CH631122A5 - VEHICLE SUSPENSION. - Google Patents

Description

The invention relates to a vehicle suspension, for example for railway vehicles and vehicles with rubber tires.

The suspension of vehicles with rubber tires described in United States patent No. 3984125 and the suspensions 55 of railway vehicles described in United States patents Nos. 3961582 and 3961584 include several springs, in the form elastic bodies of substantially circular cross-section, as main elastic elements for load bearing and friction damping. These known suspensions 60 incorporating shock absorbing devices are designed to provide the desired elastic and damping characteristics for a defined load. Consequently, when vehicles fitted with such suspensions are not loaded, their travel is often rough and, when they are overloaded with respect to the defined load, the 65 springs harden and the damping effect may become insufficient. In railway cars, these rough strokes or excessive compression of the springs can lead to derailment or excessive wear.

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The invention aims to provide a vehicle suspension which eliminates these problems, in particular which adjusts to the load and which, other than known suspensions, can provide, for example during the compression of the spring, greater damping than that which intervenes during the expansion of the spring, so as to minimize the shocks transmitted to the vehicle and reduce wear.

To this end, the suspension according to the invention is characterized in that it comprises a device with a mobile load arm articulated to the body of the vehicle and now an axle relative to this body, an elastic device carried by this arm device. load and receiving the load of the body, the first and second compression elements operatively associated with the body and the load arm device for applying compressive loads to the elastic device, friction damping elements ensuring a damped movement at friction of the load arm device with respect to the vehicle body, these friction damping elements comprising a friction damping surface connected to the body and a friction damping element carried by the load arm device and in sliding contact with the friction damping surface, and mounting means connecting the damping elements and the second compression element to the di load arm device in support relation with the elastic device, so as to be movable with the load arm device.

Such a vehicle suspension is, for a given load and under given frequency conditions, lighter than conventional suspensions using log springs with circular section or conventional elastomer compression springs. It has a frequency lower than that which could be obtained, until now, by means of springs in the form of elastic bodies with circular section, or by means of conventional elastomer compression springs. It also has a frequency which is substantially constant for a predetermined load range. It can also produce an autoguiding action when entering the curve. It is particularly suitable for a railroad bogie with autoguiding, construction with two axles, with a single axle, or with a single axle and articulated.

According to one embodiment of the invention, the elastic device can be constituted by a spring in the form of an elastic body of elliptical cross section. A control unit,

mounted in a load transmission position to the spring and to the friction damper, performs the simultaneous application of forces to this spring and to this damper. This control element rests on a support surface on which the load is applied, and it is designed and positioned with respect to this surface so that a first component of a support force, resulting from the load applied to the support surface, either transmitted to the spring in the form of a force vector in a fixed position, exerting only one pressure, and a second component of this support force is applied simultaneously to the following friction damper a perpendicular force vector corresponding to a normal force.

In most practical applications, the upper surface of the spring in the form of an elastic body, supporting the load, can bear against a suitable surface for applying suitable load, carried by the vehicle. The control element and the support surface are aligned vertically below the spring so as to support the load, the control element being interposed between the spring and the support surface, although other forms of alignment can be used. The support surface is presented by a load arm which provides a load connection between the vehicle body and a drive element, by a member mounted on an axle of the vehicle or by any other suitable means, depending on the alignment of the log spring, control element and shock absorber.

In another embodiment, the control element has a tapered profile and has upper and lower contact surfaces which diverge along the force vector associated with the normal force component applied by this element to the damper . The support surface is inclined and parallel to the lower contact surface. The upper contact surface of the control element is parallel to and in contact with one of the load surfaces of the spring, while the lower contact surface slides against the surface of the support. Consequently, any lateral movement or movement of the support surface under the effect of the support forces results in a simple sliding with respect to the lower contact surface and, therefore, is not transmitted to the upper surface. of contact. The control element is also connected to the friction damper so as to maintain a substantially fixed position relative to this damper during the application of a force. The upper contact surface of the control element therefore remains in static contact with the spring during the application of a force.

According to one embodiment, the friction damper has two parallel friction surfaces, movable with each other, roughly perpendicular to the vector along which the normal force component, indicated above, is applied by the control element. A first friction surface is connected to and moves with the control element so that, in response to the application of the normal force component, it is applied against the other friction surface to frictionally produce a variable damping force.

In its application to a tandem suspension for vehicles with rubber tires, for example, the suspension may comprise two pairs of independent load arms, with intermediate pivot. Each pair of arms is associated with a single spring in the form of an elastic body, and with a single friction damper of the types described above. In such an application, and in other applications to vehicles with rubber tires, the suspension distributes the load while reducing the rebounds of the wheels considered separately by around 50%; it exhibits desirable dynamic qualities by limiting oscillations by means of variable damping proportional to the load; it reduces the forces due to shocks by achieving a damping which varies with the load; it increases rolling resistance; it has an extended and safe service life by the use of a spring in the form of an elastic body; it has a tendency to autoguiding when entering the curve, which reduces the wear of the tires by friction when the cornering speeds exceed the equilibrium speeds, and also reduces the drag of the rolling resistance; it provides good stability during acceleration and braking, without skipping the wheels; it significantly reduces unsprung masses; and it has a substantially constant frequency in most of the load ranges encountered in practice.

