GB2346743A

GB2346743A - Rotary connectors

Info

Publication number: GB2346743A
Application number: GB0002368A
Authority: GB
Inventors: Nobuo Matsuzaki; Shunji Araki
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1999-02-05
Filing date: 2000-02-02
Publication date: 2000-08-16
Anticipated expiration: 2020-02-02
Also published as: JP3519008B2; JP2000228264A; GB0002368D0; GB2346743B

Abstract

A rotary connector has a pair of housings 10, 30 which are concentrically disposed and rotatably coupled to each other. A moving member 60 is located in a space formed between the pair of housings 10, 30 which includes a roller holder 61 and rollers 62. In the space is also located a wound flexible cable 50 having its winding direction reversed at a selected roller 62A. A through hole 70 is formed near a setting section 17 of the selected roller 62A in order to allow confirmation of the reversed location of the flexible cable 50.

Description

ROTARY CONNECTOR The present invention relates to a rotary connector built in a steering system of a vehicle in order to electrically connect a rotor-side electrical device and a stator-side electrical device.

Hitherto, there has been known a rotary connector disclosed, for example, in U. S. Patent No. 5,655,919. The disclosed rotary connector comprises a pair of housings concentrically disposed and relatively rotatably coupled to each other; a moving member accommodated in an annular space formed between the pair of housings; a roller holder and a plurality of rollers making up the moving member; and a flexible cable windably or rewindably accommodated in the space, a winding direction of the flexible cable being reversed at the rollers provided at the moving member. In the rotary connector, both ends of the flexible cable are electrically led out outwardly from each housing. One of the housings of the rotary connector is used as a movable member while the other of the housings thereof is used as a fixed member. When the movable housing rotates clockwise or counterclockwise, the flexible cable is wound or rewound in the space, so that electrical conduction at both ends of the flexible cable is maintained.

In general, this type of rotary connector is used as an electrical connecting means of, for example, air bag system or horn circuits by securing the fixed housing and the movable housing to a steering column of a steering system and a steering wheel, respectively, and connecting both ends of the flexible cable to a steering-column-side electrical device and a steering-wheel-side electrical device. Since, in the rotary connector, the winding direction of the flexible cable is reversed 180 degrees, the required length of this flexible cable can be shortened to about one-fourth that of a rotary connector in which the winding direction of the flexible cable is not reversed by 180 degrees and in which the flexible cable is wound in a single direction.

Therefore, the total cost of the rotary motor can be considerably reduced.

In one type of the rotary connector having the abovedescribed structure, after accommodating in the space the movable member having the flexible cable wound thereupon with a predetermined pattern, both ends of the flexible cable are led out to the outside through cable through holes formed in both housings. In another type of the rotary connector having the above-described structure, after the accommodation, a connecting connector, called a lead block, is connected to each end of the flexible cable. These two types of rotary connector are assembled by setting the connecting connectors in connecting connector setting sections formed in both the housings, and then by mounting a cover onto an open portion of the space to prevent the movable member from being dislodged therefrom.

A rotary connector is mounted to a steering system in order to be used as an electrical connecting means of, for example, air bag system or horn circuits, so that electrical conduction at both ends of the flexible cable need to be maintained either when the steering wheel has rotated clockwise from a neutral position to an end portion or when it has rotated counterclockwise from the neutral position to an end portion. In order to achieve this, it is, first, obviously necessary to form the flexible cable to a length that is long enough to allow absorption of the rotation of the steering wheel. On the other hand, it is necessary to keep the length of the flexible cable to a minimum to keep down costs of the rotary connector, when the movable housing is being made rotatable by equal amounts in a clockwise or counterclockwise direction from the neutral position.

Therefore, when the fixed housing, the movable housing, and the moving member are disposed at neutral positions relative to each other, the flexible cable needs to be wound upon a previously selected particular roller among the plurality of rollers provided at the movable member. In order to prevent shipping of rotary connectors in which neutral positions are shifted, it is necessary to confirm that the flexible cable is wound upon a particular roller.

Hitherto, a confirmation has been made as to whether or not a flexible cable is wound upon a particular roller by visual inspection from a gap between an open portion of a space and a roller holder of a moving member after accommodating, with the roller holder being faced upward, the moving member, having the flexible cable wound thereupon with a predetermined pattern, in the space.

