Method and Apparatus for Reversing a Piston Rod in an Injection Device
First Claim
1. A method for reversing a piston rod in an injection device, the piston rod being operatively connected to a motor shaft of an electrical motor so that a rotational movement of the motor shaft is transformed to a translational movement of the piston rod, the piston rod being adapted to be moved between two end positions, the method comprising:
- providing a first supply voltage level to the electrical motor,measuring sets of corresponding values of current provided to the motor and piston rod position,shutting down the electrical motor in case the measured current provided to the motor exceeds a predetermined value, andcomparing a measured final position of the piston rod with a predetermined position range.
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Abstract
The present invention relates to a method for moving a piston rod in an injection device, the piston rod being operatively connected to a motor shaft of an electrical motor so that a rotational movement of the motor shaft is transformed to a translational movement of the piston rod, the piston rod being adapted to be moved between two end positions, the method comprising the steps of providing a first supply voltage level to the electrical motor, measuring sets of corresponding values of current provided to the motor and a corresponding position of the piston rod, and providing a second supply voltage level to the electrical motor when the measured position of the piston rod equals predetermined positions, the second supply voltage level having a RMS value being smaller than the RMS value of the first supply voltage level. The present invention further relates to an apparatus for carrying out the method.
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Citations
14 Claims
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1. A method for reversing a piston rod in an injection device, the piston rod being operatively connected to a motor shaft of an electrical motor so that a rotational movement of the motor shaft is transformed to a translational movement of the piston rod, the piston rod being adapted to be moved between two end positions, the method comprising:
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providing a first supply voltage level to the electrical motor, measuring sets of corresponding values of current provided to the motor and piston rod position, shutting down the electrical motor in case the measured current provided to the motor exceeds a predetermined value, and comparing a measured final position of the piston rod with a predetermined position range. - View Dependent Claims (2, 3, 4, 5)
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6. A method for reversing a piston rod in an injection device, the piston rod being operatively connected to a motor shaft of an electrical motor so that a rotational movement of the motor shaft is transformed to a translational movement of the piston rod, the piston rod being adapted to be moved between two end positions, the method comprising:
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providing a first supply voltage level to the electrical motor, measuring sets of corresponding values of current provided to the motor and piston rod position, and providing a second supply voltage level to the electrical motor in case the measured position of the piston rod equals predetermined positions, the second supply voltage level having a RMS value being smaller than the RMS value of the first supply voltage level. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. An apparatus for reversing a piston rod in an injection device, the piston rod being operatively connected to a motor shaft of an electrical motor so that a rotational movement of the motor shaft is transformed to a translational movement of the piston rod, the piston rod being adapted to be moved between two end positions, the apparatus comprising:
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means for providing a first supply voltage level to the electrical motor, means for measuring sets of corresponding values of current provided to the motor and piston rod position, and means for shutting down the electrical motor in case the measured current provided to the motor exceeds a predetermined value.
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14. An apparatus for reversing a piston rod in an injection device, the piston rod being operatively connected to a motor shaft of an electrical motor so that a rotational movement of the motor shaft is transformed to a translational movement of the piston rod, the piston rod being adapted to be moved between two end positions, the apparatus comprising:
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means for providing a first supply voltage level to the electrical motor, means for measuring sets of corresponding values of current provided to the motor and piston rod position, and means for providing a second supply voltage level to the electrical motor if the measured position of the piston rod equals predetermined positions, the second supply voltage level having a RMS value being smaller than the RMS value of the first supply voltage level.
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Specification