A valve operating system comprising a lost motion component in parallel deployed within a rocker arm and a valve bridge

Abstract

The valve actuation system comprises a valve actuation motion source configured to provide a main valve actuation motion and an auxiliary valve actuation motion for actuating at least one engine valve via a valve actuation load path. A lost motion subtraction mechanism is disposed on a valve bridge and is configured to transmit at least the main valve actuation motion in a first default operating state and to lose the main valve actuation motion and the auxiliary valve actuation motion in a first activation state. Additionally, a lost motion addition mechanism is disposed on a rocker arm and is configured to lose the auxiliary valve actuation motion in a second default operating state and to transmit the auxiliary valve actuation motion in a second activation state, and the lost motion addition mechanism is in parallel with the lost motion subtraction mechanism in the valve actuation load path at least during a second operating state.

Description

Technical Field

[0001] (Cross - reference to related applications) The present disclosure generally relates to valve actuation systems, and more particularly to valve actuation systems having parallel lost motion components along a valve actuation load path, which can be used to implement both cylinder deactivation and auxiliary valve actuation.

Background Art

[0002] Valve actuation systems for use in internal combustion engines are well known in the art. During the positive power operation of an internal combustion engine, such a valve actuation system is used to provide a so - called main valve actuation motion to the engine valves in conjunction with the combustion of fuel, and as a result, the engine outputs power that can be used, for example, to operate a vehicle. Alternatively, the valve actuation system can be operated to provide a so - called auxiliary valve actuation motion in addition to or other than the main valve actuation motion. The valve actuation system can also be operated in such a way as to stop the operation of a given engine cylinder at one time, i.e., by removing the actuation of the engine valves, often called cylinder deactivation, so that it does not operate in either the main or auxiliary operating modes. As is further known in the art, it is possible to combine these various operating modes to provide desirable benefits. For example, future emission standards for large diesel trucks require technologies that improve fuel economy and reduce emissions. A major technology that provides both simultaneously is cylinder deactivation. It is well - documented that cylinder deactivation reduces fuel consumption, raises temperatures, and improves the control of after - treatment emissions.

[0003] A known system for cylinder deactivation is described in U.S. Patent No. 9,790,824, which describes a hydraulic control lost motion mechanism disposed in a valve bridge, an example of which is illustrated in FIG. 11 of the '824 patent and reproduced herein as FIG. 1. As shown in FIG. 1, the lost motion mechanism includes an outer plunger 120 disposed with a bore 112 formed in a body 110 of a valve bridge 100. A locking element in the form of a wedge 180 is provided, which is configured to engage an annular outer recess 172 formed in a surface defining the bore 112. When hydraulic control is not applied to the inner plunger 160 (in this case, via a rocker arm, not shown), the inner piston spring 144 extends the wedge 180 out of an opening formed in the outer plunger 120, thereby engaging the outer recess 172 and biasing the inner plunger 160 in place to effectively lock the outer plunger 120 in a predetermined position relative to the valve bridge body 110. In this state, any valve actuation motion (primary or auxiliary motion) applied to the valve bridge via the outer plunger 120 is transmitted to the valve bridge body 110 and ultimately to an engine valve (not shown). However, when sufficiently pressurized hydraulic fluid is supplied to the upper portion of the inner plunger 160, the inner plunger 160 slides downward, as a result of which the wedge 180 is retracted and can disengage from the outer recess 172, thereby effectively releasing the lock of the outer plunger 120 relative to the valve bridge body 110 and allowing the outer plunger 120 to freely slide within its bore 112 under the bias provided by the outer plunger spring 146 toward the rocker arm. In this state, any valve actuation motion applied to the outer plunger 120 causes the outer plunger 120 to reciprocate within its bore 112. Thus, assuming that the movement of the outer plunger 120 within the bore 112 is greater than the maximum range of any applied valve actuation motion, such valve actuation motion is not transmitted to the engine valve and is effectively lost such that the corresponding cylinder is deactivated.

[0004] However, one drawback of cylinder deactivation is that the energy of the exhaust system also decreases because the air flow rate passing through the engine decreases. During the warm-up of the vehicle from a cold start, it is important to raise the exhaust temperature and rapidly increase the catalyst temperature to an efficient operating temperature. Cylinder deactivation provides a temperature increase, but the significant reduction in air flow rate is not effective for rapid warm-up.

[0005] To overcome this drawback of cylinder deactivation and provide rapid warm-up, one proven technique is to advance the opening of the exhaust valve, called early exhaust valve opening (EEVO), to release additional thermal energy into the exhaust system, which is a specific type of auxiliary valve actuation motion in addition to the main valve event. In practice, such a system is based on the principle of adding valve actuation motion that is lost during the operation of the main valve to provide this early opening event. A system that combines both early exhaust opening and cylinder deactivation functions can meet the warm-up requirements, reduce emissions, and improve fuel consumption.

[0006] A valve actuation system for providing EEVO can be provided using a rocker arm having a hydraulically controlled lost motion component in the form of an actuator, as illustrated in U.S. Patent No. 6,450,144, an example of which is illustrated in FIG. 19 of the '824 patent and reproduced herein as FIG. 2. In this system, the rocker arm 200 is provided with an actuator piston 210 disposed at the motion imparting end of the rocker arm 200. The actuator piston 210 is biased outward of its bore by a spring 217 such that the actuator piston 210 continuously contacts the corresponding engine valve (or valve bridge). Hydraulic passages 231, 236 are provided such that hydraulic fluid can be supplied by the control passage 211 to fill the actuator piston bore. In these situations, the hydraulic fluid is retained within the bore by the check valve 241 and the actuator piston 210 is firmly maintained in the extended position and cannot reciprocate within its bore unless the hydraulic passage 236 is aligned with the control passage 211. On the other hand, when the bore is not filled with hydraulic fluid (or such hydraulic fluid is drained upon alignment of the noted passages 236, 211), the actuator piston 210 is free to reciprocate within its bore within the limits permitted by the lash adjusting screw 204. In such a system, the cam comprises cam lobes for providing both primary and secondary valve actuation motions. In the primary valve actuation operation, hydraulic fluid is not provided to the actuator piston 210 such that the actuator piston 210 is permitted to reciprocate within its bore. In this case, any valve actuation motion provided by the EEVO lobe is lost by the reciprocation of the actuator piston 210 as long as the amount of allowable movement of the actuator piston 210 into its bore is at least as large as the maximum motion provided by the EEVO lobe but less than the maximum motion provided by the primary event lobe. However, upon actuation of the primary event valve, the actuator piston 210 reaches the bottom within its bore (or through solid contact with other surfaces), thereby transmitting the primary event motion.On the one hand, position-based exhaust of the actuator bore (i.e., reset by alignment of the noted passages 236, 211) prevents excessive elongation of the engine valve during the main valve event motion. However, when the actuator piston is hydraulically locked in the extended position, the EEVO motion is not lost and is transmitted to the engine valve.

[0007] At least theoretically, it should be possible to combine lost motion-based cylinder deactivation with the above type of auxiliary valve actuation motion system to provide the desired cylinder deactivation and EEVO operation. However, simply directly combining such systems is not given to provide the desired result.

[0008] For example, as described above, the EEVO lost motion combines a normal main event lift with an early lift portion on the same camshaft. This example is illustrated in FIG. 3. In FIG. 3, the first curve 310 illustrates an idealized version of the main event valve lift having a maximum lift of approximately 14 millimeters in this example. The second curve 311 illustrates the typical actual main event that the engine valve would experience when the EEVO motion provided by the cam is lost. For example, the rocker arm actuator of FIG. 2 above can reciprocate. The upper dashed curve 312 illustrates the ideal valve lift when all valve actuation motion provided by the EEVO - compliant cam is provided, for example, when the rocker arm actuator is fully extended. As shown, the idealized lift 312 includes an EEVO event 313 of approximately 3 mm of valve lift during valve opening, which is actually converted to a valve lift 314 of approximately 2 millimeters. The example illustrated in FIG. 3 also shows the occurrence of a reset, whereby the actuator piston is allowed to drop, in this example, at approximately 10 mm of lift, (i.e., the locked hydraulic fluid in the actuator bore is vented for this cycle of the engine valve), thereby causing the normal lift main event 311 to occur. The combination of these two lift events (as illustrated by the ideal lift profile 312) results in a total stroke of approximately 17 mm, and when lost by the lost motion mechanism illustrated in FIG. 1, relatively high stress is placed on the outer plunger spring 146 when attempting to bias the outer plunger 120 over the entire 17 mm of movement of the outer plunger 120.

