Anti-lock brake system and sensor unit for the same

• US 20060170281A1
• Filed: 06/16/2004
• Published: 08/03/2006
• Est. Priority Date: 06/17/2003
• Status: Active Grant

• Current Assignee: Yokohama Rubber Company Limited
• Original Assignee: Yokohama Rubber Company Limited
• Inventors: Hatano, Yasuo, Hattori, Yutaka
• Granted Patent: US 7,481,501 B2
• Time in Patent Office: Days
• US Class Current: 303/20
• CPC Class Codes: B60T 2240/04 Tire deformation
• CPC Class Codes: B60T 8/1725 Using tyre sensors, e.g. Sidewall Torsion sensors [SWT] for tyre pressure and temperature detection B60C23/00
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass
• CPC Class Codes: G01P 3/481 of pulse signals

Abstract

An anti-lock brake system and a sensor unit for the system, where acceleration occurring in a wheel is easily detected with high accuracy to perform braking control of a motor vehicle. Sensor units (100) having acceleration sensors that detect acceleration occurring, with the rotation of tires (300), in X, Y, and Z directions including the tire rotating direction are provided on rotating bodies of rotation mechanism portions including each tire (300). The sensor units (100) transmit digital values of the detected result as digital information by an electromagnetic wave. The digital information is received by a monitor device (200) provided on each tire house, and an acceleration value obtained by calculation is outputted to a brake control unit (600). The brake control unit (600) estimates a strain amount of each tire (300) based on the obtained acceleration value and previously memorized strain characteristic information, controls a pressure regulating valve (630) based on the estimated tire strain amount and a detected result of a rotating speed of each tire (300), and drives a brake driving actuator (640).

Claims

1. A vehicle anti-lock brake system constituted so as to drive a brake driving actuator in accordance with the detection result of a vehicle brake operating state and generate a target braking force, comprising:

a sensor unit set to a rotating mechanism portion including a body of rotation for fixing a wheel set to the vehicle body side and rotating the wheel and the wheel to detect first acceleration generated in the direction orthogonal to a rotating shaft in accordance with rotation and second acceleration generated in the rotating direction, convert the detection results into digital values, and transmit the digital information including the digital values;

a monitor system for receiving the digital information transmitted from the sensor unit and obtaining detection results of the first acceleration and second acceleration; and

driving means for driving the brake driving actuator in accordance with detection results of the first acceleration and second acceleration obtained by the monitor system.

2. The anti-lock brake system according to claim 1, characterized in that

the sensor unit has means for detecting third acceleration generated in the rotating-shaft direction, converting the detection result into a digital value, and transmitting the digital information including the digital value of the third acceleration to the monitor system,

the monitor system has means for obtaining the detection result of the third acceleration, and

the driving means has means for driving the brake driving actuator in accordance with detection results of the first acceleration, second acceleration, and third acceleration.

3. The anti-lock brake system according to claim 1, characterized in that

the sensor unit has means for detecting a change of the second acceleration, means for detecting the rotating speed per unit time in accordance with the change of the second acceleration, and means for converting the detected rotating speed into a digital value and transmitting digital information including the digital value of the rotating speed to the monitor system,

the monitor system has means for receiving the digital value of the rotating speed from the sensor unit, and

the driving means has means for driving the brake driving actuator in accordance with detection results of the first acceleration, second acceleration, and third acceleration and the detection result of the rotating speed.

4. The anti-lock brake system according to claim 1, characterized in that

the sensor unit is set to the body of rotation.

5. The anti-lock brake system according to claim 1, characterized in that

the sensor unit has means for receiving electromagnetic waves of first frequency, means for converting the energy of the electromagnetic waves of the received first frequency into driving electric energy, and means to be operated by the electric energy to transmit the digital information by using electromagnetic waves of second frequency, and

the monitor system has means for radiating electromagnetic waves of the first frequency, means for receiving electromagnetic waves of the second frequency;

and means for extracting the digital information from the received electromagnetic waves of the second frequency.

6. The anti-lock brake system according to claim 5, characterized in that

the first frequency is equal to the second frequency.

7. The anti-lock brake system according to claim 1, characterized in that

the sensor unit has storing means in which identification information specific to its own is stored and means for transmitting the digital information including the identification information, and

the monitor system has means for identifying the rotating mechanism portion in accordance with the identification information.

8. The anti-lock brake system according to claim 1, characterized in that

the sensor unit has a semiconductor acceleration sensor having a silicon-piezo-type diaphragm for detecting accelerations orthogonal to each other.

9. The anti-lock brake system according to claim 1, characterized in that

a rotating speed detecting mechanism set to the rotating mechanism portion to detect first rotating speed per unit time of the wheel and transmit the detection result to the monitor system,

the sensor unit has means for detecting a change of the second acceleration, means for detecting second rotating speed per unit time in accordance with the change of the second acceleration, and means for converting the detected second rotating speed into a digital value and transmitting the digital information including the digital value of the second rotating speed to the monitor system, and

the monitor system has means for receiving the detection result of the first rotating speed from the rotating speed detecting mechanism, means for receiving the detection result of the second rotating speed from the sensor unit, and determining means for determining whether the first rotating speed is equal to the second rotating speed.

