EP2162045B1 - Dishwashing machine with a pump with a brushless permanent magnet motor - Google Patents

Description

The invention relates to a dishwasher with at least one conveying device for conveying rinsing liquor, wherein the conveying device has at least one pump with a brushless permanent magnet motor.

Pumps of conveyors of dishwashers are usually designed as shaded-pole motors or synchronous motors. Shadow pole motors have the advantage of a high delivery capacity and a defined running direction. It is therefore possible to arrange the outlet tangentially to a pump housing. The problem with the use of shaded-pole motors is the fact that they are mostly so-called dry-runners, as a result of which complex sealing measures are necessary. If the tightness can not be maintained, the pump may fail.

On the other hand, synchronous motors are usually so-called wet runners, so that a pump can be constructed in a structurally simpler way, since no such complex sealing measures are necessary. Due to the principle, the direction of rotation of an impeller of the pump can not be determined. This has the advantage, on the one hand, that in the event of blockage, e.g. when pumping out of food residues, by changing the direction of rotation of the impeller there is a chance that the blockage is solvable. On the other hand, the randomly adjusting running direction of the impeller requires a central arrangement of the outlet on the pump housing. Due to the flow dynamics unfavorable arrangement can be provided with synchronous motors low compared to shaded pole low flow rate.

Brushless DC, brushless AC, permanent magnet synchronous motors) are also known from the prior art, which have been proposed for use in washing machines and dishwashers. The rotor of a brushless permanent magnet motor consists of one or more permanent magnets, the stator consists of several electromagnets. The Electromagnets in the stator are commutated via a control electronics, eg with a block or sinusoidal commutation. Brushless permanent magnet motors therefore have the advantage that the direction of rotation of the stator, with which the impeller of the pump is rotatably connected, is adjustable by the control electronics. Furthermore, the capacity of a pump with a brushless permanent magnet motor can be controlled by adjusting the speed of the stator.

The use of brushless permanent magnet motors in household appliances is known in principle from the prior art.

From the DE 195 33 076 A1 a circuit for driving a brushless synchronous motor for a pump in a washing machine is known.

The DE 198 46 831 A1 discloses a method for determining the rotor position of synchronous motors.

JP 2004278539 A suggests the use of a pump with a brushless motor in a dishwasher. The dishwasher shown there uses to circulate the rinsing liquor in a closed water cycle and to pump out the rinsing liquor from the dishwasher of a single pump.

The EP 1 502 535 A2 describes a circulating pump with a brushless motor, with which the fluid flow is controlled in a dishwasher. In particular, it is possible to apply optionally the upper basket, the lower basket or both baskets with rinsing liquor.

Further, the JP 2001276479 A a pump having a brushless motor having an axially disposed inlet and an outlet tangentially disposed on the pump housing.

The DE 103 39 130 A1 discloses a household appliance such as a washing machine or dishwasher with a liquid circuit in which the control of the drive motors for the liquid pump is thereby cost-effectively improved that at least one of the two pumps can be connected to a control unit for the engine control and / or regulation.

Furthermore, the disclosed DE 10 2004 003 536 A1 a household electrical appliance having a chamber at least partially filled with liquid during operation of the apparatus, a pump driven by a motor for aspirating liquid from the chamber, and monitoring means for detecting speed and power of the motor, comparing sensed values of speed and Power with a given characteristic and for signaling a state of emergency when the comparison shows that the detected values deviate significantly from the characteristic.

The EP 0 268 835 A2 shows a pump unit with a shaft mounted on the separate rotor wheels of the drain pump and the circulation pump and working with opposite directions.

It is an object of the present invention to provide a dishwasher, which has improved operating characteristics and at the same time is economical to produce.

This object is achieved by a dishwasher with the features of claim 1. Advantageous embodiments result from the dependent patent claims.

