Patent Abstract:
A pump system including a control system for controlling a variable flow pump for controlling oil flow and oil pressure in a hydraulic circuit in an engine. The system includes a pump member, an actuating member capable of controlling the flow generated by the pump member, and a solenoid valve system including a solenoid valve portion and a pressure regulator valve portion. The solenoid valve system is operably associated with the pump and the pressure regulator valve portion is operably associated with the actuating member for selectively controlling the flow generated by the pump member. An electronic control unit is operably associated with the solenoid valve portion, wherein the electronic control unit is selectively operable to provide an input control signal to the solenoid valve portion for controlling oil flow and oil pressure.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The instant application is a continuation-in-part of U.S. patent application Ser. No. 10/406,575, filed Apr. 3, 2003, which claims priority to U.S. Provisional Patent Application Ser. No. 60/369,829, filed Apr. 3, 2002, the entire specifications of both of which are expressly incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention generally relates to the control of the output of a variable flow pump, and more specifically to control systems for an oil pump for oil pressure control in an internal combustion engine, transmission, and/or the like. 
   BACKGROUND OF THE INVENTION 
   It is desirable to properly lubricate the moving components in an internal combustion engine and provide hydraulic power. Typically, oil pumps used in engines are operably associated with the crankshaft of the engine (e.g., direct driven, chain driven, gear driven and/or the like) and have relatively simple fixed pressure regulation systems. While these systems are generally adequate, there are some disadvantages. For example, there is not much control of the actual discharge pressure relative to the pressure needed by the engine under certain/given operating conditions. By way of a non-limiting example, currently available pump technology typically provides high oil pressure at all engine operating conditions, where a lower oil pressure may be adequate at some of those engine conditions. 
   In commonly-assigned U.S. Pat. No. 6,896,489, the entire specification of which is expressly incorporated herein by reference, a mechanical hydraulic arrangement is shown for providing control of a variable displacement vane pump. This provides for a more optimized control of engine oil pressure. However, it is yet desirable to provide some further control depending on engine needs and/or variables. 
   Accordingly, there exists a need for a method of control and system for control of a variable flow pump (e.g., vane pump) by the use of an engine control unit which actuates a solenoid for directly and/or indirectly controlling the flow rate of a variable flow pump. 
   SUMMARY OF THE INVENTION 
   In accordance with the general teachings of the present invention, a control system for a variable flow hydraulic pump is provided, wherein electrical input from an engine control unit actuates a solenoid for controlling the engine oil pressure to the desired level under a wide range of operating conditions. 
   In accordance with a first embodiment, a pump system including a control system for controlling a variable flow pump for controlling oil flow and oil pressure in a hydraulic circuit in an engine is provided, comprising: (1) a pump member; (2) an actuating member capable of controlling the flow generated by the pump member; and (3) a solenoid valve system including a solenoid valve portion and a pressure regulator valve portion, wherein the solenoid valve system is operably associated with the pump, wherein the pressure regulator valve portion is operably associated with the actuating member for selectively controlling the flow generated by the pump member. 
   In accordance with a second embodiment, a pump system including a control system for controlling a variable flow pump for controlling oil flow and oil pressure in a hydraulic circuit in an engine is provided, comprising: (1) a pump member; (2) an actuating member capable of controlling the flow generated by the pump member; (3) a solenoid valve system including a solenoid valve portion and a pressure regulator valve portion, wherein the solenoid valve system is operably associated with the pump member, wherein the pressure regulator valve portion is operably associated with the actuating member for selectively controlling the flow generated by the pump member; and (4) an electronic control unit operably associated with the solenoid valve portion, wherein the electronic control unit is selectively operable to provide an input control signal to the solenoid valve portion for controlling oil flow and oil pressure. 
   In accordance with a third embodiment, a pump system including a control system for controlling a variable flow pump for controlling oil flow and oil pressure in a hydraulic circuit in an engine is provided, comprising: (1) a pump member; (2) an actuating member capable of controlling the flow generated by the pump member, wherein the pump member is a vane pump and the actuator member is at least part of an eccentric ring of the vane pump, wherein the vane pump and the eccentric ring operate to control the flow of oil to the engine; (3) a solenoid valve system including a solenoid valve portion and a pressure regulator valve portion, wherein the solenoid valve system is operably associated with the pump member, wherein the pressure regulator valve portion is operably associated with the actuating member for selectively controlling the flow generated by the pump member; and (4) an electronic control unit operably associated with the solenoid valve portion, wherein the electronic control unit is selectively operable to provide an input control signal to the solenoid valve portion for controlling oil flow and oil pressure. 
   In accordance with one aspect of the present invention, an electronic control unit is operably associated with the solenoid valve portion, wherein the electronic control unit is selectively operable to provide an input control signal to the solenoid valve portion for controlling oil flow and oil pressure. 
