Wheel speed detecting device

Abstract: PROBLEM: To provide an art capable of enhancing the detection accuracy of a wheel speed detecting device and reducing cost. SOLUTION: The wheel speed detecting device (50) for the rear wheel comprises the pulsar ring (52) mounted on the rear wheel hub (18), and a pulse counting sensor (60) mounted on the swing arm (35). The pulsar ring (52) comprises the disc (55), and the pulse detecting holes (57) formed at a predetermined pitch on a pitch circle drawn at a radially inward circumferential position spaced at a predetermined distance from the outer edge of the disc (55). EFFECT: The pulse detecting hole is formed in a position on the center side apart from the outer edge of the pulsar ring, leaving the outer edge of the pulsar ring in a circular form. It is, therefore, possible to prevent warpage of the pulsar ring by the outer edge portion if the pulse detecting holes are made by pressing.

Description: Industrial Field of Utilization This invention relates to a wheel speed detecting device which detects the rotational speed of a wheel according to the preamble part of claim 1. Prior Art Motorcycles adopting for instance the Antilock Brake System (ABS) are equipped with a wheel speed detecting device for detecting the rotational speed of front and rear wheels. As a prior art wheel speed detecting device of the generic kins, the "Wheel Speed Detecting Device in Motorcycles" disclosed in Japanese Patent Laid-Open No. JP H8-133154A has been known. This prior art will be explained in detail by referring to Fig. 18. Fig. 18 is a side view of a prior art wheel speed detecting device. The wheel speed detecting device mounted on the rear wheel of a motorcycle will be explained below. In a wheel speed detecting device 150, a sensor ring (hereinafter referred to as the "pulser ring") 154 is attached on a spoke portion 152 of a rear wheel 151; and a pulse counting sensor 156 (e.g., an electromagnetic rotary sensor) is attached on a swing arm 155 which supports the rear wheel 151, oppositely to teeth 154 of the pulser ring 153. According to the wheel speed detecting device 150, with the rotation of the rear wheel 151, the pulser ring 153 also rotates together with the rear wheel 151, while the teeth 154 of the pulser ring 153 are passing the pulse counting sensor 156. The pulse counting sensor 156 counts the teeth 154 that have passed, thus detecting the wheel speed of the rear wheel 151 (the rotational speed of the rear wheel 151). To improve the detection accuracy of the teeth 154 by the pulse counting sensor 156, it is desirable to mount the pulse counting sensor 156 close to the teeth 154. To mount the pulse counting sensor 156 close to the teeth 154, it is necessary to set the flatness of the pulser ring 153 (particularly, the teeth 154). In case the flatness of the pulser ring 153 exceeds the permissible range, unevenness of the pulser ring 153 increases. It is, therefore, necessary set the pulse counting sensor 156 apart from the teeth 154 with the unevenness taken into account. The detection accuracy of the teeth 154 is hard to improve by the pulse counting sensor 156. The teeth 154 of the pulser ring 153, therefore, have been formed by a cutting process to set the flatness of the pulser ring 153 (especially the teeth 154 ) within the permissible range. The processing of the pulser ring 153 needs time and labor, becoming a factor for increasing the cost. Forming the pulser ring 153 by pressing is also considered. However, because the teeth 154 are relatively long and slender, the pulser ring 153, if processed by pressing, the teeth 154 will be subject to warpage. Therefore, it is necessary to correct the warpage of the teeth 154 after pressing the pulser ring 153, which, however, makes much time and labor, resulting in a factor for increasing cost. It, therefore, has been desired to put into practice a wheel speed detecting device capable of enhancing the detecting accuracy and lower cost. Document JP 10185936 A deals with the problem of providing a wheel speed sensor for a motorcycle having an excellent maintainability, in particular with regard to a wheel that can be loaded or unloaded without interference with the speed sensor. The construction off the wheel speed device of document JP 10185936 A is very much the same as that of document JP 08133154 A, i.e. the sensor is provided radially spaced apart from a cylindrical pulser ring that has axially extending slots or recesses. Document JP 10185936 A neither mentions any stiffening ribs projecting towards the pulse sensor nor discloses providing a stiffening rib adapted to radially cover the detecting surface of the pulse counting sensor. Document US-A-4 795 278 discloses a wheel speed detecting device according to the preamble of claim 1. It is an object of the invention to provide an art which can enhance the detecting accuracy of the wheel speed detecting device and lower the cost. In more detail, it is the object of the present invention to prevent the pulser ring from warping and further to protect the wheel speed detecting device from damage caused by objects occasionally entering the gap between a detecting surface of the pulse counting sensor and the pulser ring. This object is attained by a wheel speed detecting device exhibiting all features of claim 1. The wheel speed detecting device according to a first aspect of the invention comprises a pulser ring attached on the wheel side and a pulse counting sensor attached on the vehicle body side. The pulser ring comprises a disc, and pulse detecting holes or pulse detecting recesses provided at a predetermined pitch on a pitch circle drawn in a radially inward circumferential position spaced at a distance from an outer edge of the disc. The pulse detecting hole is opened in a position on the center side off from an outer edge of the pulser ring, whereby the outer edge of the pulser ring can be left in a circular shape. Therefore, it is possible to restrain the warpage of the pulser ring by the outer edge if the pulse detecting hole is formed by pressing. The flatness of the pulser ring, therefore, can be held within the permissible range. The disc has a sensing surface on the side directed toward the pulse counting sensor. A stiffening rib is provided in the vicinity of the sensing surface. The sensing surface can be increased in rigidity by providing the stiffening rib in the vicinity of the sensing surface. Therefore, if the pulser ring is set to a little plate thickness, it is possible to hold the flatness of the sensing surface within the permissible range, thereby enabling reduction of pulser ring weight. The stiffening rib is provided along the sensing surface, and the height of