As for railway applications, the suspension has a large number of advantages. The use of independent load arms, as well as springs in the form of elastic bodies and friction dampers associated with these arms, gives a self-guiding property to the bogie equipped with the suspension according to the invention and which, at the Unlike the four-wheel or articulated bogies of the prior art, for example, maintains a low angle of attack of the curved track and tends to follow the curvature of the rails at speeds greater than the equilibrium speed. This bogie retains its autoguiding properties on a curve on the left or on other curves that can cause a rolling movement of the vehicle, or on switches or curves of service tracks. The suspension also absorbs and absorbs the forces due to impacts at points very close to the rails and, consequently, it has very desirable elasticity and damping characteristics for the structure of the vehicle, for the load of this vehicle and its ancillary equipment such as the wheelhouse and coupling devices.

In the two applications to vehicles with rubber tires and to railway vehicles, the spring in the form of an elastic body with an elliptical cross section of the suspension is preferred, since it gives the suspension lower frequencies, under conditions

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of load given, for a weight substantially lower than that which could be obtained in the prior art by the use of springs in the form of elastic bodies with circular section or conventional compression springs made of elastomer. This spring also gives the suspension substantially constant frequencies within given load ranges. In most practical applications of suspensions to vehicles with rubber tires and to rail vehicles, this spring is theoretically unbreakable, does not allow hooking and has a non-linear coefficient of elasticity. Consequently, it has a very effective, although very flexible, response to the load which can vary over a wide range between low loads and large loads or even shocks. Consequently, the destructive vertical accelerations are reduced or appreciably minimized, while the rolling qualities are improved, even on road or on bad track and at high speeds. It is obviously possible to use instead of said springs with elliptical cross section springs in the form of elastic bodies having other profiles, or else other types of springs.

The variable-action friction damper adjusts automatically to compensate for wear during the service life of its wearing parts, without affecting its operation as is the case with shock absorbers and shock absorbers hydraulic, or conventional friction dampers whose effectiveness drops in a manner directly proportional to the wear of the friction surfaces.

The invention will be described in more detail with reference to the accompanying drawings by way of examples and in which:

fig. 1 is a partial elevation of a railway vehicle with fixed axles equipped with the suspension according to the invention, the latter being shown under load;

fig. 1A is a partial perspective view of the representation of FIG. 1;

fig. 2 is a partial elevation, roughly analogous to that of FIG. 1, showing the suspension under a light load;

fig. 3 is a diagram showing the conditions of force transmission present in the suspension shown in FIG. 1;

fig. 4 is a plan view of an articulated bogie of a railway vehicle, equipped with the suspension shown in FIG. 1;

fig. 5 is a partial section along line 5-5 of FIG. 4;

fig. 6 is a plan view of a two-axle bogie fitted with the suspension shown in FIG. 1;

fig. 7 is a partial section along line 7-7 of FIG, 6;

fig. 8 is a partial plan view of a trolley with only one axle for a vehicle with a rubber tire, equipped with the suspension shown in FIG. 1;

fig. 9 is an elevation of the carriage shown in FIG. 8;

fig. 10 is a partial plan view of a vehicle with rubber tires with rear axle with two axles, equipped with the suspension shown in FIG. 1;

fig. 11 is a partial section along line 9-9 of FIG. 10; fig. 12 is a partial section along line 12-12 of FIG. 11; fig. 13 is a perspective view of a spring in the form of an elastic body with an elliptical section, forming part of the suspension; lafig.l4estunevueen plan of the spring shown in fig. 13;

fig. 15 is an elevation of the spring shown in FIG. 13;

fig. 16 is an end view of the spring shown in FIG. 13; fig. 17 is a graph indicating the load as a function of the bending of the spring shown in FIG. 13;

fig. 18 is a schematic end view showing conditions for applying a load, under the effect of centrifugal force, to the suspension shown in FIGS. 10 to 12 when the vehicle follows a curve;

fig. 19 is a diagram showing the self-guiding characteristic of the suspension shown in FIGS. 10 to 12 under the load conditions indicated in fig. 18;

fig. 20 is a graph showing the static frequency as a function of the load for two prior art two-axle axle suspensions and for the suspension shown in FIGS. 10 to 12;

fig. 21 is a graph showing the acceleration as a function of time of a suspension of the prior art and the suspension shown in FIGS. 10 to 12;

fig. 22 is a graph indicating the displacement as a function of time of a suspension of the prior art and of the suspension shown in FIGS. 10 to 12;

fig. 23 is a view along line 23-23 of FIG. 4;

fig. 24 is a section along line 24-24 of FIG. 7;

fig. 25 is a plan view of a variant of the bogie shown in FIG. 4, two of these bogies being connected to each other;

fig. 26 is a partial section along line 26-26 of FIG. 25; fig. 27 is a partial section along line 27-27 of FIG. 26; fig. 28 is an elevation, with partial section, substantially similar to that of FIG. 7, showing a variant of the bogie shown in FIG. 7;

fig. 29 is a partial elevation, substantially similar to that of FIG. 11, showing a variant of the vehicle with rubber tires shown in FIG. 11, and fig. 30 is an elevation, substantially similar to that of FIG. 11, showing another variant of the vehicle with rubber tires shown in FIG. 11.

