Abstract:
A valve deactivator assembly ( 49   a ) for an internal combustion engine of the type having valve means ( 29 ), drive means ( 13 ) for providing cyclical motion for opening and closing the valve means ( 29 ) in timed relationship to the events in a combustion chamber ( 30 ), and valve gear ( 21,23 ) operative in response to the cyclical motion to effect cyclical opening and closing of the valves ( 29 ). The valve deactivator assembly ( 49   a ) comprises part of the valve gear ( 21,23 ) and is disposed in series relationship between the drive means ( 13 ) and said valves ( 29 ). The valve deactivator assembly ( 49   a ) includes an outer body member ( 53 ) disposed for engagement with the drive means ( 13 ) and for cyclical motion therewith. There is an inner body member ( 61 ) disposed within the outer body member ( 53 ) and reciprocable relative thereto, the inner body member ( 61 ) having an upper end portion ( 93 ) disposed external to the outer body member ( 53 ) when the members ( 53,61 ) are in a latched condition. A movable latch member ( 97 ) is operably associated with the upper end portion ( 93 ) of the inner body member ( 61 ), the latch member ( 97 ) being movable between a latched condition (FIG.  1 ), operable to transmit the cyclic motion, and an unlatched condition (FIG.  2 ), operable to permit lost motion between the drive means ( 13 ) and the valve means ( 29 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     MICROFICHE APPENDIX 
     Not Applicable 
     BACKGROUND OF THE DISCLOSURE 
     The present invention relates to an improved valve train for an internal combustion engine, and more particularly, to a valve deactivator assembly for use therein. 
     Although the valve deactivator assembly of the present invention may be utilized to introduce some additional lash into the valve train, such that the valves open and close by an amount less than normal, the invention is especially suited for introducing into the valve train sufficient lash (also referred hereinafter as “lost motion”), such that the valves no longer open and close at all, and the invention will be described in connection therewith. 
     Valve deactivators of the general type to which the invention relates are known, especially in connection with internal combustion engines having push rod type valve train in which there is a rocker arm, with one end of the rocker arm engaging a push rod, and the other end engaging the engine poppet valve. Typically, a central portion of the rocker arm is fixed relative to the cylinder head (or other suitable structure) by a fulcrum arrangement, as is well known to those skilled in the art, in which the fulcrum normally prevents movement of the central portion of the rocker arm in an “up and down” direction, while permitting the rocker arm to engage in cyclical, pivotal movement, in response to the cyclical motion of the push rod, which results from the engagement of the push rod with the lobes of the rotating camshaft. 
     Examples of known valve deactivator assemblies are shown and described in U.S. Pat. Nos. 4,221,199; 4,256,070; 4,305,356; and 4,380,219, all of which are assigned to the assignee of the present invention, and incorporated herein by reference. The valve deactivators of the above incorporated patents have typically involved some sort of latch member which is movable (typically, rotatable, but in some cases, movable linearly) between a latched position and an unlatched position. The movement of the latch member conventionally occurs is response to linear movement of a linear actuator, by means of an appropriate linkage arrangement. 
     Although the prior art valve deactivators have operated in a generally satisfactory manner, the actuator arrangement, including the required linkage, has resulted in an unacceptably slow response time, thus limiting the ability of the arrangement to be operated by the engine microprocessor, in synchronism with various other engine systems. The prior art devices typically had a response time, from “ON” to “OFF”, or vice versa, in the range of about 100 to 200 milliseconds 
     In modern internal combustion engines, utilizing fuel injection, it is especially desirable in a valve deactivator system to turn off the fuel injectors at the same time that the operation of the valves is stopped. However, the fuel injectors are electrically actuated, and can be turned off almost instantaneously, and therefore, it is desirable to be able to activate the valves and turn on the fuel injectors, or deactivate the valves and turn off the fuel injectors, within the ensuing, single revolution of the engine camshaft. Thus, and by way of example only, in developing the present invention, the goal for the valve deactivator system was a maximum time of less than 25 milliseconds from “ON” to “OFF”, or vice versa. 
