JPH1123600A5 - - Google Patents

Description

In the rolling bearing unit with rotational speed detection device of the present invention configured as described above, the cover 18c to which the seal ring 19b is coupled and supported can be attached to the outer ring 1a, and the encoder 23 can be attached to the second inner ring member 5a, prior to assembly of the rolling bearing unit. That is, with the cover 18c to which the seal ring 19b is coupled and supported attached to the outer ring 1a and the encoder 23 fitted and fixed to the middle portion of the second inner ring member 5a, the first and second inner ring members 4a, 5a can be inserted inside the outer ring 1a with a plurality of rolling elements 12, 12 interposed therebetween. After insertion, the inner ring members 4a, 5a are joined together by crimping the tip ends of the cylindrical portions 9a outward in the diametrical direction and further by welding 17a to form the hub 6a, and the hub 6a can be rotatably supported inside the outer ring 1a. The work of attaching the cover 18c, which connects and supports the seal ring 19b, to the outer ring 1a and the work of attaching the encoder 23 to the second inner ring member 5a can be performed with the outer ring 1a and the second inner ring member 5a in a state where they are individual components, so the attachment work of the encoder 23 and the cover 18c can be easily performed. The work of attaching the sensor unit 47 to the outer ring 1a is performed after the assembly work of the rolling bearing unit is completed. Therefore, the part of the tip of the sensor unit 47 that protrudes from the inner surface of the outer ring 1a does not interfere with the assembly work.

The permanent magnet 53 is fixed to the outer peripheral surface of the small-diameter portion 55 by suitable means, such as external fitting by interference fit, adhesive bonding, or baking. The permanent magnet 53 is magnetized along the diameter. The magnetization direction alternates and changes at equal intervals along the circumferential direction. Therefore, south and north poles are alternately and equally spaced on the outer peripheral surface of the permanent magnet 53. When such a permanent magnet 53 faces the detection surface of the sensor unit 47 across the minute gap 48, the direction of magnetic flux flowing through the magnetic detection element provided in the sensor unit 47 changes at a frequency proportional to the rotational speed of the encoder 23a, thereby enabling detection of the rotational speed. In this example, when the permanent magnet 53 is held and fixed to the outer peripheral surface of the small-diameter portion 55, the outer diameter of the permanent magnet 55 is equal to or smaller than the diameter of the sliding portion between the leading edge of the seal lip 41 and the mating surface, i.e., the outer peripheral surface of the large-diameter portion 56. Therefore, in the case of this example as well, the cover 18c to which the seal ring 19b is coupled and supported can be attached to the outer ring 1a, and the encoder 23a can be attached to the second inner ring member 5a, prior to assembling the rolling bearing unit, so that the attachment work of the encoder 23a and the cover 18c can be easily carried out. The other configurations and operations are the same as in the first example described above, so duplicated explanations will be omitted.

Next, FIG. 5 shows a fourth embodiment of the present invention, also corresponding to claim 2. In this embodiment, the encoder 23c uses a ring-shaped permanent magnet 53a, such as a rubber magnet, attached to the inner surface of the ring portion 61 of the retaining ring 60 by adhesive bonding, baking, or its own magnetic attraction. The permanent magnet 53a is magnetized in the axial direction (left-right direction in FIG. 5). The magnetization direction alternates circumferentially at equal intervals. Therefore, the inner surface of the permanent magnet 53a has alternating south and north poles arranged at equal intervals. In this embodiment, an insertion hole 46a for mounting the sensor unit 47 is formed directly in the inner end of the outer ring 1a. Unlike the third embodiment, the cover 18d (FIG. 4) is not provided. Accordingly, the leading edge of the seal lip 41a of the seal ring 19c is in sliding contact with the inner end face and the inner end of the inner peripheral surface of the outer ring 1a. The outer diameter _D60 of the retaining ring 60 is smaller than the inner diameter _R1a of the inner end of the outer ring 1a ( _D60 ≦ _R1a ), allowing the encoder 23c to be inserted inside the inner end of the outer ring 1a. Therefore, in this example, the seal ring 19c and the encoder 23c can be attached to the second inner ring member 5a prior to assembly of the rolling bearing unit, facilitating the installation of the seal ring 19c and the encoder 23c . Other configurations and functions are similar to those of the third example described above, and therefore redundant explanations will be omitted. When implementing the present invention, the types of sensors and encoders are not limited to magnetic types as shown. Sensors and encoders constituting rotational speed detection devices of other structures, such as eddy current types, can also be used.