FR3048944A1 - VEHICLE STEER CONNECTING WHEEL, WITH MEANS OF DELAYING ACTION - Google Patents

Abstract

A steering rod (BD) is intended to equip a vehicle front axle (TV), and comprises an intermediate portion (PI) extended by first (E1) and second (E2) ends adapted to be respectively coupled to a wheel ( RV) of the front axle (TV) and a steering rack (CD). This intermediate portion (PI) comprises delay means (MR) arranged to delay the action of the steering rod (BD) on the wheel (RV) relative to the action of the steering rack (CD) on the steering rod (BD), this delay being all the more important that the speed of realization of the action of the steering rack (CD) is small.

Description

The invention relates to vehicles comprising a front axle comprising wheels that can be oriented, and more precisely the steering rods that make it possible to orient the wheels of such vehicles.

Many vehicles, possibly of the automotive type, comprise a front axle in which each wheel can be oriented, via a coupling part (sometimes called wheel pivot), by a steering rod controlled by a steering rack. This coupling piece is also coupled via a ball joint to a support arm which is itself coupled via a pivot connection to a structural element of the vehicle, such as a cradle.

The steering rack is generally controlled by a steering wheel, and its arrangement and the arrangement of the steering rods define a constant mechanical reduction between the steering wheel angle and the steering angle (or orientation) of the wheels. In most motor vehicles of the general public type, this mechanical reduction is generally chosen in a range from fourteen to eighteen (it is then necessary to steer fourteen to eighteen times the steering wheel for a given wheel steering angle ). This constant mechanical gear ratio ensures moderate vehicle liveliness and safe driving. If we reduce this mechanical reduction, for example to a value equal to twelve or thirteen, or even smaller, to reduce the "flying stirring", the vehicle becomes noticeably more lively, and therefore at high speed it may seem unsafe for some drivers. The invention is in particular to allow an automatic adaptation of the gear according to the steering speed of the steering wheel.

It proposes for this purpose a steering rod, intended to be part of a vehicle front train, and comprising an intermediate portion extended (on both sides) by first and second ends adapted to be coupled respectively to a front wheel and steering rack.

This steering rod is characterized in that its intermediate portion comprises delay means arranged to delay its action on the associated wheel relative to the action of the steering rack on it, this delay being even more important than the speed of realization of the action of the steering rack is small.

Thus, the higher the steering speed of the steering wheel (and therefore a priori the lower the speed of the vehicle), the lower the ratio is low because the delay is small.

The steering rod according to the invention may comprise other features that can be taken separately or in combination, and in particular: its retardation means may be of the hydraulic type; its delay means may comprise a first body in which a first chamber is defined, and a second body mounted in translation, and in a sealed manner, in the first chamber and in which is defined a second chamber communicating with the first chamber via a first chamber; calibrated hole to allow a fluid exchange between these first and second chambers when the first body is translated relative to the second body by an action of the steering rack; The second body may comprise, inside the second chamber, in an area located opposite the calibrated hole, compensating means that are adapted to vary a fluid reception volume of the second chamber according to a quantity of fluid having entered the latter via the calibrated hole relative to an equilibrium position of the first chamber; the compensation means may comprise a part made of a compressible and elastic material; ❖ the compressible and elastic material may be an elastomer; Its delay means may comprise elastic return means installed in the first chamber between an inner face of the first body and an outer face of the second body, and clean, in the event of displacement of the first body inducing a reduction of a volume of receiving fluid from the first chamber relative to a fluid receiving volume in a balanced position, to allow automatic return of the first body in this equilibrium position; the elastic return means can be arranged in the form of a cylinder made of an elastic material; - Its delaying means can be installed just before the second end. The invention also proposes a vehicle, possibly of automotive type, and comprising a front axle comprising at least two wheels opposite to each other and orientable, and two steering rods of the type of the one presented above and coupled respectively wheels and steering rack. Other characteristics and advantages of the invention will appear on examining the detailed description below, and the accompanying drawings (obtained in CAD / CAD ("Computer Aided Design / Computer Aided Drawing"), of where the seemingly discontinuous character of certain lines), in which: - Figure 1 schematically illustrates, in a view from above, a straight portion of an example of the front axle of a motor vehicle, - Figure 2 illustrates schematically, in a view. in perspective, an exemplary embodiment of a steering rod according to the invention before it equips a front train, - Figure 3 schematically illustrates, in a sectional view, a subpart of an intermediate part. of the steering rod of Figure 2, comprising delay means, - Figure 4 illustrates schematically in a sectional view, the delay means of the intermediate portion of the steering rod of FIG. 3, placed in a first (equilibrium) position, and FIG. 5 schematically illustrates, in a sectional view, the means for retarding the intermediate portion of the steering rod of FIG. a second position (stop). The invention is intended to provide a BD steering rod intended to equip a TV front train of a vehicle.

