INDEPENDENT INTEGRAL FIVE-LINK SUSPENSION SYSTEMS

Abstract

Independent five-link suspension system for a motor vehicle, comprising: a steering knuckle (30, 130) arranged in an interior space of a rear wheel of the vehicle, the steering knuckle (30, 130) having an upper end facing the vehicle body and a lower end facing the road surface; a tie rod (16, 116) having a first end connected to the steering knuckle (30, 130) and a second end connected to a frame member (22, 122) of the vehicle; a track rod (18, 118) having a first end connected to the steering knuckle (30, 130) and a second end connected to the frame member (22, 122); a spring link (20, 120) having a first end connected to the steering knuckle (30, 130) and a second end connected to the frame member (22, 122) connected second end;a longitudinal control arm (12, 112) comprising a first end connected to a lower end of the steering knuckle (30, 130) and a second end connected to the frame support (22, 122), wherein the longitudinal control arm (12, 112) extends along a single axis between the steering knuckle (30, 130) and the frame support (22, 122); and an integral link (150), comprising a first end connected to the steering knuckle (30, 130) above the longitudinal control arm (12, 112) and a second end connected to the longitudinal control arm (12, 112), wherein the first end of the integral link (150) is connected to the steering knuckle (30, 130) at a point closer to the lower end of the steering knuckle (30, 130) than to the upper end of the steering knuckle (30, 130), wherein the first ends of the tie rod (16, 116), the track link (18, 118), the spring link (20, 120), the longitudinal control arm (12, 112) and the integral link (150) are connected to the steering knuckle (30, 130) at different points thereon.

Description

The present disclosure relates to independent five-link suspension systems according to claims 1 or 9. A vehicle suspension system plays a crucial role, both in isolating vehicle occupants from road surface irregularities and in helping control vehicle stability by managing the relative position of the wheels to the vehicle body during operation. Suspension systems are divided into two main categories: dependent and independent. These terms refer to the ability of opposing wheels (i.e., wheels on the same axle) to move independently. Generally, in a dependent suspension, the movement of one wheel affects the orientation of the opposite wheel. In contrast, an independent suspension allows each wheel to move freely without interference from the opposite wheel, enabling the wheels to react individually to undulations in the road surface.For example, an independent rear suspension (IRS) allows the rear wheels of the vehicle to be sprung independently. IRS systems can also take various forms, including, for example, a double wishbone suspension, a multi-link suspension, and an integral link suspension. A double wishbone suspension, for instance, has two sets of lateral wishbones, commonly referred to as upper and lower wishbones, and track rods. Each wishbone has two attachments to the body and a single attachment to the steering knuckle (or wheel carrier). The three steering knuckle attachments (upper link, lower link, and track rod) on each side establish the plane of each wheel and, in response to wheel loads, control both camber and toe angles. Each side is isolated from the other half, which serves to isolate each wheel's response to the road surface independently. A refined form of the double wishbone suspension is the multi-link suspension, which conceptually divides the structural performance of each wishbone into two tension / compression links. Thus, a conventional five-link suspension system can be visualized as splitting the upper wishbone into an upper trailing arm and a tie rod, splitting the lower wishbone into a lower control arm and a spring link, and retaining the track rod. The orientation and length of each link determine its geometric performance as well as the level of link stress when responding to wheel forces. An integral link suspension connects a steering knuckle to an isolated subframe via a lower control arm, a tie rod, and a track rod. The steering knuckle is directly connected to the lower control arm via a pivot point and indirectly via an additional link, the integral link. The integral link can, for example, separate caster compliance from longitudinal compliance, thus eliminating the need for a trailing arm or a trailing arm. An integral link rear suspension is therefore softer in terms of its wheel flex rate compared to a conventional five-link suspension, stiffer in terms of caster stiffness, and allows for a smaller rear body support structure for increased interior space (since there is no upper trailing arm).Accordingly, the integral link suspension can ensure a significant reduction in interior noise while driving, while at the same time significantly improving impact roughness and rebound compared to the conventional five-link suspension, and without impairing the vehicle's handling. Although an integral link suspension system has several advantages over the conventional five-link suspension system, a conventional integral link suspension usually costs and weighs considerably more than the five-link suspension (which uses an assembly of relatively light and inexpensive dual-force links), making its use often impractical for standard applications. Therefore, it can be advantageous to provide an IRS system that functions like an integral link suspension system (providing the benefits of the integral link system over the conventional five-link system), while maintaining costs and weight similar to those of the conventional five-link system. Further prior art can be found in document WO 2014 202 300 A1. This relates to a wheel suspension for a motor vehicle with a wheel carrier for receiving a wheel, a wheel-guiding link for articulatedly connecting the wheel carrier to a designated structure, and a steering device for steering the wheel, wherein the wheel carrier and the wheel-guiding link are articulated to each other such that the wheel carrier is pivotable about a steering axis relative to the wheel-guiding link. According to the invention, the wheel carrier is indirectly connected to the link in a first connection area via an integral link. The object