Patent Publication Number: US-2015076256-A1

Title: High pressure eletrohydraulic valve actuator

Description:
BACKGROUND 
     The illustrated embodiments relate to the use of high pressure actuating fluid from a high pressure hydraulic system to drive actuators that perform valve actuation. Further, certain embodiments relate to the use of a high pressure hydraulic system that drive ancillaries on an engine, such as, for example, pressure amplified diesel injector systems, to also drive actuators that perform valve actuation. 
     An engine control unit (ECU) or other electric controllers are often used to control various aspects of the operation of an engine and/or vehicle. During engine operation, the ECU may provide instructions or data that is used to actuate actuators that are operably attached or coupled to one or more valves. The adjustment of a valve&#39;s position may be used to control a variety of different engine operations, including, for example, the rate or amount of fuel that is supplied through a fuel injector to a combustion chamber, the air-to-fuel ratio, ignition timing, and idle speed, among other operations. 
     The type of actuator(s) used to control engine and/or vehicle operations may vary. For example, the types of actuators employed for valve actuation includes electric, pneumatic/electro-pneumatic, and electro-hydraulic actuators. Electric actuators may perform valve actuation through the use of stepper motors, permanent magnet direct current (PMDC) motors, and brushless direct current (BLDC) motors. However, the reliability of electric valve actuation may be hindered by the harsh operating environments that may be present in the engine compartment or other areas of the vehicle, including elevated engine temperatures, temperature fluctuations, high vibration and exposure to potentially corrosive environmental elements. Pneumatic/electro-pneumatic valve actuation may use compressed air to control linear or rotary actuators. However, pneumatic/electro-pneumatic valve actuation may suffer from low positional accuracy due to the compressible nature of the fluids being used, such as air, and the moisture generated in an associated air compression system. 
     Electro-hydraulic valve activation uses linear and rotary actuators. Electro-hydraulic actuators typically use oil from the engine&#39;s lubricating system to operate the actuators. Therefore, during normal engine operation, the pressure of the lubricating oil that is used to operate electro-hydraulic actuators may fluctuate from approximately 30 to 100 psi. Moreover, the pressure of the lubricating oil typically varies with engine speed. Additionally, as lubricating oil is used by the engine&#39;s lubrication system, the lubricating oil supplied to operate the actuator is relatively hot. The properties of the oil change with temperature, which affects the performance of the actuator. As the pressure of the lubricating oil used to operate the actuator is relatively low, actuators typically need to be relatively large in size in order to achieve the output forces or torque needed to operate the actuator and/or the associated valve. However, increasing the size of the actuator may result in the actuator having a relatively large inertia and packaging constraints. Additionally, relatively large quantities of this low pressure lubricating oil flow needs to flow through the actuator so as to move the large actuator with force sufficient to move the actuator in a manner that allows the actuator to have the requisite power to change the position of the associated valve. Yet, the need to use relatively large quantities of lubricating oil flowing through the actuator may result in the actuator being relatively slow when moving from a rest to a start position, and when stopping the movement of the actuator. 
     BRIEF SUMMARY 
     An aspect of the illustrated embodiment is a system for operating a valve for an engine. The system includes a pump that is configured to increase the pressure of an actuating fluid to approximately 2500 to 6000 psi to provide a high pressure actuating fluid. The system also includes a supply line that is configured to deliver at least a portion of the high pressure actuating fluid to a spool valve. According to certain embodiments, the spool valve may have at least one outlet port. The system also includes at least one actuator. The actuator includes at least one chamber that is configured to receive the high pressure actuating fluid from the at least one outlet port of the spool valve. Additionally, the at least one actuator is configured to change the position of a valve when the high pressure actuating fluid is delivered to at least one of the at least one chambers. 
     Another aspect of the illustrated embodiment is a system for operating a valve for an engine. The system includes a pump that is configured to increase the pressure of an actuating fluid. A first supply line is configured to deliver at least a portion of the pressurized actuating fluid to a fuel injector. Additionally, a second supply line is configured to deliver at least a portion of the pressurized actuating fluid to a spool valve. The spool valve is configured to move from a closed position and at least one open position. At least one actuator is configured to receive the pressurized actuating fluid delivered to the spool valve when the spool valve is in an open position. The system also includes a valve that is operably attached to the at least one actuator. The valve is configured to be moved between a first position and a second position by the at least one actuator. 