this stiffening rib is set larger than the clearance from the sensing surface to the pulse counting sensor. The stiffening rib is provided along the sensing surface and the height of this stiffening rib is increased larger than the clearance from the sensing surface to the pulse counting sensor. Therefore, it is possible to cover the clearance between the sensing surface and the pulse counting sensor with the stiffening rib; the stiffening rib being usable as the protective cover. Therefore, the clearance between the sensing surface and the pulse counting sensor is protected by the stiffening rib, so that the clearance can be prevented from biting a flying substance such as a flying rock. Furthermore, since the stiffening rib is usable as a protective cover, no individual protective cover is needed, thereby preventing an increase in component count and furthermore time and effort for installing the protective cover can be dispensed with. The stiffening rib may be formed by bending the outer edge of the disc. The wheel speed detecting device can be improved in quality by increasing the rigidity of the pulser ring with the outer edge of the disc bent. Furthermore, the pulser ring of predetermined thickness, being usable, can be decreased in weight, making it possible to decrease cost and to improve vehicle performance. In an advantageous embodiment of the present invention, the pulser ring may be prepared from a pressed part with punched pulse detecting holes; and where one of both sides of the pulser ring which faces to a punch is called the first side and the other is the second side, the pulser,ring is attached so that the second surface will face the pulse counting sensor. When the pulse detecting hole is punched from the first side though to the second side, the edge of the hole in the first side becomes round, while the hole in the second side has a sharp edge. In the advantageous embodiment, therefore, the pulser ring is attached with the second side having sharp-edge holes directed toward the pulse counting sensor. By using the pulses ring having the sharp-edge holes, the sensing performance of the pulse counting sensor can be improved. An embodiment of the present invention with the above-described configuration has the following advantages. The pulse detecting holes are formed in a radially inward position apart from the outer edge of the pulser ring, and therefore the outer edge of the pulser ring can be left in a circular form. Therefore, it is possible to prevent pulser ring warpage by the outer edge if the pulse detecting hole is made by pressing. Consequently, the flatness of the pulser ring can be kept within the permissible range, thereby lowering the pulser ring cost. Furthermore the flatness of the pulser ring that can be kept within the permissible range, the detecting accuracy of the wheel speed detecting device can be enhanced. The rigidity of the sensing surface can be increased by forming the stiffening rib in the vicinity of the sensing surface. Consequently, it is possible to keep the flatness of the sensing surface within the permissible range if the plate thickness of the pulser ring is set small, and accordingly to reduce the weight of the pulser ring. Furthermore, because the flatness of the pulser ring can be kept within the permissible range, the detecting accuracy of the wheel speed detecting device can.be improved. Furthermore, the stiffening rib is provided along the sensing surface; and the stiffening rib has been increased in height larger than the distance from the sensing surface to the pulse counting sensor. Therefore, the clearance between the sensing surface and the pulse counting sensor can be covered with the stiffening rib, which is usable as a protective cover. Therefore, since the clearance between the sensing surface and the pulse counting sensor is protected with the stiffening rib, it is possible to prevent entrance of a flying substance, such as a flying rock, into the clearance, and accordingly to enhance the detecting accuracy of the wheel speed detecting device. Furthermore, because the stiffening rib is usable as a protective cover, no separate protective cover is needed; and therefore it is possible to prevent an increase in the component count, to dispense with protective cover installation, and therefore to lower cost. Still further, the outer edge of the disc is bent to increase the rigidity of the pulser ring, thereby improving disc quality and enabling wheel speed detection accuracy. Furthermore, it is possible to prevent an increase in the plate thickness of the pulser ring by increasing the rigidity of the pulser ring. Consequently, cost reduction and enhanced vehicle performance are realized by reducing the weight of the pulser ring. When the pulser ring is punched through from the first surface to the second surface, the edge portion of the punched hole in the first surface becomes round, while the edge portion of the punched hole in the second surface becomes sharp. Therefore, the pulser ring is preferably placed with the second surface having the sharp edge facing toward the pulse counting sensor. In the case of the pulser ring having the sharp, square edge hole, the sensing performance of the pulse counting sensor can be improved. As a result, it is possible to enhance the detecting accuracy of the wheel speed detecting device. Preferred Embodiments An embodiment of the invention will be explained with reference to the accompanying drawings. In the drawings, the "front", "rear", "left", "right", "upper" and "lower" designations refer to the orientation of the motorcycle in relation to the driver when sitting normally in the driver's seat. The drawings are to be viewed in the direction of reference numerals. Figs. 13a and b as well as 17b show an embodiment of the present invention. The remaining figures refer to prior art (Figs. 7c, d; 10a; 17a;. 