Inhibitor switch

The present invention relates to an inhibitor switch for switching contacts in accordance with the positions due to transmitting operation of an automatic transmission device used for automobiles, and particularly to an improvement of an inhibitor switch in which the contact portion is composed of a magnetic sensor and a permanent magnet.

Hitherto, there has been known the technique as described in, for example, Japanese Utility Model Publication Laid-open 59-146222 as a prior art of this type. The prior art has such construction that a permanent magnet is fitted in a lever by using adhesive, and a printed substrate provided with a magnetic flux detecting element is molded in a main body through an injection molding method. It has been required for an inhibitor switch to provide sufficient precision for the contact sections thereof. In the conventional inhibitor switches, cutting works have been provided for obtaining a precise dimension of the permanent magnet.

The conventional inhibitor switch as mentioned above has the problem that since the precision in dimension of the permanent magnet is obtained by the cutting works, manufacturing cost thereof becomes extremely high.

The object of the present invention is to present an inhibitor switch with a low manufacturing cost.

The inhibitor switch as claimed in Claim 1 has the structural feature that in an inhibitor switch comprising a movable base provided with permanent magnet and adapted to be rotated in accordance with the transmission operating position of an automatic transmission device, a pole base provided with magnetic sensors for detecting the magnetic flux from the permanent magnets, and a cover body for rotatably supporting the movable base in corporation with the pole base, the inhibitor switch is characterized in that the movable base is inserted with a yoke for mounting the permanent magnet by using an injection molding method. Therefore, it becomes possible to integrally form the permanent magnets for generating magnetic flux to be sensed by the magnetic sensor on the movable base with high precision thereby increasing the precision of the inhibitor switch.

The inhibitor switch according to Claim 1 as claimed in Claim 2, has the structural feature that the yoke is provided with folded sections each one end of which is exposed on the upper surface of the movable base, and bottom pieces on which the permanent magnets are mounted respectively. Therefore, it becomes possible to obtain a precise formation of the permanent magnet by a die-casting method.

The inhibitor switch according to Claim 2 as claimed in Claim 3, has the structural feature wherein the yoke is composed such that each of the bottom pieces is formed in an arc shape with the center of a cylindrical shaft section which is the same center as that of the movable base and sequentially disposed, and each of the folded sections is provided on each end of the bottom pieces. Therefore, it becomes possible to improve the manufacturing property upon the die-casting of the permanent magnet because the yoke serves as a die-cast per se for forming the permanent magnet.

The inhibitor switch according to Claim 1, 2, or 3 as Claimed in Claim 4, has the structural feature that the movable base is integrally formed with a cylindrical shaft section and a movable arm mounted with the yoke, and further integrally formed with projection sections to be slidably contacted to sliding surfaces of the pole base respectively at the inner and outer peripheries of the cylindrical shaft section respectively. Therefore, it becomes possible to reduce the friction due to the movable base and to improve the smoothness thereof.

The inhibitor switch according to Claim 2, 3, or 4 as claimed in Claim5, has the structural feature that each of the permanent magnets is composed of a magnetic body mounted within the hollowed portion formed with bottom pieces and the folded sections of the yoke by using an injection molding method. Therefore, it becomes possible to reduce the cost for die-casting and the manufacture cost.

The inhibitor switch according to Claim 5 as claimed in Claim 6, has the structural feature that the yoke is provided with gate holes for injecting the magnetic body to form the permanent magnets on the bottom pieces. Therefore, it becomes possible to avoid the drop out of the permanent magnet from the movable base.

The inhibitor switch according to Claim 4, 5 or 6 as claimed in Claim 7, has the structural feature that the pole base is integrally formed with the bottom surface through the injection molding method, and provided with conductive bodies inserted into the pole base through the injection molding method and electrically connected to a substrate mounted with the magnetic sensors, the shaft hole provided at the end portion of the bottom surface for coupling with the cylindrical shaft section, the sliding surfaces formed at the periphery of the shaft hole for allowing the sliding motion of the projected section, and the sliding surface formed at the periphery of the bottom surface for allowing the sliding motion of the projected sections. Therefore, it becomes possible to usually maintain a constant gap between the permanent magnets and the magnetic sensors thereby increasing the sliding property thereof. Moreover, since the movable base does not contact with the substrate, any undesirable influence for the magnetic sensors and electronic elements is avoided.

