Patent Application
20170057315
This invention relates to an on-board power unit for ride-height adjustment of a motorcycle. The invention has particular application to certain of those Harley-Davidson motorcycles distinguished by the name “Softail”, although it may have application to motorcycles of other manufacturers that emulate the form of the Harley-Davidson “Softail” form of motorcycle frame.
There has been a long history of development for the form of motorcycle frame that characterised the modern Harley-Davidson “Softail” motorcycle. U.S. Pat. No. 1,266,800 to William S Harley, assignor to Harley-Davidson Motor Company, proposed an early form of a suspension system acting between the rear end of a motorcycle main frame and a rear fork frame on which the rear, drive wheel is mounted. The forward, lower corner of the rear frame is hinged to the main frame to enable the trailing end of the rear frame and a wheel carried at that trailing end to rise or fall relative to the main frame. The forward, upper corner of the rear frame carries a forwardly projecting plunger able to advance longitudinally within the reach bar of the main frame, against the action of a helical expansion spring, to enable the trailing end of the rear frame and the wheel to rise, while the trailing end of the frame and the wheel are able to fall against the reaction of leaf springs that act between each of the front and rear frames so the expansion spring and the leaf springs counteract each other. Apart from the provision of the helical spring, this early proposal is similar to the alternative arrangements for bicycles shown in U.S. Pat. Nos. 644,787 and 644,957, both to Williams.
Like the '800 patent to Harley, U.S. Pat. No. 1,272,399 to Douglas shows a suspension acting between the rear end of a main frame and a rear fork frame hinged at a forward, lower corner to the main frame. However, the suspension differs and the overall arrangement seems to be envisaged as more for a bicycle than for a motorcycle. A linkage system of a toggle link and a connecting link joins the forward, upper end of the rear frame to the main frame, while coil springs able to act in both tension and compression extend between the main frame and the toggle links.
U.S. Pat. No. 1,576,216 to Philips shows a further arrangement for a forked, rear frame hinged at a lower forward corner to the main frame, but with the suspension acting between the main and rear frames. The suspension comprises a leaf spring that extends from the rear frame to the front fork of the main frame, within a downwardly open top longitudinal channel of the main frame in which the leaf spring is secured.
U.S. Pat. No. 3,877,539 to Tilkens, assignor to Yamaha Hatsudoki KK, proposes a motorcycle shock absorbing rear fork suspension similar to that of the '800 patent to Harley. However, the Tilkens suspension utilises a helical spring to counteract with a telescopic device within and along the tank rail forming the reach rail of the main frame.
U.S. Pat. Nos. 4,022,484 and 4,087,109, both to William F Davis, are directed to overcoming what was seen as a disadvantage of previous arrangements, such as those of the '800 patent to Harley, the '399 patent to Douglas, the '216 patent to Phillips and the '539 patent to Tilkens. The disadvantage was the loss of the streamline appearance of the original rigid unitary frame that converged from a high, front end to the rear wheel axle, despite that being the appearance of motorcycles that were without rear wheel suspension. The proposal of Davis patents was to revert to the streamline appearance for the overall combination of a main frame and a rear fork frame, but also to raise the hinge connection between these frames to a level somewhat midway between the lower and upper forward corners of the rear frame, and to provide a spring/shock absorber device between the main and rear frames. In the earlier arrangement of the '484 patent, that device was coupled to the upper forward corner of the rear frame and a mid-height location at the rear of the main frame. In the '109 patent, the device was coupled to each of the upper forward corner of the rear frame and an upper rear corner of the main frame.
U.S. Pat. No. 4,568,101 to Bleustein et al., assignors to Harley-Davidson Motor Co., Inc., provides an automatic suspension system for vehicle, such as a motorcycle, that enables adjustment of the front and rear suspension systems. The automatic system is not of overall relevance to the present consideration as, in the context of motorcycles, it essentially relates to a single frame in relation to which the front and rear suspension systems are mounted. However, the '101 patent has an informative description of motorcycle height criteria.
With the advent of the Harley-Davidson “Softail”, there then followed a number of proposals for modification of its performance. One of the first of these proposals was that of U.S. Pat. No. 5,348,112 to Vaillancourt, assignor to Works Performance Products, Inc., which proposes a motorcycle height adjuster indicated as suitable for suspensions of the kind distinguished by the name “Softail” popularised by Harley-Davidson Motor Co. Inc. The proposal is indicated as enabling “on-the-go” adjustment from the rider's position. The height adjuster has a manually operable double-acting control unit by which hydraulic fluid is supplied to or withdrawn from a spring biased piston and cylinder actuator, via an hydraulic line extending between the control unit and the actuator. The control unit can be positioned at a convenient location on a motorcycle, with the actuator having its cylinder and a rod of the piston coupled to a respective one of the main frame and rear fork frame of the motorcycle. The actuator may be positioned in a parallel relationship to a similarly coupled shock absorber such that, as the actuator is extended, a spring of the shock absorber is compressed
U.S. Pat. No. 5,487,443 to Thurm proposes removal of the system of a swing axle tube and parallel shock absorbers of a Harley-Davidson “Softail” motorcycle, and replacement of the system by a torsion bar having a longitudinal axis coincident with the pivot axis on which the rear fork frame is adjustable relative to the main frame.
