Patent Publication Number: US-10781725-B2

Title: Switchable rocker arm

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
     This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2017/077212, filed on Oct. 24, 2017, and claims benefit to British Patent Application No. GB 1703793.8, filed on Mar. 9, 2017. The International Application was published in English on Sep. 13, 2018 as WO/2018/162094 under PCT Article 21(2). 
     FIELD 
     The invention relates to a switchable rocker arm for a valve train assembly. 
     BACKGROUND 
     Internal combustion engines may comprise switchable engine or valve train components. For example, valve train assemblies may comprise a switchable rocker arm to provide for control of valve actuation (for example exhaust or inlet valve actuation and/or de-actuation) by alternating between at least two or more modes of operation (e.g. valve-lift modes). Such rocker arms typically involve multiple bodies, such as an inner arm and an outer arm. These bodies are latched together by a latching system comprising a movable latch pin to provide one mode of operation (e.g. a first valve-lift mode (e.g. normal engine combustion mode) and are unlatched, and hence can pivot with respect to each other, to provide a second mode of operation (e.g. a second valve-lift mode (e.g. valve de-activation mode). Typically, the moveable latch pin is used and actuated and de-actuated to switch between the two modes of operation. 
     SUMMARY 
     In an embodiment, the present invention provides a valve train assembly, comprising: at least one dual body rocker arm comprising a first body, a second body, a latching arrangement configured to latch and unlatch the first body and the second body, the latching arrangement comprising a latching pin that is biased to an unlatched configuration; and an actuator arrangement configured to control the latching arrangement, the actuator arrangement being configured to contact the latching arrangement to cause the latching pin to be moved into a latched configuration in which it latches the first and second bodies together, wherein, in use, movement of the rocker arm under action of a cam to cause a valve event moves the actuator arrangement out of contact with the latching arrangement while a contact force between the latching pin and one or other of the first and second bodies maintains the latching pin in the latched configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following: 
         FIGS. 1 to 3  illustrate sectional drawings of a first example of a dual body rocker arm, in different configurations; and 
         FIGS. 4 and 5  illustrate sectional drawings of a second example of a dual body rocker arm, in different configurations. 
     
    
    
     DETAILED DESCRIPTION 
     In an embodiment, the present invention provides a valve train assembly comprising at least one dual body rocker arm comprising a first body, a second body, a latching arrangement for latching and unlatching the first body and the second body and wherein the latching arrangement comprises a latching pin that is biased to an unlatched configuration, the assembly further comprising an actuator arrangement for controlling the latching arrangement and wherein the actuator arrangement is configured so that it contacts the latching arrangement to cause the latching pin to be moved into a latched configuration in which it latches the first and second bodies together and wherein, in use, movement of the rocker arm under the action of a cam to cause a valve event moves the actuator arrangement out of contact with the latching arrangement while a contact force between the latching pin and one or other of the first and second bodies maintains the latching pin in the latched configuration. 
     The first body may be an inner body of the dual body rocker arm, and the second body may be an outer body of the dual body rocker arm, and the contact force that maintains the latching pin in the latched configuration may be between the latching pin and the inner body. 
     The latching pin may be slidably supported in a bore defined by the outer body. 
     The latching pin may comprise a lip section extending from a portion of the latching pin and which may define a contact surface for contacting a contact surface of the inner body. 
     The cam may comprise a lift profile, and, in use, when the latching pin is in the latched configuration, engagement of the lift profile with the inner body may cause the inner body to press against the latching pin thereby to produce the contact force. 
     When the first and second bodies are latched together the first and second bodies may be arranged to pivot as a single body about a first pivot point under the action of the cam, which pivoting may move the latching arrangement out of contact with the actuator arrangement. 
     When the first and second bodies are unlatched the first and second bodies may be arranged to pivot with respect to one another under the action of the cam. 
     When the first and second bodies are latched together the dual body rocker arm may provide for a first mode of operation and when the first and second bodies are unlatched the dual body rocker arm may provide for a second mode of operation. 
     During an engine cycle, when the latching pin is in the latched configuration, there may be intermittent contact between the latching pin and the actuator arrangement. 
     The cam may comprise a base circle, and when the rocker arm is engaged with the base circle of the cam, and the actuator arrangement does not cause the latching pin to be moved into a latched configuration, the latching pin may move to the unlatched configuration. 
