Peripheral impeller pump and water supply system of a caravan

Abstract

The invention relates to a peripheral impeller pump (2) comprising a drive motor (5), an impeller (16) which is coupled to the drive motor (5), and a separating wall (30) which is provided between the drive motor (5) and the impeller (16). The invention is characterized in that an elastic spring element (36) is provided which allows the impeller (16) to move away from the drive motor (5) for deflecting purposes. The invention also relates to a water supply system of a caravan, comprising a water circuit and such a peripheral impeller pump (2).

Description

[0001] Truma Gerätetechnik GmbH & Co. KG

[0002] Our reference: ? 15687 WO

[0003] St / St

[0004] Peripheral impeller pump and water supply system of a caravan. The invention relates to a peripheral impeller pump with a drive motor, an impeller coupled to the drive motor, and a partition arranged between the drive motor and the impeller. The drive motor is designed as an electric motor with a stator and a rotor, and the rotor is arranged in an annular space separated by the partition from a pump chamber in which the impeller is located. The partition allows the annular space to be flushed with water during operation of the peripheral impeller pump in order to dissipate some of the waste heat from the drive motor. The invention also relates to a water supply system of a caravan, comprising a water circuit and a peripheral impeller pump.

[0005] The peripheral impeller pump is used to pump water. In a preferred application, the peripheral impeller pump is part of a caravan's water supply system.

[0006] The caravan can be a motorized caravan (for example, a motorhome) or a non-motorized caravan (for example, a camper van). The water supply system serves to provide water to a user when needed, for example, at a sink. If the water supply system has a hot water circuit, hot water can also be provided, for example, for a shower.

[0007] One challenge with a water supply system in a caravan is that the water freezes when the caravan is not used or heated in winter and the ambient temperature drops below freezing. The increase in volume that occurs during this change of state from liquid to solid puts stress on all water-carrying components.

[0008] The increase in volume is particularly problematic for technically complex components of the water supply system. These components include the peripheral impeller pump, which is used to deliver water to a consumer.

[0009] There are known water pumps designed to automatically drain when not in use. Assuming this works reliably, the water pump is thus reliably frost-proof.

[0010] However, there are water pumps and water supply systems where it cannot be reliably guaranteed that the pump will automatically drain when not in use. This may be because the pump is not located at the highest point of the water supply system and therefore cannot drain completely. It may also be because the pump is designed in such a way that its internal components cannot drain.

[0011] Peripheral impeller pumps are particularly problematic, as the pumped water is also used to cool the pump's drive motor. The drive motor's rotor is located in an annular space, which is separated from the pump chamber by a partition wall. During operation, the impeller rotates within this pump chamber.

[0012] The impeller is mounted on a shaft that extends through the partition from the motor side to the pump side. The partition allows water to flow through the annular space.

[0013] The peripheral pump is usually mounted so that the drive motor is located above the impeller. If the peripheral pump cools below the freezing point of water, the water in the annular space freezes from top to bottom. Due to the increase in volume of the water upon freezing, the partition wall is pushed away from the drive motor. This exerts high forces on the impeller. These forces can damage the connection between the impeller and the shaft, or even the shaft itself.

[0014] The object of the invention is to create a peripheral impeller pump that ensures, with minimal effort, that no damage occurs when the pump is exposed to temperatures below the freezing point of water. To achieve this object, the invention provides an elastic spring element in a peripheral impeller pump of the type mentioned above, which allows the impeller to move away from the drive motor. The invention is based on the fundamental idea of ​​avoiding complex measures against freezing and instead enabling the impeller to yield in a mechanically simple manner when the partition wall is deformed.

[0015] The elastic spring element can be made of rubber or an elastomer, a material that is available in a wide variety of geometric shapes and hardnesses at low cost. Therefore, a desired spring behavior can be achieved with minimal effort.

[0016] The elastic spring element can also be made of a spring-elastic metal, i.e., a material that has a high spring deflection and a low dependence of the spring stiffness on temperature changes. The spring-elastic element can be designed as a coil spring or a wave spring.

[0017] The elastic spring element can be a ring that is compact and can be arranged concentrically with the axis of rotation of the pump impeller.

[0018] According to one embodiment, the impeller can be arranged on a shaft that is supported at least against axial movement away from the drive motor, with the elastic spring element allowing axial movement of the impeller relative to the shaft. In this embodiment, the shaft on which the impeller is mounted can be precisely installed and guided without the risk of damage if the partition presses on the impeller; the impeller can slide on the shaft against the action of the elastic spring element.

[0019] The elastic spring element can be positioned between a stop associated with the shaft and the pump impeller. This allows the elastic spring element to be designed as a compact ring that is compressed under axial loads between the pump impeller and the stop. Proven designs can be used for the stop, for example, by using a retaining ring mounted on the shaft. The elastic spring element can be slid onto the shaft, and then the retaining ring is installed.

[0020] It is also possible that the stop is formed directly by a shoulder of a groove formed in the shaft, against which the elastic element is supported. With this design, no separate component needs to be mounted to fix the elastic spring element axially on the shaft.

