Abstract:
A steering damper system and method of regulating the fluid pressure of such a system are provided. The system can comprise a piston rod, a cylinder, a passage, and a damper portion. The damper portion can comprise a damper cavity, an outer piston, an inner piston, and a biasing component. The damper cavity can be in fluid communication with the passage. The outer piston can be slidably disposed in the damper cavity and define a chamber and a duct that is in fluid communication with the chamber and the passage. The inner piston can be slidably disposed in the chamber of the outer piston. The biasing component can exert an axial biasing force against the inner piston for regulating the pressure of fluid disposed in the system passing intermediate the passage, the damper cavity, and the chamber of the outer piston.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit and priority to and is a U.S. National Phase of PCT International Application Number PCT/SE2006/000951, filed on Aug. 17, 2006, designating the United States of America and published in the English language, which claims priority under 35 U.S.C. §119 to Swedish Application Number 0501836-1, filed on Aug. 19, 2005, the disclosures of the each of which are hereby incorporated by reference in their entireties. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, among other things, to a method for arranging a separating piston in a system cavity where a liquid medium is sealed off and separated from a second medium, for example, a gas, by means of the separating piston. 
     The invention also relates to a device with a separating piston in a system cavity, for example, a steering damper cavity, where the piston seals off and separates a liquid medium from a second medium, for example, a gas. 
     2. Description of the Related Art 
     When arranging a separating piston in a cavity, the separating piston should be positioned in the cavity at an initial position such that it can carry out its function with regard to maintaining the pressure within a predetermined pressure range. The system and the device must be able to compensate for changes in volume as a result of changes in temperature, leakage, etc, so that the system, the steering damper, etc, has the same damping characteristics in spite of the said varying factors. 
     Setting the initial position of the separating piston in the cavity is critical and has hitherto involved a complicated method. In order to set the initial position using this method, one is required to use a special tool. Further, it is necessary to empty the system of the liquid medium in order to carry out the setting. In the case of replacement or repair of a separating piston in an existing system that is in use, this means that the whole system must be emptied of liquid in order to carry out the replacement or repair. 
     SUMMARY OF THE INVENTION 
     The objects of the present invention are, among other things, directed at providing an improved method of arranging a separating piston in a cavity and setting an initial position of the piston. Further, an object of the present invention is to facilitate non-critical setting of the initial position of the separating piston without draining liquid from the system. Accordingly, the separating piston can be given an initial position that takes into account any variations in pressure between the upper and lower sides of the separating piston resulting from the said temperature variations, leakage, etc. 
     In an embodiment of the method, a liquid medium is introduced into a cavity. Further, a first part of a separating piston is lowered into the cavity filled with a liquid medium in a direction towards the inner part of the cavity. A second part of the separating piston can then be lowered into the cavity and is caused to interact with the first part of the piston by the application of an interaction force, for example via an actuating area located on the second piston. A volume of liquid is thereby confined between the parts of the piston by this interaction. Following this interaction, the second part of the piston is subjected to continued downward-pressing forces with the result that parts of the second piston are urged to continue to penetrate into the first part of the piston. 
     Accordingly, at least a portion of the confined volume of liquid is forced out into another cavity under the first part of the separating piston through a passage in the first part of the separating piston. At this point, the volume of liquid thus forced out acts upon a lower area of the first part which can be larger than a lower area of the second part of the separating piston. As a result of the difference in area between the in the surface area of the lower area of the first part and the lower area of the second piston, the downward-pressing force causes the first part of the piston to move upwards in relation to the second part of the separating piston. The relative motion can be ended when the first and second parts are pressed together into a final position, so that the separating piston as such is at a distance from the inner parts of the other cavity. A biasing mechanism, for example a mechanical spring, can then be arranged to act on the separating piston at an upper part of the second part of the separating piston. 