10. The anti-lock brake system according to claim 9, characterized in that

the rotating speed detecting mechanism is set to the body of rotation and has a disk whose periphery has a plurality of concave and convex portions and means for generating a magnetic field and detecting a voltage according to a change of the magnetic field.

11. The anti-lock brake system according to claim 9, characterized in that

the rotating speed detecting mechanism has means for converting the detection result of the first rotating speed into a digital signal,

the monitor system has converting means for converting the digital value of the second rotating speed into digital signal, and

the determining means has means for determining whether the first rotating speed is equal to the second rotating speed in accordance with the digital signal of the first rotating speed and the digital signal of the second rotating speed.

12. The anti-lock brake system according to claim 11, characterized in that

the converting means has means for multiplying the digital value of the second rotating speed by a predetermined value and converting the multiplication value into a digital signal having a period of the reciprocal of the multiplication value.

13. The anti-lock brake system according to claim 11, characterized in that

the determining means has means for determining that the first rotating speed is equal to the second rotating speed when the oscillation of the digital signal of the second rotating speed is generated for every predetermined multiples of the period of the digital signal of the first rotating speed.

14. The anti-lock brake system according to claim 1, characterized in that

a rotating speed detecting mechanism is used which is set to the rotating mechanism portion to detect first running speed according to the rotation of the wheel and transmit the detection result to the monitor system,

the sensor unit has means for detecting a change of the first acceleration, means for detecting second running speed per unit time in accordance with the change of the first acceleration, and means for converting the detected second running speed into a digital value and transmitting the digital information including the digital value of the second running speed to the monitor system, and

the monitor system has means for receiving the detection result of the first running speed from the rotating speed detecting mechanism, means for receiving the detection result of the second running speed from the sensor unit, and determining means for determining whether the first running speed is equal to the second running speed.

15. The anti-lock brake system according to claim 14, characterized in that

the rotating speed detecting mechanism set to the body of rotation and has a disk whose periphery has a plurality of concave and convex portions at equal intervals and means for generating a magnetic field and detecting a voltage according to a change of the magnetic field.

16. The anti-lock brake system according to claim 14, characterized in that

the rotating speed detecting mechanism has means for converting the detection result of the first running speed into a digital signal,

the monitor system has converting means for converting the digital value of the second running speed into a digital signal, and

the determining means has means for determining whether the first running speed is equal to the second running speed in accordance with the digital signal of the first running speed and the digital signal of the second running speed.

17. The anti-lock brake system according to claim 16, characterized in that

the converting means has means for multiplying the digital value of the second running speed by a predetermined value and converting the multiplication value into a digital signal having the period of the reciprocal of the multiplication value.

18. The anti-lock brake system according to claim 16, characterized in that

the determining means has means for determining that the first rotating speed is equal to the second rotating speed when oscillations of the digital signal of the second rotating speed are generated for every predetermined multiples of the period of the digital signal of the first rotating speed.

19. A sensor unit set to a rotating mechanism portion including a body of rotation for fixing a wheel set to the vehicle body side to rotate the wheel and the wheel to detect the acceleration generated in accordance with rotation, comprising:

means for detecting first acceleration generated in the direction orthogonal to a rotating shaft in accordance with rotation and second acceleration generated in a rotating direction and means for converting the detection result of the first acceleration and the detection result of the second acceleration into digital values, and means for transmitting the digital information including the digital value.

20. The sensor unit according to claim 19, characterized by comprising:

means for detecting third acceleration generated in the rotating-axis direction, means for converting the detection result of the third acceleration into a digital value, and means for transmitting the digital information including the digital value of the third acceleration.

21. The sensor unit according to claim 19, characterized by comprising:

means for detecting a change of the second acceleration, means for detecting the rotating speed per unit time in accordance with the change of the second acceleration, and means for converting the detected rotating speed into a digital value, and means for transmitting the digital information including the digital value of the rotating speed.

22. The sensor unit according to claim 19, characterized by comprising:

means for receiving a first frequency, means for converting the energy of the electromagnetic waves of the received first frequency into driving electric energy and means to be operated by the electric energy to transmit the digital information by using electromagnetic waves of a second frequency.

23. The sensor unit according to claim 22, characterized in that

the first frequency is equal to the second frequency.

24. The sensor unit according to claim 19, characterized by comprising:

storing means in which identification information specific to its own is stored and means for transmitting the digital information including the identification.

25. The sensor unit according to claim 19, characterized by comprising a semiconductor acceleration sensor which has a silicon piezo-type diaphragm for detecting accelerations in directions orthogonal to each other.