Abstract:
The invention is a valve deactivator assembly ( 15 ) for use in connection with a valve train of an internal combustion engine. In application, a pre-selected number of the engine cylinders would each be equipped with a deactivator connected to its intake engine valve. Upon driver selection or predetermined road conditions, sufficient lost motion would be introduced into the valve train so that the valve would remain closed and the cylinder deactivated as the engine is in operation. The deactivator has in its inner body ( 19 ) a latch assembly that is in a latched condition for normal operation of the valve train. When it is desired to retain the valve in the closed position and deactivate a cylinder, the latch assembly is caused to be moved to the unlatched condition by increase in the pressure of the engine oil. When the latch assembly is unlatched, significant lost motion is introduced into the valve train causing the valve to remain closed and the cylinder is deactivated.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part (CIP) of co-pending application U.S. Ser. No. 09/533,832, filed Mar. 23, 2000, in the name of Kynan L. Church, Austin R. Zurface and Keith Hampton for a “Hydraulically Actuated Latching Pin Valve Deactivation”, which application is a continuation-in-part (CIP) of co-pending application U.S. Ser. No. 09/255,366, filed Feb. 23,1999, in the name of Kynan L. Church for a “Hydraulically Actuated Valve Deactivating Roller Follower”, now U.S. Pat. No. 6,196,175 issued Mar. 6, 2001. 
     
    
     
       BACKGROUND OF THE DISCLOSURE  
         [0002]    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, and even more particularly, to such a valve deactivator of the type utilizing a latching pin arrangement.  
           [0003]    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 the normal opening and closing, the invention is especially suited for introducing into the valve train sufficient lash (also referred to hereinafter as “lost motion”), such that the valves no longer open and close at all, and the invention will be described in connection therewith.  
           [0004]    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 gear train. In such a gear train, 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. At the same time, the fulcrum permits the rocker arm to engage in cyclical, pivotal movement, in response to the cyclical movement of the push rod, which results in the engagement of the push rod with the lobes of a rotating cam shaft.  
           [0005]    There are a number of known valve deactivator assemblies which are operably associated with the fulcrum portion of the rocker arm in a push rod type valve gear train. Such known valve deactivator assemblies, when in the latched condition, restrain the fulcrum portion of the rocker arm to cause the rocker arm to move in its normal cyclical, pivotal movement. However, in an unlatched condition, the valve deactivator assembly permits the fulcrum portion of the rocker arm to engage in “lost motion” such that the cyclical, pivotal movement of the push rod causes the rocker arm to undergo cyclical, pivotal movement about the end which is in engagement with the engine poppet valve. In other words, the rocker arm merely pivots, but the engine poppet valve does not move, and hence, is in its deactivated condition.  
           [0006]    A different approach to valve deactivation in a push rod type valve gear train is illustrated and described in above-cited U.S. Pat. No. 6,196,175. In the cited patent, the valve deactivation is accomplished in a roller follower of a type having an outer body which moves with the roller follower, and an inner body which imparts motion to the push rod. The valve deactivator has either an unlatched condition, in which lost motion occurs, or a latched condition, in which the inner and outer bodies are latched to each other and motion imparted to the roller follower by the cam is, in turn, transmitted to the push rod to provide normal valve opening and closing.  
           [0007]    A generally similar type of valve deactivator is illustrated and described in U.S. Pat. No. 5,655,487, for use in an overhead cam (“OHC”) engine, of the type utilizing an end pivot rocker arm. In a valve gear train of the type described above, the pivot point for the end of the rocker arm is a hydraulic lash adjuster (“HLA”), with the opposite end of the rocker arm being in engagement with the engine poppet valve.  
           [0008]    In the valve deactivator of the above-cited patent, the latching arrangement between the inner and outer bodies is configured such that the inner body must be maintained in a predetermined rotational orientation within the outer body, in order for proper latching and unlatching to occur. Such a need for maintaining rotational orientation of the inner body member, relative to the outer body member, adds substantially to the overall complexity and cost of both the manufacture and assembly of the valve deactivating HLA. In connection with the development of the present invention, it has also been determined that another disadvantage of the valve deactivator of the cited patent is that, when the latching mechanism is latched, all of the gear train force being supported by the latching mechanism is being carried over a relatively small area, thus resulting in higher than desirable surface stresses in the latch mechanism.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    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.  
           [0010]    It is a more specific object of the present invention to provide an improved valve deactivator assembly wherein the inner body member does not need to be in any particular rotational orientation relative to the outer body member, in order for proper latching and unlatching to occur.  
           [0011]    It is a related object of the present invention to provide an improved valve deactivating HLA for use in OHC valve gear train of the end pivot rocker arm type, in which the HLA is reasonably compact, to minimize the need for overall re-design of the valve gear train.  