     Accordingly, an embodiment of the method is provided through which the pressure of a fluid in a steering damper system can be regulated. The method can comprise the steps of: filling a damper cavity with the fluid; placing an outer piston into the damper cavity such that the outer piston is slidably disposed in the damper cavity and forms a fluid-tight seal with an interior surface of the damper cavity, the outer piston defining a chamber and a duct that is in fluid communication with the chamber and the fluid in the system; moving the outer piston downwardly into the damper cavity such that the outer piston is submerged in the fluid, the fluid passing through the duct in the outer piston and into and above the chamber of the outer piston; placing an inner piston into the chamber of the outer piston such that the inner piston is slidably disposed in the chamber of the outer piston and forms a fluid-tight seal with an interior surface of the chamber; exerting an axial force against the inner piston such that fluid disposed in the chamber of the outer piston is urged into the damper cavity through the duct of the outer piston and until a lower surface of the inner piston contacts a stop surface of the chamber of the outer piston; and biasing at least a portion of the inner piston against a portion of the damper cavity. 
     The method can also comprise positioning the outer and inner pistons at a given distance above a bottom surface of the damper cavity after the lower surface of the inner piston contacts the stop surface of the chamber of the outer piston. Further, the step of biasing at least a portion of the inner piston can comprise inserting a spring into the damper cavity. In addition, the method can also comprise biasing the spring against an internal surface of a closure part that is connected to the damper cavity for closing the damper cavity. The method can also comprise the step of adjusting an available volume of the system using a pressure regulation device. In such an embodiment, the system can comprise a passage that is in fluid communication with the damper chamber, and the pressure regulation device can be operative to vary the volume of the passage. 
     An embodiment of a device according to the invention can comprise a separating piston having first and second parts. The first part can be arranged to be able to be inserted into a liquid medium towards an inner part of a cavity. The second part can similarly be arranged to be inserted into the liquid medium and can be partially pressed down, by downward-pressing forces, into the first part of the piston. 
     In the partially pressed-down position of the second part, the first and second parts of the piston can contain a volume of liquid medium in a chamber of the first part. The first part can be provided with a passage leading from the chamber in a direction towards the inner part of the cavity. The passage can be arranged to allow all or part of the confined volume of liquid medium to pass through as a result of the downward-pressing forces on the second part of the piston. In this regard, the first part can have a lower area and the second part can have a downward-pressing lower area which presses the fluid downwardly. The lower area of the first part can be larger than the lower area of the second part. As such, the downward-pressing forces can cause the volume of liquid medium that has been forced out of the chamber to make contact with the lower area of the first part and hence cause the first part of the piston to move from the inner part of the cavity towards the second part of the piston to a final combined position. The final combined position for the parts of the piston can be at a distance from the inner part of the cavity. In order to maintain the downward-pressing forces and pressurization of the liquid medium, the second piston can interact with a biasing mechanism. 
     In further developments of the concept of the invention, the first part of the piston can be tubular and the chamber can be an inner cavity that receives at least a portion of the second part of the piston. An end part of the first part of the piston can comprise the passage in the form of a central hole that extends through the first part of the piston, and the first part of the piston can have a seal at the end part that can interact with an inner wall of the cavity. The end part can have the lower area on its outside. 
     The second part of the piston can be arranged to be inserted in the inner cavity of the first part of the piston and can be sealed against the inner wall of this cavity by means of a sealing arrangement. In an additional embodiment, the actuating area of the second piston can comprise an outer flange surface, upon which the biasing mechanism can be arranged or can make contact. Further, in some embodiments, the biasing mechanism can be in form of a mechanical spring. In addition, the second part of the piston can have a central part that extends upwards. 
     Furthermore, the distance of the final combine position of the parts of the separating piston from the inner part of the cavity can be selected to ensure that the separating piston carries out movements within the system cavity within the limits in which the separating piston is to operate. A considerable part or all of the confined volume of liquid medium can have been forced out of the chamber of the first part through the passage when the downward-pressing forces cause the parts of the piston to assume a completely combined, final, or pressed-together position. At its outer end surface, the first piston can have a peripheral contact surface that can make contact with a corresponding stop surface in the inner part of the system cavity, and the inner part can have an opening that is opposite the central hole in the first part of the piston, into which the confined volume of the liquid medium is initially able to be forced down. 
