Monoshock gas suspension system

A suspension system for use with a motorcycle includes a device for producing a supply of pressurized air. The suspension system is operably disposed between a frame member and a wheel frame member of the motorcycle. The suspension system comprises at least one double-acting pneumatic cylinder.

FIELD OF THE INVENTION

This invention generally relates to vehicle suspension systems. More particularly, in an illustrated embodiment, the invention is directed to a gas suspension system for a front or rear suspension component in a motorcycle.

BACKGROUND OF THE INVENTION

In general terms, motorcycles typically include a main frame to which the engine is attached. One or more sub-frames or like elements can be movably attached to the main frame, each of which can be adapted to hold one of the motorcycle wheels. The moving sub-frames may permit the motorcycle front and rear wheels to move relative to the main frame.

Traditionally, motorcycle suspension systems for street bikes have included one or more springs (typically coil springs) and a hydraulic damper unit applied to each of the front and rear wheel to provide the lift and dampening needed to suspend the vehicle and control movement of the wheels during compression and rebound of the wheels. Such a spring and damper unit may be positioned inside a telescoping fork assembly on the front wheel to assist with controlling the front wheel. Another form of a front fork, referred to as a “springer” fork, includes a spring suspension operating between two pairs of parallel fork members in a well known manner.

Still other suspension systems may be employed on the rear wheel of the motorcycle. For example, a spring and damper unit may be fastened between a swing arm and main frame in the rear of the motorcycle to control the rear wheel assembly and associated parts. Other suspension systems may use air in place of or in addition to the spring. These systems are often called air-ride suspension systems, and may use rubber air bags as springs and may further be charged using a compressed air system. Compressed air may be varied to control the ride height and the ride characteristics (i.e. firmness) of the motorcycle. However, the ride will inherently get firmer as the air pressure increases in these systems.

SUMMARY OF THE INVENTION

The present invention relates to a suspension system having a double-acting air cylinder. In one illustrative embodiment, the double acting cylinder is a single cylinder positioned between the front wheel of a motorcycle and the motorcycle main frame. In another embodiment, the double acting cylinder is a single cylinder positioned between the rear wheel of the motorcycle and the motorcycle main frame. In yet another embodiment, two or more double-acting cylinders are axially aligned and provide two or more chambers having compressed gas for controlling the suspension characteristics in a motorcycle.

The system disclosed herein could be applied to other vehicles or suspension systems, such as those found in autos and trailers. Accordingly, as referred to herein, the term “motorcycle” and the like may be substituted by “vehicle”, “auto”, “trailer”, or any other use that could incorporate the suspension system disclosed herein. Further features and advantages of the invention will be readily apparent from the specification and from the drawings.

Moreover, although the illustrated embodiments relate to a suspension system for a front wheel, it should be understood that the concepts described herein can be applied to a rear wheel suspension system with few or no modifications, and rear wheel suspension systems are within the scope of the disclosure.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates a well-known main frame10and front wheel frame12for a motorcycle14. Such a main frame10and front wheel frame12function together in a well known manner and a number of suspension systems have been proposed, designed and marketed which provide suspension functions to the front wheel frame12of such a motorcycle14. Generally, the front wheel frame12is connected to a suspension component16that absorbs forces resulting from the front wheel's movement or contact with objects during operation of the motorcycle14. A suspension component16is connected to and operates between main frame10and front wheel frame12(or in a non-illustrated embodiment, between main frame10and a rear wheel frame).

FIG. 2shows one embodiment of a suspension component16, wherein the suspension component includes a housing17having a first end19and a second end21. First end19is illustratively configured to be connected to the main frame10of the motorcycle, and second end21is illustratively configured to connect to the wheel (either front or rear) frame. In the illustrated embodiment, suspension component16comprises at least a part of the front suspension assembly of the motorcycle, and compresses and extends to adjust for inconsistencies in the road, allowing the front (or rear) tire to maintain contact with the road for better handling and braking without the rider feeling the up-and-down movement of the wheel.

FIG. 3is a view of the suspension component16ofFIG. 2, wherein the housing walls have been removed to reveal the two double-acting cylinders18,20housed within housing17. In such an embodiment, double-acting cylinders18,20are arranged coaxially along axis23and pistons25,27move axially together relative to housing17. Suspension component16is in pneumatic communication with a system22(shown inFIG. 5) that provides compressed gas to the double-acting cylinders18,20. In the illustrated embodiment, air is disclosed as the compressed gas. However, it should be understood that the use of other gases is within the scope of the invention.

Housing17of suspension component16is capable of holding pressurized air. Although the illustrated housing defines a pair of axially aligned air cylinders18,20, it is contemplated that other arrangements are possible, and within the scope of the invention. Moreover, it is possible for a single air cylinder18to be used, rather than the use of two axially aligned air cylinders. Accordingly, it should be understood that embodiments described herein that disclose two double-acting cylinders can also be configured as a single double-acting cylinder. However, the use of more than one axially aligned air cylinder, such as described herein, provides the advantage of greater resistance over a smaller stroke range.

