Electromotive furniture drive for a piece of furniture, a method for monitoring a pulse-width ratio of an electromotive furniture drive, and a corresponding piece of furniture

Patent metadata

Field	Value
Publication number	US-9713387-B2
Application number	US-201314381843-A
Country	US
Kind code	B2
Filing date	Feb 28, 2013
Priority date	Feb 28, 2012
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

The invention relates to an electromotive furniture drive ( 100 ) for adjusting a movable part ( 4, 5 ) of a piece of furniture ( 1 ) by means of an output element, comprising a) at least one adjusting drive ( 7, 8 ) with respectively at least one electric motor, a speed reducing mechanism which is coupled thereto and which ensures that the output element is drivenly coupled and can be linearly displaced and/or rotatably moved, and when said output element reaches a predetermined position, said output element actuates an end switch and/or reference switch and/or switching means, b) at least one control device ( 9 ) and c) at least one control unit ( 10 ), said control device ( 9 ) comprising a positioning device for the output element provided with a control block with a counter and a recording device for evaluating impulses of a counter EMK of the at least one electric motor. Said control device ( 9 ) comprises a digital potentiometer which emits as an output value, an electric value which is proportionate to the position of said output element. The control device comprises, in a further embodiment, a monitoring device. The invention also relates to a method for monitoring a pulse width ratio of an electromotive furniture drive and a piece of furniture ( 1 ).

First claim

The invention claimed is:

1. An electromotive furniture drive for adjusting a movable part of a piece of furniture, said electromotive furniture drive comprising:
an output element;
at least one adjusting drive including at least one electric motor and a revolution speed reducing gear mechanism coupled to the at least one electric motor, said revolution speed reducing gear mechanism being coupled in driving relationship to the output element to linearly displace and/or rotatably move the output element, wherein the output element, upon reaching a predetermined position, actuates at least one member selected from the group consisting of an end switch, a reference switch, and a switching unit;
at least one control device comprising a positioning apparatus which is configured to position the output element, said positioning apparatus including a control block having a counter and a memory device for evaluating pulses of a back-EMF of the at least one electric motor;
at least one operating unit operatively connected to the at least one control device to operate the at least one adjusting drive; and
at least one monitoring apparatus configured to monitor a pulse-width ratio of a detected back-EMF of the at least one electric motor, said at least one monitoring apparatus comprising at least one filter unit with a pulse former and a load monitoring device with a pulse-width ratio detector, a comparator, and a signal generator, said pulse width ratio detector being configured to detect the pulse-width ratio of the detected back-EMF of the at least one electric motor, said comparator comparing the detected pulse width ratio with a predetermined value and causing the signal generator to generate a signal for control of the at feast one electric motor for throttling the at least one electric motor.

2. The electromotive furniture drive of claim 1 , wherein the pulse former is a square-wave pulse former.

3. The electromotive furniture drive of claim 1 , wherein the comparator is configured to compare the detected pulse-width ratio with a previously determinable value.

4. The electromotive furniture drive of claim 3 , wherein the previously determinable value corresponds to a pulse-width ratio of 10/90.

5. The electromotive furniture drive of claim 1 , wherein the signal generator is configured to generate a signal for control of the at least one electric motor for throttling the at least one electric motor.

6. The electromotive furniture drive of claim 1 , wherein the monitoring apparatus comprises at least one return-motion monitoring device coupled to an output of the filter unit.

7. The electromotive furniture drive of claim 6 , wherein the return-motion monitoring device is configured to recognize a rotation of a motor shaft of the at least one electric motor in a short-circuited and deactivated state of the at least one electric motor and for signaling such recognition.

8. The electromotive furniture drive of claim 1 , further comprising at least one energy storage unit connected to the monitoring apparatus.

9. The electromotive furniture drive of claim 8 , wherein the at least one energy storage unit is a rechargeable battery or a capacitor of high capacitance.

10. The electromotive furniture drive of claim 8 , wherein the at least one energy storage unit has a storage capacity sized to operate part of an electric circuit of the positioning apparatus for detecting, evaluating and counting ripples in a currentless state at least for a specific time interval via the energy storage unit.

11. The electromotive furniture drive of claim 1 , wherein the control device comprises a digital potentiometer configured to output an electric value as an output value which is proportional to a position of the output element.

12. The electromotive furniture drive of claim 11 , wherein the digital potentiometer comprises at least one buffer memory unit provided for intermediate storage of counts of the counter, and at least one digital-to-analog converter configured to convert a count which is intermediately stored in the buffer memory unit into an analog output value.

13. The electromotive furniture drive of claim 12 , wherein the analog output value converted by the digital-to-analog converter is a voltage value and/or a current value.

14. The electromotive furniture drive of claim 12 , wherein the analog output value converted by the digital-to-analog converter lies within a predetermined voltage or current interval, wherein a minimum value corresponds to a first end position state of the output element and a maximum value corresponds to a second end position state of the output element.

15. The electromotive furniture drive of claim 12 , wherein the buffer memory unit is configured as a rewritable volatile or non-volatile memory.

16. The electromotive furniture drive of claim 1 , wherein at least one end switch, upon actuation in an end position of the output element, is provided for controlling an interruption in a power supply to the at least one electric motor, for controlling a short-circuiting of the at least one electric motor and for controlling a new setting of a reference point for control or positioning of the output element.

17. The electromotive furniture drive of claim 1 , wherein at least one end switch is arranged at a previously determined location and is provided for controlling a new setting of a reference point for control or positioning of the output element.

18. The electromotive furniture drive of claim 1 , wherein the at least one electric motor is configured for soft start-up with at least one bridgeable series resistor.

19. A method for monitoring a pulse-width ratio of an electromotive furniture drive, comprising the steps of:
detecting pulses of a back-EMF of at least one electric motor of the electromotive furniture drive by measuring a voltage drop in a resistor or a specific resistance of a transistor;
detecting a pulse-width ratio of ripples of the detected back-EMF of the at least one electric motor;
comparing the detected pulse-width ratio with a previously determinable value; and
monitoring the detected pulse-width ratio by evaluating the comparing step.

20. The method of claim 19 , further comprising converting the detected pulses of the back-EMF of the at least one electric motor into square-wave pulses.

21. The method of claim 19 , wherein the previously determinable value for the comparing step corresponds to a pulse-width ratio of 10/90.

22. The method of claim 19 , wherein the monitoring step includes a throttling of the at least one electric motor in operation, when a value drops below a critical comparative value.

23. The method of claim 19 , wherein the comparing step includes monitoring a frequency of the ripples, and the monitoring step includes generating a signal in the presence of a jamming or an overload.

24. A piece of furniture, comprising:
at least one base element configured to couple the piece of furniture to an installation site,
at least one support element having a part which is movably arranged relative to the support element or relative to a further support element or relative to the at least one base element, said at least one movably arranged part being constructed to be displaceable and/or pivotable, and
at least one electromechanical furniture drive coupled to the at least one movably arranged part and comprising an output element, at least one adjusting drive including at least one electric motor

Assignees

• Dewertokin Gmbh

Inventors

• Hille Armin

Classifications

• A47C20/041 Primary

  by electric motors · CPC title

• A47C31/008

  Use of remote controls · CPC title

• A47C17/04 Primary

  {Seating furniture, e.g.} sofas, couches, settees, or the like, with movable parts {changeable to beds}; Chair beds · CPC title

• A47C17/86

  Parts or details specially adapted for beds, sofas or couches not fully covered by any single one of groups A47C17/02 - A47C17/84 · CPC title

• A47C7/62

  Accessories for chairs · CPC title