Figs. 1 to 3 represent the vehicle suspension according to the invention which comprises a spring 10 constituted by an elastic body in the form of a log, a friction damper 12, and a control element 14 disposed below the spring 10 and connected by a pivot 15 to the friction damper. A pivoting load arm 16 supports the control element and the spring. This control element 14 applies certain forces, coming from a common load exerted by the arm 16, to the spring 10 and to the damper and, at the same time, it controls or adjusts this spring or this damper.

In the example shown in fig. 1 and 2, the suspension is mounted on a railway vehicle with fixed axles. In this example, the inner end of the arm 16 is connected to the body 20 of the vehicle by a pivot 18 with a plastic ring with a low coefficient of friction. The outer end of the arm 16 supports one end of an axle 22 by means of an intermediate support member 23 (FIG. 2) and a guard element 25 disposed at the bottom. An elastomer suspension pad 24 (fig. 1) is interposed between the intermediate element 23 and the arm 16 and absorbs the forces transmitted between these elements. An independent and identical load arm, the associated spring, the friction damper and the control element equip the vehicle body 20 at the other end of the axle 22 (not shown) and ensure the transmission of loads between the body and the axle.

As shown in fig. 1 and 2, the control element 14 has a tapered profile and has upper and lower contact surfaces 26 and 28 which diverge substantially towards the damper 12, as shown in FIGS. 1 and 2. The upper contact surface 26 is opposite the lower load surface presented by the resort 10 and it bears against this lower surface in order to ensure the transmission of the loads with it. However, it cannot move relative to this lower surface when the suspension is loaded, as described below. The lower contact surface 28 bears against an inclined and underlying support surface 30 relative to which it can move. This surface 30 is formed by the outer end of the load arm. The upper contact surface 26 is parallel and opposite to an upper load application surface 32 which, in the example described, is formed by the vehicle body and bears correspondingly against the upper bearing surface of the spring 10 The latter is compressed transversely between these surfaces 26 and 32 under the application of the loads, as described below.

In the example described, the friction damper has two parallel friction surfaces 34 and 38 which can move relative to each other. The surface 34 is formed by a conventional friction pad, carried by a friction sole 36 which is articulated, by an axis 15, with the relatively wide end of the control element 14, as shown in FIGS. 1.1A and 2. Surface 38 is

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consisting of an element which projects downwards from the body of the vehicle. The surfaces 34 and 38 are arranged relative to the control element 14 so as to remain in contact with one another in the absence of load (fig. 2). When they are pressed against each other under the application of a normal force by the control element 14, during the movements of the arm 16 relative to the body 20, the surfaces 34 and 38 produce a friction damping force, of variable amplitude. In the example described, the surface 38 is inclined relative to the stroke of the arm 16, so that the friction damping force produced during the downward movement of the load arm exceeds that produced during its upward movement, as described in more detail below.

The control element 14 simultaneously applies perpendicular components of a force, exerted by the load arm, to the spring 10 and to the shock absorber, as shown diagrammatically in FIG. 3. As shown in this last figure, a bearing force is applied by the load arm 16 to the control element 14, via the surfaces 28 and 30, along an inclined vector 40 which is perpendicular to the contact surface 28. The control element 14 therefore exerts a first component of the force of the load arm, via the surface 26, on the spring 10, this component being oriented along vector 42 and therefore applied to the lower load surface of the spring, essentially and only in the form of compression. The control element 14 simultaneously applies a second component of the force of the load arm, via the pivot 15, to the damper 12, according to a perpendicular vector 44. This latter force is in the form of 'a normal force compressing the surfaces 34 and 38 against each other.

As is more particularly apparent from FIGS. 1 and 1 A, the friction sole 36 is connected to the control element 14 in the form of a wedge by the axis 15 which allows it to pivot relative to the control element 14 in a vertical plane. This allows the friction surface 34 of the friction sole 36 to remain in contact with the friction surface 38 when the load arm 16 pivots towards the body of the vehicle or moves away from it. The friction surface 34 of the friction sole 36 is kept in contact with the friction surface 38, and applies against it a vertical force which is a component of the load acting on the suspension, because, as explained here, the lower surface 28 of the control element 14 is slidably mounted in the channel formed by the surface 30 of the load arm 16.

The surfaces 34 and 38 are advantageously arranged so that the distance over which they must move together, to produce by friction a damping force having the desired amplitude, is sufficiently small (preferably negligible) for the element to control 14 does not tend, when applying a force, to move laterally with respect to the spring 10 over a distance modifying the conditions of static contact between this control element and the spring. As the surface 34 or surface 38 wears out, it is obvious that the control element tends to approach. However, this movement of the control element is sufficiently gradual that, in most practical cases, it has no effect on the conditions of contact with the spring 10. A particularly important characteristic of the suspension described is therefore that the friction damper automatically adjusts for wear during its entire service life.

