Abstract:
A strut-type damper is disclosed. The damper has a shock absorber having a housing with a telescoping piston rod, a coil spring, an upper spring seat operably coupled to a distal end of the piston rod, and a lower spring seat operatively coupled to the housing. The upper and lower spring seats capture the coil spring therebetween. The lower spring seat has a base portion having an opening for receiving the housing and is fixedly securable to the housing. A generally circumferential wall portion extends from the base portion and forms a catcher for catching a broken portion of the coil spring if the coil spring fractures. An impact absorbing structure is formed on the lower spring seat adjacent both of the catcher and the base portion, and is configured to be crushed in the event of a fracture of the coil spring.

Description:
FIELD 
       [0001]    The present disclosure relates to dampers used with motor vehicle suspension systems, and more particularly to a damper having a spring seat designed in a manner, and from a material, which absorbs the energy produced if a coil spring of the damper fractures, and which operates to significantly reduce the chance of the fractured coil spring contacting a wheel of the vehicle. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0003]    Strut-type suspension systems are well known in the motor vehicle industry. Such telescopic suspension systems are also commonly known as McPherson shock absorbers. A strut-type shock absorber assembly normally incorporates a hydraulic damper and is used as one of the locating members for the wheel of the motor vehicle. A strut-type shock absorber assembly typically includes a coil spring concentrically disposed around a shock absorber. The coil spring extends between an upper spring seat, which is a part of a top mount assembly for the strut-type shock absorber assembly, and a lower spring seat, which is attached to the shock absorber component of the strut-type shock absorber assembly. 
         [0004]    The lower spring seat can be a single piece component made of metal or plastic. A plastic spring seat is lighter in weight than its metal counterpart, and for that reason is particular desirable with motor vehicle manufacturers for the reason that it reduces the weight of the overall assembly. An annular inner portion of the lower spring seat is designed to interface with an outer tube of the shock absorber. The lower spring seat supports and maintains the correct position of the coil spring under various driving conditions of the vehicle. The lower spring seat resists braking loads, wear, abrasion, changing loads and impacts by stones and other road debris. 
         [0005]    During a severe impact, however, the coil spring may fail (i.e., fracture). For this reason the lower spring seat may incorporate some structure that acts as a “catcher” to catch the fractured spring and reduce the chance of the fractured spring contacting the wheel of the vehicle. As such, the construction of the lower spring seat is a highly important consideration in the design of a strut-type shock absorber assembly. 
         [0006]    A significant challenge when designing a plastic or composite reinforced spring seat component, however, is the generally low toughness of spring seats made from plastics or composites, when compared to spring seat components made from common metals such as steel. Accordingly, improving the toughness of a spring seat member, and particularly the catcher, without tangibly increasing its weight or expense, has proven to be a significant challenge. 
       SUMMARY 
       [0007]    In one aspect the present disclosure relates to a strut-type damper. The damper may comprise a shock absorber having a housing with a telescoping piston rod projecting at least partially therefrom, a coil spring, an upper spring seat and a lower spring seat. The upper spring seat may be operably coupled to a distal end of the piston rod. The lower spring seat may be operatively coupled to the housing of the shock absorber. The upper and lower spring seats capture the coil spring therebetween. The lower spring seat includes a base portion having an opening for receiving the housing of the shock absorber and is fixedly securable to the housing. The lower spring seat also includes a generally circumferential wall portion extending from the base portion which forms a catcher for catching a portion of the coil spring in an event where the coil spring fractures. An impact absorbing structure is formed on the lower spring seat adjacent both of the catcher and the base portion, and configured to be crushed in the event of a fracture of the coil spring. 
         [0008]    In another aspect the present disclosure relates to a strut-type damper. The damper may comprise a shock absorber having a housing with a telescoping piston rod projecting at least partially therefrom. The damper may also comprise a coil spring, an upper spring seat and a lower spring seat. The upper spring seat may be operably coupled to a distal end of the piston rod. The lower spring seat may be operatively coupled to the housing of the shock absorber, with the upper and lower spring seats capturing the coil spring therebetween. The lower spring seat may include a base portion having an opening for receiving the housing of the shock absorber and may be fixedly securable to the housing. The lower spring seat may also include a generally circumferential wall portion extending from the base portion and integrally formed with the base portion. The generally circumferential wall portion forms a catcher for catching a portion of the coil spring in an event where the coil spring fractures. The lower spring seat further includes a plurality of circumferentially spaced apart, impact absorbing structures formed on the lower spring seat adjacent both of the catcher and the base portion, and extending from an inside wall portion of the catcher. Each impact absorbing structure is configured to be crushed in the event of a fracture of the coil spring and to absorb and dissipate energy from a broken portion of a fractured coil spring. 
