Steering control for self-propelled vehicles

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 of Swiss Patent Application No. 01275/04 filed Jul. 29, 2004 and of Swiss Patent Application No. 00256/05 filed Feb. 15, 2005, the disclosures of which are expressly incorporated by reference herein in their entireties.

The present invention concerns a steering control for self-propelled vehicles, such as motorcycles, automobiles, etc., according to the preamble of the claim 1.

A steering control device of the type mentioned is described in detail in the EP121691 1A2 filed by the same applicant. This preceding patent application thus constitutes the state of the art pertaining to the present invention, which aims at presenting an improvement of the same. The entire contents of the EP1216911 A2 thus is integrated into the description of the present patent application.

The EP-1216911A2 describes and shows a steering control in of a steering wheel of an automobile, or of a handlebar of a motor cycle, provided with a gripping zone of elastically variable geometry, inside which a pneumatic, or a hydraulic, sensor is located, which reacts to changes o the form and/or to the volume of the gripping zone. The sensor according to the invention is connected to at least one control element and/or to a device monitoring the functionality of the vehicle in such a manner that the safety control device is activated by the reaction of the sensor.

Practical realisation of the concept described in the EP-1216911A2 led to the experience that this concept calls for improvements that considerably increase the driving safety of the vehicle. Such improvements thus are the objective of the present invention.

A first finding from practical experience indicates that only pneumatic sensors, and still better, hydraulic sensors, present reliable functionality as they permit—other than the ones using electrical micro-switches reacting to elastic deformation of the steering control, as already known from the general state of the art—picking up an analogue signal of the pressure exerted by the hand onto the steering wheel or onto the handlebar. A signal of this type presents the great advantage over a signal of digital open/closed type emitted by an electric switch, of reproducing in simple but correct form—without complex electronic devices—the quality of the reactions of the driver, which means that the degree of his fear or his panic induced by unexpected and unforeseeable situations he finds himself exposed to. The objective of the present invention, just as the one of the EP-121691 1A2, is to create a steering control for vehicles, which is capable of improving the preventive and active safety of the driver of the vehicle, as well as of the other users of the road—pedestrians in particular—owing to the considerable reduction in the reaction time lag of the driver, and correspondingly shortening the length of the braking distance. A few meters difference in the braking distance can prove vital in avoiding a crash, or in reducing the effects of a crash. This is confirmed every day on the road. On the other hand it is known that in the case of unexpected danger situations (pedestrians or animals unexpectedly crossing the road, obstacles appearing suddenly after a curve, sudden left turns by a cyclists, etc.) the driver, according to a first form of reaction, instinctively tends to grip the wheel or the handlebar with greater or lesser force and speed in function of the degree of panic he suffers. Another form of reaction, often seen in practical traffic, and differing from the one of gripping the wheel or the handlebar descried above, is the one of leaning with both hands onto the rim of the steering wheel, pressing both palms hard against it. This is an instinctive and most rapid reaction aimed at protecting the thorax region from impacting the wheel in case of brisk deceleration of the vehicle for any reason, e.g. because of an obstacle—a pedestrian—seen suddenly in front of the vehicle. The hands in this case press hard, with strong force corresponding to an acceleration of 2 to 3 G, against the upper surface of the steering wheel rim oriented towards the driver, and this force inventively can be made use of for activating a pneumatic or hydraulic sensor located in the upper portion of the rim of the steering wheel. Thus, thanks to the hydraulic or pneumatic sensor, the possibility of obtaining a signal proportional to the driver's perception of danger, i.e. a signal constituting a noticeable progress over all sensors operating with a simple electrical switch, which can only give off on/off signals that do not account for the speed of the driver's reaction nor for the force of his reaction or, respectively, for his “degree of panic”.

A second aspect revealed in practical application of the solution according to the EP-1 21 691 1A2 is that the whole extent of the steering control (i.e. the whole circumference of the steering wheel in the case of an automobile, or the whole length of the handlebar, in the case of vehicle with a handlebar) is to be used as an activating zone for the hydraulic or pneumatic sensor. Expressed in other words: Practical use has shown that, while driving a vehicle, the driver tends to shift his hand—or both his hands, if he applies them both—along the whole surface of the rim of the steering wheel or, respectively, along the whole length of the handlebar. Thus it never can be known precisely, where the hand or the hands of the driver contact or hold the steering control. Of course there are favoured zones, such as the two sides to the right or to the left hand side, or the upper and the lower zone of the steering wheel rim. But it is impossible to foresee precisely at which point the driver, in an emergency or panicking situation, will grip the wheel or the handlebar. For this reason the solution shown in the EP-121691 1A2 cannot entirely satisfy the conditions for effectiveness required for a safety device such as the one considered here.

