 which comprises a hopper, a pump cylinder communicating with the hopper through an opening in a first wall of the hopper, a pumping piston reciprocatable within the cylinder, drive means for the piston, a cranked delivery tube having a first end portion mounted in an aperture in a second wall of the hopper, the aperture having a central axis and the first end portion being pivotally mounted to swing about the central axis, means for swinging the delivery tube to move a second end of the delivery tube transversely into and out of register with the opening, a shaft coaxial with and pivotable about the central axis and extending through the first wall, a means connecting the delivery tube to the shaft in the region of the second end portion, and releasable clamping means comprising an actuator operable to apply a clamping force to the second end of the tube to clamp the second end to the periphery of the opening during transfer of slurry through the opening and to release the clamping force while the tube is swinging. Another slurry pump is known from DE-A-2 931 814 which discloses a hopper, a pumping cylinder communicating with the hopper through an opening in a first wall of the hopper, a pumping piston reciprocatable within the cylinder, drive means for the piston, a cranked delivery tube having a first end portion mounted in an aperture in a second wall of the hopper, the aperture having a central axis and the first end portion being pivotally mounted to swing about the central axis, means for swinging the delivery tube to move a second end of the delivery tube transversely into and out of register with the opening, a shaft coaxial with and pivotable about the central axis and extending through the first wall, an arm fixed to the second end portion and to the shaft, and releasable clamping means comprising an actuator operable to apply a clamping force to the second end of the tube to clamp the second end to the periphery of the opening during transfer of slurry through the opening and to substantially completely release the clamping force while the tube is swinging, the actuator being attached to the arm. In this specification the cylinder is inside the hopper and connected to the delivery tube by an arm, so that as the tube swings, the pressure cylinder moves through the slurry in the hopper. German patent application DE-A- 2 362 670 discloses a pump with a swinging delivery tube. The swinging end of the tube is permanently held against a hopper wall by means of a nut. This arrangement causes significant and undesirable wear. A first aspect of the invention is characterised in that the connecting means comprises an arm fixed to the second end portion and to the shaft, in that the actuator is located wholly outside the hopper and is arranged to act on the shaft to exert a force along the axis of the shaft, and in that the aperture in the second wall of the hopper is located below the opening in the first wall of the hopper. A second aspect of the invention is characterised in that the arm extends out of the top of the hopper, the clamping means, in use, acting between an outer wall surface of the hopper and the arm, and in that the aperture in the second wall of the hopper is located below the opening in the first wall of the hopper. The moving parts of slurry pumps with swinging delivery tubes present considerable dangers to workmen. Accordingly it is desirable to provide a safety mechanism whereby the dangers presented by the moving parts are minimised. In a preferred embodiment, a slurry pump according to the invention is further characterised by comprising a control member for controlling the drive means and having a neutral position in which the drive means are inoperative and a second position in which the drive means are operable, and a guard having a closed position in which the guard prevents access to a part of the slurry pump, and an open position in which the guard permits access, and characterised by a cam surface which is moved by movement of the guard from its closed position if it is not in ist neutral position and to retain the control member is in its neutral position until the guard has been returned to its closed position. An embodiment of the present invention will now be described by way of example and with reference to the accompanying drawings in which:- Figure 1 is a perspective view of a concrete pump, Figure 2 is an elevational view of the pump shown in Figure 1, and shows, in broken lines, a modification according to the invention, Figure 3 is a cross section of the pump along the line iii-iii in Figure 2, Figure 4 is a partial elevational view of the pump of Figures 1 to 3, adapted to incorporate the safety mechanism of the invention, Figure 5 is a partial plan view of the pump of Figure 4, Figure 6 is a partial sectional view of the pump of Figures 4 along the lines 7-7 in Figure 4, and Figure 7a, 7b shows the control member from the same viewpoint as Figure 6, in two alternative positions to that of Figure 6. The concrete pump shown in Figures 1 to 3 has a hopper 1. Two pump cylinders 5a, 5b communicate at one end with the interior of the hopper 1 through holes 7a, 7b in a wall 3 of the hopper. Two reciprocable pistons 9a, 