U.S. Pat. No. 6,003,628 to Jurrens et al. suggests needs for maintaining the aesthetic appearance of the “Softail” frame while improving ride and comfort and for enabling the rear to be raises or lowered when desired. To fulfil these needs there is provided an arrangement in which the parallel shock absorbers of a Harley-Davidson “Softail” motorcycle are replaced by air bags operating through a housing of two relatively slidable housing parts. However for a motorcycle suited for use over rough terrain, the arrangement of the '628 patent is indicated as needing to be of an embodiment also including an in-line shock absorber.
U.S. Pat. No. 6,123,165 to Smith, assignor to Chrome Specialties, Inc., provides a swing arm adjuster for a “Softail” motorcycle frame having the usual dampers or shock absorbers. The adjuster has a mounting bracket for a damper that is connected to a threaded receiver and an adjuster plate that is connected to the swing arm of the rear frame, with a threaded nut through the adjuster bracket. The adjuster is able to adjust the connection to the damper and also the steady state position of the rear frame relative the main frame at a selected ride height.
U.S. Pat. No. 6,131,494 to Quenneville describes the inter-relationship between the rear fork frame and the main frame of a Harley-Davidson motorcycle, and shows in
U.S. Pat. No. 6,142,498 also to Smith, assignor to Chrome Specialties, Inc., identifies the '484 patent to Davis as showing a typical frame for Harley-Davidson “Softail” motorcycles, at least through to about December 1998. The '498 patent utilises the same basic front and rear frames as the '165 patent, but specifies a narrower spacing between the upright frame members at the rear of the main frame and the forward end of the rear fork frame such that the drive belt, chain or other drive member can be outside the upright members, avoiding the need to remove the rear frame for replacing the drive.
U.S. Pat. No. 6,193,005 to Jurrens relates to the same arrangement as provided in the '628 patent to Jurrens et al., but also adds an alternative form of that arrangement. The alternative form provides more positive guidance for longitudinal movement between the relatively slidable housing parts, with incorporation of resilient stops. Also, hydraulic or pneumatic damping of travel of the air bags.
Successful, but abandoned, US patent application 2002/0066611 by Lane et al., parallels the '443 patent to Thurm, the '628 patent to Jurrens et al. and the '005 patent to Jurrens, in pointing to limitations in the ride comfort provided by the Harley-Davidson “Softail”. The approach of the '628 patent is criticised, in part because the air-bag is difficult to retrofit and more expensive. However, in addition to an alternative engine mounting arrangement, Lane et al. then proceeds to propose significant changes to detail of the “Softail” frame structure that amounts to an alternative design, as distinct from something enabling a retrofit, to enable installation of an air suspension system comprising an air bag between the rear of the front frame and the rear frame.
U.S. Pat. No. 6,357,546 to Crosby, Jr., points to limitations with the air-bag arrangement of the '628 patent to Jurrens et al., and proposes an alternative to the air-bag arrangement of the '661 patent application by Lane et al.
U.S. Pat. No. 6,905,126 to Jurrens adapts an air bag suspension for “Softail” motorcycles for motorcycles of other types, such as the Harley-Davidson “FL” models. As in proposals for the “Softail”, the original pair of hydraulic shock absorbers, each mounted between a respective fender strut and a respective swing arm, are replaced by air bags. An on-board compressor and a solenoid co-operate through an air distribution system to supply air to the air bags, with the compressor and solenoid selectively operable electrically by three-position a switch
U.S. Pat. Nos. 7,798,295 and 8,307,963, each to Jurrens and relating to the same proposal, restate the discussion in the '433 patent to Thurm on the constraints inherent in the “Softail” motorcycle frame system. The common proposal of the patents is an air bag suspension device that, in at least one form, incorporates and is co-axial with an hydraulic piston and cylinder assembly.
U.S. Pat. No. 8,403,092 to Trethewey proposes a further development along the lines of the '546 patent to Crosby, Jr.
The extensive work reflected in each of the '628; '005; '126; '295 and '963 U.S. Pat. Nos. to Jurrens has resulted in the “Softail” air suspension kits for pre- and post-2000 Harley-Davidson motorcycles marketed by Legend Air Suspensions, Inc. of Sturgis, S.D.
The present invention seeks to provide an alternative for achieving ride-height adjustment for motorcycles that have or emulate the form of the certain of the Harley-Davidson motorcycles distinguished by the name “Softail”, including those of manufacturers other than Harley-Davidson. The invention, in particular is directed to enabling such adjustment for post-1999 Harley-Davidson “Softail” motorcycles.
This invention relates to an on-board power unit for ride-height adjustment of a motorcycle. The invention has application to certain of those Harley-Davidson motorcycles distinguished by the name “Softail” and, in particular, those “Softail” motorcycles manufactured in the post-1999 era. However, the invention may have application to motorcycles of other manufacturers that emulate the form in that era of the Harley-Davidson “Softail” form of motorcycle frame and rear suspension. The motorcycles in question (herein collectively referred as being of the “Softail” type of motorcycle) have a frame that includes a main frame and a rear frame that is mounted on the trailing end of the main frame and on which a rear, driven wheel is attached. The rear frame is hinged to the main frame so as to be able to rise or fall on a transverse pivot axis under the control of a rear suspension comprising a shock absorber suspension assembly acting substantially horizontally between the trailing end of a motorcycle main frame and the rear frame. The suspension assembly comprises a laterally spaced, parallel pair of hydraulically dampened shock absorbers.
