BACKGROUND

The invention relates to a thick material pump having a first delivery cylinder, a second delivery cylinder and an additional cylinder. The additional cylinder is configured to bridge a delivery gap between the first delivery cylinder and the second delivery cylinder. The delivery pump comprises a movable tube section which, in a first state, forms a connection between the first delivery cylinder and an outlet of the thick material pump and which, in a second state, forms a connection between the second delivery cylinder and the outlet of the thick material pump.

Such pumps serve to deliver thick materials, such as for example fresh concrete or mortar. The delivery cylinders suck the thick material out of a reservoir with a rearward movement. The thick material is delivered in the direction of an outlet of the thick material pump with a forward movement.

The delivery cylinders are alternately connected to the outlet of the thick material pump with the movable tube section. The respective other delivery cylinder is not connected to the outlet in this phase but rather can suck in thick material from the reservoir with the rearward movement.

If the forward movement of the first delivery cylinder is ended, the movable tube section is switched over to the second delivery cylinder. During the transition from the first delivery cylinder to the second delivery cylinder there is an interruption in the flow of material owing to the changing between the delivery cycles of the delivery cylinders.

By means of the additional cylinder, the transition between the two delivery cylinders is bridged in that the additional cylinder delivers thick material in the direction of the pump outlet during the switching over of the tube section. It therefore becomes possible to generate an essentially continuous flow of material in the direction of the pump outlet, DE 42 08 754 A1, U.S. Pat. No. 3,963,385. In this context, a backflow of the material delivered by the additional cylinder can occur into one of the delivery cylinders.

SUMMARY OF THE INVENTION

In the invention, the object is based on presenting a thick material pump with which a uniform flow of material can be generated in the direction of the pump outlet. Taking the abovementioned prior art as a basis, the object is achieved with the features of claim1. Advantageous embodiments are specified in the dependent claims.

According to the invention, the movable tube section comprises a switchable closure which is arranged between an inlet end of the movable tube section and the additional cylinder.

Since a switchable closure is integrated into the movable tube section, the distance from the additional cylinder to the delivery cylinders can be closed when the additional cylinder delivers thick material. This can prevent a backflow from the additional cylinder in the direction of the delivery cylinders.

The movable tube section can extend from the inlet end to an outlet end. The specifications inlet and outlet relate to the direction of movement of the flow of material which is set in train with the forward movement of a delivery cylinder. The movable tube section can be rigid, with the result that the inlet end or the outlet end have a fixed spatial relationship with respect to one another. Embodiments in which the tube section is movable in itself, that is to say in which the position of the inlet end can be moved relative to the position in the outlet end, are also possible.

The tube section can be mounted so as to be movable relative to a supporting structure of the thick material pump. The bearing arrangement can comprise a rotary bearing around which the tube section can be rotated. The rotary bearing can be oriented concentrically with respect to an outlet end of the tube section. An end face of the tube section which forms the outlet end can be oriented perpendicularly with respect to the rotational axis. As a result, the tube section can be coupled independently of its rotational position to a connecting tube which is arranged in a fixed position.

The inlet end of the tube section can be arranged offset in the radial direction with respect to the axis of the rotary bearing. The inlet end of the tube section then changes position when the tube section is rotated. During the subsequent arrangement of the delivery cylinders, the inlet end can optionally be coupled to the first delivery cylinder or to the second delivery cylinder by rotational movement of the tube section. An end face of the tube section which forms the inlet end can be oriented perpendicularly with respect to the rotational axis.

The tube section can comprise a branch which leads off to the additional cylinder, with the result that the additional cylinder is accessible from the interior of the tube section. It is therefore possible to offset or keep moving the flow of material of the thick material in the tube section with a forward movement of the additional cylinder. Since the branch is arranged in the movable tube section, there are short distances between the delivery cylinders, the additional cylinder and the switchable closure, which is advantageous for generating a continuous flow of material.

Thick material is a generic term for media which are difficult to deliver. Thick material may be, for example, a material with coarsely grained components, a material with aggressive components or the like. The thick material can also be a bulk material. In one embodiment, the thick material is fresh concrete. Fresh concrete can contain grains up to a size of more than 30 mm, hardens, forms deposits in dead spaces and is difficult to deliver for these reasons.