underlying the invention is to provide five-link suspension systems that combine at least some of the described advantages of known suspension systems and at least some of the described disadvantages. This problem is solved by the subject matter of independent claims 1 and 9. Further, particularly advantageous embodiments of the invention are disclosed in the respective dependent claims. According to various exemplary embodiments, the present disclosure provides an independent five-link suspension system for a motor vehicle. According to various embodiments of the present disclosure, the independent five-link suspension system comprises a steering knuckle and a trailing arm extending along a single axis. The trailing arm is connected to the steering knuckle and configured for attachment to a frame member of the vehicle. The suspension system further comprises an integral link connected to the steering knuckle and configured for attachment to the trailing arm. According to various additional embodiments of the present disclosure, an independent five-link suspension system for a motor vehicle includes a steering knuckle arranged in an interior space of a rear wheel of the vehicle. The suspension system also includes a trailing arm connected to the lower end of the steering knuckle and extending along a single axis between the steering knuckle and a frame member of the vehicle. The suspension system further includes an integral link connected to the steering knuckle above the trailing arm and extending between the steering knuckle and the trailing arm. Additional tasks and benefits of the revelation are partly listed in the following description and partly evident from the description itself or can be learned through the application of the revelation. The tasks and benefits of the revelation are realized and achieved through the elements and combinations shown, in particular, in the appended claims. It is understood that both the preceding general description and the following detailed description are purely exemplary and illustrative and do not limit the claimed disclosure. The accompanying drawings, which are included in and form part of this patent specification, show embodiments of the disclosure and, together with the description, serve to explain the basic features of the disclosure. At least some features and advantages will become apparent from the following detailed description of the corresponding embodiments, the description being considered with reference to the accompanying drawings, in which: Fig. 1 shows a perspective view of a conventional independent five-link rear suspension system; Fig. 2 shows a perspective view of an exemplary embodiment of an independent integral five-link rear suspension system according to the present disclosure; Fig. 3 shows a diagram comparing the caster compliance of a modeled independent integral five-link rear suspension system according to the present disclosure with the modeled conventional independent five-link and integral-link rear suspension systems; Fig.Figure 4 shows a diagram comparing the compliance of the modeled independent integral five-link rear suspension system with the modeled conventional independent five-link and integral link rear suspension system; and Figure 5 shows a schematic view of a vehicle wheel showing a caster angle. Although the following detailed description refers to exemplary embodiments, many alternatives, modifications, and variations thereof are apparent to a person skilled in the art. Accordingly, the claimed subject matter of the invention shall be considered in general terms. Various embodiments will now be discussed in detail, examples of which are shown in the accompanying drawings. These exemplary embodiments are not intended to limit the disclosure. On the contrary, the disclosure is intended to cover alternatives, modifications, and equivalents. According to various exemplary embodiments, the present disclosure provides an independent rear suspension system (IRS system) for a motor vehicle that functions similarly to a conventional integral link suspension system, while its cost and weight are similar to those of a conventional five-link suspension system. For example, the exemplary embodiments described herein employ a five-link suspension architecture to utilize five relatively lightweight, cost-effective dual-force links, while improving ride comfort and noise by decoupling caster stiffness from the wheel return rate.Various exemplary embodiments described herein include, for example, an independent five-link suspension system comprising an integral link that decouples caster compliance from longitudinal compliance (rebound compliance), thereby providing cornering, handling and steering behavior of a conventional five-link suspension architecture, but with the longitudinal isolation associated with the more comfortable suspension design of the conventional integral link suspension architecture. As would be obvious to the average person, caster, when referring to a wheel of a motor vehicle, is the angle θ (see Fig. 5) at which the steering axis, viewed from the side of the wheel, is inclined forward or backward from the vertical. Therefore, caster stiffness refers to the side-view mounting stiffness or torsional stiffness (the ratio of applied torsional moment to angle of twist) of the wheel due to a longitudinal load (i.e., acceleration / braking force) applied to the contact patch of the tire with the road. Furthermore, caster compliance is the opposite of caster stiffness and refers to the rotational displacement of the steering axis when an acceleration / braking force is applied to the contact patch (displacement / force). Wheel deflection rate refers to the wheel center stiffness (force / displacement) due to a longitudinal load (i.e., acceleration / braking force) applied to the wheel center. Deflection compliance, or longitudinal compliance, is therefore the opposite of wheel deflection rate and refers to the backward displacement of the wheel when a force is applied in that direction (displacement / force). As an average expert would further understand, there is therefore an inherent trade-off between the longitudinal compliance and the caster compliance of a vehicle suspension system. A certain degree of longitudinal compliance is generally desirable (that is, a softer wheel return