The embodiments of the present invention will be described with reference to the attached drawings 1 to 8 hereinafter, in which

• Fig. 1 is an exploded sectional view of the embodiment of the present invention;
• Fig. 2 is a central enlarged sectional view of the embodiment of the resent invention;
• Fig. 3 is an enlarged bottom view showing the movable base of the embodiment of the present invention;
• Fig. 4
  
  

  is an enlarged sectional view taken along the line x-x in Fig. 3;

• Fig. 5 is a perspective view showing the yoke of the embodiment of the present invention;
• Fig. 6 is a plan view showing the pole base of the embodiment of the present invention;
• Fig. 7 is an enlarged sectional view taken along the line Y-Y in Fig. 5;
• Fig. 8 is an enlarged sectional view showing the substrate of the embodiment of the present invention;

Numeral 1 denotes a movable base integrally formed with a cylindrical shaft section 1a of an automatic transmission device into which a transmission lever shaft (not shown) is inserted, and a movable arm 1b having permanent magnets 4 and a yoke 5. As shown in Fig. 2, the movable base 1 is rotatably supported by a cover body 2 and a pole base 3 in such a manner that the upper cylinder shaft section 1c of the cylindrical shaft section 1a is fitted with the shaft hole 2a of the case body 2, and further the lower cylinder shaft section 1d of the cylindrical shaft section 1a is fitted with the shaft hole 3a of the pole base 3. The cylindrical shaft section 1a may be one directly coupled with the transmission lever shaft, and further may be one indirectly coupled with the shaft (not shown) interlocking with the transmission lever shaft.

As shown in Figs. 3, 4 and 5, the yoke 5 is formed such that four arc-shaped iron plates are connected with each other integrally, each of the iron plates being formed as an approximate U-letter shape, and further are formed with gate holes 5a at the approximately center portion of each of four bottom surfaces respectively. Moreover, the permanent magnet 4 would not be limited in terms of its kind, material and the like.

In an example for manufacturing of the movable base 1, pins (not shown) are at first inserted into the gate holes 5a respectively, and then the yokes 5 are molded with resin by using an injection molding method. In the yokes 5 of the movable base 1 as a primary molded product made by using the injection molding method, the portion at which the bottom pieces 5b and folded sections 5c are exposed is made as a hollowed portion. Then, this primary molded product is set on a metal mold used for forming the permanent magnet. Then, the mixture of neodymium powder (magnetic material) and PPS pellets which are called as bonded magnet or a plastic magnet is injected onto the bottom piece 5b of the hollowed portion of the yoke 5 thereby forming the permanent magnet 4 as a secondary molded product. Thus, the manufacture of the movable base 1 is finished.

Moreover, as shown in, for example Figs. 3, 4 and 5, since each of the gate hole 5a is provided at the approximately center portion of each permanent magnet 4, each permanent magnet 4 is effectively avoided to be dropped out. The number of the gate holes 5a is not specified. In the case where, for example, a single gate hole 5a is mounted on the bottom piece 5b, it is set at an approximately center portion of the bottom piece 5b. Furthermore, as shown in Fig. 4, the movable base 1, the yoke 5, and the permanent magnet 4 are aligned on a single surface upon which the permanent magnets 4 of the movable base 1 are exposed.

As shown in Fig. 1 and 2, the cylindrical shaft section 1a is formed with a key 1e to be fitted to the key slit of the transmission lever shaft at the inner wall of the cylindrical shaft section 1a, and formed with grooves 1h and 1i for receiving O-rings 11 and 12 at the periphery of the cylindrical shaft section 1a respectively. The hermetic property between the cover body 2 and the cylindrical shaft section 1a is increased by the O-ring 11 fitted into the groove 1h, and the hermetic property between the pole base 3 and the cylindrical shaft section 1a is increased by the O-ring 12 fitted into the groove 1i.

As shown in Fig. 3, at the upper surface of the movable arm 1b, four arc-shaped permanent magnet 4 and the folded section 5c of the yoke 5 are disposed at the both ends of the permanent magnet 4. Moreover, at the lower side surface of the movable arm 1b, projected sections 1f and 1g formed integrally with the movable arm 1b are projected at the periphery of the lower side shaft section 1d and the outer periphery of the movable arm 1b respectively. Each end of the projected sections 1f and 1g is formed with a semi-circle-shaped section, thereby enabling a slidable operation on the periphery of the shaft hole 3a of the pole base 3 and further the sliding surfaces 3e and 3f of the outer periphery of the bottom surface 3d of the pole base 3 respectively.

As shown in Figs. 1 and 2, the cover body 2 has a shaft hole 2a to be fitted to the upper side shaft section 1c and a ring-shaped projection 2b to be fitted to a coupling groove 3b formed on the peripheral lower surface of the pole base 3. The cover body 2 and the pole base 3 are made of the resin material having oilproof property and heat resistance property, and an ultrasonic welding can be easily applied to such resin material. Such resin material may be nylon resins, polypropylene or the like. The cover body 2 may be fitted to the pole base 3 through the movable base 1 and the substrate 6, and then the coupled portion between the coupled groove 3b and the ring-shaped projection 2b is welded to achieve a hermetic seal by using an ultrasonic welding or a vibration welding.

