Liquid pump

Description

The invention relates to a liquid pump according to the preamble to claim 1.

Liquid pumps, in particular for household machines, dishwashers, washers or the like, are already commercially available in so-called wet-running models. The rotor of the motor is here incorporated in a rotor chamber, the casing wall of which separates the stator from the rotor in a liquid-tight manner. The rotor chamber is here connected relative to the pump chamber inside the pump casing in such a way as to allow liquid through, so that an exchange of liquid or water takes place. The casing of the rotor chamber is often also referred to as a slit tube, since it extends through the annular gap between the rotor and stator.

The design of a wet runner leads to a higher efficiency in this application, since the liquid or water is utilized to cool the motor, so that the exhaust heat of the motor is used to warm the liquid or water. A corresponding amount of energy can be saved during subsequent heating processes.

In addition, this design offers a good insulation for the stator, yielding advantages relating to the production and assembly of the stator, and of the electrical connections.

However, the disadvantage to conventional wet runners is that the liquid-exposed connection of the rotor chamber to the pump chamber can contaminate the rotor chamber. In addition, the rotor chamber along with the pump chamber is evacuated when not in operation.

By contrast, the object of the invention is to propose a liquid pump that avoids or at least diminishes the disadvantages mentioned above while retaining the advantages to a wet runner.

This object is achieved based on a liquid pump of the kind mentioned at the outset by the characterizing features in claim 1.

The measures specified in the subclaims enable advantageous embodiments and further developments of the invention.

Consequently, one liquid pump according to the invention is characterized in that a thermally conductive separating wall is provided between the pump chamber and rotor chamber.

This measure enables embodiments in which the transfer of liquid, and hence dirt, from the pump chamber into the rotor chamber is reduced, or even entirely prevented in extreme cases, while retaining the cooling function and exhaust heat utilization.

In the further development last mentioned, an at least temporarily liquid-tight separating wall is provided between the pump chamber and rotor chamber. This separating wall completely decouples the rotor chamber from the pump chamber, and hence from the circulating liquid, during pump operation, at least in the closed time intervals. This completely precludes any contamination by the circulating liquid with respect to the rotor chamber. The thermally conductive design of the separating wall ensures that the advantages of the wet runner are retained, i.e., good motor cooling and exhaust heat utilization.

To improve the transport of heat from the rotor chamber into the pump chamber, a surface-enlarging structure is preferably provided for the separating wall. Such a surface-enlarging structure can be realized, for example, via appropriate shaping, i.e., in the form of grooves, zigzag profiles or the like. It would also be conceivable to introduce ribs or the like in the transitional area between the rotor chamber and pump chamber.

In a preferred embodiment, however, only the cross section of the rotor chamber is expanded in the area of transition to the pump chamber, thereby enlarging the surface of the separating wall to the pump chamber. In comparison to the aforementioned embodiments with surface-enlarging structures in the pump chamber, this embodiment better facilitates flow, and can also be manufactured more easily, and hence less expensively.

In order to utilize the advantages of a wet runner, the rotor chamber must be filled, at least during startup. This can take place during pump assembly, for example.

However, in a particularly advantageous embodiment of the invention, the rotor chamber is first filled when starting up the pump. To this end, the separating wall is preferably provided with a passage through which this filling takes place.

In addition, if air unexpectedly gets into the area of the rotor chamber, a corresponding passage can be used in a further development of this embodiment for renewed filling with liquid or water.

In a further development of this embodiment, the rotor chamber is provided with a valve to enable filling of the rotor chamber while providing a liquid-tight seal between the rotor chamber and pump chamber during operation. Such a valve can be used to open a passage for filling purposes, and again close it during operation.

It is also advantageous to provide the rotor chamber with a vent valve to facilitate filling, e.g., during initial startup or given an undesired evacuation of the rotor chamber. In a special embodiment, such a vent valve can interact with a correspondingly small and suitably arranged open fill hole in such a way that liquid is only resupplied during the simultaneous removal of air through the vent valve.

In an advantageous embodiment, the fill valve for the rotor chamber is designed as a floater, thereby enabling an automatic evacuation and refilling of the rotor chamber via the pump circulation.

An advantageous further development provides for the controlled filling of the rotor chamber with liquid, e.g., water, via the pump circulation. This control can be implemented as a function of various parameters. In this case, control can take place via an independent valve or an actuated valve, for example. The valve can here be designed for electromagnetic, mechanical or even hydraulic actuation, for example.

In a special embodiment of the invention, rotor chamber filling is actuated as a function of the presence of air in the rotor chamber. Among other ways, this can take place, for example, by way of an automatic vent valve in conjunction with a float valve, for example, in the separating wall between the rotor chamber and pump chamber without external actuation. However, controlled, air-dependent refilling by means of an air sensor, e.g., a floater, a light barrier or the like, is also conceivable.