rate) to enable the suspension to absorb longitudinal force inputs associated with, for example, a rough road surface (such as potholes). However, the associated caster compliance (that is, a soft caster stiffness) is generally undesirable, as it can reduce the stability of the vehicle's steering when the steering axis rotates and the caster angle and caster distance (that is, the side-view horizontal distance from the point where the steering axis intersects the road surface to the center of the contact patch) are reduced. Fig. 1 shows an exemplary arrangement of the components of a conventional five-link IRS system 10. The IRS system 10 comprises a lower trailing arm 12, an upper trailing arm 14, a tie rod 16, a track rod 18, and a spring link 20, all connected to a steering knuckle 30. As the average person skilled in the art would understand, the lower and upper trailing arms 12 and 14 form the longitudinal linkages that serve to position the wheel longitudinally and to respond to tensile loads and braking torques when the IRS system is in use. As shown in Fig. 1, the upper and lower trailing arms 12 and 14, when in use, are located within the envelope of a frame member 22 of a motor vehicle (not shown) and extend between the steering knuckle 30 and the frame member 22 (to which the trailing arms 12 and 14 are also attached).As an average professional would further understand, the tie rod 16, the track link 18 and the spring link 20 form the part of the IRS system 10 that establishes the wheel plane alignment and reacts to vertical and lateral loads. Fig. 2 shows an exemplary embodiment of an integral five-link IRS system 100 according to the present disclosure. Similar to the conventional five-link IRS system 10 shown in Fig. 1, the IRS system 100 includes a trailing arm 112 (similar to the lower trailing arm 12), a tie rod 116, a track rod 118, and a spring link 120, all of which are connected to a steering knuckle 130 via, for example, respective flanges 132, 136, 138, and 140. However, unlike the conventional IRS system 10, IRS systems according to the present disclosure do not have an upper trailing arm (for example, the upper trailing arm 14), but instead provide for the use of an integral link positioned between the lower trailing arm and the steering knuckle. As shown in Fig.As shown in Figure 2, the IRS system 100, for example in various embodiments, includes an integral link 150 which is connected to the steering knuckle via a flange 134 above the longitudinal link 112. In various embodiments of the present disclosure, for example, the longitudinal control arm 112, the integral control arm 150, the tie rod 116, the track link 118 and the spring link 120 each comprise a dual-force tension / compression link with respective rubber bushings 113, 115, 117, 119 and 121 at each of their respective ends (which, for example, is connected at one end to the respective flange 132, 134, 136, 138 and 140 of the steering knuckle 130). However, the average person skilled in the art would understand that the IRS system 100 of Fig. 2 is purely exemplary and that the control arms 112, 150, 116, 118 and 120 and the steering knuckle 130 to which the control arms are connected may have various alternative configurations (i.e. shapes and / or cross-sections), lengths, dimensions and / or connection points without deviating from the scope of protection of the present disclosure and the claims.In various additional embodiments, the spring link 120 can, for example, also support a vertical load. In various further embodiments, the integral link 150 can be connected to the steering knuckle 130 below the longitudinal link 112. Furthermore, the links 112, 150, 116, 118, and 120 and the steering knuckle 130 can be configured to be connected by any method and / or technique known to the person skilled in the art and are not limited to the flanges and bushings shown in Fig. 2. In various embodiments, the links 112, 150, 116, 118, and 120 can, for example, be connected to the steering knuckle 130 via a ball joint, although this is not shown. According to various exemplary embodiments of the present disclosure, when using the IRS system 100, the steering knuckle 130 is arranged, according to its configuration, in an interior space of a rear wheel (not shown) of a motor vehicle (not shown). When using the IRS system 100, the tie rod 116, the track link 118, and the spring link 120 are accordingly arranged, as shown in Fig. 2, substantially laterally with respect to a longitudinal axis (not shown) of the motor vehicle, and the trailing arm 112 and the integral link 150 are, according to their configuration, substantially longitudinally with respect to the longitudinal axis of the motor vehicle. As shown in Fig. 2, when using the IRS system 100, the longitudinal control arm 112 is connected to a lower end of the steering knuckle 130 via the flange 132 and extends along a single axis between the steering knuckle 130 and a frame member 122 of the vehicle. The integral link 150 is positioned to extend between the steering knuckle 130 and the longitudinal control arm 112. The steering knuckle 130 is therefore directly connected to the frame member 122 via the longitudinal control arm 112 and indirectly via the integral link 150. In this way, the integral link 150 can decouple caster stiffness or the pull-back stiffness associated with the steering knuckle 130 from the wheel return rate.Since the integral link 150 is not connected to the frame support 122, in various embodiments, for example, the bushing 115, which connects the integral link 150 to the flange 134 of the steering knuckle 130, can be rigid to counteract the rotation of the steering knuckle 130 without affecting the ability of the suspension system 100 to absorb longitudinal forces. As used herein, the term ‘frame support’ refers to any type of vehicle frame support, including but not limited to supports forming the main structure of the vehicle chassis and subframe supports forming frame sections attached to the chassis. To verify the expected compliance of the suspension systems according to the present disclosure, an integral five-link suspension system according to the present disclosure, similar to the IRS suspension system 100 shown and described above with reference to Fig. 2, was modeled in Adams, a multibody dynamics (MBD) simulation