Abstract:
A damper assembly includes a reservoir chamber for supplying hydraulic fluid to a main damper chamber. The reservoir chamber is in fluid communication with damper chamber through an internal fluid passage formed by openings in the damper housing and the reservoir housing. Mating features align the reservoir and damper housing relative to each other.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to a monotube shock absorber with a remote reservoir fluid chamber and specifically to a monotube shock absorber with an integral passage between the reservoir and the damper chamber. 
   Monotube shock absorbers are known in the art to include a reservoir chamber having a quantity of fluid in communication with a main chamber of the shock absorber. The main chamber of the shock absorber includes a piston that divides the chamber and controls the fluid flow between sections of the chamber. The fluid reservoir provides additional hydraulic fluid to the main chamber in response to movement of the piston within the main chamber. 
   The fluid reservoir allows the main chamber to be constructed shorter than normally would be allowed and may allow the use of a larger shaft that connects the piston and shock absorber to one mounting member. The shaft takes up volume within the main chamber and the larger the diameter of the shaft, the less volume available for the storage of hydraulic fluid in the main chamber. For these reasons, it has been found desirable to provide additional hydraulic fluid within a remote reservoir chamber. 
   Typically, communication between the main chamber and the reservoir chamber is provided by a fluid communicating passage such as a flexible hose or steel tubing. As appreciated, the connection between the main chamber and the reservoir chamber requires seals. Dampers typically operate at extreme pressures and each seal is a potential leak point. In addition, an external hose or tube is exposed to potential damage given the harsh environment within which the shock absorber operates. 
   Accordingly, it is desirable to develop and design a reservoir chamber for a shock absorber that eliminates external passageways to prevent potential damage and eliminate potential leak points. 
   SUMMARY OF THE INVENTION 
   The invention is a monotube shock absorber assembly having an integral passageway between the main damper chamber and the reservoir chamber. 
   The shock absorber of this invention includes a damper chamber and a reservoir chamber. The damper chamber and the reservoir chamber are formed by aluminum extrusion to form mating features that combine to form the fluid communication passage between the damper chamber and the reservoir chamber. The extruded mating features are designed to aid assembly and provide an interlocking profile between the main damper chamber and the reservoir chamber. The reservoir chamber is mechanically attached to the main damper chamber such that the reservoir chamber and main damper chamber cooperate to form a passage therebetween. 
   In another embodiment of this invention the damper chamber and reservoir chamber are integrally formed by an aluminum extrusion such that each of the chambers are formed in parallel to another in a common housing. The passageway is then formed between the two chambers to eliminate the need for any seal or mechanical attaching means. 
   Accordingly, the damper assembly of this invention includes a fluid communication passage between the reservoir and the damper chamber eliminating any external passage or fluid connection. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
       FIG. 1  is a cross-sectional view of an embodiment of this invention; 
       FIG. 2  is a cross-sectional view of an embodiment of this invention illustrating the integrally formed mating features; 
       FIG. 3  is a top view of the damper chamber illustrating the key portion integrally formed therein; 
       FIG. 4  is a top view of the reservoir chamber showing the integrally formed keyway slot; 
       FIG. 5  is another embodiment of this invention; and 
       FIG. 6  is a cross-sectional view of the embodiment of FIG.  5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , a damper assembly  10  of this invention includes a first housing  12  defining a damper chamber  16 . The damper chamber  16  includes a piston  22  attached to a shalt  28 . The shaft  28  extends from the damper chamber  16  for mounting of the damper assembly  10 . The opposite end of the housing  12  includes an end cap  26  with a mounting opening  27  used for mounting the damper assembly  10 . The piston  22  divides the chamber  16  into upper and lower portions. The piston  22  moves within the chamber  16  dampening oscillations between two mounting members (not shown) movable relative to each other. As appreciated, the mounting of the damper assembly  10  is known to a worker skilled in the art and any mounting scheme that is known to a worker skilled in the art would be within the contemplation of this invention. 
