Embodiments of the invention generally relate to a damper assembly for a vehicle. More specifically, certain embodiments relate to spring preload adjustment used in conjunction with a vehicle suspension.
Vehicle suspension systems typically include a spring component or components and a damping component or components. Typically, mechanical springs, like helical springs, are used with some type of viscous fluid-based damping mechanism and the two are mounted functionally in parallel. In some instances, features of the damper or spring are user-adjustable. What is needed is an improved method and apparatus for varying spring preload characteristics.
The present invention generally includes a shock absorber for a vehicle having a damper and a first and second springs mounted coaxially around the damper and a preload adjuster for partially compressing at least one of the springs independently of the compression stroke. In one embodiment the preload adjuster is remotely controllable. In another embodiment the shock absorber includes an additional mechanism for preloading at least one of the springs.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
As used herein, the terms “down,” “up,” “downward,” “upward,” “lower,” “upper” and other directional references are relative and are used for reference only.
A reservoir (not shown) is typically in fluid communication with the damper cylinder 102 for receiving and supplying damping fluid as the piston rod 107 moves in and out of the cylinder. The reservoir includes a cylinder portion in fluid communication with the damper cylinder 102. Certain features of reservoir type dampers are shown and described in U.S. Pat. No. 7,374,028, which is incorporated herein, in its entirety, by reference. One end of the piston rod 107 is supplied with an eyelet 109 for connecting to a portion of a vehicle wheel suspension linkage. An opposite end (opposite the piston), is supplied with an eyelet 111 to be mounted to another portion of the vehicle, such as the frame, that moves independently of the first part.
In one embodiment, as shown in all of the figures, a closure 110, is constructed and arranged to thread onto an end of cylinder 102 and engage telescopically with a preload piston 120. The preload piston is slidable relative to and sealed against (by seal 131) an exterior surface of cylinder 102 and is also slidably sealed against an exterior of the closure 110 by seal 132.
The preload piston includes two separate spring axial abutment structures. Shown are large diameter abutment 115 and a small diameter abutment 130. A spring abutment 125 is attached at an opposite end of rod 107, adjacent a lower connecting eye. As shown in the figures, abutment 125 may be stepped with two surfaces 126, 127 and of sufficient diameter to support either the lower end of a large diameter spring 150 or a small diameter spring 155 or both simultaneously (as shown).
In one embodiment, a preload adjuster assembly includes a hydraulic fluid flow path comprising fill fitting 160, flow path 161, 162 and piston chamber 163 (visible in
In the embodiment shown in the Figures, both springs 150, 155 are acted upon by the preload piston 120 causing both to become more or less compressed as the preload piston 120 moves in relation to the fluid in chamber 163. However, it will be understood that either of the springs could be independently mounted wherein it is not affected at all by the expansion and contraction of the chamber 163.
While the embodiment described presumes chamber 163 of the preload adjuster is operated with relatively non-compressible fluid, compressible fluid such as gas may be used in the chamber to create a composite spring rate comprising compressible gas and mechanical spring.
While the embodiment described includes springs coaxially arranged around a fluid damper, the spring could be used in conjunction with an air spring, especially one that is combined in a central cylinder member with a damper. An example of a combination air spring/damper is taught in U.S. Patent Application Publication No. 2009/0236807 A1 and that publication is incorporated herein in its entirety.
In the embodiment shown, large diameter abutment 115 holding larger diameter spring 150 at one end is independently adjustable relative to the other spring 155 and the chamber. Independent adjustment is provided by a threaded relationship 156 between the abutment 115 and the outer diameter of the chamber. For example, in
The preload adjuster may be automated such that onboard load sensing associated with a vehicle adjusts the spring rate based on sensed operational conditions and microprocessor-controlled fluid introduction into one or more preload adjusters on the vehicle (e.g. 4 on a 4 wheeler),
A remotely operable preload adjuster like the one described above is particularly useful with on/off road vehicles. These vehicles can have as much as 20″ of shock absorber travel to permit them to negotiate rough, uneven terrain at speed with usable shock absorbing function. In off-road applications, compliant shock absorbing is necessary as the vehicle relies on its long travel suspension when encountering off-road obstacles. However, operating a vehicle with very compliant, long travel suspension on a smooth road at higher speeds can be problematic due to the springiness/sponginess of the suspension. Such compliance can cause reduced handling characteristics and even loss of control. Such control issues can be pronounced when cornering at high speed as a compliant, long travel vehicle may tend to roll excessively. Similarly, such a vehicle may pitch and yaw excessively during braking and acceleration. With the remotely operated preload adjuster described herein, spring characteristics of a shock absorber can be completely changed from a compliantly dampened “springy” arrangement to a “stiffer” system ideal for higher speeds on a smooth road.