The parallel pair of laterally spaced shock absorbers of the suspension assembly of the “Softail” type of motorcycle each have a trailing end pivotally connected to the lower front corner of the rear frame. Each shock absorber extends from the rear frame, across a lower transverse member secured to the rear end of each of a lower member along each side of the main frame, to a connection between the leading end of the shock absorber and a transverse bracket connecting the lower side members of the main frame. Each shock absorber has a cylindrical housing containing an hydraulically dampened piston and cylinder arrangement, with a piston rod projecting through an adjuster plate secured in the leading end of the housing to a connection, via a threaded spindle comprising an extension referred as a stub shaft, to the transverse bracket of the main frame. The trailing end of the cylinder projects through the trailing end of the housing and is pivotally connected to a lower transverse member secured to the forward end of each of a lower member along each side of the rear frame. Each shock absorber also includes a helical spring mounted around the cylinder of the piston and cylinder arrangement and contained between an annular retainer fixed around the leading end of the cylinder and an annular stop located around the trailing end of the cylinder and fixed to an annular flange at the trailing end of the housing. The arrangement is the reverse of that usual with shock absorbers in that the shock absorbers expand or contract as the rear frame pivots up or down, respectively, to cause compression or expansion of the spring, with spring recovery dampened by the piston and cylinder arrangement.
The shock absorbers of the “Softail” type of motorcycle are positioned below the seat for the rider of the motorcycle and are substantially concealed by a cover under the transmission. While the shock absorbers are functionally limited due to their positioning, this is a design feature intentionally adopted to capture the aesthetic appearance of the downwardly and rearward tapering lines of earlier rigid models that were without rear shock absorbers.
In the section of this specification headed “Context of the Invention” and in the disclosure following section on the power unit of the invention, both as described and claimed in this specification, terms indicating direction and orientation, such as leading, trailing, transverse, lateral, forward and rearward, and their grammatical variants, are to be understood as used relative to a “Softail” type of motorcycle and its forward travel in normal use.
According to the invention, there is provided an on-board mountable power unit for ride-height adjustment of a “Softail” type of motorcycle. The unit includes a pair of hydraulic actuators, each adapted to be mounted on the forward end of the rod of a piston and cylinder arrangement of a respective shock absorber of the rear suspension assembly of the “Softail” type of motorcycle, after removal of the stub shaft extension of each rod. Each of the actuators is in the form of an hydraulic actuator ram, and has a housing that has longitudinally spaced forward and trailing ends and that defines a chamber containing a piston movable between those ends. The piston has an elongate piston-rod that projects from the trailing end of the housing, through an annular end plate fitted in the trailing end of the housing, with the piston-rod having a trailing end adapted for engagement with the forward end of the rod of the piston and cylinder arrangement of the respective shock absorber. At the forward end, the housing has a forward extension with a forward end of the extension engageable with the transverse bracket connecting the lower side members of the main frame of the motorcycle. That is, each actuator is able to connect the rod of the piston and cylinder arrangement of a respective shock absorber of the motorcycle to the transverse bracket of the main frame of the motorcycle, with this connection similar to that otherwise provided by the stub shaft extensions of the shock absorbers in the usual mounting arrangement for the rear shock absorbers of a “Softail” type of motorcycle. However, each of the shock absorbers needs first to be removed from their mountings on a “Softail” type of motorcycle and, after the stub shaft extensions are removed, each of the actuators is mounted on a respective shock absorber by the piston-rod of the actuator being threaded onto the rod of the piston and cylinder arrangement of the shock absorber, and the shock absorbers then are re-installed in an assembly including the actuators.
The housing of each actuator has a port through which pressurised hydraulic fluid can be charged to the chamber of the housing at a trailing side of the piston. The arrangement is such that hydraulic fluid can be pumped into or from the chamber to drive the piston to or towards a required or selected one of the leading and trailing ends of the chamber to attain a desired position for the piston in the chamber. Thus, with the power unit installed on a “Softail” type of motorcycle, the rod of the piston of the piston and cylinder arrangement of the shock absorber of the motorcycle can be drawn to a required position. Accordingly, the actuators are operable to adjust the shock absorbers of a “Softail” type of motorcycle to attain a required ride height, with the ride height being able to be varied, as required by a rider of the motorcycle, over a range preferably limited only be the physical constraints inherent in the hinged connection between the main and rear frames of such motorcycles. That is, the housing of each actuator is able to have a chamber enabling the piston to be movable between trailing and leading extremes that do not limit that range.
The stroke of the piston of each of the actuators in a power unit of the invention, for the typical stroke of the piston and cylinder of the shock absorber for a Harley Davidson “Softail” motorcycle, may be at least 20 mm, preferably at least 21 mm, such as 22 mm. The chamber of the housing in which the piston is movable may have a diameter that is greater than the stroke of the piston, with a suitable diameter ranging up to about 45 mm. However, the diameter may range from about 38 mm to about 42 mm. As will be appreciated, the actuator is very small relative to the shock absorber, and also in relation to alternative arrangements proposed for the “Softail” type of motorcycles although, as detailed later in this disclosure, the actuators are part of a power unit that provides new useful benefits for riders of the “Softail” type of motorcycles, in particular in relation to ride height adjustment.