However, since the gap between the open portion in the housings and the roller holder is narrow, it is not necessarily easy to make a confirmation as to whether or not the flexible cable is wound upon a particular roller by visual inspection. Thus, the conventional method does not allow highly efficient rotary connector assembly.

In recent years, in order to prevent or restrict the production of allophonic sounds from the rotary connector, the width of the roller holder of the moving member has tended to be made large. In this noise-eliminator type of rotary connector, after accommodation of the moving member in the space, it is in reality impossible to make a confirmation as to whether or not the flexible cable is wound upon a particular roller from the gap between the open portion of the space and the roller holder by visual inspection.

Accordingly, in order to overcome the above-described conventional problems, it is an object of the present invention to provide a highly reliable rotary connector which can be easily assembled and which allows easy confirmation as to whether or not a flexible cable is wound upon a particular roller of a moving member in a particular direction.

To this end, according to the present invention, there is provided a rotary connector comprising: a pair of housings concentrically disposed and relatively rotatably coupled to each other; a moving member which comprises a roller holder and a plurality of rollers, and which is to be accommodated in an annular space formed between the pair of housings; and a flexible cable windably or rewindably accommodated in the space, a winding direction of the flexible cable being reversed at a particular roller selected from the plurality of rollers; wherein a through hole is formed near a setting section of the particular roller in the roller holder in order to allow confirmation of a reversal location of the flexible cable.

Preferably, when a through hole is formed in a predetermined portion of the roller holder to allow confirmation of a reversal location of the flexible cable, a confirmation can be made as to whether or not the flexible cable is wound upon the particular roller from the back surface side of the roller holder even after completion of the assembly of one of the housings and the moving member. rherefore, it is possible to increase the efficiency with hich the rotary connector is assembled, so that a highly reliable rotary connector whose reversal portion is at the ? roper position can be provided.

Although only one particular roller is used and only me through hole is formed near the particular roller, the aumber of through holes and particular rollers is not Limited thereto. A plurality of flexible cables windably or rewindably accommodated in the space may be used, in which ase a plural number of particular rollers and through holes nay be provided and formed.

Although a through hole edge portion is formed in a roller-mounting-surface side and a back-surface side of the roller holder, at least the through hole edge portion formed in the roller-mounting-surface side may be chamfered in jrder to prevent damage to the reversal section of the flexible cable by preventing the formation of burrs.

When the rotary cable comprises a flexible cable, the roller holder may have a width that is larger than the diameters of the rollers mounted to the roller holder.

Although the present invention is applicable to any type of known rotary connector, it can be particularly effectively applied to this type of rotary connector whose roller holder has a width that is larger than the diameters of the rollers, and which does not allow easy confirmation of the reversal location of the flexible cable from the gap between the housings and the roller holder.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which : Fig. 1 is a plan view of an embodiment of the rotary connector.

Fig. 2 is a sectional view taken along line II-II of Fig. 1.

Fig. 3 is a partly cutaway plan view of a flexible cable.

Fig. 4 is a plan view of the embodiment of the rotary connector without the top plate.

Fig. 5 is a bottom view of the embodiment of the rotary connector without the bottom plate and the second housing.

Fig. 6 is a sectional view showing in detail the through holes formed in the roller holder.

As shown in Figs. 1 and 2, the rotary connector of the embodiment primarily comprises a first housing 10; a second housing 30 rotatably mounted to the first housing 10; flexible cables 50 that are windably/rewindably accommodated in an annular accommodating section 24, formed by combining both of the housings 10 and 30; and a moving member 60 rotatably disposed in the accommodating section 24.

The first housing 10 comprises a body 11 and a rotor snap 12 snappingly connected to a lower portion of the body 11. The body 11 comprises a top plate 14 that is donutshaped as viewed in a plane and that has a center hole 13 formed in a center portion thereof; and a first inner cylindrical member 15 extending downward from an inner peripheral portion of the top plate 14. The rotary snap 12 comprises a donut-shaped stopper plate 17, the donut shape having a diameter that is smaller than the diameter of the shape as viewed in a plane of the top plate 14 having the center hole 13 formed in the center portion thereof; and a second inner cylindrical member 18 provided in a standing manner from an inner peripheral portion of the stopper plate 17.

A plurality of stopper pawls 19a are formed so as to face inward at an inner peripheral surface of the first cylindrical member 15 in order to snappingly connect a plurality of stoppers 19, for bringing into contact with an end portion of the rotary snap 12, and the rotary snap 12.