     Another aspect of the illustrated embodiment is a method for operating a valve. The method includes pressurizing an actuating fluid to provide a pressurized actuating fluid. At least a portion of the pressurized actuating fluid is delivered to a fuel injector. Additionally, at least a portion of the pressurized actuating fluid is delivered to a spool valve. The spool valve may be moved to an open position. The method further includes delivering the pressurized actuating fluid through the opened spool valve to an actuator. The actuator may be operated by the flow of the pressurized actuating fluid into the actuator. Further, the operation of the actuator may move the position of a valve that is operably attached to the actuator. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  illustrates a cross-sectional view of a representative hydraulically actuated, electronically controlled fuel injector. 
         FIG. 2  illustrates a schematic of a system using a high pressure actuating fluid to operate electro-hydraulic actuators. 
         FIG. 3  illustrates a cross-sectional view of a rack and pinion actuator. 
         FIG. 4  illustrates a perspective side view of a rotary actuator. 
     
    
    
     DETAILED DESCRIPTION 
     Referencing  FIGS. 1 and 2 , fuel injectors  100  may be used with a hydraulically actuated, electronically controlled, unit fuel injection system (HEUI). In an HEUI fuel system, an actuating fluid, such as oil, is supplied at high pressure through a hose, tube, or common rail  204  to each of a series of unit fuel injectors  100  within the cylinder head. Prior to delivery, the pressure of the actuating fluid may be increased by a high-pressure fluid pump and/or a hydraulic amplification system  202 . This high-pressure fluid pump may be driven by a variety of sources, such as, for example being an engine power-take off component or driven electrically. According to certain embodiments, the hydraulic amplification system  202  may be used to elevate the pressure of the actuating fluid to approximately 2500 to 6000 psi. However, the pressures obtained by the amplification system may be dependent on the type and/or size of the pump used by the amplification system  202 . Fluid from the rail  202  may be delivered to the fuel injector  100  through a fluid inlet  101  in the fuel injector  100 . 
     Referencing  FIG. 1 , each injector  100  includes an electronically controlled control valve  108  that governs the application of the high pressure actuating fluid to provide a force used by the injector  100  to inject fuel into the engine cylinder. Moreover, the control valve  108  may be used to control the timing and amount of the actuating fluid flowing into the injector  100  through a fluid inlet  101 . 
     The actuating fluid control valve  108  may at least assist in initiating, and the termination of, the fuel injection process. For example, the control valve  108  may be a spool valve that is controlled by the ECU  212 . According to certain embodiments, the ECU  212  may control the application of an electric current being delivered across one or more coils  115  that causes a cylinder  109  of the spool valve to move, such as, for example, slide, between first and second positions. By moving the cylinder  109  to the second position, an actuating fluid pathway that was previously closed or blocked by the cylinder  109  may be opened. Actuating fluid may then be able to flow through the pathway to a location adjacent to a top portion of a plunger  102 . The plunger  102  may be positioned within an internal pumping chamber  104  of an intensifier piston  106  of the fuel injector  100 . Accumulated actuating fluid may provide a force that downwardly displaces the plunger  102 , which amplifies the fuel pressure in the pumping chamber  104  to a magnitude large enough to force a normally closed valve  110 , such as a needle valve, at an outlet  112  of the fuel injector  100  to open. When the latter valve  110  opens, the amplified fuel pressure forces fuel through the outlet  112  and into the combustion chamber of the engine. 
     The injection of fuel from the fuel injector  100  may be terminated by terminating a control signal to the electronically control valve  108 . When that happens, the valve  110  at the outlet  112  of the fuel injector  100  may return to a normally closed condition, and fuel flows from the rail to refill the pumping chamber, forcing the plunger  102  to retract in the process. The actuating fluid in the fuel injector  100  that was used to displace the plunger  102  may then be exhausted from the fuel injector  100 , and at least a portion of the actuating fluid may eventually be collected in a sump  208 , as shown in  FIG. 2 . Further, the cylinder  109  Of the spool valve may return to a first position in which the cylinder  109  closes or blocks the actuating fluid pathway. 