In each actuator, the axial length of the housing between the leading and trailing ends and the stroke of each piston within the housing are such that, with the actuators installed on a “Softail” type of motorcycle, the actuators are able to position the shock absorber at or between first and second extreme positions spaced by the stroke of the actuator pistons. The positioning results from appropriate flow of hydraulic fluid to or from the chamber of each actuator to adjust the respective piston and, hence, the extent to which the piston-rod of each actuator projects from its housing. In the first of the extreme positions the adjuster plate at the leading end of the shock absorber housing is closely adjacent to the end plate at the trailing end of the housing of the actuator, while in the second position the adjuster plate and the end plate are axially spaced by substantially the stroke of the actuator pistons. In the first position the leading end of the piston rod of each of the shock absorbers preferably is received within the inner periphery of the end plate of the respective actuator housing, while the trailing end of the piston-rod of each actuator remains within the inner periphery of the adjuster plate of the respective shock absorber throughout positioning of the shock absorbers. With the piston of each actuator in an intermediate position between the first and second extremes, the shock absorbers are operable in response to variation to operating loadings.
The forward extension of each actuator of the power unit of the invention is short relative to the removed stub shaft extension, due to space to be occupied by the actuator housing when the power unit is installed in a motorcycle. In the Harley Davidson “Softail” motorcycles each stub shaft extension passes in turn through a bushing and a first cup washer with a fitted grommet before passing, from the trailing side, through a hole in an upright flange of the transverse bracket by which the lower side members of the main frame are connected, and the arrangement then is secured at the leading side of the flange by a second cup washer with a fitted grommet and a retaining nut threaded onto the stub shaft extension. However, with the relatively shorter forward extension on each actuator of the power unit, there is no space for such a bushing and first cup washer. Instead, a first grommet is provided on the forward extension of each actuator, against the outer surface of the leading end of the housing, with the forward extension then passing through the upright flange and being retained by a cup washer with a second grommet, and a retaining nut threaded onto the leading end of the forward extension.
In each of the actuators the piston-rod and the forward extension preferably are co-axial with each other and with the chamber in which the piston is movable, with the chamber of cylindrical form. The piston-rod may be an annular sleeve having a bore throughout the length of the sleeve. As indicated above, the trailing end of the forward extension is internally screw threaded for engagement with the leading end of the rod of the shock absorber of the motor cycle although, with a sleeve form of piston-rod, the internal threading need only be at the trailing end of the bore. Where the piston-rod is a sleeve with a through bore, the actuator may include a shaft that projects from the wall at the leading end of the housing, co-axially within the chamber and into the bore of the sleeve. Over a main part of its length, the shaft may be a neat sliding fit in at least a leading end part of the bore of the sleeve. Preferably, the shaft has a slightly larger trailing end part that is a neat sliding fit in a main part of the length of the bore of the sleeve, such that at a rearward limit to the movement of the piston in the housing, a forwardly facing annular surface of the shaft within the sleeve bears against a rearward facing annular surface of the sleeve.
For actuators having a shaft that projects co-axially within the chamber from the wall at the leading end of the housing, the forward extension also may be an annular sleeve having a bore extending throughout the length of the sleeve. Particularly in that event, the piston may be of annular form that fits neatly on the leading end of the piston-rod and secured, such as by provision of a round wire snap ring captured in opposed grooves, comprising a first groove around the piston-rod and a second groove in the inner periphery of the piston. Also in that event, the shaft may extend from within the bore of the forward extension, while it may be retained within that bore, such as by screw-threaded engagement in the bore. The shaft may have a leading end that is at, adjacent to or close to the leading end of the forward extension, such as to be accessible from the leading end of the forward extension. The arrangement may be such that, by access at that leading end, the shaft is longitudinally adjustable in the forward extension to vary, by a limited amount, the extent to which the shaft extends into the chamber. Thus where, as indicated above, the shaft and the piston-rod have oppositely facing annular surfaces that are able to abut, the rearward limit to the movement of the piston in the housing can be adjusted to a limited amount, for reasons explained later herein. However, access at the leading end of the forward extension may be, and preferably is, precluded by a safety seal.
The forward extension and the housing of the actuator, including the end wall at the leading end, preferably comprise a single-piece, unitary construction that may be produced by casting or machining of a suitable high strength metal, such as a high tensile, preferablynitrided, steel. The chamber is defined by the wall at the leading end of the housing, a peripheral wall and the annular end plate, with the end platefitted at the trailing end of the housing and the piston-rod extending through the end plate. A relatively short trailing end section of the peripheral wall accommodates the end plate. The end section has a slightly larger internal diameter than the chamber along which the piston is movable, to provide an internal shoulder of the housing against which a peripheral flange of the end wall locates. A resilient “O” ring is forced against the trailing side of the peripheral flange by a retaining circlip, to provide a static seal between the housing and the periphery of the end wall. A dynamic seal is provided between the piston-rod and an inner peripheral surface of the end plate, with this comprising an “O” ring seal located in an annular groove in the inner peripheral surface, with the seal preferably an X-section ring. A similar dynamic seal is provided between the inner periphery of the piston and the piston-rod, adjacent to the circlip that retains the piston on the piston-rod, while a further similar dynamic seal is provided between the outer periphery of the piston and the housing. The static seal, and each dynamic seal, preferably is formed of a suitable grade of a synthetic rubber, for example a Nitrile rubber such as Nitrile 70 durometer rubber. Also, the trailing face the end plate has an annular flange concentric with and closely adjacent to the piston-rod, and a wiper ring is provided between the flange and the piston-rod.
