Abstract:
An electrically operated valve controls the flow of oil to and from a device that activates and deactivates a cylinder of a multi-cylinder engine. A first valve seat is between an inlet and a workport connected to the device and a second valve seat is between the workport and an outlet. A valve element engages the first valve seat when a solenoid actuator is energized. The valve element and the first valve seat cooperate to allow air to bleed from the inlet through the valve upon starting the engine, but prevent the oil from flowing in that path unless the solenoid actuator is energized. In one version of the valve, the valve element engages the second valve seat when disengaged from the first valve seat. In a second version, another valve element engages the second valve seat when oil flows through the first valve seat.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electrohydraulic valves, and more particularly to such valves that control operation of intake and exhaust valves of a multi-cylinder internal combustion engine to selectively activate and deactivate or otherwise control operation of selected cylinders. 
     2. Description of the Related Art 
     In an effort to improve fuel economy, automobile manufacturers have devised systems that deactivate selected cylinders of an engine when the full power produced by all the cylinders is not required. For example, the “V-8-6-4 engine” is able to switch between four, six and eight cylinder operation. The selection of which cylinders to deactivate is determined by engine firing order with the desire to keep an even firing order in the deactivated mode. Several modes of cylinder deactivation are possible. In a bank mode, the multiple cylinders in the same bank of a V-configuration engine are switched at the same time, whereas each cylinder is switched independently in the cylinder control mode. A given cylinder is activated and deactivated by controlling the operation of the intake valves for that cylinder. By disabling the intake valve or valves for a given cylinder, the air-fuel mixture does not enter that cylinder and thus combustion does not occur. The exhaust valve also may be disabled in a similar manner. 
     The engine cylinder valve operation is controlled by a solenoid activated hydraulic valve which governs the flow of pressurized engine lubricating oil to a cylinder valve actuator. When the solenoid valve is energized, pressurized engine oil is applied from a workport of that valve to operate a spring-biased locking pin inside the cylinder valve lifter, which effectively decouples the cam shaft from the cylinder valve. When the solenoid is de-energized, the solenoid valve&#39;s workport is connected to the engine oil pan releasing the pressure at the cylinder valve actuator, which results in a spring biasing the locking pin to activate the intake or exhaust valve. Alternatively, the locking pin for the cylinder valve lifter can be configured so that energizing and de-energizing the solenoid valve has the opposite effects. 
     It is desirable to control the switching of the engine cylinder valves in less than one engine cycle. Therefore, the solenoid valve must respond very quickly in order to ensure timely deactivation and reactivation of the engine cylinder valve. Thus, it is desirable that the solenoid valve is required to generate as little force as possible thereby minimizing operating time. 
     When the engine is turned off, the lubricating oil that was used to control the engine cylinder valves drains into the oil pan and air enters the conduits of the valve control system. Therefore mechanism for bleeding the air from the system upon starting the engine has to be provided. 
     Because several solenoid activated hydraulic valves are require, it is desirable to provide a valve assembly which facilitates positioning and attaching those valves to the engine. In addition the valve assembly should be highly immune to vibrations, temperature changes and fluid exposure. 
     SUMMARY OF THE INVENTION 
     An electrohydraulic valve for a hydraulic system is provided to control operation of intake and exhaust valves of a multi-cylinder engine. The electrohydraulic valve has a valve body with a bore into which an inlet, an outlet and a workport open. The bore has a first valve seat between the inlet and workport and a second valve seat between the workport and the outlet. A mechanically unbiased valve element is movably located in the bore for selectively engaging and disengaging the first valve seat to close communication between the inlet and the workport. The valve element and first valve seat are so constructed that when the engine starts, air in the hydraulic system is able to bleed from the inlet past the first valve seat regardless of whether the cylinder valve is active or de-active. 
     An actuator has an electromagnetic coil into which an armature is slidably received. A stem projects from the armature to selectively disengage and move the valve element out of engagement with the first valve seat against pressure at the inlet. 