In addition to, or in lieu of, the simple, switch operated preload adjuster arrangement of
In one embodiment, the magnetic transducer includes a waveguide and a magnet, such as a doughnut (toroidal) magnet that is joined to the cylinder and oriented such that the magnetic field generated by the magnet passes through the piston rod and the waveguide. Electric pulses are applied to the waveguide from a pulse generator that provides a stream of electric pulses, each of which is also provided to a signal processing circuit for timing purposes. When the electric pulse is applied to the waveguide a magnetic field is formed surrounding the waveguide. Interaction of this field with the magnetic field from the magnet causes a torsional strain wave pulse to be launched in the waveguide in both directions away from the magnet. A coil assembly and sensing tape is joined to the waveguide. The strain wave causes a dynamic effect in the permeability of the sensing tape which is biased with a permanent magnetic field by the magnet. The dynamic effect in the magnetic field of the coil assembly due to the strain wave pulse, results in an output signal from the coil assembly that is provided to the signal processing circuit along signal lines. By comparing the time of application of a particular electric pulse and a time of return of a sonic torsional strain wave pulse back along the waveguide, the signal processing circuit can calculate a distance of the magnet from the coil assembly or the relative velocity between the waveguide and the magnet. The signal processing circuit provides an output signal, digital or analog, proportional to the calculated distance and I or velocity. Such a transducer-operated arrangement for measuring rod speed and velocity is described in U.S. Pat. No. 5,952,823 and that patent is incorporated by reference herein in its entirety.
While a transducer assembly measures rod speed and location, a separate wheel speed transducer for sensing the rotational speed of a wheel about an axle includes housing fixed to the axle and containing therein, for example, two permanent magnets. In one embodiment the magnets are arranged such that an elongated pole piece commonly abuts first surfaces of each of the magnets, such surfaces being of like polarity. Two inductive cons having flux-conductive cores axially passing therethrough abut each of the magnets on second surfaces thereof, the second surfaces of the magnets again being of like polarity with respect to each other and of opposite polarity with respect to the first surfaces. Wheel speed transducers are described in U.S. Pat. No. 3,986,118 which is incorporated herein by reference in its entirety.
In one embodiment, as illustrated in
In one embodiment, the logic shown in
While the examples illustrated relate to manual operation and automated operation based upon specific parameters, the remotely operated preload adjuster can be used in a variety of ways with many different driving and road variables. In one example, the preload adjuster is controlled based upon vehicle speed in conjunction with the angular location of the vehicle's steering wheel. In this manner, by sensing the steering wheel turn severity (angle of rotation), additional stiffness can be applied to one shock or one set of shocks on one side of the vehicle (suitable, for example, to mitigate cornering roll) in the event of a sharp turn at a relatively high speed. In another example, a transducer, such as an accelerometer, measures other aspects of the vehicle's suspension system, like axle force and/or moments applied to various parts of the vehicle, like steering tie rods, and directs change to the preload adjuster positioning in response thereto. In another example, the preload adjuster can be controlled at least in part by a pressure transducer measuring pressure in a vehicle tire and adding or subtracting stiffness characteristics to some or all of the wheels in the event of, for example, an increased or decreased pressure reading. In still another example, a parameter might include a gyroscopic mechanism that monitors vehicle trajectory and identifies a “spin-out” or other loss of control condition and adds and/or reduces spring stiffness to some or all of the vehicle's shock absorbers in the event of a loss of control to help the operator of the vehicle to regain control.
While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims priority to and is a continuation of the co-pending patent application Ser. No. 16/442,186, entitled “SUSPENSION WITH HYDRAULIC PRELOAD ADJUST,” with filing date Jun. 14, 2019, by Christopher Paul Cox, which is incorporated herein, in its entirety, by reference. The application with Ser. No. 16/442,186 claims priority to and is a continuation of the patent application Ser. No. 15/948,634 and now issued U.S. Pat. No. 10,336,151, entitled “SUSPENSION WITH HYDRAULIC PRELOAD ADJUST,” with filing date Apr. 9, 2018, by Christopher Paul Cox, which is incorporated herein, in its entirety, by reference. The application with Ser. No. 15/948,634 claims priority to and is a continuation of the patent application Ser. No. 15/471,986 and now issued U.S. Pat. No. 9,969,236, entitled “SUSPENSION WITH HYDRAULIC PRELOAD ADJUST,” with filing date Mar. 28, 2017, by Christopher Paul Cox, which is incorporated herein, in its entirety, by reference. The application with Ser. No. 15/471,986 claims priority to and is a continuation of the patent application Ser. No. 14/995,098 and now issued U.S. Pat. No. 9,623,716, entitled “SUSPENSION WITH HYDRAULIC PRELOAD ADJUST,” with filing date Jan. 13, 2016, by Christopher Paul Cox, which is incorporated herein, in its entirety, by reference. The application with Ser. No. 14/995,098 claims priority to and is a continuation of the patent application Ser. No. 14/293,927 and now issued U.S. Pat. No. 9,248,717, entitled “SUSPENSION WITH HYDRAULIC PRELOAD ADJUST,” with filing date Jun. 2, 2014, by Christopher Paul Cox, which is incorporated herein, in its entirety, by reference. The application with Ser. No. 14/293,927 claims priority to and is a continuation of the patent application Ser. No. 13/758,330 and now issued U.S. Pat. No. 8,770,592, entitled “SUSPENSION WITH HYDRAULIC PRELOAD ADJUST,” with filing date Feb. 4, 2013, by Christopher Paul Cox, which is incorporated herein, in its entirety, by reference. The application with Ser. No. 13/758,330 claims priority to the patent application, Ser. No. 61/594,886, entitled “SUSPENSION WITH HYDRAULIC PRELOAD ADJUST,” with filing date Feb. 3, 2012, by Christopher Paul Cox, which is incorporated herein, in its entirety, by reference.
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