EP1324437B1 - Turnable contact including an external device to mechanically put tension on the cable - Google Patents

Description

The present invention relates to a device ensuring the connection electric between two bodies respectively fixed and mobile animated by relative rotational movement.

Such devices, also called rotary contacts, are especially employed in the automotive industry, in the columns steering to allow the electrical connection between elements located in the steering wheel, and therefore mobile in rotation, and a fixed circuit wired into the passenger compartment of said vehicles. Well that there are many other possible applications of these devices, the example of the steering columns will be used as preferential in the following description, to facilitate reading in enlightening it with this particular application. Such a device is described in document US-A-5865634, considered to be the closest state of the art.

The known and used rotary contacts in this field are configured in such a way that the fixed part and the mobile part define between them an annular space of axis coincident with the axis of rotation, in which a flexible flat cable is spirally wound carrying several conductive lines. This annular space comprises in particular two walls of parallel appearance to the axis of rotation to which the two ends of the ribbon cable are fixed.

In this type of configuration, the flexible cable invests differently space in particular according to the direction of rotation. So, in a first sense, it is wound around the central part of the rotary contact. In the other direction of rotation, it loosely wraps around the external peripheral wall of the device. In any case, it does not no particular guidance and its movement, especially in directions radial, is hardly controlled. To properly perform its function, it is in fact practically never stretched in the annular space which houses it.

On the other hand, it is subject to constant stresses, notably due to rotational movements of one party relative to the other, including speed, frequency and amplitude depend on the movement printed on the steering wheel. These constraints, applying to various portions of the flexible cable, may cause vibrations or noises that cannot be controlled, due to the absence of any guide element for the moving cable.

To solve this problem, which leads to hearing discomfort for the occupants of the vehicle, it was proposed to include in the annular space a part in particular intended to partially fill it, to prevent as far as possible possible any parasitic movement of the cable during its winding phases / unwinding. This part occupies almost the entire annular space, and has a radial-shaped slot allowing the passage of the cable from one to the other of the walls to which its ends are fixed. It effectively ensures guidance, since the residual spaces for winding / unwinding the cables, located on both sides of said room, are much smaller and do not in particular allow more radial movements of certain sections of the cable, typically generating noise and vibration.

The interposition of such a part also makes it possible to significantly reduce the cable length required, due to its influence on the difference in winding diameters / unwinding of the flat cable in its different phases Operating. Mechanical contacts with the walls of the annular space are consequently reduced, as well as the friction due to the flexible cable.

In other words, the interposition of such an intermediate piece allows the noise reduction, essential for an accessory located near the driver, and a substantial reduction in the length of the ribbon cable flexible, facilitating its mounting between the fixed and mobile parts, and lowering its production costs as well as those of the rotating contact.

This intermediate piece is driven along a circular path by the flexible cable, whatever the direction of rotation of the movable part relative to the fixed part. This training is done by sliding said piece in space annular, slip which, however, also generates noise when poorly controlled, in particular due to the inevitable friction produced in contact with the support.

The objective of the present invention is to propose a system which decreases by even more importantly the residual noise, in particular allowing a improved control of the movement of all moving parts between the fixed part and the moving part.

Secondarily, the system of the invention makes it possible to further reduce the cable length, which goes in the direction of further attenuation of noise, and has a favorable economic impact on its manufacture.

To fulfill these objectives, and others which will become apparent in the rest of the description, the device of the invention, provides the electrical connection between two bodies respectively internal and external, one of which is fixed and the other mobile in rotation relative to the first, said bodies defining between them a space in which at least one flat flexible electrical cable is arranged, the ends of which are fixed respectively to the external body and to the internal body, the latter being cylindrical in shape so that the electric cable can alternately be there wind or unwind in the direction of rotation, said space comprising means for keeping the cable in the stretched state whatever its degree winding.