It is further conceivable that the rotor chamber be filled as a function of temperature. In this case, it would be possible to use a valve, e.g., comprising a thermostat, thereby permitting liquid to pass into the rotor chamber if a threshold temperature has been exceeded. As a consequence, if the rotor chamber is evacuated, e.g., as the result of leaks, so that sufficient cooling is no longer ensured, the temperature increases accordingly in that location until a filling with liquid takes place via the pump circulation. Such a temperature-dependent filling would also be conceivable in another embodiment with a temperature sensor and an external actuation of a corresponding fill valve.

In another embodiment of the invention, the rotor chamber is filled depending on the rotational direction of the drive motor.

In this case, the axial force exerted by a corresponding pump wheel on the axis could be used to open or close a passage between the pump chamber and the rotor chamber. The rotor chamber would here be filled by briefly running the motor in a rotational direction opposite the normal operating state. To this end, a corresponding motor controller could be provided to initiate rotor chamber filling as a function of corresponding state parameters. The axial force can be generated via a corresponding angular adjustment of the impeller blades, for example.

The rotor chamber can also be filled as a function of time, i.e., the passage between the rotor chamber and pump chamber can be opened at specific time intervals to ensure that the rotor chamber is always filled with enough liquid.

The key factor in terms of the invention when contrasted with conventional wet runner pumps is that the necessary thermal transport between the rotor chamber and pump chamber is initiated at least partially via the thermally conductive function of the separating wall, thereby diminishing, or even entirely avoiding, the liquid exchange between the pump chamber and rotor chamber.

One exemplary embodiment of the invention is shown in the drawing, and will be explained in greater detail below based on the figures.

• Shown specifically on:

FIG. 1 is a diagrammatic section through a liquid pump according to the invention with thermally conductive separating wall;

FIG. 2 is a diagrammatic section through a second liquid pump according to the invention with ventilation;

FIG. 3 is a diagrammatic section through a third liquid pump according to the invention with a rinsing system that operates as a function of rotational direction, and

FIG. 4 is a diagrammatic section through a fourth liquid pump according to the invention with a second rinsing device that operates as a function of rotational direction.

FIG. 1 diagrammatically depicts a liquid pump or so-called “wet runner” for a dishwashing machine with an inlet 10 and an outlet 11. The wet runner has a pump casing 1, which incorporates a pump chamber 2 with an impeller 3, and a motor 4 with a rotor 5 and a stator 6. The stator 6 is separated from a rotor chamber 8 by means of a wall 7.

A thermally conductive separating wall 9, in particular a metal wall 9, is provided between the pump chamber 2 and the rotor chamber 8. This separating wall 9 makes it possible to divert heat of the rotor chamber 8 or a fluid provided therein, in particular cooling liquid, into the pump chamber 2 or a pump fluid, in particular water, in an advantageous manner. A cooling system for the motor 4 according to the invention is thereby realized without potentially contaminated pump fluid or washing water being able to get into the rotor chamber 8.

In general, the components labeled with the same reference numbers in the figures are correspondingly comparable.

FIG. 2 shows a variant with a floater 12 for ventilating the rotor chamber 8. For example, the outlet 11 is situated above viewed in an axial direction. The floater 12 comprises a hole through which any gas present in the rotor chamber 8 can escape, in particular air. The separating wall 9 or the pump casing 1 can encompass the holes of the floater 12 in an advantageous manner.

FIG. 3 shows a variant that involves rinsing the rotor chamber 8 as a function of rotational direction. To this end, the separating wall 9 has at least one valve 13 with holes that can be opened or closed by means of a lever mechanism 14. For example, the mechanism 14 encompasses a spring.

The valve 13 is opened and closed when changing the rotational direction of the motor 4 by virtue of the fact that the impeller 3 generates an axially oriented force owing to an advantageous configuration of the blades. In turn, this force produces a relative movement 15 between the separating wall 9 and rotor 5, thereby changing the volume of the rotor chamber 8 or the pressure therein. As a result, the mechanism 13 opens and closes the holes in the separating wall 9. With the hole opened, the fluid of the rotor chamber 8 can be changed out in an advantageous manner.

The variant according to FIG. 4 also exhibits a rinsing system that operates as a function of rotational direction. However, the separating wall 9 here exhibits at least one comparatively large hole 16, which can be opened and closed by means of a paddle 17 or the like.

Depending on the rotational direction of the rotor 5, the paddle 17 is moved into a first or second position based on the flow of fluid present in the rotor chamber 8. FIG. 4b diagrammatically depicts a cutout section in the area of paddle 17. The hole 16 is open in the first position (solid line). The paddle 17 covers the hole 16 in the second position (hatched line). With the motor 4 turned off, the paddle rests along the central line 18.

The variants of the invention specified above can basically be combined as desired.

Reference List:

• • 1 Pump casing
  • 2 Pump chamber
  • 3 Impeller
  • 4 Motor
  • 5 Rotor
  • 6 Stator
  • 7 Wall
  • 8 Rotor chamber
  • 9 Separating wall
  • 10 Inlet
  • 11 Outlet
  • 12 Floater
  • 13 Valve
  • 14 Mechanism
  • 15 Movement
  • 16 Hole
  • 17 Paddle
  • 18 Line