[0009] As an additional example, during cylinder deactivation as described above, it is known that the normal force applied by the engine valve spring to urge the rocker arm and continuously contact the valve actuation motion source (e.g., cam) is no longer provided. The outer piston plunger spring 146 returns some force toward the rocker arm via the outer plunger 120, but this force is relatively small and insufficient to control the rocker arm as needed. Thus, a separate rocker arm biasing element is typically provided to bias the rocker arm into contact with the cam, for example, by applying a biasing force toward the cam at the motion receiving end of the rocker arm via a spring located on the rocker arm. The inability to properly control the inertia presented by the rocker arm (due to valve actuation motion still being applied to the rocker arm despite it being deactivated) can cause the rocker arm and cam to separate, and as a result, there is a potential for harmful effects between the two. Similarly, the EEVO valve actuation motion lost when EEVO operation is not required still imparts inertia to the rocker arm that needs to be controlled as well. Such complex factors of operation by the rocker arm biasing element are that each of these operations (cylinder deactivation and EEVO) typically occur over significantly different speed ranges.

[0010] Typically, cylinder deactivation occurs typically at engine speeds of about 1800 rpm or less, and the rocker arm biasing element is configured to provide sufficient force at these speeds to ensure proper contact between the rocker arm and the cam. On the other hand, lost EVO valve actuation motion exists up to relatively high engine speeds (e.g., about 2600 rpm). Thus, to obtain the combined advantages of cylinder deactivation and EVO operation, the biasing element of the rocker arm needs to be able to handle the high speeds at which the actuation motion of the EVO valve can still be applied to the rocker arm. Because of the relatively high speeds at which they can still occur, rocker arm control for lost EVO valve actuation motion requires the application of high force by the rocker arm biasing element. However, this occurs at small valve lifts where the rocker arm biasing spring has its minimum preload. On the other hand, cylinder deactivation typically occurs at low speeds, over the higher lift portion (main valve actuation motion) where the biasing element of the rocker arm is at increased preload. However, the challenge of providing a rocker arm biasing element that can provide high force at minimum preload (required for EVO) and withstand the stresses required during full movement (required for cylinder deactivation) is difficult to overcome. SUMMARY OF THE INVENTION

[0011] The above drawbacks of the prior art solutions are addressed by providing a valve actuation system for actuating at least one engine valve in accordance with the present disclosure. In particular, the valve actuation system comprises a valve actuation motion source, such as a single cam, configured to provide a primary valve actuation motion and an auxiliary valve actuation motion for actuating at least one engine valve via a valve actuation load path. A lost motion subtraction mechanism is disposed within the valve bridge and is configured to transmit at least the primary valve actuation motion in a first default operating state and to lose the primary valve actuation motion and the auxiliary valve actuation motion in a first activation state. Additionally, a lost motion addition mechanism is disposed within the rocker arm and is configured to lose the auxiliary valve actuation motion in a second default operating state and to transmit the auxiliary valve actuation motion in a second activation state, and the lost motion addition mechanism is in parallel with the lost motion subtraction mechanism in the valve actuation load path at least during the second activation state.

[0012] Examples of the auxiliary valve actuation motion include at least one of an early exhaust valve opening valve actuation motion, a late intake valve closing valve actuation motion, or an engine brake valve actuation motion.

[0013] In one embodiment, the lost motion subtraction mechanism and the lost motion addition mechanism are used and the internal combustion engine further comprises an engine controller configured to operate the internal combustion engine. In a positive power mode, the engine controller controls the lost motion subtraction mechanism operating in a first default operating state and the lost motion addition mechanism operating in a second default operating state. In a rest mode, the engine controller controls the lost motion subtraction mechanism operating in a first activation operating state and the lost motion addition mechanism operating in a second default operating state. In an auxiliary mode, the engine controller controls the lost motion subtraction mechanism operating in a first default operating state and the lost motion addition mechanism operating in a second activation operating state.

[0014] The corresponding method is also disclosed.

Brief Description of the Drawings

[0015] The features described in this disclosure are set forth in detail in the appended claims. These features and attendant advantages will become apparent from the following detailed description when considered in conjunction with the accompanying drawings. Here, by way of example only, one or more embodiments will be described with reference to the accompanying drawings in which like reference numerals represent like elements.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Mode for Carrying Out the Invention

[0016] FIG. 4 schematically illustrates a valve actuation system 400 according to the present disclosure. In particular, the valve actuation system 400 includes a valve actuation motion source 402 that functions as the sole source of valve actuation motion (i.e., valve opening and closing motion) to one or more engine valves 404 via a valve actuation load path 406. The one or more engine valves 404 are associated with a cylinder 405 of an internal combustion engine. As is known in the art, each cylinder 405 typically has at least one valve actuation motion source 402 uniquely corresponding thereto for actuation of the corresponding engine valve 404. Further, although only a single cylinder 405 is illustrated in FIG. 4, an internal combustion engine may include two or more cylinders, and often does, and it is understood that the valve actuation system described herein is applicable to any number of cylinders of a given internal combustion engine.

[0017] The valve actuation motion source 402 may comprise any combination of known elements capable of providing valve actuation motion, such as a cam. The valve actuation motion source 110 may be dedicated to providing exhaust motion, intake motion, auxiliary motion, or a combination of exhaust or intake motion along with auxiliary motion. For example, in a presently preferred embodiment, the valve actuation motion source 402 may comprise a single cam configured to provide a primary valve actuation motion (exhaust or intake) and at least one auxiliary valve actuation motion. As a further example, if the primary valve actuation motion comprises a primary exhaust valve actuation motion, the at least one auxiliary valve actuation motion may comprise an EEVO valve event and / or a compression-release engine brake valve event. As yet another example, if the primary valve actuation motion comprises a primary intake valve actuation motion, the at least one auxiliary valve actuation motion may comprise a late intake valve closing (LIVC) valve event. Still further types of auxiliary valve actuation motions that may be combined on a single cam having a primary valve actuation motion may be known to those skilled in the art, and the present disclosure is not limited in this regard.

[0018] The valve actuation load path 406 is deployed between a valve actuation motion source 402 and at least one engine valve 404 and includes any one or more components used to transmit the motion provided by the valve actuation motion source 402 to the at least one engine valve 404, such as, for example, a tappet, a pushrod, a rocker arm, a valve bridge, an automatic lash adjuster, etc. Further, as shown, the valve actuation load path 406 also includes a lost motion adding (LM+) mechanism 408 and a lost motion subtracting (LM-) mechanism 410. As used herein, the LM+ mechanism is a mechanism that, by default or in a "normal" state (i.e., when the control input is not asserted), either can or cannot transmit any auxiliary valve actuation motion applied thereto and can transmit any primary valve actuation motion applied thereto. On the other hand, when the LM+ mechanism is in an activated state (i.e., when the control input is asserted), the mechanism transmits any auxiliary valve actuation motion applied thereto and also transmits any primary valve actuation motion applied thereto. Further, as used herein, the LM- mechanism is a mechanism that, by default or in a "normal" state (i.e., when the control input is not asserted), either can or cannot transmit any primary valve actuation motion applied thereto and can transmit any auxiliary valve actuation motion applied thereto. On the other hand, when the LM- mechanism is in an activated state (i.e., when the control input is asserted), the mechanism does not transmit any valve actuation motion applied thereto, whether primary or auxiliary valve actuation motion. In short, the LM+ mechanism, when activated, can add or include valve actuation motion associated with the default or normal operating state, while the LM- mechanism, when activated, can subtract or lose valve actuation motion associated with the default or normal operating state.

[0019] A variety of lost motion mechanisms that can function as an LM+ or LM- mechanism are well known in the art and include hydraulic or mechanically based lost motion mechanisms that can be hydraulically, pneumatically, or electromagnetically actuated. For example, the lost motion mechanism depicted in FIG. 1 and taught in U.S. Patent No. 9,790,824 (incorporated herein by reference) is an example of a hydraulically controlled mechanical lock LM- mechanism. As described above, in the absence of hydraulic fluid input to the inner plunger 160 (i.e., in the default state), the locking element 180 is received in the outer recess 772, thereby "locking" the outer plunger 120 to the body 120 such that the applied actuation motion is transmitted. On the other hand, when hydraulic fluid input is provided to the inner plunger 160 (i.e., when in the activated state), the locking element 180 can be retracted, thereby "unlocking" the outer plunger 120 from the body 120 such that the applied actuation motion is not transmitted or lost. As another example, the lost motion mechanism shown in FIG. 2 and taught in U.S. Patent No. 6,450,144 (the teachings of which are incorporated herein by reference) is an example of a hydraulically controlled hydraulic based LM+ mechanism. As described above, in the absence of hydraulic fluid input to passages 231, 236 (i.e., in the default state), the actuator piston 210 is free to reciprocate within its bore, and as a result, any applied actuation motion that is less than the maximum distance (actuator piston stroke length) that the actuator piston 210 can be retracted within its bore is not transmitted or lost, while any applied actuation motion that is greater than the actuator piston stroke length is transmitted.

