Abstract:
A two-cylinder slurry pump ( 1 ) includes: a filling tank ( 2 ) for receiving thick matter; an agitator whose shaft ( 11 ) is placed in the filling tank ( 2 ), and a pivoting sleeve valve ( 16 ) fitted in the filling tank ( 2 ) which regulates the alternating intake and delivery strokes of the delivery cylinder. This pump also has an entry branch and an exit branch ( 15 ) pivotingly connected with the delivery piping ( 19 ). In accordance with the invention, the entry openings ( 46, 45 ) of the delivery cylinders ( 34, 35 ) are positioned behind the back wall ( 5 ) of the filling tank, and the exit branch ( 15 ) is positioned between the agitator shaft ( 11 ) and the back wall ( 5 ).

Description:
DESCRIPTION 
     The invention concerns a two cylinder slurry pump in accordance with the heading of the claim  1 . 
     The slurry pump as per the invention serves to convey materials or mixes thereof at a consistency between muddy and viscous which could contain fixed particles of a particular concentration. An example of a material mix of this kind is concrete in which the fixed particles are grains of sand or gravel. Such pumps convey the slurry under pressure, by way of their alternating suction and feed cylinders, through a pressure pipe. In doing so, one of the cylinder&#39;s upstream feed hoppers serves to supply the suction feed cylinder with a sufficient amount of the slurry. 
     Most slurry has a tendency, especially when still, to solidify. This can be a consequence of sediment. Other separation tendencies can occur when feeding concrete which can lead to the premature solidifying of the concrete. That is why, with the slurry pump as per the invention, the feed hopper has an agitator which, on the one hand, keeps the slurry moving in the container and also feeds it to the openings of the feed cylinder so that this cannot suck in any air during the normal operation. Hence the shaft of the agitator is arranged in the feed hopper and supports the agitator tools which bring about a feed effect in the direction of the cylinder openings and have the general shape of working paddles. 
     A sleeve valve serves to drive the feed cylinder openings in the two cylinder slurry pump as per the invention, which forms the end of the pressure pipe but is however linked with this. The free end of the sleeve valve moves with the supply of drive energy between the two openings of the feed cylinder in the feed and suction stroke of its pistons so that the feeding cylinder presses the slurry into the inlet arm of the sleeve valve, while the opening of the other feed cylinder is cleared, which means it is in direct contact with the slurry contained within the feed cylinder and sucks it in. The slurry, which is fed under pressure in the inlet arm, ends up in the outlet arm of the sleeve valve and then flows immediately from this into the pressure pipe. 
     For various reasons, especially however if the two cylinder slurry pump as per the invention is mobile as a vehicle pump, the need arises to limit the height of the feed hopper. One then requires an adequate feed volume, a proportionally scaled width of the feed hopper and a funnel-shaped incline at least of its front wall, i.e. the wall which is arranged on the outside of the extension of the feed cylinder, while the rear wall forms a boundary of the feed hopper to the feed cylinders. The arrangement of the sleeve valve in the feed hopper, which is provided in the two cylinder slurry pump as per the invention, leads to an adjustable movement of the slurry in addition to the agitator, as soon as the sleeve valve starts its controlling movements. 
     Such two cylinder slurry pumps are already known as concrete pumps (DE-AS 23 15 857). The arrangement of the paddle to the end of the agitator shaft is right next to the side wall of the feed hopper. The openings of the cylinder are located between the dividing circles which are made by the externally arranged paddles during the rotation of the agitator shaft. The inlet arm of the agitator is arranged in the feed hopper in front of the cylinder openings. With a two cylinder slurry pump of this construction the paddle can not immediately feed the slurry to the cylinder openings in order to rule out the intake of air in the feed cylinder during the suction cycle because the backwards and forwards moving inlet arm of the agitator in front of the cylinder openings takes up the middle area between the two paddles on the agitator shaft. That is why the desired dispersing effect of the paddles in the middle area of the feed hopper in front the cylinder opening does not take place. It can therefore occur during operation that the slurry thickens in this middle area and, with concrete for example, a bridge can form which obstructs the suction of the cement in the cylinder or can even prevent it. In doing so, the feeding performance, especially when pumping concrete, is considerably reduced at the least. 
     The invention works differently. Its fundamental idea is described in claim  1 . Further characteristics of the invention are the subject matter of the subclaims. 
     In accordance with the invention, the openings of the feed cylinder have been positioned out of the feed hopper and towards the back. In this way the sleeve valve is able to move towards the back. As per the invention, this takes place to such an extent that the outlet arm of the sleeve valve can be arranged behind the agitator shaft on the rear wall. 
