Patent Abstract:
A damper for use in vehicle and automotive applications can include a structure for sealing a top portion of the damper such that standing water is prevented from residing adjacent the cylinder/tube, piston rod, gaskets, o-rings, grommets, or other structures located at a top portion of the damper. The structure for sealing the top portion of the damper can include a seal that is located between a rod guide and the damper tube such that water and debris are kept from entering an inner portion of the damper mechanism.

Full Description:
BACKGROUND 
     1. Field 
     The disclosed subject matter relates to a vehicle damper and a method of manufacturing the same. More specifically, the disclosed subject matter relates to a rod guide and sealing structure for a vehicle damper and the sealing method therefore. 
     2. Brief Description of the Related Art 
     Vehicle dampers are used in conjunction with vehicle suspension systems to absorb unwanted vibrations which occur during operation of the vehicle. In order to absorb this unwanted vibration, vehicle dampers are connected between the sprung mass (the body) and the unsprung mass (the suspension system) of the vehicle. A piston is located within a pressure tube of the vehicle damper and is connected to either the sprung mass or possibly the unsprung mass of the vehicle. The pressure tube is connected to the other of the unsprung mass or sprung mass of the vehicle and is filled with hydraulic fluid. Because the piston has the capability of limiting the flow of hydraulic fluid within the pressure tube when the vehicle damper is compressed or extended, the vehicle damper is able to produce a damping force which counteracts the vibrations which would otherwise be transmitted from the suspension (unsprung mass) to the body (sprung mass) of the vehicle. 
     A conventional dual tube vehicle damper includes a pressure tube with a piston disposed therein and a reserve tube surrounding the pressure tube. A piston rod is connected to the piston and extends through the upper end of the pressure and reserve tubes. At the lower end of the pressure tube, a base valve is located between the pressure tube and the reserve tube. The base valve controls fluid flow between the working chamber defined by the pressure tube and the reserve chamber defined by the reserve tube. The damping force is created by restricting the flow of fluid through passages in the piston and valve plates which regulate passage of fluid between opposite sides of the piston within the working chamber. 
     Because the piston rod is located on only one side of the piston, a different amount of fluid is displaced on the compression stroke as opposed to the rebound stroke. The difference in the amount of fluid is termed the rod volume. The rod volume of fluid is pushed out of the pressure tube, through the base valve and into the reserve tube during a compression stroke. During a rebound stroke, the rod volume of fluid flows in the opposite direction from the reserve tube, through the base valve and into the pressure tube. 
     The piston rod is supported at its lower end by the piston and is slidingly received at the upper end of the vehicle damper by a rod guide. The rod guide thus functions as a slide bearing for the rod. The rod guide properly positions the piston rod within the pressure tube and also acts as a closure member for both the pressure tube and the reserve tube. A small clearance can be formed between the inner periphery of the bearing portion of the rod guide and the outer periphery of the piston rod in order to provide smooth sliding of the piston rod through the rod guide. The small clearance also allows for the hydraulic fluid to lubricate the interface between the piston rod and the rod guide. 
     In addition to locating the piston rod and closing the pressure and reserve tubes, the rod guide supports and locates a seal assembly which is designed to keep the hydraulic fluid within the vehicle damper and also keep contaminants out of the vehicle damper. The seal assembly normally interfaces between the reserve tube and the rod guide, between the rod guide and the piston rod and possibly between the reserve tube and the piston rod. The seal assembly is designed to keep hydraulic fluid within the vehicle damper as well as keep dirt and other contaminates from entering the vehicle damper. The dirt and contaminants can be present and can adhere to the exposed portion of the piston rod. 
     There have been numerous seal systems designed and developed for meeting the difficult environmental and sealing requirements for vehicle dampers. While these conventional art seal systems are adequate for their intended purpose, the continued development of vehicle dampers and related seal systems has been directed towards dampers that are made of different materials and have different constructions, requiring different types of seals and seal systems. 
     One type of vehicle damper and seal system that is currently under continuous development is a monotube type damper. In a monotube type damper, a second reserve tube is not necessary. Instead, a second “floating piston” is provided within the first tube and is located below the working piston. The floating piston divides a working chamber of the monotube that is filled with hydraulic fluid from a lower chamber that can be filled with gas or other easily expandable/contractible fluid. The working piston is connected to a piston rod and moves with respect to the monotube structure by passing through a sealing structure/system located at an upper end of the working chamber above the working piston, similar to the system described above with respect to a dual chamber damper. 
