SK150197A3 - Semi-rigid vehicle axle - Google Patents

Abstract

The vehicle semi-rigid steel rear axle has a tubular shaped median zone constituting the cross member (3). The section of the median zone is such that it confers to this zone a bending resistance and a capability of torsional deformation. Each of the ends (10,11) of the cross member is extended by two open tube sections (12-15) which form between them at the start of the cross member a dihedral angle (D) less than 180 degrees. One of the two sections (12,14) of each end, the connecting section, provides the fixing to the bodywork. The other two sections (13,15) of each end, the arm section, provide the fixing for the axle heads carrying the wheels.

Description

The invention relates to a semi-rigid tubular axle used mainly to form the rear axle portion of an automobile and to a method of manufacturing such an axle. It is an axle comprising a central cross member, the ends of which are formed on each side of the open tube parts, making it possible to secure, directly or indirectly, a connection to the vehicle structure, in particular the bodywork and the wheel fitting. Thus, such an axle makes it possible to secure the connection to the vehicle structure, to steer the wheels and to provide a function of anti-tilt (oscillation). The axle to which the invention relates is of tubular construction.

BACKGROUND OF THE INVENTION

The semi-rigid rear axles of the vehicles providing the above functions are known, and these axles are generally formed of at least five cross-sections, two arms connected to each end of the cross-beam, for example by welding, the assembly having a U-shape and connecting pieces. , for example, welded to the crossmember and shoulders to ensure attachment to the body. In order for the semi-rigid axle to perform the functions expected of it, it is necessary to provide a crossbar having sufficient flexural rigidity coupled with sufficient elastic torsional deformation capability.

In fact, the arms mounted on both ends of the cross-member must be able to rotate relative to each other about the axis of the cross-member by its elastic twisting, the wheel axes remaining virtually parallel to each other during this rotation. In order to achieve this result, it is necessary that each arm exhibit at the same time a high flexural and torsional stiffness. These strengths, combined with the flexural strength of the crossmember, are especially needed to resist the torque and bending moments generated by the tire's grip on the road.

When forming the crossmember and the control arms from three separate parts, it is possible to provide each of the parts with optimum parameters, which are then assembled by well known means such as welding. Thus obtained

816 / B axles have the disadvantage that they are relatively expensive because they require the use of a number of components that need to be manufactured separately and then joined together in a sequence of work operations. In addition, these axles are relatively heavy, since at the level of the connecting areas the cross-sections have to be reinforced.

A semi-rigid axle is also known, from French Patent No. 2 590 847, lightened with respect to the axles described above, having a partly monoblock construction not requiring shoulder mounting on the crossbeam and having, in addition, mechanical properties which enable it to perform the wheel guidance and function tilt protection.

This U-shaped axle has a partially monoblock tubular structure formed from one lengthwise piece of tube. It comprises a central region which forms a cross-member and which is profiled so as to have at least one double-wall flange. At each end of the crossmember, the area beyond the profiled region is substantially perpendicular, elongated by an arm at the end of which is secured the axle head on which the wheel is mounted.

The attachment of this axle to the vehicle structure (body) is provided by articulated coupling means, such as bearing pins, fixed to the axle along an axis parallel to the longitudinal axis of the cross-member and mounted rotatably in resilient bearings attached to the rigid structure of the body. This function of attachment to the bodywork therefore requires the use of additional components which have to be manufactured separately and then connected to the crossbar.

The invention has sought to create a semi-rigid axle of the type described, having an integral tubular structure and requiring little or no such assembly processes and which would allow three functions at the same time to steer the wheels, resist tilting and assure attachment to the vehicle structure. ensure easy implementation.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides a semi-rigid axle for an automobile, comprising a tubular profiled central region forming a crossbeam, wherein each of the crossbeam ends is elongated by two portions of an open tube clamping at an angle of less than 180 ° therebetween.

816 / B, the attachment portion, secures the means for attachment to the vehicle structure, in particular the body, and the other of each end portion, the arm portion, secures the axle heads carrying the wheels, the assembly having a tubular structure.

By two portions of an open tube is meant two V-shaped profiles from the tube at the above-mentioned angle, the transverse profile of which corresponds essentially to the part of the open tube profile, which is not necessarily circular and whose longitudinal profile is straight or curved and therefore not necessarily planar. wherein both arms of the letter V are not necessarily in the same plane, and wherein both profiles extend from said tube. The thickness of the tubular axle thus defined may be substantially constant over the entire length of the part or may have deflections to better accommodate the stresses to which it must resist in its various parts at the current minimum weight. This axle is preferably symmetrical with respect to the cross-sectional plane passing through the center of the cross-member.

