Ice maker for a domestic refrigeration appliance

Abstract

An ice maker for a household refrigeration appliance is proposed, which comprises an ice making tray arranged to rotate about an axis of rotation and a drive unit for driving the ice making tray in rotation. The drive unit has an electric motor, the operation of which is controlled by a drive control system depending on the electric current consumption of the electric motor.

Claims

1. An ice maker for a household refrigerating appliance, the ice maker comprising: an ice making tray arranged to rotate about an axis of rotation; a drive unit for driving the ice making tray in rotation, wherein the drive unit comprises an electric motor; and a drive control system configured to control operation of the electric motor depending on an electric current consumption of said electric motor.

2. The ice maker according to claim 1, wherein the drive control system is configured to stop running of the electric motor depending on the fact that a current behavior is detected for the electric current consumption of the electric motor which is characteristic of a proper moving towards and/or reaching of a defined rotational state of the ice making tray.

3. The ice maker according to claim 2, wherein the defined rotational state is a final rotational state of the ice making tray.

4. The ice maker according to claim 3, wherein the final rotational state of the ice making tray is determined by mechanical stop limitation of a movement path of a component arranged in a power transmission path from the electric motor to the ice making tray.

5. The ice maker according to claim 4, wherein the component is arranged upstream of the ice making tray in a direction of power flow.

6. The ice maker according to claim 5, wherein the component is a gear pinion of a reduction gear.

7. The ice maker according to claim 3, wherein a different nominal current behavior of the electric current consumption of the electric motor for the proper moving towards and/or reaching of the final rotational state is predetermined in mapping to each of two final rotational states of the ice making tray.

8. The ice maker according to claim 2, wherein the drive control system is configured to stop running of the electric motor when the ice making tray is rotated from a horizontal position in a direction of an emptying rotational state, depending on the fact that a current increase behavior characteristic of a proper moving towards and/or reaching of the emptying rotational state is determined for the electric current consumption of the electric motor.

9. The ice maker according to claim 8, wherein the drive control system is configured to take into account the current increase behavior during such a part of the rotational movement path of the ice making tray on which the ice making tray undergoes a twisting which ensures or promotes breaking away of pieces of ice from the ice making tray in order to assess whether the current increase behavior characteristic of the proper moving towards and/or reaching of the emptying rotational state is present.

10. The ice maker according to claim 1, wherein the drive control system is configured to: determine a current angle of rotation of the electric motor and/or the ice making tray based on the electric current consumption of the electric motor; and control the electric motor as a function of the current angle of rotation.

11. The ice maker according to claim 10, wherein the drive control system is configured to determine the current angle of rotation on the basis of a cumulative current consumption of the electric motor within a past time interval.

12. The ice maker according to claim 10, wherein the drive control system is configured to: determine a rotational speed of the electric motor and/or the ice making tray for each measuring time based on the electric current consumption of the electric motor at a plurality of measuring times within a past time interval; and determine the current angle of rotation on the basis of the rotational speeds.

13. The ice maker according to claim 1, wherein: the drive unit is installed in a module housing of a drive module, which is designed with a coupling piece rotatably mounted on the module housing and in rotary drive connection with the drive unit; the coupling piece forms a mechanical interface, accessible from outside the drive module, for the detachable torsional force-transmitting coupling of the ice making tray to the drive module; the module housing has an opening through which an electrical conductor arrangement connected to the drive unit is led out of the module housing; and at least one of the following measures is taken: the mechanical interface and the opening are formed on opposite sides of the module housing; the conductor arrangement is formed by a circuit board; and/or the module housing has at least one positioning formation on the outside of the module housing near the opening for positioning a control board that is in electrical contact with the conductor arrangement.