     The latching pin may be biased to the unlatched configuration by a return spring arranged around the latching pin. 
     The latching arrangement may further comprise a piston member and a compliance biasing uniut and the piston member may be arranged so that if the actuator arrangement attempts to cause the latch pin to move from the first unlatched configuration to the latched configuration at a time when the latch pin is prevented from being moved, the piston member may moves to bias the compliance biasing unit so that the compliance biasing unit urges the latch pin to the latched configuration when the latch pin again becomes moveable. 
     The piston member may be at least partially within the bore. 
     The piston member may comprise an aperture through which an end of the latch pin may extend whereby the piston member may be slidably mounted on the latch pin. 
     The actuator arrangement may comprise one or both of a piston actuator and a cam lobe supported on a shaft that is rotatable by an actuator. 
       FIGS. 1 to 3  illustrate a valve train assembly  100  comprising a dual body rocker arm  110  comprising an inner body  3  and an outer body  7  that are pivotably connected together at a pivot axis  9 . The rocker arm  110  further comprises at one end a latching arrangement  120  comprising a latch pin  1  slidably supported in a bore  28  in the outer body  7  and which can be urged between a first configuration (see  FIG. 3  for example) in which the latch pin  1  latches the outer body  7  and the inner body  3  together and a second configuration (see  FIG. 1  for example) in which the outer body  7  and the inner body  3  are un-latched. The latching arrangement  120  is located at a first end  110   a  of the rocker arm  110 . The first end  110   a  of the rocker arm  110  is opposite to a second end  110   b  of the rocker arm  110  at which the pivot axis  9  is located. 
     In the first configuration, the outer body  7  and the inner body  3  are latched together and hence can move or pivot about a pivot point, in this example a Hydraulic lash adjuster  11  as a single body so that the that rocker arm  1  provides a first primary function, for example, an engine valve  5  that it controls is activated as a result of the rocker arm  110  pivoting as a whole about the pivot point and exerting an opening force on the valve. 
     In the second configuration, the outer body  7  and the inner body  3  are un-latched so that the inner body  3 , for example, can pivot freely with respect to the outer body  7  so that rocker arm  110  provides a second secondary function, for example, the valve  5  it controls is de-activated (e.g. to provide cylinder de-activation) as a result of lost motion absorbed by the inner body  3  pivoting freely with respect to the outer body  7  and hence no opening force being applied to the valve  5 . 
     The outer body  7  comprises two generally parallel side walls  7   a  (only one is visible in  FIGS. 1 to 3 ) which define a space which contains the inner body  3 . The two side walls  7   a  are connected together at the first end  110   a  of the rocker arm  110 . 
     The inner body  3  is provided with an inner body cam follower  17 , in this example, a roller follower  17  rotatably mounted (for example with bearings) on an axle  19  for following an auxiliary cam profile of a cam shaft  4  and the outer body  7  is provided with a pair of cam followers (not visible in the figures), in this example, a pair of slider pads arranged either side of the roller follower  17  for following a pair of primary profiles of the cam  4 . The cam  4  is mounted on a cam shaft. 
     The rocker arm  110  further comprises a return spring arrangement for biasing the inner body  3  to its rest position after it is has pivoted with respect to the outer body  7 . 
     The outer body  7  is provided, at the first end  110   a  of the rocker arm  110 , with a recess  11   d  for receiving an end of the lash adjustor  11  so that the rocker arm  110  is mounted for pivotal movement about the lash adjustor  11 . The lash adjuster  11  which is supported in an engine block may, for example, be a hydraulic lash adjuster, and is used to accommodate slack (or lash) between components in the valve train assembly  100 . Lash adjusters are well known per se and so the lash adjuster  11  will not be described in any detail. 
     The latching arrangement  120  comprises the latch or latching pin  1 . The latch pin  1  is generally elongate and is located in the bore or channel  28  formed in the outer body  7  at the first end  110   a  of the rocker arm  110 . The bore  28  is a stepped bore and comprises a first section  28   a  and a second section  28   b . The first section  28   a  has an open end at the first end  110   a  of the rocker  110  and the second section  28   b  has an open end that faces the inner body  3 . The width (e.g. diameter) of the first section  28   a  is greater than the width of the second section  28   b.    