   In accordance with one aspect of the present invention, the electronic control unit is operably associated with and monitors the pressure in a portion of the hydraulic circuit, wherein the electronic control unit generates an input signal to the solenoid valve portion in response to pressure conditions in the portion of the hydraulic circuit for controlling flow generated by the pump member. 
   In accordance with one aspect of the present invention, the electronic control unit monitors engine conditions selected from the group consisting of engine speed, engine temperature, engine load, and combinations thereof, and selectively adjusts oil pressure based thereon. 
   In accordance with one aspect of the present invention, the pump member is a vane pump and the actuator member is at least part of an eccentric ring of the vane pump, wherein the vane pump and the eccentric ring operate to control the flow of oil to the engine. 
   In accordance with one aspect of the present invention, the solenoid valve system is disposed within a housing member. 
   In accordance with one aspect of the present invention, the solenoid valve system is operable to regulate a supply pressure down to a control pressure. 
   In accordance with one aspect of the present invention, the solenoid valve system is selectively operable to regulate a supply pressure down to a control pressure in response to the current supplied to the solenoid valve portion. 
   In accordance with one aspect of the present invention, a first biasable member is operably associated with the actuating member, wherein the first biasable member is selectively operable to cause the actuating member to control the flow generated by the pump member. 
   In accordance with one aspect of the present invention, the pressure regulator valve portion comprises a flow control spool valve, wherein the flow control spool valve is operably associated with the solenoid valve portion, wherein the flow control spool valve is selectively operable to control flow to the actuating member. 
   In accordance with one aspect of the present invention, a second biasable member is operably associated with a first end of the flow control spool valve, wherein the second biasable member maintains pressure on the flow control spool valve during regular operation, and provides return pressure on the flow control spool valve in the presence of low supply pressure conditions. 
   In accordance with one aspect of the present invention, the oil pressure can be controlled at a plurality of locations in the hydraulic circuit by applying the oil pressure to the actuating member. 
   In accordance with one aspect of the present invention, the plurality of locations is selected from the group consisting of a point within the pump, a point of the pump discharge to the engine, a point within the engine main oil gallery, and combinations thereof. 
   In accordance with one aspect of the present invention, the oil pressure can be supplied to the solenoid valve system from a plurality of locations in the hydraulic circuit. 
   In accordance with one aspect of the present invention, the plurality of locations is selected from the group consisting of a point within the pump, a point of the pump discharge to the engine, a point within the engine main oil gallery, and combinations thereof. 
   In accordance with one aspect of the present invention, the solenoid valve portion can be selectively actuated by a technique selected from the group consisting of electrical actuation, hydraulic pressure actuation, and combinations thereof. 
   In accordance with one aspect of the present invention, the solenoid valve system comprises a variable force solenoid. 
   A further understanding of the present invention will be had in view of the description of the drawings and detailed description of the invention, when viewed in conjunction with the subjoined claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  illustrates a hydraulic schematic of a variable displacement pump system, in accordance with the general teachings of the present invention; 
       FIG. 2  illustrates a sectional view of a pump element, in accordance with a first embodiment of the present invention; and 
       FIG. 3  illustrates a graph showing the performance characteristics of a solenoid valve module, in accordance with a second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The following description of the invention is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   Referring to drawings generally, and specifically to  FIGS. 1 and 2 , a system and method is provided for controlling an oil pump  40  with either a variable displacement pump element or a variable output pump element. It should be appreciated that other types of pump systems can be used in the present invention, such as but not limited to other types of vane pumps, gear pumps, piston pumps, and/or the like. 
   In the engine system of the present invention, there is at least a lubrication circuit  10 , an oil sump  20 , an engine control unit (i.e., ECU) or computer  30 , and an oil pump  40  which draws oil from the oil sump  20  and delivers it at an elevated pressure to the lubrication circuit  10 . 
   In accordance with one aspect of the present invention, the lubrication circuit  10  includes at least an oil filter  11  and journal bearings  12  supporting the engine&#39;s crankshaft, connecting rods and camshafts, and can contain a variable pressure transducer  13  and/or an oil cooler  14 . The lubrication circuit  10  can also optionally contain items such as piston cooling jets, chain oilers, variable cam timing phasers, and cylinder de-activation systems, as are generally known in the art. 
   In accordance with one aspect of the present invention, the ECU  30  includes electrical inputs for the measured engine speed  31 , engine temperature  32 , and engine load, torque or throttle  33 . The ECU  30  can also have an electrical input for the measured oil pressure  34  from the transducer  13 . The ECU  30  also has an output  35  for an electrical control signal to the oil pump  40 . 