It is the objective of the present invention to eliminate the disadvantages cited above still inherent in the state of the art, represented in particular by the EP12 '16911A2, and to offer the market a solution, which ensures maximum effectiveness in all panic situations of the driver, independently of his driving habits, in particular of his way of holding the steering wheel while driving.

This objective is met thanks to a steering control presenting the characteristics according to the characterising portion of the claim 1.

Owing to the application of at least one hydraulic or pneumatic sensor extending essentially over the whole zone of the steering control that may be gripped by at least one hand of the driver of the vehicle, the steering control being the steering wheel of an automobile or the handlebar of a motorcycle, best assurance is obtained that the sensor can be activated securely, whatever the situation is. For obtaining this result at least one sensor is provided, which is a hydraulic or a pneumatic sensor—being able to transmit an increase in pressure at any of its points to a receiving device provided with it—consisting of a tube of elastic material immersed in expanded foam plastic material, the final elasticity of which (i.e. after hardening of the material) preferably is lower than the elasticity of the material forming the tube. Owing to this characteristic the pressure exerted by the hands (or by one hand only) onto the plastic foam material completely surrounding the tube of the sensor (forming the rim of the steering wheel or the cylindrical body of the handlebar) is immediately transmitted to the tube, which in turn transmits it to the fluid contained in the tube, in such a manner that the pressure increases inside the tube. The signal receiver in the form of a pressure gauge, the pressure value being determined with an analogue electric measuring device, and the signal emitted immediately can be processed in many different modes (start of the braking action, switching on of warning lights, etc.) which, however, are apt to reduce the dangers generated by the panic situation causing the driver's brisk reaction. It is to be stressed that the pressure gauge can be calibrated in such a manner that it emits a signal only if he pressure increase in the sensor-tube exceeds a predetermined value, in order to avoid undesired reactions of the system due to mere inattentiveness of the driver.

The depending claims 2 through 12 concern preferred embodiments of the present invention, which will be described and discussed in more detail with reference to the following description illustrated in corresponding Figures. The Figures show in:

FIG. 1 an inventive steering control in the form of a steering wheel of an automobile shown schematically in a view from below;

FIG. 2 a cross-section of the rim of the steering wheel along the line I-I in the FIG. 1;

FIG. 3 the tube-shaped sensor located inside the inventive steering control;

FIG. 4 an alternative arrangement of the tube-shaped sensor in a steering wheel of an automobile for realising the present invention;

FIG. 5 a section along a zone of the steering wheel of an automobile, in which the tube-shaped sensor is placed in the outer portion (as shown in the FIG. 4), but with additional support elements against which the tube rests;

FIG. 6 an alternative variant of the inventive steering control as shown in the FIGS. 1 through 5, but equipped with two tube-shaped sensors, one of which is located in the outer rim portion of the wheel, and the other one of which is located in upper portion of the rim of the wheel;

FIG. 7 a design detail of the solution according to the FIG. 6 showing the manner in which the two sensor tubes merge into one pressure gauge;

FIG. 8 an alternative design example of a steering wheel in which the polyurethane is rigid and the sensor is placed into a peripheral slot milled into the rim.

In the FIG. 1 a steering wheel 1 of an automobile is shown schematically, seen from below (i.e. from its lower portion). The steering wheel of conventional type, applied in the automobiles circulating today, comprises a rim 2 and a number of spokes 3 (often two or three spokes) connecting the rim 2 with the steering column 4. The specific layout of the steering wheel 1 (namely the diameter of the rim, the number of spokes, the specific shape of the steering column head 4) plays a minor role within the frame of the invention and thus is not discussed in more detail here. It just is to be noted that modern steering wheels of automobiles as a rule contain a support structure (skeleton) made from light metal alloys (magnesium in particular) for lending the steering wheel the strength required and the indispensable safety characteristics. A skeleton 5 of such type presents an e.g. M-shaped profile (see the FIG. 2, in which the cross-section of the rim of the steering wheel 1 along the line I-I of the FIG. I is shown) and of course comprises the spokes 3 and the steering column head 4 (not visible in the figures). The skeleton 5 normally is embedded at least partially, especially in its rim portion, in a plastic foam material of predetermined elasticity, in such a manner that its touch is pleasant and assures good grip. The elasticity of the foam plastic material, plainly visible in the cross-sections in the FIGS. 2 and 4 and indicated with the reference number 6, plays a particular role within the scope of the present invention, which is to be described later on. In the FIG. 4 it can be seen furthermore that the plastic foam material 6 as a rule is enclosed in a cover 7 of soft leather or half-leather in order to further improve the surface properties of the steering wheel. This does not ply any significant role in practical use, as far as the present invention is concerned.