     The latch pin  1  comprises a first end portion  1   a  and a second end portion  1   b . The first end portion  1   a  is received in the first section  28   a  of the bore  28 , and extends out from the outer body  7  for contact with an actuator arrangement  2 . The second end portion  1   b  faces the inner body  3  and comprises a lip section  1   c  that extends from the second end portion  1   b  and defines a latch pin contact surface  1   d . The second end portion  1   b  is received in the second section  28   b  of the bore  28 . 
     The latch arrangement  120  further comprises a first spring  6  on an inner section of the latch pin  1  that is arranged to bias the latch pin  1  away from the latched configuration. The first or return spring  6  is a coil spring  6  received in the first section  28   a  of the stepped bore  28 , and arranged around the second end portion  1   b  of the latch pin  1 . A first end of the spring  6  abuts the first end portion  1   a  of the latch pin  1 , and a second end of the spring  6  abuts the outer body  7 . The spring  6  is arranged to bias the latch pin  1  out away from the inner body  3 , towards the second (unlatched) configuration. 
     During engine operation when the rocker arm  110  is in the first configuration (i.e. where the inner body  3  and the outer body  9  are latched together by the latching arrangement  120 , see e.g.  FIG. 2 ), as the cam shaft  4  rotates, a lift profile  4   a  of the cam shaft  4  engages the roller follower  17  exerting a force that causes the rocker arm  110  to pivot about the lash adjuster  11  to lift the valve  5  (i.e. move it downwards in the sense of the page) against the force of a valve return spring thus opening the valve  5 . As the peak of the lift profile  4   a  passes out of engagement with the roller follower  17  the valve return spring begins to close the valve  5  (i.e. the valve  5  is moved upwards in the sense of the page) and the rocker arm  3  pivots about the lash adjuster  7  in the opposite sense to when the valve  5  is opening. When a base circle  4   b  of the cam  4  engages the roller follower  17  the valve  5  is fully closed and the valve lift event is complete. 
     During engine operation when the rocker arm  110  is in the second configuration (i.e. where the inner body  3  and the outer body  7  are not latched together, see e.g.  FIG. 1 ) as the cam shaft  4  rotates, the lift profile  4   a  of the cam  4  engages the roller follower  17  exerting a force that causes the inner body  3  to pivot relative to the outer body  7  about the shaft  9  from a first orientation that the inner body  3  adopts when the base circle  4   b  engages the roller follower  17  to a second orientation that the inner body  3  adopts when the peak of the lift profile  4   a  engages the roller follower  17 . This movement of the inner body  3  ‘absorbs’ as ‘lost motion’ the motion that would otherwise be transmitted from the cam  4  to the valve  5  and hence the valve  5  remains closed. As the peak of the of the lift profile  4   a  passes out of engagement with the roller follower  17  and subsequently the base circle  4   b  engages the roller follower  17  again, the inner body  3  is urged by the lost motion return spring arrangement from the second orientation back to the first orientation. 
     The valve train assembly  100  further comprises an actuator arrangement or actuator  2  for operating the latch arrangement  120 . The actuator  2  is arranged to actuate the latching arrangement  120  from a position in which the latch pin  1  does not latch the inner body  3  and the outer body  7  together (i.e. such that the rocker arm  110  is in the second configuration), to a position in which the latch pin  1  latches the inner body  3  and the outer body  7  together (i.e. such that the rocker arm  110  is in the first configuration). The actuator  2  may be external to the rocker arm  110  and may take any suitable form including a piston type arrangement illustrated in  FIGS. 1 to 3 . The actuator  2  illustrated in  FIGS. 1 to 3  comprises a housing  40  defining a bore  41  in which is slidably received an actuating member  42 . The actuator  2  may be activated, for example by an engine management system, to cause the actuating member  42  to extend out of the housing  40  to actuate the latch pin  1  (as per  FIG. 2 ), and may be de-activated so as to cause the actuating member  42  to retract into the housing  40  thereby to not actuate the latch pin  1  (as per  FIG. 1 ). The actuator  2  may cause the actuating member  41  to move relative to the housing  40 , for example by electromagnetic means and/or hydraulic means. 
     As illustrated in  FIG. 1 , in a steady state condition the rocker arm  110  engages a base circle  4   b  of the cam  4 , the actuator  2  is de-activated, the return spring  6  is extended and the inner body  3  and outer body  7  are unlatched. 