This axle is preferably made of steel. It may be formed of three tube lengths, one of which serves as a profiled crossbeam and the other serving to form an extension comprising each two open tube portions as described above, each end of the crossbeam being connected, for example, by welding to the end of one of the extensions. Preferably and very preferably the axle will be monoblock, i. which is very favorable in terms of mechanical strength and ease of manufacture of the axle according to the invention.

Where it is necessary to provide a sufficient thickness stiffness different from the cross-member thickness and / or to reinforce the axle without unnecessarily increasing the weight, it is possible to select a tube or tubes having optimized diameters and thicknesses. Alternatively, it is also possible on each side to connect the two open tube parts with the reinforcing means to maintain their spacing against the stresses to which the axle is subjected. This reinforcement means is formed, for example, by a part whose profile is shaped to fit all or both parts of the open tube which it joins or parts thereof. It may be mounted in whole or in part on the profile or in the profile of the two open tube parts it connects. Preferably, each reinforcing means is generally triangular in shape, which is not necessarily planar and occupies all or part of the area between the two open tube portions. Other types of reinforcing element may be used, for example, a tie rod connecting the two parts or

816 / B a metal strip welded along both parts to close them and to give them a box construction.

The cross-sectional profile preferably comprises at least one flange with two walls, perpendicular to its axis, both walls being parallel or non-parallel. Concurrently, it is understood that both walls may have any shape and be substantially equidistant from one another, of course, the shape is not necessarily planar. For example, the profile is U, L, T, V, X, Y, Z, or H, and is not limiting. In the profiled central tubular region, the two walls of the at least one flange are preferably in contact with each other or at least very close to each other, for example 0.1 to 1.5 mm.

The longitudinal and transverse profiles and the length of each of the open tube parts are designed to resist in-service stresses and allow the attachment of attaching means to the respective parts of the vehicle (bodywork) and the axle hub for the wheels. Preferably, the cross-section is U-shaped. It may also have a semicircular shape, an oval shape, a semi-rectangular shape or any suitable shape according to the needs of the embodiment. The longitudinal profile of each part is not necessarily planar and for each group of two parts the position and orientation of one part can be very variable with respect to the other, both profiles not necessarily in the same plane.

Preferably, the coupling means for connection to the vehicle structure is articulated. For example, it may be formed by a bearing that is welded to the end of the attached part and which is adapted to receive a flexible connection.

Preferably, the axle head on which the wheel will be mounted is mounted on the arm member and is provided with an element intended to fit the end of the spring, the other end of which is connected to the vehicle structure, to transmit the vehicle load to the wheels. These springs are, as is known, helical springs. This further increases the compactness, integrity and simplicity of the axle according to the invention. This element can also be formed as an independent part, fastened to the arm part of the axle.

The axle may be supplemented by other known elements, for example dampers or torsion bars.

The invention further relates to a method for producing a semi-rigid tubular axle, in its monoblock form according to the invention, in which a single pipe length is used

816 / B of circular or non-circular cross-section, of constant or non-constant thickness, to be subjected to the following processes in which:

(a) create cuts at each end of the pipe, the length of the cut being calculated according to the length of the longer of the two parts;

(b) the two parts of at least one end are stretched apart and shaped in one or more steps on the forming tools to obtain an angle at their exit from the cross-member of less than 180 °;

c) expanding and shaping the parts of the other end in the same way,

d) if necessary, the parts are length-adjusted according to the geometrical parameters of the patch, this step possibly being carried out after process e),

e) and the central region of the tube deforms to give it a profile shape, wherein process e) may alternatively also be performed before process a) or between processes a) and b) or between processes b) and c) or between processes c) and d).

Preferably, processes b) and c) are performed simultaneously. Preferably a rotary tube and preferably a steel tube is used.

The central region of the tube may be deformed in process e), giving it the shape of a profile having at least one flange with two walls. Preferably, the profile thus formed comprises at least one flange with two walls that are parallel or non-parallel. This deformation of the central region is preferably performed so that the two walls of the at least one flange come into contact with each other or are close to each other, as described above. In particular, the central region may be deformed such that a U, L, T, V, X, Y, Z, or H-shaped cross-section is obtained.

