Abstract:
An accumulator assembly is includes a piston located within a pressure canister. The pressure canister has a piston stop therein. The piston stop is located radially outboard of a biasing member or spring located within the pressure canister between the pressure canister and the piston. A support bracket is disposed on an end of the pressure canister in alignment with the spring. The outboard piston stop and the support bracket reduce the stresses due to reaction forces when the accumulator assembly is fully charged. By reducing the stresses due to reaction forces, the accumulator assembly can be made from steel casting or plastic molding without sacrificing the charge capacity of the accumulator assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/314,531, filed on Mar. 16, 2010. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to an accumulator assembly, and more particularly to a transmission accumulator assembly having structural support and housing features to maximize manufacturing flexibility. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0004]    A typical automatic transmission includes a hydraulic control system that is used to provide lubrication, cooling, and control to various components of the transmission. A pump circulates the hydraulic fluid under pressure throughout the transmission. The pump is typically driven by the engine of the motor vehicle. During stop and start conditions, it is desirable to turn off the engine in order to maximize fuel efficiency. However, turning off the engine in turn turns off the pump. In order to prime control devices within the transmission, such as clutches and brakes, an accumulator may be employed within the hydraulic control system to provide pressurized hydraulic fluid to the control devices so that the control devices may be engaged quickly without waiting for reengagement of the pump. Current accumulator designs are manufactured from castings of aluminum in order to have sufficient strength. While these accumulator designs are useful for their intended purpose, there is room in the art for an accumulator assembly that provides maximum manufacturing flexibility without reducing the performance characteristics of the accumulator. 
       SUMMARY 
       [0005]    An accumulator assembly is provided. The accumulator assembly includes a piston located within a pressure canister. The pressure canister has a piston stop therein. The piston stop is located radially outboard of a biasing member or spring located within the pressure canister between the pressure canister and the piston. A support bracket is disposed on an end of the pressure canister in alignment with the spring. The outboard piston stop and the support bracket reduce the stresses due to reaction forces when the accumulator assembly is fully charged. By reducing the stresses due to reaction forces, the accumulator assembly can be made from steel casting or plastic molding without sacrificing the charge capacity of the accumulator assembly. 
         [0006]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0007]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0008]      FIG. 1  is a front isometric view of an accumulator assembly according to the principles of the present invention; 
           [0009]      FIG. 2  is a side view of the accumulator assembly according to the principles of the present invention; 
           [0010]      FIG. 3  is a front view of the accumulator assembly according to the principles of the present invention; 
           [0011]      FIG. 4  is an end view of the accumulator assembly according to the principles of the present invention; and 
           [0012]      FIG. 5  is a cross-sectional view of the accumulator assembly according to the principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0014]    With combined reference to  FIGS. 1-5 , an accumulator assembly according to the principles of the present invention is generally indicated by reference number  10 . The accumulator  10  is an energy storage device in which a non-compressible hydraulic fluid is held under pressure by an external source. In the example provided, the accumulator  10  is a spring type accumulator that provides a compressive force on the hydraulic fluid within the accumulator  10 , as will be described in greater detail below. The accumulator  10  is preferably employed within the hydraulic control system of an automatic transmission (not shown) to enable stop-start operations, however, it should be appreciated that the accumulator  10  may be employed in various other environments, such as fuel injectors, air conditioning systems, etc., without departing from the scope of the present invention. 
         [0015]    The accumulator  10  includes a pressure canister  12  and an end cap  14 . The pressure canister  12  is generally cylindrical in shape and includes an open end  16  and a closed end  18  opposite the open end  16 , best seen in  FIG. 5 . The open end  18  communicates with a cavity  20  defined by an inner surface  22  of the canister  12 . The inner surface  22  has two portions: a first or small portion  24  and a second or large portion  26 . The first portion  24  is located proximate the closed end  16  and has a first diameter. The second portion  26  is located between the first portion  24  and the open end  18  and has a second diameter. The second diameter is greater than the first diameter. The interface or junction between the first and second portion  24  and  26  forms a radially extending piston stop  28 . 