In a dishwasher according to the invention with at least one conveying device for conveying washing liquor, the conveying device having at least one pump with a brushless permanent magnet motor, the conveying device comprises a first pump and a second pump each having a brushless permanent magnet motor, in particular a brushless DC motor. Furthermore, a common control electronics for the first and the second pump of the conveyor is provided.

The use of pumps with a brushless permanent magnet motor, particularly a brushless DC motor, allows substantial hydraulic improvements in a dishwasher water cycle. This is realized essentially by an optimizable shape of a pump housing of the pump. Because of that Pumps with a brushless permanent magnet motor achieve a higher delivery rate, which is also freely adjustable by the speed. Since pumps with a brushless permanent magnet motor are so-called wet runners, costly sealing measures of the pump are eliminated. Usually motors with brushless permanent magnet motors are each assigned their own control electronics. By the inventive approach, the first and the second pump to assign a common control electronics, however, the higher costs can be partially compensated.

According to one embodiment, the control electronics is designed to operate the first and the second pump of the conveyor alternately. It is therefore sufficient to use the components necessary for driving the brushless permanent magnet motor, e.g. a bridge circuit of MOS-FET transistors IGBT (Insulated Gate Bipolar Transistor) or other switching elements, only once to provide and alternatively to control the first or the second pump. A simultaneous operation of the first and the second pump is not provided.

The term of the alternating operation of the first and the second pump of the conveyor is to be understood in the context of the present invention that between the operation of the one and then the other pump an arbitrarily long period may exist, in which neither of the two pumps is operated. On the other hand, however, should also include the possibility that immediately after the end of the operation of a pump, the other pump can be operated.

While the first pump is a drain pump, with which the wash liquor from the washing container is conveyed, the second pump is a circulation pump of the dishwasher, with which the wash liquor is conveyed into a closed water cycle of the dishwasher. According to the invention, the drive electronics comprise a converter electronics for driving and feeding the conveyor.

According to the invention, the drive electronics are designed to detect the position of the rotor of the brushless permanent magnet motor and, upon detection, one of a set speed or a set speed range Deviating actual speed to change the direction of rotation of the rotor. The detection of the position of the rotor of the brushless permanent magnet motor is in this case possible by design without additional sensor device. The position of the rotor can be measured, for example, via a retroactive induction voltage or via the resulting current. The determination of the rotor position is known in principle to those skilled in the art, so that at this point a detailed description is dispensed with. Based on this information, the control electronics is able to detect a deviation of the rotational speed from the target rotational speed or the target rotational speed range. If there is such a deviation, this suggests a blockage, which may be caused, for example, in the drain pump by residual scavenging agent to be pumped or the like. By changing the direction of rotation, for example, an alternating change of the direction of rotation, which can be selectively controlled by the control electronics, it is possible to solve such a blockage of the pump.

According to a further embodiment, the control electronics is adapted to make a turn off the first and / or the second pump when a predetermined time has elapsed since the start of the first and / or the second pump. In other words, this means that the first and / or the second pump with a Time control can be operated, with a targeted switching on and off is possible at defined times. In contrast, this is not possible with pumps with a synchronous motor, since there may be an indefinite period of time until the pump starts up due to the randomly setting direction of rotation of the rotor. Due to this, dishwashers with synchronous motors are operated beyond the duration of the actual pumping process for an additional time, for example 30 seconds. By saving this additional operating time of the pump, an energy saving and noise reduction can be realized.

In another embodiment, the control electronics is adapted to make a turn off the first and / or the second pump when a predetermined speed criterion is met. The speed criterion may be an exceeding of a predetermined speed. Alternatively, the speed criterion may be the detection of a speed increase by a predetermined speed difference. This approach is based on the finding that the speed increases as soon as air is delivered by the pump, i. the actual conveying process of the rinsing liquor is completed.

In accordance with a further preferred embodiment, the first and / or the second pump have an inlet arranged centrally and axially with respect to the shaft of an impeller and an outlet arranged tangentially on a housing of the first and / or second pump. In particular, by the tangentially arranged on the housing outlet a significant improvement of the hydraulic conditions is achieved. As a result, a pump having a brushless permanent magnet motor can achieve higher output as compared with a conventional pump (be it a pump with a split motor or a synchronous motor).