So that the suspension shown in fig. 1 retains these load conditions, the surface 30 can move parallel to the surface 28 during the pivoting of the load arm. To this end, a layer 46 of material with a low coefficient of friction can be interposed between the surface 30 and the surface 28. Consequently,

when the load arm pivots relative to the body, the position of the control element 14 relative to the spring, in a plane coinciding with the surface 26, is not modified, and this surface and the lower load surface , which is opposite to it and which is presented by the spring, therefore remain in static contact with each other.

In the example described, the friction surface 38 is inclined relative to the stroke of the load arm so that the friction damping force obtained during a downward movement of the load arm exceeds the force obtained during the upward movement of this arm. In particular, the surface 38 forms an acute angle with the arc of a circle traversed by the load arm and indicated by the double arrow in FIG. 1. Consequently, when the load arm 16 rises from the position shown in FIG. 2 to that shown in FIG. 1, the force exerted according to the vector 44 indicated in FIG. 3 appears to be a normal force of decreasing amplitude, since the surface 38 is inclined so as to move away from the upward stroke of the arm 16 and of the control element 14. Conversely, when the load arm descends from the position shown in fig. 1 to that shown in fig. 2, the surface 38 approaches the path followed by this arm, and consequently by the control element, and the normal force thus obtained therefore tends to increase.

The suspension is shown in fig. 1 and 2 under two load conditions, respectively. In fig. 1, the suspension is shown as it appears at full load, while in FIG. 2 it is shown under a light load. Figs. 1 and 2 show the spring 10 under a bending corresponding to a value between about 40 and 45%, and to a value between 15 and 20% of its empty height, respectively, and, in both cases, the side walls unsolicited spring have a substantially circular profile. Under the application of shocks, the spring shown in figs. 1 and 2 flexes over 55 to 60% of its height in the free state, although it can withstand even greater deflections without deterioration.

As appears from a comparison of FIGS. 1 and 2, the areas of the respective load surfaces of the spring 10 tend to increase when the amplitude of the pressure exerted by the load increases. This increase in the area of the load surfaces is obtained by the application by rolling of certain parts of the lateral surfaces and of the end surfaces of the spring on the opposite and respective surfaces 26 and 32, as shown. Consequently, the form factor of the spring increases in proportion to the progressive increase in the load. The expression “form factor” used in the present specification designates the ratio of the area of the bearing surfaces of the spring to the area of the surfaces without load, which can bend freely under the effect of a load. When the form factor increases, it is necessary to increase the compression loads to obtain a given bending. In other words, the spring becomes stiffer, or its resistance to compression increases in proportion to the form factor. It is therefore possible, by giving the spring 10 a cross-sectional profile allowing a form factor varying with the load, to obtain for this spring a bending curve in non-linear load or with variable slope, of the type shown. in fig. 17. The latter represents the bending curve as a function of the load for a spring having, for example, a large axis of 23 cm, a small axis of 16.5 cm and a length of 16.5 cm. It is particularly important to note that a spring of elliptical section makes it possible to obtain a bending curve of this type, as well as very desirable suspension frequencies and a reduced weight, as described in more detail below.

The surfaces 26 and 32 are kept parallel to each other,

as indicated previously, and respectively in contact with the upper and lower surfaces of the spring. In the example shown in figs. 1 and 2, the surfaces 26 and 32 are arranged so that, when they are subjected to opposite vertical forces exerted respectively by the vehicle body and the load arm, the spring is pressed and compressed transversely between them, without turning , according to force vectors occupying fixed positions and substantially perpendicular to the longitudinal axis of the body and coinciding with the major axis of the spring. It is obvious that the direction of an applied load is not axial, that is to say that the spring is not

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stressed and therefore does not behave like a column loaded at the end, and that this spring, being subjected only to compression, does not behave like a spring working in shear or like a spring working both in compression and in shear. Consequently, these contact surfaces can rotate, move or slide freely with respect to each other during the application of a load so that, when the spring is compressed (as shown and described), the torsional forces , the shear forces or the moments of force tending to twist or rotate it around its longitudinal axis, or parallel to this axis, io are suppressed or minimized, which is accompanied by elimination or corresponding minimization of destructive shear stresses and wear of the surface of the elastomer constituting the spring.

The spring is shown in more detail in FIGS. 12 to 16. It is made up of a solid elastomer body, preferably made of natural rubber. Its upper and lower load surfaces (bearing the references 48 and 50 respectively) are convex and preferably curved around the longitudinal axis of the body. Likewise, the ends 52 and 54 are convex and join the surfaces 20

upper and lower load, as well as the sides of the body, by rounded angles, as shown in figs. 14 and 15. A single centering pin 56 projects upwards from the upper load surface, and two lower positioning pins 58 projects from the lower load surface. These nipples have a suitable external shape 25 allowing them to be aligned with suitable recesses made in surfaces 26 and 32 (shown in FIGS. 1 and 2) and introduced into these recesses, in order to prevent or substantially reduce the tendency of the spring to move or rotate relative to these surfaces while it is under compression, and also to facilitate positioning of the spring during assembly. The rounded shape of the load surfaces allows the adjacent side walls to gradually roll against the bearing surfaces under the effect of a compression load, which reduces the stresses generated in the elastomer under the effect of a load and therefore increasing the life that can be obtained. The rounded load surfaces also maintain the stability of the spring under the effect of increased flexions and, therefore, allow the use of springs with increased ellipse ratios (ratio of the major axis to the minor axis).

