The field of the present disclosure generally relates to vehicle suspension systems. More particularly, the field of the invention relates to a leading-edge front suspension system configured to improve the mechanical strength and performance of off-road drivetrains.
A double wishbone suspension is a well-known independent suspension design using upper and lower wishbone-shaped arms to operably couple a front wheel of a vehicle. Typically, the upper and lower wishbones or suspension arms each has two mounting points to a chassis of the vehicle and one mounting joint at a spindle assembly or knuckle. A shock absorber and a coil spring may be mounted onto the wishbone to control vertical movement of the front wheel. The double wishbone suspension facilitates control of wheel motion throughout suspension travel, including controlling such parameters as camber angle, caster angle, toe pattern, roll center height, scrub radius, scuff, and the like.
Double wishbone suspensions may be used in a wide variety of vehicles, including heavy-duty vehicles, as well as many off-road vehicles, as shown in
The double-wishbone suspension often is referred to as “double A-arms”, although the arms may be A-shaped, L-shaped, J-shaped, or even a single bar linkage. In some embodiments, the upper arm may be shorter than the lower arm so as to induce negative camber as the suspension jounces (rises). Preferably, during turning of the vehicle, body roll imparts positive camber gain to the lightly loaded inside wheel, while the heavily loaded outer wheel gains negative camber.
The spindle assembly, or knuckle, is coupled between the outboard ends of the upper and lower suspension arms. In some designs, the knuckle contains a kingpin that facilitates horizontal radial movement of the wheel, and rubber or trunnion bushings for vertical hinged movement of the wheel. In some relatively newer designs, a ball joint may be disposed at each outboard end to allow for vertical and radial movement of the wheel. A bearing hub, or a spindle to which wheel bearings may be mounted, may be coupled with the center of the knuckle.
Constant velocity (CV) joints allow pivoting of the suspension arms and the spindle assembly, while a drive shaft coupled to the CV joint delivers power to the wheels. Although CV joints are typically used in front wheel drive vehicles, off-road vehicles such as four-wheeled buggies comprise CV joints at all wheels. Constant velocity joints typically are protected by a rubber boot and filled with molybdenum disulfide grease.
Given that off-road vehicles routinely travel over very rough terrain, such as mountainous regions, there is a desire to improve the mechanical strength and performance of off-road drivetrain and suspension systems, while at the same reducing the mechanical complexity of such systems.
An apparatus and methods are provided for a leading-edge front suspension system to improve the mechanical strength and performance of off-road vehicles. The leading-edge front suspension system comprises upper and lower connecting arms that couple front wheels with a chassis of a vehicle. The upper and lower connecting arms are swept rearward relative to the chassis so as to accommodate coupling struts between the lower connecting arms and the chassis. The lower connecting arms are reinforced to withstand forces arising due to the front wheels and the struts during traveling over terrain. The upper connecting arms are configured to accommodate the struts extending between the lower connecting arms and the chassis. Experimental observations have demonstrated that coupling the struts with the lower connecting arms facilitates a lower center of gravity of the off-road vehicle and advantageously positions the struts with respect to the lower connecting arms during full compression of the struts.
In an exemplary embodiment, a leading-edge front suspension system for an off-road vehicle comprises: a spindle assembly coupled with each front wheel; an upper connecting arm hingedly coupling a top of the spindle assembly with a chassis; a lower connecting arm hingedly coupling a bottom of the spindle assembly with the chassis; and a strut coupled between the lower connecting arm and the chassis.
In another exemplary embodiment, the upper connecting arm includes two inboard mounting joints to the chassis and one outboard mounting joint to the spindle assembly. In another exemplary embodiment, the inboard mounting joints are bushing joints configured to allow vertical movement of the upper connecting arm with respect to the chassis. In another exemplary embodiment, the outboard mounting joints comprise rod-end joints configured to allow vertical and horizontal movement of the spindle assembly with respect to the chassis.
In another exemplary embodiment, the upper connecting arm includes a sweep angle that positions the outboard mounting joint rearward of a midpoint between the inboard mounting joints. In another exemplary embodiment, the sweep angle is configured to accommodate the strut extending between the lower connecting arm and the chassis and position the outboard mounting joint to be coupled with the spindle assembly. In another exemplary embodiment, the inboard mounting joints are positioned forward of inboard mounting joints comprising the lower connecting arm such that the sweep angle is greater that a sweep angle of the lower connecting arm.
In another exemplary embodiment, the lower connecting arm includes two inboard mounting joints to the chassis and one outboard mounting joint to the spindle assembly. In another exemplary embodiment, the inboard mounting joints are bushing joints configured to allow vertical movement of the lower connecting arm with respect to the chassis. In another exemplary embodiment, the outboard mounting joints comprise rod-end joints configured to allow vertical and horizontal movement of the spindle assembly with respect to the chassis. In another exemplary embodiment, the lower connecting arm includes a lower pivot configured to receive the strut. In another exemplary embodiment, the lower connecting arm is reinforced to withstand forces arising due to the front wheel and the strut during traveling over terrain. In another exemplary embodiment, the lower connecting arm is swept rearward at an angle relative to the chassis so as to accommodate receiving the strut. In another exemplary embodiment, the outboard mounting joint is positioned rearward of a midpoint between the inboard mounting joints, giving the lower connecting arm a sweep angle.