According to the invention, the means for maintaining the cable in the stretched state, comprise a mobile carriage guided in said space along a predetermined path, connected to the external body via return means, comprising at least one return stud cooperating with at least one return stud fixed to said space to create by successive changes of direction a path of variable length for the cable, which cooperates alternately with a pad of the carriage and a fixed pad.

This is an aspect which is not mentioned in the devices of the prior art, in which the emphasis is rather on reducing the latitude space of said flexible cable. This one is made less noisy there because it has less freedom of displacement in a direction other than that which its function commands it (winding / unwinding along a circular path). However, the nature of devices interposed in the prior art between the fixed and mobile parts does not allow not to stretch the flexible cable correctly, whatever the direction of relative rotation of said parts.

The advantage presented by the device of the invention is twofold: first, the tension maintained substantially constant allows no lateral movement interference when moving the cable, and secondly, the existence of these means of maintaining the tension allows the use of a configuration which reduces significantly the length of the cable.

According to one possibility, said means comprise a mobile carriage guided in the space between the internal and external bodies along a predetermined path, connected to the external body via return means, and comprising at least one stud return cooperating with at least one return stud fixed to said space to create by successive changes of direction a path of variable length for the cable, which cooperates alternately with a pad of the carriage and a fixed pad.

This path adapts at any time to the unwound length of the cable, thanks to the existence of means of recall which make it possible to absorb, in a sense or in the other, any variation in length unwound. The existence of return studs, fixed and mobile, makes it possible to extend the duration of the journey in a limited space, which is defined by the respective forms of the internal and external bodies.

Preferably, the carriage is guided in translation along a steering axis tangential to the internal body.

This means that, unlike most prior art systems, the configuration of the device of the invention has no symmetry of revolution. The space defined between the internal body and the external body is not annular, and the external part can take a prismatic configuration, which depends on made of the cable tensioning system on the one hand, and criteria of implantation of the rotating contact on a column top on the other hand.

According to an advantageous configuration, the studs are free to rotate respectively with respect to said space, and with respect to said carriage, forming made of cable return pulleys.

The latter is then additionally accompanied in rotation during each change of direction. This additional guidance reduces the friction and therefore of the forces exerted on the cable, forces that this configuration already naturally tends to minimize, due to the existence of different pulleys reference which divide the total tension applied to the cable.

Preferably, the return means consist of a tension spring. The means for maintaining the tension of the cable are then simply constituted by a carriage movable in translation between two extreme positions, recalled in one rest position via said tension spring. This trolley has studs or pulleys around which the cable changes direction, the cable path between two successive pulleys of the carriage passing through a pulley fixed to the fixed body, for example on its bottom.

Preferably, it is possible to provide a fixed pulley between the internal part and an input pulley of the mobile carriage.

More preferably, the studs are two in number arranged at the same time the bottom of the space defined between the internal and external bodies, and on the carriage.

For a cable length allowing a vehicle steering wheel automobile to make a few turns in one direction and in the other, a configuration to four studs or pulleys does not require too much volume for the device of the invention, said volume in fact remaining compatible with the constraints linked to the location of the vehicle in which the rotary switch is to be fitted.

According to one possibility, the internal body has an annular shape comprising a radial recess in which the flexible cable is fixed according to a radial direction, the portions connecting the walls of said recess and the wall outer peripheral of the inner body being rounded.

This configuration allows the cable to be wrapped around the annular internal body in both directions, which is never the case in art devices prior. This possibility of winding in both directions makes it possible not to use a minimum cable length, since it allows symmetry of operation. The rounded junction between the radial slot and the peripheral wall exterior allows you to initiate winding, in both directions, without special constraints apply to the cable.

According to another important advantage, the cart of the device of the invention includes a marking capable of being positioned opposite detection means secured to the external body, when the flexible cable is in a configuration allowing displacement of the same amplitude in both directions of rotation.

These means make it possible to detect the neutral position of the steering wheel, that is to say the one for which the steered wheels are aligned on the longitudinal axis of the vehicle. This marking is located in a location such that it is positioned opposite said detection means, when the flexible cable has been completely unwound, and is about to be rewound around the inner part, in the same direction of rotation.

