WO2019122261A1

WO2019122261A1 - Actuation apparatus comprising position sensor

Info

Publication number: WO2019122261A1
Application number: PCT/EP2018/086432
Authority: WO
Inventors: Nicola Andrisani; Emanuele RAIMONDI
Original assignee: Eaton Intelligent Power Limited
Priority date: 2017-12-21
Filing date: 2018-12-20
Publication date: 2019-06-27

Abstract

An actuation apparatus (200') for actuating a component (4) of a switchable valve train device (2) of an internal combustion engine, is disclosed. The actuation apparatus (2) comprises a contacting element (212') for contacting the component (4) of the switchable valve train device (2). The contacting element (212') is movable by an actuation source (3) in use between a first position for actuation of the component (4) of the switchable valve train device (2) and a second position for de-actuation of the component (4) of the switchable valve train device (2) in use. The actuation apparatus comprises a position senor (252) arranged to sense the position of at least a first portion (254) of the contacting element (212') relative to the position sensor (252) thereby to sense whether the contacting element (212') is in the first position or the second position. A method is also disclosed.

Description

ACTUATION APPARATUS COMPRISING POSITION SENSOR

Technical Field

The present invention relates to actuation, and more specifically actuation of components of switchable valve train devices of an internal combustion engine, and to position sensing relating to same.

Background

Internal combustion engines may comprise switchable engine or valve train devices. For example, valve train assemblies may comprise a switchable rocker arm to provide for control of valve 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 to provide one mode of operation (e.g. a first valve-lift 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). Typically, a moveable latch pin is used and actuated and de-actuated to switch between the two modes of operation.

WO 2013/156610 Al [EATON SRL] discloses such a switchable rocker arm with a moveable latch pin. The default position of the latch pin is unlatched, and it is retained in this position using biasing means. When required, the latch pin is actuated to the latched position using an external actuation mechanism based on a leaf spring. When actuation is required, the leaf spring is controlled to rotate a certain amount so as to engage with a roller of the latch pin, and hence push the latch pin into the latched position. In this way, the mode of operation that the switchable rocker arm provides for is controlled, for example, to provide for internal Exhaust Gas Recirculation. Summary

According to a first aspect of the present invention, there is provided an actuation apparatus for actuating a component of a switchable valve train device of an internal combustion engine, the actuation apparatus comprising: a contacting element for contacting the component of the switchable valve train device, the contacting element being movable by an actuation source in use between a first position for actuation of the component of the switchable valve train device and a second position for de-actuation of the component of the switchable valve train device in use; and a position senor arranged to sense the position of at least a first portion of the contacting element relative to the position sensor thereby to sense whether the contacting element is in the first position or the second position.

Optionally, the position sensor is arranged to produce, in use, a signal indicative of a proximity of the first portion of the contacting element relative to the position sensor.

Optionally, the actuation apparatus comprises an engine control unit arranged to receive, in use, said signal from the position sensor, and to determine, on the basis thereof, whether the component of the switchable valve train device is actuated or de- actuated.

Optionally, the first portion of the contacting element is located at or towards a contact portion of the contacting element, the contact portion being for contacting the component of the switchable valve train device.

Optionally, the position sensor comprises an inductive proximity sensor, and wherein the first portion of the contacting element is or comprises a magnetisable material. Optionally, the contact portion of the contacting element defines a contact surface for contacting the component of the switchable valve train device in use, and a target surface of the first portion arranged for sensing by the position sensor extends substantially perpendicularly to the contact surface.

Optionally, the actuation apparatus comprises a shaft rotatable by the actuation source, and the contacting element is rotatable by the shaft between the first position and the second position.

Optionally, the contacting element extends radially from the shaft, and the first portion is at or towards an end of the contacting element distal from the shaft.

Optionally, the actuation apparatus comprises a support supporting the shaft, and the position sensor is fixed relative to the support.

Optionally, the actuation apparatus comprises a plurality of said contacting elements each for contacting a said component of one of a respective plurality of said switchable valve train devices; and a respective plurality of said position sensors, each position sensor arranged to sense the position of a respective one of the plurality of contacting elements.

According to a second aspect of the present invention, there is provided a valve train assembly comprising the actuation apparatus according to the first aspect, and a said switchable valve train device comprising a said component.

Optionally, the switchable valve train device is a switchable rocker arm comprising a first body and a second body, and the component of the switchable rocker arm is a latching arrangement comprising a moveable latch pin for latching the first body and the second body together. Optionally, in use, when the contacting element is moved from the second position to the first position, the contacting element actuates the latching arrangement of the rocker arm so as to move the latch pin from an unlatched position in which the first body and the second body are unlatched so that the first body and the second body are moveable relative to one another so that the switchable rocker arm is configured for a first mode of operation, to a latched position in which the first body and the second body are latched together so that the switchable rocker arm is configured for a second mode of operation.