           [0012]    It is a further object of the present invention to provide an improved latching mechanism which is useable in either a valve deactivating HLA for use in OHC valve gear train of the end pivot rocker arm type, or in a valve deactivating roller follower for use in a push rod type valve gear train.  
           [0013]    The above and other objects of the invention are accomplished by the provision of an improved valve deactivator assembly for an internal combustion engine of the type having valve means for controlling the flow to and from a combustion chamber, drive means for providing cyclical motion for opening and closing the valve means in timed relationship to the events in the combustion chamber, and valve gear means operative in response to the cyclical motion to effect cyclical opening and closing of the valve means. The valve deactivator assembly comprises part of the valve gear means and includes an outer body member and an inner body member disposed within the outer body member and being reciprocable relative thereto, and a spring biasing the inner body member toward an axially extended position relative to the outer body member. A latch assembly is wholly disposed within the inner body member when the outer and inner body members are in an unlatched condition, the latch assembly including a radially moveable latch member and spring means biasing the latch member toward a latched condition. A source of pressurized fluid is operably associated with the latch assembly and is operable to bias the latch member toward the unlatched condition.  
           [0014]    The improved valve deactivator assembly is characterized by the latch assembly further comprising the outer body member defining a generally annular, internal groove including an annular latch surface and at least one fluid port disposed in open fluid communication with the annular internal groove and in fluid communication with the source of pressurized fluid. The latch member defines a generally planar stop surface oriented generally parallel to the annular latch surface and disposed for face-to-face engagement therewith when the latch member is in the latched condition, whereby the inner body member may be in any rotational orientation relative to the outer body member. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a fragmentary, axial cross-section taken through a vehicle internal combustion engine, illustrating a typical valve gear train of the type with which the present invention may be utilized.  
         [0016]    [0016]FIG. 2 is a greatly enlarged, axial cross-section illustrating the valve deactivator assembly of the present invention in its unlatched condition.  
         [0017]    [0017]FIG. 3 is a further enlarged, fragmentary, axial cross-section of a portion of the valve deactivator assembly of the present invention in its latched condition.  
         [0018]    [0018]FIG. 4 is a transverse cross-section, taken on line  4 - 4  of FIG. 3, but with the latching elements retracted, illustrating one important aspect of the present invention.  
         [0019]    [0019]FIG. 5 is a view taken on line  5 - 5  of FIG. 4.  
         [0020]    [0020]FIG. 6 is an enlarged, axial cross-section illustrating the latching mechanism of the present invention utilized in a deactivating roller follower.  
         [0021]    [0021]FIG. 7 is a somewhat enlarged, perspective view of the body member of the embodiment of FIG. 6.  
         [0022]    [0022]FIG. 8 is a plan view of the wire ring orientation member which comprises one aspect of the alternative embodiment of FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    Referring now to the drawings, which are not intended to limit the invention, there is illustrated, by way of example only, an OHC valve gear train of the type which may utilize the valve deactivator assembly of the present invention. In FIG. 1, there is shown fragmentarily a cylinder head  11  of an internal combustion engine. The cylinder head  11  defines a generally cylindrical bore  13  within which is disposed a valve deactivator assembly, generally designated  15 .  
         [0024]    The valve deactivator assembly  15  includes an outer body member  17 , an inner body member  19 , and a plunger element (to be described subsequently) which includes a ball plunger portion  21 . As is well known to those skilled in the art, the cylinder head  11  also defines an engine oil passage  23  which intersects the bore  13 , and by means of which pressurized oil is communicated to the valve deactivator assembly  15 , as will be described in greater detail subsequently.  
         [0025]    Referring still primarily to FIG. 1, the ball plunger portion  21  is received within a hemispherical socket  25  of a rocker arm  27 . At the end of the rocker arm  27  opposite the socket  25  is a valve contacting pad  29 , the underside of which is in engagement with the tip  31  of an engine poppet valve  33  (of which only the upper portion of the stem is shown). The rocker arm  27  includes a rotatable cam follower  35 , which is in engagement with the surface of a valve actuating cam  37 .  
         [0026]    Typically, but by way of example only, the present invention would be utilized with an eight cylinder engine for which the valve gear train would include eight pairs of intake and exhaust valve rocker arms, with four of the eight being equipped with the valve deactivator assembly  15  of the present invention. In other words, four of the eight cylinders could be selectively deactivated by introducing sufficient lost motion into the valve drive train for that particular valve, so that the cyclical motion of the cam  37  does not result in any corresponding cyclical opening and closing movement of the poppet valve  33  (i.e., of either the intake valve or the exhaust valve for that particular cylinder). Under the “deactivated” condition described, the engine poppet valve  33  remains closed under the influence of a valve closing spring (not shown herein). It would also be typical that, for the four cylinders which cannot be selectively deactivated, the socket  25  of the rocker arm  27  would engage the ball plunger portion of a “conventional” hydraulic lash adjuster, i.e., an HLA not having valve deactivation capability.  
