FR2843931A1 - Motor vehicle steering rack pressure balancer has air-permeable water repellent plugs in corrugated boot end ring holes - Google Patents

Abstract

The pressure balancer for a motor vehicle steering rack (3) with a tubular housing connected to axial pivots (9) by flexible corrugated boots (7) and rings (8) has holes (11) in the rings or crowns fitted with plugs (13) of an air-permeable but water-repellent material to balance the air pressures inside and outside the housing. The pressure balancer for a motor vehicle steering rack (3) with a tubular housing connected to axial pivots (9) by flexible corrugated boots (7) and rings (8) has holes (11) in the rings or crowns fitted with plugs (13) of an air-permeable but water-repellent material to balance the air pressures inside and outside the housing. The plugs can be fixed in place by adhesive, welding, crimping or simple pressure fitting. Alternatively, the ring or crown itself can be made at least partially from such material.

Description

The present invention generally relates to systems

  steering for motor vehicles. It relates, more particularly, to rack and pinion directions, whether or not provided with an assistance device.

  Even more specifically, the invention relates to a device which, for this kind of steering, ensures a balancing between the air pressures inside the steering and the outside of the latter.

  A rack-and-pinion steering system for a motor vehicle is usually implemented in a completely sealed manner, in order to avoid any undesirable entry of water or moisture inside the steering system. This however poses problems of overpressure or depression in the direction, depending on the increase or decrease in the surrounding temperature, and / or the

  air temperature in the direction.

  In particular, the steering bellows, which usually cover and protect the end regions of the rack and the "axial" ball joints of the connecting rods, undergo deformations due to pressure variations between the interior and the outside. These deformations themselves lead to more or less rapid deterioration or destruction

bellows.

  To avoid such deformations and their harmful consequences, it has already been proposed to allow an entry of air in the direction, or conversely an exit of air, so as to make the direction "breathable", avoiding as much as possible an unwanted entry of water, or other liquids, or even dust. A known solution consists in making directions with "breathable" bellows, which allow the entry or exit of air. 25 However, this solution requires special manufacturing, which is therefore complex and

coteuse, bellows themselves.

  The present invention aims to provide a simple and economical device for balancing the pressures between the inside and the outside of the

  steering, in order to avoid deformation and deterioration of the bellows.

  To this end, in the device according to the invention, the balancing of the pressures between the inside and the outside of a rack-and-pinion steering of a motor vehicle, in which the rack is housed and slidably mounted in a main casing or tube steering, the ends of the rack being coupled to rods by means of "axial" ball joints, the end zones of the rack and the "axial" ball joints being covered by bellows connected respectively to the two ends of the tube or casing, it is provided that each bellows is connected to the pivot of the corresponding "axial" ball joint by means of a ring or crown mounted between the pivot, which passes through it at its center, and the end of the bellows, linked at its periphery, the ring or crown comprising at least one orifice closed by a member made of a material permeable to air but hydrophobic, or this ring or crown is ant itself produced, at least partially, in one

  breathable but hydrophobic material.

  In one embodiment of the invention, the ring or crown, mounted between the pivot of the "axial" ball joint and the end of the bellows, comprises one or more orifices which open out inside the bellows, and in which

  are placed pellets of breathable but hydrophobic material.

  The tablet (s), breathable but waterproof,

  or the analogous constituent material of the ring or crown itself, allow the entry of air inside the bellows, or the exit of air out of these bellows, while preventing undesirable entry of water .

  A device is thus obtained which makes the steering "breathable", so as to avoid the deformation of its bellows and their deterioration, without complicating the structure of the bellows or their mounting, and even by simplifying this mounting. Indeed, the presence of the ring or crown, mounted around the pivot of the "axial" ball joint, avoids having to carry out, as is customary, a

  annular groove in said pivot, in order to fix the bellows.

  The invention will in any case be better understood using the

  description which follows, with reference to the appended diagrammatic drawing representing, by way of example, an embodiment of this pressure balancing device:

  Figure 1 is a partial exterior view of a rack and pinion steering provided with the device object of the invention; Figure 2 is a detail view, in longitudinal section, passing through one of the bellows in this direction and through the associated pressure balancing device; Figure 3 is a cross-sectional view of this device, according to

line 111-111 of figure 2.