         [0016]    A piston  30  is disposed within the pressure canister  12  and is translatable along an axis “A”. The piston  30  includes a disc plate portion  32  and an axially extending rim portion  34 . The rim portion  34  extends towards the closed end  16  of the pressure canister  12  and has a distal end surface  36 . The piston  30  is slidably disposed within the second portion  26  of the pressure canister  12  and has an outer diameter approximately equal to the second diameter of the second portion  26 . The piston  30  is sealed to the inner surface  22  of the pressure canister  30  via a radial seal  38 . 
         [0017]    A biasing member or spring  40  is disposed within cavity  20  of the pressure canister  12  between the closed end  16  and the piston  30 . A first end  42  of the spring  40  contacts the closed end  16  and a second end  44  of the spring  40  contacts an inner surface  46  of the piston disc portion  32  radially inwardly of the rim portion  23 . The spring  40  biases the piston  30  towards the open end  18  of the pressure canister  12 . 
         [0018]    The end cap  14  is connected to the pressure canister  12  and is disposed overtop the open end  18 . The end cap  14  includes a radial seal  50  that seals the end cap  14  to the inner surface  22  of the pressure canister  12 . The end cap  14  is secured to a radial flange  52  on the pressure canister  14  disposed around the open end  18 . In the example provided, the end cap  14  is secured via bolts  5  that extend through the flange  52  and the end cap  14  or via any other type of mechanical fastener. However, where the pressure canister  12  is made from a plastic, the end cap  14  is preferably welded to the flange  52 . 
         [0019]    The end cap  14  has an inlet/outlet port  54  that communicates with a channel  56  formed within the end cap  14 . The channel  56  communicates with an opening  58  in the end cap  14 . The opening  58  is recessed into the end cap  14  and communicates with an outer surface  60  of the piston  30  within the cavity  20 . The inlet/outlet port  54  also communicates with a tube or passageway  62 . The pipe  62  is secured to the end cap  14  via a connector ring  64  having an opening for receiving the pipe  62  and an opening for receiving a fastener, such as a bolt  66 , to secure the connector ring  64  and therefore the pipe  62  to the end cap  14 , as best seen in  FIG. 3 . A similar connector ring  68  is illustrated at an opposite end of the pipe  62 , though the pipe  62  may be connected to the end cap  14  and to any other component in any other way without departing from the scope of the present invention. 
         [0020]    The accumulator assembly  10  further includes a support bracket  70  connected to an outer surface  72  of the closed end  16  of the pressurized canister  12 , as best seen in  FIG. 4 . The support bracket  70  includes a first flange portion  74  connected to the outer surface  72 . The first flange portion has a semi-circular or circular shape that aligns with the first end  42  of the spring  40  within the pressure canister  12 . The support bracket  70  also includes a second flange portion  76  that extends out from the first flange portion  74 . The second flange portion  76  is illustrated as being at a right angle to the first flange portion  74 , but it should be appreciated that the second flange portion  76  may have other shapes and configurations with respect to the first flange portion  74  without departing from the scope of the present invention. The second flange portion  76  is configured to connect with a fixed component within a transmission, such as the transmission case or housing. In the example provided, the second flange portion  76  includes a bolt hole  78 , though it should be appreciated that various other methods of attachment may be employed without departing from the scope of the present invention. The support bracket  70  further includes a support rib  80  along a periphery of the support bracket  70  to add strength to the support bracket  70 . 
         [0021]    During operation of the accumulator assembly  10 , the accumulator assembly  10  is charged when pressurized hydraulic fluid enters the end cap  14  via the pipe  62  and contacts the piston  30 . The piston  30  is forced against the biasing force of the spring  40 . When the distal ends  36  of the piston  40  contact the stop  28 , the piston  40  is in its maximum charged state. Accordingly, the forces acting on the pressure canister  12  are distributed along the stop  28  as well as on the closed end  16  where the spring  40  contacts the closed end. This reaction force is then transferred to the support bracket  70  and in turn to whatever the support bracket  70  is fixed. By distributing the reaction forces of the piston  30  and spring  40  on the pressure canister  12 , the stress on the pressure canister  12  is reduced and the pressure canister  12  is able to handle a greater force load. This allows the pressure canister  12  to be manufactured using steel casting or plastic molding without reducing the charge capacity of the accumulator assembly  10 . Increased manufacturing flexibility offers cost savings and additionally weight savings which in turn improve the efficiency of the motor vehicle. 
         [0022]    The description of the invention is merely exemplary in nature and variations that do not depart from the general essence of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.