[0020] As further depicted in FIG. 4, engine controller 420 can be provided and operably connected to LM+ and LM− mechanisms 408, 410. Engine controller 420 can include any electronic, mechanical, hydraulic, electro-hydraulic, or other type of control device for controlling the operation of LM+ and LM− mechanisms 408, 410, i.e., for switching between their respective default and startup operating states as described above. For example, engine controller 420 can be implemented by a microprocessor and corresponding memory that stores executable instructions used to implement the necessary control functions, including those described below, as is known in the art. It is understood that other functionally equivalent embodiments of engine controller 130, such as a suitable programmed application specific integrated circuit (ASIC), etc., can be equally used. Further, engine controller 420 can include peripheral devices intermediate engine controller 420 and LM+ and LM− mechanisms 408, 410 that enable engine controller 420 to achieve control over the operating states of LM+ and LM− mechanisms 408, 410. For example, if LM+ and LM− mechanisms 408, 410 are both hydraulic control mechanisms (i.e., responsive to the absence or application of hydraulic fluid to an input), they can include suitable solenoids, as is known in the art.

[0021] In system 400 illustrated in FIG. 4, the LM+ mechanism 408 is disposed closer to the valve actuation motion source along the valve actuation load path 406 than the LM− mechanism 410. Examples of such systems are described in more detail below with reference to FIGS. 6-12. However, this is not a requirement. For example, FIG. 5 illustrates a valve actuation system 400′, where like reference numerals refer to like elements, and the LM− mechanism 410 is disposed closer to the valve actuation motion source 402 than the LM+ mechanism 408. Examples of such systems are described in more detail below with reference to FIGS. 12 and 13. Additionally, in the systems illustrated in FIGS. 4 and 5, the LM+ mechanism 408 and the LM− mechanism 410 are illustrated as being in series with each other (at least during the second activation state of the LM+ mechanism). However, again, this is not a requirement. For example, FIG. 15 (described below) illustrates a valve actuation system 1500 where like reference numerals refer to like elements when compared to FIG. 4, and the LM− mechanism 410′ is disposed in parallel with the LM+ mechanism 408′ within the valve actuation load path 406. Examples of such systems are described in more detail below with reference to FIGS. 16-23.

[0022] Referring again to FIG. 4, the LM+ mechanism 408 is in series along the valve actuation load path 406 having the LM- mechanism 410 in all operating states of the LM+ mechanism 408. That is, as described above, regardless of whether the LM+ mechanism 408 is in its default state or its activated state, any primary valve actuation motion provided by the valve actuation motion source 402 is transmitted by the LM+ mechanism 408 to the LM- mechanism 410. However, this is also not a requirement as illustrated in FIG. 5 where the LM+ mechanism 408 is illustrated either in series or not in series with the LM- mechanism 410 as a function of the operating state of the LM+ mechanism 408. In this case, when the LM+ mechanism 408 is in its default operating state, i.e., when it is controlled to lose any auxiliary valve actuation motion applied thereto, the LM+ mechanism 408 does not play a role in transmitting the primary valve actuation motion transmitted by the LM- mechanism 410, which is illustrated by the solid line arrow between the LM- mechanism 410 and the engine valve 404. Effectively, in this state, the LM+ mechanism 408 is removed from the valve actuation load path 406 as depicted in FIG. 5. On the other hand, when the LM+ mechanism 408 is in its activated operating state, i.e., when it is controlled to transmit any auxiliary valve actuation motion applied thereto, the LM+ mechanism 408 is involved in transmitting both the primary valve actuation motion and the auxiliary valve actuation motion received from the LM- mechanism 410, thereby effectively placing the LM+ mechanism 408 in series, which is illustrated by the dashed arrows between the LM- mechanism 410 and the LM+ mechanism 408, and between the LM+ mechanism 408 and the engine valve 404.

[0023] The valve actuation systems 400, 400’ of FIGS. 4 and 5 facilitate the operation of the cylinder 405, and as a result, in a system having a single valve actuation motion source 402, facilitate the operation of the internal combustion engine in a positive power mode, a rest mode, or an auxiliary mode, and provide all valve actuation motions to the engine valves 404. This is further described with reference to the method illustrated in FIG. 14. In block 1402, as described above, the LM+ and LM- mechanisms are disposed in the valve actuation load path. In particular, the LM- mechanism is configured to transmit at least the main valve actuation motion applied thereto in a first default operating state, and to lose the main valve actuation motion and the auxiliary valve actuation motion applied thereto in a first activation state. Additionally, the LM+ mechanism is configured to lose any auxiliary valve actuation motion applied thereto in a second default operating state, and to transmit the auxiliary valve actuation motion in a second activation state, and the LM+ mechanism is in series with the LM- mechanism of the valve actuation load path at least during the second activation state.

[0024] After preparing the valve actuation system in step 1402, the process proceeds to any of blocks 1406-1410, where the engine is operated in a positive power mode, a rest mode, or an auxiliary mode, respectively, based on the control of the operating states of the LM+ and LM- mechanisms. Thus, in block 1406, to operate the engine in the positive power mode, the LM- mechanism is placed in its first default operating state and the LM+ mechanism is placed in its second default operating state. In this mode, the LM+ mechanism does not transmit any auxiliary valve actuation motion, but can transmit any main valve actuation motion transmitted by the LM- mechanism (depending on whether the LM+ mechanism is arranged as in FIG. 4 or FIG. 5). The net effect of this configuration is that only the main valve actuation motion is transmitted to the engine valves, as required for positive power operation.

[0025] In block 1408, to operate the engine in the shutdown mode, the LM - mechanism is placed in its first startup operating state and the lost motion adder mechanism is in its second default operating state. In this mode, the LM - mechanism does not transmit any valve operating motion applied to it. As a result, the corresponding cylinder is shut down as long as the valve operating motion is not transmitted to the engine valve. Considering this operation of the LM - mechanism, the operating state of the LM + - mechanism will not affect the engine valve. However, in the current preferred embodiment, during the shutdown mode operation, the LM + - mechanism is placed in its second default operating state.

[0026] In block 1410, to operate the engine in the auxiliary mode, the LM - mechanism is placed in its first default operating state and the LM + - mechanism is placed in its second startup operating state. In this mode, the LM + - mechanism transmits any auxiliary valve operating motion and any main valve operating motion transmitted by the LM - mechanism. The net effect of this configuration is that both the operating motion of the main valve and the operating motion of the auxiliary valve are transmitted to the engine valve, thereby providing an auxiliary operation provided by a specific auxiliary valve operating motion, such as EEVO, LIVC, compression - release engine brake, etc.

[0027] The operation of the engine between any of the various modes provided in steps 1406 - 1410 can continue as long as the engine is running, as illustrated by block 1412.

[0028] FIG. 6 illustrates a partial cross-sectional view of a valve actuation system 600 according to the embodiment of FIG. 4. In particular, system 600 includes a valve actuation motion source 602 in the form of a cam operably connected to rocker arm 604 at motion receiving end 606 of rocker arm 604. A rocker arm biasing element 620 (e.g., a spring) reacting against a fixed surface 622 may be provided to assist in biasing rocker arm 604 into contact with the valve actuation motion source. As is known in the art, rocker arm 604 reciprocates rotatably about a rocker shaft (not shown), thereby imparting valve actuation motion provided by the valve actuation motion source to valve bridge 610 via motion imparting end 608 of rocker arm 604. Valve bridge 610 is then operably connected to a pair of engine valves 612, 614. As further shown, valve bridge 610 includes an LM-mechanism 616 (locking piston) of the type illustrated and described in FIG. 1 above, while rocker arm 604 includes an LM+ mechanism 618 (actuator) of a type substantially similar to that illustrated and described above in connection with FIG. 2.

