Integrated rocker arm brake for actuating individual engine valves with a reset plunger

Abstract

A rocker arm includes a biasing contact surface configured to receive a force to bias the rocker arm toward a first engine valve. An actuator piston is slidably disposed in a vertical bore of the rocker arm, wherein the actuator piston and the vertical bore are configured to align with the first engine valve. A hydraulic chamber is in fluid communication with the vertical bore, and a checking element is in fluid communication with the hydraulic chamber and configured to allow unidirectional hydraulic fluid inflow into the hydraulic chamber. A reset plunger is sealingly engaged with a reset plunger bore in fluid communication with the hydraulic chamber. The reset plunger has an end extending out of the rocker arm and configured to contact a reaction surface, thereby interrupting the sealing engagement of the reset plunger and allowing hydraulic fluid to drain from the hydraulic chamber.

Description

Technical Field

[0001] This disclosure relates in general to valve actuation systems for actuating engine valves in internal combustion engines, and more particularly to an integrated rocker arm brake having a reset plunger for actuating a single engine valve. Background Technology

[0002] In the field of internal combustion engines, compression-release engine braking is typically achieved using a dedicated compression-release rocker arm, which is separate from the exhaust rocker arm used to transmit the main event valve actuation motion (i.e., those valve actuations typically used to support positive power generation). Recent developments include so-called integrated rocker arm brakes (IRBs), in which the compression-release rocker arm and exhaust rocker arm are combined into a single rocker arm to save costs and provide more compact valve mechanism hardware.

[0003] As is known in the art, and referenced Figure 1 The IRB 100 typically includes a nose (or motion-granting end) of a rocker arm and a selectable actuator 106 configured to transfer primary event valve actuation motion to a pair of engine valves 104 via a valve bridge 102. The selectable actuator is configured to transmit engine brake valve actuation motion to only one engine valve (engine brake valve) 104b via a bridge pin 108 in the valve bridge 102. A single valve actuation motion source 110, such as a cam, is provided, including a convex angle for both primary event valve actuation and engine brake valve actuation (or other auxiliary valve actuation). Figure 1 As further shown, in a typical IRB configuration, control of actuator 106 is provided by an optional hydraulic fluid supply 112, which is operated to supply hydraulic fluid to control valve 114. When no hydraulic fluid is supplied to control valve 114, the actuator piston of actuator 106 remains in a retracted or compliant state, preventing actuator 106 from transmitting valve actuation to bridge pin 108 and engine brake valve 104b. On the other hand, when hydraulic fluid is supplied to control valve 114, hydraulic fluid is subsequently supplied to high-pressure chamber 116, which is in fluid communication with the actuator piston of actuator 106. Control valve 114 also serves to check the hydraulic fluid in high-pressure chamber 116, thereby maintaining hydraulic lock-in of the fluid in high-pressure chamber 116. This keeps the actuator piston in an extended state throughout the engine brake valve actuation movement, thereby transmitting such valve actuation movement to engine brake valve 104b via bridge pin 108.

[0004] The IRB valve mechanism does indeed present several issues regarding valve-piston contact and seat speed.

[0005] Regarding the former, if the actuator piston remains in its extended state during the main event valve actuation, the engine valve 104 (more specifically, the engine braking valve 104b) will experience a lift exceeding the main event valve actuation, causing the engine valve 104 to extend further into the cylinder bore and potentially leading to catastrophic contact between the piston and the engine valve 104. One solution to this problem is to allocate more space in the piston bore or less piston stroke to avoid contact with the engine valve 104. However, this solution is undesirable because the engine braking power will be reduced due to the reduced volume in both the compression and exhaust strokes.

[0006] Regarding the latter, the seat speed is another issue because the braking components of the rocker arm cause a higher seat speed for the non-braking valve 104a. A high seat speed can lead to accelerated seat wear and potential failure of the engine valves or their corresponding seats.

[0007] As is known in the art, one way to solve these problems is to integrate the reset component 118 into the IRB system, such as Figure 1 As further illustrated below. Typically, the reset assembly 118 is provided by one or more components external to the IRB 100, such as... Figure 1 As illustrated in the illustration. Alternatively, the reset assembly 118' may be incorporated into the IRB 100 itself. In any case, such reset assemblies 118, 118' are typically operated by providing hydraulic connections 120, 120' that can be controlled (typically by means of angular positioning of the rocker arm 100 relative to another valve train component or fixed surface) to selectively and rapidly ventilate the high-pressure chamber 116, thereby causing the actuator piston to retract or collapse, and transmitting control of the engine braking valve 104 to the main event valve actuation movement, and thus preventing its overextension and preventing high seat speeds of non-braking valves.