Optionally, the second mode of operation is internal exhaust gas recirculation. According to a third aspect of the present invention, there is provided a method of determining actuation, by an actuation apparatus, of a component of a switchable valve train device of an internal combustion engine, the actuation apparatus comprising: a contacting element for contacting the component of the switchable valve train device, the contacting element being movable by an actuation source in use between a first position for actuation of the component of the switchable valve train device and a second position for de-actuation of the component of the switchable valve train device in use; and a position senor arranged to sense the position of at least a first portion of the contacting element relative to the position sensor; the method comprising: receiving a signal from the position sensor and determining, on the basis thereof, whether the contacting element is in the first position or the second position.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings. Brief Description of the Drawings

Figure 1 illustrates schematically a perspective view of a valve train assembly according to an example; Figure 2 illustrates schematically a perspective view of a portion of the valve train assembly of Figure 1;

Figure 3 illustrates schematically a perspective view of a valve train assembly according to a second example; and

Figure 4 illustrates schematically a side view of a portion of the valve train assembly of Figure 3.

Detailed Description

Referring to Figures 1 and 2, a valve train assembly 1 of an internal combustion engine (not shown) comprises an actuation apparatus 200. The actuation apparatus 200 is arranged to actuate a component 4 of a switchable valve train device 2 of the valve train assembly 1. In this example, the switchable valve train device 2 is a switchable rocker arm 2, and the component 4 of the switchable rocker arm 2 is a moveable latching arrangement 4 of the rocker arm 2.

In the example illustrated in Figure 1, the valve train assembly lcomprises four rocker arms 2 each having a respective latching arrangement 4. Each switchable rocker arm 2 is arranged to control opening and closing of a respective valve 40, for example an exhaust valve 40, of a cylinder (not shown) of the overall internal combustion engine (not shown). Each latching arrangement 4 comprises a moveable latch pin 80 for latching an inner body 8 and an outer body 10 of the respective rocker arm 2 together. The actuation apparatus 200 transmits an actuation signal (force) from an actuation source 3 to the latch pin 80 of each switchable rocker arm 2.

For each switchable rocker arm, the inner body 8 and an outer body 10 may be latched together by the moveable latch pin 80 to provide one mode of operation (e.g. a first valve-lift mode, e.g. a dual valve lift mode where the corresponding valve 40 is opened for example twice per engine cycle, for example to provide for internal exhaust gas recirculation (iEGR)) and 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. a single lift mode where the valve 40 is opened for example once per engine cycle, for example to provide for a‘normal’ engine operation mode).

Specifically, in this example, for each rocker switchable rocker arm 2, the outer body 10 and the inner body 8 are pivotably connected together at a pivot axis 12. A first end of the outer body 10 contacts a valve stem 40a of the valve 40 and a second end of the outer body 10 contacts a hydraulic lash adjuster (HLA) 6. The outer body 10 is arranged to move or pivot about the HLA 6. The rocker arm 2 further comprises at the second end of the outer body 10 the latching arrangement 4 comprising the latch pin 80. The latch pin 80 is moveable between a first position in which the outer body 10 and the inner body 8 are un-latched and hence can pivot with respect to each other about the pivot axis 12 and a latched position in which the outer body 10 and the inner body 8 are latched together and hence can move or pivot about the HLA 6 as a single body.

The latching arrangement 4 comprises a biasing element 11 that biases the latch pin 80 to the unlatched position. Therefore, in a default state, i.e. when substantially no actuation force is applied to the latching arrangement 4 by the actuation apparatus 200, the latch pin is urged by the biasing element 11 to its default, unlatched, position.

The inner body 8 is provided with an inner body cam follower 26, for example, a roller follower 26 for following a secondary lift cam (not shown). The outer body 10 is provided with a pair of roller followers 22a, 22b, for example, main lift rollers 22a, 22b arranged either side of the roller follower 26 for following a pair of main lift cams (not shown). The rocker arm 2 further comprises a return spring arrangement 67 for returning the inner body 8 to its rest position after it is has pivoted with respect to the outer body 10.

When the latch pin 80 of a given rocker arm 2 is in the latched position, that rocker arm 2 provides a first function, for example, a dual lift mode to provide for iEGR, for example. When the latch pin of that rocker arm 2 is in the unlatched position, that rocker arm 2 provides a second function, for example, a single lift mode to provide for normal engine operation.

It will be appreciated that the rocker arm 2 may be any rocker arm comprising a plurality of bodies that move relative to one another, and which are latched together to provide one mode of operation (valve-lift mode) and are unlatched, and hence can move with respect to each other, to provide a second mode of operation (valve-lift mode). For example, rocker arm 2 may configured for internal Exhaust Gas Recirculation (iEGR), Cylinder Deactivation (CD A), Early Exhaust Valve Opening (EEVO), or the like applications.