Since the switchable closure is a component of the movable tube section, the movable tube section can be switched over without the switched position of the closure being changed. In particular, the tube section can comprise a first partial section which extends between the inlet end and the closure, and a second partial section which extends between the closure and the branch. The closure can be switchable, with the result that in a first state it permits the flow of material to pass through from the delivery cylinder in the direction of the outlet end of the tube section, and so that in a second state it prevents a backflow of material from the branch in the direction of the inlet end.

The closure can comprise a gate valve, which in a first position clears the cross section of the tube, and in a second position closes off the tube. The gate valve can be mounted so as to be rotatable with respect to a pivoting axis, with the result that it can change between the two positions by rotating about the pivoting axis. It can be advantageous for simple activation of the gate valve if the pivoting axis of the valve coincides with the rotational axis of the tube section. Other mechanisms for moving the valves are also possible. For example, the gate valve can be moved in a translatory fashion in order to change between the two positions. Combinations of rotary and translatory movements are also possible. In all cases, the movement can take place in the plane of the gate valve.

The invention includes embodiments in which the additional cylinder is fixedly connected to the movable tube section. In such embodiments, the additional cylinder also moves when the tube section is moved. In order to keep the moved masses low, it can be advantageous if the additional cylinder is connected to the supporting structure of the thick material pump, with the result that the tube section can be moved independently of the additional cylinder.

The thick material pump according to the invention can be configured in such a way that the connection between the interior of the tube section and the additional cylinder continues to be maintained in any rotational position which the tube section assumes during operation of the pump. Thick material can then be fed in the direction of the outlet end of the pump with the additional cylinder independently of the rotational position of the tube section. In particular, the tube section can have an opening which is coaxial with respect to the rotational axis of the tube section and which is adjoined by the additional cylinder.

The movable tube section can form a linear path which extends from an opening facing the additional cylinder as far as the outlet end of the tube section. The linear path can extend parallel to the rotational axis of the tube section and can be, in particular, coaxial with respect to the rotational axis. The coaxial arrangement has the advantage that the forces acting on the tube section are low while the tube section is rotated about the rotational axis and while the additional cylinder feeds material through the tube section.

The path which starts at the inlet end can enclose, with the branch leading to the additional cylinder, an angle which is less than 90°, preferably less than 60°, and more preferably less than 45°. Such an acute angle has the advantage that the flows of material coming from the additional cylinder and the delivery cylinders can be combined well to form a common flow of material.

The thick material pump according to the invention can be configured in such a way that the two delivery cylinders are activated in opposing directions. This means that the forward movement of a piston which is arranged in the one delivery cylinder takes place at the same time as the rearward movement of a piston which is arranged in the other delivery cylinder. In particular, the opposing movements can be synchronized. The forward movement of the one delivery cylinder can start at the same time at which the rearward movement of the other delivery cylinder starts. The forward movement of the one delivery cylinder can end at the same time at which the rearward movement of the other delivery cylinder ends. The absolute value of the speed can be the same at any time.

The activation of the delivery cylinders can be adjusted to the movement of the tube section. The tube section can therefore be connected to the first delivery cylinder when the forward movement of the first delivery cylinder takes place. The access to the second delivery cylinder can be free in this first state, with the result that the second delivery cylinder can suck in thick material from the reservoir with its rearward movement.

The tube section can be connected to the second delivery cylinder when the forward movement of the second of responder takes place. The access to the first delivery cylinder can be clear in the second state, with the result that with its rearward movement the first delivery cylinder can suck thick material out of the reservoir.

The closure with which a backflow from the additional cylinder in the direction of the delivery cylinder is prevented can also be adjusted to the delivery cylinders or to the tube section. In particular, the closure can be switched in such a way that it permits a free passage through the tube section if either the first delivery cylinder or the second delivery cylinder is in the forward movement.

The closure can close off the tube section between the inlet end and the branch while the tube section is switched over between the first delivery cylinder and the second delivery cylinder. It is possible to provide a time period during the switching over of the tube section, in which time period the piston of the first delivery cylinder and/or the piston of the second delivery cylinder are at rest. The time period can extend over the entire duration of the switching over process.

The delivery cylinder to which the tube section is coupled after the switching over can build up a pressure with an initial forward movement of the piston before the closure is switched over. As a result, it is possible to reduce the pressure difference which is present across the closure during the switching over.