18) or to alternative constructions of a wheel speed detecting device which are not covered by independent claim 1, but which show individual features that might be realized also in a wheel speed detecting device of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a left side view of a motorcycle carrying a wheel speed detecting device according to the invention; Fig. 2 is a plan view of a motorcycle with a wheel speed detecting device mounted to the. rear wheel, which is not covered by claim 1; Fig. 3 is an enlarged view of the section 3 in Fig. 2; Fig. 4 is a sectional view taken along line 4-4 of Fig. 2; Fig. 5 is an exploded perspective view of the wheel speed detecting device for the rear wheel, which is not covered by claim 1; Fig. 6 is a view explaining the method of fabricating a pulser ring of a wheel speed detecting device for the rear wheel, which is not covered by claim 1; Fig. 7 is a view explaining a pulser ring of a wheel speed detecting device for the rear wheel, which is not covered by claim 1; Fig. 8 is a side view of a wheel speed detecting device for the front wheel of the invention; Fig. 9 is a sectional view of a wheel speed detecting device mounted on the rear wheel, which is not covered by claim 1. Fig. 10 is an explanatory view of rigidity of a wheel speed detecting device, which is not covered by claim 1; Fig. 11 is a sectional view of a wheel speed detecting device mounted on the rear wheel, which is not covered by claim 1; ; Fig. 12 is a sectional view of the wheel speed detecting device mounted on the rear wheel, which is not covered by claim 1; Fig. 13 is a sectional view of the wheel speed detecting device of the invention mounted on the rear wheel; Fig. 14 is a sectional view of the wheel speed detecting device mounted on the rear wheel, which is not covered by claim 1; Fig. 15 is a sectional view taken along line 15-15 of Fig. 14; Fig. 16 is an explanatory view of a fabricating process usable for the wheel speed detecting device of the invention; Fig. 17 is an explanatory view of operation of the wheel speed detecting device according to a preferred .embodiment of the invention; Fig. 18 is a side view of a conventional wheel speed detecting device. Fig. 1 is the left side view of a motorcycle of the invention. The motorcycle 10 is a scooter-type vehicle comprising such prime constituents as a vehicle frame 11, a front fork 13 attached to a head pipe 12 of the vehicle frame 11, a front wheel 14 attached on the front fork 13, a handlebar 15 connected to the front fork 13, a swing unit 16 (engine 16a and transmission 16b) attached on the rear upper part of the vehicle frame 11, a rear wheel 17 attached on the rear part of the swing unit 16, a seat 19 mounted on the rear upper part of the vehicle frame 11, and a body cover 20 covering the vehicle frame 11. The body cover 20 comprises a front cover 21 covering the front part of the head pipe 12 and the upper part of the front wheel 14, an inner cover 22 covering the rear part of the front cover 21, right and left floor steps 23 (only the left floor step 23 is shown in Fig. 1 and the following) as low-floor type foot rests for the driver, right and left floor skirt 24 extended downward from the outer edge of the floor step 23, an under cover 25 covering the lower edge of the floor skirt 24, a center cover 26 extended to the rear from the inner cover 22 to cover the central part in the longitudinal direction of the vehicle frame 11, and a side cover 27 extended to the rear from the center cover 26 to cover both sides of the rear part of the vehicle frame 11. In the drawing, reference numeral 28 denotes a hydraulic front disc brake; 29a, a front fender; 29b, a headlight; 29c, a windshield; 29d, a handle cover; 29e, a handle grip; 29f, a mirror; 29g, a fuel tank; 29h, an engine cooling radiator; 29j, a foldable bar step for a rear seat passenger; 29k, a main stand; 29m, an air cleaner,; 29n, a taillight; 29p, a rear fender; 29q, a storage box; 29s, rear brake operating member; and 29t, a rear suspension. Fig. 2 is a plan view of a motorcycle with a wheel speed detecting device that does not embody the present invention mounted on the rear wheel. The left rear part of the swing unit 16, that is, the left rear part 32 of the transmission case 31, on the left side of the vehicle centerline (CL) (the center of vehicle width) extends to the rear along the vehicle CL. Therefore, the left rear part 32 of the transmission case 31 is extended longer to the rear than the right rear end part 33. In this drawing, the swing arm 35 is attached at the front part by a bolt 36 midway in the longitudinal direction of the swing unit 16, that is, at the right rear end part 33 of the transmission case 31; the swing arm 35 is extended to the rear, so that a rear axle 37 is rotatably supported by the left rear part 32 of the transmission case 31 and the rear part of the swing arm 35; and the rear wheel 17 is mounted to the rear axle 37. As a result, the rear wheel 17 can be supported between the rear part of the swing unit 16 and the rear part of the swing arm 35. Reference numeral 46 denotes a muffler; 47, a bolt; and 48, a bracket. At the rear part of the motorcycle10 are mounted a rear brake 40 and a wheel speed detecting device 50 (for the rear wheel). The rear brake 40 is a hydraulic rear disc brake comprising a disc-like brake disc 41 bolted to the right side of a hub 18 of the rear wheel 17, and a caliper 42 bolted to the swing arm 35. for brake control of the brake disc 41. The wheel speed detecting device (for the rear wheel) 50 comprises a pulser ring 52 bolted to the right side of the wheel side (the hub 18 of the rear wheel 17), and a pulse counting sensor 60 bolted to the vehicle body side (the swing arm 35). The wheel speed detecting device (for the rear wheel) 50 will now be described in detail. Fig. 3 is an enlarged view of the section 3 in Fig. 2, that is, a sectional view of the wheel speed detecting device (for the rear wheel) of Fig. 2. The wheel speed detecting device (for the rear wheel) 50 functions to count pulse detecting holes 57 made in the pulser ring 52 by means of the pulse counting sensor 60, and to detect the rotational speed (wheel speed) of the rear wheel 17 (shown in Fig. 2). The pulser ring 52 is comprised of a cylindrical portion 53 which can be fitted in the recess portion 18a of the hub 18, a seat plate 54 formed on the bottom the cylindrical portion 53, a disc 55 formed on the top of the cylindrical portion 53, pulse detecting holes 57 made at predetermined pitches near the center of a predetermined distance from the outer edge 56 of the disc 55 (see Fig. 4 also) , and a bent portion (hereinafter referred to as the "bent portion 56") formed by bending the outer edge. 56 of the disc 55 The pulser ring 52 has four bolt holes 54a made in the seat plate 54, and is installed to the recess portion 18a of the hub 18 by inserting the bolts 59 into the bolt holes 54a and tightening the bolts 59 into the hub 18. The hub 18 is positioned properly in a predetermined position in the direction of vehicle width in order to position the rear wheel in a predetermined position in the direction of the wheel width. Therefore, the pulser ring 52 can readily be located in a desired position in the direction of the vehicle width by mounting the pulser ring 52 in the recess portion 18a of the hub 18. The pulser ring, therefore, can be installed in a short time. The pulse counting sensor 60 is an electromagnetic rotary sensor, including a body 62 inserted into a mounting hole 35b of the swing arm 35, and an overhanging plate 63 extended unitarily from the body 62 and pressed against the swing arm 35 by the bolts 65, 65. The detecting portion 62a of the pulse counting sensor 60 can be mounted at a predetermined spacing δ correspondingly to the pulse detecting holes. 