The respective port through which pressurised hydraulic fluid can be charged to the housing of each actuator communicates with an annular groove formed around the inner surface of the trailing end section of the housing on the leading side of the dynamic seal provided against the flange of the end plate. From that groove, the hydraulic fluid is able to pass to the chamber via a number of radial grooves in the internal shoulder of the housing or in an outer margin of the leading face of the end plate.
The on-board mountable power unit of the invention also includes an hydraulic power unit operable to supply pressurised hydraulic fluid to, or to enable hydraulic fluid to discharge from, the chamber of each actuator to enable adjustment of the ride height of a “Softail” type of motorcycle on which the power unit is mounted. The power includes a reservoir containing a sufficient volume of hydraulic fluid, a pump for supplying hydraulic fluid from the reservoir to the chamber of each actuator via a respective hydraulic fluid flow line and enabling a return flow of fluid to the reservoir, and an electric motor operable for driving the pump. Preferably, the power unit also includes ancillary circuitry connectable to the electric system of the motorcycle for operating and controlling the electric motor according to the requirements of the motorcycle rider.
The size, positioning and functioning of the actuators of the on-board mountable power unit are such that they can be installed and operated in substantially complete harmony with the design criteria for the “Softail” type of motorcycle. That is, the actuators do not detract from such motorcycles having the aesthetics of the rigid frame Harley Davidson motorcycles that are without rear suspension. However, the actuators provide a further benefit in that they are fully compatible with the hydraulic power unit being able to be of a preferred form in which it can be of a size and form that also can be positioned and operated in substantially complete harmony with those design criteria. Thus, in a preferred form, the reservoir, pump, hydraulic fluid flow line and electric motor of the power unit is assembled into a compact unit able to be installed and secured between the lower side members of the main frame, adjacent to the leading side of the transverse bracket that connects those side members. For this, the power unit preferably is housed in a suitable frame structure mountable in relation to the lower side members of the main frame.
In one convenient arrangement, the power unit is secured by being housed in a frame structure having an under-tray assembly, designed to be positioned under the lower side members of the main frame, and a mounting bracket assembly able to be located between those side members and secured to the under-tray assembly. The bracket assembly may consist of a leading mounting bracket and a trailing mounting bracket each of which can be connected to the under-tray such as by screw-threaded bolts. The trailing mounting bracket preferably is shaped to fit against the leading surface of the transverse bracket that connects between those lower side members, with each end of the trailing bracket shaped to fit around the retaining nut threaded onto the leading end of the forward extension of each actuator. The trailing bracket may be held in such position by having hooks that engage over the upper edge of the upright flange of the transverse bracket, with the hooks being held in engagement with that edge by threaded engagement between the trailing mounting bracket and the under-tray assembly located below the lower side members. The leading mounting bracket is spaced forwardly from the trailing mounting bracket and preferably is held by having respective end portions each engageable around a respective lower side member.
The power unit may have a compact electric motor, conveniently a 12 volt DC motor, such as one operable on a supply current of about 10 amps. The pump also may be of a compact form, and preferably comprises a bi-directional, gear type of pressure pump provided with a pressure relief valve. The reservoir may define a chamber in direct communication with an intake port of the pump. The chamber preferably has a capacity enabling it to accommodate the volume of hydraulic fluid able to be pumped from the actuators, such that the reservoir remains substantially unpressurised. In one convenient arrangement, the reservoir is in the form of a resilient, synthetic rubber housing having a mouth bordered by a peripheral out-turned flange by which the housing can be clamped against a mounting block in relation to which the motor and pump also are secured. The arrangement may be such that the reservoir communicates with the intake port of the pump through the mounting block, with the pump having an outlet port that is in communication through the mounting block with two connectors for a respective hydraulic flow line communicating with the chamber of each actuator.
With the actuators installed on a “Softail” type of motorcycle and operated to position the shock absorbers in or close to the first of the two extremes discussed, access to the adjuster plate of each shock absorber is limited. The adjuster plate is rotatable to enable the pre-loading of the shock absorbers to be adjusted, with this requiring fitting of a special adjuster tool, similar to that disclosed in the above-mentioned U.S. '494 patent to Quenneville, to locate prongs or the like in circumferentially spaced holes in the outer face of the adjuster plate. With the shock absorbers in or close to the first extreme position, the prongs are not able to be located as required due to the holes being positioned radially inwardly from the outer circumference of the adjuster plate and opposed by the actuator housing. The power unit of the invention therefore needs to be operated to move the adjuster plate to the second extreme position, although an alternative is to use the power unit in conjunction with a modified form of adjuster plate to be substituted for that present as original equipment in the shock absorbers of the “Softail” type of motorcycle. Rather than having holes located radially inwardly from the outer periphery as in the adjuster plate of those shock absorbers, one form of the modified adjuster plate has circumferentially spaced recesses formed in, and preferably opening to the outer periphery of, the modified plate, with the recesses also opening to the leading surface of the plate and having a form suited for co-operation with prongs or the like of a suitably, corresponding form of adjuster tool. The recesses may, for example be of substantially circular form as viewed from that leading surface, but opening to the outer periphery of the plate. The modified adjuster plate enables access by the corresponding form of tool, due to the recesses being accessible radially outwardly of the actuator housing.
