Abstract:
An isolation system includes a platform, a plurality of isolators for the platform, at least one actuator subsystem positioned to rigidly support the platform, and a controller subsystem configured to activate the actuator subsystem to rigidly support the platform in a first configuration, and otherwise deactivate the actuator subsystem for support by the plurality of isolators in a second configuration.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to vibration isolation. 
       BACKGROUND OF THE INVENTION 
       [0002]    Vibration isolation systems typically include a platform and a plurality of isolators often one in each corner of the platform. An isolator may include a piston on a diaphragm supporting the platform. A first (top) pressurized air chamber supports the diaphragm and a second (bottom) pressurized air chamber supplies air to the first chamber and acts as a reservoir. 
         [0003]    In some designs, stiff and soft modes of isolation are possible. Reasons to control the stiffness of the isolator include responding to loads or changes in loads on the platform. When the isolation platform is used to isolate a machine (such as a shaker) from the floor of a building, it can be desirable to adjust the stiffness of the system in real time based on the operation cycle of the machine. U.S. Pat. No. 6,123,312, for example, incorporated herein by this reference, shows a pressure regulator regulating the pressure in the second chamber based on the load on the platform. The second chamber is connected to the first chamber via an isolation controller which controls the gas flow rate from the second chamber to the first chamber. A control signal controls the isolation controller and thus the stiffness of the isolator. 
         [0004]    In another design, a valve allows air to flow from the second chamber to the first chamber via either high or low resistance coils in order to control the stiffness of the isolator. 
         [0005]    Other relevant prior art may include U.S. Pat. Nos. 4,796,873; 7,114,710; 4,531,699; 4,735,296; 5,061,541; 5,348,266 and 5,962,104, all of which are incorporated herein by this reference. 
       SUMMARY OF THE INVENTION 
       [0006]    Transition to the stiff mode of isolation is effected in an example of the subject invention by by-passing the bottom chamber providing more rapid pressurization of the top chamber to handle, for example, moving loads. 
         [0007]    In some examples, one more actuator subsystems are included to restrain movement of the isolator platform. 
         [0008]    In some examples of the invention, the natural frequency of the isolation platform is adjusted based on the frequency of a machine supported by the platform. 
         [0009]    In one aspect, an isolation system is featured. The system includes a platform, a plurality of isolators for the platform, at least one actuator subsystem positioned to rigidly support the platform, and a controller subsystem configured to activate the actuator subsystem to rigidly support the platform in a first configuration, and otherwise deactivate the actuator subsystem for support by the plurality of isolators in a second configuration. 
         [0010]    In one embodiment, the actuator subsystem may include a downward restraint actuator with an extendable and retractable piston under the platform and a frame supporting the actuator. The actuator subsystem may include a frame connected to an underside of the platform and an upward restraint actuator with an extendable and retractable piston configured to drive the frame downward. The actuator subsystem may be configured for horizontal restraint. The isolator may include a piston supported by a diaphragm in a housing and the horizontal restraint isolation subsystem is fixed to the piston and actuatable to lock the piston with respect to the housing. The housing may be fixed in a platform leg. Each horizontal restraint actuator subsystem may include pairs of opposing extendible and retractable pistons. There may be a downward restraint solenoid on each corner of the platform. There may be an upward restraint solenoid on each corner of the platform. There may be a horizontal restraint actuator in each platform leg. The controller subsystem may be configured to control said isolators in response to the configuration of the actuator subsystem. 
         [0011]    In another aspect, a method of restraining deflection of an isolation subsystem is featured. The method includes, in response to a signal, automatically restraining the platform at least vertically and at least against downward movement, in response to said signal, automatically restraining the platform horizontally, and isolating the platform otherwise vertically and horizontally.
       In one embodiment the method may include, in response to said signal, automatically restraining the platform vertically against upward movement.       