     In an embodiment of the device, a steering damper system is provided that can comprise a piston rod and a damper module. The piston rod can comprise an elongate shaft, a piston component and a mounting section. The piston component can be fixed along the shaft of the piston rod and define a diameter larger than a diameter of the shaft. 
     The damper module can comprise a cylinder, a passage, a pressure regulation portion, and a damper portion. The cylinder can define top and bottom ends and can be configured with the piston rod being slidably disposed therein. The cylinder can define an inner surface having a diameter greater than the diameter of the piston component to form a seal with the piston component. The cylinder can define upper and lower sections. The upper section can be that portion of the cylinder intermediate the piston component and the top end of the cylinder. The lower section can be that portion of the cylinder intermediate the piston component and the bottom end of the cylinder. 
     The passage can be in fluid communication with the upper and lower sections of the cylinder, the passage defining a volume. The pressure regulation portion can be in communication with the passage and being operative to modify the volume of the passage for regulating the pressure of a fluid disposed within the passage and the upper and lower sections of the cylinder. 
     The damper portion can comprise a damper cavity, a separating piston component and a biasing component. The separating piston component can be slidably disposed within the damper cavity to define first and second sections of the damper cavity. The second section of the damper cavity can be in fluid communication with the passage. The separating piston component can comprise outer and inner parts. The outer part can be slidably disposed within the damper cavity and can be configured to form a seal with an inner surface of the damper cavity. The outer part can comprise an interior chamber and a duct. The duct can be in fluid communication with the interior chamber of the outer part and the second section of the damper cavity. The inner part of the separating piston component can be slidably disposed within the interior chamber of the outer part of the separating piston component and can be configured to form a seal with an inner surface of the interior chamber. The biasing component can be disposed in the first section of the damper portion and can bias the inner part of the separating piston component against the damper portion. 
     In some embodiments, the outer and inner parts of the separating piston component can each define a bottom surface, and the bottom surface of the outer part can have a larger surface area than the bottom surface of the inner part. Further, an axial force exerted against the inner part in the direction of the second section of the damper cavity can cause movement of the inner part relative to the outer part and movement of the outer part relative to the damper cavity. The axial force can also cause the inner part to move in the direction of the second section of the damper cavity and the outer part to move in the direction of the first section of the damper cavity. 
     It is contemplated that the second section of the damper cavity of the damper portion can be filled with the fluid. Accordingly, the biasing component can bias the inner part to maintain the pressure of the fluid in the damper system. The biasing element can be a spring. Further, the inner part of the separating piston component can define an actuating area upon which the spring can exert an axial force. The inner part of the separating piston component can also have a central part that extends upwardly, and the central part can be configured to stabilize the biasing component. Finally, the interior cavity of the outer part of the separating piston component can define a stop surface. The stop surface can be configured to contact the bottom surface of the inner part of the separating piston component for limiting the movement of the inner part relative to the outer part of the separating piston component. 
     In accordance with yet another embodiment, a steering damper system is provided that comprises a piston rod, a cylinder, a passage, and a damper portion. The piston rod can comprise an elongate shaft, a piston component and a mounting section. The piston component can be fixed along the shaft of the piston rod. The cylinder can be configured with the piston rod slidably disposed therein and forming a seal between the piston component and an interior surface of the cylinder. The cylinder can be configured with the piston component being interposed between upper and lower sections of the cylinder. The passage can be in fluid communication with the upper and lower sections of the cylinder. 