     In a first embodiment of the electrohydraulic valve, a second valve element is connected to the armature. The second valve element engages the second valve seat to close communication between the workport and the outlet when the first valve element is disengaged from the first valve seat. A spring is incorporated which applies a force that tends to move the second valve element away from the second valve seat and the stem away from the first valve element. Air in the hydraulic system, when the engine starts, is able to flow from inlet through the first valve seat without forcing valve element against the first valve seat. However, more viscous hydraulic oil entering the inlet forces the valve element against the first valve seat unless the actuator is holding the valve element away. 
     In a second embodiment of the electrohydraulic valve, a tubular member is slidably received within the bore between the inlet and a lip in the bore. The first valve seat is formed on an end of the tubular member that faces the workport. The valve element alternately engages the first and second valve seats. In this version of the valve when the multi-cylinder engine starts, air in the hydraulic system is able to flow from inlet around the tubular member to the outlet while the valve element engages the first valve seat. Upon exhaustion of air from the hydraulic system, pressure from oil at the inlet forces the tubular member against the lip of the bore thereby closing a path around the tubular member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of an assembly of electrohydraulic valves according to the present invention; 
         FIG. 2  is a side view of the valve assembly; 
         FIG. 3  is a top view of a base plate in the valve assembly; 
         FIGS. 4 ,  5 , and  6  are top, side and end views, respectively, of and electrical lead subassembly incorporated into the electrohydraulic valve assembly; 
         FIG. 7  is an enlarged side view of a section of the electrical lead subassembly; 
         FIG. 8  is an enlarged top view of the section of the electrical lead subassembly; 
         FIG. 9  is a cross section view along line  4 — 4  in  FIG. 2  through one of the electrohydraulic valves; and 
         FIG. 10  is a cross section view through another embodiment of an electrohydraulic valve. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIGS. 1–3 , a valve assembly  10  has a thin, planar base plate  12  fabricated of metal with three openings  14 ,  15  and  16  extending between two opposing major surfaces  17  and  18 . Three electrohydraulic valves  21 ,  22  and  23  are located in the three openings  14 ,  15  and  16 , respectively. The base plate  12  is dimensioned to attach to a manifold  25  of an multi-cylinder engine wherein the bodies of the three electrohydraulic valves  21 – 23  that extend beneath the base plate enter apertures in the manifold. Each base plate opening  14 – 16  is slightly larger that the outer dimension of electrohydraulic valve enabling the valve to move freely in two orthogonal axes on a major surface  17  or  18  of the base plate  12 . As will be described, this loose attachment allows each electrohydraulic valve to seat itself in the respective manifold aperture and accommodate dimensional irregularities of the components when the valve assembly  10  is mounted to the engine. A pair of prongs  24  project from opposite sides toward the center of each base plate opening  14 – 16 . The distance between the prongs  24  is slightly larger than the outer dimension of outer metal cap  26  of the electrohydraulic valve  21 – 23 . The edge of the outer cap  26  which abuts the base plate  12  has a pair of tabs  28  which project through the opening  14 ,  15  or  16  and are loosely bend against the underside side of the base plate. Until the valve assembly  10  is attached to the engine, the tabs  28  do not restrict movement of the three electrohydraulic valves  21 ,  22  and  23  with respect to the base plate  12 . 
     An electrical lead frame  30  has a foot  31  with a pin  38  that projects through an aperture  39  to the base plate  12  and has a mounting aperture  36  that aligns with a hole  37  in the base plate  12  (see  FIG. 3 ) to receive a bolt as will be described. The electrical lead frame  30  has a connector post  32  projecting from the foot  31  away from the base plate  12 . The lead frame  30  also has a thin, flexible bar  34  that is cantilevered from the foot  31  and connector post  32  along one longitudinal edge of the base plate  12 . The flexible bar  34  is not directly connected to the base plate  12 . The foot  31 , connector post  32  and flexible bar  34  are fabricated from plastic that is molded around a set of electrical leads that extends from an electrical connector  35  at the end of the connector post to pairs of terminals  46 – 49  adjacent the electrohydraulic valves  21 – 23 . The electrical connector  35  receives a mating connector on an end of a cable that extends from the engine computer. 