In an alternative form, a modified adjuster plate for each shock absorber replaces the original equipment adjuster plate and is adapted to be used in combination with an internal collar device that is adapted to be fitted around the leading end of the cylinder of the piston and cylinder arrangement of the shock absorber. The modified adjuster plate has a central bore sized to enable the modified plate to be secured as a press fit on the trailing end of the piston-rod of the actuator, with the modified plate then fitted in the leading end of the shock absorber housing in a similar manner to the originally supplied replaced adjuster plate. The collar device fits around the cylinder, preferably by being received from the trailing end of the piston and cylinder arrangement, and secured on the leading end of the cylinder. The collar has inner and outer concentric parts that are coupled together by a screw-threaded engagement so that, with the inner part axially fixed on the cylinder, the outer part is able to rotate and move axially relative to the inner part. The inner part may be fixed on the cylinder in a number of suitable ways, although it preferably is releasably fixed on the cylinder. In one convenient form, the inner part has a bore through which the cylinder is received, with the bore tapered so as to as to have a slightly frusto-conical form, with half angle of about 1 or 2 degrees, that increases slightly in diameter towards the leading end. The inner part can be fixed on the cylinder by being forced axially over a wire snap ring located in a peripheral groove in the outer surface of the cylinder so the tapered bore surface bears against and compresses the snap ring into the groove. With the inner part fixed on the leading end of the cylinder of the piston and cylinder of a shock absorber, the outer part is able to rotate on the inner part so and move axially in one of opposite axial directions, depending on the direction of the rotation.
With the modified adjuster plate used with the two-part collar device, the outer part of the collar device replaces the annular retainer of the original equipment shock absorber. As with that retainer, the collar device enables variation in the degree of pre-load applied to the spring of the shock absorber, with the pre-load varied by rotation and axial adjustment of the outer part of the collar device relative to the inner part. That rotation is able to be achieved by inserting the of prongs of a suitable tool through selected openings spaced around the outer periphery of the modified adjuster plate, and engaging the prongs with formations of the outer part of the collar device. The modified adjuster may, for example, have three, four or even more uniformly spaced openings through at least two selected openings respective prongs are able to be inserted to enable the tool to apply required torque for rotating the modified adjuster plate and the outer part of the collar device. The outer part may have a circumferential array of longitudinally extending openings or keyways in selected ones of which the prongs are locatable for rotation of the outer part by the tool. In one convenient arrangement, the openings or keyways are defined by the outer periphery of the outer part being defined by a circumferential array of alternating ribs and grooves, with the grooves being U-shaped in cross-section.
In order that the invention may more readily be understood, description now is directed to the accompanying drawings, in which:
The frame structure 10 shown in
The lower side members 16 and the upper side members 18 are secured in a relatively rigid laterally spaced relationship by respective transverse connecting members. The connecting members include a lower transverse member 22 secured to the rear end of each lower side member 16, an upper transverse frame member 24 secured to the rear end of each upper side member 18 and, at each side of the motorcycle, an upright strut 26 that joins the rear ends of the respective lower member 16 and upper member 18. Each of the struts 26 is forwardly curved between the rear ends of the respective members 16 and 18. The lower side members 16 also are connected by a transverse bracket 28 that is spaced a short distance forwardly of the lower transverse member 22.
For each side of the motorcycle, the rear frame 14 has a respective lower side member 30 and a respective upper side member 32, with members 30 and 32 at each side of frame 14 converging to the trailing end, away from the main frame, to form a rear wheel axle mount 34. The lower and upper side members 30 and 32 of each side are secured in a relatively rigid laterally spaced relationship by connecting members that include a lower transverse member 36 secured to the forward end of each lower side member 30 and having a short, transverse tubular mount 38 centrally secured along the leading side of member 36; an upper transverse member 40 secured to the forward end of each upper member 32; and, at each side of the motorcycle, an upright strut 42 that joins the leading ends of the lower and upper members 30 and 32 and that is forwardly curved between the forward ends of the lower and upper side members 30 and 32.