         [0027]    When the lobe of the cam  37  engages the follower  35  (as shown in FIG. 1), under normal operating conditions, the ball plunger portion  21  would comprise the pivot point for the rocker arm  27 , such that the rocker arm would pivot about the ball plunger portion  21  as the follower  35  is engaged by the cam lobe  37 , thus forcing the engine poppet valve  33  in a downward direction.  
         [0028]    Referring now primarily to FIG. 2, those skilled in the art should understand that the invention is not limited to any particular valve deactivator or HLA configuration, except as is noted hereinafter in the appended claims. Thus, the present invention is being illustrated and described in connection with a valve deactivating HLA for use with an end pivot rocker arm, but the invention could also be utilized in, for example, a valve deactivating roller follower for a push rod type gear train, as will be described in connection with the alternative embodiment shown in FIGS. 6 through 8.  
         [0029]    In FIG. 2, the valve deactivator assembly  15  is shown in its unlatched condition, with the inner body member  19  and ball plunger portion  21  fully “retracted”, i.e., moved as far downward as possible within the outer body member  17 . Disposed in engagement with an internal groove formed in the outer body member  17  is a stop clip  39  which serves as the lower spring seat for a lost motion compression spring  41 . At its upper end, the spring  41  is seated against a pilot ring  43 , which is preferably fixed to move with the upper end of the inner body member  19  by any suitable means, such as a wire snap ring  45 . Thus, the compression spring  41  biases the inner body member  19  and the ball plunger portion  21  “upward” in FIG. 2, toward a fully extended condition (the condition shown in FIG. 3), in the absence of a downward force being exerted on the ball plunger  21  by the socket  25  of the rocker arm  27 , when the lobe of the cam  37  is in the position shown in FIG. 1.  
         [0030]    Referring still primarily to FIG. 2, the ball plunger portion  21  is formed at the upper end of a generally cylindrical plunger element  47  which is retained for limited reciprocal movement within the inner body member  19  by means of a wire snap ring  49 . The inner body member  19  defines a stepped bore  51  which serves as the high pressure chamber for a hydraulic lash compensation element, generally designated  53 , which may be of a type well known to those skilled in the art, is not an essential feature of the invention, and will not be described further herein. Disposed within the plunger element  47  is a fluid reservoir  55 , which is in fluid communication with the high pressure chamber  51  by means of the lash compensation element  53 , in a manner well known to those skilled in the art.  
         [0031]    Disposed between the outer body member  17  and the inner body member  19  is a generally cylindrical chamber  57 , in which the compression spring  41  is disposed. The chamber  57  would typically be filled with engine lubricating oil, some of which would enter through a port  59  formed in the wall of the outer body member  17 .  
         [0032]    The lower portion of the inner body member  19  defines a pair of diametrically arranged bores  61  which, by way of example only, are illustrated herein as being generally cylindrical, but may be of a variety of configurations. Disposed within each bore  61  is a latching element  63 , and in the subject embodiment, the latching members  63  are identical, and thus may be interchangeable. Preferably, the latching elements  63  are hollow to receive therein a single compression spring  65 . With the bores  61  arranged diametrically, a single spring  65  is sufficient to bias both latching elements  63  radially outward toward a latched condition (as shown in FIG. 3).  
         [0033]    Referring now to FIGS. 2 and 3 together, the outer body member  17  defines, by way of example only, a pair of ports  67 , at least one of which is in communication with the engine oil passage  23  (see FIG. 1). The ports  67  open into an annular, internal groove  69 , the groove  69  forming an annular latch surface  71  (see FIG. 4). Each of the latching elements  63  includes a latch portion  73 , each of which is generally half-circular (see FIG. 5), and each of which includes on its underside, a generally flat, planar stop surface  75 . Each latch portion  73  includes a radially outer end surface  77 , which in the subject embodiment, has about the same radius of curvature as the adjacent annular, internal groove  69 .  
         [0034]    Those skilled in the art will understand that the ports  59  are in communication with a relatively constant source of preferably low pressure lubrication oil, whereas the ports  67  are in communication with a separate fluid source. The fluid source with which the ports  67  are in communication is a source of a control fluid pressure which can be controlled between a relatively low pressure (FIG. 3) and a relatively higher pressure (FIG. 2).  
         [0035]    Referring now primarily to FIG. 4, each latching element  63  defines a flat  79 , which is preferably perpendicular to the planar stop surface  75 . Adjacent each flat  79 , the inner body member  19  defines a vertical bore  80 , and into each bore  80 , after the latching elements  63  are in place in the bores  61 , a pin  81  is pressed in and is disposed closely spaced apart from the flat  79 , as shown in FIG. 4. The pins  81  serve two primary functions, one of which is to retain the latching elements  63  within the bores  61  as the inner body member  19  is handled during assembly of the entire deactivator assembly  15 . The other function is to maintain the rotational orientation of each latching element  63  within its bore  61 , as shown in FIG. 5, so that both of the planar stop surfaces  75  will always remain substantially parallel to the annular latch surface  71 .  