14. The ice maker according to claim 13, wherein the at least one positioning formation is pin-like in configuration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention is explained further below with reference to the accompanying drawings. They show:

[0020] FIG. 1 in perspective an ice maker according to an embodiment example, whereby a control board mounted on a drive module of the ice maker is not shown,

[0021] FIG. 2 the ice maker of FIG. 1 together with the control board,

[0022] FIG. 3 the drive module of the ice maker of FIGS. 1 and 2 in a perspective view of the module side on which the control board of FIG. 2 is placed on the drive module,

[0023] FIG. 4 a perspective view of the drive module of FIG. 3 on an opposite side of the module, on which a coupling piece protrudes,

[0024] FIG. 5 an interior view of the drive module of FIGS. 3 and 4,

[0025] FIG. 6 an enlarged view of the control board in its installation situation as shown in FIG. 2,

[0026] FIG. 7a an exemplary qualitative current-time characteristic curve of the electric current drawn by an electric motor of the drive module of the ice maker of FIGS. 1 and 2 when an ice making tray of the ice maker is rotated from a horizontal position to an emptying rotational state,

[0027] FIG. 7b an exemplary qualitative current-time characteristic of the motor current when the ice making tray is rotated back from the emptying rotational state to the horizontal position, and

[0028] FIG. 7c an exemplary qualitative current-time characteristic of the motor current in the event of unforeseen premature blocking of the ice making tray.

DETAILED DESCRIPTION

[0029] Reference is first made to FIGS. 1 and 2. The ice maker shown there is generally designated 10 and is intended for installation in a household refrigeration appliance. The household refrigeration appliance may, for example, be a refrigerator with a freezer compartment in which, in addition to accommodating the ice maker 10, there may optionally also be space for the frozen storage of food. Alternatively, the household refrigeration appliance can be a pure freezer that is used exclusively for the frozen storage of food. The ice maker 10 comprises an ice making tray 12, which is held rotatably about an axis of rotation 14 in a frame 16. The frame 16 is designed in a manner not shown in detail with mounting formations which serve to install the frame 16 in the refrigeration appliance 10. The ice making tray 12 has a plurality of trays (hereinafter referred to as bags) 18, each of which can be filled with water and each of which is used to produce an ice cube. In the example shown, the bags 18 are distributed over two rows extending along the axis of rotation 14. It is understood that the bags 18 may be arranged in any other distribution in the ice making tray 12.

[0030] Insofar as the term ice cube is used in the context of the present disclosure, this is in no way intended to be limited to a geometric cube shape of the ice pieces produced. Rather, the term is to be understood in the colloquial sense as designating any geometric shape of ice pieces, such as may be provided by recesses in an ice making tray.

[0031] In FIGS. 1 and 2, the ice making tray 12 is shown in a freezing position in which it assumes a horizontal orientationin the installation situation of the ice maker 10in which the bags 18 can be filled with water and the freezing process is carried out. After the water in the bags 18 has completely frozen through, the ice making tray 12 is rotated relative to the frame 16 into an emptying rotational state, not shown in detail in the figures, in which the frozen pieces of ice can fall out of the bags 18 by gravity into a collecting container (not shown) located under the ice making tray 12. The ice maker 10 operates according to the twisted tray principle (i.e., the ice making tray 12 is so flexible that it can be twisted about the axis of rotation 14). This twisting ensures that the ice cubes in the bags 18 break away from the surface of the tray material, so that in the (twisted) emptying rotational state of the ice making tray 12, the ice cubes can fall out of the ice making tray 12 without further action.

[0032] The twisting of the ice making tray 12 is effected by blocking it against further rotation from a certain angle of rotation in the area of a tray longitudinal end remote from the drive. In the area of a tray longitudinal end close to the drive end, on the other hand, the ice making tray 12 can be rotated beyond this angle of rotation into the emptying rotation state. In FIGS. 1 and 2, the longitudinal end of the ice making tray 12 close to the drive end is the left-hand end of the tray. A drive module 20 (FIG. 1), which is shown in more detail in FIGS. 3, 4, and 5, is located there in a receiving chamber formed by the frame 16. Reference is now made to these figures as a supplement.

[0033] The drive module 20 has a module housing 22 in which a drive unit 23 (see FIG. 5) with an electric motor 24 and a reduction gear 26 is accommodated. The reduction gear 26 has a pinion 28 on the output side, which has a plug-in mount 30 for a coupling piece 32 (FIG. 4), which is provided for torque-transmitting coupling with the ice making tray 12. In the assembled state of the drive module 20, the coupling piece 34 protrudes through an opening 36 in the module housing 22 on the module side facing the ice making tray 12 and forms a mechanical interface for the detachable plug-in connection of the ice making tray 12 to the drive module 20.