[0029] Details of the LM+ mechanism 618 are further illustrated in FIG. 7 along with other components disposed within rocker arm 604. The LM+ mechanism 618 includes an actuator piston 702 attached to a retainer 703 such that the actuator piston 702 is slidably disposed on a lash adjusting screw 704. Further details of the LM+ mechanism 618 are described with reference to FIG. 9 below. As best shown in FIG. 9, the lash adjusting screw 704 is threadedly fastened within an actuator piston bore 710 such that the LM+ mechanism 618 is disposed below a lower portion of the actuator piston bore 710. A lock nut 704 is provided to fix the lash adjusting screw 704 at a desired lash setting during use.

[0030] FIG. 7 also illustrates a reset assembly 712 disposed within a reset assembly bore 724 that includes openings (not shown) in the upper and bottom (not shown) of the rocker arm 604. The reset assembly 712 includes a reset piston 714 slidably disposed within the reset assembly bore 724. A reset piston spring 715 is disposed on the reset piston 714, and the lower end of the reset piston spring 716 is fixed to the reset piston 714 using a c-clip 718 or other suitable component. A washer 720 is disposed on the upper end of the reset piston spring 716. The reset assembly 712 is maintained within the reset assembly bore 724 by a spring clip 722, as is known in the art. As will be described in more detail below with respect to FIGS. 10 and 11, the reset piston spring 716 biases the reset piston 714 from the lower opening of the reset assembly bore 724 such that the reset piston 714 can contact a fixed surface (not shown in FIG. 7). As the rocker arm 604 reciprocates, the reset piston 714 slides within the reset assembly bore 724 in a controllable manner defined by the rotation of the rocker arm 604. In particular, at a desired position of the rocker arm 604, as will be described in more detail below, the reset piston 714 can be configured such that an annular channel 715 formed in the reset piston aligns with a reset passage 802 (FIG. 8) to achieve a reset of the LM+ mechanism 618.

[0031] FIG. 7 further illustrates an upper hydraulic passage 730 formed in a rocker arm 604 that receives a check valve 732. As will be described in more detail below, the upper hydraulic passage 730 provides hydraulic fluid (provided by a suitable supply passage formed in the rocker shaft, not shown) to an actuator piston bore 710 in order to control the operation of the LM+ mechanism 618. A threaded plug 734 or a similar device can be used to ensure a liquid-tight seal on the upper hydraulic passage 730 after installation of the check valve 732. Additionally, for completeness, FIG. 7 also illustrates a rocker arm bushing 740 that can be inserted into a rocker shaft opening 742 and onto the rocker shaft, as is known in the art. Additionally, a cam follower 744 can be attached to a cam follower shaft 746 disposed within a suitable opening 748.

[0032] However, unlike the actuator piston 210 of FIG. 2, the actuator piston 702 of the LM+ mechanism 618, as best illustrated in FIG. 9, includes hydraulic passages 904, 906 that allow hydraulic fluid to be supplied from the actuator piston 702 to the LM- mechanism 616. As shown in FIG. 9, a lower hydraulic passage 908 formed in the rocker arm 604 receives hydraulic fluid from a supply channel within a rocker shaft (not shown) and routes the hydraulic fluid to the lower portion of the actuator piston bore 710. The actuator piston 702 includes an annular channel 910 formed in its sidewall surface that aligns with the hydraulic supply passage 908 throughout the stroke of the actuator piston 702. The annular channel 910 then communicates with a horizontal passage 904 and a vertical passage 906 formed within the actuator piston 702. The vertical passage 906 directs the hydraulic fluid to a swirl 706 having an opening formed therein for passing the hydraulic fluid to the LM- mechanism 616. In this way, the hydraulic fluid can be selectively supplied as a control input to the LM- mechanism 616.

[0033] As described above, and as further shown in FIG. 9, the LM+ mechanism 618 includes a lash adjustment screw 704 that extends into the actuator piston bore 710. The actuator piston spring 918 is disposed between the lash adjustment screw 704 and the actuator piston 702 and abuts against the lower surface of a shoulder 920 formed on the lash adjustment screw 704, thereby biasing the actuator piston 702 out of the actuator piston bore 710. In this embodiment, the actuator piston 702 is fastened via suitable threads to a retainer 703 that engages the upper surface of the lash adjustment screw shoulder 920, thereby restricting the outward stroke of the actuator piston 702.

[0034] FIGS. 8 and 9 further illustrate (in phantom in FIG. 9) an upper hydraulic passage 730 formed in the rocker arm 604 for selectively supplying hydraulic fluid (e.g., high-speed solenoid, not shown) to the actuator piston bore 710 above the actuator piston 702. (Note in FIG. 8 that the various components forming the LM+ mechanism 618 and the reset assembly 712 are not shown for ease of illustration.) A check valve 732 is provided in a widened portion 730' of the upper hydraulic passage 730 to prevent backflow of hydraulic fluid from the actuator piston bore 710 into the supply passage that supplies the upper hydraulic passage 730. In this way, a high-pressure chamber can be formed within the actuator piston bore 710 between the check valve 732 and the actuator piston 702 such that, when there is no reset of the LM+ mechanism 618 as described below, the locked volume of hydraulic fluid maintains the actuator piston 702 in the extended (activated) state.

[0035] As described above in connection with FIG. 3, a valve actuation system in which a single valve actuation motion source provides both primary and secondary valve actuation motions may require the ability to reset to avoid over-extension of the engine valves during the combined secondary and primary valve actuation motions. In the context of the embodiments illustrated in FIGS. 6-11, venting of the locked volume of hydraulic fluid and resetting of the actuator piston 702 is provided through the operation of a reset assembly 712. As best shown in FIG. 8, a reset passage 802 is provided in fluid communication with that portion of the actuator piston bore 710 to form a high pressure chamber having an actuator piston 702 and a reset piston bore 804. The reset piston 714 is, in effect, a spool valve having an end that extends from the bottom of the rocker arm 604 under the bias of a reset piston spring 716. In the embodiments illustrated in FIGS. 10 and 11, the reset piston 714 is of sufficient length and the reset piston spring 716 has sufficient stroke to ensure that the reset piston 714 continuously contacts a fixed contact surface 1002 throughout all positions of the rocker arm 604.

[0036] As shown in FIG. 10, the rocker arm 604 is at the base circle with respect to the cam 602 (i.e., rotated to the maximum towards the cam 602). In this state, and at a relatively low lift (e.g., below the reset height shown in FIG. 3), the annular channel 715 is not aligned with the reset passage 802 such that the outer diameter of the reset piston 714 seals the communication with the reset passage 802, thereby maintaining the volume of fluid (if provided) confined within the actuator piston bore 710 (hidden behind the upper hydraulic passage 730 as shown in FIGS. 10 and 11). The rocker arm 604 rotates at a higher valve lift (e.g., above the reset height shown in FIG. 3) as shown in FIG. 11, so that the reset piston 714 pivots about the contact point with the fixed surface 1002 and slides with respect to the reset piston bore 804 such that the annular channel 715 aligns with the reset passage 802, thereby allowing the trapped hydraulic fluid to flow through the annular channel 715 into the radial hole 1004 formed in the reset piston 714 and vent through the upper part of the axial passage 1006 (shown in phantom) formed in the reset piston 714. When the rocker arm 604 rotates again after a high lift event, as in FIG. 10, the reset piston 714 translates within its bore 804 and seals the reset passage 802 again, thereby allowing refilling of the actuator piston bore 710.

[0037] As described above, the reset assembly 712 illustrated in FIGS. 6 - 11 is configured to maintain constant contact with the fixed contact surface 1002. However, it is understood that this is not a requirement. For example, the reset assembly can alternatively comprise a poppet valve that contacts the fixed surface only when the required reset height is achieved.

[0038] As described above, the rocker arm biasing element 620 may be provided to assist in biasing the rocker arm 604 into contact with the cam 602. A feature of the disclosed system 600 is that neither the rocker arm biasing element 620 nor the actuator piston spring 918 is individually configured to provide sufficient force to bias the rocker arm 604 into contact with the cam 602 through substantially all operating conditions. However, in this embodiment, the rocker arm biasing element 620 and the actuator piston spring 918 are selected to function in combination for this purpose through substantially all operating conditions of the rocker arm 604. For example, to help bias the rocker arm 604 toward the cam 602, the actuator piston spring 918 provides high force only during relatively low lift valve actuation motions (e.g., EEVO, LIVC, etc.), where most is needed due to potential high speed operation. If uncontrolled, the biasing force applied by the actuator piston spring 918 can press the actuator piston 702 against the LM - mechanism 616 with significant force. If the LM - mechanism 616 is a mechanical locking mechanism as described with reference to FIG. 1, such force is strong enough to impede the ability of the locking element 180 to extend and retract, thereby preventing locking and unlocking of the LM - mechanism 616. The movement limitation imposed by the lash adjustment screw shoulder 920 of the actuator piston 702 prevents such excessive loading on the LM - mechanism 616, thereby maintaining the lash space normally provided within the LM - mechanism 616 and allowing the locking element 180 to freely extend / retract as needed.