Preferably, the ends of the flat cables are provided with connectors facilitating their attachment to the fixed and mobile body.

The device of the present invention is particularly advantageous because its almost symmetrical operation in both directions of rotation allows use a fairly short flexible cable. Cable tension maintenance combined with proper guidance of the carriage in the space between the internal body and the body in addition, virtually eliminates any extraneous noise during the operation of the rotary contact.

• la figure 1 représente schématiquement le corps interne auquel est fixée l'extrémité du câble flexible, et sa relation avec le chariot de maintien en tension dudit câble ;
• la figure 2 reprend les éléments de la figure 1, mais dans une autre position relative du corps interne et du chariot ;
• la figure 3 est une vue en perspective éclatée schématique des différents éléments constituant le dispositif selon l'invention.

The invention will now be described in more detail, with reference to the figures for which:

• FIG. 1 schematically represents the internal body to which the end of the flexible cable is fixed, and its relation to the carriage for maintaining the tension of said cable;
• Figure 2 shows the elements of Figure 1, but in another relative position of the internal body and the carriage;
• Figure 3 is a schematic exploded perspective view of the various elements constituting the device according to the invention.

With reference to FIG. 1, the annular body (1) represents the internal body of the device of the invention, which is - in the configuration shown - a rotor movable in rotation relative to an axis (A). In a contact application automobile steering column turn, said annular body (1) is mounted secured to the steering column (not shown).

The rotation of the steering wheel (not shown) is therefore reflected in this annular part (1), which performs the winding, in one direction or the other according to the rotational movement printed on the steering wheel, of a flexible electric cable flat (2) which is secured to it via a connector (4).

The other end of this cable (2) is fixed to the external fixed body (not shown) via a connector (5). The path followed by this flexible cable (2) between the two connectors (4, 5) pass through a number of pulleys or studs reference (7, 7 ', 8, 9) at which it changes direction. This structure allows in particular to store the length of cable unwound in a small perimeter. This is particularly the case in the representation of FIG. 1, in which almost all of the cable is unwound from the annular part (1).

Two of the pads or pulleys (7, 7 ') are mounted on a mobile carriage (3) in translation in a direction tangential to the rotation of the annular part (1). This carriage (3) is guided in its rectilinear movement, as will be shown in more detail with reference to Figure 3. At one of its ends, it has a tension spring (6) which returns it to its rest position, corresponding to a neutral position of the steering wheel which is approximately that of the representation of figure 1.

When the flexible cable (2) is wound around the annular part (1), by rotation of said part around the axis (A), as shown in FIG. 2, the cable path (2) outside of said part (1) is shortened, causing the compression of the spring (6).

The two studs (8, 9) are arranged fixed relative to the contact frame rotating, that is to say relative to the bottom (12) of the fixed external part (11) (see figure 3).

This structure allows winding around the annular part (1) in the two possible directions of rotation. Thus, the outer borders (10, 10 ') of the radial slot in which the connector (4) is arranged are rounded, so as to allow the cable to be guided without constraint flexible (2) in these two directions.

Figure 3 shows more precisely the structure of the different elements that make up the invention. Thus, the fixed external body (11) of the device the invention is partially represented, by means of its bottom (12) and two walls (13, 13 '). This body (11) has a parallelepipedal appearance, which is unusual for a rotating contact. The reason for this is notably that it houses a number additional elements for guiding and maintaining tension in the cable.

The annular part (1) is notably guided therein via a bearing (14) in which it is free to rotate. This rotation is carried out under the impulse of the column of steering (not shown) secured to said part (1) at its orifice central crossing. The carriage (2) movable in rectilinear translation is L-shaped, one of the branches of which is guided by pins (15, 16) aligned at the end unciform, as well as by a slide (16) in which slides a protuberance (not visible) of said branch. This slide (16) defines the entire path straight of the carriage (2). At the end of its other branch, the latter comprises a raised edge (17) guided in an inverted L-shaped slide (18).