In what follows, it is considered, by way of non-limiting example, that the vehicle is automotive type. This is for example a car. But the invention is not limited to this type of vehicle. It concerns indeed any vehicle comprising a front train comprising at least two wheels (right and left) opposite one another.

FIG. 1 schematically illustrates a straight portion of an example of a vehicle TV front train (here automotive type).

Each left or right part of the TV front axle comprises a support arm BS which is coupled, on the one hand, via a pivot connection (or articulation) LPB to a structural element ES of the vehicle, such as a cradle, and, d on the other hand, via a ball link to a coupling piece (not visible and sometimes called wheel pivot).

Furthermore, each left or right part of the TV front train comprises a steering rod BD according to the invention comprising an intermediate portion PI extended on either side by first E1 and second E2 opposite ends. The first end E1 of each steering rod BD is intended to be coupled to a ball joint RC whose tail is intended to be coupled to the coupling piece (or wheel pivot). The second end E2 of each steering rod BD is intended to be coupled to a steering rack CD which is itself controlled by the steering wheel of the vehicle.

As illustrated in FIGS. 2 to 5, the intermediate portion PI of each steering link BD, according to the invention, comprises delay means MR which are arranged to delay its action on the associated wheel RV with respect to the action exerts on it the steering rack CD. This delay is all the more important as the speed of realization of the action exerted by the steering rack CD on the steering rod BD is small.

In other words, the higher the steering speed of the steering wheel, the higher the speed at which the steering rack CD acts on the steering rod BD is high, and therefore the delay is small. However, the smaller this delay, the lower the reduction ratio and close to the minimum mechanical reduction resulting mainly from the respective arrangements of the steering rack CD and BD steering rods. Since the low steering speeds usually occur when the vehicle speed is high, it can therefore be deduced that, thanks to the invention, the gear ratio felt by the driver for low vehicle speeds is lower than that he feels for high speeds of the vehicle. vehicle, which ensures high speed at low speed and safe driving at high speed.

Note that in the example shown nonlimiting in Figures 2 to 5, the delay means MR are installed just before the second end E2. But in non-illustrated embodiments, the delay means MR could be installed just before the first end E1 or in an intermediate position between the first E1 and second E2 ends.

It will also be noted that the delay means MR may be of the hydraulic type.

In this case, they may, for example and as illustrated nonlimitingly in FIGS. 3 to 5, comprise damping means comprising first CA1 and second CA2 body.

A first chamber CH1 is defined in the first body CA1, and a second chamber CH2 is defined in the second body CA2.

Furthermore, the second body CA2 is mounted in translation, and in a sealed manner, in the first chamber CH1 and its second chamber CH2 communicates with the first chamber CH1 via a calibrated hole TC in order to allow a fluid exchange between the first CH1 and second CH2 chambers when the first body CA1 is translated relative to the second body CA2 by an action of the steering rack CD. It will be understood that the fluid is sealed in the respective home volumes of the first CH1 and second CH2 chambers. This fluid is for example an oil (optionally that used in the suspension dampers) or a gas (possibly nitrogen). The dimensions of the calibrated hole TC are adapted to the viscosity of the fluid used.

The second CA2 body being here secured to the rest of the intermediate portion PI which is indirectly coupled to the RV wheel, it is therefore initially immobile. Consequently, when the steering rack CD acts on the first CA1 body it initially induces its translation, here to the right along the arrow F1 of Figure 5, and therefore with respect to the second CA2 body which is initially immobile. The fluid reception volume of the first chamber CH1 gradually decreases, and therefore a portion of the fluid contained therein (CH1) enters the fluid reception volume of the second chamber CH2 via the calibrated hole TC. Then, at a given instant, the first body CA1 can no longer be translated relative to the second body CA2, so that the action exerted by the steering rack CD on the first body CA1 induces a simultaneous translation of the first CA1 and second CA2 body, and therefore an orientation (or a steering) of the associated RV wheel. It will be understood that the faster the first body CA1 is translated relative to the second body CA2, the faster it comes to a stop (illustrated in FIG. 5) and therefore the more rapidly it will translate the latter (CA2), and consequently the longer the delay. The action of the steering rod BD on the wheel RV is small compared to the moment when the steering rack CD exerts its action on the steering rod BD.

It will be noted that the translation between the equilibrium position (FIG. 4) and the stop position (FIG. 5) is preferably small. For example, it may be between 1 mm and 3 mm.

As illustrated without limitation in FIGS. 3 to 5, the second body CA2 may comprise inside the second chamber CH2, in an area which is located opposite the calibrated hole TC, compensation means MC which are clean. to vary the fluid reception volume of the second chamber CH2 according to the amount of fluid that has entered the latter (CH2) via the calibrated hole TC. This quantity of fluid transferred is considered in relation to the quantity of fluid that comprises the first chamber CH1 when it is placed in a position of equilibrium (or rest), illustrated in FIG. 4. This equilibrium position is that in which the first body CA1 is located when the vehicle is traveling in a straight line.