[0039] Additionally, although the extension of the actuator piston 702 by the actuator piston spring 918 is relatively small, it still reduces the range of stress that the outer plunger spring 746 has to withstand. Next, the actuator piston spring 918 can be a high-force, low-travel spring that provides the high forces particularly required for low-lift, potentially high-speed valve actuation motions. This load sharing by the actuator piston spring 918 and the outer plunger spring 746 can also reduce the need for the rocker arm biasing element 620 to provide a high preload, allowing the design of the rocker arm biasing element 620 to focus on the slower and higher-lift portions for the main valve actuation motions that occur during resting-state operation, which are less stringent design constraints.

[0040] FIG. 12 illustrates a partial cross-sectional view of a valve actuation system 1200 according to the embodiment of FIG. 5. In this system 600, the valve actuation motion source includes a cam (not shown) operably connected to the motion receiving end 1206 of a rocker arm 1204 via a push tube 1202, and an intervening LM-mechanism 1216 of the type illustrated and described in FIG. 1 above. Similar to the embodiments illustrated in FIGS. 6-11, the rocker arm 1204 rotates and reciprocates about a rocker shaft (not shown), thereby imparting valve actuation motion provided by the valve actuation motion source to a valve bridge 1210 via the motion imparting end 1208 of the rocker arm 1204. Next, the valve bridge 1210 is operably connected to a pair of engine valves 1212, 1214. As further shown, the rocker arm 1204 includes an LM+ mechanism 1218 of substantially the same type as that illustrated and described in connection with FIG. 2. In this case, hydraulic fluid is provided to the LM-mechanism 1216 via suitable passages formed in the rocker shaft and the rocker arm 1204 and the ball joint 1220. Similarly, hydraulic fluid is provided to the LM+ mechanism 1218 via suitable passages formed in the rocker shaft and the rocker arm 1204. However, in this implementation, the check valve 732 of the preceding embodiment is replaced by a control valve 1222 to establish a hydraulic lock necessary to maintain the actuator piston in the extended state. The embodiment of FIG. 12 is further characterized by the arrangement of the LM+ mechanism 1218 that interacts with only a single engine valve 1214 via a suitable bridge pin 1224.

[0041] In this embodiment, the LM-mechanism 1216 includes a relatively strong spring for biasing the outer plunger of the locking mechanism outwardly relative to the push rod 1202 such that the push rod 1202 is biased into contact with the cam and the rocker arm is biased in the direction of the engine valves 1212, 1214. In this implementation, the outer plunger of the LM-mechanism 1216 is not limited during engine operation (as opposed to the engine assembly), but imposing a movement limit on the LM-mechanism 1216 facilitates assembly.

[0042] Considering the configuration of the LM+ mechanism 1218, particularly the actuator piston with an inward spring, when the LM+ mechanism 1218 is in its default state, a gap is provided between the actuator piston and the bridge pin. As a result, during this default state, the LM+ mechanism 1218 is not in series along the motion load path having the LM- mechanism 1216 as described above in relation to FIG. 5. Further, despite the existence of the gap during the default state, the actuator piston cannot fully extend considering the strength of the outer plunger piston spring as described above. In this case, the actuator piston cannot fully extend until the main motion valve event occurs, thereby creating a sufficient gap between the actuator piston and the bridge pin 1224 to allow full extension. However, when in the extended (activated) state, the actuator piston not only transmits the auxiliary valve operating motion applied thereto but also transmits the main valve operating motion applied to its corresponding engine valve 1214. In this case, the LM+ mechanism 1218 is placed in series with the LM- mechanism 1216 during the activated state of the actuator piston as described above in relation to FIG. 5.

[0043] FIG. 13 illustrates a partial cross-sectional view of a valve operating system 1300 according to the embodiment of FIG. 5. In particular, the embodiment illustrated in FIG. 13 is substantially the same as the embodiment of FIG. 12 except that the spherical joint 1220 is replaced with an outwardly biased and movement-limited slide pin 1320. In this case, the outer plunger spring of the LM- mechanism 1216 is preferably designed with a low preload during zero or low valve lift (e.g., on the base circle) and has a spring rate necessary to obtain the peak force for controlling the entire motion of the rocker arm 1204 over the main valve operating motion during the rest mode operation.

[0044] On the other hand, the slide pin spring 1322 used to bias the slide pin 1320 outward is configured with a relatively high preload and a short stroke (substantially the same as the actuator piston spring 918 discussed above). Since the slide piston 1320 can slide within its bore, the slide piston 1320 aligns the fluid supply passage with the annular channel 1334 over the entire stroke of the slide piston 1320 to ensure continuous fluid communication between the rocker arm 1204 and the LM - mechanism 1216, and includes the annular channel 1334 and the radial opening 1336 aligned therewith. Additionally, the stroke adjustment screw 1338 functions to limit the movement of the slide pin 1320 from its bore towards the LM - mechanism 1216. As described with respect to the movement limiting ability applied to the actuator piston 702 above, the stroke adjustment screw 1338 prevents the full force of the slide pin spring 1322 from being applied to the LM - mechanism 1216, which would otherwise be overloaded and potentially interfere with its operation. By appropriately selecting the stroke provided by the stroke adjustment screw 1338, i.e., equal to the motion that must be lost by the LM + mechanism during its default operating state, the lash provided to the locking element within the LM - mechanism 1216 can be selected to ensure its proper operation as described above. In practice, the assembly of the slide pin 1320, the slide pin spring 1322, and the stroke adjustment screw 1338 constitute part of the LM + mechanism in this embodiment.

[0045] As described above, various specific combinations of outward (extended) and inward spring-loaded (stored) elements within the LM+ and LM- mechanisms can be provided with movement restrictions as necessary. More generally, in one implementation, the LM- mechanism (more specifically, an element or its component) can be biased to an extended position, and the LM+ mechanism (again, more specifically, an element or its component) can be biased to a stored position. In this case, the extended position of the LM- mechanism can be movement-restricted. In another implementation of any given embodiment, the LM- mechanism can be biased to an extended position by a first force, and the LM+ mechanism can also be biased to an extended position by a second force. In this case, the first biasing force is preferably greater than the second biasing force. Additionally, again, the extended position of the LM- mechanism can be movement-restricted. In yet another implementation, the LM- mechanism can be biased to an extended position, and the LM+ mechanism can also be biased to an extended position. In this case, however, the extended position of the LM+ mechanism is movement-restricted. An advantage that may limit the movement of the LM+ mechanism in this implementation is to enable zero load on the valve train on the cam base circle to reduce bushing wear.

[0046] As described above with respect to FIG. 4 and as shown with respect to FIG. 15 where like reference numerals refer to like elements as compared to FIG. 4, a system 1500 can be provided where the LM- mechanism 410' is disposed within the valve actuation motion path 406 and is parallel to the LM+ mechanism 408'. More specifically, the LM+ mechanism 408' shown in FIG. 15 is parallel to the LM- mechanism 410' during the activation state of the LM+ mechanism 408' (as illustrated by the dashed line between the LM+ mechanism 408' and the engine valve 404), but is not parallel during the default operating state of the LM+ mechanism 408'. In this way, the LM+ mechanism 408' only serves to transmit the auxiliary valve actuation motion received by the LM+ mechanism 408', and otherwise is not involved in transmitting the main valve actuation motion along the valve actuation load path 406.