By engaging each stopper pawl 19a with its corresponding stopper hole 20, each stopper hole 20 being formed in the rotary snap 12 in correspondence with its associated stopper pawl 19a, the rotary snap 12 is snappingly connected to the body 11. Two first connecting connector setting sections 21 are provided so as to protrude upward from predetermined locations in an upper surface of the top plate 14, and first connecting connectors 22 are accommodated and secured in the corresponding setting sections 17. In addition, an engaging recess 23 of the second housing 30 described in detail later is formed in a lower surface of an outer peripheral portion of the top plate 14.

On the other hand, the second housing 30 comprises an outer cylindrical member 31 and a bottom plate 32 snappingly connected to a lower portion of the outer cylindrical member 31.

The outer cylindrical member 31 is formed to provide a space 24 between the first inner cylindrical member 15 and the second inner cylindrical member 18 to accommodate flexible cables 50 and a moving member 60, and has a cylindrical form whose inside diameter is larger than the outside diameters of the first and second inner cylindrical members 15 and 18. At a top end portion of an inner peripheral surface of the outer cylindrical member 31 is formed a top-plate receiving section 34 with an annular, rod-like protrusion 33 for engaging the engaging recess 23 formed in the top plate 14, while at a bottom end portion of an outer peripheral surface is formed so as to face outward a plurality of stopper pawls 35 for snappingly connecting the bottom plate 32. A second connecting connector accommodating section 37 is formed at a portion (or the bottom end portion in Figs. 1 and 3) of the outer cylindrical member 31 in order to accommodate second connecting connectors 36.

The bottom plate 32 has a substantially flat shape with a center hole 38 formed therein. A stepped section 39 for accommodating an outer peripheral portion of the stopper plate 17 of the rotary snap 12 is formed at an inner peripheral portion along the center hole 38. In addition, an annular recessed groove 40 for engaging the moving member 60 is formed in the center portion of an upper surface of the bottom plate 34, and two second connecting setting sections 41 are formed so as to protrude downward at corresponding locations of the second connecting connector accommodating section 37 formed at a lower surface of the bottom plate 34. Connecting pins 36a of the second connecting connectors 36 are accommodated and secured in the corresponding setting sections 41. An annular outer peripheral wall 42 into which the outer cylindrical member 31 can be inserted is formed in a standing manner at an outer peripheral edge of the bottom plate 32, while stopper pawls 43 which engage the stopper pawls 35 for integration of the outer cylindrical member 31 are formed at the outer peripheral wall 42 at locations corresponding to the locations of the stopper pawls 35.

As shown in Fig. 3, flexible cable 50 consists of a plurality of electrical conductors 51 laminated with an insulating cover sheet 52, with each electrical conductor 51 being separately connected to pins 22a and 36a mounted to ends of the first and second connecting connectors 22 and 36, respectively. In the embodiment, as shown in Figs. 4 and 5, two flexible cables 50 are wound and accommodated in the accommodating section 24.

As shown in Figs. 2,4, and 5, the moving member 60 comprises an annular roller holder 61 which can be accommodated in the accommodating section 24; and a plurality of rollers 62 rotatably mounted to the roller holder 61.

As shown in Fig. 2, roller shafts 64 having stopper pawls 63 at inner surfaces thereof are formed so as to protrude from a roller setting section of the roller holder 61, with the cylindrical rollers 62, which are cylindrical in shape, being rotatably mounted to the roller shafts 64.

As shown in the same figure, the rollers 62 have cylindrical shapes and top plates. An inner cylindrical section 66, having stopper pawls 65 which can engage their corresponding stopper pawls 63, and an outer cylindrical section 67, being mounted to outer surfaces of the roller shafts 64, are concentrically formed at a center portion of a lower surface of the top plates so as to extend downward. Each roller 62 is mounted to its corresponding roller shaft 64 by inserting each roller shaft 64 between the inner cylindrical portion 66 and outer cylindrical portion 67, and engaging each stopper pawl 63 of its corresponding roller shaft 64 and each stopper pawl 65 of the inner cylindrical portion 66.

