1. Field of the Invention
The present invention relaters to a rotary connector incorporated in a vehicular steering system and functioning to provide an electrical connection between an electric device disposed on the rotor side and an electric device disposed on the stator side.
2. Description of the Prior Art
This type of a rotary connector is mainly composed of a pair of housings disposed concentrically and connected together in a relatively rotatable manner and a flexible cable received in a windable and rewindable manner into a space formed between the paired housings. Both end portions of the flexible cable are fixed to the housings respectively and then are drawn out electrically to the exterior usually through lead wires. Of the paired housings, one is used as a movable housing and the other as a fixed housing. As the movable housing is turned clockwise or counterclockwise, the flexible cable is wound or rewound within the aforesaid space.
In the rotary connector thus constituted schematically, the fixed housing is fixed to a steering column of a steering system, while the movable housing is fixed to a steering wheel, and both ends of the flexible cable are connected respectively to an electric device disposed on the steering column side and an electric device disposed on the steering wheel side. In this state the rotary connector is used as an electrical connector means for, say, a air bag system or a horn circuit.
A rotary connector that has been becoming most popular in recent years is of the type in which, for facilitating and ensuring the connection between conductors carried within a flexible cable and lead wires connected to electric devices disposed on the steering column side and the steering wheel side, cable connectors called lead blocks are connected to end portions of the flexible cable and are fixed to a part of a fixed housing and a part of a movable housing, and external connectors connected to end portions of the lead wires are mounted to the lead blocks, thereby connecting the conductors carried in the flexible cable and the lead wires with each other electrically.
The vehicular steering system has recently become multi-functional, with consequent tendency to an increase in the number of circuits. However, if the tendency to such a multi-circuit configuration is promoted, the length of a lead block, if the lead block is of a mere single row arrangement of connecting terminals, becomes too large, causing an obstacle to its accommodation into a housing or giving rise to the problem that the size of a rotary connector used becomes large. In the conventional rotary connector, to cope with an increase in the number of conductors incorporated in a flexible cable, a plurality of lead blocks are connected to a single flexible cable or there is used a lead block with connecting terminals arranged in plural rows.
However, according to the former countermeasure just mentioned above, it is necessary that an end portion of the flexible cable be divided and that conductors carried in the thus-divided portions be connected to a plurality of lead blocks, while according to the latter countermeasure, it is necessary that an end portion of the flexible cable be divided and that conductors carried in the thus-divided portions be connected respectively to the plural rows in a single lead block. Thus, in both cases it is necessary to divide an end portion of the flexible cable and make connection to a lead block(s), but work for connection between the flexible cable and the lead block(s) is complicated. In the former case, moreover, since the number of lead blocks increases, the work for connecting lead blocks with external connectors after mounting the rotary connector to the steering system also becomes complicated.
The present invention has been accomplished for solving the above-mentioned problems of the prior art and it is an object of the invention to provide a rotary connector which, even with an increase in the number of conductors carried in a flexible cable, permits the work for connection between the flexible cable and lead blocks to be carried out easily and which also permits the work for connection between lead blocks and external connectors or external leads to be done easily.
According to the present invention, for achieving the above-mentioned object, there is provided a rotary connector comprising a pair of housings disposed concentrically and connected together in a relatively rotatable manner, a flexible cable received in a windable and rewindable manner within a space formed between the paired housings, and a lead block connected to an end portion of the flexible cable and held at a predetermined position of the housings, the lead block comprising a body portion, one or plural conductor extending portions projecting from the body portion, and an extending terminal portion, the body portion having a flexible cable connecting portion as a connection of conductors carried in the flexible cable and a group of connecting terminals integral with some of the conductors which constitute the connecting portion, the conductor extending portion(s) being integral with some of the remaining conductors which constitute the connecting portion, and the extending terminal portion having a connecting terminal or a group of connecting terminals integral with a conductor or a group of conductors which constitute the conductor extending portion(s).
In the rotary connector of the above configuration, even if the total number of connecting terminals formed in the lead block increases with an increase in the number of conductors carried in the flexible cable, this can be coped with by providing a predetermined number of connecting terminals in the body portion and also in the extending terminal portion and by bending the conductor extending portion and disposing the extending terminal portion at an appropriate position. Therefore, an end portion of the flexible cable can be connected to the lead block (a connection of the conductors carried in the flexible cable) in a simple manner without dividing the cable end portion. Besides, since the extending terminal portion is connected to the body portion through the conductor extending portion and it is possible to increase the total number of output terminals even without increasing the number of lead block. Therefore, there is no fear that the external connector mounting work or the external lead connecting work for the lead block may become complicated.
For example, if a plurality of connecting terminals are provided in the extending terminal portion, if the conductor extending portion is bent and the extending terminal portion is turned back along the body portion, and if the connecting terminal group projected in a row from the body portion and the connecting terminal group projected in a row from the extending terminal portion are arranged in parallel with each other, then not only it is possible to arrange two rows of connecting terminals in a single lead block but also it is possible to connect an end portion of the flexible cable to the flexible cable connecting portion of the body portion without dividing the cable end portion.
Preferably, the connecting terminals provided in the body portion and the extending terminal portion are integrally molded using an insulating resin. This is for facilitating their handling and for fixing their preset intervals with a high accuracy. Further, for facilitating the connection with external connectors, it is preferable that each connecting terminal group be projected at a predetermined certain pitch from the resin molded portion.
Preferably, a positioning means for positioning the extending terminal portion relative to the body portion is provided between the body portion and the extending terminal portion. According to this positioning means it is possible to establish, with a high accuracy, a positional relation between a connecting terminal or a group of connecting terminals projected from the extending terminal portion and a group of connecting terminals projected from the body portion at the time of folding back the extending terminal portion along the body portion.
For facilitating the connection of the flexible cable it is particularly preferred that a group of conductors in a number corresponding to the number of conductors carried in the flexible cable be arranged in the flexible cable connecting portion of the body portion flushly at intervals corresponding to the intervals preset for the conductors carried in the flexible cable.