Patent Publication Number: US-2007119297-A1

Title: Linear hydraulic amplifier

Description:
REFERENCE TO RELATED APPLICATIONS  
      This application claims an invention which was disclosed in Provisional Application No. 60/701,204, filed Jul. 21, 2005, entitled “LINEAR HYDRAULIC AMPLIFIER”. The benefit under 35 USC §19(e) of the United States provisional application is hereby claimed, and the aforementioned application is hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The invention pertains to the field of linear positioners. More particularly, the invention pertains to a linear hydraulic amplifier positioner.  
      2. Description of Related Art  
      Hydraulic amplifiers of the prior art are often used to output an amplified force based on a force received.  
      One example of a hydraulic force amplifier is Warnecke et al.&#39;s U.S. Pat. No. 4,516,470 which discloses an unbalanced hydraulic valve assembly. The assembly has a housing with a bore which receives an amplifier piston. One end of the bore is closed by a plug and a pressure piston and the opposite end of the bore is closed by seals and a separating piston. The amplifier piston consists of an outer guide sleeve, an inner control sleeve, and a control plunger. The outer guide sleeve and the inner control sleeve each have two control ports that may line up depending on the position of the control plunger. The control plunger is connected at one end to a reaction piston attached to a brake pedal and to a piston base member attached to a separating piston at the other end of the control plunger. The separating piston is connected to the brake master cylinder. A fluid chamber is formed between the housing and the amplifier piston and leads to a return conduit or sump. Another fluid chamber is formed between the amplifier piston and the end of the bore sealed with the plug and leads to a pressure conduit or pressurized supply. When pressure is applied to the reaction piston, the control plunger is moved to a position such that at least one of the control ports opens, allowing fluid communication between the pressure conduit and the fluid chamber formed between the amplifier piston and the end of the bore sealed with the plug. Likewise, as the amplifier piston continues to move towards the separating piston, a second control port opens and fluid in the chamber formed between the housing and the amplifier piston exits through the return conduit.  
      Another example of a hydraulic amplifier is Leineweber et al.&#39;s U.S. Pat. No. 4,379,423, which discloses a housing provided with pressure and return conduits, an amplifier piston and a control slide. The piston is slidably received in a bore of the housing and has a blind bore for receiving the control slide. The piston and the control slide move together as a unit, free of pressure equalization. The unit has two sets of passages for selectively placing a face of the piston into communication with the pressure and return conduits, depending on the position of the slide in the bore of the piston.  
      All of the above examples of prior art hydraulic amplifiers require hydraulic pressure and return conduits. Therefore, there is a need for an amplifier device that is self-contained.  
     SUMMARY OF THE INVENTION  
      In a first embodiment, a piston is positioned by a vibrational work piece, establishing a position set point of the vibrational work piece relative to a stationary work piece or hollow sleeve. The piston, when acted upon by oscillatory vibrations of the vibrational work piece, moves towards the position set point with energy provided by cyclical vibrations of the vibrational work piece. The movement of the piston selectively directs fluid to flow from a first chamber to a second chamber and vice versa, moving the control sleeve relative to the piston, such that the position set point is obtained when the piston is centered or at null position within the control sleeve. The vibrational work piece may be moved relative to the stationary work piece.  
      In another embodiment, the piston is positioned by some external means, preferably a small electric actuator, a vacuum source, or solenoid, establishing a position set point of the vibrational work piece relative to the stationary work piece. When the piston is acted upon by oscillatory vibrations, the piston will move towards the position set point with energy provided by the cyclical vibrations. The movement of the piston selectively directs fluid to flow from a first chamber to a second chamber or vice versa, moving the control sleeve and in this case, the vibrational work piece relative to the piston, such that the position set point is obtained when the piston is centered or at null within the control sleeve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a positioner of a first embodiment in a first position used with a tensioner.  
       FIG. 2  shows a positioner of a first embodiment in a second position used with a tensioner.  
       FIG. 3  shows a positioner of a first embodiment in a third position used with a tensioner.  
       FIG. 4  shows a positioner of a second embodiment in a first position.  
       FIG. 5  shows a positioner of a second embodiment in a second position.  