 
         [0013]    The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0014]    Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which: 
           [0015]      FIG. 1  is a schematic cross sectional view of a conventional isolator; 
           [0016]      FIG. 2  is a cross sectional view of the conventional isolator shown in U.S. Pat. No. 6,123,312; 
           [0017]      FIG. 3  is a schematic view of another conventional isolator; 
           [0018]      FIG. 4  is a schematic view of a fast response dual stiffness mode isolator in accordance with an example of the invention; 
           [0019]      FIG. 5  is a schematic top view showing the location of isolators as shown in  FIG. 4 , as well as various vertical restraint subsystems in accordance with the invention; 
           [0020]      FIG. 6  is a schematic view of a downward vertical restraint subsystem in accordance with an example of the invention; 
           [0021]      FIG. 7  is a schematic view of vertical upward restraint subsystem in accordance with an example of the invention; 
           [0022]      FIG. 8  is a schematic top view of an example of a horizontal restraint subsystem in accordance with the invention; and 
           [0023]      FIG. 9  is a schematic view showing an example of a resonance free isolation system in accordance with an example of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer. 
         [0025]      FIG. 1  shows a prior art isolator  10  for platform  12  with flexible diaphragm  14  supporting piston  16  itself supporting platform  12 . Top chamber  18  is pressurized by air from bottom chamber  20  as shown via conduit  22 . Supply air is directed to bottom reservoir chamber  20  via pressure regulator  24  with a lever  26  actuated by movement of platform  12 . 
         [0026]      FIG. 2  shows the design of U.S. Pat. No. 6,123,312 wherein isolation controller  30  controls the gas flow rate from bottom chamber  20  to top chamber  18  based on a control signal, from the moving speed of the operating machine above the platform. 
         [0027]    In the prior art design of  FIG. 3 , when valve  40  is open for a soft mode of isolation, supply air is directed from bottom chamber  20  to top chamber  18  via a short damping coil  21 . When valve  40  is closed for a stiff mode of operation, air is directed from bottom chamber  20  to top chamber  18  via longer damping coil  22 . 
         [0028]    In one preferred embodiment, a fast response dual stiffness mode isolator  60 ,  FIG. 4  features valve  62  connected to supply air (port B) from regulator  24  via T intersection  64 . Valve  62  is connected to top chamber  18  (port A) via short damping coil  68  such as an airline coil or similar type device and to bottom chamber  20  via conduit  70  (port C). Bottom chamber  20  is pressurized via long damping coil  72  between valve  62  and bottom chamber  20 . 
         [0029]    Top chamber  18  is pressurized in the soft mode of operation by activating valve  62  to close port B and to open port C. This may be the configuration of valve  62  when it is energized by a signal from controller  80 . Pressurized air now flows from chamber  20  through ports C and A of valve  62  to top smaller chamber  18 . 
         [0030]    By closing port C and opening port B of valve  62  in the stiff mode of operation (preferably by de-energizing valve  62 ), bottom chamber  20  is by-passed and supply air is directed to top chamber  18  via ports B and A and short damping coil  68 . At the same time, supply air is directed to bottom chamber  20  via long coil  72  to pressurize bottom chamber  20 . Other restriction methods and devices can be used in lieu of coil  72  and  68 . 
         [0031]    The control signal from controller  80  to solenoid valve  62  may be based on the output signal of the operation of the machine above the platform or from signals representing loads on and/or movement of platform  12  (using velocity sensors, accelerometers, and the like, for example). 
         [0032]    Uniquely, a restriction such as long damping coil  72  is in series between the other restriction such as short damping coil  68 . By diverting air flow through both restrictions and pressurizing chambers  18  and  20  simultaneously, top chamber  18  can provide the necessary reaction force to regain the original platform level position in a shorter time. A higher stiffness is provided due to the fact that damping chamber  20  is located at the end of the air supply line with no air flow through it when the isolator is in the stiff mode. 
         [0033]    In some examples, controller subsystem  80  further controls one or more actuator subsystems (e.g., rigid restraints) to restrain the platform vertically and/or horizontally. The controller subsystem may be a programmable logic controller, a computer, an application specific integrated circuit, or the like or a combination of these and like kinds of electronic devices interconnected by wiring and/or distributed and communicating wirelessly. 