[0034] In the example shown, the pinion 28 of the reduction gear 26 has an arc-shaped recess 38 (FIG. 5) which extends over a pitch circle and is closed at both ends and into which a stop body 40, which is stationary relative to the module housing 22 and in this example is designed in the form of a pin or bolt, projects. The stop body 40 forms a mechanical stop limit for the rotation of the pinion 28 in both directions of rotation of the pinion 28 and thus also for the rotation of the ice making tray 12 in the region of its longitudinal end close to the drive end of the tray. In the example shown, the arc length of the recess 38 is approximately 180 degrees; this means that the ice making tray 12 can be rotated by this angle in the region of its tray longitudinal end close to the drive end. In the area of the tray longitudinal end of the ice making tray 12 remote from the drive end, the rotational movement path of the ice making tray 12 can be shortened in order to ensure the torsion of the ice making tray 12 as explained.

[0035] For this purpose, for example, a stop not shown in detail can be formed on the frame 16, against which the ice making tray 12 abuts in the region of its tray longitudinal end remote from the drive, after it has been rotated from the horizontal position by a certain angle of rotation, which is less than the angular length of the arc-shaped recess 38. For example, the available range of rotation angles in the region of the tray longitudinal end remote from the drive can be only about 90 degrees. It will be understood that the figures disclosed herein for the range of angular rotation of the ice making tray 12 in the region of its two tray longitudinal ends are exemplary only and are not to be construed as limiting in any way.

[0036] The mentioned emptying rotational state of the ice making tray 12 means the rotational state in which the ice making tray 12 has been rotated as far as possible from the horizontal position in the area of its tray longitudinal end close to the drive. The horizontal position and the emptying rotational state therefore correspond to the two arc ends of the arc-shaped recess 38 in the embodiment example shown.

[0037] It will be understood that a mechanical rotation limiting device for the drive end of the ice making tray 12 can alternatively be provided elsewhere in the power transmission path leading from the electric motor 24 to the ice making tray 12. For example, such a mechanical rotation limitation can be realised at a pinion of the reduction gear 26 other than the pinion 28. According to yet another alternative, a suitable stop formation could be formed on the frame 16 in spatial association with the longitudinal end of the ice making tray 12 close to the drive, which serves as a rotation limiting stop for the ice making tray 12.

[0038] In the embodiment example of the ice maker 10 shown, a control board 42 (FIGS. 2 and 6) is placed on the drive module 20, on which various electrical and electronic components 43 (FIG. 6) are mounted. In the example shown, these components 43 include at least one integrated circuit which implements a microprocessor-based drive control unit 44, as well as a power supply unit 45 for generating a DC supply voltage from an AC mains voltage supplied via a harness 46, with which the domestic refrigeration appliance is supplied from an electrical supply network. The control board 42 with the drive control unit 44 is used to control the operation of the electric motor 24. A small-format circuit board 48 establishes the electrical connection between the electric motor 24 and the control board 42. The electric motor 24 is supplied with electric current from the control board 42 via the circuit board 48. The circuit board 48 protrudes from an opening 50 of the module housing 22 and is firmly connected to the electric motor 24, for example by soldering. A slit 52 (FIG. 6) is formed in the control board 42, into which the circuit board 48 is inserted when the control board 42 is attached to the drive module 20. Electrical strip conductors (not shown in detail) may be formed at the edges of the slit 52, which come into electrical contact with strip conductors 54 on the circuit board 48 when the circuit board 48 is inserted into the slit 52. It is understood that other techniques for contacting the strip conductors 54 are also conceivable, for example by means of resilient metal laminations arranged on the control board 42.

[0039] For precise positioning of the control board 42 relative to the circuit board 48 during assembly of the ice maker 10, a positioning pin 56 protrudes from the module housing 22 of the drive module 20 in close proximity to the circuit board 48. When the control board 42 is installed, this engages in a cross-sectionally complementary positioning hole 58 (FIG. 6) in the control board 42. It is understood that, in addition to the positioning pin 56, further positioning formations may be formed on the drive module 20 or/and on the control board 42 in order to ensure precise positioning of the control board 42 relative to the circuit board 48 and thus reliable electrical contacting of the strip conductors 54 formed on the circuit board 48.