     The actuator and linkage arrangements used in the prior art devices have resulted in an excessive number of parts, increasing the overall cost of the system. Finally, the actuator and linkage arrangements have typically taken up enough space to limit the packaging options in the engine cylinder head. This has been especially true in the valve deactivator arrangements of the type shown in the above-incorporated patents wherein the deactivator mechanism comprises part of the fulcrum arrangement of the rocker arm. In a conventional “center-pivot” rocker arm for use with a push rod arrangement, the fulcrum arrangement would typically be disposed entirely within the profile of the rocker arm. However, adding a valve deactivator mechanism to the fulcrum arrangement would cause the fulcrum arrangement to extend substantially above the profile of the rocker arm, thus substantially altering the overall configuration of the cylinder head. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an improved valve deactivator assembly which overcomes the above-described disadvantages of the prior art. 
     It is a more specific object of the present invention to provide an improved valve deactivator assembly, especially suited for push rod type valve gear, wherein the valve deactivator does not comprise part of the fulcrum arrangement for the rocker arm, which would substantially increase the overall size of the fulcrum arrangement. 
     It is a related object of the present invention to provide an improved valve deactivator system wherein the valve deactivator mechanism comprises part of an hydraulic roller follower, which is in engagement with the cam profile. 
     The above and other objects of the invention are accomplished by the provision of a valve deactivator assembly for an internal combustion engine of the type having valve means for controlling the flow to and from a combustion chamber and drive means for providing cyclical motion for opening and closing the valve means in timed relationship to the events in the combustion chamber. Valve gear means is operative in response to the cyclic motion to effect cyclic opening and closing of the valve means. The valve deactivator assembly comprises part of the valve gear means and is disposed in series relationship between the drive means and the valve means. 
     The valve deactivator assembly is characterized by an outer body member disposed for engagement with the drive means and for cyclical motion therewith. An inner body member is disposed within the outer body member and reciprocable relative thereto, the inner body member having an upper end portion disposed external to the outer body member when the members are in a latched condition. A moveable latch member is operably associated with the upper end portion of the inner body member, the latch member being moveable between a latched condition operable to transmit the cyclic motion, and an unlatched condition, operable to permit lost motion between the drive means and the valve means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary, axial cross-section taken through the cylinder head of a vehicle internal combustion engine, illustrating the valve deactivator mechanism of the present invention in external plan view. 
     FIG. 2 is a somewhat enlarged, top plan view showing only the valve deactivator mechanism of the present invention. 
     FIG. 3 is an enlarged, fragmentary, transverse cross-section, taken generally on line  3 — 3  of FIG. 2, but showing only a single valve deactivator for ease of illustration. 
     FIG. 4 is a transverse cross-section taken on line  4 — 4  of FIG. 2, and on the same scale as FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, which are not intended to limit the invention, FIG. 1 illustrates a valve actuating drive train of the push rod type, although it should be understood that the use of the present invention is not so limited. FIG. 1 illustrates a cylinder head  11  on which are mounted a drive assembly  13 , a rocker arm assembly  15 , and an engine poppet valve assembly, generally designated  17 . 
     The drive assembly  13  includes a camshaft  18  having a cam  19 , a hydraulic roller follower  21 , and a push rod  23  (shown “broken” for ease of illustration). The cam  19  includes a lift portion  25  and a dwell (base circle) portion  27 . The poppet valve assembly  17  includes a poppet valve  29 , operable to control flow to and from a combustion chamber  30 , and a spring  31  which biases the poppet valve  29  toward the closed position shown in FIG. 1, as is well known to those skilled in the art. 
     The rocker arm assembly  15  includes a rocker arm  33  of the center-pivot type, the rocker arm  33  including one end  35  which is adapted to receive cyclic input motion from the push rod  23 , and another end  37  which is adapted to transmit to the valve  29  the cyclic motion of the push rod  23 . As a result, the engine poppet valve  29  has a cyclic opening and closing motion, corresponding to that of the push rod  23 , all of which is well known to those skilled in the art. In the subject embodiment, the only motion of the rocker arm  33  is its pivotal movement, with the ends  35  and  37  engaging in alternating up and down movement. 
