JP2008509335A - Eccentric screw pump with integrated drive - Google Patents

Abstract

The pump has a rotor (1) which runs in it and a driving motor which is connected to the rotor such as a fixed winding (4). Runners surround the rotor and housing covers the runners. As the rotors are turned the fixed winding is arranged and the runner and the rotor are rigidly connected. A second runner (3a) is arranged near the cylindrical runners at the opposite end of the rotor and rotates on a circular path within a cylindrical housing (5a), at which the second fixed winding (4a) is arranged.

Description

  The present invention relates to a screw pump or an eccentric screw pump, and more particularly to a pump used for transferring a medium having a high viscosity or a solid mixed therein.

  An eccentric screw pump belonging to the technical field usually has a fixed external stator and a rotor operating within the fixed external stator. The rotor is typically driven by an external electric motor connected to the rotor by a cardan shaft or a flexible shaft. In the following description, no distinction is made between screw pumps and eccentric screw pumps, since they do not have any influence on the principle forming the basis of the present invention.

  However, known eccentric screw pumps have a long overall shape and require maintenance due to the numerous moving parts of the motor, cardan shaft and pump. Furthermore, such a configuration requires a seal against the cardan shaft on at least one side of the pump.

  In the configuration described in German Patent Application No. 10251844 (Patent Document 1), an important improvement is made in this regard. In this configuration, the rotor of the eccentric screw pump is also a member of the motor. Therefore, especially the cardan shaft can be omitted. Such a configuration has the disadvantage that only special rotors with expensive magnetic materials can be used. Furthermore, since the stator has a helical configuration, the stator windings are relatively complex, resulting in a relatively high production cost.

  German patent application DE 43 13 442 (Patent Document 2) describes another approach to the solution. For example, as shown in FIG. 24, an eccentric screw pump having a resilient stator and rotor driven by an electromagnetic coupling is provided. In this configuration, the movement of the screw is compensated by the elastic stator, so that the electromagnetic coupling can be mounted by using a simple bearing. These pumps are not suitable for high pressure because the jacketless stator has high elasticity.

  European Patent No. 0357317 (Patent Document 3) discloses a motor that simultaneously performs rotational movement and up-and-down movement in conjunction with an eccentric screw pump. Again, a resilient stator without a jacket is used to compensate for the eccentric movement of the screw. Therefore, this pump is not suitable for high pressure.

German patent application 102518446 German Patent Application No. 4313442 European Patent No. 0357317

  The object of the present invention is that the torque required to drive the pump is supplied independently of the additional means extending over the entire shape of the pump, and the shaft seal and shaft bearing, and is also suitable for high pressures. It is to constitute an eccentric screw pump.

  A solution to the problem of the invention is given in the independent claim 1. Further developments of the invention are indicated in the dependent claims.

  The device according to the invention comprises an eccentric screw pump comprising a stator 2 and a rotor 1 moving inside. In order to drive the rotor 1, a motor 1 is provided and connected to the rotor. The drive motor includes an armature 3 and a stator winding 4. The armature is formed as a substantially cylindrical armature and is firmly connected to the rotor so as to rotate on an eccentric track inside the substantially cylindrical pot 5. The pot 5 is at least partially surrounded by the stator winding 4. Alternatively, the stator windings can be incorporated into this pot. With such a configuration, the drive and pump are integrated into a single unit in a very space-saving manner. At the same time, the mechanical construction is greatly simplified. Thus, a fragile cardan shaft is not required because the rotor operates in a state of being completely closed inside the system comprising the stator and the connecting line. No connection or contact from the rotor to points outside the system is required. Thus, pumps including rotors and stators are flanged to existing pipes without the use of additional connections and shaft seals.

  With the arrangement according to the invention, it is also possible to dispense with a conversion member, such as a cardan shaft or a flexible shaft, for converting the circular motion of the drive motor into the eccentric motion of the rotor.

  In a particularly advantageous embodiment of the invention, the second armature 3a is provided as a substantially cylindrical armature. This armature is disposed at the end of the rotor opposite to the first armature. This armature is firmly connected to the rotor and therefore rotates on an eccentric track in the pot 5 as well. This second pot is similarly wrapped around the second stator winding or houses the second stator winding.

  In a further advantageous embodiment of the invention, the motor comprising the armature 3 and the stator winding 4 is realized in the form of a reluctance motor. For this purpose, the stator winding has a coil that generates a rotating magnetic field. The armature is provided with a preferably tooth-shaped member made of a magnetic or weak magnetic material such as iron. In this case, the teeth are aligned according to the magnetic field. Therefore, the rotation of the rotor can be realized by the rotation of the magnetic field.

  A control unit for controlling the corresponding member of the stator winding 4 is provided. In this case, the control unit controls the current flowing in the stator in order to generate torque, so that the magnetic flux preferably passes through the region of the pot 5 that has the shortest distance from the surface of the armature 3.

  Preferably, a position sensor is provided to indicate the exact position of the rotor or armature relative to the stator in order to properly control the coil. Such a position sensor can be realized by, for example, a magnet incorporated in the rotor.

  In a further advantageous embodiment of the invention, the motor is designed in the form of an asynchronous motor. For this purpose, the armature is realized as a resistance armature or preferably a short-circuit armature. Further, a winding for generating a rotating magnetic field is provided in the stator winding. The rotating magnetic field induces a voltage in the rotor winding or conductive rotor structure that generates an appropriate current depending on the electrical resistance of the winding or conductive rotor structure. These currents in turn generate a magnetic field and thus torque. For the control of the winding, an optional control circuit, preferably a frequency inverter, is provided for generating a phase-shifted signal of variable frequency that generates a rotating magnetic field with the desired rotation period.