       FIG. 6  shows positioner of a second embodiment in a third position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The positioner of the present invention utilizes vibrational energy for force amplification. The positioner may be used in any actuation system that has a cyclical force that is at least partially reversed. The positioner of the present invention does not need an external power source since oil is circulated internally to the positioner, which is self-contained.  
      In a first embodiment, shown in  FIGS. 1 through 3 , the positioner  101  is used with a vibrational work piece, such as a tensioner arm  114 . The positioner has a hollow sleeve  100  fixed to the engine block  103  or a stationary piece. The hollow sleeve has two open ends for slidably receiving a control sleeve  102 . The control sleeve  102  has multiple passages or ports  111   a ,  111   b ,  111   c ,  111   d  defined by control sleeve portions  102   a ,  102   b ,  102   c ,  102   d . Port  111   a  is defined between control sleeve portions  102   a  and  102   b . Port  111   b  is defined between control sleeve portions  102   b  and  102   c . Port  111   c  is defined between control sleeve portions  102   c  and  102   d . Port  111   d  is defined between control sleeve portions  102   d  and  102   e . The length of the control sleeve  102  is greater than the length of the hollow sleeve  100 , and the control sleeve portion  102   e  at one end is only partially received within the hollow sleeve  100 . A tab  102   f  formed on the control sleeve portion  102   e  acts as a stop and prevents the control sleeve  102  from sliding too far the left in the figures. The control sleeve  102  slidably receives a piston  104 . The piston  104  and the control sleeve  102  close off the two open ends of the hollow sleeve  100 , forming fluid chambers  116   a ,  116   b.    
      The piston  104  includes a plurality of lands  104   a ,  104   b ,  104   c , and  104   d . The land  104   d  extends a length beyond the hollow sleeve  100  and the control sleeve  102  and has a flat portion  104   e , which contacts the vibrational work piece  114 , which is shown as a tensioner arm in  FIGS. 1 through 3 . A central bore  107  runs a portion of the length of the piston  104 . Within the central bore  107  are check valves  105 ,  106 , allowing fluid to flow in one direction and blocking the flow of fluid in an opposite direction through the bore  107 . Extending from the bore  107  to fluid chambers  116   a  and  116   b  are a first passage  108 , a central passage  109 , and a second passage  110 , defined by the lands  104   a ,  104   b ,  104   c , and  104   d  of the piston. The first passage  108  is defined between lands  104   a  and  104   b . The central passage  109  is defined between lands  104   b  and  104   c . The second passage  110  is defined between lands  104   c  and  104   d . When the passages  108 ,  109  and  110  are aligned with the ports  111   a ,  111   b ,  111   c , or  111   d , the first passage  108  connects the bore  107  in the piston  104  to the first fluid chamber  116   a , the central passage  109  connects the bore  107  in the piston  104  to the first fluid chamber  116   a  or the second fluid chamber  116   b , and the second passage  110  connects the bore  107  in the piston  104  to the second fluid chamber  116   b . A plug  115  is present at the end of land  104   a  to seal off the end of the bore  107 .  
      A connecting spring  112  is present between the tab  102   f  of the control sleeve  102  and the flat portion  104   e  of the piston land  104   d , linking the motion of the piston  104  with the control sleeve  102 . The central position or null position of the piston  104  relative to the fixed hollow sleeve  102  is based on the connecting spring resting point.  
      A spring  113  is also present within the first fluid chamber  116   a  between the hollow control sleeve  102  and control sleeve portion  102   b  for preventing the control sleeve  102  from bottoming out and for aiding in returning the control sleeve  102  to a central position.  
      The first fluid chamber  116   a  is separated from the second fluid chamber  116   b  formed between the hollow sleeve  100  and the control sleeve  102  and piston  104  by control sleeve portion  102   c  and check valve  105  in the bore  107  of the piston  104  in the central position shown in  FIG. 1 . The second fluid chamber  116   b  is separated from the first chamber  116   a  formed between the hollow sleeve  100  and the control sleeve  102  and piston  104  by control sleeve portion  102   c  and check valve  106  in the bore  107  of the piston  104  in the central position or null position shown in  FIG. 1 .  
