Independent compression brake control module and method for integrated rocker arm engine braking

Abstract

An exhaust rocker arm assembly for operating an engine exhaust valve during a compression release engine brake operation. The exhaust rocker arm assembly includes an exhaust rocker arm, and a stand-alone compression brake control module (CBCM) mounted on the exhaust rocker arm and operatively coupled with the exhaust valve for controlling the lift and phase angle thereof. The CBCM includes a housing, an actuating piston disposed outside the housing to define an actuating piston cavity, a reset check valve disposed between the housing and the actuating piston, and a compression brake actuator disposed within the housing. The actuating piston reciprocates relative to the housing. The compression brake actuator includes a control piston. The control piston, when deactivated, engages the check valve to unlock the actuating piston cavity, and when activated, disengages the check valve to lock the actuating piston cavity.

Description

Technical Field

[0001] The present invention generally relates to a compression-release brake system for an internal combustion engine, and more specifically, to a self-contained compression-release brake control module for an internal combustion engine compression-release brake system, and a method of using such a self-contained compression-release brake control module for an internal combustion engine compression-release brake system. Background Technology

[0002] For internal combustion engines, especially diesel engines in large trucks, engine braking is a crucial feature for enhancing vehicle safety. Therefore, diesel engines in vehicles (particularly large trucks) are typically equipped with compression-release engine braking systems (or compression-release retarders) to slow the engine (and thus the vehicle) to decelerate the truck. Compression-release engine braking provides significant braking power in operational braking modes. For this reason, compression-release engine braking systems have been widely adopted in North America since the 1960s.

[0003] A typical compression-release engine braking system opens one or more exhaust valves just before Top Dead Center (TDC) at the end of the compression stroke. This causes disturbance to the compressed cylinder gases, and the energy accumulated during compression cannot be recovered. The result is engine braking or deceleration. Traditional compression-release engine braking systems have significant costs associated with the hardware required to open the exhaust valves (one or more) against the extremely high loads applied to the compression cylinder. Valve train components must be designed and manufactured to operate reliably under high mechanical loads and engine speeds. Furthermore, the sudden release of highly compressed gases is accompanied by high noise levels. In some areas, often urban areas, engine braking is prohibited because existing compression-release engine braking systems rapidly open the valves at high compression pressures near TDC, generating high engine valve train loads and loud noise. It is this loud noise that leads to the banning of compression-release brakes in some urban areas.

[0004] Typically, compression-release engine braking systems to date are unique, meaning they are custom-designed and manufactured for specific engine brands and models. Design, prototyping, bench testing, engine testing, and field testing usually take twenty-four (24) months to complete before they can be released for sale. Therefore, development time and cost have always been areas of concern.

[0005] Exhaust braking systems can be used on engines where the compression-release load is too high for the valve train. An exhaust braking system includes a restrictor element installed in the exhaust system. When this restrictor is closed, back pressure resists the expulsion of gases in the exhaust cycle, providing braking. This system provides less braking power than compression-release engine braking, but is also less expensive. Like compression-release braking, the retarding power of exhaust braking decreases sharply as engine speed decreases. This is because the restrictor is optimized to generate the maximum permissible back pressure at rated engine speed. At lower engine speeds, the restrictor is simply insufficient to function.

[0006] US8,272,363 describes a stand-alone compression brake control module (CBCM) for controlling exhaust valve movement, primarily for, but not limited to, engine deceleration. The CBCM described in US8,272,363 typically requires a significant axial offset between the longitudinal axis of the CBCM and the longitudinal valve axis of the exhaust valve it acts upon, as in US8,272,363. Figure 2A -As shown in Figure 2C. The CBCM described in US8,272,363 includes an actuation piston retaining ring and a seal that engages with the same orifice within a single housing of the CBCM. Because the seal's passage through the retaining ring groove needs to be considered during assembly, this results in a higher diameter requirement for some of the orifices. The CBCM in US8,272,363 utilizes a housing containing the actuation piston, while also requiring a support housing, which increases the overall assembly diameter. These factors, leading to the required offset, create lateral forces acting on the actuation piston of the CBCM, potentially causing wear and / or jamming of the actuation piston within its orifice. Practical applications of CBCMs often require a reduction in overall height and diameter to fit into existing engine kits without interfering with or wanting to alter other components. Therefore, it is advantageous to be able to reduce the size of the CBCM module, allowing for better focus on the load generated by the exhaust valves and enabling it to be packaged within smaller space constraints.