     The rocker arm  33  includes a pivot portion  39 , disposed intermediate the ends  35  and  37 , and a fulcrum  41  is disposed within the pivot portion  39  in a manner which permits the rocker arm  33  to pivot as described previously. The fulcrum  41  has a threaded mounting bolt  43  extending therethrough and being in threaded engagement with an internally threaded bore  45  defined by the cylinder head  11 . 
     Typically, the present invention would be utilized with an eight cylinder engine, for which the valve drive train would include four pairs of intake and exhaust valve rocker arms, each equipped with a valve deactivator assembly, generally designated  47 . In other words, four of the eight cylinders can be selectively deactivated by introducing sufficient “lost motion” into the valve drive train for that particular valve, so that the cyclic motion of the push rod  23  does not result in any corresponding cyclic opening and closing movement of the poppet valve  29  (i.e., of either the intake valve or exhaust valve for that particular cylinder). More specifically, the lost motion is introduced into the drive train at the hydraulic roller follower  21 , which, in the subject embodiment, actually comprises part of the valve deactivator assembly  47 , as will be described further subsequently. Although not an essential feature of the invention, it is preferred that the valve deactivator assembly  47  operate by permitting lost motion between the cam  19  and the rocker arm  33 , such that cyclic motion of the push rod  23  does not result in any pivotal movement of the rocker arm about its pivot portion  39 . 
     In accordance with one important aspect of the present invention, the preferred embodiment of the valve deactivator assembly  47  comprises an assembly of a pair of valve deactivators,  49   a  and  49   b , which are operatively associated with a pair of poppet valves  29  wherein, typically, and as discussed above, one of the valves would be an intake valve and the other would be an exhaust valve, such that both the intake and exhaust functions are “deactivated”. The valve deactivators  49   a  and  49   b  would typically be identical, such that only the deactivator  49   a  will be described hereinafter. 
     In connection with the further description of the present invention, those skilled in the art will understand that where spatial terms such as “above” and “below”, and terms of similar import, are used to specify general relationships between parts, they are not necessarily intended to indicate orientation of the parts within a vehicle engine. Referring now to FIG. 2, in conjunction with FIG. 1, the valve deactivator assembly  47  includes a generally triangular mounting plate  51 , which would typically be fixed relative to the cylinder head  11 . Fixed to the mounting plate  51  is an electromagnetic actuator  52  which will be described in greater detail subsequently. 
     Referring now primarily to FIG. 3, an individual valve deactivator  49   a  will be described, it being noted that the lower portion thereof was identified in FIG. 1 as comprising a hydraulic roller follower  21 . An example of a conventional hydraulic roller follower, not having valve deactivator capability, is illustrated and described in U.S. Pat. No. 4,607,599, assigned to the assignee of the present invention and incorporated herein by reference. The valve deactivator  49   a  includes an outer body member  53  which is disposed to reciprocate within a bore  55  (see FIG. 1) in the cylinder head  11 . The body member  53  is in contact with, and follows the cam  19  through a conventional roller follower  57 , shown herein as being of the needle roller bearing type. At the upper end of the outer body member  53  is a plurality of crenellations  59  of the type which are generally well known to those skilled in the art from the above-incorporated patents. The function of the crenallations  59  will be described in greater detail subsequently. 
     Disposed within the outer body member  53  is an inner body member  61 . Toward the lower end in FIG. 3 the inner body member  61  is surrounded by a stop clip  63  which serves as the lower spring seat for a lost motion compression spring  65 . At its upper end, the spring  65  is seated against another stop clip  67 , which engages a shoulder on the outer periphery of the inner body member  61 . Above the stop clip  67 , and disposed radially between the inner surface of the outer body member  53  and the outer surface of the inner body member  61  is a pilot ring  69 , having its upper end seated against a snap ring  71 . 