Protruding guide plates 68 for the flexible cables 50 are provided between the roller shafts 64 at the roller holder 61. Odd-shaped protrusions 69 are formed at predetermined intervals adjacent to particular rollers 62A, of the plurality of rollers 62, upon which are to be wound the flexible cables 50. These odd-shaped protrusions mark the positions of the particular rollers 62A. From portions near the roller shafts 64, to which the particular rollers 62A are mounted, to the protrusions 69 are formed through holes 70 used for determining whether or not the flexible cables 50 have been wound with predetermined orientations upon the particular rollers 62A. As shown in Fig. 6, chamfered sections 71 are formed at the edges defining the through holes 70. Each chamfered section 71 is used to eliminate the problem of the reversal sections of the flexible cables 50 being damaged as a result of burrs protruding into the accommodating section 24 during the formation of the through holes 70. The chamfered sections 71 may be formed only at a front surface side of the roller holder 61, that is, only at a surface to which the rollers 62 are mounted. Instead of having an oblique form as shown in Fig. 6, each chambered section 71 may have a circular form.

In Figs. 2,4, and 5, reference numerals 72 denotes resilient portions which engage the annular recessed groove 40 formed in the center portion of the top surface of the bottom plate 32. They are formed so as to substantially equally divide the roller holder 61. They are formed by forming cuts in the roller holder 61 in three directions and subjecting the free ends formed by the formation of the cuts to plastic deformation. Protrusions 73 which can engage the recessed groove 40 are formed at ends of bottom surfaces of the resilient portions 72.

A description will now be given of the method of assembling the rotary connector having the above-described structure and the advantages thereof.

The annular engaging recess 23 formed in the lower surface of the outer peripheral portion of the top plate 14 and the annular rod-like protrusion 33 formed at the top end portion of the inner peripheral surface of the outer cylindrical member 31 are made to coincide in order to form the body 11 of the first housing 10 and the outer cylindrical member 31 of the second housing 30 into an integral structure. This results in the formation of the space 24 between the body 11 and the outer cylindrical member 31, in which space 24 the flexible cables 50 and the moving member 60 are to be accommodated. The space has a Ushaped sectional shape and is annular as viewed in a plane.

The two flexible cables 50 are accommodated with required winding patterns in the space 24. Here, a reversal portion to be wound upon the particular rollers 62A at the moving member 60 is formed at a required portion of each flexible cable 50. After accommodating the two flexible cables 50 in the space 24, each first connecting connector 22, mounted to an end of its corresponding flexible cable 50, is accommodated and secured in its corresponding first connecting connector setting section 21 formed in the top plate 14; and each second connecting connector 36, mounted to the other end of its corresponding flexible cable 50, is accommodated and secured in the second connecting connector accommodating section 37 formed at the outer cylindrical member 31.

From above the flexible cables 50 accommodated in the space 24, each roller 62 provided at the moving member 60 is accommodated in the space 24, and the reversal portions of the flexible cables 50 are looped around the particular rollers 62A. The roller holder 62 of the moving member 60 is also accommodated in the space 24 and held by the body 11 of the first housing 10. When the above-described procedures are carried out, the assembly state shown in Fig.

5 results. In this assembly state, a confirmation is made as to whether or not each of the flexible cables 50 is wound upon the required particular rollers 62A from the through holes 70 formed in the roller holder 61 by visual inspection, In the moving member 60 used in the embodiment, the width of the roller holder 61 is larger than the diameter of each roller 62. Therefore, in the case where through holes 70 are not formed in the roller holder 61, after the accommodation of the flexible cables 50 and the moving member 60 in the space 24, it becomes extremely difficult or impossible to confirm the reversal position and direction of each flexible cable 50. In the rotary connector of the embodiment, through holes 70 are formed in predetermined locations in the roller holder 61, so that the abovedescribed problem is overcome. After the confirmation, if it is found that the flexible cables 50 are not wound upon the required particular rollers 62A, or that they are not wound in predetermined winding directions, the moving member 60, upon which the flexible cables 50 are wound, is taken out from the space 24 in order to correct the reversal locations and/or the reversal directions of the flexible cables 50.

Thereafter, the bottom plate 32 is mounted from below the outer cylindrical member 31, and the stopper pawls 35 formed at the lower end portion of the outer peripheral surface of the outer cylindrical member 31 and the engaging pawl 43 formed at the outer peripheral wall 42 of the bottom plate 32 are snappingly connected in order to form the outer cylindrical member 31 and the bottom plate 32 into an integral structure.

Lastly, the second inner cylindrical member 18 of the rotor snap 12 is inserted into the center hole 38 in the bottom plate 32 in order to accommodate the stopper plate 17 of the rotor snap 12 in the stepped section 39 of the bottom plate 32, and in order to bring the stopper pawls 19a formed at the body 11 of the first housing 10 into engagement with the stopper hole 20 formed in the second inner cylindrical member 18 of the rotor snap 12, whereby a completed rotary connector is formed.