         [0036]    As a result of the above-described parallel relationship of the surfaces  71  and  75 , the inner body member  19  can have any rotational orientation within the outer body member  17 , and proper latching will still occur, which is one important aspect of the present invention. In other words, although in FIG. 4 the latch portion  73  is shown as disposed adjacent the ports  67 , such is not necessary, and the inner body member  19  could be inserted within the outer body member  17  at any relative rotational orientation. Another result of the parallel relationship of the surfaces  71  and  75  is that any forces exerted on the deactivator assembly  15  are taken up by the face-to-face engagement of the two planar stop surfaces  75  and the annular latch surface  71 , rather than by a cylindrical member within a circular opening (line-to-line contact) as was known in the prior art.  
         [0037]    When it is desired to deactivate the engine poppet valve  33  from the latched condition shown in FIG. 3, an appropriate signal is transmitted to the engine oil pressure system, increasing the oil pressure in the engine oil passage  23 . The increased oil pressure is communicated through one of the ports  67 , filling the annular, internal groove  69  with pressurized fluid. The pressurized fluid contacts the end surfaces  77  of the latch portions  73 , biasing the latching elements  63  from the latched condition shown in FIG. 3 toward an unlatched condition as shown in FIG. 4, with the stop surfaces  75  retracted and out of engagement with the annular latch surface  71 . With the latching elements  63  in their unlatched condition, the inner body member  19  may be moved by external forces (as explained previously) from its fully extended position as shown in FIG. 3 to its fully retracted position as shown in FIG. 2, thus introducing lost motion into the valve gear train.  
         [0038]    As is typical in the valve deactivator art, mode transitions, either from the latched condition to the unlatched condition, or vice versa, occur only when the cam  37  is on the base circle portion. As is well known to those skilled in the art, mode transitions are accomplished only on base circle in order that the mode change occurs while the valve deactivator assembly  15 , and more specifically, the latching mechanism, is not under load. For example, in FIG. 3, even though the valve deactivator assembly  15  is in the latched condition, when the cam  37  has its base circle portion engaging the follower  35 , the latching elements  63  can easily be slid from the latched condition shown to the unlatched condition. However, after the cam  37  rotates to the position shown in FIG. 1, there is sufficient downward force on the ball plunger  21 , and thus on the inner body member  19 , such that the frictional engagement force between the annular latch surface  71  and the stop surfaces  75  would be enough such that the latching elements  63  could not be biased radially inward to their unlatched positions, except perhaps with substantially higher fluid pressure. Those skilled in the art will understand that such fluid pressures of the type which would be required are generally not available and would probably not be desirable.  
         [0039]    Referring now primarily to FIGS. 6 through 8, there is illustrated an alternative embodiment of the invention in which elements which are the same or very similar to those in the primary embodiment bear the same reference numeral, plus “100”, and new elements bear reference numerals in excess of “180”. Thus, the embodiment shown in FIG. 6 is a deactivating roller follower assembly, generally designated  115  including an outer body member  117 , an inner body member  119  (see also FIG. 7) and a plunger element  121 . Mounted for rotation relative to the lower end of the outer body member  117  is a roller member  181  which, as is well know to those skilled in the art, engages the cam profile on the cam shaft. There are two purposes for illustrating the alternative embodiment of FIGS. 6 through 8. The first is to show the latching mechanism of the present invention in a different type of deactivator assembly (i.e., FIGS. 6 through 8 relate to a push rod type valve gear train). Secondly, the alternative embodiment illustrates a different arrangement for orienting the latching elements  163  within the bores  161 , so that the planar stop surfaces will always remain substantially parallel to the annular latch surface, as was described in connection with the primary embodiment.  
         [0040]    Referring now primarily to FIGS. 7 and 8, it may be seen that the inner body member  119  includes a relatively larger diameter portion  183  which defines, toward its lower end (right end in FIGS. 6 and 7) an annular groove  185 . The annular groove intersects both of the diametrically arranged bores  161 . Received within the annular groove  185  is a wire ring orientation member  187  which is shown in FIG. 8, but which may take any one of a number of shapes and configurations, within the scope of the present invention. What is important about the orientation member  187  is that it extends across each of the bores  161  in such a way that the planar stop surfaces  175  defined by the latching elements  163  engage the orientation member  187 . As a result, any rotation of the latching members  163  within the bores  161  will be prevented, and the proper rotational orientation of the latching members  163  will be insured and yet, the orientation member  187  may be removed quickly and easily for purposes of service or repair, in a non-destructive manner.  
         [0041]    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.