Abstract: A linear actuator (1) comprises a spindle nut arranged to be moved between two end positions on a spindle driven by a DC motor (2). An end stop switch (31) is arranged to be activated when the spindle nut is in an end position. In its activated state, the end stop switch disconnects the motor current and connects a first diode (33) across the DC motor for short circuiting the motor when the current is interrupted. A second diode (32) is connected over the end stop switch for enabling the DC motor to drive the spindle nut out of said end position. An additional component (43) in series with the first diode reduces noise problems caused by motor current circulating through this diode during pulse pauses while the spindle nut is driven out of an end position by a pulse width modulated voltage via a cable from a control box.

Abstract: A linear actuator comprises a brushless DC motor (31), a driver circuit (51) for providing a multiphase voltage signal to the motor (31) and a controller (58) for detecting a rotor position and providing control signals to the driver circuit (51) in dependence thereof. Detector circuitry (61) detects a signal indicative of rotor speed. The controller (58) is configured to control the driver circuit (51) to drive the motor with a first waveform of the multiphase voltage signal, when the indicative signal indicates that the rotor speed does not exceed a predetermined speed; and control the driver circuit (51) to drive the motor with a second waveform of the multiphase voltage signal, when the indicative signal indicates that the rotor speed exceeds the predetermined speed, wherein the second waveform is selected to drive the motor (31) with an efficiency less than the efficiency when driven by the first waveform.

Abstract: An electrical current flowing in a selected one of a plurality of electric motors (51, 52, 53) connected to and supplied from a power supply, wherein a current measuring device (46) is arranged in a connection between the power supply and the plurality of electric motors, is determined. Non-selected electric motors are controlled to be temporarily disconnected from the power supply, and then a current measurement is performed by the current measuring device, while the non-selected electric motors are temporarily disconnected from the power supply. Thus, this current measurement is indicative of the electrical current flowing in the selected electric motor. When the current measurement has been performed, the non-selected electric motors are again controlled to be reconnected to the power supply. In this way, the current drawn by individual motors can be determined with the use of only one current measuring device, so that additional costs can be avoided.

Abstract: A linear actuator (1) comprises a spindle nut arranged to be moved between two end positions on a spindle driven by a DC motor (2). An end stop switch (31) is arranged to be activated when the spindle nut is in an end position. In its activated state, the end stop switch disconnects the motor current and connects a first diode (33) across the DC motor for short circuiting the motor when the current is interrupted. A second diode (32) is connected over the end stop switch for enabling the DC motor to drive the spindle nut out of said end position. An additional component (43) in series with the first diode reduces noise problems caused by motor current circulating through this diode during pulse pauses while the spindle nut is driven out of an end position by a pulse width modulated voltage via a cable from a control box.

Abstract: A flyback converter (21) for use in a power supply for an electric actuator system comprises a snubber circuit with a snubber capacitor (23) for accumulating energy stored in a leakage inductance of a flyback transformer (4) when a primary current (Iprim) is switched off. The snubber circuit further comprises a controllable switching element (24) in series with the snubber capacitor (23) with a control terminal connected to a voltage reference. The controllable switching element (24) can be in a conducting mode when the snubber capacitor voltage exceeds the reference voltage. In this way, the leakage inductance energy can be transferred to the secondary side instead of being dissipated in a resistor in the snubber circuit. This increases the power efficiency of the converter and reduces electromagnetic interference. At the same time, the solution is very simple and can thus be implemented at a low cost.

Abstract: A linear actuator comprises a brushless DC motor (31), a driver circuit (51) for providing a multiphase voltage signal to the motor (31) and a controller (58) for detecting a rotor position and providing control signals to the driver circuit (51) in dependence thereof. Detector circuitry (61) detects a signal indicative of rotor speed. The controller (58) is configured to control the driver circuit (51) to drive the motor with a first waveform of the multiphase voltage signal, when the indicative signal indicates that the rotor speed does not exceed a predetermined speed; and control the driver circuit (51) to drive the motor with a second waveform of the multiphase voltage signal, when the indicative signal indicates that the rotor speed exceeds the predetermined speed, wherein the second waveform is selected to drive the motor (31) with an efficiency less than the efficiency when driven by the first waveform.