Of importance is just the fact—actually already present and known in the steering wheels and in the handlebars according to the state of the art—that the material of which the plastic foam material is made from (preferentially made e.g. from expanded polyurethane or from a material presenting characteristics similar to polyurethane) is elastic and can undergo local elastic deformation under the influence of the pressure exerted by a hand that grips the wheel, or exerted just by a finger pressed onto the surface. This local elastic deformation is made use of patent-wise for obtaining the desired safety effect. Mentioning elastic deformation, it is to be defined here that this expression can refer to the local deviation of the form of the gripping zone as well as to the reduction in its volume: both cases can be made use of in practical application, depending on whether the wheel rim is pressed by a hand that grips the wheel, or whether it is pressed just locally. From the viewpoint of the present invention the two cases are entirely equivalent as they generate the same effect, as will be explained later on.

The present invention is characterised in that the hydraulic or pneumatic sensor 8 extends essentially over the whole zone of the steering control, e.g. of the steering wheel 1, which can be gripped by at least one hand of the driver (not shown). In the case of the specific item shown in the FIGS. 1 through 5 the gripping zone extends essentially over the whole rim 2 of the steering wheel 1, as actually the whole rim 2 can be gripped or be held by the driver. In the case of the handlebar of a motorcycle (not shown) the gripping zone extends over the full length of the handlebar. At whatever point the driver grips or holds the steering control, the safety system thus will function as the hydraulic or pneumatic sensor extends over the full expanse of the gripping zone. In this arrangement the characteristics of a fluid contained in a tube can be made use of: the pressure applied at whatever point of the tube immediately is propagated throughout the tube. The present invention provides that the sensor 8 be a tube 9 (see the FIG. 3 especially) of elastic material, filled with a fluid 10 and embedded in foamed plastic material 6 (see the FIGS. 2 and 4), the final elasticity of the expanded foam material (where the term “final” refers to the elasticity after completion of the hardening phase of the expanded foam material) being equal or lower than the elasticity of the material of which the tube 9 consists. This definition is stated because of the requirement that the tube 9 of the sensor 8 does not oppose any useless resistance against compression from the outside, in order not to render the combination of the foam material 6/tube 9 needlessly inert against pressure loads. The tube 9 thus is not to oppose pressures, but is to transmit them to the fluid 10 that fills the tube and reacts to any, and even smallest, deforming loads acting onto the foam material that surrounds the tube 9.

In the FIG. 1 it can be seen in which manner the tube 9 forming the sensor S surrounds practically the whole circumference of the steering wheel 1, being placed in the rim in suitable manner, to be described later on, and re-entering towards the steering column 4 via one of the spokes 3, forming a portion curved 90° with respect to the circumference of the rim 2.

According to a first preferred realisation of the present invention, shown in the FIG. 1 as well as in the FIG. 3, the tube 9 is sealed tight using a sealing clip 11 at one end, whereas its other end is connected to a pressure gauge with an electrical analogue measuring value transmitter 12, which transmits its signal via suitable circuits 13 to a signal processing unit that processes the signal conveniently, e.g. the on-board computer. Obviously there are other solutions than clips for sealing a tube 9, and also connecting to a tube under pressure a pressure gauge furnishing an analogue electric signal, correspond to the state of the art. All such solutions thus are applicable within the frame of the present invention.