The ellipse ratio and the length chosen for the spring shown in the figs. 13 to 16 depend on the frequency of the suspension, beyond the range of loads in service, on the weight and the lifespan desired for this suspension. In general, the suspension frequency obtained under a given load is inversely proportional to the ellipse ratio used. By using an elastomer having a hardness, measured with a durometer, high, a high suspension frequency is obtained; however, hysteresis effects tend to be pronounced for elastomers of great hardness and, therefore, a spring made of such an elastomer has a greater tendency to heat up after repeated charging cycles. In the case of elastomers of great hardness, the life of the spring therefore tends to decrease in a manner proportional to this hardness. By lengthening the spring, it is possible to increase the load capacity, but the natural frequency of the spring increases appreciably due to its increased resistance to the coming into contact by rolling of the extreme surfaces without load of the spring with the surfaces of support.

In most practical applications, the spring preferably has an ellipse ratio of less than about 2.5: 2, and more preferably between about 1.1: 1 and 2.2: 1. Its length must be at least equal to the length of its minor axis and its hardness must be between approximately 40 and 70 °, according to the International Rubber Hardness Degrees (IRHD) standards. Six natural rubber springs were produced with a hardness of 50 ° and having the following characteristics, given by way of non-limiting examples:

Report

Length

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Charge*

Ellipse weight

(cm)

(cycles / min)

(daN)

(kg)

1.38: 1

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952

0.94

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170.61

819

0.79

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10

168.51

748

0.67

2.0: 1

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0.51

* With a bending of 40%.

As indicated by the previous examples, the ellipse ratio also has a significant effect on the weight obtained for the spring, the springs having high ellipse ratios being appreciably lighter than those which have smaller ellipse ratios. . Conversely, when the ellipse ratio approaches 1: 1, which corresponds to a circular section, the weight of the spring obtained for a given frequency and for given load conditions increases appreciably. 55

Figs. 4,5 and 23 show the suspension described in its application to an articulated bogie for a railway vehicle. The suspension shown in figs. 4,5 and 23 is substantially similar to that shown in figs. 1 and 2; it comprises two identical devices 59 each consisting of an independent load arm, so of a spring 10 and an associated friction damper, except that each load arm acts between the corresponding spar of the bogie and the axle. The elements of the suspension shown in figs. 4, 5 and 23, identical to those of the embodiment described above, bear the same reference numbers, to which the letter A is added.

The articulated bogie shown comprises two parallel beams 60 which are connected to each other, at the corresponding ends,

by a transverse spacer 61 which, as shown in FIG. 23, comprises a lowered median section, substantially Y, when considered in lateral profile. The bogie shown supports a load crossmember 62 carrying a central beam 63 associated with a suitable vehicle body. Lateral supports 64, carried respectively by the two longitudinal members, support the vertical load exerted by the ends of the cross-member 62. An elastic ring 65 of elastomer, carried by the cross-member 62, and a centering pivot 67 of the bogie, carried by spacers 69, maintain the crosspiece 62 under the effect of horizontal loads and the articulation between the vehicle body and the bogie. The elements 69 transmit the lateral forces and the braking forces between the spacer 61 and the pivot 67. In the case of an articulated railway vehicle, a coupling element 71 is carried by the spacer 61, proximity of its lowered center, so as to connect the bogie shown to a neighboring bogie (not shown) associated with a second vehicle body (not shown), in order to prevent the chassis of the bogies from oscillating with respect to each other when crossing a curved track. A head end 73 carries a drawbar or coupling bar 55, articulated on a pivot axis 57 (FIGS. 4 and 5). This drawbar 55 acts between the neighboring ends of the body

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shown and the second box (not shown) in order to transmit the buffering and traction forces, that is to say the pushing and pulling forces appearing between the boxes. When coupled, the two bogies behave like a two-axle, self-steering bogie, the latter characteristic being described in more detail below. U.S. Patent No. 3,961,582 describes a lateral support and an elastic ring suitable for the vehicle shown.

In the example shown, the pivot axis of the bogie, surrounded by the elastic ring 65, is offset longitudinally with respect to the axis 57 of the drawbar and, consequently, the bogies tend to move longitudinally l '' one in relation to the other, by a toggle or articulation effect, when the vehicle is entering a curve. In the example described, the coupling element 71 must allow such displacement of the bogies and, if desired, it can also allow relative rotary movement of the bogies around a longitudinal axis, as described in the patent for United States of America No. 3961582 supra. In other applications where the pivot axis of the drawbar is in vertical alignment with the pivot axis of the bogie, the coupling element 71 must be rigid in the longitudinal direction, but it must allow rotation relative bogies if desired.

Figs. 25 to 27 show a variant of the bogie of FIG. 4. The elements of this embodiment identical to those of the embodiment described above bear the same numerical references, followed by the letters AA. The bogie shown in figs. 25 to 27 is substantially similar to that of FIG. 4, except that the longitudinal members 60AA and the elements 61 AA and 69 A A have different shapes. In addition, the bogie has a pivoting lock 73 and an element 74 fixed to the central beam 63AA, in order to prevent the bogies from oscillating when the coupling element 71 AA is not fixed. As shown in fig. 26, the bolt 73 is placed on the path followed by one of the telescopic members constituting the coupling element 71 AA, so as to be kept in the withdrawn position away from the element 74. A spring (not shown) tends to return the latch 73 to the position of engagement with the element 74 when the coupling element 71 AA is not fixed.