Abstract: A flyback converter (21) for use in a power supply for an electric actuator system comprises a snubber circuit with a snubber capacitor (23) for accumulating energy stored in a leakage inductance of a flyback transformer (4) when a primary current (Iprim) is switched off. The snubber circuit further comprises a controllable switching element (24) in series with the snubber capacitor (23) with a control terminal connected to a voltage reference. The controllable switching element (24) can be in a conducting mode when the snubber capacitor voltage exceeds the reference voltage. In this way, the leakage inductance energy can be transferred to the secondary side instead of being dissipated in a resistor in the snubber circuit. This increases the power efficiency of the converter and reduces electromagnetic interference. At the same time, the solution is very simple and can thus be implemented at a low cost.

Abstract: A power converter for converting power from a first voltage level at an input terminal to a second voltage level across first and second output terminals, the power converter including a first inductor having one end connected to the input terminal and another end connected to a point with a switched voltage level, a first switch element with a first terminal connected to the point and a second terminal connected to ground and a second switch element connected in series with a capacitor through a first terminal, and a second terminal of the second switch element being connected to the point and the capacitor being terminated to ground, the first switch element being operated with a first duty cycle (D), and wherein the second switch element being operated with a second duty cycle (1-D), wherein the first and second switch elements are operated such that their conducting periods are complementary, wherein the switched voltage level at the point includes a first pulse generated when the first switch element con

Abstract: Actuator system comprising at least one electrically driven linear actuator with an electric motor and an electric controller with an operating unit, wherein the electric motor is furnished with means for electrical noise dampening of the motor, which comprises a first inductance and a second inductance for electrical noise dampening of the motor, said first and second inductance are physically wound on the same coil form and thus provides a more compact construction, which moreover reduces the costs.

Abstract: A linear actuator system comprising at least one linear actuator, a power supply, a control and an operation device. The linear actuator system comprises at least one printed circuit board having multiple layers comprising an electrically conductive circuit. At least one of the layers of the printed circuit board is designed as a detection layer for detecting a leakage current in the electrical circuit, including the electronic components mounted on the printed circuit board. An output voltage is applied to the detection layer, said voltage falling outside of the voltage range in which the electrical circuit works.

Abstract: A linear actuator with a reversible electric motor (3,11,26,27,34), which over a transmission (4,12,24,25,35) drives a non-self locking spindle (5,14,22,23,36), by which a tube-shaped positioning element can be moved axially, in that it with one end is connected to a spindle nut (6,15) on a spindle (5,14,22,23,36). The actuator comprises a quick release (9,13) for releasing the tube-shaped positioning element (7,16,28,29,37) from the electric motor (3,11,26,27,34) and the part of the transmission (4,12,24,25,35) that lies from the motor (3,11,26,27,34) to the quick release (9,13) such that the spindle (5,14,22,23,36) is set to rotate by the load on the tube-shaped positioning element (7,16,28,29,37). The actuator further comprises braking means for controlling the speed of the tube-shaped positioning element (7,16,28,29,37) during the outer load, when the quick release (9,13) is activated.

Abstract: The present invention relates to a power converter for converting power from a first voltage level at an input terminal to a second voltage level across an first and second output terminals, the power converter comprising, a first inductor, with one end connected to the input terminal and another end connected to a point with a switched voltage level, a first switch element with a first terminal connected to the point and a second terminal connected to ground and a second switch element connected in series with a capacitor through a first terminal, and a second terminal of the second switch element being connected to the point and the capacitor being terminated to ground, the first switch element is arranged for being operated with a first duty cycle (D), and wherein the second switch element is arranged for being operated with a second duty cycle (1-D), wherein the first and second switch elements are arranged to operated such that their conducting periods are complementary, wherein the switched voltage leve

Abstract: A linear actuator system comprising at least one linear actuator, a power supply, a control and an operation device. The linear actuator system comprises at least one printed circuit board having multiple layers comprising an electrically conductive circuit. At least one of the layers of the printed circuit board is designed as a detection layer for detecting a leakage current in the electrical circuit, including the electronic components mounted on the printed circuit board. An output voltage is applied to the detection layer, said voltage falling outside of the voltage range in which the electrical circuit works.

