Abstract:
An internal combustion engine that has a camshaft having a plurality of cam lobes, a plurality of valves where each of the valves are actuated by a lifter actuated by the camshaft with a cam lobe. The lifter comprises a lifter body having an upper surface and a lower surface. A cam contact plate pivots on an axis on the upper surface of the lifter body. Opposed hydraulic actuators are present on either side of the axis of the cam contact plate, where each hydraulic actuators comprise a fluid chamber in the lifter body, a piston in the chamber, and a spring biasing the piston into contact with the cam contact plate. The lifter further comprises a line supplying hydraulic fluid to the fluid chambers of the hydraulic actuators and a control valve for controlling fluid flow from one hydraulic actuator to the other hydraulic actuator.

Description:
REFERENCE TO RELATED APPLICATIONS 
   This application claims an invention which was disclosed in Provisional Application No. 60/515,096, filed Oct. 27, 2003, entitled “PIVOTING LIFTER CONTROL SYSTEM USING CONTROL VALVE TO RECIRCULATE FLUID.” The benefit under 35 USC §119(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 pivoting lifters. More particularly, the invention pertains to a control system for pivoting lifters using valves to recirculate oil. 
   2. Description of Related Art 
   Conventionally, variable lift systems require oil pressure from the engine to disengage a pin on the lifter. This added oil requirement means that the oil pump must be upsized for the short periods of time that the lifter is switched. The upsized pump adds to the parasitic loss of the engine and can increase fuel consumption. 
   Prior art U.S. Pat. No. 6,357,406, hereby incorporated by reference, teaches a method of controlling the oil into and out of two solenoid valves controlling the two sides of the lifter plate. 
   U.S. Pat. No. 6,257,183 discloses a lost motion valve actuation system where a trigger valve acts as an on/off valve in directing fluid to an accumulator. The accumulator is directly hydraulically connected to the on/off valve as well as passages leading to and from the exhaust and intake tappets. Check valves are placed in the passages between the trigger valves and the tappets, permitting flow from the tappets to the trigger valve. The accumulator comprises a spring biasing means for urging a piston in a direction to decrease the size of the chamber in the accumulator. The accumulator provides surge volume and source of makeup oil and pressure to the lost motion valve actuation system. The lost motion valve actuation system does not allow proportional control of the flow of fluid and fluid is not recirculated through the on/off valve but comes directly out of the accumulator.  FIG. 1  shows a graph of valve lift versus crank angle. As shown in the graph the lost motion valve actuation system changes the cam lift profile. 
   JP61093216A discloses a check valve that feeds oil into the pressure chambers of a tappet, which is forcibly closed by a solenoid valve. The solenoid valve is controlled by a controller in accordance with engine conditions. 
   JP62126213A provides oil from a remote location to communicate with an oil chamber adjacent to the tappet holder through a check valve. 
   JP62203911 discloses a solenoid valve that supplies working fluid to a chamber via a check valve during high loaded engine operations. The working fluid form the chamber lifts a control rod against a spring force to set valve timing. 
   SUMMARY OF THE INVENTION 
   An internal combustion engine that has a camshaft having a plurality of cam lobes, a plurality of valves where each of the valves are actuated by a lifter actuated by the camshaft with a cam lobe. The lifter comprises a lifter body having an upper surface and a lower surface. A cam contact plate pivots on an axis on the upper surface of the lifter body. Opposed hydraulic actuators are present on either side of the axis of the cam contact plate, where each hydraulic actuators comprise a fluid chamber in the lifter body, a piston in the chamber, and a spring biasing the piston into contact with the cam contact plate. The lifter further comprises a line supplying hydraulic fluid to the fluid chambers of the hydraulic actuators and a control valve for controlling fluid flow from one hydraulic actuator to the other hydraulic actuator. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  shows a graph of valve lift versus crank angle of prior art U.S. Pat. No. 6,257,183. 
       FIG. 2  shows a graph of valve lift versus crank angle of the present invention. 
       FIG. 3  shows a schematic of the pivoting lifter of the present invention. 
       FIG. 4  shows a schematic of the pivoting lifter control system in the first position. 
       FIG. 5  shows a schematic of the pivoting lifter control system maintaining the first position. 
       FIG. 6  shows a schematic of the pivoting lifter control system when the spool is moved to a second position. 
       FIG. 7  shows a schematic of the pivoting lifter control system maintaining the second position of the spool. 
       FIG. 8  shows a schematic of the pivoting lifter system when make-up oil is supplied. 
       FIG. 9  shows a schematic of an alternate embodiment of the pivoting lifter system in the first position. 
