Abstract:
An apparatus and method to isolate downhole components within a downhole tool from shock and vibration typically experienced during handling and use of the downhole tool. The apparatus and method include a series of interlocking hooks and loops that are bondable to the downhole component and dampingly secure the downhole component within the downhole tool. The material comprising the interlocking hooks and loops is a high temperature material whose performance is not affected by high temperatures.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates generally to the field of isolating devices from mechanical dynamics. More specifically, the present invention relates to a method and apparatus to provide damping for components sensitive to shock and vibration.  
         [0003]     2. Description of Related Art  
         [0004]     The recent past has seen a ubiquitous implementation of electrical processing devices and equipment containing data processing components such as printed circuit boards, integrated circuits, resistors, capacitors and the like. These devices can now be found in automobiles, motorcycles, aircraft, and ships. They are also in use in other devices such as computers, microprocessors, electrical controllers, and sensors. In many of the applications where electrical processing devices are implemented, they are subjected to some type of shock and vibration. While the electrical processing devices do function basically as conduits or switches for electrical signals, they are still primarily formed of a solid structure. As such these devices are subject to failure or diminished functional capacity when they experience some types of vibration and/or shock. To rectify this situation, vibration and shock dampers have been suggested in the past. These include mechanical springs, rubber dampers, diaphragms, resilient supports, and elastomer compounds. Examples of these devices can be found in Singh, U.S. Pat. No. 6,130,284, Lee et al. U.S. Pat. No. 6,621,694, Mintzlaff, U.S. Pat. No. 4,893,210, Yamashita, U.S. Pat. No. 6,354,575, Dean U.S. Pat. No. 4,429,348, Parson U.S. Pat. No. 6,473,309, and Heinrich et al., U.S. Pat. No. 4,382,587.  
         [0005]     Currently many downhole tools used in the exploration and production of hydrocarbons employ sensitive electrical processing devices referred to herein as downhole components. The downhole components include without limitation electrical devices, electrical components, electrical circuits, printed circuit boards, downhole sensors, cooling components, antennas, receivers. Downhole tools also often experience high shock and vibration conditions either during use within a wellbore, or during handling after they have been assembled and prior to use within a wellbore. Often times the shock or vibration can damage the downhole components thereby rendering the component inoperable or ineffective. Further, the shock and vibration during use can cause the downhole component to provide erroneous data, this is especially so when the downhole component is a sensor monitoring data downhole for later analysis. The harsh downhole conditions introduce another environmental factor that must be considered, and that is the high temperature, which can sometimes exceed 200° C. Accordingly, any damping device or element used in a downhole application must be able to function relatively consistently at the expected range of operating temperatures.  
         [0006]     Various attempts have been made to lessen the shock and vibration of mechanical dynamics experienced by downhole components during handling and use of downhole tools. These attempts generally involve attempting to dampen the shock and vibration applied to the downhole components with some type of an elastomer. For example, rubber O-rings have been employed to isolate downhole components from shock and vibration experienced by a downhole tool. Additionally, downhole components have been seated within the downhole tools on visco-elastomeric materials in an effort to minimize the shock and vibration imparted to the downhole component. However these static suspension systems can often amplify the effects of shock induced vibration instead of minimizing the effect. Therefore, there exists a need for a device and method of isolating downhole components of a downhole tool from the damaging and data altering effects of shock and vibration encountered during the use, handling and assembly of the downhole tool.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     The present invention includes a damping system useful to isolate a device from mechanical dynamics from a surface comprising a first quantity of damping material having a mating side and a connecting side, wherein the mating side of the first quantity of shock absorbing material comprises a multiplicity of outwardly extending members and a second quantity of damping material having a mating side and a connecting side wherein the mating side of the second quantity of damping material comprises a multiplicity of outwardly extending members. The first quantity of damping material can be affixed to the device and the second quantity of damping material can affixed to the surface, where the multiplicity of outwardly extending members of the first damping material mate with the multiplicity of outwardly extending members of the second damping material.  