         [0034]    In  FIG. 5 , platform  12  includes legs with an isolator  60 ′ in each corner. Isolator  60 ′ may be configured as discussed above with respect to  FIG. 4 , may be a more conventional isolator with a single mode of operation, and/or modified as discussed with respect to  FIG. 7  discussed below wherein each isolator is equipped with a horizontal restraint actuator subsystem. 
         [0035]    Also shown in this example at each corner is a downward restraint actuator subsystem  100  which prevents a platform corner from moving downward. Optionally an upward restraint actuator subsystem  102  and upward restraint actuators  102   c  and  102   d  is also provided at each corner to prevent a platform corner from moving upwards. Typically, a machine on the platform sends a signal to the controller indicating that the load is about to move. In response, the controller sends the appropriate signals to downward restrain actuator subsystem  100  and upward restraint actuator subsystem  102 . There respective actuators prevent the platform from moving up or down. A similar signal may be sent to the horizontal actuator subsystem to prevent horizontal movement of the platform. The controller also signals the isolator subsystem to bleed the isolators that the load is moving away from and to fill the isolators that the load is moving towards. 
         [0036]    In but one example, the controller in response to a signal from a payload operation on platform  12 , activates downward restraint actuators  100   a  and  100   b  and upward restraint actuators  102   c  and  102   d  and all four horizontal restraint actuators. Examples of high loads triggering the activation of the restrainers include a robot art on platform  12  moving a heavy load. If the load changes to a first threshold, the controller subsystem may cause one or more isolator  60  to operate in the stiff mode as described above with respect to  FIG. 4 . If the load changes to a second threshold greater than the first threshold, one or more restraint actuators can be activated. 
         [0037]    In  FIG. 6 , downward restraint actuator subsystem  100   b  includes frame  110  with plate  112  supporting load sensor  114  itself supporting sliding plate  116  on rails  118  fixed to plate  112 . The sliding plate supports pneumatic actuator  120  with extendible and retractable piston  122  under platform  12 . Controller subsystem  80 , upon detecting a predetermined load from sensor  114  and/or upon receiving a signal from the machine on the platform, activates locking solenoid  124  to direct air to pneumatic actuator  120  driving piston  122  upward against the underside of platform  12 . The appropriate isolators are then filled or bleed. When the load is no longer sensed, the piston is retracted via signal from controller subsystem  80  delivered to closed solenoid  124 . 
         [0038]    As noted above, controller subsystem  80  may also control isolator  60 ′ via valve  62 . In one example, the bottom chamber of isolator  60 ′ can be charged while piston  122  is extended. 
         [0039]      FIG. 7  depicts an example of an actuator subsystem configured for vertical restraint of a platform moving upward. The frame  131  includes fixed plate  130  supported by fasteners such as those shown at  132   a  and  132   b . Rods such as rods  134   a  and  134   b  are interconnected between the bottom of platform  12  and sliding plate  136 . Sliding plate  140  moves up and down with sliding plate  136  and is guided by rails such as rails  142   a  and  142   b . Load sensor  114  is disposed between sliding plates  140  and  136  and pneumatic actuator  120  with piston  122  is disposed between sliding plate  140  and fixed plate  136 . 
         [0040]    When platform  12  lifts up, load sensor  114  detects an increased force and sends a signal to controller subsystem  80  which then actuates pneumatic actuator  120  piston  122  which pushes sliding plates  140  and  136  down thus pulling the rods and platform  12  down. The machine on the platform may also send a signal to controller subsystem  80  to actuate pneumatic actuator  120 . 
         [0041]      FIG. 8  depicts an example of an actuator subsystem configured for horizontal restraint. Opposing pairs of pneumatic actuators  200   a  and  200   b  and  200   c  and  200   d  are located in frame block  202  and each have an extendible and retractable piston  204   a ,  204   b ,  204   e , and  204   d.    
         [0042]    Block  202  is preferably partially within or coupled to the top of piston  16 ,  FIG. 4 , between it and the underside of the platform. The actuator pistons  204 , when extended, press on a structure coupled to the platform leg such as clamping ring  206 . 
