Diagnostic device for electric mechanism drive circuits

• US 6,784,687 B2
• Filed: 06/09/2003
• Issued: 08/31/2004
• Est. Priority Date: 06/10/2002
• Status: Expired due to Fees

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Tamura, Hideki
• Primary Examiner(s): TANG, MINH NHUT
• Application Number:
  US10/457,925
• Publication Number:
  US 20030231029A1
• Time in Patent Office: 449 Days
• Field of Search: 324/510-511, 324/545, 324/158.1, 324/771-772, 318/286, 318/434, 318/490, 318/798-805, 318/811-812, 388/903, 388/907.5
• US Class Current: 324/765.01
• CPC Class Codes: H02H 7/0844 Fail safe control, e.g. by comparing control signal and controlled current, isolating motor on commutation error

Abstract

A diagnostic device for drive circuits has first and second relays each with a movable contact for switching between a normally closed and open contact, a motor are connected to the contacts, first and second resistance voltage dividing circuits connected between the contacts and a reference potential point, a switching circuit connected between two the closed contacts and the reference potential point, and a diagnostic section. The diagnostic section diagnoses a state of supply of drive power to the motor based on voltage-division outputs of the first and second resistance voltage dividing circuits. A bias voltage is supplied to a connection point between the normally closed contacts and the switching circuit. An additional resistance voltage dividing circuit is connected between the connection point and the reference potential pointy. The connection between the motor and a circuit driving the motor based on a voltage-division output of the additional voltage dividing circuit.

Claims

1. A diagnostic device for electric mechanism drive circuits comprising:

an electric mechanism,

a drive circuit, provided with a pair of relays connected to the electric mechanism and a switching circuit connected between normally closed contacts of the pair of relays and a reference potential point, for driving the electric mechanism,

an operation controller for regulating the drive circuit to control operation of the electric mechanism,

voltage dividing circuits connected between the electric mechanism and the drive circuit, and

a diagnostic section for diagnosing a state of supply of drive power to the electric mechanism on the basis of voltage-division outputs of the voltage dividing circuits, wherein

a bias voltage supply circuit is provided to supply a bias voltage between connection points between the normally closed contacts of the pair of relays and the switching circuit,

wherein an additional voltage dividing circuit is connected between the connection points and the reference potential point, and

wherein the diagnostic section diagnoses a connection state of the electric mechanism and the drive circuit, in a state in which the switching circuit is turned off, on the basis of the voltage-division outputs of the additional voltage dividing circuit.

2. The diagnostic device for electric mechanism drive circuits according to claim 1, wherein the additional voltage dividing circuit has a capacitance element constituting an integrating circuit connected between a voltage division point and the reference potential point.

3. The diagnostic device for electric mechanism drive circuits according to claim 1, wherein the additional voltage dividing circuit has a constant voltage setting element connected between a voltage division point and the reference potential point.