Due to the possibility of being able to operate a pump with a brushless permanent magnet motor at a defined speed, it is also possible to make the impeller rotatably connected with the rotor more streamlined. As a result, a further increase in the capacity is possible.

These measures make it possible to generate a higher pressure at the outlet of the pump. As a result, on the one hand in the closed water cycle through the Circulating pump funded rinse liquor are sprayed with a higher pressure on the items to be washed, thereby increasing the cleaning effect. On the other hand, in a suitably designed drain pump, a larger delivery height can be achieved compared to pumps with shaded-pole or synchronous motors. This means that the household connection can be moved upwards compared to the current state of the art. On the other hand, however, the dimensioning of the pump can be adapted to the currently achievable delivery heights, whereby the manufacturing cost of the dishwasher according to the invention can be reduced.

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Geschirrspülmaschine, und

Fig. 2

eine schematische Darstellung einer in der erfindungsgemäßen Geschirrspülmaschine einsetzbaren Pumpe mit einem bürstenlosen Permanentmagnetmotor in einem Querschnitt.

The invention will be explained below with reference to the figures. Show it:

Fig. 1

a schematic representation of a dishwasher according to the invention, and

Fig. 2

a schematic representation of a usable in the dishwasher according to the invention pump with a brushless permanent magnet motor in a cross section.

In Fig.1 1 is a cross-sectional view of a dishwasher 1 according to the invention shown in a schematic form. This has a washing container 2 in a known manner. In the washing container 2 two spray arms 3, 4 are arranged in a known manner, which are associated in a known manner, not shown baskets. The rinsing liquor impinging on the ware also not shown is supplied from a rinsing tank 16 to a sump 17. The pump pot 17 is connected on the output side via a line 12 or 13 to a drain pump 5 or to a circulating pump 6. The outlet of the circulation pump 6 is connected in a known manner via a line 8 and 9 with the spray arm 3 and 4 respectively. An outlet of the drain pump 5 is connected to an outlet 20 of the dishwasher, so that the conveyed from the drain pump 5, provided with impurities rinsing liquid via a line 18 to one in a wall 21 located house connection 19 can be promoted, with a predetermined height difference between the outlet 20 and house connection 19 is overcome.

The operation and the control of the drain pump 5 and the circulation pump 6 takes place in accordance with a common control electronics 7. This is coupled via a control line 14 to the drain pump 5 and a control line 15 to the circulation pump 6. The control electronics include u.a. a converter electronics, e.g. a bridge circuit for driving and feeding the drain pump 5 or the circulation pump 6. The converter electronics is provided only once in the control electronics 7. This is sufficient because the drain pump 5 or the circulation pump 6 are never operated simultaneously, but alternately in accordance with the program control unit.

In Fig. 2 is a schematic representation of an exemplary structure of a pump 30 with a (not shown) brushless permanent magnet motor shown. The pump 30 may represent the drain pump 5 and / or the circulating pump 6. As permanent magnet motors, in principle, all known types come into consideration, such as brushless DC motors (BLDC), brushless AC motors (BLAC) or permanent magnet synchronous motors (PMSM). Preferably, brushless DC motors are used. A pump housing 35 is provided with an inlet 31 arranged axially to a shaft of an impeller 33 and a tangentially arranged outlet 32. With A the direction of rotation of the impeller 33 is marked. With B is the direction of rotation A achieved during operation of the pump 30 in the flow direction. In addition to the fact that the speed of the impeller 33 is inherently freely adjustable by the control electronics, such an arrangement has only small hydraulic resistances to be overcome at the outlet, so that the pump 30 has a high delivery capacity compared to conventional pumps. This can be further improved by the shape of the exemplary four wings 34 of the impeller 33. The optimum number and shape of the wings 34 can be determined by known means by simulations.