57 of the pulser ring 52 by attaching the pulse counting sensor 60 to the swing arm 35. The predetermined spacing δ can be made smaller by using the electromagnetic rotary sensor as the pulse counting sensor 60, thereby improving the detecting accuracy. Therefore, it is necessary to set the flatness of the pulser ring 52 within the permissible range. The flatness of the pulser ring 52 will be explained in detail by referring to Fig. 7. Fig. 4 is a sectional view taken along line 4-4 of Fig. 2. In this drawing, the swing arm 35 (an approximately triangular plate tapering toward the rear as viewed from side) is attached at the base portion by two upper and lower bolts 38, 38 to the swing unit 16; and at the lower slanting portion is formed a recess portion 35a, which is curved upward. In this recess portion 35a the caliper 41 is mounted. At the rear end the pulse counting sensor 60 is attached by bolts 65, 65. Furthermore, the pitch circle PD is drawn near the center of a predetermined distance from the outer edge 56 of the disc 55 of the pulser ring 52. On the pitch circle PD the pulse detecting holes 57 are made at a predetermined pitch P. The pulse detecting hole 57 is a slit (a narrow clearance). Fig. 5 is an exploded perspective view of the wheel speed detecting device (for the rear wheel) According to the embodiment of Fig. 2. In this drawing, the bolts 59 are inserted into the bolt holes 54a of the seat plate 54 of the pulser ring 52, to thereby attach the pulser ring 52 to the hub 18. Outside of the pulser ring 52 is mounted the brake disk 41. Then the bolts 45 are inserted into the bolt holes 41a of the brake disk 41, to attach the brake disc 41 to the hub 18. In this state, the body 62 of the pulse counting sensor 60 protrudes out of the hole 35b of the swing arm 35. Inside of the brake disc 41 is mounted the pulser ring 52. The pulse counting sensor 60 is placed in the vicinity of the side of the pulser ring 52. It is, therefore, possible to layout the wheel speed detecting device (for the rear wheel) 50 in compact design. Next, the method of fabricating the pulser ring of the wheel speed detecting device (for the rear wheel) described above will be explained. Figs. 6 (a) and (b) are drawings explaining the method of fabricating the pulser ring of the wheel speed detecting device (for the rear wheel) of the embodiment shown. In (a), a blank is pressed into a shaped body 58 unitarily including the cylindrical portion 53, seat plate 54, disc 54, and bent portion 55. The pulser ring can be enhanced in rigidity by forming the bent portion 56 (see Fig. 4 also) on the outer edge of the disc 55. Therefore, it is possible to decrease the plate thickness of the pulser ring. In (b), the shaped body 58 is pressed to form a plurality of pulse detecting holes 57 in the disc 55, and four bolt holes 54a (only two holes are shown) in the seat plate 54, thus completing the fabricating process of the pulser ring 52. Since the portion to be detected of the pulser ring 52 has been changed from a conventional tooth to the pulse detecting holes 57, the outer edge (i.e., the bent portion) of the pulser ring 52 can be left in a circular shape. Therefore, the disc 55 of the pulser ring 52 can be prevented from warping by the outer edge 56 if the pulse detecting holes 57 are made by pressing in the disc 55, thereby enabling to keep the flatness of the disc 55 within the permissible range. Figs. 7 (a) and (b) are a drawing explaining the pulser ring of the wheel speed detecting device (for the rear wheel) according to the embodiment of Fig. 2. (a) to (b) show. the embodiment of the pulser ring 52 shaped by pressing, and (c) to (d) show an example for comparison of the prior art pulser ring 153 (see Fig. 18) . (b) is a view seen from the arrow b in (a), and (d) is a view seen from the arrow d in (c). (a) shows the pulser ring 52 with a plurality of pulse detecting holes 57 formed by pressing along the outer edge 56. It is possible to connect the pulse detecting holes 57 at the forward end of the wall portions 57a by the outer edge 57, that is, to form the outer edge of the pulser ring 52 in a circular shape. (b) shows the outer edge of the pulser ring 52 having no warpage even after pressing the pulse detecting holes 57. Therefore, it is possible to keep the flatness of the pulser ring 52 within the permissible range. The distance δ between the pulse counting sensor 60 and the pulsar ring 52 can be set in a desired position. (c) shows the pulser ring 153 with a plurality of teeth 154 formed by pressing along the outer edge thereof. In this state, the plurality of teeth 154 protrude along the outer edge of the pulser ring 153. (d) shows the pulser ring 153 with the teeth 154 warped at the time of pressing the teeth 154. The flatness of the pulsar ring 153, therefore, can not be kept within the permissible range; and accordingly the clearance between the pulse counting sensor 156 and the pulser ring 153 increases to (δ+2×a), making it difficult to improve the detecting accuracy. It is, therefore, necessary set the flatness of the pulser ring 153 within the permissible range by correcting the warpage a of the teeth 154 after pressing the pulsar ring 153. Next, the wheel speed detecting device 80 for the front wheel will be explained. It should be noted that the same members as those in the wheel speed detecting device 50 for the rear wheel are designated by the same reference numerals and will not be described. Fig. 8 is a side view of the wheel speed detecting device for the front wheel according to a further embodiment that is not part of the present invention. In this drawing, a front axle 70 is attached by a nut 71 to the front fork 13; the front wheel 14 is rotatably attached to the front fork 13; a brake disc 73 of the hydraulic front disc brake 28 is attached by bolts 74 to the front wheel hub (not shown); a bracket 5 is attached by bolts 76, 76 to the front fork 13; and a brake caliper 77 is attached to the bracket 75, thus being located on the outer peripheral side of the brake disc 73. The wheel speed detecting device 80 for the front wheel, like the wheel speed detecting device 50 for the rear wheel, is comprised of the pulser ring 52 attached on the front wheel 14 side (an unillustrated front wheel hub), and the pulse counting sensor 60 attached on the vehicle body side (the bracket 75). The wheel speed detecting device 80 for the front wheel functions to