     With this functioning arrangement of the agitator shaft, e.g. in the centre of the feed hopper, the invention enables the paddle trim of the shaft to be driven up to around the length of the feed hopper. This results in a breaking up of the slurry directly in front of the cylinder openings whilst avoiding the bridge formation and also a stirring effect across the entire width of the feed hopper. 
     In accordance with a preferred embodiment of the invention, which is the subject matter of the claim  2 , the sleeve valve has an L-shape which means that the inlet and outlet arm unit realises a 90° pipe bend. As the inlet arm is not limited in its length, one can, with such a shaped sleeve valve, recess the openings of the feed cylinder sufficiently enough and arrange the outlet arm of the sleeve valve between the agitator and the rear wall. In doing so, the mounts of the sleeve valve are arranged is such a way that they have a comparatively short contact travel. 
     A further development of this embodiment, in accordance with claim  3 , is especially the L-shape of the sleeve valve, as described above, which enables the sleeve valve to tip backwards so that the axle centre of the outlet arm is tilted vertically in the direction towards the rear wall of the feed hopper, whereby the angle of inclination is an advantageous 30°. This way the cylinder openings lie deeper than the floor of the feed hopper. In doing so it is possible to keep the residue concrete in the feed hopper low after the slurry has been fed, as the agitator feeds the concrete to the middle of the feed hopper and as a result the inlet arm of the sleeve valve tilts downwards. The advantage of such a two cylinder slurry pump lies also in the fact that after the shut-down it is possible to feed no longer feedable slurry amounts, irrespective of the feed volume of the feed hopper. Therefore, when one realises the invention, one can easily increase the level of the feed material to such an extent by way of an adequate enlargement of the feed hopper, so that no suction craters can form, which can arise from the air in the feed cylinder, when accepting the slurry in the feed hopper, even at a high suction speed. Loss of slurry and disposal difficulties when clearing up the no longer feedable slurry residue from the feed hopper is therefore much decreased. 
     With the embodiment of the invention described up until now one mainly realises also the characteristics of claim  4 , whereupon among other things the pivot bearing of the sleeve valve, which enables its control movements, is arranged on the outside of the rear wall of the feed hopper. This way it is possible, in contrast to the latest developments in technology, to make the upper opening of the feed hopper totally free and, with the given dimensions of the feed hopper, it is possible to reduce the limitation of the filler opening through the sleeve valve to a minimum and with L-shaped sleeve valves this mainly takes place by means of the outlet arm. 
     With the characteristics of claim  5  the cylinder openings are established in an attached channel-shaped housing which is a closed unit apart from an opening in the feed hopper. The channel shape encloses the inlet arm of the sleeve valve and ensures that the slurry displacement caused by the swinging of the inlet arm of the sleeve point remains low. This is desirable because the tail wave occurring during the swinging of the sleeve valve to the back of the inlet arm does no longer cause a hollow space therefore improving the filling of the suction cylinder. In addition, the drive forces of the sleeve point are decreased which is also of a considerable advantage. 
    
    
     The details, further characteristics and other advantages of the invention can be seen in the following description of an example using the figures in the illustrations. It shows 
     FIG. 1 a sectional partial view of a concrete pump in accordance with the invention, 
     FIG. 2 a similar sectional top view of the subject matter of FIG. 1, with a sectional cut lengthways along the line II—II of the FIG.  1  and 
     FIG. 3 a partial view with a sectional cut lengthways along the line III—III of FIG.  2 . 
    
    
     The slurry pump, which is generally referred to as  1 , in accordance with the execution example shows a feed hopper  2  in which the concrete, for example, to be fed from the mixer is fed across a slide. The feed hopper has a rectangular opening  3 , the parallel long sides of which form a front wall  4  and a rear wall  5 . The plans of the side walls  6  and  7  illustrate a lower bend  8  and a divergent arm  9  and  10 . Thus resulting in an upper open trough shape of the feed hopper  2 . 
     An agitator shaft  11  pushes through the approx. centre of the feed hopper  2 . This is equipped with the agitator tools which are mounted to the shaft and set against one another as well as arranged at intervals from one another in the longitudinal direction of the shaft. The agitator tools  12  to  14  are arranged symmetrically to the longitudinal surfaces of the feed hopper  3  and extend, with ascending ordinal number, up to the outlet arm  15  of a sleeve valve with is generally identified referred to as  16 , the other arm of which serves as an inlet arm for the concrete and has an angle of approximately 90° to the outlet arm  15 . This results in an L-shaped arrangement of the sleeve valve, which swings in the sleeve pivot joint  18  around the shaft of the rising outlet arm  15 , whereby the sleeve pivot joint  18  is connected to the end of a pressure pipe  19 . A pivot bearing  20  supports the sleeve valve  16  on a crossbeam  21  which is mounted at both ends at  22  and  23  by rising supports. 