     A typical monotube damper seal system is shown in  FIG. 2A  in which a seal system includes an aluminum rod guide  910  connected to an end of a single steel tube  972 . The outer portion of the rod guide  910  is sealed with a surface of the inner tube wall  972   b  by O-rings  917  that prevent hydraulic fluid  902  from escaping. Likewise, the inner through hole  911  of the rod guide is sealed at the juncture between the rod guide  910  and the piston rod  941  by a lower inner seal  930 . A lock ring  936  is press fit into an opening in the lower surface  915  of the rod guide  910  to lock the lower inner seal  930  to the rod guide  910 . The rod guide  910  can be locked with respect to the tube  972  via a clinch ring indent in the tube  972  that corresponds to an indent in the rod guide  910 . 
     The top surface  912  of the rod guide  910  is surrounded by a wall of the bordering tube  972  that extends beyond the rod guide  910  and forms a cup with the top surface  912  of the rod guide. This “cup” shaped portion tends to trap water  980  and other dirt and debris  981  at the top of the rod guide  910 . 
     As shown in  FIG. 3 , the water  980  and debris  981  that are trapped by the tube wall  972  and rod guide  910  at the top of the damper  900  can result in a break down of the seal system between the rod guide  910  and either the tube  972  or the piston rod  941 . The break down occurs when the water  980  and/or debris  981  get in between either the piston rod  941  and rod guide  910  or the rod guide  910  and inner surface  972   b  of the tube  972 . The water  980  and/or debris  981  cause the O-ring(s)  917  and/or lower inner seal  930  to deteriorate, resulting in water, debris or hydraulic fluid either entering into the working piston chamber or escaping from the working piston chamber. Over time, this defect can cause deterioration of performance in the damper  900  and possibly failure of the damper  900 . 
     In some monotube dampers the rod guide  910  is made from aluminum (that can be anodized) while the tube  972  is made from steel (which can be galvanized). Thus, at the juncture between these two structures, galvanic corrosion can also occur, which can cause poor performance or failure of the damper sealing system. For example, galvanic corrosion between the rod guide and the piston rod or between rod guide and the damper tube can result in free play and relative movement between the parts, causing unwanted noise and further deterioration and loss of structural integrity for the damper  900 . 
     Thus, there has been a long felt need to improve the sealing system in monotube and other types of dampers, to avoid corrosion and deterioration of the seal system, to improve or broaden the tolerance requirements for the parts that make up dampers, and to improve the overall performance and manufacturability of dampers in general. 
     SUMMARY 
     The disclosed subject matter relates to a vehicle damper and a method of manufacturing a damper. The vehicle damper can be configured as a suspension damper, and alternatively can be configured as an air spring for the trunk or hood of a vehicle, etc. 
     In accordance with an aspect of the disclosed subject matter, a vehicle damper is disclosed that can include a damper tube having a first portion and a second portion located along a longitudinal axis of the damper tube. A piston can be located in the damper tube. A piston rod can be attached to the piston at the first portion of the damper tube and can extend from the first portion of the damper tube to the second portion of the damper tube along the longitudinal axis of the damper tube. A rod guide can be located adjacent the piston rod and the second portion of the damper tube and made from a hard material. A working volume can be located between the rod guide and piston and defined by the damper tube. An outer seal can be located between the rod guide and the damper tube and made from a relatively softer material than the rod guide. The outer seal can include an outer seal top surface that faces away from the working volume. The rod guide can include a rod guide top surface that faces away from the working volume. The damper tube can include a damper tube top surface that faces away from the working volume. The working volume can be located at a first longitudinal axis position with respect to a longitudinal axis direction, the rod guide top surface can be located at a second longitudinal axis position with respect to the longitudinal axis direction, the outer seal top surface can be located at a third longitudinal axis position with respect to the longitudinal axis direction, and the damper tube top surface can be located at a fourth longitudinal axis position with respect to the longitudinal axis direction. The second longitudinal axis position of the rod guide top surface can be spaced from the first longitudinal axis position of the working chamber at a second rod guide longitudinal axis distance, the third longitudinal axis position of the outer seal top surface can be spaced from the first longitudinal axis position of the working chamber at a third outer seal longitudinal axis distance, the fourth longitudinal axis position of the damper tube top surface can be spaced from the first longitudinal axis position of the working chamber at a fourth tube top longitudinal axis distance. The fourth tube top longitudinal axis distance can be less than or substantially equal to the second rod guide longitudinal axis distance. 