detect the rotational speed (the wheel speed) of the front wheel 14 by counting the pulse detecting holes 57 in the pulser ring 52 by means of the pulse counting sensor 60. The pulser ring 52 is located inside of the brake disk 73, and in the vicinity of the side thereof is placed the pulse counting sensor 60. Therefore, it is possible to realize the compact layout of the wheel speed detecting device 80 for the front wheel. The pulse counting sensor 60 for the front wheel, like the pulse counting sensor 60 for the rear wheel, is an electromagnetic rotary sensor in which the body 62 is inserted into the mounting hole in the bracket 75 and then the overhanging plate 63 is attached by bolts 65, 65 to the bracket 75. Also like in the wheel speed detecting device 50 for the rear wheel, attaching the pulse counting sensor 60 to the bracket 75 makes it possible to position the detecting portion of the pulse counting sensor 60 for the front wheel oppositely to the pulse detecting holes 57 of the pulser ring 52. Next, further embodiments will be explained. The same members as those in the first embodiment are designated by the same reference numerals and will not be described. Fig. 9 is a sectional view of the wheel speed detecting device, according to a further embodiment that is not part of the present invention, mounted to the rear wheel. A wheel speed detecting device 90 for the rear wheel is comprised of a pulser ring 92 mounted on the wheel side and a pulse counting sensor 100 mounted on the vehicle body side. The pulser ring 92 includes a disc 93 with a sensing surface 93a directed toward the pulse counting sensor 100, pulse detecting holes 95 formed in the disc at predetermined pitches near the center of a predetermined distance from the outer edge 94 of the disc 93, a stiffening rib (inner rib) 96 formed along the vicinity of the inner periphery 93b of the disc 93, a seat plate 97 formed on the bottom of the inner rib 96, and a stiffening rib (outer rib) formed along the vicinity of the outer region 93c of the disc 93. The inner rib 96 is an annular portion formed by bending along the vicinity of the sensing surface 93a, that is, along the vicinity of the inner periphery 93b of the sensing surface 93a. The outer rib 98 is an annular portion formed by bending along the vicinity of the sensing surface 93a, that is, along the vicinity of the outer region 93c of the sensing surface 93a. The pulser ring 92, like the pulser ring 52 of the first embodiment, is provided with four bolt holes 97a (only two holes are shown) in the seat plate 97. Bolts 97b are inserted into these bolt holes 97a and tightened into the hub 99, thereby installing the pulser ring 92 to the hub 99. The hub 99 is properly positioned in a predetermined position in the direction of vehicle width in order to position the rear wheel 17 (shown in Fig. 2) in a predetermined position in the direction of the wheel width. Therefore, it is possible to place the pulser ring 92 in a desired position in the direction of vehicle width by mounting the pulser ring 92 on the hub 99. The pulse counting sensor 100, like the pulse counting sensor 60 of the first embodiment, is an electromagnetic rotary sensor attached on an unillustrated swing arm, and has a like function as the pulse counting sensor 60. According to the pulser:ring 92, the inner and outer ribs 96 and 98 are formed in the vicinity of the sensing surface 93a, that is, along the inner periphery 93b and the outer region 93c of the sensing surface 93a respectively, thereby enabling to improve the rigidity of the disc 93 having the sensing surface 93a. Therefore, the flatness of the sensing surface 93a can be kept within the permissible range even if the plate thickness t of the pulser ring 92 is set at a small value. It is, therefore, possible to keep a high-accuracy distance δ between the sensing surface 93a and the detecting surface 101 of the pulse counting sensor 100. Therefore, the weight of the pulser ring 92 can be reduced, thereby decreasing cost and enhancing vehicle performance. Furthermore, since the flatness of the pulser ring 92 is kept within the permissible range, the detection accuracy of the wheel speed detecting device 90 can be improved. Figs. 10 (a) and (b) are explanatory views of the rigidity of the wheel speed detecting device according to the shown embodiment. (a) shows a pulser ring 160 as an example for comparison and (b) shows the pulser ring 92 as an example, explaining the setting of the plate thickness t of the pulser ring 92 at one-sixth of the plate thickness t 1 of the pulser ring 160. In (a), setting a great plate thickness t 1 of the pulser ring 160 increases the rigidity of the purser ring 160 and also improves the accuracy of the predetermined clearance δ from the detecting surface 162 of the pulse counting sensor 162a to the sensing surface 160a of the pulser ring 160. Assuming that the plate thickness of the pulser ring 160 is t 1 and the width of the sensing surface 160a is h 1 , the modulus of section Z 1 is given by Z 1 = h 1 x (t 1 ) 2 /6 Here, presume t 1 = 6 mm and h 1 = h , and the following equation is given by Equation (1). Z 1 = h x (6) 2 /6 = 6h In (b), suppose that t is the plate thickness of the Pulser ring 92, h 2 is the width of the sensing surface 93a, t 2 is a distance from the sensing surface 93a to the end of the outer rib 98 (the length of the outer rib 98), t 3 is a distance from the inner surface of the disc 93 to the end of the outer rib 98, and h 3 is a distance from the inside surface of the inner rib 96 to the inside surface of the outer rib 98, the modulus of section Z 2 is given by the following equation. Z 2 = l 2 / (t 2 /2) Where l 2 is a geometrical moment of inertia, and is expressed by l 2 = {h 2 x (t 2 ) 3 /12 - h 3 x (t 3 ) 3 /12} Substituting Equation (4) in Equation (3) gives Z 2 = h 2 x (t 2 ) 2 /6 - h 3 x (t 3 ) 3 /(6 x t 2 ) Here, suppose that t = 1 mm,. t 2 = 10 mm, h 2 = h, t 3 = 9 mm, and h 3 = h - 2 × 1 , and from Equation (5) is obtained the following equation Z 2 = h x (10) 2 /6 - (h - 2) x (9) 3 /(6 x 10) Here, suppose that h = 16 mm, and the relationship Z 2 = Z 1 is obtainable from Equation (2) Z 1 = 6 x 16 = 96 and from Equation (6) Z 2 = 16 x (10) 2 /6 - (16 - 2) x (9) 3 /(6 x 10) = 95.8 It is understood from the above explanation that since the inner and outer ribs 96 and 98 are provided, the modulus of section Z 2 of the pulser ring 92 can be kept equal to the modulus of section Z 1 of the pulser ring 160 of (a) if the plate thickness t of the pulser ring 92 of (b) is reduced to one-sixth of the plate thickness t 1 of the pulser ring 160 of (a) . [0059] Therefore the pulser ring 92 of (b) , like the pulser ring 160 of (a), also can be