         [0008]     At least a portion of the outwardly extending members of the first quantity of damping material should be in frictional rubbing contact with at least a portion of the outwardly extending members of the second quantity of damping material. In an alternative embodiment of the present invention, the outwardly extending members of the first quantity of damping material are comprised of a series of hooks and the outwardly extending members of the second quantity of damping material are comprised of a series of loops. Optionally, the outwardly extending members of the first quantity of damping material can be comprised of a series of loops and the outwardly extending members of said second quantity of damping material can be comprised of a series of hooks. Alternatively, the outwardly extending members of the first quantity of damping material can be comprised of a multiplicity of fingers and the outwardly extending members of the second quantity of damping material can be comprised of a multiplicity of fingers.  
         [0009]     The surface area of the first smooth surface is preferably substantially equal to the surface area of the connectable portion of the device. The device can be selected from the group consisting of electrical circuit boards, avionics, data recording devices, electrical receivers and transmitters, sensors, and printed circuit boards. The damping material should be suitable for high temperature applications and suitable for use within a wellbore.  
         [0010]     The present invention includes a method of isolating a device having a connectable area from mechanical dynamic forces. The method of the present invention comprises securing the connecting side of a first quantity of damping material to a portion of the device, securing the connecting side of a second quantity of damping material to a surface, and mating the mating side of the first quantity of damping material with the mating side of the second quantity of damping material. The present method can further comprise securing the connecting side of a first quantity of damping material to a portion of the shock sensitive device, wherein the portion has a surface area that is substantially the same as the surface area of the connectable area of the device. Wherein the mating side of the first quantity of damping material can be comprised of a series of hooks and the mating side of said second quantity of damping material can be comprised of a series of loops. Optionally, the mating side of the first quantity of damping material can be comprised of a series of loops and the outwardly extending members of the second quantity of damping material can be comprised of a series of hooks. Also, the mating side of the first quantity of damping material can be comprised of a multiplicity of fingers and the mating side of the second quantity of damping material can be comprised of a multiplicity of fingers.  
         [0011]     The device for use with the method can be selected from the group consisting of electrical circuit boards, avionics, data recording devices, electrical receivers and transmitters, sensors, and printed circuit boards. The damping material should be suitable for high temperature applications as well as suitable for downhole applications. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0012]      FIG. 1   a  depicts a side view of one embodiment of a damping material in combination with a shock sensitive device.  
         [0013]      FIG. 1   b  depicts a side view of one embodiment of a damping material.  
         [0014]      FIG. 2   a  illustrates in side view one embodiment of a damping strip.  
         [0015]      FIG. 2   b  illustrates in side view one embodiment of a damping strip.  
         [0016]      FIG. 2   c  illustrates in side view one embodiment of a damping strip.  
         [0017]      FIG. 3  shows in perspective view a downhole component securable with one embodiment of the present invention.  
         [0018]      FIG. 4  displays a case and sensor having damping material attached thereto.  
         [0019]      FIG. 5  illustrates a cross sectional view of a sensor having damping material.  
         [0020]      FIG. 6  depicts an embodiment of the present invention in an overlap configuration. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     With reference to the drawing herein, an embodiment of the present invention is illustrated in a side view in  FIG. 1 . A device  12  is shown releaseably secured to a surface  10  by a pair of damping strips  18 . The device  12  can be any device susceptible to being damaged or adversely affected by mechanical dynamic forces, such as shock, vibration and shock or vibration. Examples of such devices include without limitation electrical components, such as electrical circuit boards, avionics, data recording devices, electrical receivers and transmitters, and sensors. The surface  10  therefore can represent the structure or base on which the device  12  is typically secured. Examples of possible foundations  10  include electrical component mounting boards found in computers, bulkheads/shelves in aircraft, mounting surfaces for downhole components within downhole tools, and other securing surfaces for mechanically dynamic sensitive devices. Each damping strip  18  is comprised of a damping material that has a connecting side  15  and a mating side  13 .  
         [0022]     The mating side  13  of each damping strip  18  should have a multiplicity of outwardly extending members  11  formed thereon. The outwardly extending members  11  should be capable of cooperatively mating with the members  11  formed on the mating side  13  of a corresponding damping strip  18 . Cooperative mating includes the capability of these members  11  on corresponding pieces of damping material to be releasably joined to one another, as well as the ability to absorb and dampen any mechanical dynamics imparted onto these members when mated to each other. Mechanical dynamics include, shock, vibration, and the combination of shock and vibration together. As can be seen in  FIG. 1 , mating of the damping material involves urging together the mating sides  13  of two corresponding pieces of damping material (or two damping strips  18 ) such that the corresponding upwardly extending members  11  mate together in frictional contact. Thus when the damping strips  18  are mated, the members  11  of the damping strips  18  are in frictional rubbing contact. This mated frictional rubbing contact between the members absorbs and dampens the mechanical dynamics experienced by one of the damping strips  18 . Therefore when two damping strips  18  of the present invention are mated, they are secured to one another while still being isolated from the mechanical dynamics experienced by the other.  
