GB2128337A - Rotation detector - Google Patents

Abstract

A rotary member (1) carries magnets (3) and has a plurality of spaced mount openings (4,4a) to permit the rotary member to be attached, by means of mount elements (13, 14) in selected openings (4, 4a) to the spokes (15) of any one of various different spoked wheels, and concentrically of the hub (2). A magnetic flux sensor (5) is clamped to the hub by an adjustable clamp means (9, 10, 12) in a position spaced transversely from the rotary member so that in use the sensor senses passage of each magnet past the sensor. The detector can thereby be readily installed in a correct working position on various spoked wheels. <IMAGE>

Description

SPECIFICATION Attachment of a rotation detector to a spoked wheel The present invention relates to the attachment of a rotation detector, for example an r.p.m.

(revolutions per minute) detector, to a spoked wheel, for example of a bicycle, an autocycle and the like.

In Japanese Utility Model Appiication No.

55-181334 the present Applicant discloses a revolutions per-minute detector comprising a rotary member having a plurality of magnets concentrically arranged therein, said rotary member being attached to a portion of a wheel, a detector fixed in a place in such a manner that it faces said plurality of magnets, said detector having a magnetic flux sensing section comprised of at least a lead switch and a resistance, and an operational display for receiving a pulse signal from said detector and indicating digitally the revolutions per minute.

An object of the present invention is to provide an interchangeable arrangement which permits easy and rapid attachment and adjustment of a rotary member and a sensor to a spoked wheel, and its hub, of any wheel of a number of mutually different spoked wheels, without requiring additional fittings.

According to the present invention them is provided a detector adapted to respond to the rotation of a spoked wheel, said detector comprising a rotary member carrying at least one magnetic element and having a plurality of spaced mount openings therein to permit the rotary member to be attached, by means of mounting elements associated with at least some of said mount openings, to the spokes of any wheel of a number of mutually different spoked wheels and concentrically of the hub of that wheel, and a magnetic flux sensor having an adjustable clamping means to permit the sensor to be clamped to the hub of that said wheel and adjusted to a position spaced from the rotary member so that in use said sensor senses passage past the sensor of the or each said magnetic element.

An embodiment of the invention will now be described, by way of exampie, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a detector according to the present invention, shown attached to a wheel; Figure 2 is a sectional view taken along the line A-AofFigure 1; Figure 3 is a partially sectioned plan view showing the mount plate of the sensor; Figure 4 is a partially cut away front view showing the rotary member; Figure 5 is a sectional view taken along the line B-B of Figure 4; Figure 6 is a sectional view taken along the line C-C of Figure 4; Figure 7 is a sectional view taken along the line D-D of Figure 1; and Figure 8 is an exploded perspective view of the sensor.

Referring now to Figure 1, a rotary member 1 is formed by putting two annular plates 1 a and 1 b together, each molded of a non-magnetic synthetic resin material. As will be seen from Figure 1, the rotary member 1 is mounted concentrically around a hub 2 of a bicycle wheel for co-rotation therewith, and carries a plurality of circumferentially spaced magnetic elements 3.

The rotary member 1 is also provided concentrically with a plurality of mount openings 4 and 4a, to permit the rotary member to be mounted, by means of mounting elements associated with at least some of said mount openings, to any one of a variety of wheels without eccentricity (36-spoke wheels and 28spoke wheels are generally used depending upon the size of the bicycle), i.e., concentrically of the hub of that wheel.

It will be noted from Figure 4 that, with a 36spoke wheel, three mount openings 4 disposed concentrically at equal angles of 1200 may be used for mounting, and, with a 28-spoke wheel, one mount opening 4 and two concentric openings 4a may be used. In the latter use, an angle b between a line extending through the opening 4 and the center of the circle and a line extending through one opening 4a and the center of the circle is 102.860, while an angle c between two lines running through the two openings 4a and the center of the circle is 1 54.280. The present invention is not limited to the abovementioned arrangements although they are preferred.

Referring to Figure 2 a sensor 5 is molded of a synthetic resin material with a built-in magnetic flux sensor S comprising a lead switch, a resistance and other elements. The sensor responds when it enters the magnetic field of each magnetic element 3, and sends the resulting pulse signal via a conductor 6 to an operational display (not shown) attached to a handle bar. The detector 5 has at one end a sliding projection 7. A bifurcated mount plate 8 is detachably clamped onto the hub 2 of the wheel by a clamp screw 9.

The sliding projection 7 of the detector 5 is slidingly inserted into a groove 7a formed in an adjuster 10 and is movable along the groove, against the action of a coil spring 11, by an adjusting screw 1 2 engageable with an internally threaded member 12a.

The rotary member 1 is attached to a spoke 1 5 by means of a mount screw 14 and a mount piece 1 3 having a bore, through which the spoke passes, in such a manner that it is positioned concentrically around the hub 2. Making use of the mount plate 8 of the detector 5, the detector 5 is clamped onto the hub 2 with the magnetic flux sensor S spaced away from the magnetic element 3 by a desired spacing. The distance between the sensor S and the magnetic element 3 may be different depending upon the material and thickness of the sensor S and the strength of the magnets 3, and may usually be in the range 2 to 3 mm since too large or small a spacing can result in malfunction or failure. Heretofore, the adjustment of the spacing has been effected by experts.

According to the present invention, the detector 5 can be adjusted by insertion or loosening of the adjustment screw 12 of the adjustor 10 by a simple tool such as a wrench or the like, without recourse to experts. In addition, there is no fear that the spacing may vary due to vibration, since the sliding projection 7 and the adjustor 10 are supported by the resiliency of the coil spring 11.

The maximum spacing adjustment range is about 4 mm or more depending upon the size and shape of the sliding part.

As will be seen from Figure 3, the mount plate 8 may be formed with a step 8a of a suitable size.

If the limit of the sliding adjustment range is reached, the plate 8 is turned over and reclamped, thereby providing a discrete adjustment by a distance d (Figure 3). The addition of such a step enables, in association with the fine continuous adjustment of the screw 12, any one to mount and adjust easily the present arrangement without recourse to any particular tool or part. In addition, the present sensor arrangement is adjustably positioned within the magnetic field of elements 3 so that precise and stable detection of the magnetic flux can invariably be effected. Furthermore, the present arrangement is inexpensive to mass-produce owing to its simple structure, and can interchangeably be fitted to various wheels.

Claims (4)

1. A detector adapted to respond to the rotation of a spoked wheel, said detector comprising a rotary member carrying at least one magnetic element and having a plurality of spaced mount openings therein to permit the rotary member to be attached, by means of mounting elements associated with at least some of said mount openings, to the spokes of any wheel of a number of mutually different spoked wheels and concentrically of the hub of that wheel, and a magnetic flux sensor having an adjustable clamping means to permit the sensor to be clamped to the hub of that said wheel and adjusted to a position spaced from the rotary member so that in use said sensor senses passage past the sensor of the or each said magnetic element.

2. A detector according to claim 1 wherein said clamping means comprises a projection slidable in a groove of a grooved member, means for securing the projection in any said adjusted position along said groove, and a hub mount plate detachably secured to said grooved member.

3. A detector according to claim 2 wherein said mount plate is formed with a step and is adapted for attachment in either of two orientations relative to said grooved member, whereby to provide for a discrete adjustment in said spacing of said rotary member and said sensor.

4. A detector adapted to respond to the rotation of spoked wheel, said detector being substantially as described herein with reference to the accompanying drawings.