[0047] Specifically, when the LM+ mechanism 408’ is in its default operating state, the LM+ mechanism 408’ is configured to lose any auxiliary valve actuation motion applied thereto by the valve actuation motion source 402. On the other hand, when the LM+ mechanism 408’ is in its activation operating state, i.e., when it is controlled to transmit any auxiliary valve actuation motion applied thereto, the LM+ mechanism 408’ is involved in the transmission of the auxiliary valve actuation motion received from the valve actuation source 402. In other words, the ability of the LM+ mechanism 408’ to transmit the auxiliary valve actuation motion is independent of the operation of the LM- mechanism 410’. Configured in this way, the valve actuation system 1500 facilitates the operation of the cylinder 405, and as a result, in a system having a single valve actuation motion source 102, facilitates the operation of the internal combustion engine in the positive power mode, the rest mode, or the auxiliary mode (e.g., engine brake), and provides all valve actuation motions to the engine valve 404. That is, the system 1500 can be implemented in the manner illustrated and described above with reference to FIG. 14. However, in this case, as described in more detail below, the provision of the LM- mechanism and the LM+ mechanism at block 1402 is such that the LM- mechanism and the LM+ mechanism are in parallel with each other within the valve actuation load path and occur within the valve bridge and the rocker arm, respectively.

[0048] Figures 16 to 23 illustrate implementation forms of the valve operating systems 1600 and 2000 according to the embodiment of FIG. 15. Here, referring to FIG. 16, a first implementation form of the valve operating system 1600 includes a rocker arm 1602 operably connected to a valve bridge 1604 via a slide e-foot assembly 1640 and an LM-mechanism 1670 on one hand and via an LM+ mechanism 1620 on the other hand. As illustrated, the LM-mechanism 1670 is disposed within the valve bridge 1604 in substantially the same manner as the embodiment illustrated in FIG. 6. Similar to its preceding embodiment, the LM-mechanism 1670 is of the type illustrated and described in FIG. 1 above. As further shown in this embodiment, the LM+ mechanism 1620 is disposed within the rocker arm 1602 and is a certain type of hydraulically controlled actuator in which an actuator piston 1622 is biased to a retracted position, in contrast to the embodiment of the outwardly biased actuator described in connection with FIG. 2. Thus, according to FIG. 15, the LM+ mechanism 1620 is disposed in parallel with the LM-mechanism 1670 within the valve operating load path established by the rocker arm 1602 and the valve bridge 1604.

[0049] As is known in the art, valve bridge 1604 is operably connected to at least two engine valves 1606, 1612, which are then biased to a closed position and biased to contact valve bridge 1604 through the action of respective valve springs 1608, 1614 and spring retainers 1610, 1616. As further shown, LM - mechanism 1670 is disposed within a central bore defined within valve bridge 1604 and includes an outer plunger 1672 and an inner plunger 1674. A locking element in the form of a wedge 1676 is provided, which is configured to engage an annular outer recess 1678 formed in the surface defining the central bore. Outer plunger 1672 is biased by outer plunger spring 1680 to contact slide e foot assembly 1640 from within the bore. As described above, when no hydraulic control is applied to inner plunger 1674 (via slide e foot assembly 1640), wedge 1676 extends from an opening formed in outer plunger 1672, thereby engaging outer recess 1678 and effectively locking outer plunger 1672 in a predetermined position relative to valve bridge 1604. In this state, any valve actuation motion applied to valve bridge 1604 via outer plunger 1672 is transmitted to valve bridge 1604 and ultimately to engine valves 1606, 1612. However, as further described above, providing sufficiently pressurized hydraulic fluid to the upper portion of inner plunger 1674 allows wedge 1676 to be retracted and disengaged from outer recess 1678, thereby effectively releasing the lock of outer plunger 1672 relative to valve bridge 1604 and allowing outer plunger 1672 to freely slide within its bore under the bias provided by outer plunger spring 1680 towards the rocker arm. In this state, any valve actuation motion applied to outer plunger 1672 causes outer plunger 1672 to reciprocate within its bore.Thus, assuming that the movement of the outer plunger 1672 within the bore is greater than the maximum extent of any applied valve actuation motion, such valve actuation motion is not transmitted to the engine valves 1606, 1612 and is effectively lost such that the corresponding cylinder is deactivated.

[0050] The illustrated LM+ mechanism 1620 includes an actuator piston 1622 slidably disposed in a first bore 1624 formed in a rocker arm 1602, where the actuator piston 1622 is inserted into the first bore 1624 at its open end. As illustrated, the first bore 1624 is configured such that the LM+ mechanism 1620 is aligned with a first engine valve 1612 of at least two engine valves 1606, 1612. A lash adjusting screw 1626 also extends into the first bore 1624 from an opening formed in an otherwise closed end of the first bore 1624 and further into an internal space formed in the actuator piston 1622. The lash adjusting screw 1626 includes a shoulder or flange 1630 configured to radially extend at its distal end and support one end of an actuator spring 1632. Next, the other end of the actuator spring 1632 abuts a spring retainer 1634 that is fixedly maintained in a predetermined position relative to the actuator piston 1622 by a fastener such as a snap ring 1636. In this way, the actuator piston 1622 is biased into the first bore 1624 by the actuator spring 1632 within a range allowed by the actuator piston 1622 abutting the lower end (adjacent to the shoulder 1630) of the lash adjusting screw 1626. The threads formed at the interface between the lash adjusting screw 1626 and the rocker arm 1602 allow the lash adjusting screw 1626 to be adjusted so as to select, as desired, the distance (lash) between the actuator piston 1622 and a bridge pin 1619 (described in more detail below) when the actuator piston 1622 is in its fully retracted state. As is known in the art, a first lock nut 1628 may be used to hold the lash adjusting screw 1626 in its desired position.

[0051] A hydraulic passage (not shown) formed within the rocker arm 1602 may be provided according to known techniques to supply hydraulic fluid to a control valve 1623 also disposed within the rocker arm 1602. Also, according to known techniques, the control valve 1623 supplies hydraulic fluid to the first bore 1624 such that the actuator piston 1622 slides out of the first bore 1624 against the biasing force of the actuator spring 1632 when the actuator piston 1622 is free to slide out of the first bore 1624. Thus, the locked fluid volume established within the first bore 1624 by the control valve 1623 firmly maintains the actuator piston 1622 in its extended position until hydraulic fluid is no longer supplied to the control valve 1623, thereby allowing the locked fluid volume to flow out and enabling the actuator spring 1632 to bias the actuator piston 1622 back into the first bore 1624 again.

[0052] The implementation illustrated in FIG. 16 is characterized in particular by providing a slide e-foot assembly 1640 (related to the implementation illustrated in FIGS. 20 - 23). As shown, the slide e-foot assembly 1640 comprises a housing 1642 mounted in a second bore 1644 formed within the rocker arm 1602. For example, the outer surface of the housing 1642 may have a threaded engagement with the inner surface of the second bore 1644 such that the vertical positioning of the housing 1642 within the second bore 1644 (and as a result, the positioning of the slide e-foot assembly 1640 relative to the LM-mechanism 1670) can be selected through rotation of the housing 1642. Such vertical alignment may be maintained by engaging a second lock nut 1643 with the threaded surface of the housing 1642. As illustrated, the second bore 1646 is configured such that the slide e-foot assembly 1640 is aligned with the center of the LM-mechanism 1670, i.e., the valve bridge 1604.

[0053] The housing 1642 includes an internal bore 1646 having an opening end that faces the valve bridge 1604 when deployed within the second bore 1644. A slide member or piston 1648 is disposed within the internal bore 1646 of the housing 1642 and is biased outward of the internal bore 1646 by a slide member spring 1650 interposed between the housing 1642 and the slide member 1648. A shoulder or flange 1662 is formed at the distal end of the slide member 1648 such that solid contact between the shoulder 1662 and the housing 1642 restricts movement of the slide member 1648 within the internal bore 1646. An inner annular channel 1656 is formed along the outer surface of the slide member 1648 and extends longitudinally, and a snap ring 1660 or the like can be deployed within the inner annular channel 1656 and between the inner surface of the housing 1642 and the slide member 1648. In this way, the snap ring 1660 restricts movement of the slide member 1648 from the internal bore 1646 according to the longitudinal extent of the inner annular channel 1656. Configured in this way, when no canceling force is applied to the slide member 1648, the slide member 1648 is biased by the slide member spring 1650 from the internal bore 1646, thereby establishing a lash space L between the shoulder 1662 of the slide member 1648 and the housing 1642.