As shown inFIGS. 3 and 4, disposed within the air cylinders18,20are a respective pair of pistons25,27, which are sealed in the cylinders so as to prevent loss of air pressure. Such pistons are positioned to reciprocate within the cylinder bores. Pistons25,27are connected via piston rod29. Furthermore, housing17has a port31formed therein for directing compressed air through the housing17into chamber33of cylinder18. As compressed air fills chamber33, piston25is urged toward cylinder baffle35. Compressed air can also be directed through channel37that is illustratively bored through the axial center of piston rod29. This compressed air is then directed through port39into chamber41, providing for simultaneous compression of chambers33,41. Opposing chambers43,45may be filled with a compressed gas or ambient air, as further disclosed below. The resulting effect is that both pistons25,27will be positioned within their respective double-acting cylinders18,20, and suspended by the compressed air in the opposing chambers33,41and chambers43,45. When pressurized air enters chambers33,41, pistons25,27are forced toward second end21of suspension component16, thereby causing piston rod29to extend. Such extension of suspension component16can also provide for raising or lowering of the entire motorcycle.

Compressed air to suspension component16is illustratively provided with a system (and variations)22such as that shown inFIG. 5. As seen inFIG. 5, system22comprises a relay24connected to a battery26(illustratively the motorcycle battery). Closing relay24permits electricity from battery26to operate an air motor or compressor28. In one embodiment, the relay24is in the same circuit as the ignition switch; therefore, the activation of the ignition switch closes relay24and permits operation of compressor28.

System22may be configured such as that shown inFIG. 5A, wherein compressor28is configured to supply compressed air to a volume chamber30. A filter32may also be incorporated into system22to filter impurities, such as particulate matter and oil. Pressure in volume chamber30is set by an operator pressing one of buttons40until the desired pressure (and ride characteristics) are achieved. A check valve36can be incorporated to retain the air in volume chamber30. Volume chamber30may be a separate chamber or may be part of the motorcycle frame, such that a frame member of the motorcycle functions as a volume chamber and could contain pressurized air.

As shown inFIG. 5, a solenoid valve38may be incorporated in system22. Solenoid38permits an operator to dump pressure from the system, thereby softening the ride and/or lowering the ride height for the operator. Furthermore, system22could be configured such that compressor28will not operate unless the ignition switch is turned to the “lights on” position.

Push buttons40can also be provided for controlling the compressed air in the double acting cylinders. Such push buttons40may be located in a position convenient to a motorcycle rider, such as near or on the handle bars. The push buttons40control the compressed gas pressure in double acting cylinders18,20by either directing additional compressed air to be added to double acting cylinders18,20or bleeding air from cylinders18,20. By varying the amount of compressed air in cylinders18,20, the ride height, ride quality, and/or spring rate of the cylinders can be modified to the user's liking or needs.

Another embodiment of the invention is shown inFIG. 5B. In such an embodiment, pressure in opposing chamber43,45(visible inFIG. 4) can be controlled simply via a check valve42, shown inFIG. 5B. Such a check valve42would allow for the intake of ambient air into opposing chambers43,45when the system is not energized (i.e. chambers33,41are not energized with compressed air). For example, during the initial installation of the check valve, the initial suspension travel (extension) will suction air through check valve42into chamber45, and the check valve will seat. This air is now trapped and will act as an air spring and biasing element. When the system is later energized, check valve42would seal, and opposing chamber45would provide an opposing bias as chambers33,41are further energized.

Importantly, for all embodiments disclosed herein, it is possible (and sometimes preferable) for a check valve to be installed on both chambers43,45to trap air. Consequently, either or both chambers43,45could be charged with pressurized air depending on the use or desired suspension qualities. For example, when a firmer ride is desired, both chambers43,45can be charged with compressed gas or air.

In yet another alternative embodiment, shown inFIG. 5C, chambers43,45may be pre-pressurized to a pre-selected level prior to delivery to the consumer. A desirable pre-selected pressurization level has been determined to be approximately three pounds-per-square-inch, but any pressure above zero psi and below 10 psi is contemplated to be within the scope of the invention.

In a further embodiment illustrated inFIG. 5D, pressurized air can be supplied to the opposing chambers43,45at a secondary pressure to offset the primary pressure in chambers33,41. Such a secondary air pressure is generated by a biasing regulator44. One example of a biasing regulator44is a Type 200 Precision Air Relay manufactured by ControlAir Inc.; more information can be obtained at www.controlair.com. The biasing regulator44is supplied with pressurized air from system22and may be preset by the system manufacturer, motorcycle manufacturer or in the alternative, adjusted for ride characteristics by the operator.

In the embodiment illustrated inFIG. 5D, a biasing regulator44is connected to chambers18,20, and is configured to deliver a secondary pressure at a pressure relative to that of chambers18,20to opposing chambers43,45. Such a configuration is provided in part to offset the pressure in chambers33,41. This pressure in chambers33,41controls the rebound of the suspension component, and of the front or rear end of the motorcycle as a whole.

Biasing regulator44further provides a counterbalance to the air spring effect on an opposite side (i.e. chambers43,45) of the piston as that of the main air suspension pressure (chambers33,41). The biasing regulator maintains a ratio or proportional counterforce to the air spring unloaded setting, and thus, provides the rebound control in a manner which tracks any changes in the main air spring pressure. Air functions as an ideal spring due to the fact that the spring rate is progressive during compression in contrast to most springs, which have a linear fixed compression rate.

In the disclosed embodiment, first end19(and second end21), shown inFIGS. 2-4, may be fitted with a self-lubricating bearing material on the bearing contact surface50that permits extended function. Furthermore, the tolerances for first and second ends19,21may be such that the suspension component18may be installed on a variety of motorcycles and even on frames having slight offsets or imperfections. Moreover, due to the small size of suspension component16(less than diameter of a standard monoshock 3.25″ and the same overall length), the presently disclosed system may be substituted for nearly any existing suspension component.