     As illustrated in  FIG. 2 , in a condition in which the rocker arm  110  engages a base circle  4   b  of the cam  4  and the valve  5  is closed, the actuator  2  is activated, for example by an engine management system, and forces (see arrow in  FIG. 2 ) the latch pin  1  against the bias of the spring  6  to engage the inner body  3  so that the inner body  3  and the outer body  7  become latched and the spring  6  compressed. 
     As illustrated in  FIG. 3  the inner body  3  and the outer body  7  are latched together by the latch pin  1 , the rocker arm  110  engages the lift profile  4   a  of the cam  4  which cause the rocker arm  110  to pivot about the HLA  11  to cause a valve lift to open the valve  5 . The movement of the rocker arm  110  causes the actuator  2  to lose contact with the latch arrangement  120 . See e.g. area  33  of  FIG. 3 . 
     Advantageously, as best illustrated in  FIG. 3 , in this condition, the frictional force generated by the contact between inner body  3  and the latch pin  1  is sufficient to overcome the return force of the spring  6  so that the inner body  3  and the outer body  7  remain latched. 
     Specifically, in this configuration (see e.g.  FIG. 3 ) the lift-profile  4   a  of the cam  4  exerts a force (downwards in the sense of  FIG. 3 ) onto the roller follower  17  of the inner body  3  of the rocker arm  110 , against the valve spring of the valve  5 . This force causes a contact surface  3   a  of the inner body  3  to press hard against the latch pin contact surface  1   d  of the lip section  1   c  of the latch pin  1 . This causes increased friction between the latch pin contact surface  1   d  and a contact surface  3   a  of the inner body  3 . The increased friction is larger than the force exerted by the spring  6  on the latch pin  1  to bias the latch pin  1  to the unlatched configuration. Hence, with the lift profile  4   a  engaging the follower  17  of the inner body  3  of the rocker arm  1 , the latch pin  1  does not move from the latched position, and hence the inner body  3  and the outer body  7  remains latched. This is despite the actuator  2  not being in contact with the latch pin  1  during this portion of the engine cycle. 
     Once the base circle  4   b  of the cam  4  returns into engagement with the rocker  110 , the valve  5  closes under the action of a valve return spring and the rocker arm  110  moves back into the position of  FIGS. 1 and 2  and the spring  6  causes the latch pin  1  to move back into the unlatched position. 
     Specifically, in this configuration (see e.g.  FIG. 1 ) the base circle  4   b  of the cam  4  exerts relatively little force onto the inner body  3  of the rocker arm  110 , which in turn exerts relatively little or no force onto the latch pin contact surface  1   d  of the lip section  1   c  of the latch pin  1 . As a result, the force of the spring  6  biasing the latch pin  1  to the unlatched position may be greater than the friction between the latch pin contact surface  1   d  and the inner body  3  of the rocker arm  110 , and hence the latch pin  1  may be caused to move to the unlatched configuration, where the inner body  3  and the outer body  7  are unlatched. 
     If the actuator  2  remains activated, then the actuator  2  will keep the latch pin  1  in the latched position when the base circle  4   a  of the cam is engaged with the follower  17  of the rocker arm  110  (as in  FIG. 2 ). However, if the actuator  2  is deactivated, when the base circle  4   b  of the cam is engaged with the follower  17  of the rocker arm  110 , the latch pin  1  may return under the force of the spring  6  to the unlatched position (as in  FIG. 1 ). 
     Accordingly, in this arrangement the latching system  120  requires a force from the actuator  2  to maintain the latch pin  1  in the latched position only when the rocker arm  110  engages the base radius  4   b  of the cam  4 . When the rocker arm  110  engages a lift profile  4   a  of the cam  4 , the latch pin  1  remains in the latched position without any action of the actuator  2  which allows for intermittent or no contact between the actuator arrangement and the latching arrangement in this condition. 
     Advantageously, this means that the geometry/shape of the actuator can be smaller than that of known arrangement where the actuator must be in permanent contact with the latching arrangement to maintain the latch pin in the latched position. Further this may allow for reduced wear between the actuator  2  and the latch pin  1 , as there is only intermittent rather than permanent contact between the actuator  2  and latch pin  1 . 