  Figure I externally shows a direction I rack, which in the example illustrated is a manual direction. This figure shows more particularly the central tubular tube or casing 2 of the steering 1, in which is housed and slidingly mounted the rack 3. The rack 3 is engaged with a rotary pinion, linked in rotation to the steering column (not

  shown), the entry of the movement being in 4.

  The right and left ends of the rack 3, external to the tube or casing 2, are coupled to connecting rods 5, by means of 5 "axial" ball joints 6. Two bellows 7, connected respectively to the two ends of the tube or casing 2 , cover and protect end areas

  of the rack 3 and the ball joints 6, as well as partially the rods 5.

  As shown more particularly in Figure 2, the outer end of each bellows 7 is connected via a ring 8 10 to the pivot 9 of the corresponding "axial" ball 6. The pivot 9 passes through the central opening 10 of the ring 8, which is thus immobilized on this pivot 9. The end

  outside of the bellows 7 is linked to the circular periphery of the ring 8.

  The ring 8 has a plurality of holes 11 (in the illustrated example four holes 11 - see also Figure 3), which are drilled between the interior volume 12 of the bellows 7 and the exterior. In each orifice 11 is placed, and retained, a filter pad 13 made of air permeable, but hydrophobic material. Thus, a balancing of the air pressures is carried out between the interior volume 12 of the bellows 7, therefore the interior of the direction 1, on the one hand, and the exterior space, on the other hand, while preventing the water and 20 dust entry in direction 1. Thus, depending on temperature variations, the air

  can exit or enter direction 1, so as to balance the pressures between the inside of this direction and the outside, in order to avoid the deformation of the bellows 7 and their deterioration, in particular when the surrounding temperature rises or falls sharply , however, the passage of water and moisture is avoided.

  The constituent material of the pellets 13, permeable to air but hydrophobic, can be a porous fluoropolymer resin, such as that sold under the name "PERMEON" (registered trademark), or

any other equivalent material.

  The invention is particularly applicable to manual or power steering, the tube or housing 2 of which "naturally" provides

  communication between the regions of two bellows 7.

  It goes without saying that the invention is not limited to the sole embodiment of this pressure balancing device which has been described above, by way of example; on the contrary, it embraces all of the variant embodiments and applications respecting the same principle. Thus, in particular, that we would not depart from the scope of the invention: - by providing, in the ring 8, a single orifice 11, or orifices in any number, and with a corresponding number of pastilles 13; - By replacing these pellets 13 with any similar element, such as membrane or plug, made of breathable but hydrophobic material, and fixed by any suitable means, such as bonding, welding, crimping, snap-fastening or simple mounting by pressure; - by giving any shape to the ring 8, or by replacing it with a similar piece such as a crown; - By making this ring or crown itself, at least partially, in a material permeable to air but hydrophobic;

  - by choosing any material with such properties.

Claims (3)

  1. Device for balancing the pressures between the interior and the exterior of a rack and pinion steering system of a motor vehicle, in which the rack and pinion (3) is housed and slidably mounted in a main casing or steering tube (2) , the ends of the rack (3) being coupled to rods (5) by means of "axial" ball joints (6), the end regions of the rack (3) and the "axial" ball joints (6) being covered by bellows (7) connected respectively to the two ends of the tube or casing 10 (2), characterized in that each bellows (7) is connected to the pivot (9) of the corresponding "axial" ball joint (6) by the 'intermediary of a ring or crown (8) mounted between the pivot (9), which crosses it in its center (10), and the end of the bellows (7), linked to its periphery, the ring or crown (8 ) comprising at least one orifice (11) closed by an element (13) made of a material permeable to 15 l air or hydrophobic, or this ring or crown (8) being produced itself,   at least partially, in a material permeable to air but hydrophobic.   2. Pressure balancing device according to claim 1, characterized in that the ring or crown (8), mounted between the pivot (9) of the "axial" ball joint (6) and the end of the bellows (7 ), comprises one or more orifices (11) which open into the interior (12) of the bellows (7), and into which are   disposed with pellets (13) of air permeable but hydrophobic material.   3. Pressure balancing device according to claim 2, characterized in that the material of the pellets (13) is a resin porous fluoropolymer.