[0008] Technologies that enable the benefits of IRB systems to be realized in a wider range of internal combustion engines would represent a welcome addition to the field. Summary of the Invention

[0009] The aforementioned drawbacks of prior art solutions are addressed by providing an IRB-type rocker arm configured to actuate at least one engine valve in an internal combustion engine. In one embodiment, the rocker arm, including a motion-applying end, further includes a biasing contact surface configured to receive a force to bias the motion-applying end toward at least one first engine valve. An actuator piston is slidably disposed in a vertical bore formed in the motion-applying end of the rocker arm, wherein the actuator piston and the vertical bore are configured to align with at least one first engine valve. The rocker arm also includes: a hydraulic chamber in fluid communication with the vertical bore; and a checking element in fluid communication with the hydraulic chamber and configured to allow selectively applied hydraulic fluid to enter the hydraulic chamber unidirectionally. A reset plunger is disposed in the rocker arm and sealably engages with a reset plunger orifice, which in turn is in fluid communication with the hydraulic chamber. The reset plunger has an end that extends out of the rocker arm and is configured to contact a reaction surface outside the rocker arm in response to the positioning of the rocker arm, thereby interrupting the sealing engagement of the reset plunger with the reset plunger bore and allowing hydraulic fluid to drain from the hydraulic chamber.

[0010] In one embodiment, a biasing contact surface is disposed on the upward-facing surface of the rocker arm. In another embodiment, the rocker arm includes a lateral protrusion, and the biasing contact surface is formed on the lateral protrusion.

[0011] In one embodiment, the actuator piston includes a resilient element for biasing the actuator piston into a vertical bore. In one example, the resilient element includes an actuator piston spring disposed within the actuator piston and the vertical bore and configured to bias the actuator piston into the vertical bore.

[0012] In one embodiment, the hydraulic chamber includes a first hole parallel to the axis of rotation of the rocker arm, wherein the inspection element is arranged in the first hole.

[0013] In one embodiment, the reset plunger is biased to seal against a reset plunger bore. For example, the rocker arm may also include a reset plunger spring configured to bias the reset plunger to seal against the reset plunger bore. In one embodiment, the reset plunger bore is perpendicular to the axis of rotation of the rocker arm. The rocker arm may include a reset plunger sleeve disposed within a second bore formed in the rocker arm, wherein the reset plunger sleeve defines the reset plunger bore.

[0014] In one embodiment, a valve actuation system for actuating at least a first engine valve includes a rocker arm of the present disclosure, wherein the rocker arm is rotatably mounted on a rocker arm shaft, and wherein an elastic element is attached to the rocker arm shaft and configured to apply a force to a bias contact surface.

[0015] In one embodiment, a valve actuation system for actuating at least a first engine valve includes the rocker arm of this disclosure, and further includes a fixed structure for movement relative to the rocker arm, wherein a reaction surface is formed on the fixed structure. In one specific embodiment, the fixed structure is a camshaft bearing support.

[0016] In one embodiment, a valve actuation system is configured to actuate at least two engine valves and includes a rocker arm of the present disclosure, wherein the at least two engine valves include at least a first engine valve. In one embodiment, the system includes a further rocker arm for actuating a second engine valve of the at least two engine valves. In another embodiment, the system further includes a first valve actuation motion source configured to provide a primary event valve actuation motion and one or more first auxiliary valve actuation motions to at least the first engine valve. In yet another embodiment, the system includes a second valve actuation motion source configured to provide a primary event valve actuation motion and one or more second auxiliary valve actuation motions to a second engine valve, wherein the first auxiliary valve actuation motions differ from the second auxiliary valve actuation motions. In yet another embodiment of the system, another rocker arm is a rocker arm according to the present disclosure, wherein the actuator piston and vertical bore of the other rocker arm are configured to align with the second engine valve. Attached Figure Description

[0017] The foregoing and other features and advantages will be discussed in detail in the following non-limiting description of a particular embodiment, in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of an IRB system based on existing technology; Figure 2 This is a schematic diagram of a single-valve IRB system according to this disclosure; Figure 3 This is an isometric view of the IRB system according to this disclosure; Figure 4 This is an isometric view of an IRB rocker arm for use with a single engine valve, according to this disclosure; Figure 5 and Figure 6 yes Figure 4 A partial front sectional view of the IRB rocker arm, illustrating further details of the actuator and reset assembly according to this disclosure; and Figure 6 yes Figure 4 A top partial sectional view of a portion of the IRB rocker arm, and further details of the actuator and reset assembly according to this disclosure are illustrated. Detailed Implementation