Figs. 6,7 and 24 represent the application of the suspension to a two-axle bogie. The suspension shown in figs. 6,7 and 24 is substantially similar to that shown in figs. 1 and 2. It comprises four suspension devices 66 each comprising an independent load arm, a spring in the form of an elastic body and an associated friction damper, except that each load arm works between a beam of the bogie and an axle. The elements of the suspension shown in figs. 6,7 and 24, identical to those described above, have the same reference numerals, to which the letter B is added.

The bogie with two axles shown comprises two parallel beams 75, having substantially the shape of a T when viewed in elevation (as shown in FIG. 7), these beams being substantially similar to the beams 60AA of the bogies shown in the fig. 26. The outer ends of each spar are of reduced thickness and relate respectively to springs arranged below them, while the intermediate part of each spar is of increased thickness. Two load arms 16B are mounted so as to be able to pivot on this intermediate part by means of two neighboring pivots 16B, as shown in FIG. 7. A cross member 77, for example having a lowered median section, of substantially V-shaped profile (as shown in FIG. 24), is bolted and connected to the side members, near their intermediate part. This cross member 77 is sufficiently flexible, in torsion, to allow the side members 75 to be able to pivot around the longitudinal axis of the cross member 77, in their respective vertical planes. Lateral supports 81, carried by the two beams, are intended to support the vertical loads exerted by the ends of a load cross member 83. The horizontal holding of the cross member 83 and the articulation between the vehicle body and the bogie are provided by an elastic ring 85 made of elastomer carried by the cross member 77 and by a central pivot 87 bolted to the cross member 83, as shown in FIG. 24. The bolted connections between the longitudinal members and the cross member 77, and between the pivot 87 and the load cross member 83, are preferably made by means of withdrawal or self-locking nuts having a high resistance to vibrations. U.S. Patent No. 3,961,584 describes a lateral support and an elastic ring that can be used in the bogie shown.

As shown in fig. 28, the load arms of the two-axle bogie shown in FIG. 7 can be mounted on a pivot 93. The elements of the embodiment shown in FIG. 28, identical to those described above, have the same reference numerals, to which the letters BB are added. The pivot 93 can be fixed to the beam 75BB or it can be mounted in a movable manner relative to this beam, in an oblong hole,

described in more detail below with reference to FIG. 30, is shown at 174 in this fig. 30.

Figs. 8 and 9 show the application of the suspension to a vehicle with rubber tires, with a single axle. The suspension shown in figs. 8 and 9 is substantially similar to the embodiments shown and described above and, therefore, its elements identical to the elements described above have the same reference numerals, to which the letter C is added. However, the suspension shown in figs. 8 and 9 differs from the previous embodiments in that it comprises a separate element 71 having the inclined support surface 30C.

In the embodiment shown by way of example in FIGS. 8 and 9, the vehicle is constituted by a trailer carriage which comprises a coupling element 72 intended to be connected to a conventional trailer coupling, and two divergent arms 74 and 76 which end in parallel sections 78 and 80 arranged above the axle 82 of the vehicle. A fifth wheel 83 is mounted on the sections 78 and 80 of the arms, as shown in FIG. 9. The axle 82 carries the element 71 and it is supported, with respect to the arms 74 and 76, by an articulated parallelogram consisting of two upper and coplanar control rods 84 and 86 which converge with pivots by means of which they are connected to the sections 78 and 80 towards pivots close to the middle of the axle 82, and by two lower and coplanar control rods 88 and 90, mounted in the same manner as the upper rods, but parallel to each other and below sections 78 and 80 of the arms, as shown in FIGS. 8 and 9.

Figs. 10 and 11 show the application of the suspension to a vehicle with twin axles and rubber tires. This suspension is substantially similar to the variants shown in FIGS. 1 to 9, except that each spring 10 works between opposite and mobile parts of two load arms mounted on a common pivot. Two sets of load arms (only one set being shown) support the ends of the two axles 94 and 96. A spring in the form of an elastic body constitutes the only elastic load support element for each set of arms. A single set of arms, as well as the spring, the shock absorber and the other associated suspension elements, are shown and described, the other set of arms and its associated suspension elements obviously being identical.

As shown in fig. 10 and 11, the suspension comprises a front or exterior load arm 98 and a rear or interior load arm 100. These arms pivot, at a point situated between their ends, on a central and common ring 102 which carries a saddle 104 fixed to the chassis 106 of the vehicle from which it projects downwards. The upper parts of the saddle are connected, respectively by traction thrust rods 108, to supports 110 in a cup, associated with the axles 94 and 96 and projecting upwards of these, in a conventional manner. The outer ends of the load arms have rubber rings 112 and 114 connected by brackets 116 and 118 to the axles.