set accurately at the predetermined distance δ from the detecting surface 101 of the pulse counting sensor 100 to the sensing surface 93a. The plate thickness t of the pulser ring 92 and the length of the inner and outer ribs 96 and 98 may be set to optional values. It is to be noticed that, in the shown embodiment, an example provided with the inner and outer ribs 96 and 98 adopted as stiffening ribs has been explained, and the same effect is obtained if either one of the inner and outer ribs 96 and 98 is adopted. Figs. 11 (a) and (b) are sectional views of the wheel speed detecting device, according to a further .embodiment that is not part of the present invention, mounted on the rear wheel. The wheel speed detecting device 102 for the rear wheel includes a pulser ring 103 mounted on the wheel side and the pulse counting sensor 100 mounted on the vehicle body side The pulser ring 103 is comprised of a disc 104 the sensing surface 104a of which is directed toward the pulse counting sensor 100, pulse detecting holes 106 formed at a predetermined pitch near the center of a predetermined distance from the outer edge 105 of the disc 104, a stiffening rib (inner rib) 107 formed along the vicinity of the inner periphery 104b of the disc 104, a seat plate 108 formed at the bottom of the inner rib 107, and a stiffening rib (outer rib) 109 formed along the vicinity of the outer periphery 104c of the disc 104. The inner rib 107 is an annular portion formed along the vicinity of the sensing surface 104a, that is, along the vicinity of the inner periphery 104b of the sensing surface 104a. The outer rib 109 is an annular portion formed along the vicinity of the sensing surface 104a, that is, along the vicinity of the outer periphery 104c of the sensing surface 104a. Reference numeral 108a denotes a bolt hole, which is a hole for bolting the pulser ring 103 to the hub. In the pulser ring 103, the inner and outer ribs 107 and 109 are formed in the vicinity of the sensing surface 104a, that is, along the inner periphery 104b and outer periphery 104c of the sensing surface 104a. Therefore, like the third embodiment, the disc 104 constituting the sensing surface 104a can be increased in rigidity. Therefore, if the plate thickness t of the pulser ring 103 is set small, the flatness of the sensing surface 104a can be kept within the permissible range; it is, therefore, possible to accurately keep the distance δ between the sensing surface 104a and the detecting surface 101 of the pulse counting sensor 100. Therefore, it is possible to reduce the weight of the pulser ring 103. Furthermore, since the flatness of the pulser ring 103 can be kept within the permissible range, the detecting accuracy of the wheel speed detecting device 102 can be enhanced. In the fourth embodiment, the provision of the inner and outer ribs 96 and 98 as the stiffening ribs has been explained. outer ribs 96 and 98 as the stiffening ribs has been explained. It should be noticed that the same effect can be obtained even when either one of the inner and outer ribs 96 and 98 is formed. Figs. 12 (a) and (b) are sectional views of the wheel speed detecting device, according to a further embodiment that is not part of. the present invention, mounted on the rear wheel. The wheel speed detecting device 110 for the rear wheel includes a pulser ring 112mounted on the wheel side and the pulse counting sensor 100 mounted on the vehicle body side. The pulser ring 112 comprises a disc 113 with its sensing surface 113a directed toward the pulse counting sensor 100, pulse detecting recesses 115 formed at a predetermined pitch near the center of a predetermined distance from the outer edge 114 of the disc 113, a stiffening rib 116 formed on the back side 113b (i.e., the back side of the sensing surface 113a) of the disc 113, and a seat plate 117 formed in the inside of the disc 113. The stiffening rib 116 is an annular body formed on the back side 113b of the sensing surface 113a. Reference numeral 117a denotes a bolt hole, through which the pulser ring 112 is attached by a bolt to the hub. In the pulser ring 112, since the stiffening rib 116 is formed on the back side 113b of the sensing surface 113a, it is possible to increase the rigidity of the disc 113 which constitutes the sensing surface 113a. Therefore, if the plate thickness t of the pulser ring 112 is set small, the flatness of the sensing surface 113a can be held within the permissible range, thus enabling to keep an accurate distance δ between the sensing surface 113a and the detecting surface 101 of the pulse counting sensor 100. It, therefore, is possible to decrease the weight of the pulser ring 112 and to lower cost. Furthermore, as the flatness of the pulser ring 112 can be held within the permissible range, the detecting accuracy of the wheel speed detecting device 110 can be enhanced Figs. 13 (a) and (b) are sectional views of the wheel speed detecting device of the present invention mounted on .the rear wheel. The wheel speed detecting device 120 for the rear wheel comprises a pulser ring 122 mounted on the wheel side and the pulse counting sensor 100 mounted on the vehicle body side. The pulser ring 122 comprises a disc 123 with its sensing surface 123a directed toward the pulse counting sensor 100, pulse detecting holes 125 opened at a predetermined pitch near the center of a predetermined distance from the outer edge 124 of the disc 123, a stiffening rib (the inner rib) 126 formed along the vicinity of the inner periphery 123b of the disc 123, a seat plate 127 formed on the bottom of the inner rib 126 and inside of the disc 123, and a stiffening rib (the outer rib) 128 formed along the vicinity of the outer periphery 123c of the disc 123. The inner rib 126 is an annular body formed along the inner periphery 123b of the sensing surface 123a, with its height L1 being set greater than the distance δ from the sensing surface 123a to the detecting surface 101 of the pulse counting sensor 100. The outer rib 128 is an annular body formed along the outer periphery 123c of the sensing surface 123a, with its height L1 being set greater than the distance δ from the sensing surface 123a to the detecting surface 101 of the pulse counting sensor 100. Therefore, the clearance between the sensing surface 123a and the pulse counting sensor 100 (i.e., a clearance corresponding to the distance δ) can be covered with the inner and outer ribs 126 and 128. Therefore, it is possible to keep the clearance between the sensing surface 123a and the pulse counting sensor 100 by the inner and outer ribs 126 and 128, thereby preventing entry of a flying substance such as a flying rock into the clearance. Reference numeral 127a denotes a bolt