[0018] As used herein, phrases substantially similar to "at least one of A, B, or C" are intended to be interpreted as disjunctive terms, requiring A or B or C, or any combination thereof, unless the context otherwise indicates or implies. Furthermore, phrases substantially similar to "at least one of A, B, and C" are intended to be interpreted as conjunctions, requiring at least one of A, at least one of B, and at least one of C, unless the context otherwise indicates or implies. In addition, the term "substantially" or similar terms requiring subjective comparison are intended to mean "within manufacturing tolerances," unless the context otherwise indicates or implies.

[0019] As used herein, the phrase “operationally connected” refers to at least a functional relationship between two elements and may cover configurations in which the two elements are directly connected to each other (i.e., without any intermediate elements) or indirectly connected to each other (i.e., with intermediate elements).

[0020] As used herein, the phrase “fluid connectivity” refers to a configuration between two or more elements in which fluid can flow between such elements in at least one direction.

[0021] This disclosure describes an embodiment of an IRB-type rocker arm for actuating a single engine valve, rather than an intermediate valve bridge configured to actuate two or more engine valves. However, it should be understood that the IRB-type rocker arm described herein can also be used to actuate two or more engine valves via an intermediate valve bridge. Additionally, the disclosed IRB-type rocker arm described herein includes a reset assembly. Reference Figure 2 An example of a valve actuation system 200 according to this disclosure is further described.

[0022] Figure 2 An example of a valve actuation system 200 is illustrated, which is configured to actuate two engine valves 206 and 212 associated with an internal combustion engine cylinder 201. Specifically, the illustrated valve actuation system 200 includes: a first rocker arm 202 operatively connected to a first valve actuation motion source 204 and a first engine valve 206; and a second (or IRB) rocker arm 208 operatively connected to a second valve actuation motion source 210 and a second engine valve 212. That is, with Figure 1 Unlike conventional IRB systems of the type illustrated herein, each engine valve 206, 212 is actuated according to separate valve actuation motion sources 204, 210 and rocker arms 202, 208, thereby eliminating the need for a valve bridge. As those skilled in the art will understand, Figure 2Other valve train components not illustrated herein (e.g., pushrods, tappets, etc.) may be incorporated into corresponding valve mechanisms including the first rocker arm 202 and the second rocker arm 208. The first engine valve 206 and the second engine valve 212 are preferably of the same type, i.e., both are intake valves or both are exhaust valves. Furthermore, both the first valve actuation source 204 and the second valve actuation source 210 may be implemented as suitable cams known in the art.

[0023] Specifically, in one embodiment, the first valve actuation motion source 204 may include a convex angle for providing primary event valve actuation motion, while the second motion source 210 may include both a convex angle for primary event valve actuation motion and one or more engine braking valve actuations specifically implemented using so-called base circles and sub-base circles known in the art. Alternatively, in addition to the convex angle providing primary event valve actuation motion, the first valve actuation motion source 204 may also include an additional convex angle for providing additional auxiliary valve actuation motion. That is, more generally, in the various valve actuation systems described herein, the first motion source 204 may be configured to provide only primary event valve actuation motion, or primary event valve actuation motion together with one or more first auxiliary valve actuations, while the second motion source may be configured to provide primary event valve actuation motion together with one or more second auxiliary valve actuations. In this case, the first auxiliary valve actuation motion and the second auxiliary valve actuation motion need not be identical to each other. For example, when provided, the first auxiliary valve actuation movement can be configured to provide early exhaust valve opening (EEVO), while the second auxiliary valve actuation movement can be configured to provide compression-release engine braking.

[0024] As depicted, the first rocker arm 202 actuates the first engine valve 206 in a conventional manner, i.e., according to the valve actuation motion received by the first rocker arm 202 from the first motion source 204 and transmitted to the first engine valve 206. Similarly, the second rocker arm 208 receives valve actuation motions from the second motion source 210 and transmits them to the second engine valve 212. However, unlike the first rocker arm 202, the second rocker arm 208 implements various components consistent with IRB operation.