The actuation apparatus 200 comprises a transmission lever 208 for contacting with the actuation source 3, a shaft 210 that is mechanically coupled to the transmission lever 208 such that the shaft 210 is rotatable by the actuation source 3, a shaft support body (not shown in Figures 1 and 2) arranged to support the shaft 210, a plurality of contacting elements 212 each for contacting the latching arrangement 4 of a respective one of the plurality of the rocker arms 2, and a respective plurality of biasing means 214 (also referred to herein as a compliance springs 214) to bias each contacting element 212 rotationally with respect to the shaft 210. The actuation apparatus 200 also comprises a respective plurality of preload elements 226, each attached to the shaft 210, and each for transferring a torque to a respective one of the biasing means 214 from the shaft 210. Each pre-load element comprises a radial protrusion 226a for contacting and applying the torque to the respective biasing means 214.

The actuation apparatus 200 is arranged to actuate the latching arrangement 4 of each rocker arm 2 by moving the latch pin 80 of each rocker arm 2 from the unlatched position to the latched position. Each contacting element 212 is movable by the actuation source 3 in use between a first position for actuation of the respective latching arrangement 4 of the respective switchable rocker arm 2, and a second position for de-actuation of the respective latching arrangement 4 of the switchable rocker arm 2.

A given biasing means 214 becomes biased by the shaft 210 when the actuation source 3 rotates the shaft 210 (via the lever 208) when the actuation source 3 attempts to actuate the latch pin 80 of a respective rocker arm 2, via the respective contacting element 212, at a time when the respective latch pin 80 cannot be actuated, for example, at a time when the relative orientation of the outer body 10 and the inner body 8 prevents the latch pin 80 from being able to move. The biasing means 214 so energised can then cause the respective contacting element 212 to actuate the latch pin 80 of the respective rocker arm 2 when the latch pin 80 next becomes actuatable.

The actuation source 3 comprises a drive rod (not visible) that can be controlled to rotate about its axis. For example, the rod (nots visible) may be caused to rotate when switching of a mode of operation of the switchable rocker arm is required. The actuation source 3 comprises a drive means 3a that is controllable to cause the rod (not visible) to rotate. The drive means 3a is in this example an electric motor, for example an electric torque motor. The rod (not visible) may be controlled to rotate using any suitable drive means 3 a, such as electrical, hydraulic, and/or pneumatic means.

The rod (not visible) has a coupler 218 extending radially therefrom for contacting with the lever 208 and transforming, via the lever 208, the rotational movement of the drive rod (not visible) about the axis of the drive rod 216 into rotational movement of the shaft 210 about the axis of the shaft 210. The axis of the shaft 210 is perpendicular to the axis of the rod (not visible). The coupler 218 is L shaped and has a mouth portion 220 for receiving therein the lever 208.

The lever 208 is mechanically coupled to the shaft 210, and extends radially therefrom.

The shaft 210 is mechanically coupled to each contacting element 212 via a respective one of the biasing means 214. Each biasing means (compliance spring) 214 may be for example a coil spring 214 wrapped around the shaft 210 (or a component 226 thereof). In this example, each compliance spring 214 is a coil spring 214 wrapped around a respective pre-load element 226 which itself is arranged around the shaft 210. As perhaps best seen in Figure 2, a first end 2l4a of each compliance spring 214 contacts the radial protrusion 226a of the respective pre-load element 226, and a second end 214b of each compliance spring 214 contacts a respective one of the contacting elements 212 thereby to bias the respective contacting element 212 rotationally with respect to the shaft 210, towards the respective rocker arm 2. When the shaft 210 rotates, the radial protrusion 226a of each pre-load element 226 applies a torque force to the respective compliance spring 214, thereby energising the compliance spring 214. Therefore, the shaft 210 may rotate with respect to each contacting element 212, but in doing so the respective biasing means (compliance spring) 214 will become energised, and will urge the corresponding contacting element 212 to follow the rotation of the shaft 210.

Each contacting element 212 is generally elongate and extends radially from the shaft 210. Each contacting element 212 has a generally flat main portion 260. Generally central of the main portion 260 is a connecting portion 262 for connecting the contacting element 212 to the shaft 210. The connecting portion 262 comprises a pair of wings 262a extending substantially perpendicularly from the main portion 260. Each wing 262a defines an aperture or slot 264 into which the shaft 210" is received. As perhaps best seen in Figure 2, each contacting element 212 has at a first end 2l2a, a contacting portion 228 that contacts with the latching arrangement 4 of the respective rocker arm 2. Each contacting portion 228 may be or comprise a flexible strip 228 and/or may be hook shaped. In this example, each contacting portion 228 defines a curved contact surface 228a for contacting the respective latching arrangement 4 so as to reduce wear of the contact surface and to enable the contacting element 212 to apply a force on the respective latch pin 80 towards the outer body 10 of the respective rocker arm 2 regardless of rotation of the outer body 10 about the hydraulic lash adjuster 6 during the engine cycle.

