JP4872799B2 - State quantity measuring device for rolling bearing units - Google Patents

Description

  The state quantity measuring device for a rolling bearing unit according to the present invention is used to measure the rotational speed of the hub constituting the rolling bearing unit or the state quantity (physical quantity) such as an external force acting between the hub and the outer ring. To do. Further, the obtained state quantity is used for ensuring the running stability of a vehicle such as an automobile.

  For example, automobile wheels are rotatably supported by a suspension device by a double-row angular type rolling bearing unit. In order to ensure the running stability of automobiles, for example, anti-lock braking system (ABS), traction control system (TCS), and electronically controlled vehicle stability control system (ESC) etc. The device is in use. In order to control such various vehicle running stabilization devices, signals representing the rotational speed of the wheels, acceleration in each direction applied to the vehicle body, and the like are required. Of these, the structure for obtaining a signal representing the rotation speed is described in many publications such as Patent Document 1, and various structures have been conventionally implemented and are well known.

  As shown in FIGS. 1A and 1B, the rotational speed detection device basically includes a combination of encoders 1a and 1b and sensors 2a and 2b. Among these, the encoders 1a and 1b are obtained by changing the characteristics (generally magnetic characteristics) of the surface to be detected alternately and at equal intervals in the circumferential direction. Connect and fix concentrically with this hub. The sensors 2a and 2b are supported by an outer ring or the like that is coupled and fixed to the suspension device and does not rotate in a state where the detection unit faces the detection surface of the encoders 1a and 1b. In the case of the structure shown in FIG. 1A among the two types of structures shown in FIG. 1, the detection part of the sensor 2a is opposed to the axial side surface of the annular encoder 1a in the axial direction. In the case of the structure shown in (B), the detection portion of the sensor 2b is opposed to the outer peripheral surface of the cylindrical or annular encoder 1b in the radial direction. In any structure, the output signals of the sensors 2a and 2b change at a frequency proportional to the rotational speed of the wheels as the encoders 1a and 1b rotate in synchronization with the wheels. This rotational speed can be obtained by sending it to the calculator.

  The control of various vehicle running stabilization devices that are currently put into practical use mainly includes signals representing the rotational speed of the wheels required by the above-described structure, and signals from acceleration sensors and yaw rate sensors provided on the vehicle body. Based on. On the other hand, in order to perform a higher degree of control, it is conventional to use a signal indicating the magnitude of a load (for example, one or both of a radial load and an axial load) applied to the rolling bearing unit via a wheel. A structure for obtaining the load is described in Patent Document 2 and the like and has been conventionally known.

  Although FIG. 2 is not the structure itself described in this patent document 2, the conventional structure regarding the state quantity measuring apparatus of a rolling bearing unit which employ | adopts the same load measuring principle as the structure described in this patent document 2 is shown. The 1st example of is shown. In the first example of this conventional structure, a hub 4 that rotates together with a wheel is supported on a radially inner side of an outer ring 3 that is a stationary race ring that does not rotate even when used. 5 and 5 are rotatably supported. A preload is applied to each of the rolling elements 5 and 5 together with a contact angle of the rear combination type. In the illustrated example, a ball is used as the rolling element 5. However, in the case of an automobile bearing unit that is heavy, a tapered roller may be used instead of the ball.

  A cylindrical encoder 6 a is supported and fixed concentrically with the hub 4 at the axially inner end of the hub 4. A pair of sensors 8a and 8b are supported and fixed inside the bottomed cylindrical cover 7 that closes the inner end opening of the outer ring 3, and the detection portions of both the sensors 8a and 8b are connected to the encoder 6a. It is made to face and face the outer peripheral surface that is the surface to be detected. The encoder 6a is formed by combining a metal core 9 and an encoder body 10a. Of these, the metal core 9 is composed of a magnetic metal plate such as a mild steel plate and has a crank shape in cross section and is entirely formed in a stepped cylindrical shape. The encoder body 10a has a cylindrical magnetic member (permanent magnet material, high coercive force material) fixed to the entire circumference of the outer peripheral surface of the large-diameter side portion of the cored bar 9 (adhesion fixing, fixing by mold). Etc.) and then magnetizing the magnetic member.

