Sensor Device and Rolling Bearing with Sensor

• US 20080037920A1
• Filed: 11/24/2005
• Published: 02/14/2008
• Est. Priority Date: 11/24/2004
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: Lou, Liming
• Granted Patent: US 7,854,169 B2
• Time in Patent Office: Days
• US Class Current: 384/448
• 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 19/522 related to load on the bearing, e.g. bearings with load sensors or means to protect the bearing against overload
• CPC Class Codes: F16C 2326/02 Wheel hubs or castors in general B60B
• CPC Class Codes: F16C 33/586 outside the space between the races, e.g. end faces or bore of inner ring
• CPC Class Codes: G01L 5/0004 Force transducers adapted for mounting in a bore of the force receiving structure G01L5/0009 takes precedence
• CPC Class Codes: G01L 5/0009 Force sensors associated with a bearing testing of bearings G01M13/04
• CPC Class Codes: G01L 5/16 for measuring several components of force
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

A sensor device includes: a detected part D having a movable element 5 and a fixed element 3 contacting each other in which a contact area of the both elements changes corresponding to an external load; a contact area detection sensor 2, provided to the fixed element 3, for detecting the contact area of the detected part D; and processing means for calculating the external load from an sensor output by using the correlation between the external load and the contact area.

Claims

1. A sensor device comprising:

a detected part including a movable element and a fixed element contacting each other in which a contact area of both elements changes corresponding to an external load;

a contact area detection sensor, provided to the fixed element, for detecting the contact area of the detected part; and

processing means for calculating the external load from an sensor output by using a correlation between the external load and the contact area.

2. The sensor device as claimed in claim 1, wherein

the movable element is a rolling element of a rolling bearing, and the fixed element is a fixed ring of the rolling bearing.

3. The sensor device as claimed in claim 2, wherein

the processing means comprises:

a theoretical formula storage for storing a theoretical formula showing a relationship between a rolling element load and the contact area;

an empirical formula storage for storing an empirical formula showing a relationship between a sensor output and the contact area;

a contact area calculation unit for calculating the contact area from the sensor output by using the empirical formula; and

a rolling element load calculation unit for calculating the rolling element load from the contact area by using the theoretical formula.

4. The sensor device as claimed in claim 3, wherein

the contact area detection sensor is an ultrasonic sensor which measures a change in the contact area with an echo of an ultrasonic wave.

5. The sensor device as claimed in claim 4, wherein

the ultrasonic sensor has a plurality of vibrators aligned at a prescribed pitch inside thereof.

6. The sensor device as claimed in claim 5, wherein

the plurality of vibrators are arranged at an equal pitch, and the pitch of the vibrator multiplied by a number of vibrators equals one pitch of the rolling element.

7. A rolling bearing device with a sensor comprising:

a rolling bearing;

a contact area detection sensor mounted to the rolling bearing; and

processing means including an empirical formula storage, a theoretical formula storage, a contact area calculation unit, a rolling element load calculation unit, and a three-directional force component calculation unit.

9. A method of calculating three-directional force components in the rolling bearing device with a sensor of claim 7, comprising the steps of:

emitting an ultrasonic wave from the contact area detection sensor to a contact surface of a rolling element and a raceway groove of the rolling bearing;

in the contact area calculation unit, converting an output of an ultrasonic wave from the contact surface of the rolling element and the raceway groove into a contact area by using a relationship between the output and the contact area stored in the empirical formula storage;

in the rolling element load calculation unit, converting the contact area obtained in the contact area calculation unit into a rolling element load by using a relationship between a load and the contact area stored in the theoretical formula storage; and

in the three-directional force component calculation unit, calculating three-directional force components by using the rolling element load obtained in the rolling element load calculation unit.

8. A rolling bearing device with a sensor comprising:

a rolling bearing;

an ultrasonic sensor; and

processing means having an empirical formula storage for storing a relationship previously measured by using the ultrasonic sensor between an echo ratio and a rolling element load, a rolling element load calculation unit for calculating the rolling element load from the echo ratio, and a three-directional force component calculation unit from the rolling element load.