     Besides being used in the operation of a fuel injector  100 , the high pressure actuating fluid may be used in operating one or more actuators  206 . For example, for illustration purposes,  FIG. 2  provides a schematic of a system  200  using high pressure actuating fluid to operate one or more electro-hydraulic actuators  206 . Such a system  200  may replace the use of low pressure lubricating oil with the relatively substantially higher pressurized actuating fluid. While  FIG. 2  illustrates the use of the hydraulic amplification system  202  that is also used for fuel injectors  100 , according to other embodiments, the system  200  may have a dedicated pump that is used to drive the actuators  206 , and is not used for pressurizing fuel for the fuel injectors  100 . Such an embodiment may be particularly suited for engines such as diesel engines that use common rail direct injection systems, were the diesel injection pressure is not amplified by hydraulic system but is pressurized by a high pressure diesel fuel pump. 
     As shown, the system  200  includes the high pressure pump or hydraulic amplification system  202  that is used to increase the pressure of the actuating fluid. At least a portion of the actuating fluid may be delivered to one or more fuel injectors  100  through the common rail  204 , as previously discussed. At least a portion of the high pressure actuator fluid is also supplied to a spool valve  208  that is used operate an actuator  206  in a manner similar to the spool valve used to operate the injector  100 . According to certain embodiments, the spool valve  208  may be a traditional hydraulic spool valve  208  that has one or more ports to direct the high pressure actuating fluid into and out of the spool valve  208 , as discussed below in more detail. 
     For illustrative purposes, the spool valve  208  shown in  FIG. 2  is a three-way port valve, in which the spool valve  208  has an inlet port  203 , an outlet port  205 , and a discharge port  207 . The inlet port  203  of the spool valve  208  receives high pressure actuation fluid from the hydraulic amplification system  202  through a supply line or hose  210 . When the actuator  206  is to be activated, the high pressure actuating fluid may exit the spool valve  208  through the outlet port  205  of the spool valve  208 , wherein the high pressure actuating fluid is delivered to a chamber of the actuator  206 , such as a first chamber, through an actuating fluid supply line  214 . When the outlet port  205  is closed, the discharge port  207  of the spool valve  208  may be opened, thereby allowing high pressure actuating fluid delivered to the spool valve  208  to be delivered to a sump  208  via a return line  215 . When the outlet port  205  is closed and high pressure actuating fluid is not being supplied to the actuator  206 , the actuator may return to a first position by a spring. However, according to other embodiments in which the spool valve  208  has more than one outlet port  205 , such as when the actuator is a four-way valve, a second outlet port may be used to deliver high pressure actuating fluid to a second chamber of the actuator  206  while high pressure actuating fluid is evacuated from the first chamber of the actuator  206 . In such embodiments, the delivery of high pressure actuating fluid to the second chamber may cause the actuator  206  to move in a direction opposite to that of when the high pressure actuating fluid was delivered to the first chamber of the actuator  206 . 
     Actuating fluid may be delivered through one or more inlet tubes or hoses  210  to an inlet port  203  of the spool valve  208 . The operation of the spool valve  208  may be controlled by the ECU  212 , which may employ electronic hardware used to operate the spool valve  208  that are the same or similar to the electronic hardware used to operate the control valve  108  of the fuel injector  100 . The ECU  212  may deliver a signal or electric current that is used to move a cylinder within the spool valve  208  between a closed position and one or more open positions or positions therebetween. Similar to the control valve of the injector  108 , the cylinder of the spool valve  208  may be moved through the application of electrical current that draws or repels the cylinder of the spool valve  208  to/away from different valve positions. 