     In accordance with another aspect of the disclosed subject matter, the third outer seal longitudinal axis distance can be less than or substantially equal to the second rod guide longitudinal axis distance. 
     In accordance with yet another aspect of the disclosed subject matter, the rod guide top surface, the outer seal top surface, and the top surface of the tube can be configured to cause liquid to continuously move away from the rod guide and towards the damper tube when the damper is in use. 
     In accordance with still another aspect of the disclosed subject matter, the rod guide can be made from an aluminum type material and the damper tube is made from a steel type material. 
     In accordance with another aspect of the disclosed subject matter, the outer seal can include an overhang portion that extends beyond an inner surface of the damper tube in a direction substantially perpendicular to the longitudinal axis of the damper tube. 
     In accordance with an aspect of the disclosed subject matter, the outer seal top surface can be substantially flush with the rod guide top surface. 
     In accordance with still another aspect of the disclosed subject matter, the rod guide can be located at an upper portion of the damper and the piston can be located at a lower portion of the damper, and an imaginary line that extends perpendicular to the piston rod and is in contact with an uppermost portion of the rod guide top surface does not intersect the damper tube. 
     In accordance with another aspect of the disclosed subject matter, the rod guide can be located at an upper portion of the damper and the piston can be located at a lower portion of the damper, and an imaginary line that extends perpendicular to the piston rod and is in contact with an uppermost portion of the outer seal top surface does not intersect the damper tube. 
     In accordance with yet another aspect of the disclosed subject matter, the damper can be a monotube damper. 
     In accordance with an aspect of the disclosed subject matter, the damper can be configured as an active (e.g., magneto-rheological) damper or a traditional semi-active or non-active damper. 
     In accordance with another aspect of the disclosed subject matter, a vehicle damper can include a piston rod having a longitudinal axis extending between an upper portion of the piston rod and a lower portion of the piston rod, a piston attached to the lower portion of the piston rod, a rod guide located adjacent the upper portion of the piston rod and having a top surface located at an uppermost portion of the rod guide, the rod guide made from an aluminum type material, a damper tube located adjacent the piston rod and extending from the upper portion to the lower portion of the piston rod, the damper tube having a top surface at an uppermost portion of the damper tube, and the top surface of the damper tube located substantially co-planar with or lower than the rod guide top surface, an outer seal made of a material that is softer than the material of the rod guide, the outer seal located between the rod guide and the damper tube and including an outer seal top surface at an uppermost portion of the outer seal such that at least the rod guide top surface and the outer seal top surface form an uppermost surface of the damper. 
     In accordance with still another aspect of the disclosed subject matter, a portion of the uppermost surface of the damper that is furthest away from the piston rod is lower than a portion of the uppermost surface of the damper that is closest to the piston rod. 
     Still other features and characteristics of the disclosed subject matter will become apparent to those skilled in the art from a reading of the following detailed description of exemplary embodiments constructed in accordance therewith, and taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed subject matter will become clear from the following description with reference to the accompanying drawings, wherein: 
         FIG. 1  is a cross-sectional view of an embodiment of a vehicle damper made in accordance with principles of the disclosed subject matter; 
         FIG. 2A  is a cross sectional view of a conventional sealing system for a vehicle damper; 
         FIG. 2B  is a cross sectional view of the sealing system of the vehicle damper shown in  FIG. 1 ; 
         FIG. 3  is a cross sectional view of the conventional sealing system shown in  FIG. 2A  after deterioration; 
         FIG. 4  is a cross sectional view of another embodiment of a sealing system for a vehicle damper made in accordance with principles of the disclosed subject matter; and 
         FIG. 5  is a cross sectional view of another embodiment of a sealing system for a vehicle damper made in accordance with principles of the disclosed subject matter. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The disclosed subject matter will now be described in more detail with reference to exemplary embodiments of the vehicle damper and method, given only by way of example, and with reference to the accompanying drawings. 
     The disclosed subject matter relates to a vehicle damper, and more particularly to a sealing system for a vehicle damper. In addition, the disclosed subject matter relates to sealing systems for monotube type vehicle dampers. 