When actuation of each latch pin 80 is required, the rod (not visible) rotates clockwise (when looking along the rod (not visible) towards the drive means 3 a) which causes, via the lever 208, the shaft 210 to rotate anticlockwise (when looking along the shaft 210 towards the contacting element 212 from the lever 208), which causes each contacting element 212 to be urged, via the respective biasing means 214, into rotation anticlockwise (when looking along the shaft 210 towards the contacting element 212 from the lever 208) to contact the latching arrangement 40 of the respective rocker arm 2. Specifically, the rotation of the shaft 210 anticlockwise (when looking along the shaft 210 towards the contacting element 212 from the lever 208, in the sense of Figure 7) causes the radial protrusion 226a of each pre-load element 226 to exert a torque force on each respective compliance spring 214, which in turn causes each respective contacting element 212 to be urged into rotation anticlockwise (when looking along the shaft 210 towards the contacting element 212 from the lever 208) to contact the latching arrangement 4 of each respective rocker arm 2, thereby to urge the latch pin 80 of each respective rocker arm 2 towards and into each respective rocker arm 2. In other words, each contacting element 212 exerts a force on the respective latch pin 80 in a direction towards the inner body 8 and the outer body 10 of the respective rocker arm 2.

For a given rocker arm 2, if the latch pin 80 of the rocker arm 2 is free to move then the force of the contacting element 212 pushing against the latching arrangement 40 will be sufficient to actuate the latch pin 80 immediately, hence latching the inner body 8 and the outer body 10 together. That rocker arm 2 may therefore be immediately switched from, say, a second lift mode (e.g. single lift mode) to a first lift mode (e.g. dual lift mode).

However, in some cases, for a given rocker arm 2, the latch pin 80 may not be free to move (i.e. it may be blocked). For example, the actuation of the latch pin 80 may not be possible immediately due to an engine condition. For example, a lift profile (not shown) of a secondary lift cam (not shown) may be engaged with a secondary lift roller follower 26 of the inner body 8 of the given rocker arm 2. In this case, the inner body 8 will be rotated with respect to the outer body 10, hence blocking the path of the latch pin 80 from moving from the unlatched position to the latched position. In this case, the corresponding contacting element 212 will be restricted (blocked) from rotating with the shaft 210 when the shaft 210 is caused to rotate, and instead the rotation of the shaft 210 will cause the corresponding biasing means (compliance spring) 214 to be energised. As soon as (i.e. the instant that) the latch pin 80 becomes free to move again (i.e. becomes unblocked, e.g. as soon as the secondary lift roller follower 26 is engaged with a base circle (not shown) of the secondary lift cam (not shown) and hence the inner body 8 is no longer blocking the path of the latch pin (not shown)), the energy stored in the biasing of the spring 214 will cause the contacting element 212 to rotate anticlockwise about the shaft 210 (when looking along the shaft 210 towards the contacting element 212 from the lever 208), and hence cause the latch pin (not visible) to actuate, hence latching the inner body 8 and the outer body 10' together (and hence switching the rocker arm 2 from, say, a second lift mode (e.g. single lift mode) to a first lift mode (e.g. dual lift mode) as described above). At a later stage, the drive rod 216 of the actuator 3 may return to its original position (e.g. when de-actuation of each latch pin 80 is required), and hence each contacting element 212 ceases to apply a force on its respective latching arrangement 40, and hence each latch pin 80 may return to its default, unlatched position under force of the biasing element 11 that biases the latch pin 80 to its default, unlatched position.

The electromechanical actuation apparatus 200 described above has advantages over hydraulic based actuation systems, such as those using oil, in that oil or other hydraulic fluid is not necessary for actuation of the components of the rocker arms. Further, as described above, the actuation apparatus 200 allows for control of, for example, whether the rocker arms provide for a normal mode of engine operation or, for example, an iEGR mode of operation (which as is well known may reduce NOx emissions). Hence the actuation apparatus 200 may allow for an improved performance of the engine in terms of emissions, as well as for other improvements, for example, fuel consumption.

In the cases where such switchable systems are used in the control of the engine emission, it may be desirable (and indeed may be, for example, a legal requirement) for an on-board diagnostic system to be able to detect any mis-actuation of the emission related switchable system (for example a failure of the actuation as described above with reference to Figures 1 and 2).

The actuation source 3a may be controlled by, or otherwise in communication with, an engine control unit (not shown). The engine control unit may provide control signals to the actuation source 3a to control the actuation source to actuate or de- actuate, via the actuation apparatus 200, the latching arrangements 4 of the rocker arms 2. In one example, the actuation source 3a, for example the electric motor 3a described above with reference to Figures 1 and 2, may comprise a sensor (not shown) arranged to sense whether the rod (not shown), whose rotation causes the actuation of the latching arrangements 4 of the rocker arms 2 via the actuation apparatus 200, is in an actuation orientation for actuating the latching arrangement 4, or is in a non actuation orientation for allowing the latching arrangements 4 to be de-actuated. The engine control unit (not shown) may be provided with input from the sensor, and hence be able to determine diagnostic information on whether or not rotation of the rod is indeed occurring when the engine control unit controls the actuation source 3 a to rotate the rod, and therefore diagnostic information on whether or not actuation of the latching arrangements 4 of the rocker arms 2 is indeed occurring when the engine control unit controls the actuation source 3a to rotate the rod. For example, if the actuation source 3a fails for some reason, then despite the engine control unit controlling the rod (not visible) to rotate, the sensor provides information to the engine control unit that the rod has in fact not rotated, and hence that there is a failure of the actuation apparatus 200.