  On the outer peripheral surface of the encoder main body 10a, which is the detection surface, portions magnetized in the S pole and portions magnetized in the N pole are arranged alternately and at equal intervals in the circumferential direction. . The boundary between the S pole and the N pole adjacent to each other in the circumferential direction gradually changes at a predetermined angle in a predetermined direction with respect to the axial direction of the outer peripheral surface. Further, the changing directions are opposite to each other in one half and the other half in the axial direction of the outer peripheral surface. Therefore, the portion magnetized in the S pole and the portion magnetized in the N pole have a “V” shape (or “<”) whose center in the axial direction protrudes most (or is recessed) in the circumferential direction. "".

  Further, magnetic detection elements such as a Hall IC, a Hall element, an MR element, and a GMR element are incorporated in the detection portions of both the sensors 8a and 8b. Of these two sensors 8a and 8b, the detection part of one sensor 8a is in one axial half of the outer peripheral surface of the encoder body 10a, and the detection part of the other sensor 8b is in the other axial half. They are close to each other. In the state where an axial load is not applied between the outer ring 3 and the hub 4, the axially central portion of the portion magnetized in the S pole and the portion magnetized in the N pole is the most in the circumferential direction. The installation position of each member in the axial direction is regulated so that the protruding portion exists just at the center position between the detection portions of the sensors 8a and 8b. In the same state, the circumferential positions of the sensors 8a and 8b are set so that the relationship between the detection portions of the sensors 8a and 8b and the phase of change of the outer peripheral surface of the encoder body 10a is as specified. Is regulated.

  In the state measuring device for a rolling bearing unit configured as described above, when an axial load is applied between the outer ring 3 and the hub 4, the phase in which the output signals of the sensors 8a and 8b change is shifted. That is, in the neutral state in which an axial load is not acting between the outer ring 3 and the hub 4 and the outer ring 3 and the hub 4 are not relatively displaced, the detection units of the sensors 8a and 8b are The outer peripheral surface of the encoder 6a is opposed to a portion shifted from the most protruding portion by the same amount in the axial direction. Therefore, the phases of the output signals of the sensors 8a and 8b are coincident or shifted by a predetermined value as determined by the predetermined relationship. On the other hand, when an axial load is applied to the hub 4 to which the encoder 6a is fixed, the detecting portions of both the sensors 8a and 8b have a magnitude of the axial load in a direction corresponding to the direction of the axial load. It faces the part shifted by the amount corresponding to. In this state, the phases of the output signals of the sensors 8a and 8b are shifted in the direction corresponding to the direction of the axial load by an amount corresponding to the magnitude of the axial load.

  As described above, in the case of the first example of the conventional structure described above, the phase of the output signals of the sensors 8a and 8b is such that the acting direction of the axial load applied between the outer ring 3 and the hub 4 (the outer rings 3). And the hub 4 are displaced in a direction corresponding to the axial direction of relative displacement). Further, the degree to which the phase of the output signals of the sensors 8a and 8b is shifted due to the axial load (relative displacement) increases as the axial load (relative displacement) increases. Therefore, the direction and magnitude of the relative displacement in the axial direction between the outer ring 3 and the hub 4 based on the presence and absence of the phase deviation of the output signals of the sensors 8a and 8b and the direction and magnitude of the deviation, if any. In addition, the direction and magnitude of the axial load acting between the outer ring 3 and the hub 4 can be obtained. The processing for calculating the relative displacement and load in the axial direction based on the phase difference existing between the output signals of the sensors 8a and 8b is performed by an arithmetic unit (not shown). For this reason, in the memory of this computing unit, the relationship between the phase difference and the relative displacement or load in the axial direction, which has been examined in advance by theoretical calculation or experiment, is stored in a form such as a calculation formula or a map. Let me.

  In the case of the above-described first example of the conventional structure, only one sensor set including a pair of sensors 8a and 8b in which the respective detection portions are opposed to the outer peripheral surface of the encoder body 10a is provided. On the other hand, Japanese Patent Application Nos. 2006-143097 and 2006-345849 disclose a structure in which a multi-directional displacement or external force is required by providing a plurality of sensor sets each composed of a pair of sensors. Yes.

