Jamming protection device for moving member
First Claim
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1. A jamming protection device for a moving member driven by a motor (5), wherein the motor (5) is able to rotate in reverse directions and is supplied with a motor current (ID) by a power supply unit (VB), the jamming protection device comprising:
- a current detection circuit (2) being connectable to one of a plus terminal and a minus terminal of the power supply unit (VB), configured to conduct the motor current (ID) and to detect an increment of the motor current (ID) as a result of a jamming event; and
a current limiting circuit (7) configured to conduct the motor current (ID) start a current limiting operation in which the motor current (ID) is decreased and increased within a predetermined region when the increment of the motor current (ID) exceeds a predetermined value.
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Abstract
When abnormal current due to jamming is detected through motor current (ID), the motor current (ID) performs an operation in which an ON/OFF operation and a continuous ON operation are repeated, so that increment of the motor current (ID) is restrained. At this time, determination of jamming is performed based on the ON/OFF operation and the continuous ON operation. When the jamming is determined, the motor current (ID) is stopped, and the motor is reversed.
38 Citations
27 Claims
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1. A jamming protection device for a moving member driven by a motor (5), wherein the motor (5) is able to rotate in reverse directions and is supplied with a motor current (ID) by a power supply unit (VB), the jamming protection device comprising:
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a current detection circuit (2) being connectable to one of a plus terminal and a minus terminal of the power supply unit (VB), configured to conduct the motor current (ID) and to detect an increment of the motor current (ID) as a result of a jamming event; and
a current limiting circuit (7) configured to conduct the motor current (ID) start a current limiting operation in which the motor current (ID) is decreased and increased within a predetermined region when the increment of the motor current (ID) exceeds a predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A jamming protection device for a moving member driven by a motor (5), wherein the motor (5) is able to rotate in reverse directions and is supplied with a motor current (ID) by a power supply unit (VB), the jamming protection device comprising:
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a current detection circuit (2) being connectable to one of a plus terminal and a minus terminal of the power supply unit (VB), configured to conduct the motor current (ID) and to detect an increment of the motor current (ID) as a result of a jamming event, comprising a main element (R1, T4) having a main resistance configured to conduct the motor current (ID), a reference element (R20, T5) having a reference resistance configured to conduct a reference current (Iref), the reference resistance being n times as much as the main resistance, and a current following circuit (14) coupled to both the main element (R1, T4) and the reference element (R20, T5) to conduct the reference current (Iref) and to set the reference current (Iref) at one over n (1/n) of the motor current (ID) constantly, including a comparator (CMP1) configured to detect a difference between voltage drops across the main element (R1, T4) and the reference element (R20, T5), a slow following circuit (42 and 45), including a slow charge discharge circuit (45) coupled to an output of the comparator (CMP1) and the ground, the slow charge discharge circuit (45) including a first resistor (R21) coupled to the output of the comparator (CMP1) and a capacitor (C1) coupled in series to the first resistor (R21) and to the ground, and a slow source follower circuit (42) including a first field effect transistor (T21) and a second resistor (R23) coupled to a source of the first field effect transistor (T21), a gate of the first field effect transistor (T21) being coupled to the capacitor (C1) and a drain of the first field effect transistor (T21) being coupled to one of the plus terminal and minus terminal of the power supply unit (VB), and a fast following circuit (44) coupled in parallel to the slow following circuit (42 and 45), the fast following circuit (44) including a second field effect transistor (T22) and a third resistor (R24) configured to conduct a fast following current (Iref-f), a gate of the second field effect transistor (T22) being coupled to the output of the comparator (CMP1);
and a current limiting circuit (7) configured to conduct the motor current (ID) and to start a current limiting operation in which the motor current (ID) is decreased and increased within a predetermined region when the increment of the motor current (ID) exceeds a predetermined value, including a semiconductor-switching element (T1), wherein the motor current (ID) is decreased by an ON/OFF operation of the semiconductor switching element (T1)-for a period that depends on a reduction of the motor speed due to the jamming, and the motor current (ID) is increased by a continuous ON operation of the semiconductor switching element (T1), wherein the motor current (ID) is converted to a motor voltage and a displacement of the motor voltage is amplified to generate a source potential at the second field effect transistor (T22), and wherein the current limiting circuit (7) limits the motor current (ID) by switching the semiconductor-switching element (T1) between the ON/OFF operation and the continuous ON operation when the current detection circuit (2) detects that the source potential at a moment is greater than a mean value of the source potential over a long period by another predetermined value. - View Dependent Claims (26, 27)
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Specification