[0040] In other embodiments, not shown in detail, the circuit board 48 may be omitted and another form of electrical contacting of the electric motor 24 with the control board 42 may be provided. For example, it is conceivable to use electrically conductive pin bodies, spring elements or similar components.

[0041] The control board 42 with its components 43 mounted thereon has a measuring function for measuring the electric current consumption of the electric motor 24. For this purpose, it can either directly measure the current flowing to the electric motor 24 via the circuit board 48 or measure the current in another circuit branch of the electrical circuit formed on the control board 42, provided that the current flowing there is representative of the current consumption of the electric motor 24. Depending on the measured current, the drive control unit 44 is set up to control the operation of the electric motor 24 and, in particular, to cause the electric motor 24 to stop if, when the ice making tray 12 rotates from one of its final rotational states (horizontal position, emptying rotational state) to the respective other final rotational state, the measured current consumption of the electric motor 24 is used to recognise that this other final rotational state has been reached or an unforeseen malfunction event has occurred. For this purpose, the drive control unit 44 can compare the time course of the measured current consumption of the electric motor 24 with one or more predetermined characteristic curves, which are characteristic of the proper starting and/or reaching of the respective final rotational state of the ice making tray 12, at least in certain rotational angle ranges of the ice making tray 12. In this regard, reference is now made to FIGS. 7a, 7b, and 7c.

[0042] FIG. 7a shows an example of a qualitative current-time characteristic curve, which is characteristic of the current consumption (motor current IM) of the electric motor 24 during a proper rotation of the ice making tray 12 from the horizontal position to the emptying rotational state. At a time t1 the electric motor 24 is started and the ice making tray 12 begins to move away from the horizontal position. The mechanical load on the electric motor 24 is initially comparatively low and does not change significantly, which is why the current IM flowing through the electric motor 24 is comparatively constant. From a certain angle of rotation, the ice making tray 12 begins to twist, which is accompanied by an increase in the mechanical load acting on the electric motor 24; accordingly, the current flowing through the electric motor 24 increases. In the characteristic curve shown in FIG. 7a, the twisting of the ice making tray 12 begins at a time t2. The characteristic curve shown from time t2 is based on the assumption that the mechanical load acting on the electric motor 24 increases with increasing torsion of the ice making tray 12, so that an increasingly larger current consumption IM of the electric motor 24 can be observed with increasing torsion of the ice making tray 12. At a time t3, the emptying rotational state of the ice making tray 12 is finally reached, in which the stop body 40 prevents further rotation of the ice making tray 12. The current consumption IM of the electric motor 24 therefore increases rapidly from time t3. The time span from t1 to t3 is, for example, several seconds to several tens of seconds or even longer.

[0043] FIG. 7b shows in qualitative form an exemplary current-time characteristic curve of the electric motor 24 for a proper reverse rotation of the ice making tray 12 from the emptying rotational state to the horizontal position. At a time t4, the electric motor 24 is energised and the ice making tray 12 begins to move away from the emptying rotational state. Initially, the torsion of the ice making tray 12 supports the work of the electric motor 24 until the torsion of the ice making tray 12 disappears again from a time t5. As soon as the ice making tray 12 reaches its horizontal position and the stop body 40 prevents further rotation, the motor current IM increases abruptly. This is shown in FIG. 7b at a time t6. The time span between the points in time t4 and t6 can correspond approximately to the time span between the points in time t1 and t3, although this is not necessary and the reverse rotation of the ice making tray 12 can be faster or slower than its rotation from the horizontal position to the emptying rotational state.

[0044] Characteristic curves such as those shown in FIGS. 7a and 7b, or at least sections of such characteristic curves, may be stored in the drive control unit 44 or elsewhere in a memory and, in certain embodiments, may serve as a reference for the measured motor current IM. In these embodiments, if the time curve of the measured motor current IM shows a sufficient similarity with one of the predetermined reference characteristic curves, the electric motor 24 is operated by the drive control unit 44 until the relevant final rotational state of the ice making tray 12 is reached (i.e., either the horizontal position or the emptying rotational state).