  Next, FIG. 3 shows a second example of a conventional structure related to a state quantity measuring device for a rolling bearing unit. In the case of the second example of this conventional structure, the relative displacement in the radial direction between the outer ring 3 and the hub 4 or the radial load acting between the outer ring 3 and the hub 4 is measured. Yes. For this reason, in the case of this example, the encoder body 10b made of the permanent magnet constituting the encoder 6b is formed in a ring shape, and the detection portions of the pair of sensors 8a and 8b are located on the side surface in the axial direction of the encoder body 10b. The two positions are shifted in the radial direction. On the side surface in the axial direction of the encoder main body 10b, the S pole and the N pole whose shapes viewed from the axial direction are “V” shape or “<” shape are alternately arranged in the circumferential direction. For this reason, when the outer ring 3 and the hub 4 are relatively displaced in the radial direction based on the radial load, the phases of the output signals of the sensors 8a and 8b are shifted from the neutral position. And the relative displacement amount and radial load regarding the said radial direction are calculated | required by the mechanism similar to the case of the 1st example of the conventional structure mentioned above.

  In the first example of the conventional structure shown in FIG. 2 or the second example of the conventional structure described above, the pair of sensors 8a and 8b process the output signals of both the sensors 8a and 8b (waveform shaping or A sensor module 11 as shown in FIG. 4 is formed as an IC together with a processing circuit for calculating a phase difference. In such a sensor module 11, a plurality of (four in the illustrated example) terminals 12 and 12 are provided in addition to the sensors 8a and 8b and the processing circuit. Each of these terminals 12 and 12 has a function of taking out output signals of both the sensors 8a and 8b and supplying electric power to both the sensors 8a and 8b. The terminals 12 and 12 of the sensor module 11 have a plurality of conductors for sending the output signals of the sensors 8a and 8b to the calculator and supplying power to the sensors 8a and 8b. Connect the ends of the wires by soldering or brazing. And the said sensor module 11 is embedded in the predetermined position in the sensor holder 13 (refer FIGS. 2-3) made from a synthetic resin in the state which connected each said conductor to each said terminals 12 and 12 in this way, The sensor holder 13 is held and fixed at a predetermined position in the cover 7.

  As described above, the operation of embedding the sensor module 11 in the sensor holder 13 and holding the sensor holder 13 in the cover 7 sets the cover 7 in the cavity of the injection molding apparatus, This is performed by injection molding a synthetic resin in the cover 7 with the sensor module 11 held in a predetermined position in the cover 7. The terminals 12 and 12 and the conductors are previously brazed or soldered. If the sensor holder 13 is injection molded in this way and the sensor module 11 is held and fixed in the cover 7, the positions of the sensors 8a and 8b constituting the sensor module 11 can be regulated with high accuracy. . In particular, it is possible to reliably prevent the positions of both the sensors 8a and 8b from shifting after assembly. Even when the positions of both the sensors 8a and 8b are slightly deviated at the time of assembly, the state quantity calculation accuracy can be ensured by the initial setting of the arithmetic unit (adjustment of the zero point or gain).

  As described above, when the sensor holder 13 is injection-molded so as to hold and fix the sensor module 11 in the cover 7, the terminals 12, 12 are melted resin to be the sensor holder 13. Exposed to. On the surface of each of these terminals 12, 12, the brazing property or soldering property between these terminals 12, 12 and the respective conductors is improved (the brazing strength between these terminals 12, 12 and each conductor or A plating layer is provided for improving the soldering strength. Such a plating layer is formed of a metal having a melting point lower than that of the metal (copper or copper alloy) constituting each of the terminals 12 and 12. For example, when the terminals 12 and 12 and the conductors are soldered, the plating layer is formed of tin (Sn).

However, the melting point of tin is as low as about 232 ° C., and the plating layer is thinner than the soldered portion and has a very small heat capacity. For this reason, when a resin having a high melting point is used as the synthetic resin for constituting the sensor holder 13, the adjacent terminals 12 and 12 may be short-circuited (short-circuited) by tin. For example, taking the sensor module 11 shown in FIG. 4 as an example, the pitch P ₈ between the sensors 8a and 8b is 2.5 mm, and the pitch P 12 between the terminals 12 and ₁₂ is 1.27 mm. It can be considered that the width W 12 of the terminals 12 and ₁₂ is designed to be about 0.8 mm. In this case, the distance D12 between the adjacent terminals 12, ₁₂ is 0.47 mm. In this way, in the situation where the distance D 12 between the adjacent terminals 12 and ₁₂ is narrow, if the tin constituting the plating layer on the surface of each of the terminals 12 and 12 is softened or melted, there is a possibility that the short circuit will occur. is there.