   In accordance with one aspect of the present invention, the oil pump  40  includes a housing  41  which contains a suction passage  42 , and a discharge passage and manifold  43 . The oil pump  40  can also include a pressure relief valve  44  and/or an internal oil filter  45  for cleaning the discharge oil for use inside the oil pump  40 . 
   In accordance with one aspect of the present invention, the oil pump  40  contains a variable flow pump element  50 , which is further comprised of a positionable element, such as an eccentric ring  51 , the position of which determines the theoretical flow rate discharged by the pump element  50  at a given drive speed, and which forms in conjunction with the housing  41  two control chambers on opposing sides of the eccentric ring  51 , which contain fluid of controlled pressure for the intended purpose of exerting a control force on an area of the eccentric ring  51 . The first chamber, e.g., the decrease chamber  52 , contains pressure applied to the eccentric ring  51  to decrease the flow rate of the variable flow pump element  50 , and the second chamber, e.g., the increase chamber  53 , contains pressure applied to the eccentric ring  51  to increase the flow rate of the variable flow pump element  50 . There is additionally a spring  54  positioned between the housing  41  and the eccentric ring  51  which applies a force to the eccentric ring  51  to increase the flow rate of the variable flow pump element  50 . The decrease chamber  52  can be supplied with oil pressure from either the oil pump discharge manifold  43  via channel  56  or some other point downstream in the lubrication circuit  10  (e.g., usually from the main oil gallery  15 ) via channel  55 . 
   In accordance with one aspect of the present invention, the oil pump  40  also contains a solenoid valve module  60  which includes a solenoid valve stage  70  and a pressure regulator valve stage  80 . 
   In accordance with one aspect of the present invention, the solenoid valve stage  70  includes a solenoid  71 , a spring  72 , and a housing  73 . The solenoid  71  includes a coil of electrical wire  74  and a ferrous armature  75 , configured so that an electric current passing through the coil  74  generates an electromagnetic field which moves the armature against the compression spring  72  and opens the valve hole  76  in the housing  73 , thereby allowing fluid to flow through it. 
   In accordance with one aspect of the present invention, the pressure regulator valve stage  80  includes a spool  81 , a spring  82 , and an area defining a bore  83  (i.e., in housing  73 ) for radial containment of the spool  81 . The spool  81  has in its outer diameter two annular grooves, a spool supply port  84  which is in continuous fluid communication with the housing supply port  86 , and a spool control port  85  which is in continuous fluid communication with the housing control port  87 . Housing supply port  86  can be supplied with oil pressure from either the oil pump discharge manifold  43  via filter  45  and channel  62  or some other point downstream in the lubrication circuit  10  (e.g., usually from the main oil gallery  15 ) via channel  61 . The spool supply port  84  is also in continuous fluid communication with fluid chamber  89  via the restrictive orifice hole  88 . The spool control port  85  is also in continuous fluid communication with fluid chamber  90  via hole  91 . The spool  81  is positioned axially in bore  83  by the resultant force of the control pressure in fluid chamber  90 , the spring  82 , and the supply pressure in fluid chamber  89 . 
   A change in the axial position of spool  81  will increase or reduce the area open for fluid communication between spool control port  85  and both housing supply port  86  and housing drain port  92 , which has the resultant effect of regulating the control pressure (e.g., see reference  61  in  FIG. 3 ) in spool control port  85  and passage  87  to some level lower than the pressure in supply passage  86  (e.g., see reference  62  in  FIG. 3 ). The lower pressure level is determined by the spring rate and assembled length of spring  82  and the area at each end of spool  81 . The lower pressure level is supplied to the increase chamber  53  through passage  87  where it acts on the eccentric ring  51  along with the spring  54  to increase the flow rate of the variable flow pump element  50 . The lower pressure level serves as a reference force for the eccentric ring  51 , along with spring  54 , so that if the pressure in the decrease chamber  52  exceeds them, the pressure in the decrease chamber  52  will move the eccentric ring  51  to reduce the pump flow, which will reduce the pressure in the decrease chamber  52  until it is in force equilibrium with the pressure in increase chamber  53  and the spring  54 . 
   Conversely, if the pressure in the decrease chamber  52  is lower than the reference pressure, the pressure in the increase chamber  53  and the spring  54  will move the eccentric ring to increase the pump flow. The pressure regulator valve stage  80  is shown in accordance with one aspect of the present invention to have a total of three fluid communication ports, i.e., the supply port  84 , the control port  86  and the drain port  92 . 
     FIG. 3  graphically illustrates the solenoid valve control pressure  61  (e.g., in port  85  and passage  87 ) on the vertical axis as a function of both the supply pressure  62  (e.g., in port  84  and passage  86 ) on the horizontal axis and the current to the solenoid valve  70  through the ECU electrical output line/wire  35 . 