[0045] FIG. 7c qualitatively shows an exemplary current-time characteristic curve of the motor current IM for the case that, starting from a rotation of the ice making tray 12 from the horizontal position (starting time t7), a premature, unforeseen blocking of the ice making tray 12 occurs before it has reached the emptying rotational state (and before the twisting of the ice making tray 12 also begins). The blockage of the ice making tray 12 becomes noticeable at a time t8 in a sharp increase in the motor current IM. The absolute magnitude of the motor current IM alone would not provide any reliable information about the current rotational state of the ice making tray 12. In conjunction with further information, however, the drive control unit 44 can judge whether the drastic increase in the motor current IM is due to an irregular state (fault) or whether the emptying rotational state has been reached.

[0046] In certain embodiments, this further information may relate to the time dimension. For example, a certain (minimum) time period from the start of the rotation process until the emptying rotation state is reached may be defined for a proper emptying process of the ice making tray 12. If a current magnitude and/or a current increase is measured before this time period has elapsed, which indicates a mechanical blockage in the power transmission train from the electric motor 24 to the ice making tray 12 (as in FIG. 7c at time t8), the drive control unit 44 can conclude from this that the blockage is not due to the emptying rotation state being reached, but that an irregular situation must have occurred. The drive control unit 44 will then immediately stop the electric motor 24 from running. Alternatively or additionally, for a proper emptying process of the ice making tray 12, it may be specified that during a certain partial phase of the emptying process, the measured motor current IM must increase with a certain constant or varying gradient. Such a gradual increase in the motor current IM occurs during the twisting phase of the ice making tray 12 (from time t2 in FIG. 7a). If the measured motor current IM does not show such a gradual increase or if it shows an increase with a different, significantly deviating gradient, this may also be an indication of an irregular state for the drive control unit 44.

[0047] Consideration of the time dimension alone may be prone to errors if the electric motor 24 does not exhibit sufficiently stable speed behaviour. If the speed behaviour of the electric motor 24 fluctuates, the current rotational state of the ice making tray 12 cannot always be reliably inferred from the elapsed time alone. Certain embodiments therefore provide for alternatively or additionally using one or more other measurable parameters in the determination in order to draw conclusions about the current rotational state of the ice making tray 12. For example, it is conceivable to calculate the current angle of rotation of the ice making tray 12 on the basis of the motor current and the voltage. In particular, the motor current and the motor voltage can be recorded at periodic points in time (e.g., every millisecond), and a respective rotational speed can be determined for each of the points in time using a predetermined assignment of motor current and motor voltage values to rotational speed values. This makes it possible to determine the rotation speed over time, which in turn makes it possible to determine the current rotation angle, provided that the rotation angle at a previous point in time is known (e.g., a rotation angle of 0 at the start of the rotation of the ice making tray from its horizontal position). The predetermined mapping can also be adjusted, for example if it is determined that the mapping indicates a current rotation angle that is greater than a maximum possible rotation angle of the ice making tray 12 (e.g., a maximum rotation angle of) 180. Such readjustment of the assignment or correlation between power consumption and rotational speed is particularly advantageous if a low-cost electric motor is used whose speed behaviour changes over time with the same power consumption.

[0048] If a significantly increased current magnitude and/or a significantly increased gradient of the motor current is measured during the rotary operation of the ice making tray 12, it can be concluded from the calculated current angle of rotation of the ice making tray 12 whether one of the nominal final rotational states of the ice making tray 12 (horizontal position, emptying rotational state) has been properly reached or whether an irregular blockage has occurred. The current angle of rotation can therefore also be used to analyse faults.

[0049] In the embodiment example shown in FIGS. 1 to 6, the electrical and electronic components responsible for measuring and analysing the motor current and controlling the operation of the electric motor 24, in particular the drive control unit 44, are structurally combined with the drive module 20. Deviating from this, a decentralised control solution is of course also conceivable, in which the ice maker 10 is designed without the control board 42 and instead a central control unit of the domestic refrigeration appliance takes over the functions of measuring and evaluating the motor current and controlling the operation of the electric motor 24.