In an exemplary embodiment, a method for a leading-edge front suspension system for an off-road vehicle comprises: coupling a spindle assembly with each front wheel; configuring an upper connecting arm to hingedly couple a top of the spindle assembly with a chassis; configuring a lower connecting arm to hingedly couple a bottom of the spindle assembly with the chassis; and mounting a strut between the lower connecting arm and the chassis.
In another exemplary embodiment, configuring the upper connecting arm includes forming a rearward sweep angle comprising the upper connecting arm so as to accommodate the strut extending between the lower connecting arm and the chassis. In another exemplary embodiment, configuring the upper connecting arm includes mounting the upper connecting arm to the chassis in a position forward of the lower connecting arm. In another exemplary embodiment, configuring the lower connecting arm includes reinforcing the lower connecting arm to withstand forces arising due to the front wheel and the strut during traveling over terrain. In another exemplary embodiment, configuring the lower connecting arm includes forming a rearward sweep angle comprising the lower connecting arm so as to accommodate receiving the strut.
These and other features of the concepts provided herein may be better understood with reference to the drawings, description, and appended claims.
The drawings refer to embodiments of the present disclosure in which:
While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The invention should be understood to not be limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one of ordinary skill in the art that the invention disclosed herein may be practiced without these specific details. In other instances, specific numeric references such as “first joint,” may be made. However, the specific numeric reference should not be interpreted as a literal sequential order but rather interpreted that the “first joint” is different than a “second joint.” Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present disclosure. The term “coupled” is defined as meaning connected either directly to the component or indirectly to the component through another component. Further, as used herein, the terms “about,” “approximately,” or “substantially” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein.
In general, the present disclosure describes a suspension for coupling a front wheel with a chassis of an off-road vehicle. The suspension comprises an upper suspension arm that includes two inboard mounting points to the chassis and one outboard rod-end joint to a spindle assembly coupled with the front wheel. A lower suspension arm comprises two inboard mounting points to the chassis and one outboard rod-end joint to the spindle assembly. Each outboard rod-end joint is comprised of a ball that is rotatable within a casing that is threadably coupled with each of the upper and lower suspension arms. A bolt fastens each of the balls between a pair of parallel prongs extending from the spindle assembly, such that the upper and lower suspension arms may pivot with respect to the spindle assembly during vertical motion of the spindle assembly, as well as during horizontal rotation of the spindle assembly due to steering. A strut comprising a shock absorber and a coil spring is coupled between the lower suspension arm and the chassis. The upper suspension arm is configured to facilitate coupling the strut between the lower suspension arm and the chassis. A steering rod is coupled with the spindle assembly by way of a steering rod-end joint that is disposed at a front of the spindle assembly. The steering rod-end joint is comprised of a ball that is rotatable within a casing that is threadably coupled with the steering rod. A pair of parallel prongs and a bolt hingedly couple the steering rod-end with the spindle assembly, such that the steering rod-end joint allows vertical and horizontal rotational motion of the spindle assembly during operation of the off-road vehicle. The steering rod-end joint is coupled with the spindle assembly forward of a drive axle, thereby decreasing leverage of the front wheel on the steering rod and substantially eliminating bump steer that may occur due to rough terrain.
Moreover, it should be understood that although the leading-edge front suspension system 124 is disclosed specifically in connection with the passenger side of the off-road vehicle 100, a driver side front suspension system is to be coupled with a driver side of the off-road vehicle. It should be further understood that the driver side front suspension system is substantially identical to the leading-edge front suspension system 124, with the exception that the driver side front suspension system is configured specifically to operate with the driver side of the off-road vehicle 100. As will be appreciated, therefore, the driver side front suspension system and the suspension system 124 may be configured as reflections of one another across a longitudinal midline of the off-road vehicle 100.
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In some embodiments, coupling the strut 144 with the lower connecting arm 132 positions the strut at between 8 inches and 10 inches lower, with respect to the chassis 116, than the position of the strut when coupled with the upper connecting arm 128. Experimental observation has shown that the lower position of the strut 144 generally facilitates a lower center of gravity of the off-road vehicle 100 and a relatively smaller shock angle, as well as eliminating a need for extending the strut towers through and above a hood of the off-road vehicle 100. In one embodiment, the coupling of the strut 144 with the lower connecting arm 132 positions the strut at substantially 90-degrees with respect to the lower pivot 148 and the upper pivot during full compression of the strut.
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While the invention has been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. To the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well. Therefore, the present disclosure is to be understood as not limited by the specific embodiments described herein, but only by scope of the appended claims.
This application claims the benefit of and priority to U.S. Provisional Application, entitled “Leading-Edge Front Suspension,” filed on Mar. 9, 2020 and having application Ser. No. 62/987,282, the entirety of said application being incorporated herein by reference.
Number | Date | Country | |
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62987282 | Mar 2020 | US |