9b are contained one in each pump cylinder 5a, 5b and are driven in opposite phase by hydraulic rams 11a, 11b which are supplied with pressurised fluid by a control systm 10, shown schematically in Figure 1. A motor-driven hydraulic pump 12 provides pressurised hydraulic fluid to the control system 10 from a reservoir 14. Then end wall 13 of the hopper, opposite to the wall 3, has an outlet port 15, below the level of the holes 7a, 7b. A cranked delivery tube 17 has a straight portion 17a which is journal mounted in the outlet port 15. The journal-mounted portion 17a is connected to a pipe line 16 by means of a swivel coupling 18 (Figure 2). The cranked portion 17b of the delivery tube 17 extends across the hopper 1, to the end wall 3. The delivery tube 17 terminating at the end wall 3, to form a swinging end 17c which is pivotally mounted on the hopper wall 3 by means of a supporting arm 19 and pivotal mounting 21. The axes of the pivotal mounting 21 and the journal mounting in the outlet port 15 are coincident, and so the delivery tube 17 is angularly displaceable about this axis. The swinging end 17c of the delivery tube 17 can be brought into and out of register with the holes 7a, 7b, alternately, by the piston rod 23 of a hydraulic ram 25 supplied by the control 10. The ram drives the supporting member 19 through the mounting 21 by means of a clevis connection 27 to an arm 29. The ram 25 is attached to the hopper 1 by means of a pivotal mounting 22 on an arm 24, see Figure 3, extending from one side wall of the hopper 1. Releasable clamping means are provided which when actuated clamp the swinging end of the delivery tube 17 to the hopper wall 3, around one or other of the holes 7a, 7b. The clamping means may be provided in a variety of ways. Figure 1 showns an extension of the supporting member 19 which circumvents and is clamped to the delivery tube and extends out of the top of the hopper 1. A rigid cross-member 33 projects from the top of the supporting member 19 above the wall 3 of the hopper 1. A hydrulic ram 31 is attached to the cross member 33, and has a piston rod 34 which projects towards the wall 3. When the ram 31 is actuated by the control system 10, the piston rod 34 is driven against the outer surface of the wall 3, and a force is transmitted through the cross-member 33 and the supporting member 19 to hold the swinging end of the delivery tube 17 in sealing contatct with the inner surface of the wall 3 around the hole 7a or 7b. When the control system 10 releases the actuating pressure, a spring returns the piston rod to its initial position. An alternative clamping means is shown in broken lines in Figure 2 and does not require the extension of the supporting member 19, or the integers attached thereto. A hydraulic ram 35 is mounted on the case 37 of the pump cylinders 5a, 5b, by means of a bracket 39. The piston rod 38 of the ram 35 is attached to the shaft of the pivotal mounting 21 by means of a swivel connection 41. When the ram 35 is actuated by the control system 10, the piston rod 38 is drawn away from the hopper, and pulls on the arm 19, through the mounting 21. The swinging end 17c of the delivery tube 11 is therefore pulled into sealing contact with the wall 3 around the respective hole 7a, 7b. To comply with safety requirements, guards must be placed around the external moving parts. The top of the hopper 1 is preferably covered with a grill through with slurry may be poured but which prevents workmen reaching into the hopper. The pump control lever could be arranged so that it passes through the guards and grill and be so shaped that it prevents the guards and grill from being removed except when the lever is in its "OFF" position. Alternatively as will be described in more detail, the pump control lever is arranged so that when the guards or grill are removed the lever is returned to its "OFF" position. In operation, when pumping concrete, a region below the level of the holes 7a, 7b, should be filled with sand. It is found that this sand remains in position and becomes covered by a thin skin of set cement or concrete. This prevents concrete from remaining static in the bottom of the hopper and thereby setting. The direction of movement of concrete during pumping is indicated in Figure 1 by arrows 30, 32. During the first half of a pumping cycle, concrete is drawn into the pump cylinder 5a from the hopper 1, in the direction shown by the arrows 30. Meanwhile the pump cylinder 5b expels concrete through the hole 7b into the delivery tube 17, which is clamped to the wall 3 by the clamping means (31, 35 or 47). The concrete then passes along the delivery tube, through the outlet port 15 and into the pipeline 16, in the direction shown by arrows 32. When the cylinder 5b is empty, the clamping means are released and the delivery tube 17 is swung by the ram 25 into register with the cylinder 5a. The clamping means are then re-engaged and the second half of the cycle commences during which the piston 9a pumps concrete through the delivery tube 17 to the pipeline 16. When the pump cylinder 5a is empty, the clamping means are released, the ram 25 swings the delivery tube back to its initial position, in register with cylinder 