  That is, the tin is softened or melted by the heat of the molten resin fed into the mold cavity to form the sensor holder 13, and the tin is pushed by the flow of the molten resin, for example, There is a possibility of concentrating on the base of each of the terminals 12 and 12 (upper part of FIG. 4) and projecting to the side (lateral direction of FIG. 4). In this manner, when the tin constituting the plating layer on the surface of each of the terminals 12 and 12 is projected in the direction of the adjacent terminals 12 and 12, the tips of the projected tin are brought into contact with each other, and the short circuit is caused. May occur. Since the unit embedding the sensor module 11 in which the terminals 12 and 12 are short-circuited must be discarded as a defective product, which causes an increase in cost due to yield deterioration, improvement is desired.

JP 2004-36863 A JP 2006-1113017 A

  The state quantity measuring apparatus for a rolling bearing unit according to the present invention realizes a structure in which a plating layer on a terminal surface is not softened or melted during injection molding of a synthetic resin sensor holder in view of the above-described circumstances. Invented accordingly.

The state quantity measuring device of a rolling bearing unit which is an object of the present invention includes a rolling bearing unit and a state quantity measuring device.
Of these, the rolling bearing unit has an outer ring that has a double row outer ring raceway on its inner peripheral surface and does not rotate during use, a hub that has a double row inner ring raceway on its outer peripheral surface and rotates during use, A plurality of rolling elements are provided between the inner ring raceway in the row and the outer ring raceway in the both rows so as to be capable of rolling plurally for each row.
The state quantity measuring device includes an encoder, at least one sensor, and a calculator.
Of these, the encoder is supported and fixed concentrically with the hub at the end of the hub, and has a cylindrical or annular detection surface concentric with the hub. It is changed alternately in the circumferential direction.
Further, the sensor is placed in a metal-made bottomed cylindrical cover that is fixed to this end portion so as to close the end opening of the outer ring with the detection portion facing the detection surface of the encoder. It is held via this sensor holder in a state of being embedded in a sensor holder made of synthetic resin. And an output signal is changed corresponding to the characteristic change of the said to-be-detected surface.
Further, the computing unit is based on an output signal of the sensor, and includes a rotation speed of the hub, a relative displacement between the outer ring and the hub, and an external force acting between the outer ring and the hub. It has a function of calculating at least one kind of state quantity.
Furthermore, the ends of a plurality of conductors for sending the output signal of the sensor to the computing unit are connected to a plurality of terminals provided on the sensor and plated on each surface by brazing or soldering. is doing.

In particular, in the state quantity measuring apparatus for a rolling bearing unit according to the present invention, the metal plated on the surface of each terminal is tin or an alloy of tin and lead. The synthetic resin constituting the sensor holder is PBT or PA. Furthermore, when the melting temperature of the synthetic resin constituting the sensor holder is T _P ° C. and the melting temperature of the metal plated on the surface of each terminal is T _M ° C., to satisfy T _P ≦ T _M +50 , A combination of the metal and the synthetic resin.
That is, having such a relationship, as the synthetic resin for metal and the sensor holder injection molding for plating, to adopt either of the following such combinations.
[First example]
Metal: Tin Synthetic resin: PBT (Melting point: 250-270 ° C.)
[Second example]
Metal: Tin Synthetic resin: PA (Melting point: 200-270 ° C.)
[Third example]
Metal: Alloy of tin and lead (Pb) (solder, melting point: 182-232 ° C.)
Synthetic resin: PA (melting point: 200-270 ° C.)
[Fourth example]
Metal: Alloy of tin and lead (Pb) (solder)
Synthetic resin: PBT

According to the state quantity measuring device of the rolling bearing unit of the present invention configured as described above, it is possible to suppress the plating layer on the terminal surface from being softened or melted during the injection molding of the synthetic resin sensor holder, and adjacent to each other. A structure capable of preventing the terminals from being short-circuited can be realized.
That is, when injection molding the sensor holder, when the synthetic resin melted into the cavity of the mold is fed through the gate, the temperature of the synthetic resin at the gate portion is higher than the melting point of the metal constituting the plating layer. Even if it is higher, the temperature of the synthetic resin drops rapidly and falls below this melting point. Therefore, if measures such as installing the gate in a part away from the sensor (sensor module) are taken, the temperature of the synthetic resin in the state reaching the sensor is lower than the melting point of the metal constituting the plated layer. Become. For this reason, this plating layer can be prevented from being softened or melted, and adjacent terminals can be prevented from being short-circuited.