[0007] Similarly, US 11,149,659 (which is incorporated herein by reference) describes a stand-alone, compact hydraulic compression brake control module for selectively modifying the lift and phase angle of the exhaust valve. The brake control module in US 11,149,659 is disclosed to be fixed in position relative to the cylinder head of a diesel engine.

[0008] Modern engine compression-release engine braking systems typically integrate critical engine braking components into rocker arms. Therefore, the rocker arms are movably positioned relative to the cylinder head of the diesel engine. Examples include lostmotion compression-release engine brake systems and dedicated cam compression-release engine brake systems. Lostmotion compression-release engine brake systems position components within the exhaust rocker arm, while dedicated cam compression-release engine brake systems position components within a dedicated engine braking rocker arm (independent of the intake and exhaust rocker arms).

[0009] While known compression-release engine braking systems have proven effective in various vehicle engines, these systems require further improvement to enhance their performance and cost. Therefore, there is a need to develop improved compression-release engine braking systems to advance this field, such as a stand-alone compression brake control module for internal combustion engine compression-release braking systems capable of performing both "dedicated cam" engine braking and "disengagement" and "dedicated cam" engine braking. Such a system should be easier to assemble, more robust and compact after assembly, while simultaneously improving performance, enhancing functionality, and significantly reducing the development time and cost of compression-release engine braking systems. Summary of the Invention

[0010] According to a first aspect of the invention, an exhaust trocker assembly is provided for operating at least one exhaust valve of an internal combustion engine during compression-release engine braking operation. The exhaust trocker assembly includes an exhaust trocker arm and a separate compression braking control module mounted on the exhaust trocker arm and operatively coupled to the at least one exhaust valve for controlling the lift and phase angle of the at least one exhaust valve. When the internal combustion engine performs compression-release engine braking operation, the compression braking control module keeps the at least one exhaust valve open during the compression stroke of the internal combustion engine. The compression braking control module includes a hollow housing comprising a single piece mounted in the exhaust trocker arm, and a hollow actuating piston disposed outside the housing and in the exhaust trocker arm to define a variable-volume hydraulic actuating piston chamber between the hollow housing and the actuating piston. The housing defines an internal actuator chamber therein and includes a hollow interior spaced away from the internal actuator chamber. The actuating piston reciprocates between an extended position and a retracted position relative to the hollow interior of the hollow housing, and when the actuating piston is in the extended position, the actuating piston is configured to engage the at least one exhaust valve. The aforementioned actuating piston chamber and internal actuator chamber are fluidly connected to each other via a connecting channel in the aforementioned hollow housing. The hollow interior of the hollow housing extends into the actuating piston. The aforementioned compression brake control module also includes a reset check valve between the aforementioned connecting channel and the actuating piston chamber, and a compression brake actuator located in the aforementioned internal actuator chamber and configured to control the reset check valve. When the hydraulic fluid pressure in the actuating piston chamber exceeds the hydraulic fluid pressure in the supply port within the hollow housing, the aforementioned reset check valve is configured to hydraulically lock the actuating piston chamber. The aforementioned reset check valve is biased closed by a bias spring. The aforementioned compression brake actuator includes a control piston exposed to atmospheric pressure. The control piston is slidably mounted in the aforementioned internal actuator chamber to reciprocate between an extended position and a retracted position. The aforementioned compression braking control module also includes a control piston spring configured to bias the control piston toward its retracted position, wherein the control piston engages and opens the reset check valve solely by the biasing force of the control piston spring to unlock the actuation piston chamber and fluidly connect the actuation piston chamber to the aforementioned supply port.