     The connection of the lead frame  30  to each electrohydraulic valve  21 – 23  prevents the valves from falling downward through the base plate  12  in  FIG. 2 . The outwardly projecting pair of tabs  28  prevents each electrohydraulic valve  21 – 23  from passing upward through the base plate  12 . This holds the valve assembly  10  together prior to being attached to an engine. 
     With reference to  FIGS. 4–6 , the set of electrical leads  40  is stamped as a unit from a flat sheet of brass, although other metals may be used. The stamping is then bend into the form illustrated in the drawings. The resultant structure has four parallel, coplanar conductors  41 ,  42 ,  43  and  44 , which are initially joined together by thin ties  45 . The first conductor  41  is connected in common to all three electrohydraulic valves  21 – 23 , while each of the other three conductors  42 ,  43  and  44  is connected to only one of the valves. Thus the first conductor  41  has three terminals  46 , one adjacent each valve location (see  FIG. 1 ). The second conductor  42  has a terminal  47  adjacent the first electrohydraulic valve  21  and a terminal  48  of the third conductor  43  is near the second electrohydraulic valve  22 . The fourth conductor  44  has a terminal  49  adjacent the third electrohydraulic valve  23 . 
     Each conductor  41 ,  42 ,  43  and  44  is joined to an end of a different L-shaped leg  50 ,  51 ,  52  or  53 , respectively, which are in a plane perpendicular to the plane of the conductors. The other ends of the L-shaped legs  50 ,  51 ,  52  and  53  are connected to four contacts  54 ,  55 ,  56  and  57 , respectively, which are in a plane perpendicular to the planes of the L-shaped legs and the conductors. 
     As seen in  FIGS. 4 and 5 , the second conductor  42  has a bridge  59  which crosses over an arm  41   a  of the first conductor  41  that extends to the terminal  46  for the second electrohydraulic valve  22 . The details of this cross over are shown in the rear view this portion of the set of electrical leads  40  in  FIG. 7  and also in the enlarged top view in  FIG. 8 . The second conductor  42  has a gap thereby segmenting the conductor into two aligned sections  42   a  and  42   b . The arm  41   a  of the first conductor  41  extends through that gap (see  FIG. 5 ). A pair of U-shaped couplings  58  each have one end extending from a different section  42   a  or  42   b  of the second conductor  42 . The other ends of the couplings  58  are spaced from the plane of the conductors  41 – 44  and a bridge  59  extends between those other ends. In the assembled electrical lead frame  30 , the plastic of the flexible bar  34  maintains the bridge  59  spaced from the conductors  41 – 44 . 
     Referring again to  FIGS. 1 and 2 , when the plastic is molded around the set of electrical leads  40 , the four parallel, conductors  41 – 44  are encased in the flexible bar  34 , the L-shaped legs  50 – 53  are in the foot  31 , and the four contacts  54 – 57  are in the connector post  32 . When the mold closes, its elements hold the in the conductors  41 – 44  in place and sever the ties  45  between the conductors  41 ,  42 ,  43  and  44  prior to the plastic being injected into the mold. 
     The Electrohydraulic Valves 
     The construction of the first electrohydraulic valve  21  in the assembly  10  is illustrated in  FIG. 9  with the understanding that the other two valves  22  and  23  are identical to the first one. The first electrohydraulic valve  21  has valve body  60  that fits into the engine manifold  25  when the valve assembly  10  is mounted on the engine. This valve  21  has a longitudinal bore  62  extending through a valve body  60 . An inlet  64  of the bore  62  at valve nose opens into a supply gallery  65  of the engine manifold through which pressurized lubricating oil flows, and a transverse outlet  66  provides a path between the bore and a return gallery  67  in the engine manifold that leads to the oil pan. Between the inlet  64  and outlet  66  along the valve body  60  is a workport  68  providing a path between the bore and a manifold gallery  69  that leads to the cylinder valve actuator. A plurality of sealing rings extend externally around the valve body  60  to engage internal walls of the engine manifold  25 . 
