Parts unit with improved sealing performance and maintainability

Abstract: A rod body (21) having a reed switch (29) constituting a sensor, provided on a tip end thereof is inserted into a cylindrical sensor cover having its tip end closed. An O ring (23) attached to a sidewall of the rod body seals the inside of the sensor cover from the outside when the rod body is inserted in the sensor cover. The sensor cover is attached to a sensor support (3) to be fixed to component parts of a bicycle.

Description: The present invention relates to a unit for use on a two-wheeled vehicles as given in the preamble of claim 1 and, more particularly, to a sensor unit for storing therein a sensor for detecting revolving speed of wheels of bicycles or the like. Recently, speedometers are sometimes attached to bicycles in order to readily know travel speed, travel distance and the like of the bicycles. Fig. 5 is a side view of a conventional bicycle to which a speedometer is attached; and Fig. 6 is an enlarged view of a portion denoted with a symbol "X" of Fig. 5. Referring to Figs. 5 and 6, a speedometer 30 is mounted on a stem 31 of a handle of a bicycle 24. A magnet 26 is attached to a spoke 32 of a front wheel of the bicycle. A sensor 28 for generating one pulse signal each time magnet 26 passes in front of sensor 28 is mounted on a portion of a fork 34 corresponding to magnet 26. The signal generated by sensor 28 is input through a cord 11 to speedometer 30. Then, various types of operations are carried out in response to the input signal in speedometer 30. Information as to the calculated speed, travel distance and the like is supplied to a user. Fig. 7 is an enlarged view of sensor 28 of Fig. 6; Fig. 8 is a side view of sensor 28 taken along the line VIII-VIII of Fig. 7; and Fig. 9 is a section view of sensor 28 taken along the line IX-IX of Fig. 7. A description will now be made on the structure of a conventional sensor unit with reference to those figures. Sensor unit 28 comprises a sensor storage 39 for storing therein a reed switch 29 constituting the sensor, a sensor cover 35 for covering sensor storage 39, a band 5 for fixing sensor 28 onto fork 34, and a screw 7 for mounting sensor cover 35 pivotally on band 5. In sensor storage 39, reed switch 29 is soldered onto a base plate 25, and core wires of a cord 27 externally connected in sensor storage 39 are each soldered onto base plate 25. Sensor storage 39 and sensor cover 35 are combined together in concave and convex forms as shown in the figure. In order to protect reed switch 29 or the like against rainwater or the like introduced from the outside, reed switch 29, base plate 25, cord 27, the core wires thereof and the like are resin-sealed by polyurethane 41. In such a manner, the inside of the sensor is protected against water drops or the like introduced between sensor storage 39 and sensor cover 35. In the above-described conventional sensor unit, since it is necessary to seal the sensor with such resin as polyurethane or the like, it takes time to manufacture the sensor unit. Further, once the sensor is sealed with resin, any defects of reed switch 29, base plate 25 and the like cannot easily be inspected or repaired, resulting in a decrease in yield. From GB-A-2 059 595 a unit is known according to the preamble of claim 1. A transducer is mounted by means of clips to one of the forks. The transducer comprises a reed switch. The unit is made for measuring e.g. the speed of the wheeled vehicle. However, the specification is quiet on how to seal the unit and how to make inspection and repair possible. From EP-A-0 151 391 a data display unit for a bicycle is known. The data display is supplied with signals coming from a revolution detecting sensor employing a magnet fixed in a rotating wheel fork and a lead switch fixed in a wheel supporting member. From DE-A-32 26 557 means for measuring the distance covered by a bicycle is known. The means comprises a permanent magnet in the wheel and a module at the fork of the bicycle. The module com-prises a battery casing and a reed switch. Therefore, it is an object of the present invention to provide a unit for protecting parts for use in a two-wheeled vehicle, where-in inspection and repair are facilitated despite improved sealing. This object is solved by a unit with the features of claim 1. Preferred embodiments are given in the subclaims. In the unit thus structured, since the holding means inserted into the storage means is sealed from the outside, parts for a two-wheeled vehicle are securely protected from the outside and can easily be inspected and repaired. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. Fig. 1 is a side view showing the structure of a sensor unit according to one embodiment of the present invention. Fig. 2 is an overview of the sensor unit viewed from the line II-II of Fig. 1. Fig. 3 is an overview of the sensor unit viewed from the line III-III of Fig. 1. Fig. 4 is a section view taken along the line IV-IV of Fig. 1 and showing an internal structure of the sensor unit. Fig. 5 is a side view of a common bicycle provided with a speedometer and a sensor. Fig. 6 is an enlarged view of a portion "X" of Fig. 5. Fig. 7 is an enlarged view of the sensor unit of Fig. 6 and showing the structure of a conventional sensor unit. Fig. 8 is a view showing the structure of the sensor unit viewed from the line VIII-VIII of Fig. 7. Fig. 9 is a section view taken along the line IX-IX of Fig. 7. Fig. 1 is a side view showing the structure of a unit according to one embodiment of the present invention; Fig. 2 is a view viewed from the line II-II of Fig. 1; and Fig. 3 is a view viewed from the line III-III of Fig. 1. The structure of a sensor unit will now be described with reference to Figs. 1, 2 and 3. The sensor unit comprises: a cylindrical sensor housing 1 having its tip end closed for storing a sensor such as a reed switch or the like therein; a sensor support 3 having a portion of an open circular cross-section for accepting sensor housing 1 inserted, with a protrusion 13 provided on sensor housing 1 used as a reference; a band 5 having a portion of an open circular sectional form for fixing the sensor unit onto a fork 34; a screw 7 for pivotally connecting an open end of band 5 and sensor support 3 with each other; an opening 9 engaged with a protrusion 19 provided on sensor housing 1 for preventing the falling off of sensor housing 1, with sensor housing 1 inserted into sensor support 3; and a cord support 15 for connecting sensor housing 1 and a cord 11. Sensor support 3 has a neck 17 as shown in the figure 3. Relationship between neck 17 and band 5 is made pivotal by forming, e.g., a chrysanthemum-shaped unevennesses on both an end of neck 17 and that of band 5. Fastening screw 7 causes engagement of the unevennesses and enables its pivotal position to be fixed. Fig. 4 is a sectional view taken along the line IV-IV of Fig. 1 and showing in detail an internal structure of the sensor. Referring to Fig. 4, the sensor unit is attached to a rod-like sensor receiver 21 connected with cord support 15 supporting cord 11. The core wire of a cord 27 that runs through sensor receiver 21 and is taken out to its tip end is connected by soldering to a base plate 25. A reed switch 29 for generating one pulse signal each time a magnet passes in front of reed switch 29 is soldered onto base plate 25. Sensor receiver 21 is allowed to be freely inserted into cylindrical sensor housing 1 with its tip end closed. An O ring 23 is formed on a sidewall of sensor receiver 21. O ring 23 seals from the outside reed switch 29 or the like in sensor housing 1 having sensor receiver 21 inserted therein. Two protrusions 19 having such cross-section as shown in the figure are formed at opposing positions on sidewalls of sensor housing 1. Protrusions 19 are engaged with openings 9 formed on sidewalls of sensor support 3. When the sensor unit is taken out of sensor support 3, since a portion of sensor support 3 corresponding to protrusion 13 formed in sensor housing 1 is an open end, broadening the corresponding open portion makes it possible to release the engagement between protrusions 19 and openings 9 and to detach the sensor unit from the sensor support. While the sensor unit of the present invention is applied to the sensor unit of a speedometer in the foregoing embodiment, the present sensor unit is also applicable to other bicycle parts, the inside of which is necessary to be sealed from the outside. While a single O ring is employed in the foregoing embodiment, two or more O rings may be employed to further enhance sealing effects. Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the scope of the present invention being limited only by the terms of the appended claims.