         [0009]    In still another aspect the present disclosure relates to a strut-type damper. The damper may comprise a shock absorber having a housing with a telescoping piston rod projecting at least partially therefrom, a coil spring, an upper spring seat and a lower spring seat. The upper spring seat is operably coupled to a distal end of the piston rod. The lower spring seat is operatively coupled to the housing of the shock absorber, with the upper and lower spring seats capturing the coil spring therebetween. The lower spring seat may include a base portion having an opening for receiving the housing of the shock absorber and is fixedly securable to the housing. The lower spring seat also includes a generally circumferential wall portion extending from the base portion and being integrally formed with the base portion. The generally circumferential wall portion forms a catcher for catching a portion of the coil spring in an event where the coil spring fractures. A plurality of circumferentially spaced apart, impact absorbing structures are formed on the lower spring seat adjacent both of the catcher and the base portion, and may extend from an inside wall portion of the catcher. Each impact absorbing structure is configured to be crushed in the event of a fracture of the coil spring and to absorb and dissipate energy from a broken portion of a fractured coil spring. Each impact absorbing structure may include a first crush rib extending from an inside wall portion of the catcher radially inwardly toward an axial center of the lower spring seat. The first crush rib is configured to absorb and dissipate energy from a portion of the coil spring when the coil spring fractures. Each impact absorbing structure may also include a second crush rib for further helping to absorb and dissipate energy from the portion of the fractured coil spring. The second crush rib may be integrally formed with the first crush rib and arranged generally tangentially relative to an axial center of the lower spring seat. The lower spring seat and the impact absorbing structures may also be integrally formed as a single piece component. 
         [0010]    In still another aspect the present disclosure involves using an independent system to absorb impacts. The independent system is formed by a plate having a plurality of rib structures projecting outwardly from a floor portion of the plate. The plate is intended to rest within a catcher portion of a lower spring seat. 
         [0011]    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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0013]      FIG. 1  is a perspective view of a strut-type damper in accordance with one embodiment of the present disclosure in which the damper incorporates a spring seat structure having a new catcher for controllably absorbing energy in the event of a fracture of a coil spring of the damper; 
           [0014]      FIG. 2  is a perspective view of the lower spring seat of the damper of  FIG. 1 ; 
           [0015]      FIG. 3  is an enlarged view of a portion of the lower spring seat better showing the catcher and the impact absorbing structures; 
           [0016]      FIG. 4  is another enlarged view of a portion of the lower spring seat better illustrating a thickness of the strengthening ribs on an outer surface of the catcher relative to a thickness of each one of the crush ribs; 
           [0017]      FIG. 5  is a perspective view of another embodiment of the impact absorbing structures in which a thickness of a second crush rib of the structure is greater than a thickness of a first crush rib of the structure; 
           [0018]      FIG. 6  is a perspective view of another embodiment of the impact absorbing structures in which the crush rib has an upper portion having a first thickness and a lower portion having a second thickness, with the second thickness being greater than the first thickness; 
           [0019]      FIG. 7  is a perspective view of another embodiment of the coil locating ribs in which a portion of the coil locating rib extends into contact with the catcher, to thus further help to strengthen the catcher; and 
           [0020]      FIG. 8  is a side partial cross sectional view showing another embodiment of the present disclosure in which a plurality of impact absorbing structures formed by first and second crush ribs, are instead formed on an independent plate which fits on the base portion of the lower spring seat within the catcher. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0022]    Referring to  FIG. 1  there is shown a strut-type damper  10  in accordance with one embodiment of the present disclosure. The damper  10  in this example includes a shock absorber  12  having a tubular body, an upper spring seat  14 , a coil spring  16  and a lower spring seat  18 . A mounting flange  20  enables the damper  10  to be secured at its lower end to a wheel component of a vehicle, typically a steering knuckle. A telescoping piston rod (not shown) of the shock absorber  12  is typically coupled to the vehicle&#39;s body. The lower spring seat  18  is fixedly secured the outer surface of the tubular shock absorber  12  housing  12   a.    