[0025] Specifically, the second rocker arm 208 includes a selectable actuator 214 configured to transmit engine brake valve actuation motion (received from the second motion source 210) to the second engine valve (also referred to as the engine brake valve) 212. Figure 2As further shown, control of actuator 214 is provided by an optional hydraulic fluid supply 216, which is operated to provide hydraulic fluid via a check element 218 (which, as is known in the art, may include a check valve, which may then be incorporated into a control valve). For example, the flow of hydraulic fluid from fluid supply 216 can be controlled using a solenoid commanded by a suitable processing device, such as an engine control unit (ECU) (not shown) known in the art. In the absence of a hydraulic fluid supply to check element 218, the actuator piston of actuator 214 remains in a retracted or compliant state, such that no auxiliary valve actuation (i.e., valve actuation received by the second rocker arm 208 only when the second rocker arm 208 is controlled to contact the subbase circle of the second motion source 210) is transmitted by actuator 214 to the second engine valve 212.

[0026] On the other hand, when hydraulic fluid is supplied to the inspection element 218, the hydraulic fluid is then supplied to the hydraulic or high-pressure chamber 220, which is in fluid communication with the actuator piston of the actuator 214. The inspection element 218 is used to inspect the hydraulic fluid in the high-pressure chamber 220, thereby maintaining hydraulic lock on the fluid in the high-pressure chamber 220. As long as the hydraulic lock is maintained, the actuator piston remains in the extended state, thereby delivering the subbase circle auxiliary valve actuation motion to the second engine valve 212.

[0027] like Figure 2 As further shown, the second rocker arm 208 is coupled to a reset assembly 222. As shown, the reset assembly 222 is configured to have a hydraulic connection 224 with the high-pressure chamber 220. The reset assembly 222 can be controlled by interaction with a fixed reaction surface 226 (fixed relative to the typical reciprocating motion of the rocker arm 208) to selectively and rapidly ventilate the high-pressure chamber 220, thereby causing the actuator piston of actuator 214 to retract or collapse. This, in turn, causes the second rocker arm 208 to lose contact with the sub-base circle of the second motion source 210, thus losing the auxiliary valve actuation provided by the second motion source 210.

[0028] Figure 2 A biasing contact surface 215 is also schematically illustrated, formed on the second rocker arm 208 and configured to receive a force 217 that biases the second rocker arm 208 toward the second engine valve 212. This biasing is desired in order to control the inertia of the rocker arm 208. As those skilled in the art will understand, the biasing contact surface 215 may be formed at different locations on the second rocker arm 208 depending on the location of the fulcrum of the second rocker arm.

[0029] Additionally, it should be noted that, although Figure 2An example is a valve actuation system 200, in which two rocker arms 202, 208 are provided to individually actuate two engine valves 206, 212 (intake or exhaust) of the same type, but this is not necessary. That is, in some internal combustion engines, only one engine valve of a given type may be provided for cylinder 201, for example, a single exhaust valve. In this case, the IRB rocker arm 208 as described herein can be used to actuate the single valve with and without auxiliary event valve actuation movements (in addition to the main event valve actuation movements). Alternatively, in systems in which two or more engine valves of the same type are provided for cylinder 201, the IRB rocker arm 208 can still be used to actuate two or more engine valves via, for example, an intermediate valve bridge.

[0030] In yet another embodiment, the conventional first rocker arm 202 may be replaced by an IRB rocker arm that is substantially the same in structure and operation as the second rocker arm 208. In this way, particularly when the first motion source is configured to provide main valve actuation motion and one or more first auxiliary valve actuation motions and the second motion source is configured to provide main valve actuation motion and one or more second auxiliary valve actuation motions, as mentioned above, the use of the two IRB rocker arms according to this disclosure allows the combination of main valve actuation motion, first auxiliary valve actuation motion, and second auxiliary valve actuation motion to be selectively applied to the first engine valve 206 and the second engine valve 212.

[0031] Figure 2 The specific implementation of the valve actuation system is as follows: Figures 3 to 7 Example. Specifically, Figure 3 An example of a valve actuation system 300 is illustrated, comprising a first rocker arm 302 and a second rocker arm 308, both rotatably mounted on a rocker arm shaft 330. The first rocker arm 302 is configured to actuate a first engine valve 306, and the second rocker arm 308 is configured to actuate a second engine valve 312, these engine valves being biased to their closed or seated positions by corresponding valve springs 338, 340. A camshaft 332 is supported by an upper camshaft bearing support 334 and a lower camshaft bearing support 336, the camshaft 332 providing a first cam 304 and a second cam 310 aligned with the first rocker arm 302 and the second rocker arm 308, respectively. Figure 2 In one embodiment, the first cam 304 includes a cam angle that provides primary event valve actuation, while the second cam 310 includes a cam angle that provides substantially the same primary event valve actuation movement as the first cam 304 and one or more cam angles that provide one or more auxiliary valve event actuation movements (such as engine braking).