[0054] As further shown in FIG. 16, the housing 1642 includes an outer annular channel 1652 that extends longitudinally along the outer surface of the housing 1642. The outer annular channel 1652 is aligned with a hydraulic passage (not shown) formed within the rocker arm 1602 and provides a selectively controlled or switched supply of hydraulic fluid, according to known techniques, for example via a rocker shaft and a solenoid. The housing further includes at least one opening 1654 formed in the sidewall of the housing 1642 and aligned with the outer annular channel 1652 such that fluid communication is provided between the outer annular channel 1652 and the internal bore 1646 of the housing 1642. Next, the slide member 1648 includes a central longitudinal bore 1664 that extends through the spherical or ball-shaped end 1665 of the slide member 1648. The slide member 1648 also includes a transverse bore 1658 that establishes fluid communication between the inner annular channel 1656 of the slide member 1648 and the longitudinal bore 1646. Finally, the slide member 1648 has a swivel or e-foot 1666 attached to the spherical end 1665 of the slide member 1648 according to known techniques. The e-foot 1666 includes an opening that allows continuous fluid communication with the longitudinal bore 1664 through the e-foot 1666 despite movement of the e-foot 1666 relative to the spherical end 1665.

[0055] Thus configured, when the inner annular channel 1656 is longitudinally aligned with the opening 1654, the hydraulic fluid selectively provided to the outer annular channel 1652 can flow into the inner annular channel 1656, then into the transverse bore 1658 and the longitudinal bore 1664, and then out through the opening formed in the e-foot 1664.

[0056] FIG. 16 illustrates the operating conditions where both the LM - mechanism 1670 and the LM + mechanism are in their default operating states as described above. Additionally, FIG. 16 illustrates the condition where the rocker arm 1602 is controlled according to a sub - base circle region of a single cam (not shown), i.e., when neither the main valve actuation motion nor the auxiliary valve actuation motion is applied to the rocker arm 1602. Additionally, as is known in the art, such a sub - base region results in the maximum displacement of the rocker arm 1602 away from the valve bridge 1604. As shown in FIG. 16, during this operating condition, the slide member 1648 is capable of extending from the inner bore 1646 to its maximum extent. Preferably, the configuration of the slide member 1648, the outer plunger 1672, and their respective biasing springs 1650, 1680 is such that contact between the lower surface of the e - foot 1666 and the upper surface of the outer plunger 1672 is maintained even during this maximum displacement of the rocker arm 1602, thereby enabling fluid communication between the slide member 1648 and the inner plunger 1674. In the presently preferred embodiment, the slide member spring 1650 is selected to provide sufficient force to bias the rocker arm 1602 into contact with a single cam throughout all operating conditions of the valve actuation system 1600.

[0057] Referring now to FIGS. 17 - 19, various operating conditions of the valve actuation system 1600 are further illustrated and described. For all the operating conditions illustrated in FIGS. 17 - 19, it should be noted that the lash L between the slide member 1648 and the housing 1642 is fully absorbed, i.e., the slide member 1648 is in solid contact with the lower surface of the housing 1642 in response to the applied valve actuation motion. Prior to such full absorption of the lash space L, any valve actuation motion applied to the housing 1642 is lost until the slide member 1648 comes into solid contact with the lower surface of the housing 1642. As a result, as is known in the art, if the lash L is set to the same magnitude as any auxiliary valve actuation motion provided below the base circle lift of at least a single cam, any valve actuation lift below the base circle lift is lost through the motion of the slide member 1648 relative to this housing 1642.

[0058] FIG. 17 illustrates the same operating conditions as the valve actuation system 1600 illustrated in FIG. 16 (i.e., both the LM - mechanism 1670 and the LM + mechanism are in their default operating states), but with the rocker arm 1602 being controlled according to the maximum lift region of a single cam, i.e., at the peak of the main valve actuation motion applied to the rocker arm 1602. As a result, as shown, the engine valves 1606, 1612 are lifted from their respective valve seats 1706, 1712 to the maximum extent.

[0059] FIG. 18 illustrates the operating conditions of the valve actuation system 1600 where the LM - mechanism 1670 is in its default operating state and the LM + mechanism 1620 is in its starting state. As shown and as described above, this results in the extension of the actuator piston 1622 to its maximum extent (which can be achieved prior to contact of the actuator piston 1622 with the bridge pin 1619), while the LM - mechanism 1670 remains in its locked state. As further shown in FIG. 18, the rocker arm 1602 is controlled according to the peak of the auxiliary valve actuation motion, such as the maximum auxiliary lift region of a single cam, i.e., the compression release valve actuation motion applied to the rocker arm 1602. Assuming that the peak of the auxiliary valve actuation motion is equal to the base circle defined by a single cam, the slide member 1648 absorbs the lash space L but does not apply further valve actuation motion to the valve bridge 1604. On the other hand, the extension of the actuator piston 1622 to its maximum extent causes, as shown, the peak auxiliary motion lift to lift the first engine valve 1612 from the valve seat 1712, while the other engine valve 1606 remains within its valve seat 1706 as the actuator piston 1622 is brought into contact with the bridge pin 1619.

[0060] Figure 19 illustrates the operating conditions of the valve actuation system 1600 where the LM - mechanism 1670 is in its startup operating state and the LM + - mechanism 1620 is in its default state. As shown and as described above, this results in the retraction of the actuator piston 1622, and the LM - mechanism 1670 is placed in its unlocked state. As further shown in Figure 19, similar to Figure 17, the rocker arm 1602 is controlled according to the maximum lift region of a single cam, i.e., the peak of the main valve actuation motion applied to the rocker arm 1602. Since the LM - mechanism 1670 is in its startup operating state, the outer plunger 1672 is able to reciprocate with the central bore of the valve bridge 1604 such that no valve actuation motion is applied to the valve bridge 1604. Additionally, since the actuator piston 1622 is retracted, no auxiliary valve actuation motion is applied to the first engine valve 1612, and as a result, the actuator piston 1622 cannot contact the bridge pin 1619. Desired operating states such as cylinder deactivation can be achieved as long as valve actuation motion is not applied to the engine valves 1606, 1612.

[0061] Referring now to FIG. 20, a second implementation of the valve actuation system 2000 includes a rocker arm 2002 operatively connected to the valve bridge 2004 via a fixed e-foot assembly 2040 and an LM-mechanism 2070 on one hand and via an LM+ mechanism 1620 on the other hand. Substantially similar to the system 1600 of FIG. 16, the LM-mechanism 2070 is disposed on the valve bridge 1604 in substantially the same manner as the embodiment illustrated in FIG. 6. Similar to its preceding embodiment, the LM-mechanism 1670 is of the type illustrated and described in FIG. 1 above. The LM+ mechanism 1620 is also disposed on the rocker arm 1602 and is of the type described above in connection with FIGS. 16-19. Again, according to FIG. 15, the LM+ mechanism 1620 is disposed in parallel with the LM-mechanism 2070 within the valve actuation load path established by the rocker arm 2002 and the valve bridge 2004. The difference between the implementations of FIGS. 16-19 and the implementations of FIGS. 20-23 is found in the specific configuration of the LM-mechanism 2070 and the fixed e-foot assembly 2040 (relative to the slide e-foot assembly 1640).

[0062] More specifically, the fixed e-foot assembly 2040 includes a second lash adjustment screw 2042 threadedly mounted within a second bore 2043 formed in the rocker arm 2002. Similar to the slide member 1642 of the embodiment of FIG. 16, the second bore 2043 and the second lash adjustment screw 2042 are configured to be aligned with the LM-mechanism 2070. As is known in the art, the vertical positioning of the second lash adjustment screw 2042 can be established by adjusting the screw engagement with the second bore 2043 and can be maintained through the use of a second lock nut 2044. Similar to the slide member 1642, the second lash adjustment screw 2042 includes a transverse bore and a longitudinal bore formed therein, as well as a spherical end and an e-foot in fluid communication with the longitudinal bore. In this way, the second lash adjustment screw 2042 can selectively supply hydraulic oil controlled by the LM-mechanism 2070 (as in the embodiments of FIGS. 16-19).

[0063] The e-foot assembly 2040 is "fixed" in the sense that the slide member 1642 is replaced with a substantially fixed second lash adjusting screw 2042, so the need for a lash space within the system 2000 is instead provided by the LM - mechanism 2070. More specifically, the annular outer recess 1678 in the embodiment of FIG. 16 is configured to have a longitudinal extent substantially similar to the thickness of the lock element 1676, whereas the annular outer recess 2078 in the embodiment of FIG. 20 is configured to have a longitudinal extent that allows a lash space L' to be established between the lower surface of the annular outer recess 2078 and the lower surface of the lock element 1676. Additionally, in this case, the outer plunger spring 2080 is selected not only to bias the outer plunger 1672 out of the central bore of the valve bridge, but also to provide sufficient force to bias the rocker arm 2002 to re - contact a single cam (through contact between the fixed e - foot assembly 2040 and the outer plunger 1672) throughout all operating conditions of the valve actuation system 2000.