  A feature of the present invention is that the relationship between the melting point of the synthetic resin constituting the sensor holder and the melting point of the metal constituting the plating layer covering the surface of the terminal provided in the sensor module is regulated. The overall structure of the state quantity measuring device for the rolling bearing unit including the encoders 6a and 6b and the sensors 2a and 2b is the same as that of the conventional structure shown in FIGS. Since the structure is the same as the structure shown in FIG. 4 described above, description of equivalent parts is omitted.

  The present invention is not limited to a structure for obtaining a relative displacement amount, an axial load, or a radial load in the axial direction based on a phase difference existing between output signals of a pair of sensors arranged apart in the axial direction. it can. For example, the inclination of the encoders of a pair of sensors arranged at two positions on the opposite side in the radial direction can be implemented with a structure for obtaining a moment and an axial load based on a phase difference existing between output signals. Alternatively, a structure in which the relative displacement amount or the axial load in the axial direction is obtained based on the duty ratio of the output signal of one sensor can be implemented. Furthermore, a structure provided with a rotational speed sensor for ABS control can also be implemented.

The partial schematic sectional drawing which shows two examples of the basic structure of the state quantity measuring apparatus of the rolling bearing unit used as the object of this invention. Sectional drawing which similarly shows the 1st example of a specific structure. Sectional drawing which similarly shows the 2nd example. FIG. 3 is a plan view showing an example of a sensor module in which a pair of sensors and a processing circuit are integrated into an IC as viewed from the vertical direction in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Encoder 2a, 2b Sensor 3 Outer ring 4 Hub 5 Rolling element 6a, 6b Encoder 7 Cover 8a, 8b Sensor 9 Core metal 10a, 10b Encoder main body 11 Sensor module 12 Terminal 13 Sensor holder

Claims (1)

A rolling bearing unit and a state quantity measuring device;
Of these, the rolling bearing unit has an outer ring that has a double row outer ring raceway on its inner peripheral surface and does not rotate during use, a hub that has a double row inner ring raceway on its outer peripheral surface and rotates during use, Between the inner ring raceway of the row and the outer ring raceway of the two rows, a plurality of rolling elements provided so as to be freely rollable for each row are provided.
The state quantity measuring device includes an encoder, at least one sensor, and a computing unit,
Of these, the encoder is supported and fixed concentrically with the hub at the end of the hub, and has a cylindrical or annular detection surface concentric with the hub. It is changed alternately in the circumferential direction,
In the state where the detection unit is opposed to the detection surface of the encoder, the sensor is provided with a synthetic resin in a metal bottomed cylindrical cover fixed to the end to close the end opening of the outer ring. In an embedded state in a sensor holder, is held through this sensor holder, and changes the output signal in response to a change in the characteristics of the detected surface,
The computing unit is based on the output signal of the sensor, among the rotational speed of the hub, the relative displacement between the outer ring and the hub, and the external force acting between the outer ring and the hub, It has a function to calculate at least one kind of state quantity,
The ends of a plurality of conductors for sending the output signal of the sensor to the computing unit are connected to a plurality of terminals provided on the sensor and plated on each surface by brazing or soldering. In the state quantity measuring device of the rolling bearing unit,
The metal plated on the surface of each terminal is tin or an alloy of tin and lead, and the synthetic resin constituting the sensor holder is PBT or PA,
When the melting temperature of the synthetic resin constituting the sensor holder is T _P ° C. and the melting temperature of the metal plated on the surface of each terminal is T _M ° C. , the above metal is satisfied so that T _P ≦ T _M +50 is satisfied. A state quantity measuring device for a rolling bearing unit characterized by combining the above and the above synthetic resin .

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