       FIGS. 4 and 5  illustrate a dual body rocker arm  310  arrangement of a valve train assembly  300  according to a second example that is very similar to the one described above. In this arrangement, the main difference is that latch arrangement  320  may also comprise a second spring (a so-called compliance biasing unit or spring)  23  that is on an outer section of the latch pin  201  and is arranged between outer  25  and inner  27  (e.g. a spring washer) compliance spring retainer components. 
     Further, in this arrangement, the actuator arrangement  202  comprises a cam lobe  30  supported on a shaft  32  that is rotatable by an actuator. 
     The rocker arm  310  may function in a very similar way to the rocker arm  110  described above. Components of the rocker arm  310  and the latching arrangement  320  that are the same or similar to components of the rocker arm  110  and the latching arrangement  120  are given reference numerals that are increased by two hundred compared to those used above. 
     In this example, the latching arrangement  320  comprises a latch pin  201 , a piston member  25 , a compliance biasing unit or spring  23 , and a latch pin return spring  206 . 
     The latching arrangement  320  is located in a bore or channel  228  formed in the outer body  11 . The bore  228  is a stepped bore and comprises a first section  228   a , a second section  228   b  and a third section  228   c . The first section  228   a  has an open end at the first end  310   a  of the rocker arm  310  and the third section  228   c  has an open end that faces the inner body  203 . The second section  228   b  is between and connects the first section  228   a  and the third section  228   c . The width (e.g. diameter) of the first section  228   a  is greater than the width of the second section  228   b  which is greater than width of the third section  228   c.    
     The latch pin  201  comprises a main body portion  201   a , a first end portion  201   b  and a second end portion  201   c . The first end portion  201   b  faces the inner body  203  and comprises a lip section  201   d  that extends from the main body portion  201   a  and defines a latch pin contact surface  201   e . The second end portion  201   c  is a shoulder portion of smaller diameter than the main body portion  201   a  and extends from the main body portion  201   a.    
     The latch pin  201  is located in a bore or channel  228  formed in the outer body  207  at a first end  310   a  of the rocker arm  310 . The outer body  207  is shaped so the bore or channel  228  opens out or widens or flares at the first end  310   a  of the rocker arm so that although at least a portion of the piston member  25  is within the bore or channel  228  (which provides for compactness) much of the piston member  25  is visible. 
     The piston member  25  is a hollow member that has a longitudinal aperture that is slightly wider than the second end portion  201   c  of the latch pin  201  (e.g. it has a slightly wider diameter) and which is mounted in sliding contact along substantially all of its length on the second end portion  201   c  of the latch pin  201 . A stopper ring  280 , for example a C-clip, received in a notch formed around an outermost end of the second end portion  201   c  acts to limit the extent of the expansion stroke of the piston member  25 . 
     The second end portion  201   c  also passes through an aperture of the retainer ring  27  which sits tightly on the second end portion  201   c  facing the piston member  25  and resting against the main body portion  201   a  of the latch pin  201 . The compliance spring  23  is between a flared or flange end portion  25   a  of the piston  25  and the retainer ring  27 . The return spring  206  sits around the main body portion  201   a  of the latch pin  201  between the retainer ring  27  and a part of the outer body  207 . 
     An orientation pin  292  (e.g. a dowel pin) is also provided to help maintain the orientation of the latch pin  201 . 
     As mentioned above, in this example, the actuator arrangement  202  comprises a cam lobe  30  supported on a shaft  32  that is rotatable by an actuator. When it is required that the rocker arm  310  be in the first (latched configuration), for example to provide for a first valve lift mode, the actuator may be controlled to rotate the shaft  32  so that a lobed portion  30   a  of the cam lobe contacts the latching arrangement  320 , for example to apply a force to the piston member  25 . 
     The biasing or spring force (e.g. stiffness) of the compliance spring  23  is much higher than that of the return spring  206  and so accordingly the force of the actuator arrangement  202  pushing on the piston member  25  is transmitted to the latch pin  201  through the compliance spring  23  as the piston member  25  moves in the first section of the bore  228  and the latch pin  201 , which is free to move, is caused to move against the bias of the return spring  206  into a fully extended position in which it latches the inner body  203  and outer body  207  together. In this position, the flat contact surface  201   e  of the latch pin  201  engages a corresponding contact surface  203   a  of the inner body  203 . 