         [0023]    Referring to  FIG. 2 , the lower spring seat  18  can be seen in greater detail. The lower spring seat  18  includes an eccentrically located bore  22  which helps to define an inner annular flange  24 . The inner annular flange  24  is dimensioned to receive the housing  12   a  of the shock absorber  12 . The inner annular flange  24  extends upwardly from a base portion  26 . A circumferential wall extends perpendicularly from the base portion  26  to form a catcher  28 . A hub portion  30  also extends upwardly from the base portion  26  and helps to locate the lower end of the coil spring  16  on the lower spring seat  18 . Coil locating ribs  32 ,  34  and  36  may also be formed to project upwardly from the base portion  26  to help locate the lower end of the coil spring  16  on the lower spring seat  18 . 
         [0024]    The lower spring seat  18  in this example may be formed from a non-metallic, lightweight material, for example a high strength plastic or a composite. A principal feature of the catcher  28  is the inclusion of a plurality of integrally formed, radially arranged impact absorbing structures  38 . In this example the impact absorbing structures  38  take the form of T-shaped structures when viewed in plan (i.e., when looking straight down on an inside surface  26   a  of the base portion  26 ). 
         [0025]    With reference to  FIG. 3 , a plurality of the impact absorbing structures  38  can be seen in greater detail. Each impact absorbing structure  38  in this example has a radially arranged portion  40  (i.e., arranged generally radially relative to an axial center of the base portion  26 ) which forms a first crush rib  40  and a tangentially arranged portion which forms a second crush rib  42 . Each first crush rib  40  is preferably integrally formed with its second crush rib  42 . 
         [0026]    Since the first crush ribs  40  project from both an inside surface wall portion  28   a  of the catcher  28 , as well as an inner surface  26   a  of the base portion  26 , they are directly exposed to the coil spring impact if the coil spring  16  fractures. The first crush ribs  40  thus form impact absorbing elements that are designed to deform (i.e., be partially or substantially crushed) to at least partially absorb and dissipate the energy from the fractured coil spring portion if the coil spring  16  fractures. The first crush ribs  40  in one example have a thickness of preferably about 1 mm-3 mm, although it will be appreciated that this dimension may vary depending on various factors, including, but not limited to, the dimensions of the coil spring  16  and/or the cross sectional thickness of its coils. The second crush ribs  42  are designed to collectively form a circumferential plane that further help to ensure that the first crush ribs  40  do not “fold” or collapse too easily toward the base portion  26  when impacted by the broken portion of the coil spring  16 . In some instances it may occur that one or more of the second crush ribs  42  receive all or a majority of the impact force from a fractured coil spring. In summary then, both of the first and second crush ribs  40  and  42  cooperatively operate to absorb and dissipate the energy that is produced when the coil spring  16  fractures. 
         [0027]    Referring briefly to  FIG. 4 , the catcher  28  in this embodiment also may have a plurality of circumferentially spaced apart reinforcement ribs  28   b  formed on an outer surface  28   c  thereof. In this embodiment the reinforcement ribs  28   b  provide further structural strength to the catcher  28  and the lower spring seat  18  in general. It will also be noted that the thickness of each reinforcement rib  28   b  is preferably at least slightly greater than the thickness of each crush rib  40 . Furthermore, the thickness of each of the first and second crush ribs  40  and  42 , respectively, is preferably thinner than the thickness of the catcher  28  in order to help ensure that the crush ribs  40  and  42  deform first and absorb the energy from a coil spring fracture event. The reinforcement ribs  28   b  help to ensure that the catcher  28  has sufficient strength to catch and restrain a broken section of the coil spring  16 , without adding significant weight or bulk to the catcher. 