However, the sensor of the actuation source 3a may not be able to detect all failure modes of the actuation source 3a and actuation apparatus 200. For example, if a portion of the actuation source 3a or actuation apparatus 200 fails such that actuation of the latching arrangements 4 of one or more of the rocker arms 2 does not occur, but that the rod nonetheless rotates as expected, then the sensor will not be able to detect such failure modes. It may therefore be desirable to provide for detection of further or all failure modes of the actuation apparatus 200. It may also be desirable to provide for redundancy of failure mode sensors, in order to help ensure that the diagnostic information at the engine control unit is accurate.

Figures 3 and 4 illustrate schematically a portion of valve train assembly 1", according to a second example. The valve train assembly 1" comprises an actuation apparatus 200". The valve train assembly 1" and/or the actuation apparatus 200" of this second example may be the same or similar to the valve train assembly 1 and/or the actuation apparatus 200 described above in the first example with reference to Figures 1 and 2. Features of the valve train assembly 1" or the actuation apparatus 200" of the second example that are the same or similar to features of the valve train assembly 1 or the actuation apparatus 200 of the first example will not be described in detail again for brevity but are given the same reference numerals except including a prime (").

Similarly to the actuation apparatus 200 of the first example, the actuation apparatus 200" of this second example is arranged actuate a component (not shown, but see e.g. latching arrangement 4 of Figures 1 and 2) of a switchable valve train device (not shown, but see e.g. rocker arm 2 of Figures 1 and 2) of an internal combustion engine (not shown). The actuation apparatus 200" comprises a plurality of contacting elements 212" (only one if shown in Figures 3 and 4, labelled“lever 212"” in Figure 3) each for contacting a component of a respective switchable valve train device (not shown in Figures 3 and 4).

Similarly to as in the first example, each contacting element 212" is movable by an actuation source (not shown, but see e.g. actuation source 3 of Figures 1 and 2) between a first position for actuation of the component of the switchable valve train device (not shown) and a second position for de-actuation of the component of the switchable valve train component (not shown), for example in the same way as described for the contacting elements 212 and rocker arm 2 of Figures 1 and 2. For example, in the first position the contacting 212" element may apply a force to a latching arrangement (not shown, but see e.g. actuation arrangement 4 of the first example) of a rocker arm (not shown, but see e.g. switchable rocker arm 2 of the first example) so as to cause actuation of that latching arrangement (not shown), whereas in the second position, the contacting element 212" may apply substantially no force to the latching arrangement, and hence the latching arrangement may be de-actuated under the force of a return spring (not shown, but see e.g. return spring 11 of the first example). For example, for a given contacting element 212", when the contacting element 212" is moved from the second position to the first position, the contacting element 12" actuates the latching arrangement (not shown) of the respective rocker arm (not shown) so as to move the latch pin (not shown, but see e.g. latch pin 80 of the first example) of that rocker arm (not shown) from an unlatched position in which the first body (not shown, but see e.g. inner body 8 of the rocker arm 2 of the first example) and the second body of the rocker arm (not shown, but see e.g. outer body 10 of the rocker arm 2 of the first example) are unlatched so that the first body (not shown) and the second body (not shown) are moveable relative to one another so that the switchable rocker arm (not shown) is configured for a first mode of operation (e.g. the normal operation mode as described above in the first example), to a latched position in which the first body and the second body (not shown) are latched together so that the switchable rocker arm (not shown) is configured for a second mode of operation (e.g. the iEGR mode of operation described above in the first example). When the contacting element 212" is moved from the second position to the first position, the latch pin (not shown) moves from the latched position to the unlatched position under the force of the return spring (not shown) of the rocker arm (not shown), for example.

Similarly to the first example, the actuation apparatus 200" comprises a shaft 210" rotatable by the actuation source (not shown), and the contacting element 212" is rotatable by the shaft 210" between the first position and the second position. The contacting element 212" extends radially from the shaft 210". A support 250 supports the shaft 210". The support 250 may be for example, fixed relative to the engine cylinder head (not shown). Each contacting element 212" is generally elongate, has a generally flat main portion 260", generally central of which is a connecting portion 262" for connecting the contacting element 212" to the shaft 210", the connecting portion 262" comprising a pair of wings 262a" extending substantially perpendicularly from the main portion 260", and each wing 262a" defining an aperture or slot 264" into which the shaft 210" is received. Each contacting element 212" comprises at a first end 2l2a" a contacting portion 228" that contacts with the latching arrangement (not shown) of the respective rocker arm (not shown). Each contacting portion 228" may be or comprise a flexible strip 228" and/or may be hook shaped, and each contacting portion 228" defines a curved contact surface 228a" for contacting the respective latching arrangement (not shown).

