MOTOR DRIVE DEVICE

• US 20090039812A1
• Filed: 11/27/2007
• Published: 02/12/2009
• Est. Priority Date: 11/29/2006
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Imasen Denki Seisakusho, NHK Spring Company Limited
• Original Assignee: Kabushiki Kaisha Imasen Denki Seisakusho, NHK Spring Company Limited
• Inventors: Nakamura, Takeshi, Ueki, Hiroyuki, Sasaki, Akira, Sone, Toshiaki, Sakoguchi, Akira
• Granted Patent: US 7,898,195 B2
• Time in Patent Office: Days
• US Class Current: 318/434
• CPC Class Codes: B60N 2/0244 with logic circuits
• CPC Class Codes: B60N 2/2213 Gear wheel driven mechanism B60N2/2231, B60N2/225 take precedence
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage

Abstract

The present invention presents a motor drive device capable of detecting jamming accurately without falsely detecting jamming when a movable part contacts with other members. Jamming by a backrest is detected by judging whether the value of a period of one pulse P1 and a period of the next pulse P2 (P2/P1) integrated for 150 times (integrated value: 150) exceeds a specified threshold (160) or not. Accordingly, if the backrest rubs against a backrest of an adjacent seat, and the motor speed suddenly drops for a short period, such “warp” is not falsely detected as jamming, and only actual jamming can be detected securely.

Claims

1. A motor drive device comprising a motor for driving a movable part, a motor control device for controlling normal rotation stop or reverse rotation of the motor, and a rotation detector for detecting rotation of the motor and outputting a pulse corresponding to the motor speed,

wherein the motor control device detects jamming by the movable part by judging whether an integral value of change amounts of a pulse period from the rotation detector exceeds a specified threshold or not, and stops or inverts the motor.

2. The motor drive device according to claim 1, wherein the integration of change amounts of the pulse period by the motor control device is executed by:

integrating the ratio of an arbitrary first number of pulse periods, and the same number of pulse periods as the arbitrary first number outputted from the rotation detector after the arbitrary first number of pulses, for an arbitrary second number of times.

3. The motor drive device according to claim 2, wherein the arbitrary first number is one.

4. The motor drive device according to claim 1, wherein the movable part is a backrest of a vehicle seat disposed so as to contact with other members.