Practical experience has permitted to establish that application of a hydraulic sensor 8 is preferable, which consists of a tube 9 as described above, filled with a liquid, which preferentially presents minimum thermal dilatation within the temperature range from −40° C. to +100° C. The advantage of this solution is self-evident. The liquid is essentially incompressible and thus reacts faster and with higher precision than a pneumatic sensor filled with a compressible gas. The smallest possible thermal dilatation within the range of temperatures cited is desirable, as this permits elimination of possible deviations in pressure occurring in the steering control exposed to outside conditions in the environment. The steering wheel if an automobile must remain functional notwithstanding considerable temperature excursions, such as found between polar and equatorial regions, also if modification of the calibration of the pressure gauge 12 in function of the average temperature at which the automobile is used can be considered.

According to another preferred form of realisation of the present invention, shown in the FIG. 2 presenting a cross-section of the steering control along the line I-I indicated in the FIG. 1, the steering control can be the steering wheel 1 of an automobile (as shown in the FIG. 1) and the hydraulic or pneumatic sensor 8 can be arranged along the whole circumference of the steering wheel 1 (as shown in the FIG. 1) in its lower portion, at a distance d ranging from 1 to 6 mm from the surface of the steering wheel rim 1, thus under the magnesium skeleton 5, is apt to activate the sensor when pressed by a finger or by the hands. Most drivers instinctively grip the wheel 1 laterally with the palm of the hand, in such a manner that the fingers, except the thumb, are placed on the lower portion of the steering wheel rim. If the hand tightens, the fingers tend to press the wheel rim, puffing a load onto the material, the filling foam material is made of, upwards from below, and thus the tube 9 of the sensor 8, arranged in that location, is compressed. This location of the sensor 8 thus is privileged for realising the present invention.

According to another preferred variant of realisation of the present invention, indicated in the FIG. 4 showing a cross-section of the steering control similar to the one shown in the FIG. 2, the steering control is represented by a steering wheel 1 of an automobile, and the hydraulic or pneumatic sensor 8 is arranged on the outer side along the whole circumference of the steering wheel rim at a distance D ranging from 1 to 6 mm from the surface of the steering wheel 1. It is to be noted that in the form of realisation according to the FIG. 4 the surface of the steering wheel is covered with a thin layer 13 of leather or half-leather, which is provided, on one hand, to protect the expanded plastic foam material 6, and on the other hand to improve the grip on the wheel 1 for the driver. The distance D thus is measured from the outer surface of the cover layer 13.

The advantage of this form of realisation is seen in that the sensor 8 is located in a lateral position of the wheel 1, where it can be strained easily as the driver grips the wheel and tends to pull back his arms.

In the FIG. 4 it also can be seen in which manner the elastic tube 9 of the sensor 8 via its guide element rests directly against one of the vertical protrusions or arms of the support structure 5. This represents an advantageous solution facilitating manufacture of the steering wheel, which does not play any particular role within the scope of the present invention, however.

On the other hand an advantageous solution of an inventive steering wheel I is obtained, if it contains, as shown in the FIGS. 2, 4 and 5, a support structure or skeleton 5 embedded entirely or partially in the expanded plastic foam material 6, where the structure 5 comprises a steering column head, spokes and a wheel rim (not shown in their details, but corresponding to the steering column head 4, the spokes 3 and the wheel rim 2 of the foam material forming the steering wheel 1) made from light metal alloys, preferentially from magnesium, and where the tube 9 of the sensor 8 rests against at least one point of the support structure 5. This solution is shown in the FIG. 5, in which support blocks 15 of suitable shape (shown schematically in the FIG. 5) are arranged on the support structure 5, e.g. using normal distancing clips, against which the tube 9 of the sensor 8 rests. This solution proves suitable for facilitating the foam expanding process in the manufacture of the steering wheel 1, i.e. the processing step during which the foam material is brought into the mould at relatively high pressure (e.g. at 5 to 6 kg/cm2), which could cause shifting of the tube 9 with respect to the support structure 5. The support blocks 15 thus serve as a fixation of the position of the tube 9 during this manufacturing step of the steering wheel, ensuring the correct position of the tube 9. Obviously the two positioning solutions shown in the FIGS. 2 and 4 can be applied together, if two sensors 8 in form of a tube 9 are provided or if just one sensor 8 in form of a tube 9 is provided, which alternatively is placed along the circumference of the steering wheel 1 in the positions indicated in the FIG. 2 and in the FIG. 4, or can change from one position to the other and back according to the zone of the steering wheel concerned.