5b, and the cycle recommences. After pumping, the thin concrete skin formed over the sand may be broken with a rod and washed out with the sand and any concrete remaining, through the bottom of the hopper, which is formed with an opening 50 which is closed by a removable plate 51 (Figure 2). The rams 3, 31, 35, 47a and 47b which have been described as hydraulic could also be powered by one of the following means: pneumatics, electromagnetic devices, jackscrew threads, rack and pinion devices, ball screws or electromechanical actuators. The pump may be used in reverse, (by reversing the connections to the ram 25) to draw slurry into the pump through the port 15, and thence into the hopper 1. Similarly reverse pumping of water can be used to clean the pump after use. The safety mechanism whereby the pump control lever is returned to its "OFF" position when the guards and grill are removed will now be described with reference to Figures 4 to 7. Referring now to Figure 4, the hopper 1 is covered by a grill 60, shown by broken lines. A guard 62 covers the moving parts of the pump external to the hopper 1, during operation of the pump. The guard 62 is pivotally mounted on the pump by a hinge 64, so that it may be raised for access to the moving parts, for instance for maintenance. The guard can be raised through approximately 90° to the position indicated by chain-dotted lines in Figure 4. The grill 60 is pivotally mounted at 68 so that it can be raised through approximately 90° to the position indicated by chain - dotted lines in Figure 5. The raised grill allows access to the hopper for the purpose of clearing the hopper, for instance. The slurry pump is controlled by a manually operable control lever 68, which has at one end a handle 68a, and which has three detent positions to select forward pumping, reverse pumping and neutral or "OFF", respectively. Figures 6, 7a and 7b show the control lever positioned to select forward pumping, neutral and reverse pumping respectively. A forked strip 70 is mounted to be horizontally slidable between first and second extreme positions shown in solid and chain-dotted lines respectively in Figures 4 and 5. The forked strip 70 defines a channel 72 having an inner position in which the channel sides are parallel with each other and with the line along which the forked strip is movable, and an outer portion in which the channel sides (72a, 72b) widen towards the channel mouth. A level 74 is mounted on the guard 62 and, therefore pivots with the guard 62 about the axis of the hinges 64. The lever extends through an aperture 76 in the fork 70. As the guard is raised from the position shown in to the position shown in chain - dotted lines in Figure 4, the lever 74 rotates about the axis of the hinges 64 and bears on the forked strip 70 to slide the forked strip from the first to the second positions shown in Figure 5. The inner section of the channel 72 has position and width so as only to allow the forked strip to slide past the control lever 68, when the control lever is in its neutral position. If the lever is not in its neutral position when the guard is opened, the sides of the channel 72 act as cam surfaces on the lever to cause the lever to revert to its neutral position. If the lever is in its neutral position before the guard is opened, the lever remains in that position. The inner, parallel-sided portion of the channel prevents the lever being moved from its neutral position until the forked strip has been moved back to its first position, shown in solid lines, in response to the guard being closed, when the pump is again safe to be used. The pump is therefore, automatically switched off if the guard is raised. The pump is also automatically switched off if the grill is raised, as will now be described. A coupling arm 78 is attached to the guard 62 and, when the guard 62 and grill 60 are shut, extends above the grill 60. The coupling arm 78 is cranked and has a lower surface which is nearer to the grill 60 at the end of the arm remote from the guard 62 than at the end adjacent its point of attachment to the guard. A bar 80 is attached to the upper surface of the grill 60 and is generally parallel to the axis of the pivotal mounting 66 of the grill 60. When the grill 60 is raised, by means of a handle 81 integral with the grill, the bar 80 engages and runs along the underside of the coupling arm 78, thereby also causing the guard 62 to be raised. The grill 60 cannot be raised without the guard 62 being raised and, consequently, the grill 60 cannot be raised without the control lever being set to its neutral position, and the pump thereby switched off. The lever surface of the coupling arm 78 defines a detent recess 82 which can engage the bar 80 to lock the grill 60 in its open position (shown in chain-dotted lines in Figure 5). It will be seen from the above description that the pump cannot be operated unless both the grill and the guard are closed. The safety mechanism cannot be overridden or fail to operate. While the grill and the guard have been described as separate integers, it will be apparent that the grill could be integral with the guard. The coupling between the grill and the guard would not then be required.