     The damper portion can comprise a damper cavity, an outer piston, an inner piston, and a biasing component. The damper cavity can be in fluid communication with the passage. The outer piston can be slidably disposed in the damper cavity and define a chamber and a duct that is in fluid communication with the chamber and the passage. The inner piston can be slidably disposed in the chamber of the outer piston. The biasing component can exert an axial biasing force against the inner piston. Accordingly, the axial biasing force can bias the inner piston for regulating the pressure of fluid disposed in the system passing intermediate the passage, the damper cavity, and the chamber of the outer piston. 
     In variations of such an embodiment, the chamber of the outer piston can defines a stop surface, and the stop surface can be configured to contact a bottom surface of the inner piston for limiting the movement of the inner part relative to the outer piston. The inner piston can also have a central part that extends upwardly, and the central part can be configured to stabilize the biasing component. The passage can define a volume and the system can further comprise a pressure regulation portion in communication with the passage, the pressure regulation portion and being operative to modify the volume of the passage for regulating the pressure of the fluid in the system. 
     By means of what is proposed above, a reliably-operating and advantageously-constructed separating piston can be obtained. Further, in spite of the fact that the system can comprises two parts of a piston, it can be constructed in such a way that the parts of the piston maintain their relative positions in a combined position as a result of the ratio of their areas. The system can be filled with liquid when the piston is inserted and the distance to the inner parts can be given a value that enables the separating piston to operate within fixed or predetermined limit values in, preferably, a steering damper. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The abovementioned and other features, aspects and advantages of the inventions disclosed herein are described in detail below with reference to the drawings of the preferred embodiments. The illustrated embodiments are intended to illustrate, but not to limit the inventions. The drawings contain the following figures: 
         FIG. 1  is a vertical cross-sectional view of a steering damper that is arranged and configured in accordance with certain features, aspects and advantages of the present invention, and 
         FIGS. 2   a - 2   b  are vertical cross-sectional views of parts of an accumulator comprised in the steering damper according to  FIG. 1 , in which the parts of the piston assume different positions in relation to each other when the method is implemented. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows an embodiment of a steering damper  1  that is arranged and configured in accordance with certain features, aspects and advantages of the present invention. The basic construction of the steering damper  1  can be of a known type and, for example, consists of the Ohlins SD100 or SD200 steering damper sold on the general market by the applicant of the present patent application. 
     The steering damper can comprise one or more mounting devices  2  for mounting the steering damper  1  onto the handlebars of a motorcycle, cycle, etc, (not shown in  FIG. 1 ). In addition, other mounting devices  3  can be provided for mounting the steering damper  1  to the frame or chassis of the vehicle (not shown). 
     The steering damper preferably comprises a piston rod  4  extending in the longitudinal direction of the damper  1  that has a mounting device  3  at one end. A piston (or piston arrangement)  5  can be fixed on the piston rod  4 . The piston  5  preferably operates in a liquid medium  6  that has been introduced into the cavity  7  of the steering damper  1 . The cavity  7 , the piston rod  4  and the piston  5  can be operatively associated with a part  8 , such as a cylinder, in or on which a mounting device  2  can be arranged. The piston rod  4  is preferably positioned and arranged so that it passes through the ends of the part  8  and has sealing devices  10  that allow a movement between the rod and the part  8 . 
     The steering damper  1  can also comprise a unit  11  that can be connected to the part  8 . The unit  11  can comprise a duct system with ducts  12 ,  13  and  14  that make possible for liquid to pass between the upper and lower sides  5   a  and  5   b  of the piston  5 . In other words, the duct system can connect the partial cavity  7   a  above the piston  5  with the partial cavity  7   b  below the piston  5 . 
     In accordance with the illustrated embodiment, the unit  11  can also comprise a reservoir for a unit  15 , such as a damper portion. The reservoir can assist in maintaining the pressure of the liquid and ensuring that the steering damper  1  can retain its damping characteristics within predetermined variations in temperature, in the event of minor leakage in the steering damper  1 , etc. 