  Optionally, a groove can be provided in the rotor to accommodate the rotor winding.

  In a different embodiment of the invention, the armature 3 is preferably provided with an axial perforation through which the medium can pass. A shunt for the medium is therefore no longer necessary. Therefore, a particularly small and space-saving structure can be obtained.

  In another advantageous embodiment of the invention, the magnetic parts or permanent magnets are arranged in the armature and the coils in the stator so that a predetermined force acts on the rotor in the axial direction. It is particularly advantageous if the axial force acts at the same strength and in the opposite direction to the pump pressure. In order to monitor the rotor position, it is preferable to use a position control device that controls the position of the rotor by means of at least one position sensor.

  In another embodiment of the present invention, a rotor is provided that is slidable in the axial direction by an axial force. With such mobility, the starting torque at the start of the pump can be reduced. This likewise allows the pump outlet to be closed, for example by the rotor itself. Alternatively, the valve element can be automatically actuated by the axial movement of the rotor. Especially in the case of metering pumps, this makes it possible to measure particularly finely without causing an excess.

  In a further advantageous embodiment of the invention, the armature coil has the opposite polarity to the coil transmitting torque to the rotor. Such controllable reverse polarity creates a force on the rotor that acts in a direction opposite to the direction of the flow of the pumped medium, thereby compensating or mitigating the hydrodynamic force generated by the medium on the front side of the rotor. . The required number of reverse polarity coils can be variably adapted to the resulting transfer pressure.

  The invention will be described below with reference to exemplary embodiments in conjunction with the drawings, which do not limit the general technical idea of the invention.

  FIG. 1 is a cross-sectional view of a device according to the invention cut perpendicular to the axis of rotation. The eccentric screw pump has a rotor 1 that moves inside a stator 2. The rotor 1 is firmly connected to the armature 3. The armature rotates on an eccentric track inside the pot 5. In this case, the medium to be transferred passes through the pot 5. In order to generate torque, at least one stator winding 4 is provided. In the illustrated embodiment, the stator windings can also be incorporated into the pot or suitably placed outside the pot and thus outside the medium. However, the stator winding can optionally be incorporated into the pot and sealed, for example. The stator winding comprises individual coils. These coils can be optionally supplied with current by a control device.

  Preferably, a position sensor is provided to indicate the exact position of the rotor or armature relative to the stator or pot in order to properly control the coil. Such a position sensor can be realized by a magnet incorporated in the rotor or its assistance.

  FIG. 2 is a perspective view of the above configuration.

  FIG. 3 shows another device of the present invention comprising a second armature. The second armature is disposed at the end of the rotor opposite to the first armature. Similarly, in order to generate torque, the second pot 5a and the second stator winding 4a are assigned to the second armature. In such a configuration, it is advantageous to form the armatures so that both armatures generate axial thrust forces directed toward each other that hold them and the rotor in place. For this reason, the armature can be advantageously formed to be at least slightly tapered.

  FIG. 4 is a perspective view of the above configuration.

It is sectional drawing which shows the whole shape of the apparatus by this invention. It is a perspective view which shows the whole shape of the apparatus by this invention. And FIG. 6 is a cross-sectional view of a device according to the invention with a second armature. FIG. 6 is a perspective view of a device according to the invention with a second armature.

Explanation of symbols

1 Rotor 2 Stator 3 Armature 4 Winding 5 Pot

Claims (12)

  A stator (2), a rotor (1) moving inside the stator, and a drive motor for driving the rotor, the drive motor being connected to the rotor (1), comprising a stator winding (4) and an armature (3, 3a) The armature is formed as a substantially cylindrical armature and rotates on an eccentric track inside the substantially cylindrical pot (5), in which the stator winding (4) is arranged, and the armature and An eccentric screw pump characterized in that the rotor is firmly connected.   The second armature is arranged as a substantially cylindrical armature (3a) at the end of the rotor (1) opposite to the first armature, and is eccentric in the substantially cylindrical pot (5a). The eccentric screw pump according to claim 1, wherein the second stator winding (4a) is arranged in the pot and rotates on the track.   An eccentric screw pump according to claim 1 or 2, characterized in that a plurality of rotors (1) each having a driven armature are arranged in a series of armatures and rotors.   The eccentric screw pump according to any one of claims 1 to 3, wherein a permanent magnet, a reluctance magnet or a soft magnetic material is provided inside the armature (3).   A control unit is provided for controlling the corresponding member of the stator winding (4) according to the position of the armature (3) so that torque acts on the rotor, and the magnetic flux is preferably in the pot (5). The eccentric screw pump according to any one of claims 1 to 4, characterized in that it passes through a region having the shortest distance from the surface of the armature (3).   The eccentric screw pump according to any one of claims 1 to 5, characterized in that the armature (3) has perforations and the medium can pass through the perforations.   7. A permanent magnet and further a coil (4) are arranged in the armature (3) so that a predetermined axial force acts on the rotor (1). The eccentric screw pump according to item.   The permanent magnets or coils (4) are arranged in groups inside the armature (3), the axial force of each group acting on the rotor preferably in the opposite direction. The eccentric screw pump as described in any one.   The eccentric screw pump according to claim 7 or 8, wherein the rotor is slidable in an axial direction by an axial force.   The eccentric screw pump according to claim 7 or 8, wherein another axial force is applied or further operation is performed in order to reduce a starting torque at the start of the pump.   The eccentric screw pump according to claim 7 or 8, characterized in that further axial movement is used to close the pump outlet or actuate the valve body.   The eccentric screw pump according to any one of claims 1 to 11, characterized in that a further axial movement is used to close the pump outlet or actuate the valve body.

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