     In this first (latched) configuration, the rocker arm  310  will function as previously described above in response to the rotating cam. In particular, as illustrated in  FIG. 5 , the lift profile of a cam engaging with a follower  217  of the inner body  203  causes the rocker arm  310  to pivot about a HLA (not shown in  FIG. 5 ) to cause a valve lift to open the valve (not shown in  FIG. 5 ), the movement of the rocker arm  310  causes the actuator arrangement  202  to lose contact with the latch arrangement  320  (see e.g. gap  333  of  FIG. 5 ), but the frictional force generated by the contact between inner body  203  and the latch pin  201  is sufficient to overcome the return force of the spring  206  so that the inner body  203  and the outer body  207  remain latched. 
     When it is required that the rocker arm  310  be in the second (unlatched configuration), for example to provide for a second valve lift mode, the actuator may be controlled to rotate the shaft  32  so that a base circle portion  30   b  of the cam  30  faces towards the latching arrangement  320  (such that the lobed portion  30   a  of the cam does not contact the latching arrangement  320 ). In this case, the return spring  206  causes the latch pin  201  and the piston member  25  to return to the fully retracted position. 
     If the actuator arrangement  202  applies a force to the piston member  25  to try to cause the latch pin  201  to move from the fully retracted position (i.e. unlatched position) to the fully extended position (i.e. latched position) at a time when the latch pin  201  is unable to move (not illustrated), the actuator arrangement  202  causes the piston member  25  to slide along the second end portion  201   c  of the latch pin to compress the compliance spring  23 . 
     The latch pin  201  may be prevented from moving, for example, because for example, the inner arm  203  is pivoted relative to the outer body  207  and has not yet returned to the position it adopts when the cam base circle (not shown in  FIGS. 4 and 5 ) is engaged with the roller follower  217 . In such a case, the inner arm  203  physically abuts the latch pin  201  and prevents it from moving into the latched position (not illustrated). 
     However, when the inner arm  203  has completed its return stroke (i.e. it is back in the position it adopts when the cam base circle engages the roller follower  217 ) so that the latch pin  201  is free to move again, the force generated by the compressed compliance spring  23  as it de-compresses is stronger than the force required to overcome the return spring  206  and so causes the latch pin  201  to move into the fully extended position in which it latches the inner arm  203  and the outer arm  207  together (as illustrated in  FIG. 4 ). 
     Advantageously, because the compliance spring  23  and piston member  25  arrangement will ensure that the latch pin  201  is moved into the latching position, there is no need to carefully control the timing of the actuator arrangement  202  to be synchronous with the inner arm  203  ending its return stroke. 
     In either of the above examples, the actuator arrangement  2 ,  202  may take any suitable form and may include one or more mechanical cam arrangements, electro-magnetic actuators, hydraulic actuators or combinations thereof. 
     Either of the first and second configuration described above may provide for any switchable valve operating mode, for example an exhaust deactivation mode, variable valve timing mode, exhaust gas recirculation mode, compression brake mode etc. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments. 
     The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C. 
     LIST OF REFERENCE SIGNS 
     
         
           1 ,  201  Latching pin 
           1   a  first end portion of latch pin 
           1   b  second end portion of latch pin 
           1   c ,  201   d  lip section of latch pin 
           1   d ,  201   e  latch pin contact surface 
           2 ,  202  actuator arrangement 
           3 ,  203  inner body 
           4 ,  204  cam 
           4   a , lift profile 
           4   b  base circle 
           5  valve 
           6 ,  206  return spring 
           7 ,  207  outer body 
           7   a  side wall 
           9  pivot axis 
           11  Hydraulic Lash Adjuster (HLA) 
           11   d  recess 
           17 ,  217  cam follower 
           19  axle 
           23  compliance biasing unit 
           25  piston member 
           25   a  flange end portion 
           27  retainer ring 
           28 ,  228  bore 
           28   a ,  228   a  first section of bore 
           28   b ,  228   b  second section of bore 
           30  cam lobe 
           30   a  lobed portion 
           30   b  base circle portion 
           32  shaft 
           40  housing 
           41  bore 
           42  actuating member 
           100 ,  300  valve train assembly 
           110 ,  310  dual body rocker arm 
           110   a ,  310   a  first end of rocker arm 
           110   b ,  310   b  second end of rocker arm 
           120 ,  320  latching arrangement 
           201   a  main body portion of latch pin 
           201   b  first end portion of latch pin 
           201   c  second end portion of latch pin 
           228   c  third section of bore 
           280  stopper ring 
           292  orientation pin