However, unlike the actuation apparatus 200 of the first example, the actuation apparatus 200" of this second example comprises a position senor 252 arranged to sense the position of at least a first portion 254 of the contacting element 212" relative to the position sensor 252, thereby to sense whether the contacting element 212" is in the first position or the second position. In this example, the position sensor 252 is fixed relative to the support 250, that is affixed to the support 250. The position sensor 252 is orientated towards the contacting element 2122 The position sensor 252 points towards the contacting element 212" along an axis parallel to but offset from the axis of rotation of the contacting element 212".

The first portion 254 of the contacting element 212 is located at or towards the first end 212a" of the contacting element 218, distal from the shaft 210", at or towards the contact portion 228 "of the contacting element 212" for contacting the latching arrangement (not shown) of the switchable rocker arm (not shown). Specifically, the first portion 254 extends substantially perpendicularly to the curved contact surface 228a", and extends in a plane perpendicular to the axis of rotation of the contacting element 212". The first portion 254 defines a target surface 256 arranged for sensing by the position sensor 252. The target surface 256 extends substantially perpendicularly to the contact surface 228a" and lies in a plane perpendicular to the axis of rotation of the contacting element 212". Hence, when the contacting element 212" rotates between the first position and the second position, the proximity of the first portion 254 and the target surface 256 relative to the fixed position sensor 252 changes. In this example, when the contacting element 212" is in the second, non actuating, position, the first portion 254 and target surface 256 are relatively proximal to the position sensor, whereas when the contacting element 212" is in the first, actuating, position, the first portion 254 and target surface 256 move away from the position sensor 252 and hence are relatively distal from the position sensor 252. The position sensor may therefore provide diagnostic information to an engine control unit 265 indicative of whether the contacting element 212" is in the first, actuating, position or in the second, non- actuating, position. The position sensor 252 may be non-contact. The position sensor 252 may comprise an inductive proximity sensor, and the first portion 254/target surface 256 of the contacting element 212" may be or comprise a magnetisable material. That is the first portion 254/target surface 256 of the contacting element 212" may be or comprise a material capable of being sensed by a non-contact inductive proximity sensor, for example a material having a suitable magnetic permeability, for example steel or the like. In some examples, magnetic, such as ferromagnetic, material may be used. It will be appreciated that in other examples other types of position sensors 252 other than inductive proximity sensors may be used, for example the position sensor 252 may be an optical based position sensor or the like.

The position sensor 252 is arranged to produce, in use, a signal indicative of a proximity of the first portion 254/target surface 256 of the contacting element 212" relative to the position sensor 252. For example, the position sensor 252 may output a voltage indicative of, for example proportional to, the proximity of the of the first portion 254/target surface 256 of the contacting element 212" relative to the position sensor 252.

The position sensor 252 may be fixed to the support 250 relative to the contacting element 212" such that when the contacting element 212" is in the second, non-actuating, position, the first portion 254/target surface 256 of the contacting element 212" is aligned with the position sensor 252, and such that when the contacting element 212" is in the first, actuating, position, the first portion 254/target surface 256 of the contacting element 212" is misaligned with the position sensor 252, for example the position sensor may be aligned instead with a gap 258 defined between the contact portion 228"of the contacting element 212" and the main portion 260" of the contacting element 212". Hence the signal provided by the position sensor 252 when the contacting element 212" is in the first position is different as compared that produced when the contacting element 212" is in the second position.

The position sensor 252 may be communicatively coupled to the engine control unit 265 via a connection 266. The engine control unit 265 may be arranged to receive, in use, the signal from the position sensor 252, and to determine, on the basis thereof, whether the contacting element 212" is in the first, actuating, position or the second, non-actuating, position. The engine control unit 265 may therefore determine on the basis of the signal from the position sensor 252, whether the latching arrangement (not shown) of the respective rocker arm (not shown) is actuated or de- actuated. For example, when the contacting element 212" is in the second, non actuating position, the position sensor 252 may produce a first“OFF” signal, from which the engine control unit 265 may determine that the latching arrangement of the rocker arm (not shown) is de-actuated, and hence that the rocker arm is configured for normal engine operation, for example. However, when the contacting element 212" is in the first, actuating position, the position sensor 252 may produce a second“ON” signal, from which the engine control unit 265 may determine that the latching arrangement of the rocker arm (not shown) is actuated, and hence that the rocker arm is configured for iEGR operation mode, for example.

