Vehicle speed detecting device

• US 4,876,527 A
• Filed: 09/29/1988
• Issued: 10/24/1989
• Est. Priority Date: 09/29/1987
• Status: Expired due to Fees

• Current Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Original Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Inventors: Oka, Hiroki, Nagura, Nobuyoshi
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/250,899
• Time in Patent Office: 390 Days
• Field of Search: 340/52 R, 340/53, 340/669-672, 340/441, 180/170, 180/171, 180/197, 180/282, 303/91, 303/92, 303/94, 303/102, 303/95, 364/426, 364/565, 364/426.01, 364/426.02, 364/426.04, 324/500, 324/160, 324/161, 324/163, 361/236-239, 361/240, 361/242, 235/95 R, 235/95 A
• US Class Current: 340/441
• CPC Class Codes: B60Q 1/54 for indicating speed outside of the vehicle

Abstract

A vehicle speed detecting device utilizes two vehicle speed pulse generators, a vehicle speed memory device, pulse counters, abnormality detectors, pulse signal transfer devices and an alarm device which are all integrated into the electronic control circuit of a micro-processor through two sets of signal processing devices. The detecting device not only indicates the speed of the vehicle but also detects abnormalities in either of the vehicle speed pulse generators and provides an appropriate alarm.

Claims

1. A vehicle speed detecting device comprising first and second vehicle speed pulse generators, each of which provides electrical pulses proportionate to the vehicle speed, vehicle speed calculation means for calculating the vehicle speed based on said electrical pulses, means for memorizing the vehicle speed, means for counting the pulses generated by said vehicle speed pulse generators, abnormality detecting means for producing an abnormal operation signal when the count value of one of said vehicle speed pulse generators is lower than a predetermined value when the vehicle speed calculated by the vehicle speed calculation means is greater than the predetermined vehicle speed, means for transferring the electrical pulses for the calculation of the vehicle speed from one pulse generator to the other pulse generator and means for initiating an alarm in response to the abnormality signal.

2. A method for detecting the abnormality of one of a pair of vehicle speed pulse generators comprising counting electrical pulses generated by first and second vehicle speed pulse generators, generating a first abnormality signal when the count value of the first vehicle speed pulse generator is lower than a specified value and generating a second abnormality signal when the count value of the second vehicle pulse generator is lower than a specific value, transferring the electrical pulses to be calculated by the vehicle speed calculating means in response to the first abnormality signal from the electrical pulses generated from the first vehicle speed pulse generator to the electrical pulses of the second vehicle speed pulse generator;

transferring the electrical pulses to be calculated by the vehicle speed calculating means in response to the second abnormality signal, from electrical pulses generated from the second vehicle speed pulse generator to electrical pulses of the first vehicle speed pulse generator; and

initiating an alarm in response to the said abnormality signals.