Patent Application
20090320627
1. Field of the Invention
The invention is directed to a driving device, particularly for a hatch in a vehicle, with a first fastening element which can be connected to a stationary structural component part or to a movable structural component part, and with a housing tube which is movable axially relative to the first fastening element and can be fastened to the other component part. A spindle drive has a spindle nut arranged on a threaded spindle, by which the first fastening element and the housing tube are drivable so as to be movable axially relative to one another between a moved out position and a moved in position, wherein the spindle drive is rotatably drivable by an electric motor drive which is arranged in the housing tube and which is controllable by a control unit having a power output stage.
2. Description of the Related Art
In a driving device of the type mentioned above, it is known to arrange the control unit at a distance from the driving device and to connect it to the driving device by a feed line.
High actuating forces are required particularly in the initial range of the outward stroke which lead to high currents in the feed line. These high currents generate a substantial EMC load which, particularly when the driving device is used in motor vehicles, can lead to problems in the other electrical and electronic equipment in the motor vehicle.
It is an object of the invention to provide a driving device of the type mentioned above which prevents EMC loads of this kind particularly in the initial range of the outward stroke of the driving device.
According to the invention, this object is met by a power supply to the electric motor drive which includes a power output stage arranged in the housing tube and shielded from electrical and/or magnetic fields.
Since the power output stage is now arranged near the electric motor drive and is also well-shielded, EMC loads emanating from the driving device are prevented at least substantially and the feed line resistance to the electric drive unit is kept low. Uneconomical shielding of the feed lines is not required.
Further, the power supply can include an electric energy storage arranged in the housing tube and/or by an electric voltage amplifier (booster). As a result, the energy storage is switched on in the initial range of the outward stroke and provides temporary high power. Voltage is likewise made available to the electric motor by the electric voltage amplifier by way of the vehicle power supply, which ensures a higher starting torque of the electric motor drive arranged downstream.
Accordingly, the structural dimensions of the driving device can also be kept small through the use of a low-power, compact electric motor drive. However, the electric motor drive can be loaded beyond its nominal rating for short periods of time without being damaged. Blocking currents occurring at the start of the outward stroke are compensated simultaneously and do not lead to a significant loading of the vehicle power supply. There is also a compensation of voltage losses in the feed lines.
When the housing is constructed from a material with high electrical conductivity, particularly a soft-magnetic material, no special shielding elements are required.
When the power output stage and/or the electric voltage amplifier and/or the electric energy storage are/is arranged in series with the electric motor drive, this results in a compact construction and, therefore, small structural dimensions of the driving device.
The power output stage is preferably a pulse width modulation power output stage so that an analog electric motor drive can also be controlled by digital pulses. The power output stage can also be an inverter by means of which a brushless motor can be driven.
The electrical energy storage can be a battery or a capacitor. When the electric energy storage is a double-layer capacitor (supercapacitor), especially high capacitances are additionally available for the initial range of the outward stroke.
To achieve a temporary increase in power of the electric motor drive, the electromotor voltage amplifier can be a DC-DC converter, a diode cascade or a transformer. The diode cascade has the advantage that it generates only low switching losses and can be implemented in a small space.
Further, in a space-saving manner, the rate of rotation and/or rotating direction of the output shaft of the electric motor drive can be acquired by a sensor arrangement, and a corresponding signal can be supplied to the power output stage.
To reduce speed and increase torque, the spindle drive can be rotatably driven by the electromotor rotary drive by means of a gear unit.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
The driving device shown in the drawings has a housing tube 1 at which an outer tube 2 is guided so as to be displaceable in a telescoping manner.
A first ball socket 3 is arranged at the end of the outer tube 2 located opposite to the housing tube 1, and a second ball socket 4 is arranged at the end of the housing tube 1 located opposite to the outer tube 2. The driving device can be connected in an articulated manner to a stationary structural component part of the body of a motor vehicle and to a movable structural component part of the motor vehicle constructed as a hatch by means of the first and second ball sockets 3 and 4.
A bearing 5 is fixedly installed in the end area of the housing tube facing the outer tube 2, one end of a threaded spindle 6 projecting coaxially into the outer tube 2 being rotatably supported at this bearing 5. The threaded spindle 6 is supported axially by means of the bearing 5.
A spindle nut 7 is arranged on the threaded spindle 6 so as to be fixed with respect to rotation relative to the housing tube 1. The spindle nut 7 is connected to one end of a spindle tube 8 which surrounds the threaded spindle 6 coaxially, the first ball socket 3 being fixedly arranged at its other end. The spindle nut 7 is guided in an axially displaceable manner in a guide tube 9 surrounding the spindle tube 8, this guide tube 9 being fixedly connected to the housing tube 1.
A helical compression spring 10 is arranged in the annular gap between the guide tube 9 and the outer tube 2 surrounding the latter at a distance radially and is supported axially by one end at the outer tube 2 in the area of the first ball socket 3 and by its other end at the housing tube 1.
The threaded spindle 6 has a guide sleeve 11 at its end facing the first ball socket 3 and is guided by its cylindrical outer surface so as to be axially displaceable in the spindle tube 8.
The guide tube 9 has axial slots 12 extending substantially along its length. Corresponding to the axial slots 12, radially projecting supporting pins 13 are arranged at the spindle nut 7 and project into the axial slots 12 radially so as to ensure that the spindle nut 7 is fixed with respect to rotation relative to the guide tube 9.
A driven shaft 14 of a gear unit 15 is connected coaxially to the threaded spindle 6 so as to be fixed with respect to rotation relative to it. The gear unit 15 can be driven rotatably by means of the output shaft 17 of an electric motor 16. The output shaft 17 also projects out of the electric motor 16 on the side remote of the gear unit 15 and has at its free end a permanent magnet 18 which is located axially opposite to a sensor board 20 of a rate of rotation and rotating direction sensor arrangement 28, this sensor board 20 being arranged in a stationary manner and having a Hall element 19.
On the side of the electric motor 16 facing the second ball socket 4 following the rate of rotation and rotating direction sensor arrangement, a control unit 21 with a pulse width modulation power output stage or an inverter power output stage, an electric voltage amplifier 22, and an electric energy storage 23 are arranged coaxial to the electric motor 16 in the housing tube 1, which is made of a soft-magnetic material. The closing cover 24 of the housing tube 1 carrying the second ball socket 4 is likewise made of a soft-magnetic material so that the components located in the housing tube 1 are shielded outwardly against electrical and magnetic fields.
A feed line 26 is guided through an opening 25 of the closing cover 24 and connects the energy storage 23, the voltage amplifier 22, the control unit 21 and the electric motor 16 to a power source, in particular a car battery.
The block diagram shown in
In order to supply the electric motor 16 with a voltage higher than the vehicle power supply voltage of 12 V, the DC voltage of 12 V which is provided by a battery is increased, for example, to 24 V in a voltage amplifier constructed as a DC-DC converter 30 and is supplied to the electric motor 16 either directly or by means of an energy storage 23 and the pulse width modulation power output stage 29.
The invention is not limited by the embodiments described above which are presented as examples only but can be modified in various ways within the scope of protection defined by the appended patent claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 030 247.3 | Jun 2008 | DE | national |