[0021] According to an alternative embodiment, the pump impeller can be arranged on a shaft that is axially displaceable away from the drive motor against the action of the elastic spring element. In this configuration, the pump impeller can be rigidly mounted on the shaft, so that no concentricity tolerances occur.

[0022] To solve the aforementioned problem, the invention also provides a water supply system for a caravan, comprising a water circuit and a peripheral impeller pump of the type described above. Reference is made to the above explanations regarding the resulting advantages.

[0023] The invention is described below with reference to various embodiments, which are illustrated in the accompanying drawings. These show:

[0024] Figure 1 shows a peripheral wheel pump according to a first embodiment in a partially cutaway side view;

[0025] Figure 2 shows the peripheral wheel pump of Figure 1 in a partially cutaway perspective view, with the housing part forming the pump chamber omitted;

[0026] Figure 3, enlarged to a larger scale, shows detail III of Figure 1;

[0027] Figure 4, enlarged to a larger scale, shows detail IV of Figure 2;

[0028] Figure 5 shows a peripheral impeller pump according to a second embodiment in a partially cutaway side view; Figure 6 shows the peripheral impeller pump of Figure 5 in a partially cutaway perspective view, with the housing part forming the pump chamber omitted;

[0029] Figure 7, enlarged to a larger scale, is detail VII of Figure 5; and Figure 8, enlarged to a larger scale, is detail VIII of Figure 6.

[0030] Figures 1 to 4 show a peripheral impeller pump 2 according to a first embodiment. The peripheral impeller pump 2 is, in particular, a water pump for a caravan's water circuit. The water circuit is indicated here by connections 4. The peripheral impeller pump 2 serves to circulate water in the water circuit when it is in operation.

[0031] The peripheral wheel pump 2 has a drive motor 5, which here is designed as an electric motor with a stator 6 and a rotor 8.

[0032] The rotor 8 can, in particular, be an injection-molded plastic part in which either permanent magnets or particles made of a ferromagnetic material are embedded. In the latter case, a strong magnetic field is applied to the rotor after it has been injection-molded, so that magnetic poles are formed.

[0033] Between the stator 6 and the rotor 8 is a pot-shaped inner wall 10, which is part of a motor housing 12. The stator 6 is arranged inside the pot-shaped inner wall 10, and the rotor 8 is arranged as an external rotor in an annular space 9 between the outside of the inner wall 10 and the inside of the motor housing 12.

[0034] A shaft 14, on which a pump impeller 16 is arranged, is rigidly connected to the rotor 8. The rotor mechanically engages in a recess 18 (see Figure 3) or similar design of the shaft 14, thus ensuring a rotationally fixed and axially fixed connection.

[0035] The shaft 14 is preferably cast into the rotor 8 during its manufacture. The shaft 14 is hollow and arranged on a bearing journal 20, which is fixed in the base 22 of the inner wall 10 of the motor housing 12. The bearing journal 20 is preferably cast into the inner wall 10.

[0036] At its end facing away from the drive motor 5, a retaining ring 24 is arranged on the bearing journal 20, so that the shaft 14 is fixed in the axial direction between the base 22 of the inner wall 10 of the motor housing 12 and the retaining ring 24.

[0037] The shaft 14 can be made of ceramic, resulting in low friction and low wear when the shaft 14 rotates on the bearing journal 20.

[0038] The impeller 16 is arranged in a pump chamber 26. In the circumferential direction and on the side facing away from the drive motor 5, the pump chamber 26 is defined by a pump housing 28.

[0039] In the embodiment shown, the pump housing 28 is an integral part of the water circuit with the connections 4.

[0040] Towards the drive motor 5, the pump chamber 26 is closed off by a partition 30, which is arranged between the motor housing 12 and the pump housing 28.

[0041] The partition 30 does not seal tightly in the area where the rotor 8 or the shaft 14 passes through, so that the annular space 9 is filled with water and flushed through during operation of the peripheral pump. The water serves to dissipate some of the waste heat from the drive motor 5.

[0042] The impeller 16 is mounted on the shaft 14 in a rotationally fixed but axially displaceable manner. A shaft-hub connection is used for this purpose. In the illustrated embodiment, the shaft 14 has a recess 32 into which a projection engages, the projection being formed on the inside of the opening of the impeller 16 through which the shaft 14 extends.

[0043] In the axial direction towards the drive motor 5, the pump impeller 16 is fixed by the partition 30. Alternatively, the pump impeller 16 can be fixed in the axial direction towards the drive motor 5 on the shaft 14, which in turn is fixed in the axial direction towards the drive motor 5 by contact with the base 22 of the inner wall 10.

[0044] In the axial direction away from the drive motor 5, the pump wheel 16 is fixed on the shaft by a combination of a stop 34 on the shaft 14 and an elastic spring element 36.

[0045] The stop 34 is formed here by a retaining ring which engages in a groove 38 which is provided on the outer circumference of the shaft 14 near its free end, which is associated with the retaining ring 24.

