JP4840153B2 - Rolling bearing device with sensor - Google Patents

Description

  The present invention relates to a rolling bearing device with a sensor. More specifically, the present invention relates to a sensor-equipped rolling bearing device that detects a load acting on a wheel by a sensor disposed on a fixed race (outer ring) constituting the bearing device.

  2. Description of the Related Art In recent years, various information such as a load acting on a wheel and a rotation speed of a wheel is required in an automobile in order to perform operation control during traveling. In order to obtain such information, it has been proposed to attach a sensor device to a wheel rolling bearing device to which a vehicle wheel is attached.

  As such a sensor device, for example, a magnetic impedance sensor provided in a fixed raceway and a magnetized portion provided in a rotating raceway so as to face the magnetic impedance sensor have been proposed (for example, In this sensor device, the detection by the magnetic impedance sensor is affected by the material, shape, etc. of the detected part, so there are restrictions on the selection of the material of the rolling bearing, the machining of the magnetized part, There is a problem that the addition of another member is required for the detected part.

Therefore, as there are few restrictions on material selection and no additional processing is required, an ultrasonic sensor is installed on the fixed raceway to echo the force acting between the rolling elements and the fixed raceway. Detection as a ratio has been proposed (for example, Patent Document 2).
The rolling bearing device with sensor described in Patent Document 2 is provided with ultrasonic sensors that are provided at at least two locations spaced apart in the circumferential direction of the fixed-side raceway member and detect the rolling element load as an echo ratio, and each ultrasonic wave A sensor device is provided that includes processing means for obtaining at least a vertical component and a horizontal component among the three components of the load acting on the rolling bearing from the output of the sensor. In addition to the three-direction component, it is also possible to obtain moments about the X axis, the Y axis, and the Z axis.

JP 2004-45370 A JP 2006-177932 A

  However, in the detection method of the rolling element load by the ultrasonic echo, that is, the tire ground contact load, since the rolling element passes through the ultrasonic sensor installation location, the echo ratio can be detected. Is dependent on the outer ring passing frequency of the rolling element due to the rotation of the inner ring of the bearing device. In other words, since the load calculation response depends on the speed of the vehicle on which the bearing device is mounted, the response may decrease at low speeds.

  On the other hand, the response of tire ground contact load detection for vehicle motion control requires at least 100 Hz since the natural frequency of a typical radial tire is 90 to 110 Hz, and a method using a conventional ultrasonic sensor However, the problem remains in the load detection response at low speed.

  This invention is made | formed in view of such a situation, and it aims at providing the rolling bearing apparatus with a sensor which can improve the responsiveness of the load detection at the time of low speed.

The rolling bearing device with a sensor according to the present invention includes an outer ring fixed to the vehicle body side, an inner ring fixed concentrically with the outer ring and fixed to the tire side, and a rolling roller disposed between these inner and outer rings. A rolling bearing device with a sensor having a moving body and a sensor device that detects a load that is disposed on the outer ring side and that acts on the rolling body,
The number of rolling elements is an odd number,
The sensor device includes at least a pair of ultrasonic sensors disposed at positions facing each other with respect to the axis of the bearing device,
When A is a constant, n is the number of rolling elements, V is a vehicle speed, r is a tire radius, Da is a rolling element diameter, θ is a contact angle, and dm is a pitch circle diameter, fo = A · n · V / r ( The rolling element outer ring passing frequency fo represented by 1-Da · cos θ / dm) is 50 Hz or more at V ≦ 40 (km / h), and
The sensor device is configured to perform a load calculation using the output of the ultrasonic sensor on the load increase side and the output of the ultrasonic sensor on the load decrease side in a staggered manner among the pair of ultrasonic sensors. It is characterized by.