     In  FIG. 1 , a unit  15 ′ is also shown enlarged and in a protruding position. The unit  11  has a longitudinal opening  16 , in which the unit  15  (or  15 ′) can be mounted. The unit  11  can also be provided with a pressure-regulating device  17  of a known type. 
     The unit  15 ,  15 ′ shows a piston arrangement (or separating piston)  18  that operates between the liquid  6  (for example hydraulic oil) in the steering damper  1  (the system) on the underside  18   a  of the separating piston and a gaseous medium  19 , (for example air), on the upper side  18   b  of the separating piston. The unit  15 ,  15 ′ can define a cavity  20 , and the cavity  20  can define partial cavities  20   a  and  20   b  in which gas and liquid mediums can be received. 
     In the embodiment shown in  FIG. 1 , a spring  21  can be operatively connected to the separating piston of the separating piston  18 . The spring  21  can comprise a spiral spring, and in the example illustrated in  FIG. 1 , the spring  21  can be in contact with an actuating area  18   p  of the separating piston. The spring  21  can be attached between the actuating area  18   p  and an internal surface  22  on a part (a nut)  23 . The part  23  can serve to close the cavity  20 . Accordingly, the separating piston  18  can operate against the effect of the spring  21 . Nevertheless, the operation or biasing force of the spring can also be achieved by other means and arrangements. 
     At its other end, the unit  15 ,  15 ′ can be provided with a connecting arrangement  24  for connecting the partial cavity  20   b  to the duct arrangement of the unit  11 . At one end, the unit  15 ,  15 ′ can have a sealing element  25  that seals the unit against an inner surface on the cavity  16 . The separating piston  18  can also be provided with a sealing element  26  that seals off the unit against an inner surface  20   c  in the cavity  20 . The cavity  20   a  can be connected to the surrounding atmosphere  27  via a passage (hole)  28 . The passage  28  can be, for example, disposed in the nut  23  that is connected to the unit  15 ,  15 ′ in such a way that it forms a seal. A (tubular) part, which surrounds the cavity  20  and the separating piston  18 , is indicated by  29 . 
       FIGS. 2   a  and  2   b  show the assembly and the arrangement for the construction of the separating piston  18  in greater detail. A method of operating the steering damper to set an initial position of the separating piston  18  can be considered to work in three steps or phases, with  FIG. 2   a  showing the first step,  FIG. 2   b  showing the second step and  FIG. 1  showing the third step. 
     In accordance with such an embodiment of the present invention, a method for providing a steering damper will now be described with reference to  FIGS. 1-2   b . In a first step, illustrated in  FIG. 2   a , a liquid medium  6  can be introduced or will have been introduced into the cavity  20 . As illustrated, the separating piston  18  can comprise first and second parts  18   c ,  18   d . The first part  18   c  of the separating piston  18  can be inserted down into the liquid medium in a direction towards the inner part  30  of the cavity  20 . The first part  18   c  of the separating piston  18  can define a lower area  18   f  on the underside  18   a  of the separating piston  18 . 
     In a second step, illustrated in  FIG. 2   b , the second part  18   d  of the separating piston  18  can be inserted down into the cavity  20 . The second part  18   d  of the piston  18  can then be caused to interact with the first part  18   c  of the separating piston  18  by the application of an interaction force F 1  via an actuating area  18   e  and/or  18   p  located on the second piston. A volume  31  of the liquid  6  can thereby be confined between the first and second parts  18   c ,  18   d  of the separating piston  18  by the interaction. 
     In a third step, illustrated in  FIG. 1 , the second part  18   d  of the piston  18  can be subjected to downward pressing forces, via the actuating area  18   e  and/or  18   p , that correspond to or exceed the said forces F 1 . 
     Application of this downward-pressing force F 1  can overcome of the friction forces between the first part  18   c  and the second part  18   d  of the separating piston  18 . Thus, parts  18   g  of the second part  18   d  of the separating piston  18  are urged to continue to be inserted into the first part  18   c  of the separating piston  18 . 