         [0028]    Referring to  FIG. 5 , another embodiment of the impact absorbing structures  38 ′ is shown. This embodiment is similar to the impact absorbing structures  38  as described above but incorporates a second crush rib  42 ′ which is thicker than a first crush rib  40 ′ of the structure. The increase in thickness of the second crush rib  42 ′ over the first crush rib  40 ′ may vary significantly, for example by 10%-100%, or possibly more Alternatively, the thickness of the first crush rib  40 ′ may be selected to be greater than the thickness of the second crush rib  42 ′. The precise thickness of each of the crush ribs  40 ′ and  42 ′ may be selected to best meet the needs of a particular application. However, it is anticipated that in some applications it may be desirable to provide the second crush rib  42 ′ with a slightly greater thickness than the first crush rib  40 ′, as shown in  FIG. 5 . The increased thickness, in some instances, may help to provide a plane of increased area that further helps absorb and arrest movement of a broken portion of the coil spring  16  in the event the coil spring fractures. 
         [0029]      FIG. 6  shows another embodiment of the impact absorbing structures  38 ″ in which the first crush rib  40 ″ includes an upper section  40   a ″ of one thickness, and a lower section  40   b ″ having an increased thickness. A second crush rib  42 ″ also has a thickness which is greater than the thickness of the upper section  40   a ″ of the first crush rib  40 ″, and in this example generally in accordance with the thickness of the lower section  40   b ″. Accordingly, this embodiment even further expands the surface area plane that the second crush rib  42 ″ forms to slow down, help absorb energy, and arrest movement of a broken portion of the coil spring  16 . 
         [0030]    Referring to  7 , another embodiment  34 ′ of the coil locating rib  34  shown. Coil locating rib  36  could likewise be constructed in an identical manner to coil locating rib  34 ′. Coil locating rib  34 ′ has been modified to include a radial portion  34   a ′ having a first portion  34   a   1  and a second portion  34   a   2 . Second portion  34   a   2  extends out to the wall portion  28  of the lower spring seat  18 . The second portion  34   a   2  thus further helps to reinforce the catcher  28 . 
         [0031]    Referring to  FIG. 8 , a plate  100  is shown in accordance with another embodiment of the present disclosure. The plate  100  is intended to be used with a modified version of the lower spring seat  18  which does not include the crush ribs  40  and  42 . Instead, impact absorbing structures formed by first crush ribs  102  and second crush ribs  104  are formed on a floor portion  106  of the plate  100 . The plate  100  is placed on the base portion  26  of the lower spring seat  18  before the spring  16  is assembled onto the lower spring seat  18 . The inside surface wall portion  28   a  of the catcher  28  has a diameter that is just slightly greater than the outer diameter of the floor portion  106  of the plate  100  so that the plate fits securely within the inner diameter of the catcher  28 . The first and second crush ribs  102  and  104  generally form an upwardly projecting, T-shaped, rib-like structure that may be integrally formed with the floor portion  106  of the plate  100 . Optionally, the floor portion  106  of the plate  100  may include one or more cutouts to allow the coil locating structures  32 - 36  to project therethrough, or alternatively the coil locating structures  32 - 36  may be formed on the floor portion  106  of the plate  100 . This configuration may also allow for slightly different material configurations to be used when manufacturing the lower spring seat  18  and the plate  100 , since these two components are independent from one another in this embodiment. 
         [0032]    It will be appreciated that the configuration and dimensions of the various embodiments of the impact absorbing structures  38  described herein may be varied considerably to tailor them to specific coil spring dimensions, spring rates, and other factors. The weight and/or type of vehicle that the strut-type damper  10  is being used with may also influence the number and precise configuration and/or placement of the impact absorbing structures  38 . 
         [0033]    The lower spring seat  18 , and particularly the construction of the catcher  28 , thus forms a means to significantly strengthen the catcher without significantly increasing its weight, dimensions or bulk, or cost of manufacture. Importantly, the catcher  28  of the present disclosure does not require any significant modifications to the construction of a coil spring or to any other portion of a strut-type damper. The entire lower spring seat  18 , catcher  28  and impact absorbing structures  38 ,  38 ′ or  38 ″ may be integrally formed as a single component from high strength plastic, from a composite or any other suitably strong, lightweight material. 
         [0034]    While various embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the present disclosure. The examples illustrate the various embodiments and are not intended to limit the present disclosure. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.