       FIG. 1  shows a cross section of a vehicle damper  100  that includes a tube  172  that encases both a working piston  40  and a floating piston  50 . The working piston  40  is attached to a piston rod  41  by a lock mechanism  42 . The floating piston  50  is located in the tube  172  below the working piston  40  and separates the working chamber hydraulic fluid  302  from a gas  202  located below the floating piston  50 . A lower cap  174   b  encloses the lower end of the tube  172 . A piston rod guide  10  encloses an upper portion of the tube  172  while allowing the piston rod  41  to slide therethrough. 
     An upper connector  176   a  can be provided in an upper cap  174   a  located at the upper portion of the tube  172  for connection to a vehicle frame (or vehicle suspension). Likewise, a lower connector  176   b  can be provided in the lower cap  174   b  located at the lower portion of the tube  172  for connection to a vehicle suspension (or vehicle frame). 
     The working chamber defined by the piston  40  floating piston  50  and damper tube  172  can be referred to as a working volume. Of course, if there is no floating piston  50 , the working volume can be defined by the piston  40 , damper tube  172  and a surface of the lower cap  174   b  (or other structure that contains the hydraulic fluid  302 ). Both the piston rod  41  and damper tube  172  have a longitudinal axis that can be coincident with each other. Typically, the working volume is located lower along the longitudinal axis of either the piston rod  41  or the damper tube  172  than are the rod guide  10 , outer seal  20  or top surface  172   c  of the damper tube  172 . The rod guide  10  can be locked to the damper tube  172  with respect to movement in the longitudinal axis direction by a clinch indent  178  in the tube  172  that mates with an indent  18  in a side of the piston rod guide  10 . 
       FIG. 2B  shows a detailed cross sectional view of the seal system for the vehicle damper  100  shown in  FIG. 1 . In particular, the rod guide  10  includes an upper outer annular rim  13  into which an upper outer seal  20  is fitted. The rod guide  10  can be made from various hard materials, including metals, ceramics, and even some plastics. For example, the rod guide  10  can be made from aluminium or steel. More specifically, the rod guide can be made from an aluminium type material that includes aluminium, aluminium alloys, anodized aluminium, and the like. Moreover, the aluminium type material can include surface treated aluminium, including aluminium that is anodized and then coated with Teflon or other protective coating. 
     The upper outer seal  20  can be made of a relatively softer more pliable material (as compared to the material of the rod guide  10  or the damper tube  172 ) for creating the seal between the rod guide  10  and the damper tube  172 . For example, the upper outer seal  20  can be made from rubber, plastic, soft metals, ceramics, etc., including silicon, polyurethane, and other plastics and rubbers. In particular, the outer seal  20  can be made from a low conductivity rubber when used in a magneto-rheological damper or any damper with an aluminum guide and a steel tube. The low conductivity rubber is used to reduce the possibility of galvanic corrosion between the steel and aluminum. 
     The damper tube  172  can be made from hard materials similar to those from which the rod guide is constructed. Specifically, the damper tube can be made from the aluminium type materials as described above or from steel type materials including steel, steel alloys, galvanized steel, different phase steel materials, and the like. 
     The outer seal  20  can be configured (in conjunction with the structural configuration of the rod guide  10  and damper tube  172 ) to allow water and other debris to roll off of the top surface  12  of the rod guide  10 . For example, the top surface  22  of the upper outer seal  20  can be located lower than the top surface  12  of the rod guide  10 . In addition, an overhang portion  21  can be provided on the outer seal  20  that lies atop an upper rim or upper surface  172   c  of the damper tube  172  so that water and other debris cannot get in between the damper tube  172  and an outer side surface  24  of the outer seal  20 . In addition, the configuration of the outer seal  20  can be slanted or otherwise configured to direct water away from the top surface  12  of the rod guide  10  so that little or no standing water is present on the top surface  12  of the rod guide  10 . An indent can be provided on the inner surface  23  of the outer seal  20  that allows the seal  20  to easily lock with the upper outer annular rim  13  of the rod guide  10 . 
     A lower inner seal  30  can be locked into an inner lower annular indent  16  in the rod guide  10  by a lock ring  36 . The lower inner seal  30  is configured to seal the through hole  11  that exists in the space between the piston rod  41  and the rod guide  10 . The inner seal  30  can be made from a relatively soft material, such as polyurethane and other types of rubbers or plastics, etc. 
