Abstract: A linear electro-mechanical actuator comprises a housing with a reversible DC-motor (1), which through a transmission (2) can move an activation element (5) between two end positions. The activation element (5) will in the two end positions cause the electrical end stop switches (17, 25) to be activated for interrupting the current for the DC motor (1) in the end positions of the activation element (5) for running the motor (1) in one direction. Parallel to the end stop switches (17, 25), an extra set of switches (21, 23) are incorporated for determining in which end position the activation element (5) is located.

Abstract: A linear actuator includes a spindle nut, where the spindle nut and the spindle between a first and a second point, indicating the length of stroke, can move axially in proportion to each other, depending on whether the spindle or the spindle nut is being driven around via the transmission, and where the position is determined with incremental position sensors, such as at least two Hall sensors or Reed-switches. For determining the position an initiating procedure, where the nut/spindle is moved from a first point on the spindle/nut to a second point on the spindle nut is carried out, and that the number of pulses from the incremental position sensors appearing by it are registered as a measurement for the length of stroke, and the position is subsequently determined in relation to that. It is noted that the control is active before, during and after the operation of the motor.

Abstract: A linear electro-mechanical actuator comprises a housing with a reversible DC-motor (1), which through a transmission (2) can move an activation element (5) between two end positions. The activation element (5) will in the two end positions cause the electrical end stop switches (17, 25) to be activated for interrupting the current for the DC motor (1) in the end positions of the activation element (5) for running the motor (1) in one direction. Parallel to the end stop switches (17, 25), an extra set of switches (21, 23) are incorporated for determining in which end position the activation element (5) is located.

Abstract: In particular in articles of furniture having at least an element which may be adjusted with a DC motor, preferably via a mechanical transmission, it is desirable to have a level of acoustic noise as low as possible. The power supply to the DC motor is based on a transformer with rectification and smoothing. With the invention it has surprisingly been found that the level of acoustic noise may be reduced significantly in that the secondary side of the transformer has a first control to compensate for the loss in the motor, thereby keeping the speed thereof constant for a long period of time, and a second control adapted to remove the ripple in the voltage, thereby keeping the speed of the motor constant for a short period of time.

Abstract: A linear actuator comprising a spindle nut, where the spindle nut and the spindle between a first and a second point, indicating the length of stroke, can move axially in proportion to each other, depending on whether the spindle or the spindle nut is being driven around via the transmission, and where the position is determined with incremental position sensors, such as at least two Hall sensors or Reed-switches. For determining the position an initiating procedure, where the nut/spindle is moved from a first point on the spindle/nut to a second point on the spindle nut, is carried out, and that the number of pulses from the incremental position sensors appearing by it are registered as a measurement for the length of stroke, and the position is subsequently determined in relation to that. It is noted that the control is active before, during and after the operation of the motor.

Abstract: In adjustable structure with a drive unit (8), e.g., an actuator driven by an electric motor and controlled via a control unit, a jamming protection arrangement is needed in certain connections. A solution is provided to a jamming protection arrangement, based on a piezo element (20) incorporated in the structure, alternatively in the drive unit. The piezo element is connected with the control unit, which is constructed such that the drive unit is stopped or reversed if a deviation occurs in the force on the adjustable element (5) or the structure.

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: In particular in articles of furniture having at least an element which may be adjusted with a DC motor, preferably via a mechanical transmission, it is desirable to have a level of acoustic noise as low as possible. The power supply to the DC motor is based on a transformer with rectification and smoothing. With the invention it has surprisingly been found that the level of acoustic noise may be reduced significantly in that the secondary side of the transformer has a first control to compensate for the loss in the motor, thereby keeping the speed thereof constant for a long period of time, and a second control adapted to remove the ripple in the voltage, thereby keeping the speed of the motor constant for a short period of time.

Abstract: In adjustable structure with a drive unit (8), e.g., an actuator driven by an electric motor and controlled via a control unit, a jamming protection arrangement is needed in certain connections. A solution is provided to a jamming protection arrangement, based on a piezo element (20) incorporated in the structure, alternatively in the drive unit. The piezo element is connected with the control unit, which is constructed such that the drive unit is stopped or reversed if a deviation occurs in the force on the adjustable element (5) or the structure.

Abstract: A control for DC motors, in particular actuators driven by a DC motor for adjustment of furniture, such as tables, beds, chairs, etc. includes a pseudomotor which is capable of supplying a voltage that corresponds to the motor speed on the basis of the current and voltage supplied to the motor. The voltage of the pseudomotor is supplied to an adjustable power supply, where it is compared with an internal reference voltage and adjusts the voltage difference down to the smallest possible difference between the voltage of the pseudomotor and the internal reference voltage. For greater accuracy, the control additionally includes a compensation circuit configured to evaluate a dominating frequency in the commutator noise. Thus, there is provided a simple and low cost control for parallel running of two or more actuators.

Abstract: A control for DC motors, in particular actuators driven by a DC motor for adjustment of furniture, such as tables, beds, chairs, etc. inlcudes a pseudomotor which is capable of supplying a voltage that corresponds to the motor speed on the basis of the current and voltage supplied to the motor. The voltage of the pseudomotor is supplied to an adjustable power supply, where it is compared with an internal reference voltage and adjusts the voltage difference down to the smallest possible difference between the voltage of the pseudomotor and the internal reference voltage. For greater accuracy, the control additionally includes a compensation circuit configured to evaluate a dominating frequency in the commutator noise. Thus, there is provided a simple and low cost control for parallel running of two or more actuators.