  In the rolling bearing device with a sensor of the present invention, the rolling element outer ring passing frequency fo, that is, the frequency fo at which the rolling element passes the outer ring portion where the ultrasonic sensor is disposed is 50 Hz or more at V ≦ 40 (km / h). It is supposed to be. The output of the ultrasonic sensor on the load increasing side and the load decreasing side of the pair of ultrasonic sensors arranged at positions opposite to each other with respect to the shaft center of the bearing device having an odd number of rolling elements The outputs of the ultrasonic sensors are used in a staggered manner to calculate the load. When the number of rolling elements is an odd number, the outputs of the pair of ultrasonic sensors can appear alternately, and when these outputs are used in a staggered manner as will be described later, the opportunity of load calculation is given to each ultrasonic wave. The output number of the sensor (the rolling element outer ring passing frequency fo) can be doubled. Therefore, even when V ≦ 40 (km / h), the calculation response can be 50 Hz × 2 = 100 Hz or more, and the response at low speed can be improved.

The number n of rolling elements and the diameter Da (mm) of rolling elements are
Da = 5.6,
Da = an + b, and Da = cn ² + dn + e
Is preferably selected within a range surrounded by a straight line or a curve represented by Within this range, by selecting the number of rolling elements n and the rolling element diameter Da, the rolling element outer ring passing frequency fo is set to V ≦ V while keeping the bearing size within a predetermined range and ensuring the specified life of the bearing. It can be set to 50 Hz or more at 40 (km / h).

  According to the rolling bearing device with a sensor of the present invention, it is possible to improve the load detection response at low speed.

Embodiments of a rolling bearing device with a sensor according to the present invention (hereinafter also simply referred to as “bearing device”) will be described in detail below with reference to the accompanying drawings.
FIG. 1 is an axial cross-sectional explanatory view of a bearing device H according to an embodiment of the present invention. In FIG. 1, the right side is the vehicle outer side (the outside of the vehicle), and the left side is the vehicle inner side (the inside of the vehicle).

  As shown in FIG. 1, the bearing device H of the present embodiment includes a cylindrical outer ring 1, an inner shaft 2 that is rotatably inserted into the outer ring 1, and a vehicle inner of the inner shaft 2. An inner ring member 3 fitted on the side end portion, a sensor device 4 provided on the outer ring 1, and a double row rolling elements 5, 5 composed of a plurality of balls arranged in the circumferential direction. These constitute a double-row angular contact ball bearing portion. The balls in each row as the rolling elements 5 and 5 are held by the holder 6 at a predetermined interval in the circumferential direction.

  In the present specification, the direction along the center line C of the bearing device H is defined as the Y-axis direction, the horizontal direction perpendicular to the paper surface is defined as the X-axis direction, and is orthogonal to the Y-axis direction and the X-axis direction. The vertical direction is defined as the Z-axis direction. Accordingly, the X-axis direction is the front-rear horizontal direction of the wheel, the Y-axis direction is the left-right horizontal direction (axial direction) of the wheel, and the Z-axis direction is the vertical direction.

  In the bearing device H of the present embodiment, the outer ring 1 is a fixed race that is fixed to the vehicle body side. On the other hand, the inner shaft 2 and the inner ring member 3 are wheel-side rotating race rings (inner rings), and the double row rolling elements between the fixed race rings (outer rings) and the rotating race rings (inner rings). 5 and 5 are movably interposed. Thereby, the fixed raceway and the rotary raceway are arranged coaxially with each other, and the rotary raceway is rotatable with the wheel (not shown) with respect to the fixed raceway.

  The inner shaft 2 constituting the rotating raceway has a flange portion 7 extending radially outward on the vehicle outer side, and this flange portion 7 serves as a mounting portion of a wheel tire wheel or a brake disk. The tire wheel and the like are attached to the flange portion 7 by means of attachment bolts 14. The inner ring member 3 is externally fitted to a step portion formed on the vehicle inner side of the inner shaft 2, and is fixed to the inner shaft 2 by a nut 8 that is screwed to an end portion of the inner shaft 2 on the vehicle inner side. The inner raceway surfaces 9 and 9 of the rolling elements 5 and 5 are formed on the outer peripheral surface of the inner shaft 2 and the outer peripheral surface of the inner ring member 3, respectively.

The outer ring 1 constituting the fixed raceway includes a cylindrical main body cylinder portion 11 in which the outer raceway surfaces 10 and 10 of the rolling elements 5 and 5 are formed on the inner peripheral surface, and a radial direction from the outer peripheral surface of the main body cylinder portion 11. And a flange portion 12 extending outward. The flange portion 12 is fixed to a knuckle (not shown) of a suspension device that is a vehicle body side member, whereby the bearing device H is fixed to the vehicle body side.
A seal device 20 is provided between the inner peripheral surface of the outer side of the outer ring 1 and the outer peripheral surface of the inner shaft 2 facing this, and the inner peripheral surface of the end of the outer ring 1 on the inner side of the vehicle. A cover 21 is press-fitted in.