      In this embodiment, the piston  104  is positioned by the vibrational work piece  114 , establishing a position set point of the vibrational work piece  114  relative to the stationary work piece or hollow sleeve  102 . The piston  104 , when acted upon by oscillatory vibrations of the vibrational work piece  114 , will move towards the position set point with energy provided by cyclical vibrations of the vibrational work piece  114 . The movement of the piston  104  selectively directs fluid to flow from a first chamber  116   a  to a second chamber  116   b  and vice versa, moving the control sleeve  102  relative to the piston  104  such that the position set point is obtained when the piston  104  is centered or at null position within the control sleeve  102 .  
       FIG. 1  shows the piston  104  in a central or null position relative to the hollow sleeve or stationary piece  103 . In this position, fluid is prevented from moving from the first fluid chamber  116   a  to the second fluid chamber  116   b  or vice versa. The first passage  108  is aligned with control sleeve port  111   a , however, fluid is prevented from entering and traveling through the bore  107  in the piston  104  from the first passage  108  by check valve  105 . The central passage  109  is blocked by control sleeve portion  102   c . The control sleeve portion  102   c  also prevents fluid from traveling from the first chamber  116   a  to the second chamber  116   b  and vice versa. The second passage  110  is aligned with control sleeve port  111   d , however, fluid is prevented from entering and traveling through the bore  107  in the piston  104  from the second passage  110  by check valve  106 . The force of the connecting spring  112  and spring  113  is substantially equal to the force exerted by the vibrational work piece  114 .  
      In  FIG. 2 , the force of the vibrational work piece  114  is less than the spring force of the connecting spring  112 , establishing a position set point of the vibrational work piece  114 . The piston  104  is moved towards the tensioner arm, biasing the tensioner arm  114  in the Figure, towards the chain  117 . In order to recenter the piston  104  relative to the hollow sleeve  100  and obtain the position set point, fluid circulates from the second chamber  116   b  to the first chamber  116   a . Prior to recentering of the piston  104 , control sleeve ports  111   a ,  111   c , and  111   d  are open and control sleeve port  111   b  is blocked by piston land  104   b . Control sleeve port  111   c  is open to the central passage  109 , control sleeve port  111   d  is open to the second passage  110 , and control sleeve port  111   a  is open to the first passage  108 . Fluid in the second chamber  116   b , due to the movement and position of the piston  104 , flows from the second chamber  116   b  through the control sleeve port  111   c  and central passage  109  to the bore  107  in the piston  104 . From the central bore  107 , fluid flows through check valve  105  into the first passage  108  and to the first chamber  116   a . The movement of the fluid from the second chamber  116   b  to the first chamber  116   a  moves the control sleeve  102 , towards the tensioner arm  114 , following the piston  104 , resulting in the piston being in a centered position, relative to the stationary piece or hollow sleeve  100  as shown in  FIG. 1 , obtaining the position set point and in this case, moving the vibrational work piece  114  relative to the stationary piece  103 . With the control sleeve  102  following the piston position  104 , the vibrational force of the vibrational work piece  114 , for example the tensioner arm  114 , is amplified.  
      In  FIG. 3 , the force of vibrational work piece  114  is greater than the spring force of the connecting spring  112 , establishing a position set point of the vibrational work piece  114 . In this example, the piston  104  is moved away from the tensioner arm  114  and chain  117 . In order to recenter the piston  104  relative to the hollow sleeve  100  and obtain the position set point, fluid circulates from the first fluid chamber  116   a  to the second fluid chamber  116   b . Prior to recentering of the piston  104 , control sleeve ports  111   a ,  111   b , and  111   d  are open and control sleeve port  111   c  is blocked by piston land  104   c . Control sleeve port  111   b  is open to the central passage  109 , control sleeve port  111   a  is open to the first passage  108 , and control sleeve port  111   d  is open to the second passage  110 . Fluid in the first chamber  116   a , due to the movement and position of the piston  104 , flows from the first chamber  116   a  through the control sleeve port  111   b  and the central passage  109  to the bore  107  in the piston  104 . From the central bore  107 , fluid flows through check valve  106  into the second passage and the second chamber  116   b . The movement of the fluid from the first chamber  116   a  to the second chamber  116   b , moves the control sleeve away from the tensioner arm  114 , following the movement of the piston  104 , resulting in the piston  104  being in a centered position relative to the stationary piece or hollow sleeve  100  as shown in  FIG. 1 , obtaining the position set point, moving the vibrational work piece slightly towards the tensioner arm. With the control sleeve  102  following the piston position  104 , the vibrational force of the vibrational work piece  114 , for example the tensioner arm is amplified.  
