Rotation detecting device and anti-skid braking system using the same

• US 20030234578A1
• Filed: 03/07/2003
• Published: 12/25/2003
• Est. Priority Date: 03/08/2002
• Status: Active Grant

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Iwamoto, Kenichi, Takahashi, Toru, Okada, Koichi, Ohba, Hiroaki
• Granted Patent: US 7,341,321 B2
• Time in Patent Office: Days
• US Class Current: 303/168
• CPC Class Codes: B60T 8/171 Detecting parameters used in the regulation; Measuring values used in the regulation
• CPC Class Codes: B60T 8/329 Systems characterised by their speed sensor arrangements
• CPC Class Codes: F16C 19/186 with three raceways provided integrally on parts other than race rings, e.g. third generation hubs
• CPC Class Codes: F16C 2326/02 Wheel hubs or castors
• CPC Class Codes: F16C 33/7886 mounted outside the gap between the inner and outer races, e.g. sealing rings mounted to an end face or outer surface of a race
• CPC Class Codes: F16C 41/004 Electro-dynamic machines, e.g. motors, generators, actuators
• CPC Class Codes: F16C 41/007 Encoders, e.g. parts with a plurality of alternating magnetic poles
• CPC Class Codes: F16C 41/008 Identification means, e.g. markings, RFID-tags; Data transfer means
• CPC Class Codes: G01P 3/443 mounted in bearings bearings F16C

Abstract

To provide a rotation detecting device compact in structure and operable on its own electric power generating function and capable of detecting the number of revolution of a vehicle wheel even at an extremely low speed rotation of the vehicle wheel, and also an anti-skid braking system utilizing such rotation detecting device, the rotation detecting device includes an electric power generator 4, at least one magnetic sensor 23 and an electric power supply circuit 24. The electric power generator 4 in turn includes a stator 17 and a rotor 18 in the form of a multi-pole magnet having a plurality of opposite magnetic poles alternating in a direction circumferentially of the rotor 18. The magnetic sensor 23 is mounted on either the stator 17 or a support member 1 for supporting the stator 17 and is operable to detect the magnetic poles on the rotor 18. The electric power supply circuit 24 is a circuit in which the electric power generated by the electric power generator 4 is utilized as an electric power source of the magnetic sensor 23. The stator 17 is has a wireless transmitting device 5A mounted thereon for transmitting a detection signal from the magnetic sensor 23. Even this wireless transmitting device 5A utilizes the electric power generated by the electric power generator 4 as an electric power source therefor.

Claims

1. A rotation detecting device which comprises:

an electric power generator including a stator and a rotor, said rotor having a plurality of opposite magnetic poles alternating in a direction circumferentially of the rotor;

at least a first magnetic sensor mounted on either the stator or a support member for supporting the stator and operable to detect the alternating magnetic poles in the rotor; and

an electric power supply circuit for utilizing an electric power generated by the electric power generator as an electric power source for the at least first magnetic sensor.

2. The rotation detecting device as claimed in claim 1, further comprising a second magnetic sensor and wherein the first and second magnetic sensors are disposed so as to align with respective positions displaced 90°

in phase of the cycle of alternating repetition of the opposite magnetic poles in the rotor.

3. The rotation detecting device as claimed in claim 1, wherein the stator includes a ring member made of a magnetic material and a coil accommodated in the ring member, said ring member having two sets of a plurality of claws provided at a portion of the ring member that confronts the rotor, the claws of the two sets extending in respective directions opposite to each other so as to interleaved relative to each other while alternating one after another in a direction circumferentially of the ring member, the neighboring claws being spaced in the circumferential direction with a gap defined therebetween.

4. The rotation detecting device as claimed in claim 3, wherein the ring member has a sensor window defined in a portion the circumference of the ring member for accommodating the first magnetic sensor, said sensor window being defined by depleting some of the claws in the ring member.

5. The rotation detecting device as claimed in claim 1, further comprising a transmitting device for wireless transmitting a sensor output signal from the magnetic sensor and wherein the electric power supply circuit utilizes the electric power generated by the electric power generator also as an electric power source for the transmitting device.

6. The rotation detecting device as claimed in claim 1, wherein the electric power supply circuit includes an electric component part selected from the group consisting of an electric double layer capacitor, a secondary cell and a primary cell.

7. The rotation detecting device as claimed in claim 1, wherein a wireless switching device selectively switches on or off a supply of an electric power from the electric power supply circuit, said wireless switching device including a tuning circuit for detecting a radio wave of a particular frequency and a semiconductor switching element interposed in the electric power supply circuit and capable of being selectively turned on or off in response to a detection signal of the radio wave detected by the tuning circuit, said wireless switching device in its entirety being powered by an electric power of the detection signal of the radio wave detected by the tuning circuit.

8. A bearing assembly equipped with a rotation detecting device, said bearing assembly comprising:

a non-rotatable member, a rotatable member and a plurality of rolling elements interposed between the non-rotatable member and the rotatable member to permit the latter to rotate relative to the former; and

a rotation detecting device of a structure as defined in claim 1, wherein the stator is mounted fixedly on the non-rotatable member and the rotor is mounted on the rotatable member for rotation together therewith.