The sensor device 4 is connected to an ultrasonic sensor 41 that detects a force acting between the outer ring 1 and the rolling element 5, and the ultrasonic sensor 41 through a lead wire (not shown). And processing means (not shown).
In addition to the uppermost part (top) and the lowermost part (bottom) of the outer ring 1 shown in FIG. 1, the ultrasonic sensors 41 are also provided on the front side and the rear side of the upper and lower intermediate parts of the outer ring 1, respectively. In other words, two pairs of ultrasonic sensors 41 that are disposed at 90 ° intervals in the circumferential direction of the outer ring 1 and that are disposed at positions facing each other with respect to the axis of the bearing device H are disposed. .

  The ultrasonic sensor 41 has a cylindrical case having an external thread formed on the outer peripheral surface and a vibrator disposed in the case, and is provided on a contact surface between the rolling element 5 and the outer raceway surface 10. It faces from the vertical direction. The outer ring 1 is formed with a bottomed female screw portion so that the screwing amount of the case can be adjusted. Between the front end surface of the case and the bottom surface of the female screw portion, a rubber cushion sheet 42 for protecting the front end surface of the ultrasonic sensor 41 is interposed. Further, a nut 43 for preventing rotation of the case is screwed to a proximal end portion of the male screw portion of the case.

The ultrasonic sensor 41 emits ultrasonic waves from the transmission / reception surface toward the contact portion between the rolling element 5 and the outer raceway surface 10 and receives the reflected wave reflected by the contact portion at the transmission / reception surface. The force acting on the moving body 5 is detected as an echo ratio shown below.
Echo ratio = 100 × (H0−H1) / H0
H0: Echo intensity when the rolling element 5 is located a half pitch away from the ultrasonic sensor 41 H1: Echo intensity when the rolling element 5 is located directly below the ultrasonic sensor 41 This echo ratio acts on the rolling element 5 The force acting on the rolling element 5 can be obtained from the echo ratio using this relationship. When the force acting on the rolling element 5 increases, the contact area between the rolling element 5 and the outer raceway surface 10 increases and the echo intensity decreases. Accordingly, when the force acting on the rolling element 5 is large, a large echo ratio is output.

  When the load acting on the tire fluctuates in accordance with the speed change or posture change of the traveling vehicle, the external force applied to the inner shaft 2 changes according to the change in the load, and the magnitude of the force acting on the rolling element 5 changes. In addition, the manner in which the force is applied to the inner shaft 2 is different for each component in the front-rear direction, the left-right direction, and the vertical direction of the load acting on the tire. Therefore, the influence degree to the force which acts on the rolling element 5 which each ultrasonic sensor 41 detects for every component of each direction differs.

  Therefore, the force acting on the rolling element 5 when a load in the front-rear direction is applied to the tire, the echo ratio output from each ultrasonic sensor 41 corresponding thereto, and the rolling element 5 when a load in the left-right direction is applied. The acting force and the echo ratio output from each ultrasonic sensor 41 corresponding thereto, the force acting on the rolling element 5 when a vertical load is applied, and the corresponding ultrasonic sensor 41 output By obtaining the echo ratio, the components in three directions of the load acting on the tire can be obtained from the echo ratio obtained by each ultrasonic sensor 41. Note that the processing means of the sensor device 4 acts on the rolling element 5, an equation for obtaining the echo ratio, an equation for obtaining a force acting on the rolling element 5 corresponding to the position of each ultrasonic sensor 41 from the echo ratio, and the rolling element 5. There are provided a storage unit that stores formulas for obtaining front and rear loads, left and right loads, and vertical loads that act on the tire from force, a calculation unit that calculates these formulas, and the like.