According to a preferred form of realisation of the present invention it furthermore is provided that the tube 9, or 17 respectively, presents an outside diameter ranging from 2 to 6 mm, and is made from a plastic material such as silicone, EVA (vinyl-ethylene acetate) or a similar material.

Another preferred form of the present invention is represented finally in the FIGS. 6 and 7, which show the solution in which the sensor 16 is located in the upper portion of the steering wheel 1, i.e. on the side facing the driver, along its whole circumference. As described before, this solution permits most rapid protective reaction, in particular if the driver, as an unexpected obstacle emerges in front of the vehicle, such as a pedestrian crossing the road without watching the traffic, using both hands pushes hard against the steering wheel in order to protect himself against a seemingly unavoidable collision. This actually is the first instinctive reaction. The sensor 16 thus reacts immediately and activates the predetermined protective measures. In the FIG. 16 it is shown in which manner two sensors 8 and 16 can jointly be placed in the rim of the steering wheel, the first sensor e.g. in the outer portion and the second one in the upper portion of the steering wheel. This layout permits realisation of a double chance of reaction in one arrangement, and thus permits doubling the degree of safety.

In the FIG. 7 it is shown in which manner the two sensors 8 and 16 merge into one single tube in order to activate one single pressure gauge 12. The advantage of this arrangement is obvious. The tube 17 is located in the rim of the wheel at a distance f ranging from 1 to 6 mm from the surface of the steering wheel. Another preferred form of realisation provides that, in the preferred case in which a hydraulic sensor is chosen, the filling liquid is glycol, silicon or a similar liquid. This liquid is filled into the tube 9, 17, preferentially under vacuum during the filling process, in such a manner that that absolutely no bubbles remain inside the tube 9, 17. This, however, is a manufacturing problem known to any specialist in the field and is not relevant within the scope of the present invention.

Concerning finally the plastic material forming the outer shape of the steering wheel 1, manufacturing experience has shown that tat among the many possibilities available the one providing the application of an expanded polyurethane foam material presents an ideal solution with respect to the elastic characteristics as well as to the ease of manufacture and to cost efficiency. This material thus represents a preferred choice, not excluding the use of other foam materials that can be injected under pressure, or pressed, into a mould, however.

Everything described here thus far also is valid for steering wheels the foaming process of which determines also the final surface of the polyurethane material with mock leather effects. It has been noted that the manufacture of steering wheels to be covered consecutively with genuine leather (which operation is called “saddlery” among specialists) preferentially must be effected using a more rigid polyurethane material, which causes major difficulties in the process of inserting the tubes and of the sensor or the sensors, inventively required, in the foam material insertion into the mould.

In this case the steering wheel (see the FIG. 8) preferably is foamed without previous insertion of the tube or the tubes and later is machined by milling, in order to create the recess or slot 18, info which the inventive tube or the tubes of the sensor or the sensors are placed subsequently. For this purpose a slot 18 preferentially is machined into the circumference of the steering wheel at the preferred location (above, under, outer side, etc.) of essentially semicircular cross-section as shown in the FIG. 8, into which the tube 17 of the sensor fits perfectly. The tube 17 must protrude from the polyurethane surface over just 6 to 8% of its total diameter. This solution is applied only where the relative hardness of the polyurethane precludes sufficient elastic local deformation of the tube.

The advantages of the steering control according to the present invention, especially its application in its preferred form of a steering wheel 1 of an automobile can be summarised as follows:

- 1) Absolute effectiveness and reliability as the danger sensor functions in whatever position the hands of the driver contact the wheel, taking into account also the fact that scientific tests have proven that the hands react faster than the feet, and that thus the safety systems monitoring the hands of the driver, like the one according to the present invention, prove more efficient.
- 2) The sensor 8, 16 can be provided, if the pressure gauge 12 is calibrated correspondingly, in such a manner that it reacts only and exclusively in case of panic of the driver, i.e. of real emergency situations, thus avoiding unnecessary and potentially dangerous reactions of the system due to awkward operation by the driver.
- 3) The inventive steering control is easily manufactured at low cost and thus can be incorporated in all types of vehicles, automobiles or motorcycles, including commercial vehicles, road safety thus being much enhanced.

Number	Date	Country	Kind
01275/04	Jul 2004	CH	national
00256/05	Feb 2005	CH	national

Steering control for self-propelled vehicles

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