       FIG. 10  shows a schematic of an alternate embodiment of the pivoting lifter system maintaining the first position. 
       FIG. 11  shows a schematic of an alternate embodiment of the pivoting lifter system in the second position. 
       FIG. 12  shows a schematic of an alternate embodiment of the pivoting lifter system in maintaining the second position. 
       FIG. 13  shows a schematic of an alternate embodiment in which the make-up oil is supplied. 
       FIG. 14  a schematic of another embodiment of the pivoting lifter system in the first position. 
       FIG. 15  shows a schematic of another embodiment of the pivoting lifter system maintaining the first position. 
       FIG. 16  shows a schematic of another embodiment of the pivoting lifter system in the second position. 
       FIG. 17  shows a schematic of another embodiment of the pivoting lifter system in maintaining the second position. 
       FIG. 18  shows a schematic of another embodiment in which the make-up oil is supplied. 
       FIG. 19  shows a schematic of an alternative control valve. 
       FIG. 20  shows a schematic of another alternative control valve. 
       FIG. 21  shows a schematic of the control valve shown in  FIGS. 14 through 18 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Valve actuation systems or pivoting lifter systems are used in an engine to vary the timing and lift of the intake and exhaust valves of the engine. The present invention uses a system that recirculates hydraulic fluid from one hydraulic actuator to another using the force of the camshaft lobe as it rotates around.  FIG. 2  shows a graph of valve lift versus crank angle. As opposed to the prior art, the pivoting lifter system of the present invention does not change the cam lift profile, instead the phase is shifted such that a first cam lift profile overlaps with the next cam lift profile. 
     FIG. 3  shows an overall schematic of the pivoting lifter in the engine. A valve stem  166  connects valve head  164  to lifter body  158 . Spring  160  biases the valve head  164  to come into contact with valve seat  162  of the engine block. Chambers in the lifter body  158  receive hydraulic actuators  105 ,  106 . Hydraulic actuators  105 ,  106  may be hollow or solid pistons biased by a spring (not shown). The pivoting lifter plate or cam contact plate  116  is in contact with both the hydraulic actuators  105 ,  106  and cam lobe  120 . The position of the both the hydraulic actuators  105 ,  106  in the chambers of the lifter body  158  is influenced by the position of the cam lobe as it contacts the pivoting lifter plate or cam contact plate  116 . 
     FIGS. 4 through 7  show the positions of the cam lobe as it rotates and contacts the pivoting lifter plate  116 .  FIG. 4  shows the cam lobe  120  contacting and pressing down on the pivoting lifter plate  116 .  FIG. 5  shows the position of the cam lobe  120  after it has rotated counterclockwise and maintenance of the position of the pivoting lifter plate.  FIG. 6  shows the cam lobe  120  just prior to lobe rotating counterclockwise again, after the spool position has changed.  FIG. 7  shows the cam lobe  120  just after the lobe has rotated counterclockwise and maintenance of the position of the pivoting lifter plate. 
     FIG. 4  shows a schematic of the pivoting lifter of a first embodiment. Hydraulic fluid or oil is supplied from a source to an inlet line  110 , which passes through check valve  122  to control valve  109 . The control valve  109  is slidable back and forth and has two lands  109   a  and  109   b  each of which fit snuggly within a bore in the head. The control valve  109  is biased by a spring  118  on one side and a variable force actuator  103 , which may be a variable force solenoid on the other. The variable force actuator  103  is controlled by the engine control unit (ECU)  102 . The position of the control valve  109 , inwards or outwards, determines the flow of oil, to and from each of the hydraulic actuators  105 ,  106  adjacent to the pivoting lifter plate or cam contacting plate  116  in addition to the force exerted on the lifter plate  116  by the cam lobe  120 . In this embodiment, the hydraulic actuators  105 ,  106  comprise a hollow piston  152 , a fluid chamber  156 , and a spring  154 , though as mentioned previously may comprise a solid piston and a spring. 