[0032] like Figure 3As further shown in the embodiment, a fixed (relative to the rotational / reciprocating movement of the second rocker arm 308) reaction surface 342 is provided by an upper camshaft bearing support 336, which aligns with a reset plunger 344 provided by the second rocker arm 308. As described in further detail below, the reaction surface 342 and the reset plunger 344 are configured such that contact between them occurs at the desired rotational positioning of the second rocker arm 308, thereby achieving the reset as described above. As those skilled in the art will understand, depending on the engine configuration, the reaction surface 342 may be provided by some other fixing structure.

[0033] In one embodiment, the second rocker arm 308 includes a biasing contact surface formed on the upper surface of the second rocker arm 308, and more particularly, is configured such that applying a force to the biasing contact surface will tend to bias the second rocker arm 308 toward the second engine valve 312. Figure 3 A specific example of this situation is illustrated in the figure, which shows a lateral protrusion 348 extending from the second rocker arm 308 in a direction substantially parallel to the axis of rotation of the second rocker arm 308 (i.e., the longitudinal axis of the rocker arm shaft 330). Figure 3 Additionally, an elastic element in the form of a flat spring 346 is illustrated, which is attached adjacent to the second rocker arm 308 and aligned with the lateral protrusion 348 of the second rocker arm 308 to the rocker arm shaft 330 (i.e., the fixing structure outside the second rocker arm 308). The spring 346 is configured such that the second rocker arm 308 is biased toward its corresponding second engine valve 312, particularly when the second rocker arm 308 contacts the second cam 310 only at its base circle (opposite to its sub-base circle). Those skilled in the art will understand that other configurations of the elastic element for biasing the second rocker arm 308 in this manner can be readily designed.

[0034] Although the biasing contact surface described herein is preferably configured to bias the rocker arm toward the engine valve, the biasing contact surface may also be configured toward the valve actuation motion source.

[0035] See now Figure 4 A more detailed view of the second rocker arm 308 is shown. Specifically, the second rocker arm includes a rocker arm body 402 having a motion receiving end 404 and a motion imparting end 406. According to known art, the motion receiving end 404 is equipped with a roller follower 408 configured to receive valve actuation motion from a valve actuation motion source (e.g., the second cam 310). The motion imparting end 406 includes an actuator boss 410, a check valve boss 412, and a reset assembly boss 414, the respective configuration of each boss and their relationship to each other described in further detail below.

[0036] The rocker arm body 402 also includes a rocker arm shaft opening 416, which is formed between the motion receiving end 404 and the motion imparting end 406 and is received to receive the rocker arm shaft 330. Figure 4 (Not shown in the image). According to known technology, the inner surface of the rocker arm shaft opening 416 may have one or more hydraulic passages 418 formed therein. As is known in the art, the hydraulic passages 418 are configured to receive hydraulic fluid from corresponding hydraulic passages formed in the rocker arm shaft 330, which can be used to control the operation of the second rocker arm 308, as further described below.

[0037] The rocker arm body 402 also includes a lateral protrusion 348 at its motion-giving end 406, which extends substantially perpendicularly (or substantially parallel to the axis of rotation of the second rocker arm 308) relative to the plane in which the second rocker arm 308 rotates. As shown, the lateral protrusion 348 may include a substantially flat surface configured to... Figure 3 The flat spring 346 shown establishes contact. In this configuration, the contact between the lateral protrusion 348 and the spring 346 imparts movement to the end 406 as... Figure 4 The depicted counterclockwise rotation (i.e., towards the corresponding engine valve).

[0038] like Figure 4 As further shown, the reset assembly boss 414 includes a downwardly extending reset plunger 344 (e.g. Figure 4 (as depicted), and the actuator boss 410 includes a threaded clearance adjusting screw 424 that extends therein and is secured by a clearance adjusting nut 426. A swivel ring, or so-called elephant foot 428, is attached to the actuator piston (not shown) and is configured to contact the second engine valve 312.

[0039] The following text combines Figures 5 to 7 Further details of the second rocker arm 308 are described, and these figures show various sectional views.

