Arrangement for detecting relative angular movement of a steering wheel

• US 3,980,999 A
• Filed: 08/20/1975
• Issued: 09/14/1976
• Est. Priority Date: 08/26/1974
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Nishioka, Tetsuji, Yanagishima, Takayuki
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US05/666,277
• Time in Patent Office: 391 Days
• Field of Search: 340/52 R, 340/52 D, 340/53, 340/279, 340/271, 180/99
• US Class Current: 340/457
• CPC Class Codes: B60K 28/06 responsive to incapacity of driver
• CPC Class Codes: B60W 2540/18 Steering angle
• CPC Class Codes: G08B 21/02 Alarms for ensuring the safety of persons

Abstract

The steering movement of a motor vehicle is translated into an electrical signal which increases as the steering wheel rotates in one direction and decreases as the steering operation is reversed. This signal is applied to a minimum value detecting and storage circuit and a maximum value detecting and storage circuit, each including a storage capacitor, a switching diode for controlling the charge or discharge of the capacitor, and a bypass switching circuit connected across the diode. The diode of the minimum detector is connected such that it allows the capacitor to be discharged, while the diode of the maximum detector allows the capacitor to be charged. The bypass switching circuit of the minimum detector provides a charging path to the capacitor, while the bypass circuit of the maximum detector provides a discharging path to the capacitor. The voltages developed across the two capacitors are measured and compared with a reference voltage. A reset signal will be produced when the difference voltage exceeds the reference voltage. The reset signal is used to operate the two bypass switching circuits simultaneously to reset either of the stored values depending upon the instantaneous values of the electrical signal.

Claims

1. Arrangement for detecting the relative angular movement of the steering wheel of a motor vehicle, comprising:

a transducer for translating the angular position of said steering wheel into an electrical signal of correspondingly varying voltage;

first means responsive to a decreasing portion of said electrical signal for detecting the minimum voltage of said decreasing portion and storing the electrical signal at the detected minimum voltage;

second means responsive to an increasing portion of said electrical signal for detecting the maximum voltage of said increasing portion and storing the electrical signal at the detected maximum voltage;

means for detecting the difference between the stored signals at the minimum and maximum voltages;

means for comparing said difference with a reference value to provide an output when said difference reaches the reference value; and

means responsive to said output for resetting the voltage of the stored electrical signals to the instantaneous value of said electrical signal at the instant of occurrence of said output.

2. Arrangement according to claim 1, wherein the resetting means increases the voltage of the signal stored in said first means when the same is smaller than said instantaneous value and decreases the voltage of the signal stored in said second means when the same is greater than said instantaneous value.

3. Arrangement for detecting the relative angular movement of the steering wheel of a motor vehicle, comprising:

a transducer for translating the angular position of said steering wheel into an electrical signal of correspondingly varying voltage;

a minimum detector including a first storage capacitor, a first diode connected between the transducer and the first storage capacitor, and a first bypass circuit which, when completed, provides a short circuit across the diode, whereby the first storage capacitor is charged by said electrical signal through said bypass circuit and discharged through said diode;

a maximum detector including a second storage capacitor, a second diode connected between the transducer and the second storage capacitor, and a second bypass circuit which, when completed, provides a short circuit across the second diode, whereby the second storage capacitor is charged by said electrical signal through said second diode and discharged through said second bypass circuit;

means connected to said minimum and maximum detectors for detecting the diffence in voltage between the charges stored in said first and second storage capacitors;

means for comparing said difference with a reference value to provide an output when said difference reaches the reference value; and

means responsive to said output for completing said first and second bypass circuits thereby providing a short circuit across each of the first and second diodes.

4. Arrangement according to claim 3, wherein said minimum detector includes a differential amplifier having a first and a second input terminal and an output terminal, a feedback circuit connected between said output and second terminals, a resistor network connected to a DC voltage source for providing an equal DC potential to said first and second input terminals, said first input terminal being connected to said transducer to receive said electrical signal and said first diode being connected at its anode electrode to the output terminal of said differential amplifier.

5. Arrangement according to claim 3, wherein said maximum detector includes a differential amplifier having a first and a second input terminal and an output terminal, a feedback circuit connected between said output and second terminals, a resistor network connected to a DC voltage source for providing an equal DC potential to said first and second terminals, said first input terminal being connected to said transducer to receive said electrical signal and said second diode being connected at its cathode electrode to the output terminal of said differential amplifier.

6. In a safety apparatus for a motor vehicle including a detector for detecting the movements of the steering wheel of the vehicle and means responsive to the detection of the steering movements for measuring the interval between successive steering movements, and means for alerting the vehicle driver when said interval is in excess of a predetermined interval, said detector comprising:

means for translating the direction of rotation of the steering wheel to provide a corresponding electrical signal which increases when the steering wheel rotates in one direction and decreases when the steering wheel rotates in the opposite direction;

means for storing a minimum value of said electrical signal including a first storage capacitor, a first switching circuit connected between the translating means and the first capacitor which, when operated, provides a path for charging said capacitor with the electrical signal, and a first diode connected between the translating means and said capacitor to discharge the same by an amount proportional to the voltage difference across said diode;

means for storing a maximum value of said electrical signal including a second storage capacitor, a second diode connected between the translating means and the second capacitor to charge the same by an amount proportional to the voltage difference therebetween, and a second switching circuit connected across said second diode which, when operated, discharges said second capacitor by an amount proportional to the voltage developed across the second diode;

means connected to said first and second storage capacitors for detecting the difference between the voltages developed across said capacitors;

means for comparing the voltage difference with a predetermined value to provide an output when said voltage difference reaches the predetermined value and;

means for operating said first and second switching circuits simultaneously in response to said output.