9. A wheel support bearing assembly for rotatably supporting a wheel relative to a vehicle body structure, said wheel support bearing assembly comprising:

an outer member having a plurality of outer raceways defined in an inner periphery thereof;

an inner member having a corresponding number of inner raceways defined in an outer periphery thereof in alignment with the outer raceways;

a plurality of rolling elements interposed between the outer and inner members and rollingly accommodated in part within one of the outer raceways and in part within a mating one of the inner raceways to permit one of the outer and inner members to rotate relative to the other of the outer and inner members; and

a rotation detecting device of a structure as defined in claims 1, wherein the stator is mounted fixedly on one of the outer and inner members and the rotor is mounted on the other of the outer and inner members.

10. An anti-skid braking system for controlling a braking force to be applied to a wheel brake in dependence on a detection signal detected as indicative of the number of revolution of a wheel, said anti-skid braking system comprising:

a rotation detecting device being of a structure as defined in claim 1, said rotation detecting device being operable to output the detection signal and including a rotor fixedly mounted on a rotatable member rotatable together with the wheel, and a stator mounted fixedly on a wheel support member for supporting the rotatable member; and

a control circuit mounted on the vehicle body structure for controlling the braking force; and

a communicating unit for wireless transmitting the detection signal outputted from the rotation detecting device, said unit including a transmitting device and a receiving device, which are mounted on the wheel support member and a vehicle body structure, respectively.

11. The anti-skid braking system as claimed in claim 10, wherein the electric power supply circuit utilizes the electric power generated by the electric power generator, as an electric power source for the transmitting device.

12. A rotation detecting device which comprises:

a rotation detector having a capability of detecting the rotational speed and including an electric power generator having a rotor and a stator;

a transmitting device for wireless transmitting a rotation signal indicative of the rotational speed detected by the rotation detector;

an electric power supply circuit for utilizing an electric power generated by the electric power generator for electrically powering the transmitting device;

a wireless switching device for selectively switching on or off supply of an electric power from the electric power supply circuit, said wireless switching device including a tuning circuit for detecting a radio wave of a particular frequency and a semiconductor switching element interposed in the electric power supply circuit and capable of being selectively turned on or off in response to a detection signal of the radio wave detected by the tuning circuit, said wireless switching device in its entirety being electrically powered by an electric power of the detection signal of the radio wave detected by the tuning circuit.

13. The rotation detecting device as claimed in claim 12, further comprising a rectifier circuit for rectifying an output from the tuning circuit and a surface acoustic wave filter interposed between the tuning circuit and the rectifier circuit.

14. The rotation detecting device as claimed in claim 12, wherein the electric power supply circuit includes an electric component part selected from the group consisting an electric double layer capacitor, a secondary cell and a primary cell for compensating a reduction of the electric power generated by the electric power generator at a low speed rotation of the rotor.

15. The rotation detecting device as claimed in claim 12, wherein the rotation detector includes a sensor utilizing the electric power generator as an electric power source therefor, the rotational speed being detected by the sensor.

16. The rotation detecting device as claimed in claim 12, wherein the rotor and the stator of the electric power generator are mounted on a rotatable member and a non-rotatable member of a wheel support bearing assembly and wherein the signal transmitted by the wireless transmitting device and indicative of the rotational speed is used for controlling an automobile anti-skid braking system.

18. A wheel support bearing assembly for rotatably supporting a wheel relative to a vehicle body structure, said wheel support bearing assembly comprising:

an outer member having a plurality of outer raceways defined in an inner periphery thereof;

an inner member having a corresponding number of inner raceways defined in an outer periphery thereof in alignment with the outer raceways;

a plurality of rolling elements interposed between the outer and inner members and rollingly accommodated in part within one of the outer raceways and in part within a mating one of the inner raceways to permit one of the outer and inner members to rotate relative to the other of the outer and inner members; and

a rotation detecting device of a structure as defined in claims 12, wherein the stator is mounted fixedly on one of the outer and inner members and the rotor is mounted on the other of the outer and inner members.

19. An anti-skid braking system for controlling a braking force to be applied to a wheel brake in dependence on a detection signal detected as indicative of the number of revolution of a wheel, said anti-skid braking system comprising:

a rotation detecting device including a rotor fixedly mounted on a rotatable member rotatable together with the wheel, and a stator mounted fixedly on a wheel support member for supporting the rotatable member; and

a control circuit mounted on the vehicle body structure for controlling the braking force;

said rotation detecting device being of a structure as defined in claim 12 and including the transmitting device and a receiving device to receive the rotation signal from the transmitting device, which are mounted on the wheel support member and a vehicle body structure, respectively.

20. The anti-skid braking system as claimed in claim 19, further comprising a continuously halted status detector mounted on a mechanism that differs depending on whether an automobile is in a continuously halted status or in a running status, and a switch-off signal transmitting device operable in response to a detection output signal from the continuously halted status detector for transmitting a wireless signal capable of being detected by the tuning circuit of the wireless switching device.

21. The anti-skid braking system as claimed in claim 20, wherein the continuously halted status detector is capable of detecting at least one of continuously halted statuses of the automobile including a condition in which a parking brake is held in a locked position, a condition in which an engine is inactivated, a condition in which an ignition key is removed from an ignition switch, a condition in which a transmission is set to a parking position.

17. A wireless switching device which comprises:

a tuning circuit for detecting a radio wave of a particular frequency; and

a semiconductor switching element interposed in the electric power supply circuit and capable of being selectively turned on or off in response to a detection signal of the radio wave detected by the tuning circuit;

said wireless switching device in its entirety being electrically powered by an electric power of the detection signal of the radio wave detected by the tuning circuit.