         [0023]     The connecting side  15  of each damping strip  18  should be capable of being secured to either a device  12  or a surface  10 . The connecting side  15  should be a mostly even and level surface for attachment to a device  12  or a surface  10 . Secure attachment of the connecting side  15  of the damping strip  18  can involve adhesives such as RTV materials, glue, or epoxy; other securing alternatives include mechanical fastening, such as bolts, screws, rivets, pins, and the like.  
         [0024]     Accordingly, while the damping strips  18  of the present invention can be mated or secured to one another, either of the damping strips  18  can be isolated from mechanical dynamics imparted upon the other damping strip  18 . As such, the damping strips  18  of the present invention provide the capability of releasably securing a device  12  to the surface  10  while at the same time isolating the device  12  from the mechanical dynamics experienced by the surface  10 .  
         [0025]     As shown in  FIG. 2   a,  it is preferred that the outwardly extending members  11  disposed on the damping material be comprised of a series of hooks  25  and loops  24 , such as VELCRO®. The hooks  25  and loops  24  are provided on the mating side  13  of a pair of opposing damping strips  18 . Joining the surfaces having the hooks  25  and loops  24  disposed thereon provides a releasable bond and a mechanical dynamic absorbing capability. Alternatively, as shown in  FIG. 2   b,  the outwardly extending members  13  of the damping material can be comprised of a multiplicity of fingers  17 . When the damping strips  18  having a multiplicity of fingers  17  is mated, the fingers  17  from each opposing damping strip  18  can be in frictional and rubbing contact. This frictional and rubbing contact between the opposing fingers  17  has a mechanical dynamic absorption capability, such that any device  12  secured with the damping strip  18  having the multiplicity of fingers  17  can be isolated from the damaging and deleterious effects of mechanical dynamics.  
         [0026]     An alternative embodiment of the present invention is shown in an exploded view in  FIG. 3 . The embodiment of the invention of  FIG. 3  includes a series of damping strips  18  attachable to a downhole component and chassis  26 . In the embodiment of  FIG. 3 , the downhole component shown is a printed circuit board  20  (PCB). The chassis  26  is shown having two largely cylindrical ends  27  connected by the sides  28  of the chassis  26  that extend along the axis of the chassis  26 . A base  29  is formed within the chassis  26  that is largely perpendicular to the sides  28  and connects the ends  27  of the chassis  26 . A trough  32  is formed along the length of the chassis  26  bounded along its perimeter by the sides  28  and the ends  27  and bounded on its bottom by the base  29 .  
         [0027]     In the embodiment of  FIG. 3 , it is preferred that the damping strip  18  adhered to the base  29  be comprised of a series of hooks  25  and loops  24 . More specifically, the series of interlocking hooks  25  should be disposed on its mating side. Likewise, it is preferred that the damping strip  18  secured to the downhole component include a series of interlocking loops  24  on its mating side. It should be pointed out that the present invention is not limited to use to the type of chassis  26  illustrated in  FIG. 3 , but can include any type of currently known or later developed mounting device used to secure a downhole component within a downhole tool.  
         [0028]     As previously noted, the embodiment of the invention of  FIG. 3  is shown in an exploded view. Thus while the damping strip  18  of  FIG. 3  is shown to be separate from the PCB  20 , once assembled the shock absorbing strip  18  should be securedly connected to the bottom of the PCB  20  on its smooth side, preferably with an RTV type adhesive. Further assembly of the present invention involves mating opposing damping strips  18  on their mating side after they have been respectively securedly connected to the base  29  and the PCB  20 . Care should be taken while mating the opposing damping strips  18  when the mating side of the damping strips  18  includes hooks  24  and loops  25 . It is important that a proper tolerance exists between the hooks  24  and loops  25  to isolate the downhole component from damaging forces. The PCB  20  (or any other like downhole component) will not be isolated from mechanical dynamics if the hooks  25  and loops  24  are too loosely or too tightly mated. It is well within the capabilities of those skilled in the art to determine the proper tolerance between the hooks  24  and loops  25  without undue experimentation.  