[0064] Referring now to FIGS. 21 - 23, various operating conditions of the valve actuation system 2000 are further illustrated and described. Again, at all operating conditions illustrated in FIGS. 21 - 23, it will be noted that the lash L' between the lock element 1676 and the annular outer recess 2078 is fully absorbed, i.e., the lower surface of the lock element 1676 makes solid contact with the lower surface of the annular outer recess 2078 in response to the applied valve actuation motion. Prior to such full absorption of the lash space L', any valve actuation motion applied to the outer plunger 1672 is lost until the lock element 1676 comes into solid contact with the annular outer recess 2078. As a result, as is known in the art, if the lash L' is set to the same magnitude as any auxiliary valve actuation motion provided below the base circle lift of at least a single cam, any valve actuation lift below the base circle lift is lost through the operation of this lock element 1676 and the annular outer recess 2078.

[0065] Figure 21 shows the same operating conditions as the valve operating system 2000 illustrated in Figure 20 (i.e., both the LM - mechanism 2070 and the LM+ - mechanism 1620 are in their default operating states), but with the rocker arm 2002 being controlled according to the maximum lift region of a single cam, i.e., at the peak of the main valve operating motion applied to the rocker arm 2002. As a result, as shown, the engine valves 1606, 1612 are lifted from their respective valve seats 1706, 1712 to the maximum extent.

[0066] Figure 22 illustrates the operating conditions of the valve operating system 2000 where the LM - mechanism 2070 is in its default operating state and the LM+ - mechanism 1620 is in its activation state. As shown, and as described above, this results in the extension of the actuator piston 1622 to its maximum extent (which can be achieved prior to contact of the actuator piston 1622 with the bridge pin 1619), but the LM - mechanism 2070 remains in its locked state. As further shown in Figure 22, the rocker arm 2002 is controlled according to the maximum auxiliary lift region of a single cam, i.e., at the peak of an auxiliary valve operating motion such as a compression release valve operating motion applied to the rocker arm 2002. Assuming that the peak of the auxiliary valve operating motion is equal to the base circle defined by a single cam, the annular outer depression 2078 absorbs the lash space L’, but does not apply further valve operating motion to the valve bridge 2004. On the other hand, the extension of the actuator piston 1622 to its maximum extent causes, as shown, the peak auxiliary motion lift to lift the first engine valve 1612 from the valve seat 1712, while the other engine valve 1606 remains within its valve seat 1706 as the actuator piston 1622 is brought into contact with the bridge pin 1619.

[0067] FIG. 23 illustrates the operating conditions of the valve actuation system 2000 where the LM - mechanism 2070 is in its startup operating state and the LM+ mechanism 1620 is in its default state. As shown and as described above, this results in the retraction of the actuator piston 1622, and the LM - mechanism 2070 is placed in its unlocked state. As further shown in FIG. 23, similar to FIG. 21, the rocker arm 2002 is controlled according to the maximum lift region of a single cam, i.e., the peak of the main valve actuation motion applied to the rocker arm 2002. Since the LM - mechanism 2070 is in its startup operating state, the outer plunger 1672 can reciprocate with the central bore of the valve bridge 2004 such that no valve actuation motion is applied to the valve bridge 2004. Additionally, since the actuator piston 1622 is retracted, no auxiliary valve actuation motion is applied to the first engine valve 1612, and as a result, the actuator piston 1622 cannot contact the bridge pin 1619. As long as valve actuation motion is not applied to the engine valves 1606, 1612, desired operating states such as cylinder deactivation can be achieved.

[0068] While various embodiments according to the present disclosure have been described in conjunction with their specific implementations, it will be apparent to those skilled in the art that numerous alternative, modified, and variant forms are possible. In particular, it is understood that the various embodiments described herein can be applied to valve actuation systems having various types of valve train components. For example, as is known in the art, valve train components such as rocker arms can be used to effect a "reset" in which auxiliary valve actuation motion is lost or absorbed by controlling the lost motion mechanism to be reset to a motion absorbing state prior to or during the generation of the primary event valve actuation motion. Accordingly, it is understood that the valve actuation system according to the present disclosure can be implemented using a reset rocker arm (i.e., one that can reset its motion), or a non-resetting rocker arm (i.e., one that cannot reset its motion). Thus, the preferred embodiments of the invention described herein are intended to be illustrative and not limiting, so long as their variations are within the scope of the appended claims and their equivalents.

Claims

Claim 1 An internal combustion engine, the internal combustion engine comprising a cylinder, at least two engine valves associated with the cylinder, and a valve operating load path, the valve operating load path comprising a rocker arm and a valve bridge operably connected to the at least two engine valves, a valve operating system for use in an internal combustion engine, the valve operating system being configured to provide a main valve operating motion and an auxiliary valve operating motion to operate the at least two engine valves via the valve operating load path, a single cam disposed within the valve bridge and configured to transmit at least the main valve operating motion in a first default operating state and configured to lose the main valve operating motion and the auxiliary valve operating motion in a first activation state, a lost motion subtraction mechanism disposed within the rocker arm and configured to lose the auxiliary valve operating motion in a second default operating state and configured to transmit the auxiliary valve operating motion in a second activation state, a lost motion addition mechanism disposed in parallel with the lost motion subtraction mechanism in the valve operating load path at least during the second activation state, the valve operating system comprising the lost motion addition mechanism. Claim 2 using the lost motion subtraction mechanism and the lost motion addition mechanism to operate the internal combustion engine in a positive power mode in which the lost motion subtraction mechanism is in the first default operating state and the lost motion addition mechanism is in the second default operating state, or a rest mode in which the lost motion subtraction mechanism is in a first activation operating state and the lost motion addition mechanism is in the second default operating state, or an auxiliary mode in which the lost motion subtraction mechanism is in the first default operating state and the lost motion addition mechanism is in a second activation operating state, the valve operating system according to claim 1, further comprising an engine controller configured to operate in this way. Claim 3 The valve actuation system according to claim 1, wherein the auxiliary valve actuation motion is at least one of an early exhaust valve opening valve actuation motion, a late intake valve closing valve actuation motion, or an engine brake valve actuation motion.

4. The valve actuation system according to claim 1, wherein the lost motion subtraction mechanism is a hydraulically controlled mechanical locking mechanism.

5. The valve actuation system according to claim 1, wherein the lost motion addition mechanism is a hydraulically controlled actuator.

6. The valve actuation system according to claim 5, wherein the lost motion addition mechanism further comprises a hydraulically controlled check valve that provides hydraulic fluid to the hydraulically controlled actuator.

7. The valve actuation system according to claim 5, wherein the hydraulically controlled actuator is aligned with a first engine valve of the at least two engine valves.

8. The valve actuation system according to claim 1, further comprising a biasing component configured to bias the rocker arm to contact the single cam.

9. The valve actuation system according to claim 8, wherein the biasing component includes a spring operably connected to the rocker arm.

10. The valve actuation system according to claim 8, wherein the biasing component includes a spring disposed within the lost motion subtraction mechanism.

11. A slide pin is disposed within the rocker arm and contacts the lost motion subtraction mechanism. The valve actuation system according to claim 8, wherein the biasing component includes a spring that biases the slide pin to contact the lost motion subtraction mechanism.

12. A method of operating an internal combustion engine, the internal combustion engine comprising a cylinder and at least two engine valves associated with the cylinder, and further comprising a single cam, the single cam being configured to provide a main valve actuation motion and an auxiliary valve actuation motion to operate the at least two engine valves via a valve actuation load path including a rocker arm and a valve bridge, the method comprising: Providing a lost motion subtraction mechanism disposed within the valve bridge and configured to transmit at least the main valve operating motion in a first default operating state and to lose the main valve operating motion and the auxiliary valve operating motion in a first activation state; Providing a lost motion addition mechanism disposed within the rocker arm and configured to lose the auxiliary valve operating motion in a second default operating state and to transmit the auxiliary valve operating motion in a second activation state, the lost motion addition mechanism being disposed in parallel with the lost motion subtraction mechanism in the valve operating load path at least during the second activation state; Operating the internal combustion engine In a positive power mode in which the lost motion subtraction mechanism is in the first default operating state and the lost motion addition mechanism is in the second default operating state, or In a rest mode in which the lost motion subtraction mechanism is in a first activation operating state and the lost motion addition mechanism is in the second default operating state, or In an auxiliary mode in which the lost motion subtraction mechanism is in the first default operating state and the lost motion addition mechanism is in a second activation operating state, the method comprising.

Images