Claims: 1. A slurry pump comprising a hopper (1), a pumping cylinder (5) communicating with the hopper (1) through an opening (7) in a first wall (3) of the hopper (1), a pumping piston (9) reciprocatable within the cylinder (5), drive means (11) for the piston (9), a cranked delivery tube (17) having a first end portion (17a) mounted in an aperture (15) in a second wall (13) of the hopper (1), the aperture (15) having a central axis and the first end portion (17a) being pivotally mounted to swing about the central axis, means (25, 29, 21, 19) for swinging the delivery tube (17) to move a second end (17c) of the delivery tube (17) transversely into and out of register with the opening (7), a shaft coaxial with and pivotable about the central axis and extending through the first wall (3), a means connecing the delivery tube to the shaft in the region of the second end portion (17c), and releasable clamping means (35, 38, 41) comprising an actuator (35) operable to apply a clamping force to the second end (17c) of the tube (17) to clamp the second end (17c) to the periphery of the opening (7) during transfer of slurry through the opening (7) and to release the clamping force while the tube (17) is swinging, characterised in that the connecting means comprises an arm (19) fixed to the second end portion (17c) and to the shaft, in that the actuator (35, Fig.2) is located wholly outside the hopper (1) and is arranged to act on the shaft to exert a force along the axis of the shaft, and in that the aperture (15) in the second wall (13) of the hopper is located below the opening (7) in the first wall of the hopper. 2. A slurry pump comprising a hopper (1), a pumping cylinder (5) communicating with the hopper (1) through an opening (7) in a first wall (3) of the hopper (1), a pumping piston (9) reciprocatable within the cylinder (5), drive means (11) for the piston (9), a cranked delivery tube (17) having a first end portion (17a) mounted in an aperture (15) in a second wall (13) of the hopper (1), the aperture (15) having a central axis and the first end portion (17a) being pivotally mounted to swing about the central axis, means (25, 29, 21, 19) for swinging the delivery tube (17) to move a second end (17c) of the delivery tube (17) transversely into and out of register with the opening (7), a shaft coaxial with and pivotable about the central axis and extending through the first wall (3), an arm (19) fixed to the second end portion (17c) and to the shaft, and releasable clamping means (33, 34, 31) comprising an actuator (31) operable to apply a clamping force to the second end (17c) of the tube (17) to clamp the second end (17c) to the periphery of the opening (7) during transfer of slurry through the opening (7) and to substantially completely release the clamping force while the tube (17) is swinging, the actuator (31) being attached to the arm (19) characterised in that the arm (19) extends out of the top of the hopper (1), the clamping means (33, 34, 31), in use, acting between an outer wall surface of the hopper (1) and the arm (19), and in that the aperture (15) in the second wall (13) of the hopper is located below the opening (7) in the first wall of the hopper. 3. A pump according to claim 1 or 2 characterised in that it comprises two pumping cylinders (5a, 5b) communicating with the hopper (1) through respective openings (7a, 7b) in the first wall (3), a pumping piston (9a, 9b) within each cylinder and drive means (11a, 11b) for each piston, and in that the tube swinging means (25, 29, 21 19) are arranged to swing the second end (17c) alternately into register with each opening (7a, 7b) and the clamping means (35, 38, 41 or 33, 34, 31 is controlled to perform a clamping action when the delivery tube (17) is in register with either opening (7a, 7b) and slurry is being pumped into the delivery tube (17) from the corresponding pump cylinder (5a, 5b). 4. A slurry pump according to any of claims 1 to 3, further characterised by comprising a control member (68) for controlling the drive means (11, 25) and having a neutral position in which the drive means (11, 25) are inoperative and a second position in which the drive means (11, 25) are operable, and a guard having a closed position in which the guard (62) prevents access to a part of the slurry pump, and an open position in which the guard (62) permits access, and characterised by a cam surface (72a) which is moved by movement of the guard (62) from its closed position to cause the control member (68) to adopt its neutral position if it is not in its neutral position and to retain the control member (68) in its neutral position until the guard (62) has been returned to its closed position. 5. A slurry pump according to claim 4, characterised by the control member (68) having positions selecting forward and reverse pumping on opposite sides of the neutral position, and two cam surfaces (72a, 72b) which are moved by movement of the guard (62) from its closed position to return the control member (68) to its neutral position if it is not in its neutral position, and to retain the control member (68) in its neutral position until the guard (62) has been returned to its closed position. 6. A pump according to claim 4 or 5, characterised in that the cam surface of surfaces (72a, 72b) are formed by a slide member (70), and the guard (62) carries an arm (74) which engages the slide member (70) to cause it to slide in response to movement of the guard (62).

Inventors: DWYER, ANTHONY FREDERICK
Applicants: HYDROSEAL CONCRETE PUMPS LIMITED
Application year: 1983
Main classification: F04B15
IPC codes: F04B15