         [0029]     As shown in  FIGS. 4 and 5 , the present invention can also be used to secure cylindrically configured downhole components within a case or housing that are secured within a downhole tool. Here an enclosure  33  is shown comprising a hemispherical case top  35  and a hemispherical case bottom  37 , where the case top  35  and the case bottom  37  each is hollowed out along their respective axis to receive a cylindrical sensor  39  therein. Inner damping material  40  is affixed to the outer surface of the cylindrical sensor  39  on its smooth side  45  such that its mating side  47  is projecting outward from the cylindrical sensor  39 . Corresponding outer damping material  42  can be wrapped around the inner damping material  40  with its mating side  49  projecting inward to ward the mating side  47  of the inner damping material  40 . The travel of the damping absorbing material  42  can exceed 360° thereby providing an overlap  53 . Upon attaching both the inner and outer damping material ( 40 ,  42 ) to the sensor  39 , the entire assembly can be stowed within the enclosure  33 . The presence of the corresponding inner and outer damping materials ( 40 ,  42 ) within the enclosure  33  can isolate the cylindrical sensor  39  from mechanical dynamics imparted onto the enclosure  33 .  
         [0030]      FIG. 6  illustrates an alternative manner of applying the damping strips  18  to a device susceptible to damage from shock and/or vibration, such as a PCB  20 . Here multiple damping strips  18  are wrapped around the PCB  20  and the mating sides of the individual damping strips  18  face the mating side of the next adjacent damping strip  18 . While the mating components of  FIG. 6  comprise hooks  14  and loops  17 , the mating sides of this embodiment of the invention could include any of the fastening surfaces herein disclosed. The wrapped device  30  is securable to a base by adhesive applied to the smooth surface  15  of one of the damping strips  18 .  
         [0031]     Alternatively, the inner damping material  40  can be attached to the sensor  39  and the outer damping material  42  can be secured to the inside of the case top  35  and case bottom  37 . Arranging the inner and outer damping materials ( 40 ,  42 ) in this fashion allows the sensor  39  to be secured within the case  33  as well as being protected against mechanical dynamic forces. The damping material can be comprised of the hook  25  and loop  24  arrangement of  FIG. 2   a,  the multiplicity of fingers  17  of  FIG. 2   b,  as well as the ball tipped fingers of  FIG. 2   c.    
         [0032]     The amount of coverage over the connectable area by the damping strips  18  is also important. The connectable area refers to the area on the device  12  on which damping strips  18  can be connected. For example, when the downhole component is a PCB  20 , its connectable area is primarily the area on the bottom side of the PCB  20 . When the downhole component is a cylindrical sensor  39 , the connectable area is largely equal to the exterior radial surface along the axis of the cylindrical sensor, and does not include the ends of the sensor. With regard to the PCB  20  and like items, in order to effectively protect the PCB  20  against mechanical dynamics, the area of the damping strips  18  adhered to the PCB  20  (the coverage area) should be substantially the same as the area of the connectable area. However it has been found that other types of components may require a different amount of coverage area depending on how robust the component is and the physical parameters, such as the component&#39;s mass, its moment of inertia, and stiffness. Other variables include the type of damping strips  18  as well as temperature. The use of a vibrational test device, such as a shaker, may be employed to tune the component and to ascertain the required coverage area of a specific component.  
         [0033]     Due to the high temperatures that can be experienced downhole, the damping strips  18  should be comprised of a high temperature material. For the purposes of the present invention, high temperature materials include those capable of withstanding from about 150° C. to about 175° C. without experiencing any noticeable reduction in performance capability. NOMEX® is one such material that meets the performance criteria necessary to operate in high temperature downhole conditions. Accordingly in an exemplary example of the present invention, the shock absorbing strips  18  can be comprised of NOMEX® or a like material.  
         [0034]     The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, in addition to the hooks and loops and multiplicity of opposing fingers above described, the damping strip  18  can also contain a series of hooks and hooks, loops and loops, fingers and hooks, or fingers and loops. These variations and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.