The engine control unit 265 may therefore be able to determine diagnostic information on whether or not actuation of the latching arrangement (not shown) is indeed occurring when the engine control unit 265 controls the actuation source to cause actuation. This determination may be sensitive to all failure modes of the actuation source 3 and the actuation apparatus 200". For example, if any of the components of the actuation source 3, or any components of the actuation apparatus 200, from the lever (not shown, but see lever 208 in Figure 1) to the contacting element 212", fail, then when the engine control unit 265 controls the actuation source to cause actuation, the contacting element may not move to the first position, the signal produced by the position sensor will not change, and hence the engine control unit 265 may determine that there is a fault in the actuation apparatus 200". For example, the engine control unit 265 may determine a fault when an“OFF” signal is received from a position sensor 252 when an“ON” signal is expected (for example because the engine control unit 265 has controlled the actuation source (not shown) to cause actuation).

The position sensor 252 may be an alternative or in addition to the sensor of the actuation source (not shown), which may provide redundancy in the diagnostic information.

The position sensor may be associated with any one contacting element 218 among the contacting elements of the actuation apparatus 200". In some examples, the position sensor 252 may be associated with the contacting element 218 furthest from the actuation source (not shown) along the shaft 210" among the contacting elements 218. This may provide that any failure in the shaft 210" be detected by the engine control unit 265.

In some examples (not illustrated) the actuation apparatus 200" may comprise a plurality of the contacting elements 212" for contacting a latching arrangement of each of a respective plurality of rocker arms (i.e. as is the case in the example illustrated in Figures 1 and 2), and a respective plurality of the position sensors 252, each position sensor 252 arranged to sense the position of a respective one of the plurality of contacting elements 2122 The engine control unit 265 may be in communication with each of the plurality of position sensors 252. The engine control unit 265 may therefore be able to determine for each contacting element whether it is in the first position or in the second position, and hence determine whether the associated latching arrangement is actuated or de-actuated, and hence whether the associated rocker arm is configured for iEGR operation or for normal operation, for example. The engine control unit 265 may therefore provide diagnostic information for each of the contacting elements 212, and may provide for detection of all failure modes of the actuation apparatus 200" and the actuation source (not shown). For example, example, for each of the position sensors 252, if the engine control unit 265 is expecting an “ON” signal because for example the engine control unit has controlled the actuation source to cause actuation, but still in fact receives an“OFF” signal, for example even after a certain time period, for example after one engine cycle, then the engine control unit 265 may determine that there is a fault with the contacting element 212 or a component of the actuation apparatus 200 associated therewith. Having multiple position sensors 252 may also provide for redundancy in the failure detection, i.e. such that the engine control unit 265 is not reliant on any one sensor so as to detect a failure in the actuation apparatus 200" and provide diagnostic information.

The above examples may allow for an easy installation of the sensors 252 actuation apparatus 200" and the overall engine (not shown), with a minimum impact on the packaging of the engine or actuation apparatus 200", and for detection of the maximum possible failure modes of the actuation apparatus 200" by a simple sensor 252. This may provide for an improved, for example more reliable, on board diagnostics (OBD).

In some examples, the actuation transmission apparatus 200 may actuate different components of a different switchable valve train device, not necessarily a latching arrangement of rocker arm.

In accordance with the above examples, a method of determining actuation, by the actuation apparatus 200', of the component 4 (e.g. actuation source 4) of the switchable valve train device (2) (e.g. switchable rocker arm 2) may comprise receiving a signal (e.g. the“ON” or“OFF” signals described above) from the position sensor 252 and determining, on the basis thereof, whether the contacting element 212' is in the first position or the second position. The method may be performed, for example, by the engine control unit 265. The method may further comprise determining on the basis of the signal from the position sensor 252, whether the latching arrangement 4 of the corresponding rocker arm 2' is actuated or de-actuated, and hence for example whether the rocker arm 2' is configured for a normal operation mode or an iEGR operation mode. The method may also comprise determining on the basis of the signal from the position sensor 252, and on the basis of a command signal provided to the actuation source 3, whether there is a fault in the actuation apparatus 2002 For example, if the control signal is set to control the actuation source 3 to cause actuation, but still the signal from the position sensor 252 indicates that the contacting element is in the second, non-actuated position, then it may be determined that there is a fault in the actuation apparatus 200'. In examples where there are a plurality of position sensors 252, the method may comprise receiving signals from each of the position sensors 252 and determining on the basis thereof whether the latching arrangement 4 of each of the respective rocker arms 2 is actuated or de-actuated and/or whether each of the respective rocker arms 2 is configured for a normal operation mode or an iEGR operation mode and/or whether there is a fault in the actuation apparatus 200", as described above. All of the above examples are to be understood as illustrative examples only.