     The position of the spool valve  208  may influence which direction the actuator  206  moves the attached valve  216 , and thereby change the position of the valve  216 , including for example, moving the valve  216  between open and closed positions, a vice versa, as well as positions there between. For example, each of the open positions of the spool valve  208  may be in communication with a different inlet ports and chambers in the actuator  206 . According to certain embodiments, if the spool valve  208  is in a first open position, actuating fluid may flow through a first outlet port  205  in the spool valve  208 , through an actuator supply line  214 , and enter an inlet of a first chamber of a rotary actuator. The high pressure actuating fluid may then flow through the first chamber from the first chamber inlet to the first chamber outlet. This flow path may cause a shaft of the rotary actuator  206  that drives a valve  216  to move in either a clockwise or counterclockwise direction. Conversely, in this example, if the spool valve  208  has second outlet port, when the first outlet port  205  of the spool valve  208  is closed and the second outlet port is open, actuating fluid may flow out of the second outlet and be delivered to the inlet of a second chamber of the actuator  206 . The actuating fluid may then flow in a direction in the second chamber that causes the shaft of the actuator  206  to move in a direction opposite of that which the shaft was moving when the high pressure actuating fluid was being supplied to the first chamber. Further, while actuating fluid is being supplied to the second chamber of the actuator  206 , actuating fluid may be being exhausted from the first chamber of the actuator  206 . 
     Unlike electro-hydraulic linear or rotary actuators typically used in vehicles, the actuators  206  in the illustrated embodiment are driven by high pressure actuating fluid, such as, for example, actuating fluid that has a pressure of around 4000 psi. By delivering such high pressure actuating fluid to the actuator  206 , the electro-hydraulic actuators  206  may have miniaturized components in comparison to similar actuators that operate by the lower pressure engine lubricating oil. For example, if the valve  216  that is being operated by a rack and pinion actuator requires that actuator  206  achieve a continuous torque of 5 N-m, the use of lubricating oil at a typical pressure of 100 psi would require the use of a 25 mm pinion traveling 25 mm, which would require a volumetric displacement of lubricating oil of approximately 12,272 mm 3  through the actuator. However, if the same 5 N-m torque were provided by a rack and pinion actuator  206  driven by the high pressure actuating fluid described as herein, a 4000 psi actuating fluid could obtain the same 5 N-m through using a 9 mm diameter piston traveling only 5 mm, which would use a volumetric displacement actuating fluid of approximately 318 mm 3  through the actuator  206 . Thus, the use of the high pressure actuating fluid may allow the size of the rack and pinion electrohydraulic actuator  206  to be significantly reduced. Additionally, the use of a substantially smaller amount of fluid to drive the actuator  206  (in the prior example approximately 318 mm 3  versus approximately 12,272 mm 3 ) also allows for faster response times when an actuator  206  is to start moving after being in a rest condition and when movement of the actuator  206  is to stop. Additionally, a balance may be arrived between the size of the pump  202  needed for the actuating fluid to have the high pressure, and the fact that the pump  202  needs to displace a substantially smaller quantity of actuating fluid to operate the actuators  206 . 
     Further, by being able to reduce the size of the actuator  206  in the present system, the electro-hydraulic actuator  206  may also be positioned at locations that are not typically permissible for actuators that are operated with low pressure lubricating oil. For example, the miniature sizes for the rack and pinion electro-hydraulic actuator  206  that may be obtained by the present system  200  may be designed as an integral part of the housing for the valve  216  that is being operated by the actuator  206 , including, for example, being contained in the valve  216 . Thus, while the spool valve  208  illustrated in  FIG. 2  is shown as being separate from the actuator  206 , according to other embodiments, the spool valve  208  may be attached to or part of the actuator  206 . 
     A variety of different types of hydro-electric actuators  206  may be used by the present system  200 , such as linear and rotary actuators. For example, for illustrative purposes,  FIG. 3  demonstrates a cross-sectional view of a rack and pinion actuator  300  that may be used with the illustrated system  200 . As shown, the rack and pinion actuator  300  includes a pinion  302 , a rack  304 , and a casing  308 . High pressure actuating fluid may enter into the casing  308  through a first inlet port  305  and flow along a chamber  307  of the casing  308  before flowing out of the casing  308  through a first outlet port  309 . The chamber  307  is typically separate from the rack  304  and the pinion  302  so that high pressure actuating fluid does not flow in contact from the rack  304  and the pinion  302  as the actuating fluid flows through the chamber  307 . The flow of the high pressure actuating fluid may be used to move or push the rack  304 . As the rack  304  moves, teeth  311  in the rack  304  may engage serrations or teeth  313  in the pinion  302 , and thereby cause the pinion  302  to rotate in a clockwise direction. The rotation of the pinion  302  may drive a shaft  312  that is connected or coupled to the pinion  302  and the valve  216  and that transmits the torque to at least assist in changing the position of the valve  216 . 