The feature of the present invention is expressed by fo = A · n · V / r (1−Da · cos θ / dm) in order to improve the load detection, particularly when the vehicle is traveling at a low speed. The rolling element outer ring passing frequency fo is 50 Hz or more when V ≦ 40 (km / h). In the above formula, A is a constant, n is the number of rolling elements, V is a vehicle speed, r is a tire radius, Da is a rolling element diameter, θ is a contact angle, and dm is a pitch circle diameter. The constant A is 10 ⁶ / (120 ² · π).

  In the present invention, the number of rolling elements is an odd number, and the output of the ultrasonic sensor on the load increasing side among the pair of ultrasonic sensors disposed at positions facing each other with respect to the axis of the bearing device H. And the output of the ultrasonic sensor on the load reduction side are used in a staggered manner to calculate the load. The load increasing side is the side where the load is relatively increased, and the load decreasing side is the side where the load is relatively decreasing compared to the load increasing side. For example, when an upward load (Z-axis direction) is applied to the inner shaft 2, the uppermost part (top) of the outer ring 1 is on the load increasing side, and the lowermost part (bottom) is on the load decreasing side. Similarly, when the vehicle is braked during traveling and a vehicle body rearward (X-axis direction) load is applied to the inner shaft 2, the front side of the upper and lower intermediate portions of the outer ring 1 is the load reducing side, and the rear side of the intermediate portion is The load increases.

FIG. 2 shows an example of the time change of the echo ratio detected by the ultrasonic sensor, where (a) shows an even number of rolling elements and (b) shows an odd number of rolling elements. It is. As described above, the load acting on the rolling element can be obtained by using the echo ratio detected for each of the load increasing side and the load decreasing side, according to a formula obtained in advance. Further, when the ultrasonic sensors are arranged above and below the bearing device H, the load component force acting on the bearing device H is calculated using two echo ratios, that is, the echo ratio h1 on the load increase side and the echo ratio h2 on the load decrease side. Among them, the left and right loads and the vertical load can be obtained, and the left and right loads and the vertical load acting on the tire can be obtained from a geometric relationship with the load component acting on the bearing device H. That is, it can be obtained by the left-right load Fy = a (h1 + h2) + b and can be obtained by the vertical load Fz = a′h1 + b′h2 + c ′. Here, a and b are constants determined by bearing specifications, and a ′, b ′ and c ′ are conversion coefficients between the tire contact surface coordinates and the bearing device coordinates.
When two echo ratios are used, only two component forces can be calculated. When the two echo ratios are arranged above and below the bearing device H, the two component forces (left and right loads and vertical loads) are obtained. When arranged before and after, the longitudinal load and the lateral load can be obtained. In other words, four echo ratios are required in order to detect front / rear, left / right, and upper / lower three component forces.
When the number of rolling elements is an even number, as shown in FIG. 2A, the rolling elements simultaneously pass through the ultrasonic sensor on the load increasing side and the ultrasonic sensor on the load decreasing side, and as a result, The peak of the echo ratio is detected. In the figure, the load acting on the tire is calculated using the upper and lower echo ratios. Similarly, the load acting on the tire is sequentially calculated using the upper and lower echo ratios adjacent thereto. However, the load calculation when the number of rolling elements is an even number cannot be performed until the next rolling element passes in the vicinity of the ultrasonic sensor on the load increasing side (load decreasing side), and the movement of the rolling elements becomes slow. When the vehicle runs at a low speed, a decrease in responsiveness becomes a problem.

  On the other hand, when the number of rolling elements is an odd number, as shown in FIG. 2B, the peak of the echo ratio on the load increase side and the peak of the echo ratio on the load decrease side are detected alternately. . Therefore, the load that depends on the tire is calculated using the echo ratio A on the load increase side and the echo ratio a on the load decrease side, and then the echo ratio a on the load decrease side and the echo ratio B on the load increase side The echo ratio on the load increase side and the echo ratio on the load decrease side can be calculated in a “staggered” manner. As a result, the time interval Ib between load calculations can be halved compared to the time interval Ia when the number of rolling elements is an even number. By setting the rolling element outer ring passing frequency fo to 50 Hz or more when V ≦ 40 (km / h) as described above, the calculation response is 50 Hz × 2 = 100 Hz even when V ≦ 40 (km / h). Thus, the response at low speed can be improved.