The curved struts 26 of the main frame 12 and the curved struts 42 of the rear frame 14 are complementary and inter-fit, with each strut 42 of the rear frame 14 laterally adjacent to an inner surface of a respective strut 26 of the main frame 12. The arrangement is such that the struts 42 are between the struts 26, with adjacent respective struts 26 and 42 hinged together at a mid-height location of the struts 26 and 42, by aligned bushings (not shown) that are journalled in aligned bosses 43 and define a transverse pivot axis “X”(depicted in
The suspension assembly 44 comprises a parallel pair of laterally spaced, substantially horizontally extending shock absorbers 46, of which one is shown in the exploded view of
extension 68 is internally threaded for threaded engagement with external treading on the leading end of piston rod 62. The trailing end of the cylinder 60, on which the connector 48 is mounted, projects through the trailing end of the housing 54 and, as indicated, is pivotally connected via the mount 38, to the lower transverse member 36 of the rear frame 14. Each shock absorber 46 also includes a helical spring 70 (of which only respective ends are shown in
As previously indicated, each shock absorber 46 has a connector 48 at its trailing end by which it is attached to the mount 38 of the rear frame 14. The leading end of each shock absorber 46 is connected to the main frame. For this, each stub shaft extension 68 projects through a respective opening 28a in an upstanding flange 28b of the bracket 28. On the trailing side of flange 28b, the stub shaft extension 68 extends through a bushing 78 and, as seen in
The shock absorbers 46 of a “Softail” type of motorcycle are positioned below the seat for the rider of the motorcycle and are substantially concealed by a cover under the transmission. In that location, the shock absorbers 46 and can be substantially concealed by a cover under the transmission, but their location enables the motorcycle, despite having rear suspension, to capture the aesthetic appearance of the downwardly and rearward tapering lines of earlier rigid models that were without rear shock absorbers.
The views of
The available pivotal movement of the rear frame 14 on the transverse axis “X”, under the control of the rear shock absorbers 46, is illustrated in
Respective exploded perspective views of components of an on-board mountable power unit system 108 of the invention are shown in
The system 108, as seen in
The hydraulic power unit 112, as shown in
In a preferred form, the hydraulic power unit 112 has a 12V DC electric motor 126 operating on a 10 A current. The motor 126 drives pump 122 with the pump 122 preferably comprising a bi-directional gear type of pump having a pressure relief valve 136 shown in the hydraulic circuit 138
The motor 126 conveniently is able to be powered through a circuit including the battery B and the rear light harness H of the motorcycle, with the circuit including a 15A fuse 140, accommodated in fuse socket 141, and a fusible link 142, as shown in
As depicted in
As shown in
As shown in
The housing 166 of each actuator 110 has a port 176 through which pressurised hydraulic fluid can be charged to or discharged from the chamber 168 at a trailing side of the piston 170. Hydraulic fluid can be pumped into or from the chamber 168 to drive the piston 170 to or towards the leading or trailing end of the chamber 168, respectively, to attain a desired position for the piston 170 in the chamber 168. Thus, with the power unit system 108 installed on a “Softail” type of motorcycle, the rod 68 of the piston of the piston and cylinder arrangement 56 of the shock absorber 46 of the motorcycle can be drawn to a required position. Accordingly, the actuators 110 are operable to adjust the shock absorbers 46 of a “Softail” type of motorcycle to attain a required ride height, with the ride height being able to be varied, as required by a rider of the motorcycle, over a range preferably limited only be the physical constraints inherent in the hinged connection between the main and rear frames of such motorcycles. The chamber 168 of housing 166 of each actuator 110 has a size enabling the piston 170 to move between trailing and leading extremes that do not limit that range.
The stroke of the piston 170 of each of the actuators 110, for the typical stroke of the piston and cylinder of the shock absorber for a Harley Davidson “Softail” motorcycle, may be at least 20 mm, preferably at least 21 mm, such as 22 mm. The chamber 168 of the housing 166 in which the piston 170 is movable may have a diameter that is greater the stroke of the piston, with a suitable diameter ranging up to about 45 mm. However, the diameter preferably ranges from about 38 mm to about 42 mm. As will be appreciated, the actuators 110 are very small relative to the shock absorbers 46, as realistically illustrated in
The forward extension 174 of each actuator 110 is short relative to the removed stub shaft extension 68, due to the limited available space to be occupied by the actuator housing 166 when the power unit system 108 is installed on a motorcycle. In contrast to the Harley Davidson arrangement utilising stub shaft extensions 68, the arrangement of the invention saves some space by utilising a first grommet 178 provided around the forward extension 174 of each actuator 110, directly against the outer surface of the end wall 166c at the leading end of the housing 166. The forward extension 174 then is able to pass through the opening 28a in the upright flange 28b, to enable the flange 28b to be gripped closely adjacent to the wall 166c between that grommet 178 and a second grommet 180 housed in a cup washer 182 having a second grommet 178a and provision of a retaining nut 182 threaded onto the leading end of the forward extension 174.
In the actuators 110 the piston-rod 172 and the forward extension 174 are co-axial with each other and with the chamber 168 in which the piston 170 is movable, with the chamber 168 of cylindrical form. The piston-rod 172 is in the form of an annular sleeve having a bore 172c throughout the length of the sleeve. As indicated above, the trailing end of the piston-rod 172 is internally screw threaded for engagement with the leading end of the rod of the shock absorber of the motor cycle although, with a sleeve form of piston-rod 172, the internal threading need only be at the trailing end 172b of the bore 172c. The actuator 110 includes a shaft 184 that projects from the wall 166c at the leading end of the housing 166, co-axially within the chamber 168 and into the bore 172c of the piston-rod 172. Over a main part of its length, the shaft 184 is a neat sliding fit in at least a leading end part of the bore 172c. The shaft 184 has a slightly larger trailing end part 184a that is a neat sliding fit in a main part of the length of the bore 172c of the piston rod 172, such that at a rearward limit to the movement of the piston 170 in the housing 166, a forwardly facing annular surface of the shaft 184 within the sleeve comprising piston-rod 172 bears against a rearward facing annular surface adjacent to the leading end of the bore 172c.