The suspension shown in figs. 10 and 11 comprises a spring 120 of elliptical section, substantially similar to the springs 10 shown and described above. The upper load surface

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of the spring bears against the surface formed by a part 122 of the arm 100, extending the latter and arranged in height, as shown. The lower load surface of the spring rests on an opposite surface 123, presented by a movable damper console 124. The lower surface of this console is inclined and can slide against a corresponding inclined surface, presented by the arm 98, and it can move relative to the latter when the spring is compressed, so as to exhibit a behavior substantially similar to that of the control element 14 described above with reference to FIGS. 1 and 2. The relatively thick end of the shock absorber console supports a shock pad 126 consisting of a suitable friction sole. This stud bears against a surface of a tubular damper element 128, open at its ends and carried by the free end of the arm part 122, as shown in FIG. 9. One side of the damping element has a substantially flat surface 130 (FIG. 12), opposite the stud 126 against which it can slide when the arms 98 and 100 pivot relative to one another. The other side of the damping element has a substantially V-shaped cross section (fig. 10), so as to include two surfaces 132 and 134 inclined with respect to each other and oriented, respectively, facing two studs additional 136 and 138 of damping carried by the arm 100, as shown in FIG. 12. The shock absorber console 124 tends to cause the pads 126, 136 and 138 to rub against the surfaces 130, 132 and 134, respectively, when it is subjected to a load exerted by the arms 98 and 100, as is the case of the control element 14 shown in FIGS. 1 and 2.

Fig. 29 shows a variant of the suspension shown in FIG. 11. The element common to these two embodiments has the same reference numerals, to which the letter D is added in FIG. 29. The suspension shown in fig. 29 comprises two load arms 140 and 142, the outer ends of which are connected by brackets 116D and 118D to the axles 94D and 96D, respectively. The inner ends of the arms 140 and 142 are articulated at 144 and 146 on the corresponding ends of a pendulum 148. This pendulum is articulated at 151, between the pivots of the arms, with a sole 104D. Springs 150 and 152 are mounted on control elements 154 and 156, themselves supported by the arms 140 and 142, respectively, as is the case of the suspension shown in FIG. 1. The control elements 154 and 156 also tend to rub the soles 158 and 160 against the friction surfaces 162 and 164. A substantially similar suspension, consisting of two load arms and a pendulum, can be used with the bogie shown in FIGS. 6 and 7.

Fig. 30 shows a second variant of the suspension shown in FIG. 11. The elements common to these two embodiments (as well as to that shown in FIG. 29) bear the same numerical references, to which the letters DD are added in FIG. 30. A single load arm 170 is connected, at its ends, by brackets 116DD and 118DD to axles 94DD and 96DD, and it carries springs 150DD and 152DD. An axis 172,

being able to move in a vertical oblong hole 174 presented in the saddle 104DD, supports the arm 170 at an intermediate point. Consequently, this arm can slide vertically along the oblong hole 174, relative to the saddle 104DD, in order to distribute the load of the chassis 176.

As shown in fig. 18 and 19, the suspensions shown in figs. 4 to 7.10 to 12 and 23 to 30 provide automatic steering in the curves due to the independent movements of the load arms under the effect of centrifugal force, as described below. Figs. 18 and 19 show the self-guiding characteristic of the two-axle suspension shown in FIGS. 10 to 12; the suspension forms shown in figs. 4 to 7 and in figs. 23 to 29 have substantially the same characteristics in curves. The single axle suspensions shown in figs. 1,2, 8 and 9 have a self-guiding characteristic when they are arranged at opposite ends of a vehicle.

As shown in fig. 18 and 19, when a vehicle with pneumatic tires fitted with the suspension shown in FIGS. 10 to 12, negotiates a turn as it moves in the direction indicated by the arrow in fig. 19, the centrifugal force acts relative to the center of gravity so as to tend to tilt outward the upper part of the body, as indicated in FIG. 18, the outer side being indicated in EXT and the inner side in INT in FIG. 19. Consequently, the load exerted on the suspension elements associated with the exterior wheels tends to increase, while the load applied to the suspension elements of the interior wheels tends to decrease. The load arms located outside therefore tend to further distance the outer ends of the axles from each other, while, at the same time, the load arms located inside tend to bring one of the other the inner ends of these axles, as shown in fig. 19. Consequently, the axles tend to align themselves on radii R of the curve until the conditions showing the centrifugal force and indicated above disappear, that is to say until the vehicle resumes straight ahead.

As shown in fig. 20, the suspension has a substantially constant frequency over the entire extent of a predetermined range of loads. Fig. 20 indicates the static frequency of the springs, obtained under typical load conditions, with the suspension for two axles shown in FIGS. 10 to 12, although the other embodiments of the suspension may have substantially similar frequency curves. Fig. 20 also shows the frequency curves characterizing two suspensions of the prior art for tandem axles, these curves of the prior art being indicated by the letters AA. As it appears, the frequency curve characterizing the suspension according to the invention indicates a substantially constant frequency within the load limits indicated, this load being indicated on the abscissa and the frequency on the ordinate, in cycles per minute.

Figs. 21 and 22 show other operating characteristics of the suspension for tandem axles shown in FIGS. 10 to 12, these characteristics also applying to the other embodiments of the suspension described. Figs. 21 and 22 also show the corresponding characteristics presented by a suspension with dancing crosspiece of the prior art, equipped with leaf springs, the prior art being indicated by the letters AA.