      A positioner of a second embodiment used with external means, shown here as a motor driven worm gear  218 ,  219 , is shown in  FIGS. 4 through 6 . The positioner  201  has a hollow control sleeve  202  with two open ends closed off be seals and an actuating rod  221  at either end forming a chamber. A piston  204  is slidably received within the hollow control sleeve  202  and is coupled to the actuating rod  221 , separating the chamber into a first fluid chamber  216   a , a second fluid chamber  216   b , and a third fluid chamber  216   c . The hollow control sleeve  202  contacts a vibrational work piece  214 , such that movement of the hollow control sleeve  202  moves the vibrational work piece  214 .  
      One end of the actuating rod  221  is coupled to and driven by a worm gear  218  which is driven by a motor  219  coupled to a stationary piece or the engine block  203 . The other end of the actuating rod  221  is received and irreversibly coupled to the piston  204 . The end of the actuating rod irreversibly coupled to the piston  204  has a bore  207  extending a length of the actuating rod  221 . Within the bore  207 , centered in the piston  204 , are check valves  205 ,  206  which allow fluid in one direction and block the flow of fluid in an opposite direction.  
      The first fluid chamber  216   a  is defined between an end of the piston  204 , the inner circumference  202   a  of the hollow control sleeve  202 , the seals formed as part of the control sleeve  202 , and the actuating rod  221 . The second fluid chamber  216   b  is defined between the other end of the piston  204 , the inner circumference  202   a  of the hollow control sleeve  202 , the seals  220 , and the actuating rod  221 . The third fluid chamber  216   c  is defined between the piston  204  and a groove  202   b  on the inner circumference  202   a  of the hollow control sleeve  202  extending a length. The circulation of fluid between the fluid chambers  216   a ,  216   b ,  216   c  moves the hollow control sleeve  202  and thus the vibrational work piece  214 . Passages  208 ,  209 ,  210  within the piston  204  allow fluid to pass between fluid chambers  216   a ,  216   b ,  216   c . A first piston passage  208  extends from the bore  207  to the outer circumference of the piston. A central piston passage  209  extends from the bore  207  to the third fluid chamber  216   c . A second piston passage  210  extends from the bore  207  to the outer circumference of the piston. Fluid from the first fluid chamber  216   a , when allowed, may flow through a first passage  221   a  in the actuating rod  221  to the central bore  207  and the first piston passage  208 . Fluid from the second fluid chamber  216   b , when allowed may flow through a second passage  221   b  in the actuating rod  221  to the central bore  207  and the second piston passage  210 .  
      A spring  213  is present in the first fluid chamber to bias the piston towards the worm gear. The resting spring rate of spring  213  is such that against an established set force generated by the worm gear driven by a motor, the piston is maintained in a central or null position relative to the hollow control sleeve  202  as shown in  FIG. 4 . In other words, the resting spring rate of spring  213  is substantially equal to the established set force of the motor driven worm gear.  
      In this embodiment, the piston  204  is positioned by some external means  218 ,  219 , preferably a small electric actuator, a vacuum source, or a solenoid, establishing a position set point of the vibrational work piece  214  relative to the stationary work piece  203  through the piston  204 . The external means  218 ,  219  moves the piston  204  towards the position set point. The movement of the piston  204  selectively directs fluid to flow from a first chamber  216   a  to a second chamber  216   b  or vice versa, moving the control sleeve  202  and in this case, the vibrational work piece  214  relative to the piston  204 , such that the position set point is obtained when the piston  204  is centered or at null within the control sleeve  204 .  
      In the null or central position, shown in  FIG. 4 , fluid is prevented from moving from the first fluid chamber  216   a  to the second fluid chamber or to the third fluid chamber  216   c  and vice versa. More specifically, the passages  221   a ,  221   b  in the actuating rod are open to communicate with the first fluid chamber  216   a  and the second fluid chamber  216   b , the central passage  209  is in communication with the third fluid chamber  216   c , and the first piston passage  208  and the second piston passage  210  are blocked by the inner circumference  202   a  of the hollow control sleeve  202 . Fluid is prevented is prevented from entering the central piston passage  209  through the bore  207  from the first fluid chamber  216   a  or the second fluid chamber  216   b  by the check valves  205 ,  206  in the bore  207 . The force of the spring  213  is substantially equal to the force exerted by the motor driven worm gear.  