software from MSC Software®. A conventional five-link suspension system and a conventional integral link suspension system were also modeled in Adams for comparison purposes. Figure 3 is a diagram comparing the caster compliance of the modeled independent integral five-link suspension system with the modeled independent conventional five-link and integral link rear suspension systems. As shown in Figure 3, the caster compliance of the integral five-link suspension system was stiffer (thus providing better vehicle steering stability) than the conventional five-link suspension system and similar to the conventional integral link suspension system. Figure 4 is a diagram comparing the rebound compliance of the modeled independent integral five-link rear suspension system with the modeled conventional independent five-link and integral link rear suspension systems. As shown in Figure 4, the rebound compliance of the integral five-link suspension system was softer (allowing the suspension system to better absorb longitudinal forces) than the conventional five-link suspension system and stiffer than the conventional integral link suspension system. Therefore, it was determined that the disclosed integral five-link suspension system can provide a relatively stiff caster stiffness, similar to that of the conventional integral link suspension system (for example, within approximately 10%), and a relatively soft wheel return rate, somewhere between that of the conventional integral five-link and integral link suspension systems (for example, within the adjustment range for competing integral link systems). Integral five-link suspension systems according to the present disclosure can, for example, be approximately 50% to approximately 80% stiffer with respect to caster stiffness, while their wheel return rate is approximately 30% to approximately 50% softer than that of a conventional five-link suspension system. Accordingly, integral five-link suspension systems according to the present disclosure can effectively decouple caster and lateral compliance, thereby providing the cornering, handling, and steering characteristics of the relatively lightweight and inexpensive conventional five-link suspension system, but with the longitudinal isolation associated with the more expensive and heavy integral link suspension system. For example, integral five-link suspension systems according to the present disclosure can weigh approximately 10% to approximately 30% less and cost approximately 10% to approximately 20% less to manufacture than a conventional integral link suspension system. Similar to the conventional integral link suspension system, integral five-link suspension systems according to the present disclosure further feature an upper trailing arm, which allows the vehicle's loading platform to be reduced in height compared to a conventional five-link suspension system (which uses an upper trailing arm). Integral five-link suspension systems according to the present disclosure can, for example, allow the loading platform to be approximately 50 mm to approximately 75 mm lower than with a conventional five-link suspension system, thus providing greater flexibility in suspension design and performance during suspension packaging. Accordingly, integral five-link suspension systems according to the present disclosure can function like a conventional integral link suspension system (and offer the advantages of the integral link system over the conventional five-link system), while their cost and weight are similar to those of the conventional five-link suspension system. Although the present disclosure has been made available by way of exemplary embodiments to facilitate a better understanding of the disclosure, it should be obvious that the disclosure can be implemented in a wide variety of ways without deviating from the fundamental features of the disclosure. Therefore, the disclosure should be understood comprehensively as encompassing all possible embodiments that can be implemented without deviating from the fundamental features of the disclosure set forth in the appended claims. Furthermore, although the present disclosure has been discussed with reference to automobiles, it would be obvious to a person skilled in the art that the teachings presented here, as disclosed, work equally well for any type of vehicle with one or more wheels connected to the vehicle via a suspension system. For the purposes of this description and the attached claims, unless otherwise specified, all numbers expressing quantities, percentages, or proportions, and other numerical values ​​used in the description and the claims, shall be understood as being modified by the term "approximately" in all cases. Accordingly, unless otherwise specified, the numerical parameters stated in the written description and the written claims are an approximation that may vary depending on the desired properties that the present invention aims to achieve. Each numerical parameter shall be interpreted, at a minimum, and not as an attempt to limit the application of the equivalence doctrine to the scope of the claims, at least with regard to the number of significant figures reported and by applying ordinary rounding techniques. It should be noted that, according to their use in the present description and in the appended claims, the singular forms "ein," "eine," and "der," "die," "das" also include multiple reference objects unless they are expressly and unambiguously limited to only one reference object. Thus, for example, the reference to "ein Sensor" includes two or more different sensors. As used herein, the term "include" and its grammatical variants are not intended to be restrictive, so that an enumeration of objects in a list does not exclude other similar objects with which the listed objects can be exchanged or which can be added to them. It is understood by those skilled in the art that various modifications and variations of the system and method of the present disclosure can be carried out without deviating from the scope of protection of its teachings. Other embodiments of the disclosure become apparent to those skilled in the art when considering the description and application of the teachings disclosed herein. It is intended that the description and embodiment described herein should be regarded as purely exemplary.