As shown in fig. 21 which indicates the time on the abscissa and the accelerations on the ordinate, the suspension according to the invention makes it possible to reduce the rebounds of the tires (2 instead of 3), and to reduce the amplitude of the accelerations which immediately follow in relation to the suspension of the prior art, following an impact at 80 km / h against a bump 5 cm high and 15 cm long. As shown in fig. 22, the suspension according to the invention also has a lower bending than that of a previous suspension, indicated in AA, and faster damping, under the same impact conditions.

Alternatively, the suspension shown in FIG. 11 can be designed to use two springs in the form of elastic bodies and two friction dampers, by means of two crossed arms each having a lower part similar in shape to that of the lower part of the arm 98, so as to be able to carry a spring and a control element on one side of the pivot of the arm, the latter also having an upper part similar in shape to that of the part 122 in order to allow the mounting of a damper and to bias a spring on the other side of the pivot .

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Claims (16)

631122 1. Vehicle suspension, characterized in that it comprises a device with a movable load arm articulated to the body of the vehicle and now an axle relative to this body, an elastic device carried by this device with a load arm and receiving the load of the body, of the first and second compression elements operatively associated with the body and of the load arm device for applying compressive loads to the elastic device, friction damping elements ensuring a friction damped movement of the arm device load relative to the vehicle body, these friction damping elements comprising a friction damping surface connected to the body and a friction damping element carried by the device with load arms and in sliding contact with the friction damping surface, and mounting means connecting the damping elements and the second compression element to the arm device of ch arge in support relationship with the elastic device, so as to be movable with the load arm device. 2. Suspension according to claim 1, characterized in that the friction damping surface is inclined relative to the arcuate stroke of the movement of the load arm device, to adjust the damping force during the upward movement of this device and the compressive force exerted on the elastic device. 2 3. Suspension according to claim 1, characterized in that the means for mounting the friction damping elements comprises a tapered control element slidingly connected to the load arm device, so that a load exerted by the arm device load is applied as a first component to the elastic device as a compressive force, and as a second component for actuating the friction damping elements. 4. Suspension according to one of claims 1 or 2, characterized in that the means for mounting the friction damping elements comprises means for minimizing the relative horizontal displacement of the elastic device between the first and the second compression element, the elastic device being compressed without it rotating. 5. Suspension according to claim 2, characterized in that the means for mounting the friction damping elements comprises a tapered control element slidingly connected to the load arm device, so that a load exerted by the arm device load is applied as a first component to the elastic device as a compressive force, and as a second component to the friction damping elements as a force perpendicular to the friction damping surface. 6. Suspension according to claim 4, characterized in that the elastic device comprises an elastomer spring positioned to receive compressive loads. 7. Suspension according to claim 1, characterized in that the vehicle body comprises two lateral beams and in that the load arm device comprises four load arms, two of which are mounted so as to be able to pivot on one of the longitudinal members in order to support the first corresponding ends of two axles, the other two load arms pivoting on the other longitudinal member in order to support the corresponding second ends of the two axles, in that the elastic device comprises four elastic elements carried by the four arms load, so as to produce an elastic suspension independent of the four load arms relative to the side members. 8. Suspension according to claim 7, characterized in that the load arms are mounted on the side members so as to independently increase the distance separating the ends of the two axles associated with each member, in response to an increase in the vertical load of the respective member . 9. Suspension according to claim 7, characterized in that the side members are connected by a flexible cross-member in torsion, to allow the side members to be able to pivot around the longitudinal axis of this cross member. 10. Suspension according to claim 1, characterized in that the load arm device comprises two load arms articulated on the body to support the respective ends of an axle, in that the elastic device comprises two elastic elements intended for providing an elastic suspension independent of the two load arms relative to the vehicle body, and in that the vehicle body includes an alignment device to keep the body in longitudinal alignment with the body of a neighboring vehicle suspension. io 11. Suspension according to claim 10, characterized in that the load arms are mounted to the body so as to independently increase the distance separating each end of the axle and the body of a neighboring vehicle suspension, in response to a increase in the vertical load applied to the respective associated load arm 15 by the body. 12. Suspension according to claim 1, characterized in that the load arm device comprises two load arms articulated with each other between their ends and connected respectively to the corresponding ends of two axles mounted in tandem, these arms load comprising opposite sections between which the elastic device is arranged to act simultaneously on the two load arms. 13. Suspension according to claim 1, characterized in that the load arm device comprises an axle support and a 25 articulated parallelogram pivotally mounted between the body and the axle support. 14. Suspension according to claim 1, characterized in that the load arm device comprises a pendulum articulated to the body between its ends and two articulated load arms, close to 30 one of their respective ends, at opposite ends of the pendulum near opposite ends thereof, and, near the other of their ends, at one of the respective ends of two axles mounted in tandem. 15. Suspension according to claim 1, characterized in that the load arm device comprises a load arm so connected to be able to slide at the body between its ends and articulated, near its ends, at the ends of two axles mounted in tandem. 16. Suspension according to one of claims 12,14 or 15, 40 characterized by means connecting the load arms to the body so that the distance between the ends of the two axles mounted in tandem increases in response to an increase in the vertical load transmitted to the load arm by the body.