In the case where reinforcing means are required between the open tube parts, the method comprises at least one process of fitting these reinforcements with known means such as welding.

Preferably, the ends of the tube in the cutting area are shaped prior to making the cutting in process a) by providing them with an oval or rectangular profile or any suitable shape corresponding to the profile of the parts or necessary for fastening the open tube parts with means for attachment to the body. , axle heads for wheels and any reinforcing means.

816 / B

Advantageously, notches are formed at regular intervals at the cutting edges to prevent metal cracks when forming open tube parts in process b) or c) in cases where the deformation angle is significant.

If desired, heat treatment of the entire axle or also of certain areas thereof, such as a crossbeam, can be carried out during the forming operations or on the finished axle.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in more detail in the following by way of example with reference to the accompanying drawings, in which: FIG. 1 is a plan view of an axle according to the invention, FIG. 2 shows a section through the axle forming tube of FIG. 1 according to the method of the invention, FIG. 3 shows a section along line A in FIG. 1, FIG. 4 is a section along line B in FIG. 1, FIG. 5 is a diagram showing a method according to the invention, and FIG. 6 is a cross-sectional view of the expanded end of the tube prior to cutting.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 shows schematically a tubular monoblock semi-rigid axle 1 according to the invention. This axle is formed of a single length piece of circular cross-section tube, the profile 2 of which is enlarged relative to the scale of FIG. 1 is shown in FIG. 2. This pipe has a constant thickness e from one end to the other.

The axle comprises in the central part a cross-member 3 formed by deformation of the central part of the tube. It is given the shape of a profile 32 with straight edges, section A of which is shown in FIG. 3. It will be appreciated that the profile comprises two U-shaped flanges 4, 5 around the X-X axis. Each flange has a double wall 6, 7 or 8, 9 obtained by shaping the starting tube. The two walls 6, 7 or 8, 9 are mounted opposite each other, thereby increasing the twisting capability. Such a profile has a high flexural strength, somewhat lower than the starting tube of circular cross-section and has a resilient torsion strength much smaller than that of the starting tube. Besides that

The 816 / B permits considerable deformation of one end of the cross-member relative to its other end in torsion without leaving the elastic section.

Obviously, at each of the ends 10, 11 of its profiled portion 32, the crossbeam 3 is extended by two portions of the open tube 12, 13 for the ends 10 and 14, 15 for the end 11 forming an angle D of about 120 ° at the exit of the crossbeam. The sections 12, 13, 14, 15 have a U-shaped cross-section as indicated by the profiled part 14 in section B in FIG. 4. The two parts 12, 13 or 14, 15 of each end 10, 11 of the crossbeam 3 are connected to each other by a corresponding reinforcement 16, 17.

The reinforcement 16 welded to the sections 12, 13 and the reinforcement 17 welded to the parts 14, 15 have a U-profile adapted to that of the parts 12, 13, 14, 15, as shown in FIG. 4, and a triangular profile engaging and closing the area between the open tube portions 12, 13, 14, 15, which engages and closes the area between the open tube portions 12, 13, 14, 15, as shown in FIG. These stiffeners 16, 17 are mounted on corresponding parts 12, 13 or 14,15 and then welded to them as shown in FIG. 4 for the reinforcement 17 and the parts 14, joined together by welds 33.

At the end of each of the open tube parts 12, 14 disposed on the X-X axis and thus forming the attachment portions, a welded bearing 18, 19 is provided to fit a resilient joint (not shown) to form a hinged connection to the vehicle body or frame in a known manner.

At the end of each of the two parts 13 and 15, located below the X-X axis forming the arm parts, a welded axle head 20, 21 is provided with a member 22, 23 in a known manner to fit the end of a helical spring (not shown), the other end of which is connected to the bodywork for transmitting the vehicle load to the wheels.

Notches 29 are formed on the open tube portions 13, 14, 15 to eliminate the formation of cracks in the metal when forming the tube portions.

It will be appreciated that such an axle allows rotation of each of the tube assemblies 12, 13 or 14, 15 and the corresponding stiffeners 16, 17 relative to each other, given the ability to flex the torsion beam 3, generating a return torque that tends to return. both together. The maximum reciprocating angle of one arm to the other depends on the mechanical properties of the steel forming the cross-member 3, their profile and dimensions.

