Pumps – Expansible chamber type – Mechanically actuated distributor
Reexamination Certificate
1999-12-10
2001-03-27
Walberg, Teresa (Department: 3742)
Pumps
Expansible chamber type
Mechanically actuated distributor
Reexamination Certificate
active
06206662
ABSTRACT:
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'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 b
Fastovsky Leonid
Kinney & Lange , P.A.
Schwing GmbH
Walberg Teresa
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