Claims: A unit for use on a two-wheeled vehicle, comprising: storage means (1) having a cylindrical shape with one end closed and a sensor (29) inside said storage means (1); characterized in that holding means (21) having a rod-like shape holds said sensor (29) adjacent a tip end of said holding means (21); the other end of said storage means (1) is open for allowing said holding means (21) to be freely inserted therein with the sensor (29) from said other end; sealing means (23) seals the inside of said storage means (1) from the outside when said holding means (21) is inserted into said storage means (1); and the holding means (21) is removably held within the storage means (1). The unit according to claim 1, wherein said sealing means (23) comprises at least an O ring provided in said holding means (21). The unit according to claim 1 or 2, wherein said sensor (29) comprises a reed switch for detecting the revolving speed of the wheels of said vehicle. The unit according to one of claims 1 to 3, wherein: said holding means (21) is formed as a rod body; a cord (11) is connected through said rod body to said sensor (29); and said sealing means (23) is attached to a sidewall of said rod body. The unit according to one of claims 1 to 4, wherein a sensor support (3) having a cylindrical shape of cross-section is attached to a bicycle part, said storage means (1) being engaged with and freely inserted into said sensor support (3).

Inventors: TAKEDA GORO, TAKEDA, GORO
Applicants: CATEYE CO LTD, CATEYE CO., LTD.
Application year: 1992
Main classification: B62J39
IPC codes: G01C22, G01P3, B62J99