   As shown in  FIG. 4 , the control valve  109  is in an outward position and hydraulic fluid flows into inlet line  110  through check valve  122  and through control valve  109  to line  111 . Line  111  branches into two paths, leading to lines  112 ,  113 , each containing a check valve  114 ,  115  respectively. The check valves  114 ,  115  allow fluid into lines  112 ,  113  only. Each of the paths  112 ,  113  leads to a hydraulic actuator  105 ,  106  respectively. Hydraulic fluid enters the fluid chamber  156  of the hydraulic actuator  105  overcoming the force of spring  154  to move the hollow piston  152  up, raising the pivoting lifter plate on the right side, as shown in the Figure. At the same time, the force of the cam lobe  120  pressing down on the pivoting lifter plate  116 , compressing spring  154  which causes hydraulic fluid in the hydraulic actuator  106  to exhaust to line  113 . Hydraulic fluid from line  113  feeds through control valve  109  into line  111  until mostly all the fluid is exhausted from hydraulic actuator  106 . From line  111 , fluid enters line  112  and fluid chamber  156  of hydraulic actuator  105  through check valve  114 . Once most of the fluid has exhausted from hydraulic actuator  106  and cam lobe  120  begins to rotate, most of the hydraulic fluid has passed through line  111  and check valve  114  closes due to lack of pressure and fluid. Since land  109   b  blocks line  112  from recirculating fluid through the control valve  109  and check valve  114  blocks recirculation of fluid, fluid in the hydraulic actuator  105  remains in place as shown in  FIG. 5 , until control valve  109  moves again to a retard position. 
   The control valve  109  is moved inward by the variable force actuator  103  as the cam lobe  120  presses down on the pivoting lifter plate  116 . The control valve  109  movement to the retard position and the cam lobe  120  pressure on the pivoting lifter plate  116  and the hydraulic actuator  105 , causes the spring  154  to compress and fluid to exhaust from the fluid chamber  156  into line  112 . From line  112  fluid enters the control valve  109  and line  111 . The fluid and pressure causes check valve  115  to open, allowing fluid into line  113  which leads to hydraulic actuator  106 . As the fluid fills chamber  156 , spring  154  expands, pushing up on hollow piston  152  and pivoting lifter plate  116 , raising the left side of the plate  116 . Additional fluid is added to line  111  from inlet line  110  for makeup purposes. 
   Once most of the fluid has exhausted from hydraulic actuator  105  and cam lobe  120  begins to rotate, most of the hydraulic fluid has passed through line  111  and check valve  115  closes due to lack of pressure and fluid. Since land  109   a  blocks line  113  from recirculating fluid through the control valve  109  and check valve  115  blocks recirculation of fluid, fluid in the hydraulic actuator  106  remains in place as shown in  FIG. 7 , until control valve  109  moves again. 
   Makeup fluid is provided as shown in  FIG. 8 , when the control valve  109  is a null position. Hydraulic fluid from inlet line  110  flows through check valve  122  and control valve  109  into line  111 . From line  111 , fluid flows through check valves  114 ,  115  to lines  112 ,  113  and into hydraulic actuators  105 ,  106  respectively. 
     FIGS. 9 through 12  show the positions of the cam lobe  220  as it rotates and contacts the pivoting lifter plate or cam contacting plate  216  in a second embodiment.  FIG. 9  shows the cam lobe  220  contacting and pressing down on the pivoting lifter plate  216 .  FIG. 10  shows the position of the cam lobe  220  after it has rotated counterclockwise and maintenance of the position of the pivoting lifter plate.  FIG. 11  shows the cam lobe  220  just prior to the lobe rotating counterclockwise again after the spool position has changed.  FIG. 12  shows the cam lobe  220  just after the lobe has rotated counterclockwise and maintenance of the position of the pivoting lifter plate. 
     FIG. 9  shows a schematic of the pivoting lifter of a second embodiment. Hydraulic fluid is supplied from a source to an inlet line  210  which passes through either check valve  228  or  230  to provide the hydraulic fluid when the system is initially started (not shown) or when additional fluid is needed by the system for makeup purposes. Check valves  228 ,  230  only allow fluid into lines  212 ,  213  respectively. Assuming that fluid is already present in the system, a control valve  209 , is slidable back and forth and has three lands,  209   a ,  209   b ,  209   c , each of which fit snuggly within a bore in the head. The control valve  209  is biased by a spring  218  on one side and variable force actuator  203 , which may me a variable force solenoid, on the other. The variable force actuator  203  is controlled by the ECU  202 . The position of the control valve  209 , inwards or outwards determines the flow of oil to and from each of the hydraulic actuators  205 ,  206  adjacent to the pivoting lifter plate or cam contacting plate  216  in addition to the force exerted on the lifter  216 . The hydraulic actuators  205 ,  206  comprise a hollow piston  252 , a fluid chamber  256 , and a spring  254 , though the hydraulic actuators may also comprise a solid piston and a spring. 