     In addition, or in lieu of utilizing multiple spool valve  208  outlet ports  205 , the rack and pinion actuator  300  and the spool valve  208  may be further minimized in size and/or complexity through the use of a spring return approach. According to such an embodiment, the rack and pinion actuator  300  may include a first inlet port  305  and a first outlet port  309  that use the hydraulic pressure from the actuating fluid flowing through the first inlet port  305  to drive the shaft  312  in one direction. When actuating fluid is no longer supplied to the chamber, a compression spring may be used to drive the shaft  312  of the rack and pinion actuator  300  in the opposite direction. According to such certain embodiments, at times during operation, the actuating fluid may be supplied to the rack and pinion actuator  300  at a rate sufficient to prevent movement of the shaft  312  by either the hydraulic pressure of the actuating fluid or pressure from the compression spring. 
     Given the relatively small sizes attainable for the pinion  302  and rack  304  for the actuator  300  in the illustrate system  200 , the shaft  312  may also be used as a position sensor component. The sensor component may be used to provide the ECU  212  with data or information indicating, or to be used to determine, the position of the actuator  206 ,  300  and/or the valve  216 . For example, according to certain embodiments, the pinion  302  may include, or have attached thereto, an annular permanent magnet  306 , while the housing or casing  308  of the actuator  206  includes a coil  310 . According to such an embodiment, the movement of the magnet may be detected by one or more magneto resistive Hall Effect sensors. However, the actuator  206  and/or valve  216  may include a variety of other, different ways to sense the position of the actuator  206 ,  300  and/or the valve  216 . For example, the position of the valve  216  can be sensed using non-contact rotational sensor that senses the movement of the pinion  302  or the shaft  312  that is attached or coupled to the pinion  302 . 
       FIG. 4  illustrates a perspective side view of a typical rotary actuator  400  having a housing  402 , a shaft  404 , at least one vane  406 , a first port  408 , and a second port  410 . As with such rotary actuators  400 , the supply of high pressure actuating fluid through the first and second ports  408 ,  410  to the housing  402  causes the vane  406  and attached shaft  404  to move in a circular direction about the housing  402 . The direction of the movement of the shaft  404  may be determined by which inlet port  408  is supplied with actuating fluid from the spool valve  208 . Accordingly, the rotary actuator  400  may be configured to move the vane  406 , and thus the shaft  404 , in a clockwise direction when the high pressure actuating fluid is supplied to housing through the first or second port  408 ,  410  and in a counter-clockwise direction when the actuating fluid is supplied to the other of the first or second port  408 ,  410 . Further, as the high pressure actuating fluid is being supplied from the spool valve  208  to one of the first and second ports  408 ,  410 , a separate exhaust port may be used to evacuate high pressure fluid that was already in housing  402  so that pressure from the incoming high pressure actuating fluid may move the vane  406 . 
     The rotary actuator valve  400  and associated spool valve  208  may be simplified by the addition of a torsional spring. More specifically, according to certain embodiments, the spool valve  208  may be simplified so that high pressure actuating fluid is delivered to one port  408 . High pressure actuating fluid may enter into the housing  402  to move the shaft  404  in a first direction. When the shaft  404  is to be moved in the second, opposite direction, the high pressure actuating fluid that entered into the housing  402  through the port  408  may at least be partially evacuated from the housing  402 , such as through a separate exhaust port in the actuator  400 , thereby allowing the force associated with the torsional spring to move the shaft in the second direction. 
     Referring back to  FIG. 2 , as high pressure actuating fluid exits the actuator  206 , such as, for example, through the outlet port  309 , the high pressure actuating fluid may be delivered to the sump  208  through an outlet tube  209 . Actuating fluid that accumulates in the sump  208  may then be delivered to the pump or hydraulic pressure amplification system  202  by a return hose or tube  218  to be recirculated in the system  200  for use again by the fuel injectors  100  or the actuators  206  as a high pressure actuating fluid.