     Disposed within the inner body member  61  is a hydraulic lash compensation element, generally designated  73 , of the general type which is now well known to those skilled in the art, and which will not be described in great detail herein. The lash compensation element  73  includes a plunger member  75  defining a socket surface  77 , adapted for engagement with the push rod  23 , in a manner also well known to those skilled in the art. The lash compensation element  75  defines a fluid reservoir  79  which receives pressurized engine oil by means of a fluid port  81 , defined by the outer body member  53  being in fluid communication with an engine oil passage (not shown herein) formed in the cylinder head  11 . Such pressurized fluid fills a chamber  85  formed between the outer body member  53  and the inner body member  61 . From the chamber  85 , fluid flows through a fluid port  87  formed in the cylindrical wall of the inner body member  61 , then through a fluid port  89  formed in the lash compensation element  73 , then enters the fluid reservoir  79 . Disposed between a bottom end wall  90  of the inner body member  61  and the lash compensation element  73  is a high pressure chamber  91 , the function of which is to contain fluid under substantial pressure during a valve event, thus providing some rigidity within the valve gear train, but also providing the capability of compensating for lash as is well known to those skilled in the lash compensation art. 
     Referring now to FIG. 3, in conjunction with FIG. 2, the upper end of the inner body member  61  is enlarged and defines a shoulder surface  93 . Spaced axially below the surface  93  is a snap ring  95 , and disposed axially between the surface  93  and the snap ring  95  is an annular latch member  97 . As may best be seen in FIG. 2, the latch member  97  defines a plurality of arcuate openings  99 , there being four of the openings  99  uniformly spaced, circumferentially, in FIG.  2 . The latch member  97  also includes a pair of teeth  101 , the function of which will be described subsequently. As may best be seen in FIG. 2, in which the valve deactivator  49   a  is in its unlatched condition, the crenellations  59  are aligned, circumferentially, with the arcuate openings  99 . 
     Referring now primarily to FIG. 4, the electromagnetic actuator  52  includes a stepped, generally cylindrical support member  103 , which is preferably fixed relative to the mounting plate  51 . Surrounding the support member  103 , toward the upper end thereof, is an annular electromagnetic coil  105  which, in turn, is surrounded by an outer, stationary pole piece  107 . Disposed beneath the coil  105  is a rotatable armature  109 , and extending radially outward from the armature  109  is an actuating ring  111 . The actuating ring  111  includes a tooth  113  (seen only in FIG.  2 ), the tooth  113  being in engagement with the teeth  101  of the annular latch member  97 . Thus, when it is desired to operate the valve deactivators in the unlatched condition, an appropriate electrical signal is transmitted to the coil  105 , and the resulting electromagnetic field in the support member  103  and stationary pole piece  107  rotates the armature  109 , as well as the actuating ring  111 , which in turn rotates the latch member  97  toward its unlatched position shown in FIG. 2, from the latched position. 
     It should be noted that, preferably, the logic controlling the signal to the actuator  52  operates such that the change in condition, from latched to unlatched, or vice versa, occurs while the follower  57  is in contact with the base circle portion  27  of the cam  19 . As is well known to those skilled in the art, it would be difficult to change the condition of the valve deactivator  49   a  with the follower  57  on the lift portion  25  of the cam because of the additional loading to which the deactivator is subjected. Also, it is clearly more desirable to make any change in the condition of the deactivator before the start of the next “valve event”, as that term is understood. 
     In the unlatched condition shown in FIG. 2, in which the actuator  52  is energized, as the cam  19  rotates clockwise from the position shown in FIG. 1, such that the lift portion  25  engages the follower  57 , the result is upward movement of the roller follower  21  (i.e., upward movement of the outer body member  53 ). However, in the unlatched condition, with the crenellations  59  aligned with the openings  99 , the upward movement of the outer body member  53  merely results in the crenellations  59  projecting upward through the openings  99 . Thus, there is “lost motion” of the body member  53  in the sense that the body member  53  moves upward, but with no corresponding upward movement of the inner body member  61  occurring, and therefore, no corresponding upward movement of the lash compensation element  73  or of the push rod  23 . Although the upward movement of the outer body member  53  will exert an upward biasing force on the inner body member  61 , by means of the lost motion spring  65 , the biasing force of the poppet valve spring  31  is selected to be greater than that of the lost motion spring  65 , and no corresponding upward movement of the inner body member  61  occurs. As a result, the associated valve is deactivated when the valve deactivator  49   a  is unlatched. 