[0046] The elastic spring element 36 is formed here as a ring made of rubber or an elastomer with similar elastic properties.

[0047] The elastic spring element 36 allows the pump impeller 16 to move slightly away from the drive motor 5 from the normal position shown in the figures, against the restoring force exerted by the elastic spring element 36. This is particularly advantageous when the caravan, in which the peripheral impeller pump 2 and the associated water supply system are located, is not in use and the water in the peripheral impeller pump 2, especially in the annular space 9, freezes due to low outside temperatures.

[0048] Figure 1 shows the peripheral pump 2 in its installed position. At outside temperatures below the freezing point of water, the water inside the peripheral pump 2 freezes starting from the upper end of the annular space 9. As soon as the water located between the base 22 of the inner wall 10 and the partition 30 freezes, the partition is deformed away from the drive motor 5, since the increase in volume associated with freezing acts towards the unfrozen water; the ice above acts as a barrier.

[0049] The elastic spring element allows the impeller 16 to deflect downwards, towards the stop 34, when the partition wall deforms and exerts an axial force on the impeller 16. This ensures that the shaft 14 and its mounting are not damaged if the water inside the peripheral pump 2 freezes. When the water thaws and the partition wall 30 returns to its initial position, the restoring force of the elastic spring element 36 ensures that the impeller 16 also returns to its initial position.

[0050] As an alternative to the elastic spring element 36 shown here, a spiral spring or a wave spring can also be used, each arranged concentrically to the axis of rotation of the pump wheel 16 on the shaft 14 between the stop 34 and the pump wheel 16.

[0051] Figures 5 to 8 show a second embodiment. The same reference numerals are used for the components known from the first embodiment, and reference is made to the explanations above in this respect.

[0052] The difference between the first and second embodiments is that in the second embodiment the stop 34 is not formed by a separate component arranged on the shaft 14, but by a shoulder of the groove 38 formed on the outside of the shaft 14.

[0053] Accordingly, the elastic spring element 36, which here too is designed as a ring made of rubber or an elastomer with rubber-like properties, has a guide inner section whose inner diameter corresponds approximately to the outer diameter of the shaft 14, and a support inner section whose inner diameter is smaller than the outer diameter of the shaft 14. The support inner section of the elastic spring element 36 engages in the groove 38, so that its side facing away from the drive motor 5 is supported against the shoulder of the groove 38, which acts as a stop 34.

[0054] The effect of the elastic spring element 36 is the same in the second embodiment as in the first: the pump impeller 16 can be elastically displaced away from the drive motor 5 on the shaft 14 when corresponding axial forces are applied, and it is returned to its initial position by the elastic spring element 36 when the axial forces are no longer applied. According to an embodiment not shown, it is also conceivable that the shaft 14 is mounted so as to be axially displaceable, while the pump impeller 16 is mounted on the shaft 14 so that it is both rotationally and axially fixed. In this case, an elastic spring element is installed between the shaft 14 and the retaining ring 24.

Claims

Patent claims 1. Peripheral impeller pump (2) comprising a drive motor (5), an impeller (16) coupled to the drive motor (5), and a partition (30) arranged between the drive motor (5) and the impeller (16), wherein the drive motor (5) is designed as an electric motor with a stator (6) and a rotor (5), and the rotor (5) is arranged in an annular space (9) which is separated from a pump chamber (26) in which the impeller (16) is arranged by the partition (30), wherein the partition (30) allows the annular space (9) to be flushed with water during operation of the peripheral impeller pump (2) in order to dissipate some of the waste heat from the drive motor (5), characterized in that an elastic spring element (36) is provided which allows the impeller (16) to move away from the drive motor (5).

2. Peripheral wheel pump (2) according to claim 1, characterized in that the elastic spring element (36) consists of rubber or an elastomer.

3. Peripheral wheel pump (2) according to claim 1, characterized in that the elastic spring element (36) consists of spring-elastic metal.

4. Peripheral wheel pump (2) according to one of the preceding claims, characterized in that the elastic spring element (36) is a ring.

5. Peripheral impeller pump (2) according to one of the preceding claims, characterized in that the impeller (16) is arranged on a shaft (14) which is supported at least against axial movement away from the drive motor (5), and that the elastic spring element (36) enables axial movement of the impeller (16) relative to the shaft (14).

6. Peripheral wheel pump (2) according to claim 5, characterized in that the elastic spring element (36) is arranged between a stop (34) associated with the shaft (14) and the pump wheel (16).

7. Peripheral wheel pump (2) according to claim 6, characterized in that the stop (34) is a retaining ring which is arranged on the shaft (14).

8. Peripheral wheel pump (2) according to claim 6, characterized in that the stop (34) is a shoulder of a groove (38) formed in the shaft (14).

9. Peripheral impeller pump (2) according to one of claims 1 to 4, characterized in that the pump impeller (16) is arranged on a shaft (14) which can be displaced in the axial direction away from the drive motor (5) against the action of the elastic spring element (36).

10. Water supply system of a caravan, comprising a water circuit and a peripheral impeller pump (2) according to one of the preceding claims.

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