   As shown in  FIG. 9 , the control valve is in an outward position. The cam lobe  220  is pressing down on the pivoting lifter plate  216 , compressing spring  254 , which causes hydraulic fluid in the hydraulic actuator  206  to exhaust to line  113 . Hydraulic fluid from line  113  feeds through control valve  209  and into line  211  until mostly all the fluid is exhausted from hydraulic actuator  206 . From line  211 , fluid enters line  212  and fluid chamber  256  of hydraulic actuator  206  through check valve  214 , overcoming the force of the spring  254  to raise the hollow piston on the right side, as shown in the Figure, and thus raising the right side of the pivoting lifter plate  216 . Once most of the fluid has exhausted from hydraulic actuator  206  and cam lobe  220  begins to rotate, most of the hydraulic fluid has passed through line  211  and check valve  214  closes due to lack of pressure and fluid. Since land  209   b  blocks line  212  from recirculating fluid through the control valve  209  and check valves  214 ,  228 , fluid in hydraulic actuator  205  remains in place as shown in  FIG. 10 , until control valve  209  moves again to a retard position. 
   The control valve  209  is moved inward by the variable force actuator  203 , compressing spring  218  as the cam lobe  220  presses down on the pivoting lifter plate  216 . The control valve  209  movement to the retard position and the cam lobe  220  pressure on the pivoting lifter plate  216  and the hydraulic actuator  205 , causes the spring  254  to compress and fluid to exhaust from the fluid chamber  256  into line  212 . From line  212  fluid enters the control valve  209  and line  211 . The fluid and pressure causes check valve  215  to open, allowing fluid into line  213  which leads to hydraulic actuator  206 . As the fluid fills chamber  256 , spring  254  expands, pushing up on hollow piston  252  and pivoting lifter plate  216 , raising the left side of the plate  216 . 
   Once most of the fluid has exhausted from hydraulic actuator  205  and cam lobe  220  begins to rotate, most of the hydraulic fluid has passed through line  211  and check valve  215  closes due to lack of pressure and fluid. Since land  209   a  blocks line  213  from recirculating fluid through the control valve  209  and check valves  215 ,  230  blocks recirculation of fluid, fluid in the hydraulic actuator  206  remains in place as shown in  FIG. 12 , until control valve  209  moves again. 
   Makeup fluid is provided in the null position of the control valve  209 , as shown in  FIG. 13 . Hydraulic fluid from inlet line  210  flows through check valves  228 ,  230  and into lines  212 ,  213 . From lines  212 ,  213  fluid flows into hydraulic actuators  205 ,  206  respectively. 
     FIGS. 14 through 17  show the positions of the cam lobe as it rotates and contacts the pivoting lifter plate in a third embodiment.  FIG. 14  shows the cam lobe  320  contacting and pressing down on the pivoting lifter plate  316 .  FIG. 15  shows the position of the cam lobe  320  after it has rotated counterclockwise and maintenance of the position of the pivoting lifter plate.  FIG. 16  shows the cam lobe  320  just prior to the lobe rotating counterclockwise again after the spool position has changed.  FIG. 17  shows the cam lobe  320  just after the lobe has rotated counterclockwise and maintenance of the pivoting lifter plate.  FIG. 18  shows the cam lobe in the middle of rotation, when it is not applying any pressure on the pivoting lifter plate.  FIG. 21  shows a schematic of the control valve in the third embodiment. 
     FIG. 14  shows a schematic of the pivoting lifter of a third embodiment. Hydraulic fluid is supplied from a source to inlet lines  342 ,  344 , where the fluid passes through check valves  346 ,  348  respectively to provide hydraulic fluid when the system is initially started (not shown) or when additional fluid is needed by the system for makeup purposes. Check valves  346 ,  348  only allow fluid into lines  312 ,  313  respectively. Assuming that fluid is already present in the system, a control valve  309 , is slidable back and forth and has three lands,  309   a ,  309   b ,  309   c , each of which fit snuggly within the a bore in the head of the engine. The control valve  309  is biased by a spring  318  on one side and a variable force actuator  303  on the other, in this case a variable force solenoid. The variable force actuator  303  is controlled by the ECU  302 . The position of the control valve  309 , inwards or outwards determines the flow of oil to and from each of the hydraulic actuators  305 ,  306  adjacent to the pivoting lifter plate  316  in addition to the force exerted on the lifter  316 . The hydraulic actuators  305 ,  306  comprise a hollow piston  352 , a fluid chamber  356 , and a spring  354 . 
   As shown in  FIG. 14 , the control valve  309  is in an inward position. The cam lobe  320  is pressing down on the pivoting lifter plate  316 , compressing spring  354 , which causes hydraulic fluid in the hydraulic actuator  306  to exhaust to line  313 . Hydraulic fluid from line  313  feeds through control valve  309  and into line  340 . Since control valve land  309   c  blocks entry back into the control valve from line  340 , fluid enters line  350  through check valve  322  and into the control valve  309  to line  312  between lands  309   b  and  309   c . Fluid in line  312  enters fluid chamber  356  of hydraulic actuator  305 , overcoming the force of spring  354  to raise the hollow piston  352  on the right side, as shown in  FIG. 14 , and thus raising the right side of the pivoting lifter plate  316 . 