     An annular plug  70  is secured in the opening of the bore  62  and forms the valve inlet  64 . A first valve seat  74  is formed in the bore between the valve inlet  64  and the workport  68 . A first valve element  76 , in the form of a sphere, is captivated in a chamber  72  of the bore  62  located between the plug  70  and a first valve seat  74 . The first valve element  76  is mechanically unbiased and able to move freely in the chamber  72  in response to fluid pressure. A second valve seat  78  is formed in the bore  62  between the workport  68  and the outlet  66 . 
     A second valve element  80 , in the form of a poppet, is slidably received within the bore  62  of the valve body  60  and selectively engages the second valve seat  78  to control fluid flow between the workport  68  and the outlet  66 . A spring  85  biases the second valve element  80  away from the second valve seat  78 . A stem  82  projects from the second valve element  80  toward the first valve member. The second valve element  80  is attached to and operated by an armature  86  of a solenoid actuator  84 . The second valve element  80 , the stem  82 , and the armature  86  preferably are fabricated as a single piece. 
     The solenoid actuator  84  also includes an electromagnetic coil  88  wound on a bobbin  90  that has a central aperture through which the armature  86  extends. A pair of terminals  91  for the electromagnetic coil  88  extend horizontally outward (see also  FIG. 1 ) and are resistance welded to the terminals  46  and  47  on the lead frame  30 . The electromagnetic coil  88  and the bobbin  90  are contained within the metal cap  26  which has an open end closed by a magnetic pole piece  94  and the valve body  60  that is secured to the cap. The magnetic pole piece  94  has a circular rim  95  which fits into the opening of the bore  62  at the interior end of the valve body  60 . This circular rim  95  aids in aligning the solenoid actuator  84  with the body  60  during assembly of the valve  21 . 
     The cap  26  has a vent aperture  96  through which oil that leaks past the armature escapes from the cap and into the engine. Typically the valve assembly  10  is located beneath the engine valve cover so that the escaping lubricating oil is contained to flow through the engine and into the oil pan. The metal valve cap  26  has a tongue  98  which extends from one side and is bent around the lead frame  30  to secure those components together. 
       FIG. 9  illustrates the first electrohydraulic valve  21  in the energized state in which electric current is being applied to the electromagnetic coil  88  of the solenoid actuator  84 . This creates a magnetic field that drives the armature  86  farther into the valve body  60 . This movement forces the second valve element  80  against the first valve seat  78  thereby closing a fluid path between the workport  68  and the outlet  66 . Motion of the armature  86  also causes the stem  82  to push the first valve element  76  away from the first valve seat  74  which opens a path between the inlet  64  and the workport  68 . In this state of the first electrohydraulic valve  21 , pressurized lubricating oil is applied through the workport  68  to the cylinder valve actuator and deactivates the engine cylinder valve. 
     When the electric current is removed from the electromagnetic coil  88 , the spring  85  and hydraulic pressure forces the second valve element  80  away from engagement with the second valve seat  78 . As a result a fluid path is opened between the workport  68  and the outlet  66 . This motion also moves the stem  82  away from the first valve element  76  which allows the pressure at the inlet  64  to move the first valve element into engagement with the first valve seat  74  thus closing the path between the inlet  64  and the workport  68 . This position of the first electrohydraulic valve  21  releases the pressure previously applied to the cylinder valve actuator and activates the associated engine cylinder. 