     It should be noted that, as the outer body member  53  moves upward in the unlatched condition, the pilot ring  69  moves upward with the member  53 , such that the volume of the chamber  85  doesn&#39;t change. As a result, there are no undesirable pressure pulses created, as would occur if the volume of the chamber  85  varied during reciprocation of the member  53 . Those skilled in the art will understand that any such undesired pressure pulses would possibly impact the proper operation of the other valve gear elements, such as the lash compensation elements associated with valves which are not then being deactivated. 
     When it is again desired to operate this set of valves  29  in the normal manner, instead of in the deactivated mode, the signal to the electromagnetic actuator  52  is discontinued, thus permitting the latch member  97  to rotate from the unlatched position shown in FIG. 2 toward the latched position, under the influence of a biasing (return) spring (not shown herein) in the actuator  52 . As the latch members  97  rotate to the latched position, they rotate about 20 to 25 degrees from the position shown in FIG. 2, such that each of the crenellations  59 , instead of being aligned with an opening  99 , is disposed between two adjacent openings  99 . It is important to understand that when the follower  57  is engaging the base circle portion  27 , the upper surface of each of the crenellations  59  is spaced slightly downward from the underside of the latch member  97 . As a result, there is no substantial resistance to rotation of the latch member  97  during a change in the condition of the valve deactivator, either to or from the latched condition. 
     As soon as the cam  19  rotates enough, the follower  57  leaves the base circle portion  27  and engages the lift portion  25 , biasing the outer body member  53  upward until the upper surfaces of the crenellations  59  engage the underside of the latch member  97 . Thereafter, up and down movement of the outer body member  53  results in corresponding up and down movement of both the inner body member  61  and the lash compensation element  75 , thus also moving the push rod  23  in its normal cyclical up and down motion to open and close the valve  29 . Therefore, FIGS. 1 and 4 could be considered to represent the latched condition of the deactivators  49   a  and  49   b , respectively. By way of example only, as the cam  19  rotates, the vertical movement of the deactivator  49   a  is about 8.5 mm, resulting in a vertical movement of the valve  29  of about 14 mm in going between closed (FIG. 1) and fully open. 
     As the valve deactivator  49   a  operates in its latched condition, and the inner body member moves up and down in FIGS. 1,  3 , and  4 , the latch member  97  moves up and down with the member  61 . However, the actuating ring  111  is fixed to the armature  109 , and has no movement in the vertical direction. Therefore, it is one important aspect of the present invention that the mesh of the teeth  101  and  113  permits upward and downward movement of the latch member  97 , relative to the actuating ring  111 , although it should be understood that the invention is not so limited, and various other means could be used to transmit rotational motion, while permitting relative vertical movement. 
     Although the subject embodiment of the invention includes a rotary type actuator  52 , it should be understood that such is not an essential feature of the invention, nor is the use of rotating latch members  97 . For example, either the actuator and/or the latch members could operate linearly, within the scope of the invention. However, the use herein of both the rotary latch member  97  and the rotary actuator  52  results in an optimum assembly in regard to the small size and the absence of complicated and expensive linkage members. Preferably, the electromagnetic actuator  52  could be made in accordance with the teachings of co-pending application U.S. Ser. No. 09/114,739, filed Jul. 13, 1998 in the name of Kynan L. Church for a “VALVE DEACTIVATOR FOR PEDESTAL TYPE ROCKER ARM”. 
     The invention has been described in great detail in the foregoing specification, and it is believed that various alterations and modifications of the invention will become apparent to those skilled in the art from a reading and understanding of the specification. It is intended that all such alterations and modifications are included in the invention, insofar as they come within the scope of the appended claims.