The additional cylinder can be configured in such a way that it carries out a forward movement while the closure is in the closed state. In particular, the forward movement can extend over the entire time period in which the closure is in the closed state. The start of the forward movement of the additional cylinder can overlap with the end of the forward movement of a delivery cylinder. The end of the forward movement of the additional cylinder can overlap with the start of the forward movement of the other delivery cylinder. The additional cylinder and the delivery cylinders can be adjusted to one another in such a way that the sum of the required quantities of material is approximately the same over time. It is then possible to deliver a constant flow of material in the direction of the pump outlet. In particular, it is possible to reduce the speed of the forward movement, both at the additional cylinder and at the delivery cylinders if a further cylinder of the cylinder is carrying out the forward movement.

An active drive, for example in the form of a hydraulic drive, can be provided for the forward movement of the piston which is arranged in the additional cylinder. The rearward movement of the piston can also be carried out by the active drive. It is also possible for the piston to be moved back passively by the pressure of the material located in the tube section. The additional cylinder is then fed by a flow of material which is generated by the delivery cylinders. Both the forward movement and the rearward movement can be driven actively at the first delivery cylinder and at the second delivery cylinder. The drive can be, for example, a hydraulic drive.

The movable tube section can extend through a pre-filling container. During operation of the pump, the quantity of thick material which is equivalent to the quantity which can be fed in the direction of the pump outlet by the delivery cylinders can be subsequently filled into the pre-filling container. During the rearward movement, the delivery cylinders can be connected to the pre-filling container, with the result that they can suck in thick material from the pre-filling container.

In particular, the inlet end of the tube section can be arranged within the pre-filling container. The outlet end of the tube section can be arranged inside or outside the pre-filling container. The movable tube section can be mounted with two rotary bearings. The distance between the two rotary bearings can extend through the pre-filling container. The drive for the movement of the tube section and/or the drive for the movement of the closure can be arranged outside the pre-filling container. In particular, one of the drives can be arranged on the one side of the pre-filling container, and the other drive can be arranged on the other side of the pre-filling container.

The drive for the switchable closure can be supported on a structure of the thick material pump, with the result that the closure can be moved relative to the structure by the drive. This structure can be the supporting structure of the thick material pump. If the switched state of the closure remains unchanged during the switching over of the movable tube section, the drive of the switchable closure can be passively entrained during the movement of the tube section.

Alternatively, the drive for the switchable closure can be supported on the structure which forms part of the movable tube section. During the switching over process of the tube section, the switchable closure and its drive are then moved entirely, with the result that when the movable tube section is switched over the switched state of the closure and the state of the associated drive remain unchanged. This reduces the mechanical complexity, however more mass has to be moved when switching over the tube section.

The drive of the switchable closure can be configured in such a way that it is activated only when the movable tube section is at rest. It is also possible for the switching movements of the closure to be superimposed on the switching movement of the movable tube section.

The pre-filling container and the delivery cylinders can be connected to the supporting structure of the thick material pump, with the result that they are in a fixed spatial relationship with one another. The delivery cylinders can be oriented parallel to one another and be arranged at the same height. The orientation of the delivery cylinders can be parallel to the rotational axis of the tube section. The rotational axis of the tube section can be arranged centrally within the delivery cylinders and above the delivery cylinders. The additional cylinder can be arranged parallel to the delivery cylinders.

The thick material pump can comprise precisely two delivery cylinders. It is then switched over alternately from the first to the second delivery cylinder and from the second to the first delivery cylinder. If the thick material pump comprises more than two delivery cylinders, the movable tube section can be switched over cyclically between the delivery cylinders. In all cases, the additional cylinder can be configured in such a way that it bridges each of the transitions.

The term delivery cylinder is to be understood in a functional way. The invention also includes embodiments in which the two delivery cylinders are, according to the invention, combined in one physical cylinder, wherein either two pistons move in the same cylinder, or one piston carries out a forward movement according to the invention in both directions of movement. In one preferred embodiment, the pump comprises two cylinders which are physically separated from one another and which form the two delivery cylinders.

The movable tube section and the additional cylinder can be elements of one unit which is detachably connected to the thick material pump. This can facilitate the maintenance and cleaning of the thick material pump according to the invention.

The thick material pump can comprise an alternative operating mode in which only the two delivery cylinders are in operation, while the additional cylinder is not in operation. This operating mode can be an emergency mode.