[0040] Figure 5 Examples are shown along Figure 4 The section shown is a partial frontal sectional view of the second rocker arm 308, taken by section line VV. Figure 5Specifically illustrated are the reset assembly boss 414, the reset assembly 502, and the check valve boss 412 housed therein. The check valve boss 412 includes a horizontal bore 504, and the reset assembly boss 414 includes a vertical bore 506 in fluid communication with each other at a first intersection. The horizontal bore 504 terminates at one end (the second intersection) in fluid communication with a hydraulic fluid inlet 508 and is sealed at the other end by a threaded plug 510, thereby forming a hydraulic chamber 512. The check valve 514 is disposed within the horizontal bore 504 located between the first and second intersections. In the illustrated embodiment, the check valve 514 includes a check valve body 516 and a check ball 518 biased by a check valve spring 520 into contact with a seat defined by the check valve body 516. In this way, a unidirectional fluid flow is established from the hydraulic fluid inlet 508 into the hydraulic chamber 512.

[0041] The reset assembly 502 also includes a sleeve 522 disposed in a vertical bore 506, defining a sleeve bore 524. The sleeve 522 may be press-fitted into the vertical bore 506 or using other known techniques (e.g., threaded engagement). A reset plunger 344 is slidably disposed in the sleeve bore 524 and includes a plunger contact surface 526 that terminates an end of the reset plunger extending out of the sleeve bore 524. In the currently preferred embodiment, the plunger contact surface 526 has a curvature that allows the reset plunger 344 to maintain smooth and uniform contact with the reaction surface 342 throughout rotation of the second rocker arm 308 relative to the reaction surface 342. The reset plunger 344 also includes a head 528 configured to correspond to a seat 530 formed in the upper end of the sleeve 522. A reset plunger spring 532 is disposed in a hydraulic chamber 512 that contacts the reset plunger 344 and is configured to bias the reset plunger 344 out of the sleeve bore 524. However, the reset plunger 344 is prevented from slipping out of the sleeve 522 by conformal contact or sealing engagement between the plunger head 528 and the seat ring 530, thereby providing a seal to prevent the escape of hydraulic fluid disposed in the hydraulic chamber 512.

[0042] In the illustrated embodiment, the generally cylindrical reset plunger 344 also includes a flat surface 534, such as Figure 5 and Figure 6As shown. When the reset plunger 344 is pushed upward by contacting the reaction surface 342 and resisting the bias of the reset plunger spring 532, the seal provided by the conformal contact of the plunger head 528 and the seat ring 530 is interrupted, thereby providing a fluid communication path between the hydraulic chamber 512 and the channel 536, which is established between the wall defining the sleeve bore 524 and the flat surface 534. When established, this fluid communication allows hydraulic fluid in the hydraulic chamber 512 to escape into the environment via the channel 536. As described in further detail below, selective control of the hydraulic fluid in the first hydraulic chamber by means of the operation of the reset plunger 344 allows the actuator piston to extend and retract as needed to achieve the reset of the IRB rocker arm 308.

[0043] Figure 6 Examples are shown along Figure 4 The diagram shows a front sectional view of the second rocker arm 308, taken along section line VI-VI. Specifically, Figure 6 An actuator boss 410 and an actuator assembly 602 housed therein are illustrated. The actuator boss 410 includes a vertical bore 604 formed therein and has a downwardly opening end and a closed end. An actuator piston 606 is slidably disposed in the vertical bore 604 and includes a ball 608 formed on an end of the actuator piston 606. A swivel ring 428 is rotatably connected to the ball 608 using known techniques. Further according to known techniques, a gap adjusting screw 424 is threaded onto the actuator boss 410 such that the gap adjusting screw extends through the vertical bore 604 and the closed end of the actuator piston bore 610 formed in the actuator piston 606 and enters the vertical bore and the actuator piston bore. In one embodiment, a flange 612 is slidably mounted on the gap adjusting screw 424 and attached to the actuator piston 606 at the open end of the actuator piston bore 610. Furthermore, in this embodiment, the actuator spring 614 is disposed between and acts between the shoulder 616 and the flange 612, the shoulder being formed on the distal end of the clearance adjusting screw 424 (relative to the clearance adjusting nut 426). In this way, the actuator piston 606 is biased into the vertical bore 604, such that a firm contact is established between the clearance adjusting screw 424 and the actuator piston 606 even without hydraulic actuation of the actuator piston 606, as... Figure 6 As shown. Although Figure 6 The embodiment illustrates an actuator spring 614 disposed within the actuator piston 606 and the vertical bore 604, but it should be understood that this is not necessary; that is, the actuator spring 614 may be disposed outside the actuator piston 606, and even outside the vertical bore 604.