In the absence of such a variation of the fluid reception volume of the second chamber CH2, there would be no damping phenomenon if the fluid completely filled the respective reception volumes of the first CH1 and second CH2 rooms in the equilibrium position. However damping would be possible if the fluid did not completely fill the respective home volumes of the first CH1 and second CH2 chambers in the equilibrium position.

For example, and as illustrated without limitation in FIGS. 3 to 5, the compensation means MC may comprise a part made of a compressible and elastic material. In this case, the compressible and elastic material may, for example, be an elastomer or a rubber, possibly synthetic.

It will be noted, as shown in non-limiting manner in FIGS. 3 to 5, that the delay means MR may advantageously comprise elastic return means MRE installed in the first chamber CH1 between an inner face of the first body CA1 and an outer face of the second body CA2. These elastic return means MRE are clean, in case of displacement (translation) of the first body CA1 inducing a reduction of the fluid reception volume of the first chamber CH1 relative to its fluid reception volume in the position of balance, to allow automatic return of the first body CA1 in the equilibrium position.

For example, and as illustrated nonlimitingly in FIGS. 3 to 5, these elastic return means MRE can be arranged in the form of a cylinder made of an elastic material. This elastic material may, for example, be an elastomer or a rubber, which may be synthetic.

In this case, the elastic cylinder MRE may, for example, be fixedly secured to the inner face of the first body CA1 and the outer face of the second body CA2. This fixed attachment is preferably by adhesion. The latter may, for example, result from a force fit around the second body C2.

In the presence of such a fixed fastening on the two inner and outer faces, the elastic cylinder MRE works in shear when the first body CA1 is translated relative to the second body CA2 (here to the right (arrow F1)), as shown in FIG. In other words, it stretches to the right, and therefore its elasticity allows it to automatically resume the initial shape that it has in the equilibrium position (in which it is not constrained in shear (or stretched).

It will be noted that such elastic return means MRE also advantageously ensure the sealing of the first chamber CH1 and thus the delay means MR, and give the steering link BD some flexibility.

It will also be noted that the first CA1 and second CA2 bodies are preferably made of a rigid material. The latter may, for example, be a metal, such as for example a steel, or a plastic material, such as for example a thermoplastic.

It will also be noted that the first CA1 and second CA2 bodies are preferably of circular cylindrical shape. But alternatively they could have a cylindrical shape with square or rectangular section, for example.

Claims (10)

1. steering rod (BD) for a vehicle front train (TV), said steering rod (BD) comprising an intermediate portion (PI) extended by first (E1) and second (E2) ends adapted to be coupled respectively a wheel (RV) of said front axle (TV) and a steering rack (CD), characterized in that said intermediate portion (PI) comprises delay means (MR) arranged to delay an action of said steering link ( BD) on said wheel (RV) with respect to an action of said steering rack (CD) on said steering link (BD), said delay being all the more important as the speed of realization of said action of the rack of direction (CD) is small. 2. Steering link according to claim 1, characterized in that said delay means (MR) are of the hydraulic type. 3. steering linkage according to claim 2, characterized in that said delay means (MR) comprises a first body (CA1) in which is defined a first chamber (CH1), and a second body (CA2) mounted in translation, and in a sealed manner, in said first chamber (CH1) and in which is defined a second chamber (CH2) communicating with said first chamber (CH1) via a calibrated hole (TC) to allow a fluid exchange between said first chamber (CH1) and second (CH2) chambers when said first body (CA1) is translated relative to said second body (CA2) by an action of said steering rack (CD). 4. steering linkage according to claim 3, characterized in that said second body (CA2) comprises inside said second chamber (CH2), in an area situated opposite said calibrated hole (TC), means compensation means (MC) adapted to vary a fluid reception volume of said second chamber (CH2) as a function of a quantity of fluid having entered the latter (CH2) via said calibrated hole (TC) with respect to a equilibrium position of said first chamber (CH1). 5. Steering link according to claim 4, characterized in that said compensating means (MC) comprise a part made of a compressible and elastic material. 6. Steering link according to claim 5, characterized in that said compressible and elastic material is an elastomer. 7. steering link according to one of claims 3 to 6, characterized in that said delay means (MR) comprises elastic return means (MRE) installed in said first chamber (CH1) between an inner face of said first body (CA1) and an outer face of said second body (CA2), and clean, in case of displacement of said first body (CA1) inducing a reduction of a fluid reception volume of said first chamber (CH1) relative to a fluid receiving volume in a position of equilibrium, to allow automatic return of said first body (CA1) in said equilibrium position. 8. Steering link according to claim 7, characterized in that said elastic return means (MRE) are arranged in the form of a cylinder made of an elastic material. 9. Steering link according to one of claims 1 to 8, characterized in that said delay means (MR) are installed just before said second end (E2). 10. Vehicle comprising a front axle (TV) having at least two wheels (RV) opposite to each other and orientable, characterized in that said front axle (TV) further comprises two steering rods (BD) according to one of the preceding claims, and respectively coupled to said wheels (RV) and a steering rack (CD).