It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Reference Signs List

1, 1' valve train assembly

2, 2' rocker arm

3 actuation source

3a drive means

4 latching arrangement

6 hydraulic lash adjuster

8 inner body

10 outer body

11 return spring

12 pivot axis

22a, b main lift rollers

26 secondary lift roller

40 valve

4a valve stem

67 return spring arrangement

80 latch pin

200, 200' actuation apparatus 208 lever

210, 210' shaft

212, 212' contacting element

212a, 2l2a' first end

214 biasing means (compliance spring)

218 coupler

220 mouth portion

226 pre-load element

226a protrusion

228, 228' contacting portion

228a, 228a' contact surface

250 support

252 position sensor

254 first portion of contacting element

256 target surface

260, 260' main portion

262, 262' connecting portion

262a, 262a' wings

264, 264' aperture or slot

265 engine control unit

Claims

1. An actuation apparatus (200') for actuating a component (4) of a switchable valve train device (2) of an internal combustion engine, the actuation apparatus (2) comprising:

a contacting element (212') for contacting the component (4) of the switchable valve train device (2), the contacting element (212') being movable by an actuation source (3) in use between a first position for actuation of the component (4) of the switchable valve train device (2) and a second position for de-actuation of the component (4) of the switchable valve train device (2) in use; and

a position senor (252) arranged to sense the position of at least a first portion (254) of the contacting element (212') relative to the position sensor (252) thereby to sense whether the contacting element (212') is in the first position or the second position.

2. The actuation apparatus (200') according to claim 1, wherein the position sensor (252) is arranged to produce, in use, a signal indicative of a proximity of the first portion (254) of the contacting element (212') relative to the position sensor (252).

3. The actuation apparatus (200') according to claim 2, wherein the actuation apparatus (200') comprises an engine control unit (265) arranged to receive, in use, said signal from the position sensor (252), and to determine, on the basis thereof, whether the component (4) of the switchable valve train device (2) is actuated or de- actuated.

4. The actuation apparatus (200') according to any one of claim 1 to claim 3, wherein the first portion (254) of the contacting element (212') is located at or towards a contact portion (228') of the contacting element (212'), the contact portion (228') being for contacting the component (4) of the switchable valve train device (2).

5. The actuation apparatus (200') according to any one of claim 1 to claim 4, wherein the position sensor (252) comprises an inductive proximity sensor (252), and wherein the first portion (254) of the contacting element (212') is or comprises a magnetisable material.

6. The actuation apparatus (200') according to any one of claim 1 to claim 5, wherein the contact portion (228') of the contacting element (212') defines a contact surface (228a') for contacting the component (4) of the switchable valve train device (2) in use, and wherein a target surface (256) of the first portion (254) arranged for sensing by the position sensor (252) extends substantially perpendicularly to the contact surface (228a').

7. The actuation apparatus (200') according to any one of claim 1 to claim 6, wherein the actuation apparatus (200') comprises a shaft (210') rotatable by the actuation source (3), and the contacting element (212') is rotatable by the shaft (210') between the first position and the second position.

8. The actuation apparatus (200') according to claim 7, wherein the contacting element (212') extends radially from the shaft (210'), and wherein the first portion (254) is at or towards an end of the contacting element (212') distal from the shaft (210').

9. The actuation apparatus (200') according to claim 7 or claim 8, wherein the actuation apparatus (200') comprises a support (250) supporting the shaft (210'), and wherein the position sensor (252) is fixed relative to the support (250).

10. The actuation apparatus (200') according to any one of claim 1 to claim 9, wherein the actuation apparatus (200') comprises a plurality of said contacting elements (212') each for contacting a said component (4) of one of a respective plurality of said switchable valve train devices (2); and

a respective plurality of said position sensors (252), each position sensor (252) arranged to sense the position of a respective one of the plurality of contacting elements (212').

11. A valve train assembly ( ) comprising the actuation apparatus (200') according to any one of claims 1 to 10, and a said switchable valve train device (2) comprising a said component (2).

12. The valve train assembly ( ) according to claim 11, wherein the switchable valve train device (2) is a switchable rocker arm (2) comprising a first body (8) and a second body (10), and the component (4) of the switchable rocker arm (2) is a latching arrangement (4) comprising a moveable latch pin (80) for latching the first body (8) and the second body (10) together.

13. The valve train assembly (G) according to claim 12, wherein, in use, when the contacting element (212') is moved from the second position to the first position, the contacting element (212') actuates the latching arrangement (4) of the rocker arm (2) so as to move the latch pin (80) from an unlatched position in which the first body (8) and the second body (10) are unlatched so that the first body (8) and the second body (10) are moveable relative to one another so that the switchable rocker arm (2) is configured for a first mode of operation, to a latched position in which the first body (8) and the second body (10) are latched together so that the switchable rocker arm (2) is configured for a second mode of operation.

14. The valve train assembly (G) according to claim 13, wherein the second mode of operation is internal exhaust gas recirculation.

15. A method of determining actuation, by an actuation apparatus (200'), of a component (4) of a switchable valve train device (2) of an internal combustion engine, the actuation apparatus (2) comprising:

a position senor (252) arranged to sense the position of at least a first portion (254) of the contacting element (212') relative to the position sensor (252);

the method comprising:

receiving a signal from the position sensor (252) and determining, on the basis thereof, whether the contacting element (212') is in the first position or the second position.