[0044] In another embodiment, the actuator spring 614 is not provided. In this case, without hydraulic actuation of the actuator piston 606, the actuator piston 606 is maintained in its retracted position by the bias applied to the second rocker arm 308 by the flat spring 346.

[0045] Figure 6 An intermediate hydraulic passage 618, formed in the second rocker arm 308 and in fluid communication with the vertical bore 604, is also illustrated. The intersection of the intermediate hydraulic passage 618 and the vertical bore 604 is configured such that fully pressurized hydraulic fluid supplied through the intermediate hydraulic passage 618 flows into the vertical bore 604, passes through the flange 612, and contacts the actuator piston 606. In one embodiment, the hydraulic pressure thus applied to the actuator piston 606 is sufficient to overcome the bias of the actuator piston spring 614 (if provided), causing the actuator piston 606 to extend out of the vertical bore 604, i.e., so that there is no longer a firm contact between the clearance adjusting screw 424 and the actuator piston 606. Figure 7 (This illustration shows along such) Figure 4 (A partial cross-sectional view of the second rocker arm 308 taken by section line VII-VII) further shows that the intermediate hydraulic passage 618 establishes fluid communication between the hydraulic chamber 512 and the vertical hole 604.

[0046] Configure it in this way, and refer to Figure 3 and Figures 5 to 7 When hydraulic fluid is not supplied to the hydraulic chamber 512 via the hydraulic fluid inlet 508, hydraulic fluid is also not supplied to the vertical bore 604, and the actuator piston 606 remains in its stationary or non-actuated position, i.e., biased into the vertical bore 604 and in firm contact with the clearance adjusting screw 424 (or at least in a compliant state without the actuator spring 614). Because the second rocker arm 308 is biased toward the second engine valve 312 by the flat spring 346, the second rocker arm 308 is positioned at the level of the base circle of the second cam 310, such that any cam lift below the base circle (e.g., auxiliary valve actuation movements, such as engine braking) is lost, while cam lift above the base circle (e.g., primary event valve actuation movements) is received by the second rocker arm 308 and transmitted to the second engine valve 312 by means of the firm contact between the clearance adjusting screw 424 and the actuator piston 606.

[0047] However, when hydraulic fluid is supplied to the hydraulic chamber 512 via the hydraulic fluid inlet 508, the hydraulic fluid flows through the hydraulic chamber 512 and the intermediate hydraulic passage 618 and into the vertical bore 604, causing the actuator piston 606 to extend out of the vertical bore 604, i.e., into its actuated position. Once the hydraulic chamber 512, the intermediate hydraulic passage 618, and the vertical bore 604 are filled with hydraulic fluid, the pressure on either side of the check valve 514 is balanced and allows the check ball 518 to reset, thereby establishing a locked volume of hydraulic fluid behind the actuator piston 606, which then remains in its extended state. Because the second rocker arm 308 continues to be biased to contact the second engine valve 312, the extension of the actuator piston 306 against the resistance of the engine valve 312 (caused by the valve spring 340) will overcome the bias of the flat spring 346 (and the actuator spring 614, if provided). Subsequently, the second rocker arm 308 will rotate toward the second cam 310, such that the second rocker arm 308 is positioned at the level of the sub-base circle of the second cam 310. Thus, any cam lift below the level of the base circle will be received by the second rocker arm and transmitted to the second engine valve 312 via the now extended actuator piston 606.

[0048] However, as described above, if the actuator piston 606 remains extended during the lift provided by the main event valve actuation motion, overextension of the second engine valve 312 will occur, potentially leading to contact with the cylinder piston and catastrophic damage. To prevent such overextension, the reset plunger 344 and the reaction surface 342 are configured such that contact is established between them when the rotation of the second rocker arm 308 corresponds to a lift sufficient to ensure no loss of the main event due to overextension. This could occur, for example, at a lift height corresponding to a large portion of the maximum main event lift, or at any other desired lift, such as at or just below the base circle level of the second cam 310. As described above, this contact between the reset plunger 344 and the reaction surface 342 causes the plunger head 528 to lift from the seat ring 530, thereby allowing hydraulic fluid that was originally trapped in the hydraulic chamber 512, the intermediate hydraulic passage 618, and the vertical bore 604 to escape (especially rapidly when such hydraulic fluid is highly pressurized, such as during cam lift / valve actuation). This discharge of hydraulic fluid allows the actuator piston 606 to be positioned again solely by the bias of the actuator piston spring 614, i.e., back into the vertical bore 604, which in turn allows the second rocker arm 308 to be positioned again solely by the flat spring 346, i.e., toward the second engine valve 312 and positioned at the base circle level relative to the second cam 310.