In addition to each actuator 110 having the shaft 184, the forward extension 174 also is an annular sleeve defining a bore 174a extending throughout its length. Also, the piston 170 is of an annular form that fits neatly on the leading end of the piston-rod 172 where it is secured by a round wire snap ring 186 captured in opposed grooves, around the piston-rod 172 and in the inner periphery of the piston 170. Also, the shaft 184 extends from within the bore 174a of the forward extension 174 and is retained within bore 174a, by screw-threaded engagement, in the bore 174a, between the forward extension 174 and the shaft 184. The shaft 184 has a leading end that is at, adjacent or close to the leading end of the forward extension 174, such as to be accessible from the leading end of the forward extension. The arrangement may be such that, by access to bore 174a at that leading end, the shaft 184 is longitudinally adjustable in the forward extension 174 to vary, by a limited amount, the extent to which the shaft 184 extends into the chamber 168. Thus, the axial location at which the oppositely facing annular surfaces of the shaft 184 and the piston-rod 172 are able to abut and, hence, the rearward limit to the movement of the piston 170 in the housing 166, can be adjusted to a limited amount. However, access at the leading end of the forward extension 174 may be, and preferably is, precluded by a safety seal (not shown).
The forward extension 174 and the housing 166 of each actuator 110, including the end wall 166c, preferably comprise a single-piece, unitary construction produced by casting or machining of a suitable high strength metal, such as a high tensile steel that preferably is nitrided. The chamber 168 is defined by the wall 166c at the leading end of the housing 166, a peripheral wall 166c of housing 166 and the annular end plate 167 that is fitted at the trailing end of the housing 166 and through which the piston-rod 172 extends. A relatively short trailing end section 166d of the peripheral wall accommodates the end plate 167. The end section 166d has a slightly larger internal diameter than the chamber 168 along which the piston 170 is movable, to provide an internal shoulder of the housing against which a peripheral flange 167a of the end plate 167 locates. A resilient “O” ring 188 is forced against the trailing side of the peripheral flange 167a by a retaining circlip 190, to provide a static seal between the housing 166 and the periphery of the end plate 167. A dynamic seal 192 is provided between the piston-rod 172 and an inner peripheral surface of the end plate 167 by an “O” ring seal located in an annular groove in the inner peripheral surface, with the seal preferably an X-section ring. A similar dynamic seal 192a is provided between the inner periphery of the piston 170 and the piston-rod 172, adjacent to the snap ring 186 that retains the piston 170 on the piston-rod 172, while a further similar dynamic seal 192b is provided between the outer periphery of the piston 170 and the housing 166. The static seal, and each dynamic seal, preferably is formed of a suitable grade of a synthetic rubber, for example a Nitrile rubber such as Nitrile 70 durometer rubber. Also, the trailing face the end plate 167 has an annular flange 167b, concentric with and closely adjacent to the piston-rod 172, and a wiper ring 194 is provided between the flange and the piston-rod.
The respective port 176 through which pressurised hydraulic fluid can be charged to or discharged from the chamber 168 in each housing 166 of each actuator 110 communicates with an annular groove 195 formed around the inner surface of the trailing end section 166d of the housing on the leading side of the dynamic seal 188 provided against the flange of the end plate. From that groove, the hydraulic fluid is able to pass to the chamber via a number of radial grooves 195a in the internal shoulder of the housing or in an outer margin of the leading face of the end plate.
With the actuators 110 installed on a “Softail” type of motorcycle, access to the adjuster plate to enable the pre-loading of the shock absorbers to be adjusted can be restricted, as detailed above. As a consequence, it can be beneficial to adopt a modified form of adjuster plate arrangement such as the two-part form shown in
With the arrangement of the modified adjuster plate 90 and the two-part collar device 91, the outer part 93 of the collar device replaces the annular retainer 86 of the original equipment shock absorber 46. As with that retainer 86, the collar device 91 enables variation in the degree of pre-load applied to the spring 70 of the shock absorber 46, with the pre-load varied by rotation and axial adjustment of the outer part 93 of the collar device 91 relative to the inner part 92. As shown most clearly in
The on-board power unit of the invention enables installation on a “Softail” type of motorcycle in a manner that is fully integrated into the “Softail” look, and so not detracting from the visual aesthetic of the motorcycle and its resemblance to a “Hardtail”. However, when installed, the unit enables the motorcycle to be adjusted from standard height, to over 2.5 inches down, with the adjustment taking only a few seconds. The unit is able to provide a steady, controlled and linear operation to raise or lower ride height, and is able to avoid leaking down from a chosen height, even after long rides or extended storage periods. It enables adjustment for owners who want to “Slam” their rides; that is, to adjust to an extent resulting in a rigid frame ride by cancelling the action of the shock absorbers. Also, the unit retains the benefit of a fully hydraulic suspension that attaches to the OEM springs and shockers, using rather than scrapping them, and avoiding recourse to the use of airbags. The unit facilitates use of precision engineering and use of aircraft quality billet aluminium and steel alloys. Additionally, when including the modified adjuster plate with the two-part collar device, the unit can be readily adjusted to firm up the ride for better handling, to adjust when a pillion passenger is to be carried, or to offset “spring sag”.