hole, which is used to bolt the pulser ring 122 to the hub. According to the embodiment of the present invention, the pulser ring 122 is provided with inner and outer ribs 126 and 128 formed in the vicinity of the sensing surface 123a, that is, along the inner periphery 123b and outer periphery 123c of the sensing surface 123a, whereby the disc 123 having the sensing surface 123a can be enhanced in rigidity. Therefore, if the plate thickness t of the pulser ring 122 is set small, the flatness of the sensing surface 123a can be held within the permissible range. It is, therefore, possible to accurately keep the distance δ between the sensing surface 123a and the detecting surface 101 of the pulse counting sensor 100, and accordingly to decrease the weight of the pulser ring 122 and lower the cost. Furthermore, since the flatness of the pulser ring 122 can be kept within the permissible range, the detecting accuracy of the wheel speed detecting device 120 can be improved. Furthermore, according to the embodiment of the present invention, the inner and outer ribs 126 and 128 are provided along the sensing surface 123a, and the height L1 of the inner and outer ribs 126 and 128 is set greater than the distance δ from the sensing surface 123a to the pulse counting sensor 100. Therefore, the clearance (i.e., the clearance corresponding to the distance δ) between the sensing surface 123a and the pulse counting sensor 100 can be covered with the inner and outer ribs 126 and 128. That is, the inner and outer ribs 126 and 128 are usable as protective covers. Therefore, since the clearance between the sensing surface 123a and the pulse counting sensor 100 is covered by the inner and outer ribs 126 and 128, a flying substance like a flying rock can be prevented from entering the clearance. As a result, the detecting accuracy of the wheel speed detecting device 120 can be further improved. Furthermore, because the inner and outer ribs 126 and 128 are able to serve also as protective covers, it is unnecessary to provide a separate protective cover, thereby enabling to prevent an increase in the component count, and furthermore to dispense with installation of a protective cover, and consequently to lower the cost. According to the embodiment of the present invention, the inner and outer ribs 126 and 128 as the stiffening ribs have been explained. A similar effect is obtainable also when only either of the inner ribs 126 or outer ribs 128 is provided. Fig. 14 is a sectional view of the wheel speed detecting device, according to a further embodiment that is not part of the present invention, mounted on the rear wheel. In the wheel speed detecting device 130 for the rear wheel, the pulse detecting holes 135 made in the pulser ring 132 are counted by means of the pulse counting sensor 100, to thereby detect the rotational speed (the wheel speed) of the rear wheel 17 (shown in Fig. 2). The pulser ring 132 is comprised of a disc 133 mounted by a bolt 138 to the hub 137, and a pulse detecting hole 135 formed at a predetermined pitch on a pitch circle drawn near the center of a predetermined distance from the outer edge 134 of the disc 133. The pulser ring 132 is produced of a pressed part with the pulse detecting hole 135 punched by a punch 139 (shown in Fig. 16). of both sides of the pulser ring 132, the side directed to the punch 139 is the first surface 132a, and the other side is the second surface 132b. The pulser ring 132 is attached to the hub 137 in with the second surface 132b directed toward the pulse counting sensor 100. The hub 137 is properly positioned in a predetermined position in the direction of vehicle width for the purpose of positioning the rear wheel in the predetermined position in the direction of the wheel width. Therefore, it is possible to mount the pulser ring 132 in a desired position on the hub 137 in the direction of vehicle width The pulse counting sensor 100 is an electromagnetic rotary sensor of such a configuration that the body 100a is inserted in a mounting hole 140a of a swing arm 140; and the mounting overhanging plate 100b extended unitarily from the body 100a is pressed against the swing arm 140; the overhanging plate 100b being attached by a bolt 141 to the swing arm 140b. The detecting surface 101 of the detecting portion 100c is directed toward the second surface 132b of the pulser ring 132 by attaching the pulse counting sensor 100 to the swing arm 140, and the clearance between the detecting surface 101 and the second surface 132b is set to the predetermined clearance δ. Fig. 15 is a sectional view taken along line 15-15 of Fig.14, in which, when the side facing to the punch 139 is called the first surface 132a, and the other side is called the second surface 132b, the pulser ring 132 is attached with the second surface 132b directed to the pulse counting sensor 100. The pulse detecting hole 135 formed by punching with the punch 139 is provided with a sharp square edge 136a on the second surface 132b side (i.e., a part where a hole wall surface 135a of the pulse detecting hole 135 and the sensing surface 133a mutually intersect). Therefore, it is possible to clearly distinguish the sensing surface 133a from the pulse detecting hole 135. Therefore, the sensing performance of the pulse counting sensor 100 can be improved and accordingly the detecting accuracy of the wheel speed detecting device 130 can be enhanced. Figs. 16 (a) and (b) are explanatory views of a fabricating process for fabricating the wheel speed detecting device according to this invention. In (a), the punch 139 is set on the first surface 132a of the blank 145 and fed down into the first surface 132a. As the punch 139 is driven downward into the first surface 132a, the first surface 132a is depressed. At this time, the first surface 132a is slightly depressed at an area within the range H along the outer surface of the punch 139, and there takes place a so-called "droop" 136b along the outer surface of the punch 139. In (b), the pulser ring 132 is obtained by punching the pulse detecting hole 135 in the blank 145 by the use of the punch 139. In punching the pulses ring 132, the. droop 136a occurs along the outer periphery of the pulse detecting hole 135 being made in the first surface 132a. In the meantime, there takes place no droop along the outer periphery of the pulse detecting hole 135 being made in the second surface 132b where the punch 139 cuts through, whereby, therefore, a sharp square cut detecting hole edge 136a is formed on the pulse detecting hole 135. Figs. 17 (a) and (b) are explanatory views of operation of the wheel speed detecting device according to this invention In (a), the pulse detecting hole 172 is detected by the pulse