         [0043]    When controller subsystem  80  activates locking solenoid  208 , air is supplied to actuators  200   a - 200   d  and pistons  204   a - 204   d  extend arresting horizontal movement of the piston and thus the platform. When the pistons retract by closing solenoid  208 , normal isolation resumes. Typically, each platform leg isolator is equipped with such a horizontal restraint system automatically activated when the vertical restraint subsystem is activated. 
         [0044]      FIG. 9  shows an isolation subsystem with pneumatic isolator  60  (See, e.g.,  FIG. 4 ), vertical restraint actuator subsystem  100  (See, e.g.,  FIGS. 6 and 7 ), and a horizontal restraint actuator subsystem  200  (See, e.g.,  FIG. 8 ). Platform  12  supports machine  300  (e.g., a shaker) controlled by controller  302  via signals to current amplifier  304 . 
         [0045]    Controller subsystem  80  (which may include digital controller  80   a  and frequency monitoring device  80   b  with double integration electronic circuits) receives and is responsive to a signal representing the frequency of machine  300 . 
         [0046]    Controller subsystem  80  is configured to adjust isolator  60  between the soft and stiff modes via controller valve  62  depending on the frequency of machine  300 . For example, the natural frequency of the platform and isolators in the soft mode is known as is the natural frequency of the platform and isolators in the stiff mode of operation. 
         [0047]    If the frequency of machine  300  approaches or is near the natural frequency of the platform in the soft mode, controller subsystem  80  activates valve  62  to switch isolator  60  to the stiff mode. At all other times, controller  80  actuates valve  62  to switch isolator  60  to the soft mode. In this way, resonance magnification is avoided. 
         [0048]    In this particular example, a first channel of digital logic control unit  80   a  receives a signal from shaker controller  302 . The second channel of the digital logic control unit receives a signal from the double integration circuit in frequency monitoring device  80   b . Both channels of digital logic control unit  80   a  may include analog to digital data collection cards. The absolute value of the amplitudes of the two signals (input and output) of the double integers should have a precise ratio equal to the square of the angular frequency of the by-passed shaker controller input signal. Through this process, unit  80   a  is programmed to determine the frequency of the input signal instantly and to engage or disengage the dual modes or rigid support mode of the isolation system. The ratio of the angular frequencies should be the same power of the difference of the order difference in the integration device. 
         [0049]    Controller subsystem  80  may also be configured to “lock out” the system (e.g., rigidly support the platform) by activating solenoid  124  and/or solenoid  208  to engage the vertical and/or horizontal restraint actuators if the frequency of machine  300  reaches a predetermined frequency and/or amplitude which could adversely affect the testing process or damage the system and/or its components and to prevent resonance magnification. 
         [0050]    Frequency monitoring device  80   b  preferably includes an electronic double integration circuit which receives a signal from the shaker controller  302  and identifies the shaker&#39;s frequency of operation. Digital logic control unit  80   a  receives a signal from frequency monitoring device  80   b  provided to a first channel of digital logic control unit  80   a  which has two or more channels of analog to digital data collection cards. Controller  80   a  via second channel receives a signal from a double integration circuit in the frequency monitoring device  80   b . The absolute value of the amplitude of the two signals should have a precise ratio equal to the square of the angular frequency of the by-passed input signal, thus through this process unit  80   a  is programmed to determine the frequency of the input signal instantly and to engage and disengage the dual/multiple mode or rigid support mode of the isolation system. The ratio for the angular frequency should be same power of the difference of the order difference in the integration device. 
         [0051]    Controller  80  may also be programmed to “lock out” the system by activating solenoid  124  and/or solenoid  208  to engage the vertical and/or horizontal restraint actuators if the frequency of machine  300  reaches a predetermined frequency and/or amplitude which could jeopardize the testing process or damage the system and/or its components and to prevent resonance magnification. 
         [0052]    Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments. 
         [0053]    In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant can not be expected to describe certain insubstantial substitutes for any claim element amended. 
         [0054]    Other embodiments will occur to those skilled in the art and are within the following claims.