Abstract: A linear actuator with a reversible electric motor (3,11,26,27,34), which over a transmission (4,12,24,25,35) drives a non-self locking spindle (5,14,22,23,36), by which a tube-shaped positioning element can be moved axially, in that it with one end is connected to a spindle nut (6,15) on a spindle (5,14,22,23,36). The actuator comprises a quick release (9,13) for releasing the tube-shaped positioning element (7,16,28,29,37) from the electric motor (3,11,26,27,34) and the part of the transmission (4,12,24,25,35) that lies from the motor (3,11,26,27,34) to the quick release (9,13) such that the spindle (5,14,22,23,36) is set to rotate by the load on the tube-shaped positioning element (7,16,28,29,37). The actuator further comprises braking means for controlling the speed of the tube-shaped positioning element (7,16,28,29,37) during the outer load, when the quick release (9,13) is activated.

Abstract: An actuator system, preferably for patient lifters, includes at least one actuator driven by an electric motor, a control unit having a power limiting circuit, and at least one handset having a plurality of keys. The actuator system is arranged such that the threshold value of the maximum permissible power in the power limiting circuit may be changed, and that this change may be performed via a key on the handset. Thus, it is possible to subsequently adjust the cutout limit safely and easily via a key on a handset, so that the cutout limit may be adapted to the actual application into which the actuator system is to be incorporated. For reasons of safety, it is preferred to use a separate handset for changing the threshold value.

Abstract: An actuator system, preferably for patient lifters, comprises at least one actuator (4) driven by an electric motor, a control unit having a power limiting circuit, and at least one handset having a plurality of keys. The actuator system is arranged such that the threshold value of the maximum permissible power in the power limiting circuit may be changed, and that this change may be performed via a key (9) on the handset. Thus, it is possible to subsequently adjust the cutout limit safely and easily via a key on a handset, so that the cutout limit may be adapted to the actual application into which the actuator system is to be incorporated. For reasons of safety, it is preferred to use a separate handset for changing the threshold value.

Abstract: An actuator, preferably a linear actuator for furniture, comprises a brake spring (20) in the form of a helical spring having a plurality of windings wound around a cylindrical element (10) of plastics rotatable at least during braking, said spring being tightened around the cylindrical element for braking. The frictional heat generated hereby can cause the plastics to be deformed, which adversely affects the braking power. This is solved by providing the cylindrical element (10) consisting of plastics with an insert (12) of metal for carrying off the frictional heat preferably into other metal parts of the actuator that may serve as cooling faces. To carry off heat additionally, it is proposed to arrange a second heat-conducting element (18) in intimate contact with the outer side of the spring (20), said element being likewise connected with other metal parts of the actuator that may serve as cooling faces.

Abstract: A remote control system includes at least one hand control (2) and one or more control units (4). Each control units transmits a signal with a unique frequency. The hand control receives this signal from the control unit, which appears the strongest to the hand control receiver, as well as transmits a signal with a frequency which is a whole multiple of the received signal. The advantage of the system is that an arbitrary hand control automatically adapts itself to the control unit from which the signal is strongest and subsequently communicates with the control unit. The system may be constructed such that one-way or two-way communication may take place. In one embodiment, the system is exclusively composed of standard components, the spreading on the components being used for forming the unique signal. The system lends itself for all forms of furniture equipped with motor driven adjustment facilities.

Abstract: A power supply for DC motors, in particular for actuators for use in the adjustment of tables, beds and the like, comprises a transformer (T1) with a rectifier (D1-D4) and a buffer capacitor. The power supply comprises voltage limiting means (Z1) coupled in parallel with the motor and connected to switch means (Q1) so that the motor is connected on a first part of the sine half-waves, but is disconnected when the voltage determined for the voltage limiter is reached. This ensures a good mean voltage, and the voltage does not exceed an upper permissible value. This also means that the motor speed is more independent of the load, which is an advantage e.g. in case of height-adjustable tables.

Abstract: A power supply for DC motors, in particular for actuators for use in the adjustment of tables, beds and the like, comprises a transformer (T1) with a rectifier (D1-D4); and a buffer capacitor. The power supply comprises voltage limiting unit (Z1) coupled in parallel with the motor and connected to switch unit (Q1) so that the motor is connected on a first part of the sine half-waves, but is disconnected when the voltage determined for the voltage limiter is reached. This ensures a good mean voltage, and the voltage does not exceed an upper permissible value. This also means that the motor speed is more independent of the load, which is an advantage e.g. in case of height-adjustable tables. In an embodiment, the power supply comprises additional means for measuring the current power in the motor, and this measurement is used as a feedback for controlling the motor speed to keep the speed of the motor.