   In accordance with one aspect of the present invention, the curves have three characteristic zones, e.g., the zero control pressure zone  63 , the offset control pressure zone  64 , and the variable control pressure zone  65 . The zero control pressure zone  63  is identical for all currents to the solenoid valve  70 . The transition from the offset control pressure zone  64  to the variable control pressure zone  65  occurs at decreasing supply pressure as the current to the solenoid valve  70  is increased. The pressure regulating stage  80  has a characteristic offset  66  between the supply pressure  62  and the control pressure  61 . Without being bound to a particular theory of the operation of the present invention, it is believed that this offset  66  is the reason that there is a zero control pressure zone  63  because the supply pressure  62  has not yet reached the level of the offset  66 , and the control pressure  61  cannot be negative (e.g., a vacuum). 
   At low supply pressure  62 , the spring  82  holds the spool  81  to the right in dominance over the supply pressure  62  acting on the end of spool  81  from fluid chamber  89  via restrictive passage  88 , thereby closing the area of fluid communication between the supply port  84  and the control port  86  and opening the area of fluid communication between the control port  86  and the drain port  92 . As the supply pressure  62  increases, it will move the spool  81  to the left against the spring  82  and will eventually close the area of fluid communication between the control port  86  and the drain port  92 , at which point the pressure can begin to build in the control port  86  via leakage between the spool  81  and the housing bore  83  from the supply port  84  to the control port  86 . As the supply pressure  62  continues to increase, it will further move the spool  81  to the point where the area of fluid communication between the supply port  84  and the control port  86  is opened, allowing the control pressure  61  to rise to the level of the supply pressure  62 . At that point, the spring force  82  together with the control pressure force in fluid chamber  90 , e.g., communicated via passage  91 , will overcome the supply pressure force in fluid chamber  89  and move the spool  81  to the right. The spool  81  will reach an equilibrium position where the control pressure force is reduced from the supply pressure force by the amount of the force applied to the spool  81  by the spring  82 , which thereby determines the characteristic offset  66  in the offset control pressure zone  64 . 
   As the supply pressure  62  continues to increase, the pressure in fluid chamber  89  will follow, and it can eventually overcome the spring  72  holding the solenoid armature  75  against the housing  73 , thereby opening valve hole  76  and attenuating further increase of the supply pressure  62 . When the valve hole  86  is open, and there is a restricted fluid flow through the restrictive passage  88 , the pressure in fluid chamber  89  is no longer equal to, but is reduced from, the supply pressure  62  at the supply port  84 . When the ECU  30  selectively routes current through the solenoid coil  74  via electrical output  35 , the solenoid armature  75  is also forced to the right against the spring  72  by the resulting electromagnetic field, which will also serve to reduce the pressure in fluid chamber  89  and thereby the control pressure  61 . The spring  72  provides a proportional characteristic to the solenoid valve system, such that increasing current provides increasing valve opening, e.g., a variable force solenoid. The control pressure  61  will maintain its characteristic offset  66  to the pressure in fluid chamber  89 , which is reduced from the supply pressure  62  because of the restricted flow through passage  88 . 
   In accordance with one aspect of the present invention, the oil pump  40  can be operated without the ECU  30 , because the solenoid valve module  60  performs some pressure regulation activity even without electrical power, as shown in the third operating zone  65  in  FIG. 3 . 
   In accordance with one aspect of the present invention, the oil pump  40  can be operated by the ECU  30  in an open loop control mode because the ECU  30  can be reasonably certain of the oil pressure in the lubrication circuit  10  as a function of current to the solenoid  71  through electrical output  35  from an internal “look up” table in the ECU  30 , even without measuring the oil pressure through transducer  13 . 
   In accordance with one aspect of the present invention, the oil pump  40  can be operated by the ECU  30  in a closed loop mode to actively control the oil pressure by adjusting its electrical signal to the solenoid  71  through electrical output  35  according to software logic control programmed into the ECU  30  and the oil pressure measured in the lubrication circuit  10  by transducer  13 . The ECU  30  can also anticipate increasing oil demand in the lubrication circuit  10 . This can be accomplished by simultaneously actuating the pump and an oil-consuming engine subsystem, such as variable cam timing or cylinder deactivation. The ECU  30 , through the present invention, would also have the capability of selectively activating certain pressure-sensitive engine subsystems, by selecting a higher or lower oil pressure for the lubrication circuit  10  depending on any known condition, including but not limited to the measured engine speed  31 , engine temperature  32 , and/or engine load  33 . 
   In accordance with one aspect of the present invention, the oil pump  40  can be operated in a mixed control mode by combining elements of the previous three control modes. By way of a non-limiting example, it could be useful to allow the oil pump  40  to regulate itself without ECU control at conditions outside the range of normal parameters, and then to use open loop control to quickly achieve oil pressure near the desired value, and then use closed loop control to exactly achieve the desired oil pressure. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the scope of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Technology Classification (CPC): 5