10. A rolling bearing device with a sensor comprising:

a rolling bearing having a fixed side raceway member, a rotational side raceway member, and a rolling element; and

a sensor device, wherein

the sensor device includes;

ultrasonic sensors, provided at least two positions with a prescribed interval in a peripheral direction of the fixed side raceway member, for detecting a rolling element load as an echo ratio; and

processing means for calculating at least an up and down directional component and a left and right directional component among three-directional force components of a load acting on the rolling bearing from outputs of respective ultrasonic sensors.

11. The rolling bearing device with a sensor as claimed in claim 10, wherein

the ultrasonic sensor includes a cylindrical case having an external thread formed on an outer periphery thereof and a vibrator disposed inside the case, and the external thread of the case is screwed into an internal thread with a bottom provided in the fixed side raceway member whereby a prescribed preload is set at a tip of the case.

12. The rolling bearing device with a sensor as claimed in claim 10, wherein

the ultrasonic sensor includes a cylindrical case with a flange part for being mounted to the fixed side raceway member and a vibrator disposed inside the case, and bolts inserted from bolt insertion holes provided in the flange part are screwed into internal threads with bottoms provided in the fixed side raceway member whereby a prescribed preload is set at a tip of the case.

13. The rolling bearing device with a sensor as claimed in claim 10, wherein

the rolling bearing is a hub unit for a motor vehicle, and following equations (1) are provided in the processing means as equations for obtaining a load acting on the hub unit from the roiling element load:

f1=a+bFy+cFz+dMx
f2=a+bFy+cFx+dMz
f3=a+bFy−

cFz−

dMx
f4=a+bFy−

cFx−

dMz
f5=a−

bFy+cFz−

dMx
f6=a−

bFy+cFx−

dMz
f7=a−

bFy−

cFz+dMx
f8=a−

bFy−

cFx+dMz 

 

equations (1)

where a is rolling element load by preload of the hub unit, b, c, d are coefficients not depending on external force, Fx, Fy, Fz are respectively front and back (x axis) directional components left and right (y axis) directional component and up and down (Z axis) directional component of a load, Mx and Mz are moments about x axis and z axis, and f1 to f8 are rolling element loads at respective sensor positions.

14. The rolling bearing device with a sensor as claimed in claim 13, wherein

a number of sensors is two, and the processing means calculates the up and down directional component and the left and right directional component of the load acting on the rolling bearing from appropriate two equations among the equations (1) and a following equation (2):

Mx=r*Fy+e*Fz 

 

equation (2)

where r is wheel rolling radius, and e is difference between acting point of Fz and center of the hub unit in an y axial direction.

15. The rolling bearing device with a sensor as claimed in claim 13, wherein

a number of sensors is four, and the processing means calculates the up and down directional component, the front and back directional component and the left and right directional component of the load acting on the rolling bearing from appropriate four equations among the equations (1), the equation (2) and a following equation (3):

My=r*Fx 

 

equation (3)

where My is moment about y axis.

16. The rolling bearing device with a sensor as claimed in claim 10, wherein the load acting on the rolling bearing is calculated by using the echo ratio measured by the ultrasonic sensor, and following equations (4) to (6) are provided in the processing means as equations therefor:

j1=k+lFy+mFz+NMx
j2=k+lFY+mFx+nMz
j3=k+lFY−

mFz−

nMx
j4=k+lFy−

mFx−

nMz 

 

equations (4,
j5=k−

lFy+mFz−

nMx
j6=k−

lFY+mFX−

nMz
j7=k−

lFy−

mFz+nMx
j8=k−

lFy−

mFx+nMz
Mx=r*Fy+e*Fz 

 

equation (5)
My=r*Fx 

 

equation (6)

where k is echo ratio by preload of the hub unit, l, m, n respectively are coefficients not depending on external force, Fx, Fy, and Fz respectively are front and back (x axis) directional component left and right (y axis) directional component and up and down (z axis) directional component of load, Mx, My, and Mz are moments about x axis, y axis and z axis, j1 to j8;

echo ratios at respective sensor positions, r is wheel rolling radius, e is difference between acting point of Fz and center of the hub unit in an y axial direction.