The pole base 3 is formed so that a conductive body 7 and metallic rings 8 are inserted therein, and may be fixed by using screws passing through the metallic rings 8 respectively at the outer side of the automatic transmission device. As shown in Fig. 6, one of the connecting sections 7a of the conductive body 7 integrally formed with the pole base 3 is projected from the bottom surface 3d, and the other of the conductive body 7 is projected into a connector section 3c as terminals 7b. The pole base 3 provides a slide surface 3e on which the projected section 1f mounted at the lower surface of the movable base 1 can slide, at the outer periphery of the shaft hole 3a. Moreover, the pole base 3 provides a slide surface 3f on which the projected section 1g mounted at the lower surface of the movable base 1 can slide, at the outer periphery of the bottom surface 3d.

As shown in Figs. 1, 2 and 6, the slide surfaces 3e and 3f are made smoothly in order to increase the sliding property between the movable base 1 and the projected sections 1f and 1g. The pole base 3 has a shaft hole 3a at the inner side of the slide surface 3e, and outer periphery 3g at the outer side of the slide surface 3e adjacent thereto, so as to guide the projected section 1f. Moreover, the pole base 3 has an inner side periphery 3h at the side of the shaft hole 3a of the slide surface 3f and an inner wall 3p at the outside of the slide surface 3f, so as to guide the projected section 1g sliding adjacent thereto.

The slide surfaces 3e and 3f are provided with the inner and outer periphery edges 3g and 3h each end of which is rounded so as to guide the movable base 1. The pole base 3 is formed with a groove 3k to be inserted with a packing 13 for sealing the contact surface which is located at the periphery of the bottom surface 3d between the cover body 2 and the pole base 3. Moreover, numeral 3n in Fig. 6 denotes a hole for positioning the shaft of the transmission lever of the automatic transmission device.

The yoke 5 is a molding frame for forming the desired shape of the permanent magnet 4 which is formed with magnetic material by using the injection molding method. The yoke 5 has the bottom pieces 5b composing the bottom of the hollowed portion when the permanent magnet 4 is inserted into the movable base 1 as being the primary molded product during the injection molding operation. Moreover, the yoke 5 has the folded section 5c exposed to the upper surface of the movable base 1, the bottom pieces 5b forming the hollowed portion for receiving the permanent magnets 4 respectively, gate holes 5a, and interlocking sections 5d for interlocking the bottom pieces 5b and the other bottom pieces 5b. As shown in Figs. 3 and 5, the yoke 5 is composed of plural bottom pieces 5b interlocked with the interlocking sections 5d, and the folded section 5c for forming the hollowed portion at the end portion of each of the bottom pieces 5b upon the primary production of the movable base 1. Each of the bottom pieces 5b is made an arc-shaped piece having the center point P of the cylindrical shaft section 1a of the movable base 1.

As shown in Figs. 6 and 7, the substrate 6 is mounted in such a manner that the connecting sections 7a of the conductive body 7 projected from the bottom surface 3d of the pole base 3 are inserted into the through holes 6b respectively and welded by using solder. Moreover as shown in Figs. 6 and 8, two projections 3m projected from the bottom surface 3d of the pole base 3 are inserted into the positioning hole 6c and the position adjusting hole 6d respectively thereby positioning the substrate 6 at the predetermined position within the pole base 3, and then screws are used for fixing the substrate 6 by being inserted into the through holes 6a and screwed into the blind holes 3i.

As shown in Fig. 8, the positioning hole 6c is a circle mounted at the standard position for the substrate 6. The position adjusting hole 6d is an elongated hole for enabling a fine adjustment of the position for the substrate 6. The substrate 6 is mounted with electronic elements 10 and a plurality of the magnetic sensors 9 responding to the magnetic flux due to the permanent magnets 4 disposed in opposite to the magnetic sensors 9. The magnetic sensors 9 may be a Hall-effect device, a Hall IC, MR element or the like for detecting the magnetic flux. The magnetic sensors 9 are disposed so that the magnetic sensor does not contact with the movable base 1 as shown in Fig. 2. The gap H between the magnetic sensor 9 and the permanent magnet 4 may be about 0.1 mm to 0.6 mm.

The operation of the embodiment of the present invention constructed as mentioned above will be described in detail hereinafter.

When a driver operates the shift lever, the transmission operating position of the automatic transmission device for automobiles is changed. At that time, the movable base 1 received within the inhibitor switch is rotated around the cylindrical shaft section 1a in accordance with the movement of the shift lever, and the permanent magnets 4 are also moved in accordance with it. The magnetic sensor 9 of the substrate 6 mounted at the position adjacent to the movable base 1 detects the transmission operating position in response to the change of the magnetic flux due to the movement of the permanent magnet 4.