816 / B

In a known manner, the dampers (not shown) allow the rotating bends to be controlled about the X-X axis of the component assemblies and stiffeners. If necessary, other known elements, such as a torsion bar, can be added to the axle equipment.

The cross-member 3 may have different profiles to obtain good elastic torsion deformation associated with increased flexural strength, for example, L, T, V, X, H, Y or Z shapes, with or without the flange walls being pressed against themselves. Thus, the U-shaped profile can be formed with or without touching the walls 6, 7.

Likewise, the profile of the parts 12, 13, 14, 15 may have different shapes to accommodate the technical constraints of the axle, for example a semicircular, oval or more complex shape. The length of the connecting portions 12, 14 is not necessarily the same as the length of the leg portions 13, 15.

The stiffeners 16, 17 may be formed in various ways to ensure their function of keeping the tubes 12, 13 open tube and 14, 15 apart from each other due to the stresses exerted on the axle, for example in the form of a tie rod joining the two pieces or metal strip welded along both parts for their and to provide them with a box construction.

Finally, the attachment means 18, 19 and the axle heads 20, 21 on which the wheels will be mounted can be formed in various ways known in the vehicles, the fastening to the connecting parts or arms being carried out by welding or any known fastening means.

Fig. 5 illustrates a schematic method of manufacturing a semi-rigid axle according to the invention of FIG. 1. Starting from a piece of round tube, the profile 2 of which is shown in FIG. 2. Each end 27 of the starting tube is expanded by known conventional means, such as a press, to obtain the profile 31 of FIG. 6 in the length required to form future parts 12, 13, 14, 15. The profile 31 shows the tube before the incision is made.

The tube is then held by the dies 24, 25, not shown, and cuts 28 are formed at each end 27 on the long side of the rectangle 31 of FIG. 6, by means of conventional known cutting means, on the length required to form future open tube parts 12,13,14,15.

Along the cut 28, notches 29 are formed to prevent the formation of cracks in the metal during the subsequent formation of tube parts. The parts 12, 13, 14, 15 are then formed simultaneously

816 / B by stretching using one spreader mandrel 30 on each side, which is moved in one step towards the forming dies 24, 25 by a device (not shown) firmly connected to a press (not shown). In FIG. 5 shows the situation before stretching to the right of the Y-Y axis and the situation after stretching to the left of the Y-Y axis.

The parts 12, 13, 14, 15 are then brought to the required length depending on the axle properties, and the reinforcements 16, 17 of FIG. 1, which have been manufactured by any known means and are fitted in a conventional manner by welding according to the scheme of FIG. 4, which shows in cross-section the parts 14 and the reinforcement 17 connected by welds 33.

The next step consists in deforming the central region of the tube in a known manner to give it a U shape and the desired orientation according to FIG. 3 to form the crossbeam 3. The bearings 18, 19 and axle heads 20, 21 of FIG. First

Various variants of the method are possible, for example as set forth below, without limitation. The ends 27 of the starting tube need not be shaped and may remain circular. Alternatively, for example, they may have other shapes, such as oval, depending on the constraints imposed on the axle. The notches 29 are formed only for high amplitude deformations where there is a real risk of cracking. Reinforcements 16, 17 of a different concept, for example tie rods 12, 13 and 14, 15 or a metal strip welded along these pieces, may also be used to provide the box structure. The cross-member 3 can also be L, V, T, X, H, Y or Z, with or without flange walls. The articulated carriers 18, 19 and axle heads 20, 21 may be designed in different ways depending on the vehicle type and may be fixed in various ways on the parts 12, 13, 14, 15.

By way of example, an axle according to the invention has been formed from a circular cross-section tube with an outer diameter of 90 mm and a thickness e 2.15 mm of steel according to DIN St 52 having a reference elastic limit E of 0.2% of 400 MPa. these parameters:

a cross-member 3 with a length of 900 mm profiled in a U-shape according to FIG. 3

816 / B parts 12, 13, 14, 15 with an extended length of 450 mm, the U-shaped cross-section according to FIG. 4 and capable of withstanding a torque deflection of 300 Nm with a cross-sectional angular deformation of 20 °.

The axle of the invention may be made of materials other than steel, the choice of material being based on the normal design of the axle designer. In order to improve the mechanical properties, it is possible, in the case of a steel axle construction, to carry out, after shaping the axle according to the invention, a heat treatment of the entire axle or its local heat treatment. The remedy and the method of its manufacture can be subjected to a number of possible variations without departing from the spirit and scope of the invention.