     A channel-shaped housing  24  is flanged with its internal opening  25  at  26  to the floor of the hopper. The housing  24  has a curve-shaped rear wall  27 , the curve of which corresponds to the swinging motion of the inlet arm. On the inside of the curve-shaped wall  27  sits a cartridge plate  28  while a cut ring  29  forms the end (which can wear and tear) of the inlet arm  17  and is pressed with a rubber-elastic seal  30  against the cartridge plate  28 . 
     A connecting housing  31 , which is linked on both sides to the rising supports  32  and  33 , forms the connection to the feed cylinders  34  and  35 . 
     The cartridge plate encloses both openings  45  and  46 , through which the feed cylinder  34 ,  35  suck and feed concrete through the sleeve valve  16  into the pressure pipe  19 . These openings form the respective internal ends of two tubular supports  38  and  39  which are curved outwards from the curve-shaped rear wall  27  of the channel housing  24 , in order to bridge the construction-determined lateral distance of the two feed cylinders  34  and  35  with their pistons  36  and  37 . 
     The L-shaped unit from the inlet arm  17  and the outlet arm  15  as well as the 90° inclination of the sleeve valve  16  is inclined by around 30° backwards in the direction of the rear wall  5  of the feed hopper  2  and the feed cylinders  34  and  35  lying behind it. Due to this, the inlet arm  17  and the channel housing  24 , which encloses it protrudes downwards. Below the opening of the channel housing in the feed hopper  2  is a tip chute  47  on which the concrete is transported in front of the feed cylinder openings  45  and  46 . 
     The sleeve valve  16  swings in the cycle of the counter-rotating pistons  36  and  37  in front of the feed cylinder openings of the respective suction pistons  37  around the longitudinal axis of the outlet arm  15  in the bearing  20  and the sleeve pivot link  18  of the pressure pipe  19 . The sleeve valve is additionally supported with pins  48  to its lower drive shaft  40  on the floor of the tip chute  47 . A lower drive  41  or a higher drive  42  transmits the kinetic energy for the sleeve valve to the shaft  40  or the upper end of the outlet arm  15  between the bearing  20  and the sleeve pivot joint  18 . 
     Depending on the construction, the feed cylinders  34 ,  35  are inclined vertically upwards. The connection between the inclination of the tip chute  47  and the channel housing  24  with the feed cylinder ends produces the connecting housing  31  which has the pipe bends  49 ,  50  and is connected with  43  and  44  to the channel housing  24 . 
     During operation, the concrete is shovelled with the aid of angled driving paddles  12  to  14  of the agitator from both sides of the feed hopper  2  to the middle and reaches the tip chute  47  in front of the cylinder openings  45  and  46  of the respective suction feed cylinders  34  and  35 . This provides a hydrostatic concrete pressure in front of the respective suction openings which exceed the height of the floor  8  of the feed hopper  2 , whereby the agitator ensures that sufficient concrete is always available in order to avoid the formation of suction craters in front of the openings  45  and  46 . At the end of the feed operation, the feed hopper will be practically empty as no residue concrete remains in the feed hopper  2  by way of the effects of the paddles. 
     REFERENCE SIGN LIST 
       1  Slurry pump 
       2  Feed hopper 
       3  Opening 
       4  Front wall 
       5  Rear wall 
       6  Side wall 
       7  Side wall 
       8  Floor 
       9  Arm 
       10  Arm 
       11  Agitator shaft 
       12  Agitator tools 
       13  Agitator tools 
       14  Agitator tools 
       15  Outlet arm 
       16  Sleeve valve 
       17  Inlet arm 
       18  Sleeve pivot joint 
       19  Pressure pipe 
       20  Pivot bearing 
       21  Crossbeam 
       22  Support 
       23  Support 
       24  Channel housing 
       25  Opening 
       26  Flange 
       27  Curve-shaped rear wall 
       28  Cartridge plate 
       29  Cut ring 
       30  Seal 
       31  Connecting housing 
       32  Rising support 
       33  Rising support 
       34  Feed cylinder 
       35  Feed cylinder 
       36  Piston 
       37  Piston 
       38  Tubular support 
       39  Tubular support 
       40  Drive shaft 
       41  Swing drive 
       42  Swing drive 
       43  Flange 
       44  Flange 
       45  Feed cylinder opening 
       46  Feed cylinder opening 
       47  Tip chute 
       48  Pins 
       49  Pipe bend 
       50  Pipe bend