     The damper  100  shown in  FIG. 2B  can be a typical damper, but can also be configured as a magneto-rheological damper in which the hydraulic fluid  302  includes magnetic material such that the viscosity of the hydraulic fluid  302  can be changed by applying an electric field to the fluid  302 . For example, an electrical wire core can be provided within the piston rod  41  for producing an electrical field within the hydraulic fluid  302  to provide active control of the damping amount for the vehicle damper  100 . 
       FIG. 4  shows a cross-sectional view of another embodiment of a vehicle damper  100  with a seal system made in accordance with principles of the disclosed subject matter. In this embodiment, the outer seal  20  and rod guide  10  can be configured such that the outer seal  20  has a top surface  22  that is inclined from the top surface  12  of the rod guide  10 . The top surface  22  of the outer seal  20  can terminate at a position corresponding to the outer surface  172   a  of the damper tube  172 . Thus, water and debris travel downwards over the top surface  22  of the outer seal  20  and over the periphery of the rim/top surface  172   c  of the damper tube  172 . In this embodiment, the rod guide  10  extends slightly above the annular rim/top surface  172   c . The rod guide  10  can be provided with an extension knob  19  about the outer wall portion  14  that locks with an indent in the inner portion  23  of the outer seal  20 . 
       FIG. 5  shows a cross-sectional view of another embodiment of a vehicle damper  100  with seal system made in accordance with principles of the disclosed subject matter. In this embodiment, the rod guide  10 , outer seal  20 , and the damper tube  172  can be configured such that the respective top surfaces (i.e., tops surface  12 , top surface  22 , and top surface of annular rim  172   c ) are substantially co-planar. 
     While there has been described what are at present considered to be exemplary embodiments of the invention, it will be understood that various modifications may be made thereto. For example, the outer seal  20  can be configured to extend across the entire top surface  12  of the rod guide  10  as well as the annular rim  172   c  of the tube  172  in order to seal the adjacent portions between the piston rod  41 , rod guide  10 , and tube  172 . In addition, the manner for attaching each of the structures to each other can vary greatly without departing from the spirit and scope of the disclosed subject matter. For example, the knob  19  located at the outer wall surface  14  of the rod guide  10  can instead be configured as an indent that mates with a corresponding knob located on the outer seal  20 . In addition, adhesives, lock rings, or other known attachment structures can be used to attach the upper outer seal  20  to the rod guide  10  and/or tube  172 . 
     The inner seal  30  is shown as located at a lowermost surface  15  of the rod guide  10 . However, other configurations of the inner seal  30  can be incorporated into a damper  100  of the disclosed subject matter. For example, the inner seal  30  can be provided in a central portion or at a top surface  12  of the rod guide  10 . If provided at the top surface  12  of the rod guide  10 , the inner seal  30  can be configured to drive water and debris away from the piston rod  41  and towards the outer portion of the damper tube  172 . For example, the inner seal  30  can have an upper surface that is inclined downwards and away from the piston rod  41 . Of course, other configurations of the upper surface of the inner seal  30  are contemplated and fall within the scope of the disclosed subject matter, even embodiments in which the inner seal  30  does not direct water or debris away from the piston rod  41 . 
     The specific configurations of each of the damper structures can also vary without departing from the spirit and scope of the disclosed subject matter. For example, while the tube  172  can have a symmetrical cross-section when viewed along its longitudinal axis, it can also be non-symmetrical. Specifically, the tube can be circular, oval, square, polygonal or other similar symmetrical shape when viewed in cross-section along its longitudinal axis, or it can be non-uniform and non-symmetrical when viewed in cross-section along its longitudinal axis. Thus, the corresponding shape of the piston, rod guide, outer seal and other portions can also be shaped to correspond to the symmetrical or non-symmetrical tube cross section. 
     In addition, it should be understood that the invention is not only applicable to active, in-active and/or semi-active suspension dampers in a vehicle, but could also be applied to use in dampers such as trunk or hood air springs and other pneumatic or hydraulic cylinder devices used in a vehicle. 
     While there has been described what are at present considered to be exemplary embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover such modifications as fall within the true spirit and scope of the invention. Any conventional art document referenced above is/are hereby incorporated by reference in its entirety.

Technology Classification (CPC): 5