  In order to increase the outer ring passing frequency fo from the expression fo = A · n · V / r (1−Da · cos θ / dm) representing the outer ring passing frequency fo, for example, the number of rolling elements is increased, The diameter of the rolling element may be reduced, but considering the size and life of the bearing, there are preferable ranges for the number and diameter of the rolling elements. FIG. 3 is a diagram showing an example of a preferable range of the number of rolling elements (balls) and the diameter of the rolling elements. When the number and diameter of the rolling elements are selected within a range surrounded by three straight lines or curves, the size of the bearing is selected. The rolling element outer ring passing frequency fo can be set to 50 Hz or more at V ≦ 40 (km / h) while keeping the bearing within a predetermined range and ensuring the specified life of the bearing. In FIG. 3, when the number of rolling elements is X and the rolling element diameter is Y, the straight line L represents the rolling element diameter (about 5.6 mm) that is equal to or less than the contact surface pressure ensuring the specified life of the bearing. 6 is shown. The straight line M indicates the maximum value (limit value) of the rolling element diameter at which the PCD (pitch circle diameter) is equal to or less than the PCD (maximum of about 70 mm) of the current vehicle bearing device at an arbitrary number of rolling elements. . Further, the curve N indicates the maximum value (limit value) of the rolling element diameter at which the measurement frequency of the tire contact load at a vehicle speed of 40 km / h is 100 Hz or more at an arbitrary number of rolling elements. When the number of rolling elements and the diameter of the rolling elements are selected within the range of the approximate triangle surrounded by the above three straight lines or curves, the contact surface pressure is ensured to ensure the specified life of the bearing, and the PCD is the current vehicle bearing device. PCD (maximum of about 70 mm) or less, and the tire contact load measurement frequency at a vehicle speed of 40 km / h is 100 Hz or more.

  If a diagram as shown in FIG. 3 is prepared in advance, the number and diameter of rolling elements can be easily selected. Note that FIG. 3 is merely an example, and a similar diagram can be appropriately created according to the specifications of the bearing device.

  FIG. 4 is a diagram showing the calculation responsiveness of the example and the comparative example, and the main specifications of the bearing device according to the example and the comparative example are as shown in Table 1.

  As can be seen from FIG. 4, for the same vehicle speed, the example shows a calculation response that is about twice that of the comparative example.

It is an axial section explanatory drawing of one embodiment of a bearing device of the present invention. The example of the time change of the echo ratio detected by an ultrasonic sensor is shown, (a) is a case where the number of rolling elements is an even number, (b) is a case where the number of rolling elements is an odd number. It is a figure which shows the example of the preferable range of the number of rolling elements, and the diameter of a rolling element. It is a figure which shows the calculation responsiveness of an Example and a comparative example.

Explanation of symbols

Reference Signs List 1 outer ring 2 inner shaft 3 inner ring member 4 sensor device 5 rolling element 10 outer raceway surface 41 ultrasonic sensor

Claims (2)

An outer ring fixed to the vehicle body side, an inner ring concentric with the outer ring and fixed to the tire side, a rolling element disposed between these inner and outer rings so as to be freely rotatable, and disposed on the outer ring side A sensor-equipped rolling bearing device having a sensor device that detects a load acting on the rolling element,
The number of rolling elements is an odd number,
The sensor device includes at least a pair of ultrasonic sensors disposed at positions facing each other with respect to the axis of the bearing device,
When A is a constant, n is the number of rolling elements, V is a vehicle speed, r is a tire radius, Da is a rolling element diameter, θ is a contact angle, and dm is a pitch circle diameter, fo = A · n · V / r ( The rolling element outer ring passing frequency fo represented by 1-Da · cos θ / dm) is 50 Hz or more at V ≦ 40 (km / h), and
The sensor device is configured to perform a load calculation using the output of the ultrasonic sensor on the load increase side and the output of the ultrasonic sensor on the load decrease side in a staggered manner among the pair of ultrasonic sensors. A rolling bearing device with a sensor characterized by The number n of rolling elements and the diameter Da (mm) of rolling elements are
Da = 5.6,
Da = an + b, and Da = cn ² + dn + e
The rolling bearing device with a sensor according to claim 1, which is selected within a range surrounded by a straight line or a curved line represented by:

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