      In  FIG. 5 , the force of the motor driven worm gear  218  on the actuating rod  221  fixed to the piston  204  is greater than the force of spring  213  on the opposite end of the piston  204 , establishing a position set point of the vibrational work piece  214  through the piston  204 . The piston  204  is moved to the left in the figure. The movement of the piston  204  causes fluid to circulate from the second fluid chamber  216   b  to the first fluid chamber  216   a , moving the control sleeve  202  in the direction of arrow  220 , resulting in the piston  204  being moved back to a centered position as shown in  FIG. 4  obtaining the position set point and moving the vibrational work piece  214  in the direction of arrow  220  to a new position. Prior to the piston  204  recentering, the first piston passage  208  is blocked by the inner circumference  202   a  of the hollow sleeve  202 , the second piston passage  210  is open to the third fluid chamber  216   c , and the central piston passage  209  is open to the third fluid chamber  216   c  and the second piston passage  210 . Fluid in the second fluid chamber  216   b , due to the movement and position of the piston  204 , flows from the second fluid chamber  216   b  through the second passage  221   b  in the actuating rod  221  through the bore  207  to the second piston passage  210 . From the second piston passage  210 , fluid moves into the third fluid chamber  216   c  and into the central piston passage  209 . From the central piston passage  209 , fluid moves into the bore  207  and through check valve  205  to the first fluid chamber  216   a  through the first passage  221   a  of the actuating rod  221 . The movement of the fluid from the second fluid chamber  216   b  to the first fluid chamber  216   a  moves the control sleeve  202 , and thus the vibrational work piece  214  in the direction of arrow  220  to a new position relative to the stationary piece  203 , following the position of the piston  204  and amplifying the small force generated by the worm gear  218  and the motor  219 . Once the control sleeve  202  and the vibrational work piece  214  have moved, the piston  204  is centered within the hollow control sleeve  202  as shown in  FIG. 4 .  
      In  FIG. 6 , the force of the motor driven worm gear  218  on the actuating rod  221  fixed to the piston  204  is less than the force of the spring  213  on the opposite end of the piston  204 , establishing a position set point of the vibrational work piece  214  through the piston  204 . The piston  204  is moved to the right in the figure. The movement of the piston  204  causes fluid to circulate from the first fluid chamber  216   a  to the second fluid chamber  216   b , moving the control sleeve  202 , resulting in the piston  204  being moved back to a centered position within the control sleeve  202  as shown in  FIG. 4 , obtaining the position set point and moving the vibrational work piece  214  in the direction of arrow  220  to a new position. Prior to the piston  204  recentering, the first piston passage  208  is open to the third fluid chamber  216   c , the second piston passage  210  is blocked by the inner circumference  202   a  of the hollow sleeve  202 , and the central piston passage  209  is open to the third fluid chamber  216   c . Fluid in the first fluid chamber  216   a , due to the movement and position of the piston  204  flows from the first fluid chamber  216   a  through the first passage  221   a  in the actuating rod  221  through the bore  207  to the first piston passage  208 . From the first piston passage  208 , fluid moves into the third fluid chamber  216   c  and into the central piston passage  209 . From the central piston passage  209 , fluid moves into the bore  207  and through check valve  206  to the second fluid chamber  216   b  through second passage  221   b  of the actuating rod  221 . The movement of the fluid from the first fluid chamber  216   a  to the second fluid chamber  216   b  moves the control sleeve  202 , and thus the vibrational work piece  214  in the direction of arrow  220  to a new position relative to the stationary work piece  203 , following the position of the piston  204  and amplifying the force generated by the worm gear  218  and the motor  219 . Once the control sleeve  202  and the vibrational work piece  214  have moved, the piston  204  is centered within the hollow control sleeve  202  as shown in  FIG. 4 .  
      While the piston was described as returning to a centered position as shown in  FIGS. 1 and 4 , other positions may also be established as the returning position.  
      The positioner of the above embodiments may also be used for variable cam timing systems or variable valve timing.  
      The vibrational work piece may be any piece in the engine that experiences vibrations.  
      Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.