In the rotary connector of the embodiment, through holes 70 are formed in predetermined portions of the roller holder 61 in order to allow confirmation of the reversal locations of the flexible cables 50. Therefore, even after completion of the assembly of the flexible cables 50 and the moving member 60 in the space 24, confirmation can be made as to whether or not the flexible cables 50 are wound upon the particular rollers 62A from the back surface side of the roller holder 61. Since the confirmation can be easily carried out, it is possible to increase the efficiency with which the rotary connector is assembled, and to provide a highly reliable rotary connector in which the reversal portions are at the proper locations.

In addition, in the rotary connector of the embodiment, two flexible cables 50 are wound upon the moving member 60, so that the rotary connector can be applied to an electrical circuit with many circuits.

Further, in the rotary connector of the embodiment, chamfered sections 71 are formed at the edge portions defining the through holes 70, so that the problem of the flexible cables 50 becoming damaged due to burrs occurring at the edge portions does not occur, whereby excellent durability and reliability are achieved.

The gist of the present invention consists in the formation of through holes 70 in predetermined portions of the roller holder 61 in order to allow confirmation of the reversal locations of the flexible cables 50. Other structures are not limited to those of the embodiment, so that various modifications may be made as necessary.

Preferably, a through hole is formed in a predetermined portion of the roller holder in order to allow confirmation of the reversal location of the flexible cable. Therefore, even after completion of the assembly of the flexible cable and the moving member in the accommodating section, a confirmation can be made as to whether or not the flexible cable is wound upon a particular roller from the back surface side of the roller holder.

Since the confirmation can be easily performed, it is possible to increase the efficiency with which the rotary connector is assembled, whereby a highly reliable rotary connector in which the reversal portion is at the proper location is provided.

A plurality of flexible cables may be wound upon the moving member, so that a rotary connector with many circuits can be provided.

When the rotary connector comprises a flexible cable, a chamfered portion may be formed on an edge portion defining the through hole, so that the problem of the reversal portion of the flexible cable becoming damaged as a result of burrs formed from the edge portion does not occur, making it possible to provide a highly durable and reliable rotary connector.

When a chamfered portion is formed on the edge portion defining the through hole, the movable member may be one in which the width of the roller holder, formed into an annular shape, has a width that is larger than the diameters of the rollers. While it is not possible when a through hole is not formed in the roller holder to confirm the position of the flexible cable after completion of the assembly of the flexible cable and the moving member in the accommodating section, it is possible to carry out this confirmation when a through hole is formed in the roller holder, and the confirmation can be carried out easily. Therefore, it is possible to assemble the rotary connector more efficiently.

In addition, the width of the holder can be set freely without reducing the efficiency of the assembly operation, so that the rotary connector can be designed more freely.

Claims

1. A rotary connector comprising: a pair of housings concentrically disposed and relatively rotatably coupled to each other; a moving member which comprises a roller holder and a plurality of rollers, and which is to be accommodated in an annular space formed between the pair of housings; and a flexible cable windably or rewindably accommodated in the space, a winding direction of the flexible cable being reversed at a particular roller selected from the plurality of rollers ; wherein a through hole is formed near a setting section of the particular roller in the roller holder in order to allow confirmation of a reversal location of the flexible cable.

2. A rotary connector according to Claim 1, wherein a plurality of flexible cables are windably or rewindably accommodated in the space, winding directions of the plurality of flexible cables being separately reversed at a plurality of particular rollers selected from the plurality of rollers; and wherein through holes are formed near setting sections of the plurality of particular rollers in the roller holder in order to allow confirmation of reversal locations of the flexible cables.

3. A rotary connector according to Claim 1 or 2, wherein of a through hole edge portion formed in a roller mounting-surface-side of the roller holder and a through hole edge portion formed in a back-surface-side of the roller holder, at least the through hole edge portion at the roller-mounting-side is chamfered.

4. A rotary connector according to Claim 2, wherein of the through hole edge portions formed in a rollermounting-surface side and a back-surface-side of the roller holder, at least the through hole edge portions at the roller-mounting-surface side of the roller'holder are chamfered.

5. A rotary connector according to any preceding claim, wherein the moving member used is one in which the roller holder, formed into an annular shape, has a width that is larger than the diameters of the rollers.

6. A rotary connector substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.