counting sensor 175 with the Pulser ring 170 turned in the direction of the arrow. In this case, since the droop 172a of the pulse detecting hole 172 is exposed to the pulse counting sensor 175, the pulse counting sensor 175 detects the depression of the droop 172a. Therefore, the magnetic variation of the pulse counting sensor 100 becomes indefinite, resulting in a failure in accurate detection of the pulse detecting hole 172. In (b), the pulse detecting hole 135 is detected by the pulse counting sensor 100 with the pulser ring 132 turned in the direction of the arrow. The droop 136b of the pulse detecting hole 135 is positioned on the opposite side of the pulse counting sensor 100, and the detecting hole edge 136a faces to the pulse counting sensor 100. The detecting hole edge 136a is formed sharp and square in section, so that the pulse detecting hole 135 is clearly distinguishable from the sensing surface 133a, and accordingly can be accurately detected. Therefore, the magnetic variation of the pulse counting sensor 100 is made clear, enhancing the sensing performance by the pulse counting sensor 100 and accordingly improve the detecting accuracy of the wheel speed detecting device 130. In the present embodiment is explained an example of the wheel speed detecting device applied to a motorcycle. It should be noticed, however, that the wheel speed detecting device is applicable to other types of motor vehicles. In the example described above, it is to be noted that the pulse detecting hole of the pulser ring is a slit and may be a round hole, and furthermore a recess such as a hole may be adopted in place of the pulse detecting hole. Furthermore, heretofore explained is the adoption of the electromagnetic rotary sensor as the pulse counting sensor In this case also, other types of sensors, such as a photo sensor, may be used. It should be noticed that in the embodiment the wheel speed detecting device of the present invention applied to the rear wheel of a motorcycle has been explained, and the same effect is obtainable also when the wheel speed detecting device is applied to the front wheel of a motorcycle. Explanation of Reference Numerals 10 ... motorcycle; 14 ... wheel side (front wheel); 17 wheel side (rear wheel); 18, 19, 137 ... hub; 35 ... body side (swing arm); 50, 90, 102, 110, 120, 130 ... wheel speed detecting device (for the rear wheel); 52, 92, 103, 112, 122, 132 ... pulsar ring; 55, 93, 103, 113, 123, 133 ... disc; 56 ... outer edge (bent portion); 57, 95, 106, 125, 135 ... pulse detecting hole; 60, 100 ... pulse counting sensor; 75 ... wheel body side (bracket); 80 ... wheel speed detecting device (for the front wheel); 93a, 104a, 113a, 123a, 133a ... sensing surface; 94, 105, 115, 124, 134 ... outer edge; 96, 107, 126 ... stiffening rib (inner rib); 98, 109, 128 ... stiffening rib (outer rib); 115 ... pulse detecting recess; 116 ... stiffening rib; 132a .... first surface; 132b .. second surface; 139 ... punch; 140 ... swing arm; PD ... pitch circle; L1 ... rib height; P . . . pitch; δ ... predetermined clearance from pulsar ring to pulse counting sensor In summary, it is an object to provide an art capable of enhancing the detection accuracy of a wheel speed detecting device and reducing cost. The wheel speed detecting device according to an embodiment for the rear wheel comprises the pulser ring mounted on the rear wheel hub, and a pulse counting sensor mounted on the swing arm. The pulser ring comprises the disc, and the pulse detecting holes formed at a predetermined pitch on a pitch circle drawn at a radially inward circumferential position spaced at a predetermined distance from the outer edge of the disc. The pulse detecting hole is formed in a position on the center side apart from the outer edge of the pulser ring, leaving the outer edge of the pulser. ring in a circular form. It is, therefore, possible to prevent warpage of the pulser ring by the outer edge portion if the pulse detecting holes are made by pressing.

Claims: A wheel speed detecting device comprising a pulser ring (52, 92, 103, 112, 122, 132) mounted on a wheel (14, 17) and a pulse counting sensor (60, 100) to be mounted on the side of the motorcycle body (13, 35), wherein the putser ring (52, 92, 103, 112, 122, 132) comprises a pulser disc (55, 93,103,113,123,133) with pulse detecting holes (57, 95, 106, 125, 135) or pulse detecting recesses formed therein at predetermined certain pitches (P) on a pitch circle (PD) drawn in a radially inward circumferential position spaced at a predetermined distance from an outer edge (56, 94, 105, 115, 124, 134) of the pulser disc (55, 93, 103, 113, 123, 133), said pulser disc (123) has a sensing surface (123a) directed towards said pulse counting sensor (100), characterized in that a stiffening rib (126, 128) is provided projecting from said sensing surface (123a) toward said pulse counting sensor (100), wherein the height (L1) of said stiffening rib is set larger than a clearance (δ) between said sensing surface (123a) and said pulse counting sensor (100), said stiffening rib (126, 128) being adapted to radially cover a detecting surface (101) of said pulse counting sensor (100). A wheel speed detecting device according to claim 1, characterized in that two stiffening ribs are provided projecting from said sensing surface (123a), wherein one of said stiffening ribs (126) is provided radially inward of said pulse counting sensor (100) and wherein the respective other stiffening rib (128) is provided radially outward of said pulse counting sensor (100), the height (L1 ) of said stiffening ribs (126, 128) being set larger than said clearance (δ) from said sensing surface (123a) to said pulse counting sensor (100), wherein both stiffening ribs (126. 128) are adapted to radially cover said detecting surface (101) of said pulse counting sensor (100). A wheel speed detecting device according to any of the preceding claims, characterized in that said pulser ring (52, 92, 103, 112, 122, 132) is fixed to said wheel (14, 17) by bolts penetrating bolt holes (54a, 97a, 108a, 117a, 127a) formed on a seat plate (54, 97, 108, 117, 127) extending radially inward of said sensing surface (93a, 104a, 113a, 123a, 133a). A wheel speed detecting device according to any of the preceding claims, characterized in that said pulser ring (52, 92, 103, 112, 122, 132) is mounted to an outer side surface of said wheel (14, 17), which surface faces substantially in an axial direction of said wheel (14, 17).

Inventors: IGARASHI MAKOTO, WAKABAYASHI TAKESHI, IGARASHI, MAKOTO, WAKABAYASHI, TAKESHI
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 2000
Main classification: B62J39
IPC codes: B60T1, B60T8, G01P1, G01P3, B62L1, B62J99