Claims

Independent five-link suspension system for a motor vehicle, comprising: a steering knuckle (30, 130) arranged in an interior space of a rear wheel of the vehicle, the steering knuckle (30, 130) having an upper end facing the vehicle body and a lower end facing the road surface; a tie rod (16, 116) having a first end connected to the steering knuckle (30, 130) and a second end connected to a frame member (22, 122) of the vehicle; a track rod (18, 118) having a first end connected to the steering knuckle (30, 130) and a second end connected to the frame member (22, 122); a spring link (20, 120) having a first end connected to the steering knuckle (30, 130) and a second end connected to the frame member (22, 122) connected second end;a longitudinal control arm (12, 112) comprising a first end connected to a lower end of the steering knuckle (30, 130) and a second end connected to the frame support (22, 122), wherein the longitudinal control arm (12, 112) extends along a single axis between the steering knuckle (30, 130) and the frame support (22, 122); and an integral link (150), comprising a first end connected to the steering knuckle (30, 130) above the longitudinal control arm (12, 112) and a second end connected to the longitudinal control arm (12, 112), wherein the first end of the integral link (150) is connected to the steering knuckle (30, 130) at a point closer to the lower end of the steering knuckle (30, 130) than to the upper end of the steering knuckle (30, 130), wherein the first ends of the tie rod (16, 116), the track link (18, 118), the spring link (20, 120), the longitudinal control arm (12, 112) and the integral link (150) are connected to the steering knuckle (30, 130) at different points thereon. Suspension system according to claim 1, wherein the tie rod (16, 116), the track link (18, 118), the spring link (20, 120), the longitudinal link (12, 112) and the integral link (150) each have a rubber bushing (113, 115, 117, 119, 121) at each of their respective ends. Suspension system according to claim 1, wherein the tie rod (16, 116), the track link (18, 118), the spring link (20, 120), the longitudinal link (12, 112) and the integral link (150) comprise a tension / compression link. Suspension system according to claim 3, wherein the spring link (20, 120) supports a vertical load. Suspension system according to claim 1, wherein the tie rod (16, 116), the track link (18, 118) and the spring link (20, 120) are arranged substantially laterally with respect to a longitudinal axis of the motor vehicle. Suspension system according to claim 1, wherein the longitudinal link (12, 112) and the integral link (150) are arranged substantially in the longitudinal direction with respect to a longitudinal axis of the motor vehicle. Suspension system according to claim 1, wherein the integral link (150) is configured to decouple caster stiffness from the wheel return rate. Suspension system according to claim 1, wherein the integral link (150) is configured to counteract rotation of the steering knuckle (30, 130). Independent five-link suspension system for motor vehicles, comprising: a steering knuckle (30, 130), a tie rod (16, 116), a track link (18, 118), a spring link (20, 120) and an integral link (150); and a longitudinal control arm (12, 112) extending along a single axis, wherein the tie rod (16, 116), track link (18, 118), spring link (20, 120), integral link (150) and longitudinal link (12, 112) each have a first end, the first ends being connected to the steering knuckle (30, 130) at different locations therein, the second ends of the tie rod (16, 116), the track link (18, 118), the spring link (20, 120) and the longitudinal link (12, 112) being arranged for connection to a frame member (22, 122), and the second end of the integral link (150) being connected to the longitudinal link (12, 112). Suspension system according to claim 9, wherein this is further developed with those features specified in one or more of claims 2 to 8.

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