The use of a circulation pump with a brushless permanent magnet motor therefore allows a higher, maximum pressure to be reached at the nozzles of the spray arms, which compared to conventional dishwashers the Cleaning effect is improved. If too high a pressure is undesirable, eg with delicate dishes, this can be reduced by simple speed control (reduction of the pump speed).

The use of a brine pump with a brushless permanent magnet motor allows overcoming a greater height difference between the outlet 20 of the dishwasher and the domestic connection 19 in the wall 21 due to the higher delivery capacity compared to conventional pumps, whereby the house connection 19 placed in the wall 21 elsewhere could be. On the other hand, if the height difference between the outlet 20 of the dishwasher and the domestic connection 19 remains such that it is designed for conventional state-of-the-art dishwashers, then the dimensioning of the drain pump 5 can be adapted to this height difference. This results in a structurally reduced drainage pump. In addition to reduced manufacturing costs is thus more space for other components in the dishwasher available.

If the structural conditions do not permit the provision of an outlet arranged tangentially on the pump housing, it is also possible to arrange the outlet elsewhere, e.g. centrally arranged to provide.

The present invention thus provides a dishwasher which is more economical to manufacture in addition to improved operating characteristics.

LIST OF REFERENCE NUMBERS

1

dishwasher

2

rinse tank

3

spray arm

4

spray arm

5

pump

6

pump

7

control electronics

8th

management

9

management

12

management

13

management

14

control line

15

control line

16

wash tub

17

sump

18

management

19

House connection

20

outlet

21

wall

30

pump

31

pump inlet

32

pump outlet

33

impeller

34

wing

35

pump housing

Claims (9)

1. Dishwashing machine having at least one pumping device for pumping dishwashing solution, wherein the pumping device has at least one pump with a brushless permanent magnet motor, wherein the pumping device has at least a first pump (5; 30) and a second pump (6; 30), each having a brushless permanent magnet motor, in particular a brushless direct current motor (brushless DC, BLDC), and a shared electronic controller (7) is provided for the first and second pump of the pumping device and wherein the electronic controller (7) comprises an electronic frequency converter for driving and supplying power to the pumping device, characterised in that the electronic controller (7) is designed to detect the position of the rotor of the brushless permanent magnet motor, and to change the direction of rotation of the rotor on detecting an actual speed that differs from a target speed or from a target speed range.
2. Dishwashing machine according to claim 1, characterised in that the electronic controller (7) is designed to operate the first pump and the second pump (5, 6; 30) of the pumping device in an alternating manner.
3. Dishwashing machine according to claim 1 or 2, characterised in that the first pump (5; 30) is a drain pump, which can be used to pump the dishwashing solution out of the dishwashing tub (2).
4. Dishwashing machine according to any of the preceding claims, characterised in that the second pump (6; 30) is a circulating pump, which can be used to pump the dishwashing solution in a closed water circuit of the dishwashing machine (1).
5. Dishwashing machine according to any of the preceding claims, characterised in that the electronic controller (7) is designed to switch off the first pump and/or the second pump (5, 6; 30) when a defined time has passed since the first pump and/or the second pump (5, 6; 30) starts running.
6. Dishwashing machine according to any of the preceding claims, characterised in that the electronic controller (7) is designed to switch off the first pump and/or the second pump (5, 6; 30) when a defined speed criterion is met.
7. Dishwashing machine according to claim 6, characterised in that the speed criterion is a defined speed being exceeded.
8. Dishwashing machine according to claim 6, characterised in that the speed criterion is the detection of an increase in speed by a defined speed difference.
9. Dishwashing machine according to any of the preceding claims, characterised in that the first pump and/or the second pump (5, 6; 30) have an inlet (31) arranged centrally and axially to the shaft of an impeller, and an outlet (32) arranged tangentially on a housing of the first pump and/or second pump (5, 6; 30).

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