Claims (22)

Semi-rigid axle for an automobile, comprising a tubular profiled central region forming a cross-member (3), characterized in that each end (10, 11) of the cross-member (3) being elongated by two open tube parts (12, 13, 14, 15), forming an angle (D) of less than 180 ° between them at the exit of the cross-member (3), one of the parts (12, 14) of each and the other of the end members (13, 15), the arm portion, securing the axle heads supporting the wheels, the assembly having a tubular structure. Axle according to claim 1, characterized in that the profile of the central region is such that it confers bending strength and elastic deformation in torsion to this region. Axle according to claim 1 or 2, characterized in that it is monoblock, i.e. formed of a single length piece of tube. Axle according to claim 1 or 2, characterized in that it is made of three tube lengths, each end of the crossbeam being connected to two parts of one tube length. Axle according to at least one of Claims 1 to 4, characterized in that the central tubular region forming the cross-member has a profile with at least one flange with two walls. Axle according to at least one of Claims 1 to 5, characterized in that the cross-member (3) is preferably U, L, T, V, X, Y, Z or H in cross-section. Axle according to claim 5 or 6, characterized in that in the profiled central region (3) the two walls (6, 7) of the at least one flange are in contact with each other. 30,816 / B Axle according to at least one of Claims 1 to 7, characterized in that the parts (12, 13, 14, 15) have a U-shaped cross-section or a semicircular shape, an oval shape or a semi-rectangular shape. Axle according to at least one of Claims 1 to 8, characterized in that the open tube parts (12, 13) and (14, 15) of each end are connected by a reinforcing means (16, 17). Axle according to claim 9, characterized in that the discharge means (16, 17) is formed by a part whose profile is shaped to fit all or both of the parts (12, 13,14,15) to be joined or parts thereof. Axle according to claim 9 or 10, characterized in that each reinforcing means (16, 17) is fully or partially mounted on the profile or in the profile of the two parts (12, 13, 14, 15) which it connects. Axle according to at least one of Claims 9 to 11, characterized in that each reinforcing means (16, 17) has a generally triangular shape which is not necessarily planar and occupies all or part of the area between the two parts (12, 13, 14). , 15), which connects. Axle according to at least one of Claims 1 to 12, characterized in that the connection (18, 19) to the vehicle structure is provided by a hinge connection means, preferably mounted on the connection part and preferably at its end. Axle according to at least one of Claims 1 to 13, characterized in that the axle head (20, 21) on which the wheel will be mounted is fixed to the arm part and is provided with an element intended to fit the end of the helical spring, the other end is attached to the vehicle structure. Axle according to at least one of Claims 1 to 14, characterized in that it is made of steel. 30,816 / B 16. A method of manufacturing a semi-rigid tubular axle comprising a central profiled cross-sectional region elongated at each end by two portions of an open tube by a connecting portion and an arm portion clamping at an angle of less than 180 ° therebetween. that a single lengthwise piece of tube is used, which is subjected to the following processes in which: (a) create cuts at each end of the pipe, the length of the cut being calculated according to the length of the longer of the two parts; (b) the two parts of at least one end are stretched apart and shaped in one or more steps on the forming tools to obtain an angle at their exit from the cross-member of less than 180 °; c) expanding and shaping the parts of the other end in the same way, d) if necessary, the parts are length-adjusted according to the geometric parameters of the axle, this step being carried out after process e), if necessary; e) and the central region of the tube deforms to give it a profile shape, wherein process e) may alternatively also be performed before process a) or between processes a) and b) or between processes b) and c) or between processes c) and d). Method according to claim 16, characterized in that processes b) and c) are carried out simultaneously. Method according to claim 16 or 17, characterized in that the central region of the pipe is deformed in process e), and is given a profile shape having at least one flange with two walls. Method according to at least one of Claims 16 to 18, characterized in that the central region of the pipe is deformed in process e) so as to obtain a U-shaped, L, T, V, X, Y, Z-shaped cross-section. or H. Method according to at least one of Claims 16 to 19, characterized in that notches are formed at the edges of the incisions before the stretching process b). 30,816 / B Method according to at least one of claims 16 to 20, characterized in that it comprises at least one process of fitting the reinforcement elements between the open tube parts of each end. Use of axles according to at least one of claims 1 to 15 to form a rear axle part of a vehicle.