The spring (6) is fixed on the one hand in the first branch of the carriage (2), and on the other hand, at its free end, to a wall (not shown) of the fixed body (11). The carriage (2) further supports two pins (19, 20) for fixing the studs (7, 7 '). Similarly, the bottom (12) of the fixed body (11) has two pins (21, 22) for fixing the studs (8, 9). These different pawns (18 to 22) are designed so that their associated stud can be clipped onto it without tools. They are so separated into two symmetrical axial portions, coming in one piece with the body supporting them, made of elastic plastic so that the two symmetrical branches can move towards each other at the time of clipping of the studs (7, 7 ', 8, 9).

As seen with reference to the previous figures, the connector end (4) is plugged into a radial slot (23) formed in the body annular (1). Conductors protected by overmolding (24, 24 ') allow the electrical connection between the flexible cable (2) and arranged electrical elements in the steering wheel.

The connector (5) fitted to the other end is plugged into a recess (25), and electrically connected to the wiring fitted to the rest of the vehicle.

The above description is only one possible example of setting work of the invention, which is by no means exhaustive thereof. The invention encompasses on the contrary all the variants of shapes and configurations which are within reach of those skilled in the art.

Claims (8)

1. Device ensuring the electrical connection between two bodies, internal (1) and external (11) respectively, of which one is fixed and the other mobile in rotation in relation to the first, said bodies (1, 11) defining between them a space in which is arranged at least one flat flexible electrical cable (2), the ends of which are connected to the external body (11) and the internal body (1) respectively, the latter being cylindrical in form such that the electrical cable (2) can either wrap around this or unwrap from this depending on the direction of rotation, said space comprising means (3, 6, 7, 7', 8, 9) to hold the cable (2) in its tensioned state whatever the degree of winding, characterised in that said means comprise a mobile carriage (3) guided in said space on a predetermined path and linked to the external body (11) via return means (6) comprising at least one return stud (7, 7') co-operating with at least one return stud (8, 9) fixed on said space to create, by successive changes of direction, a path of variable length for the cable (2) which co-operates alternately with a stud (7, 7') of the carriage and a fixed stud (8, 9).
2. Device ensuring the electrical connection between two bodies (1, 11) with a relative rotation movement according to the previous claim, characterised in that said carriage (3) is guided in translation along a direction axis tangential to the internal body (1).
3. Device ensuring the electrical connection between two bodies (1, 11) with a relative rotation movement according to claim 1 or claim 2, characterised in that the studs (7, 7', 8, 9) are free to rotate in relation to the space defined by the internal body (1) and external body (11) respectively and in relation to said carriage (3), thus forming cable return pulleys (2).
4. Device ensuring the electrical connection between two bodies (1, 11) with a relative rotation movement according to any of the previous claims, characterised in that the return means comprise a traction spring (6).
5. Device ensuring the electrical connection between two bodies (1, 11) with a relative rotation movement according to any of claims 1 to 4, characterised in that the studs (7, 7', 8, 9) are two in number arranged both on the base (12) of the space created between the internal and external bodies, and on the carriage (3).
6. Device ensuring the electrical connection between two bodies (1, 11) with a relative rotation movement according to any of the previous claims, characterised in that the internal body (1) has an annular form comprising a radial recess (23) in which the flexible cable (2) is fixed in a radial direction, the parts (10, 10') linking the walls of said recess (23) and the external peripheral wall of the internal body (1) being rounded.
7. Device ensuring the electrical connection between two bodies (1, 11) with a relative rotation movement according to any of claims 1 to 6, characterised in that the carriage (3) comprises a marking positioned opposite detection means of one piece with the external body (11) when the flexible cable (2) is in a configuration allowing a movement of the same amplitude in both directions of rotation.
8. Device ensuring the electrical connection between two bodies (1, 11) with a relative rotation movement according to any of the previous claims, characterised in that the ends of the flat cables (2) are fitted with connectors (4, 5) facilitating their fixing to the fixed body (11) and mobile body (1).

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