     FIG. 15  shows the position of the cam lobe  320  after it has rotated counterclockwise. Fluid from the hydraulic actuator  305  exhausts into line  312  to the control valve  309 . From the control valve  309 , the fluid enters line  350  and is blocked by check valve  322 . Fluid is also blocked from entering line  342  by check valve  346 . Since the fluid is prevented from exiting the hydraulic actuator  305  and line  312  to line  340 , the position of the pivoting lifter plate  316  is maintained. 
     FIG. 16  shows the spool in the outward position. In this position, the cam love  20  presses down on the pivoting lifter plate  316 , compressing spring  354 , which causes  5  hydraulic fluid in the hydraulic actuator  305  to exhaust to line  312 . Hydraulic fluid from line  312  feeds through control valve  309  and into line  340 . Since control valve land  309   b  blocks entry back into the control valve from line  340 , fluid enters line  350  through check valve  322  and into control valve  309  to line  313  between lands  309   b  and  309   c . Fluid in line  313  enters fluid chamber  356  of hydraulic actuator  306 , overcoming the force of spring  354  to raise the hollow piston  352  on the left side, as shown in  FIG. 16 , and thus raising the left side of the pivoting lifter plate  316 . 
     FIG. 17  shows the position of the cam lobe  320  after it has rotated counterclockwise again. Fluid from the hydraulic actuator  306  exhausts into line  313  to the control valve  309 . From the control valve  309 , the fluid enters line  350  and is blocked by check valve  322 . Fluid is also blocked from entering line  344  by check valve  348 . Since the fluid is prevented from exiting the hydraulic actuator  306  and line  313  to line  340 , the position of the pivoting lifter plate  316  is maintained. 
   Makeup fluid is supplied to the system as shown in  FIG. 18 . Makeup fluid enters through lines  342 ,  344  through check valves  346 ,  348  respectively from an oil supply (not shown) when the cam lobe  320  is in the middle of rotation and the cam lobe is not applying any pressure on the pivoting lifter plate  316 . 
     FIGS. 19 through 21  shows alternative control valves that may be used in the pivoting lifter system. A supply line (not shown) is necessary to supply makeup fluid for each of the systems show in the figures.  FIG. 19  shows control valve  409 , in this case a rotatable one way valve containing a check valve. Lines  412 ,  413  are connected to chambers in the lifter body  458  containing hydraulic actuators  405 ,  406  and enter either side of control valve  409 . Depending on how the control valve  409  is rotated, fluid may only go from one hydraulic actuator to another or remain in the hydraulic actuator  405 ,  406 . Cam contacting plate or pivoting lifter plate  416  rotates about an axis depending on the positions of the hydraulic actuators  405 ,  406  and cam lobe  420 . 
     FIG. 20  shows another alternate control valve. In this case, the control valve comprises two separate solenoids  508 ,  509 . Each solenoid may be turned on or off and has a line  513  which enters the solenoids  508 ,  509  on one side and a line  512  leaving the solenoids  509 ,  508  with check valves  514 ,  515  on the other side. Lines  512 ,  513  are also connected to the chambers in the lifter body  558  containing the hydraulic actuators  505 .  506 . Fluid from line  512  may enter control valve  508  though check valve  515  and to line  513  which leads to hydraulic actuator  506 . Fluid from line  513  may enter control valve  509  through check valve  514  to enter line  512  and hydraulic actuator  505 . Cam contacting plate or pivoting lifter plate  516  rotates about an axis depending on the positions of the hydraulic actuators  505 ,  506  and cam lobe  520 . 
     FIG. 21  shows the control valve present in the third embodiment shown in  FIGS. 14 through 18 . Lines  613  and  612  lead from hydraulic actuators  606 ,  605  respectively, to control valve  609 . Off of lines  612 ,  613  are check valves  614 ,  615  for providing makeup fluid to the system. Control valve  609  is comprised of three ports, port  609   a ,  609   b , and  609   c . Port  609   a  allows fluid to move from hydraulic actuator  606  through line  613 , through control valve  609  and check valve  622  and back through the control valve  609  to line  612  and hydraulic actuator  605 . Port  609   b  maintains the positions of the hydraulic actuators  605 ,  606  and the pivoting lifter plate  616 . Port  609   c  allows fluid to move from hydraulic actuator  605  through line  612 , through control valve  609  and check valve  622  and back through the control valve to line  613  and hydraulic actuator  613 . 
   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.