   The damper chamber  16  is in fluid communication with a reservoir chamber  18 . The reservoir chamber  18  is defined by a second housing  14 . The second housing  14  is mechanically attached to the first housing  12 . Straps  30  secure the second housing  14  to the first housing  12 . Although straps  30  are shown in  FIG. 1 , it is within the contemplation of this invention to use other mechanical attachment means known to a worker skilled in the art. 
   Referring now to  FIG. 2 , mating features  34  align the second housing  14  to the first housing  12  and include a key  36  that is disposed within a keyway slot  38 . The key  36  is preferably formed on the first housing  12  and the keyway slot  38  is preferably formed on the second housing  14 . Also formed within each of the housings  12 ,  14  is a passageway  20 . The passageway  20  provides fluid communication between the damper chamber  16  and the reservoir chamber  18 . The passageway  20  is sealed by an o-ring seal  32  disposed between the housing  12  and  14 . 
   A second piston  24  floats within the reservoir chamber  18 . The piston  24  floats relative to the amount of fluid required by the damper chamber  16 . As is appreciated, the operation of the damper assembly in conjunction with the reservoir chamber  18  is known to a worker skilled in the art. Other configurations of reservoir damper chamber operations are all within the contemplation of this invention. 
   Preferably, the housings  12  and  14  are produced by way of an aluminum extrusion. Aluminum extrusion produces long lengths of the desired mating surfaces as shown in FIG.  2  and each of the housings  12  and  14  are cut to the proper and desired length. Each of the housings  12  and  14  are machined to enable the installation of end caps  26 . End caps  26  may be of any configuration known to a worker skilled in the art. 
   Referring to  FIGS. 2 ,  3  and  4 , the extruded housings  12  and  14  include the integrally formed mating features  34 . The first housing  12  includes the key  36  and the second housing  14  includes the keyway slot  38 . Although a key and key slot configuration is shown in this embodiment, it is within the contemplation of this invention that other integrally formed mating features as are known to a worker skilled in the art are within the contemplation of this invention may also be used. 
   Referring to  FIGS. 5 and 6 , another embodiment of a damper assembly is generally indicated at  50  and includes a common housing  52  for damper chamber  54  and reservoir chamber  56 . The damper chamber  54  includes a piston  60  attached to a shaft  62 . The shaft  62  extends out of the damper chamber  54  for mounting of the damper assembly  50 . Disposed between the damper chamber  54  and reservoir chamber  56  is a passageway  58 . The passageway  58  is integrally formed within the housing  52 . Each end of the housing  52  is closed off by end portions  64 . The end portions  64  are threaded into the housing  52  in order to seal off and provide for hydraulic sealing of fluid within the chambers  54 ,  56 . As appreciated, any end portion for sealing the fluid chambers known to a worker skilled in the art are within the contemplation of this invention. Within the reservoir chamber  56  is a floating piston  68  that operates as is known to a worker skilled in the art. 
   Preferably in this embodiment, an extrusion process is used to form the housing  52  with parallel disposed chambers  54  and  56 . The parallel disposed chambers  54  and  56  form both the damper chamber and the reservoir chamber. As is appreciated, the method of extruding the aluminum profile illustrated in  FIG. 6  is as known to a worker skilled in the art. 
   This invention includes the method of forming damper housing  52  by way of an extruded aluminum profile. The profile shown in  FIG. 6  would include parallel disposed chambers. Parallel disposed chambers are then machined to adjust for the relative size between the damper chamber  54  and the reservoir chamber  56 . Preferably, the reservoir chamber  56  is of a smaller volume relative to the damper chamber  54 . However, any size of reservoir chamber relative to damper chamber as is known to a worker skilled in the art would be within the contemplation of this invention. The passage  58  is then formed to communicate hydraulic fluid between the damper chamber  54  and a reservoir chamber  56 . 
   The foregoing description is exemplary and not just a material specification. The invention has been described in an illustrative manner, and should be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications are within the scope of this invention. It is understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.