     When the engine is turned off, the first electrohydraulic valve  21  is de-energized. The force of the spring  85  moves the second valve element  80  away from the second valve seat  78  and the stem  82  away from the first valve element  76  thereby releasing any fluid pressure at the workport  68 . Initially pressure at the valve inlet  64  holds the first valve element  76  against the first valve seat  74 . Eventually the inlet pressure decreases to the atmospheric pressure level. When that pressure equalization occurs the first valve element  76  drops away from the first valve seat  74  due to gravity and lubricating oil in the passages of the engine drains into the oil pan. This introduces air into the first electrohydraulic valve  21  and the galleries of the engine manifold. 
     When the engine is restarted, the air within the manifold supply gallery is forced to the valve inlet  64  by lubricating oil from the now operating oil pump of the engine. Initially all the engine cylinders are active wherein the first electrohydraulic valve  21  is de-energized so that the second valve element  80  is away from the second valve seat  78  and the stem  82  is disengaged from the first valve element  76 . However, the relative low viscosity of the air flowing through the inlet  64  is insufficient to produce a great enough pressure differential to move the spherical first valve element  76  fully upward against the first valve seat  74 . As a result, the air bleeds from the inlet  64  through the second valve seat  78  and into the outlet  66  from which the air flows to a chamber underneath the engine valve cover. Some lubricating oil flows past the first valve seat  74  and displaces air in the gallery connected to the workport  68 . Eventually all the air from the supply gallery is forced through the inlet  64  and the more viscous lubricating oil creates a significantly great pressure differential which applies sufficient force to move the first valve element  76  against the first valve seat  74 . Thus air is automatically bled from the hydraulic system. Therefore, the present electrohydraulic valve incorporates a mechanism that automatically bleeds air from the hydraulic system for activating and deactivating the engine cylinders. 
       FIG. 10  illustrates a second embodiment of an electrohydraulic valve  100  according to the present invention and which has valve body  101  with a longitudinal bore  102  extending there through. The valve body  101  has an inlet  104  at an exposed end of the bore  102 , a transverse outlet  106 , and a transverse workport  108  between the inlet and outlet. A first valve seat  110  is formed on a tubular member  111  that is slidably received within the bore between the valve inlet  104  and the workport  108 . A second valve seat  114  is formed in the bore  102  between the workport  108  and the outlet  106 . A spherical valve element  112  is captivated in the bore  102  and selectively engages the first and second valve seats  110  and  114  one at a time. 
     The spherical valve element  112  is operated on by a stem  120  that projects from an armature  118  that is part of the solenoid actuator  122 . The armature  118  is biased into engagement with the spherical valve element  112  by a spring  126  and is driven away from the spherical valve element by the magnetic field produced by an electromagnetic coil  124 . The first magnetic pole piece  128  is fixedly secured within a metal cap  130  of the solenoid actuator  122  extending into the electromagnetic coil  124 . Both the first magnetic pole piece  128  and the cap  130  have apertures  132  and  134  to allow oil that leaks past the armature  118  to escape from the valve  100 . The metal cap  130  has an open end that is closed by a second annular magnetic pole piece  136  and the valve body  101  to which the cap is secured. 
     The metal cap  130  of the solenoid actuator  122  has a tongue  140  which extends from one side and is bent around the lead frame  30 . Electrical terminals  142  of the electromagnetic coil  124  are resistance welded to terminals of the lead frame  30  thereby electrically connecting the valve  100  to the engine computer. 
     In the de-energized state of the electrohydraulic valve  100 , the force of the spring  126  is greater than the force exerted by pressure at the inlet  102 . Therefore, the armature  118  is moved downward in the drawings wherein the stem  120  pushes the spherical valve element  112  against the first valve seat  110  which in turn slides the tubular member  111  against stops at the inlet  104 . In this state, the spherical valve element  112  abutting the first valve seat  110  effectively blocks flow of oil from the inlet  104 . However, oil is able to flow from the workport  108  past the stem  120  and armature  118  to the outlet  106 . Therefore, pressure is relieved at the workport  108 , thereby causing the cylinder valve actuator to activate the engine cylinder. 