     As a result of the application of the downward-pressing force F 1 , a portion of the confined volume of liquid  31  is forced out into the cavity  32  below the first part  18   c  of the separating piston  18  via a passage  33  in the first part  18   c . The volume of liquid that is forced into the cavity  32  acts upon a lower area  18   f  of the first part  18   c  of the separating piston  18 . The lower area  18   f  of the second part  18   d  of the separating piston  18  is larger than down-ward pressed area  18   h  of the first part  18   c  of the separating piston  18 . As a result of the difference in area of the downward pressed area  18   h  and the lower area  18   f , the first part  18   c  of the separating piston  18  will be caused to move upwards in relation to the second part  18   d  of the separating piston  18  by the downward-pressing force F 1 . Finally, as illustrated in  FIG. 1 , continued application of the downward-pressing force F 1  can cause the first part  18   c  of the separating piston  18  to reach a final position in which the first part  18   dc  is pressed together with the second part  18   d  of the separating piston  18 . In such a position, the separating piston  18  may be located as such is at a distance A from the inner parts of the cavity  20 . 
     The spring  21  can thereafter be set or positioned onto the unit  15  to act against the separating piston  18 . For example, in some embodiments, the spring  21  can be operatively associated with the upper part  18   e  of the second part  18   d  of the separating piston  18  or with the actuating area  18   p  of the second part  18   d , which can be located on the upper part  18   e . Further, the second part  18   d  of the separating piston  18  can have a sealing arrangement  34  for sealing the second part  18   d  of the separating piston  18  against an inner surface  35  of an inner cavity  36  of the first part  18   c  of the separating piston  18 . 
     In accordance with the illustrated embodiment, the second part  18   d  of the separating piston  18  can also have an internal guide  37  for the spring  21 . The spring  21  can therefore extend down between the guide  37  and an inner wall in the first part  18   c  of the separating piston  18  to interact with the actuating area  18   p . In this manner, guide  37  can facilitate control of the spring  21 . 
     The embodiment illustrated in  FIGS. 1-2   b  illustrates that when inserted into the liquid  6 , the separating piston  18  can comprise first and second parts  18   c ,  18   d  of the separating piston  18  that can be pressed together. The ratio of the down-ward pressed area  18   h  and the lower area  18   f  is preferably selected in such a way that the relative combined positions established at the time of the insertion are retained when the force of the spring  21  is applied. 
     Further, the embodiment can be configured such that before the second part  18   d  of the separating piston  18  is inserted into the first part  18   c  of the separating piston  18 , the lower area  18   a  of the first  18   c  piston part can rest on a stop surface  38  of the inner part  30 . While the second part  18   d  is being inserted, the first part  18   c  of the separating piston  18  can be raised from the inner parts  30  of the cavity  20  by the distance A. This can ensure pressurization and may provide the same damping characteristics in the damper irrespective of variations in temperature, leakage, etc. 
     Finally, the inner part  30  of the cavity  20  can also include an opening/cavity  32  that is opposite the central hole  33  in the first part of the piston  18   c , in which the confined volume  31  is initially able to be forced down. In an embodiment, the whole confined volume  31  can be initially forced out between the first and second parts  18   c ,  18   d  of the separating piston  18 . In accordance with another embodiment, the upper part of the second part  18   d  of the separating piston  18  can be provided without the guide  37 . In yet another embodiment, the second part  18   d  of the separating piston  18  does not need to be pressed into the first part  18   c  of the separating piston  18  but can be positioned or disposed over the first part  18   c  of the separating piston  18  and hence confine a volume in a corresponding way. 
     Although these inventions have been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. In addition, while several variations of the inventions have been shown and described in detail, other modifications, which are within the scope of these inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combination or sub-combinations of the specific features and aspects of the embodiments can be made and still fall within the scope of the inventions. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of at least some of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above.