[0049] While various embodiments of the invention have been described in conjunction with specific embodiments thereof, it will be apparent to those skilled in the art that many substitutions, modifications, and variations will be readily apparent. Therefore, the preferred embodiments of the invention described herein are merely illustrative and not restrictive, provided that variations fall within the scope of the appended claims and their equivalents.

Claims

1. A rocker arm for actuating at least a first engine valve in an internal combustion engine and having a motion-granting end, the rocker arm comprising: A biased contact surface, the biased contact surface being configured to receive forces to impart the motion to the end of the at least first engine valve bias; An actuator piston is slidably disposed in a vertical bore formed in the motion-giving end of the rocker arm, the actuator piston and the vertical bore being configured to align with the at least first engine valve; The hydraulic chamber is in fluid communication with the vertical hole; An inspection element is in fluid communication with the hydraulic chamber and is configured to allow selectively applied hydraulic fluid to enter the hydraulic chamber in one direction only. and A reset plunger is sealed to a reset plunger bore that is in fluid communication with the hydraulic chamber. The reset plunger has an end that extends out of the rocker arm and is configured to contact a reaction surface outside the rocker arm in response to positioning of the rocker arm, thereby interrupting the sealed engagement of the reset plunger with the reset plunger bore and allowing hydraulic fluid to drain from the hydraulic chamber.

2. The rocker arm according to claim 1, wherein the bias contact surface is disposed on the upward surface of the rocker arm.

3. The rocker arm according to claim 2, the rocker arm including a lateral protrusion, wherein the biasing contact surface is formed on the lateral protrusion.

4. The rocker arm of claim 1, wherein the actuator piston includes an elastic element for biasing the actuator piston into the vertical bore.

5. The rocker arm according to claim 4, further comprising: An actuator piston spring is disposed within the actuator piston and the vertical bore and is configured to bias the actuator piston into the vertical bore.

6. The rocker arm of claim 1, wherein the hydraulic chamber includes a first hole parallel to the axis of rotation of the rocker arm, wherein the inspection element is disposed in the first hole.

7. The valve actuation system of claim 1, wherein the reset plunger is biased to seal against the reset plunger orifice.

8. The rocker arm of claim 7, further comprising a reset plunger spring configured to bias the reset plunger into a sealing engagement with the reset plunger bore.

9. The rocker arm according to claim 1, wherein the reset plunger hole is perpendicular to the rotation axis of the rocker arm.

10. The rocker arm according to claim 9, further comprising a reset plunger sleeve disposed within a second hole formed in the rocker arm, the reset plunger sleeve defining the reset plunger hole.

11. A valve actuation system for actuating a first engine valve and including a rocker arm according to claim 1, wherein the rocker arm is rotatably mounted on a rocker arm shaft, the system further including an elastic element attached to the rocker arm shaft and configured to apply the force to the bias contact surface.

12. A valve actuation system for actuating a first engine valve and including a rocker arm according to claim 1, the system further including a fixed structure movable relative to the rocker arm, wherein the reaction surface is formed on the fixed structure.

13. The valve actuation system according to claim 12, wherein the fixing structure is a camshaft bearing support.

14. A valve actuation system for actuating at least two engine valves, wherein the at least two engine valves include a first engine valve, and the valve actuation system includes a rocker arm according to claim 1.

15. The valve actuation system of claim 14, further comprising another rocker arm for actuating a second engine valve of the at least two engine valves.

16. The valve actuation system of claim 15, further comprising a first valve actuation motion source configured to provide a primary event valve actuation motion and one or more first auxiliary valve actuation motions to the first engine valve.

17. The valve actuation system of claim 16, further comprising a second valve actuation motion source configured to provide the primary event valve actuation motion and one or more second auxiliary valve actuation motions to the second engine valve, wherein the first auxiliary valve actuation motion is different from the second auxiliary valve actuation motion.

18. A valve actuation system for actuating at least two engine valves, wherein the at least two engine valves include a first engine valve, wherein the system includes a first rocker arm for actuating the first engine valve and a second rocker arm for actuating a second engine valve of the at least two engine valves, and wherein the first rocker arm and the second rocker arm are rocker arms according to claim 1.

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