     When the engine is turned off, the pressure in the hydraulic system equalizes at the atmospheric pressure level. When this occurs, gravity causes the tubular member  111  and the spherical valve element  112  to drop against stops at the inlet  104 . When the engine is restarted, air in the valve hydraulic system flows into the valve inlet  104  and through small gap between the outer surface of the tubular member  111  and the bore  102 . This air flow continues to the valve outlet  106  from which it is exhausted from the system. The relatively low viscosity of the air does not create a great enough pressure differential to apply significant force to move the tubular member  111  away from the inlet  104 . When lubricating oil, which has a greater viscosity than air, reaches the inlet  104 , the tubular member  111  is forced upward against a lip  116  in the bore  102  which seals the gap between the tubular member and the bore. The force of the pressurized oil, that now is applied to the surface area of the spherical valve element  112  exposed in the central opening through the tubular member  111 , is insufficient to counteract the spring force and unseat the valve element from the first valve seat  110 . 
     When the electrohydraulic valve  100  is energized, the magnetic field produced by the electromagnetic coil  124  draws the armature upward against the force of spring  126 . This action moves the stem  120  away from the spherical valve element  112 , which then is forced by the inlet oil pressure away from the first valve seat  110  and against the second valve seat  114 . In this state, pressurized lubricating oil flows from the inlet  104  through the workport  108  to deactivate the engine cylinder valve. The spherical valve element  112  abutting the second valve seat  114  prevents oil from flowing to the outlet  106 . 
     Fabricating of the Valve Assembly 
     Prior to mounting each electrohydraulic valve  21 – 23  on the base plate  12 , the tongue  98  of the metal valve cap  26  has an large upper opening. The valve assembly  10  is constructed by inserting the three electrohydraulic valves  21 – 23  upward into the respective openings  14 – 16  in the base plate  12  until the tabs  28  abut the underside of the base plate. The relatively large size of the openings  14 – 16  able the valves  21 – 23  to move along the two orthogonal axes of the plane of the base plate  12 . 
     Next the flexible bar  34  of the electrical lead frame  30  is inserted between the main part of each valve&#39;s cap  26  and the tongue  98 . As this occurs the pin  38  on the lead frame foot  31  passes into the aperture  39  in the base plate  12 . The tips of the tongues  98  then are bend over the upper edge of the flexible bar  34  to secure the three electrohydraulic valves  21 – 23  to the electrical lead frame  30 . At this point the electrohydraulic valves  21 – 23  are captivated in the assembly by the connection to the lead frame  30  and the outwardly projecting valve tabs  28 , thereby holding the valve assembly  10  together prior to being attached to an engine. 
     When the valve assembly is mounted on the engine manifold  25 , the bodies  60  of the three electrohydraulic valves  21 – 23  are inserted into separate openings in the manifold. The pin  38  on the lead frame connector post  32  that projects through the base plate  12  enters a locating aperture in the manifold to position the base plate. Bolts  148  are placed through apertures  150  in the base plate  12  and into threaded holes in the manifold  25 . As the bolts  148  are tightened, the electrohydraulic valves are pushed farther into the manifold openings. The loose engagement of the valves with the base plate  12  allows each valve to move with respect to the base plate and properly seat in the respective opening. The cantilevered bar  34  of the lead frame  30  flexes to allow each valve  21 – 23  to move in an arc with respect to the connector post  32  and thereby adjust the valve&#39;s position for dimensional irregularities between the valve openings and the bolt holes in the manifold. When the bolts are fully tightened, the tabs  28  on electrohydraulic valves  21 – 23  are clamped between the base plate  12  and the manifold  25  preventing further movement of the valves, which thereby are secured in place. 
     Furthermore, vibration produced by engine operation is absorbed by the lead frame  30  flexing along is length and is not concentrated at the electrical connections between the valves and the lead frame. This distribution of the vibrational motion significantly reduces fatigue which otherwise would occur at these joints. 
     The foregoing description was primarily directed to a preferred embodiments of the present invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.