[0011] According to a second aspect of the invention, a method is provided for operating an exhaust rocker arm assembly of at least one exhaust valve of an internal combustion engine during a compression-release engine braking operation. The exhaust rocker arm assembly includes an exhaust rocker arm having a control hole formed therein, and a separate compression braking control module mounted on the exhaust rocker arm and operatively connected to at least one exhaust valve for controlling the lift and phase angle of the at least one exhaust valve. When the internal combustion engine performs a compression-release engine braking operation, the compression braking control module keeps the at least one exhaust valve open during the compression stroke of the internal combustion engine. The compression braking control module includes a hollow housing comprising a single piece mounted in the control hole, and a hollow actuating piston disposed outside the housing and in the control hole to define a variable-volume hydraulic actuating piston chamber between the hollow housing and the actuating piston. The housing defines an internal actuator chamber therein and includes a hollow interior spaced away from the internal actuator chamber. The actuating piston reciprocates within the control hole relative to the hollow interior of the hollow housing between an extended position and a retracted position. The actuating piston is configured to engage the at least one exhaust valve in the extended position. The actuating piston chamber and the internal actuator chamber are fluidly connected to each other via a connecting channel in the hollow housing. The hollow interior of the hollow housing extends into the actuating piston. The compression brake control module also includes a check valve located between the connecting channel and the actuating piston chamber, and a compression brake actuator disposed in the internal actuator chamber for controlling the check valve. When the pressure of the hydraulic fluid in the actuating piston chamber exceeds the pressure of the hydraulic fluid at the supply port, the check valve hydraulically locks the actuating piston chamber. The check valve is biased closed by a bias spring. The compression brake actuator includes a control piston exposed to atmospheric pressure. The control piston is slidably mounted in the internal actuator chamber to reciprocate between an extended position and a retracted position. The compression brake control module also includes a control piston spring configured to bias the control piston toward the retracted position, wherein the control piston engages and opens the check valve solely by the biasing force of the control piston spring to unlock the actuating piston chamber and fluidly connect the actuating piston chamber to the supply port. The method of operating the exhaust rocker arm assembly includes the following steps: during the engine's braking operation mode, the hollow actuator piston is extended and the hydraulically biased reset check valve is closed by supplying pressurized hydraulic fluid from the source to the compression brake control module, and during the engine's positive power operation mode, the reset check valve is opened by stopping the supply of pressurized hydraulic fluid to the compression brake control module and allowing the hollow actuator piston to retract, thereby resetting at least one of the exhaust valves.

[0012] Other aspects of the invention, including systems, components, sub-components, units, engines, methods, etc., that form part of the invention, will become more apparent upon reading the following detailed description of exemplary embodiments. Brief description of the attached figures

[0013] Other objects and advantages of the invention will become apparent upon viewing the following description in conjunction with the accompanying drawings, in which:

[0014] Figure 1 This is a cross-sectional view of a dedicated compression-release engine brake rocker arm assembly according to a first exemplary embodiment of the present invention;

[0015] Figure 2A This is a cross-sectional view of the hydraulically actuated compression brake control module of the engine brake rocker arm assembly according to a first exemplary embodiment of the present invention in a deactivated state.

[0016] Figure 2B This is a cross-sectional view of the hydraulically actuated compression braking control module of the engine brake rocker arm assembly according to a first exemplary embodiment of the present invention in the activated state.

[0017] Figure 3 This is a cross-sectional view of a runaway compression release engine brake rocker arm assembly according to a second exemplary embodiment of the present invention;

[0018] Figure 4A This is a cross-sectional view of the hydraulically actuated compression brake control module of the runaway compression release engine brake rocker arm assembly according to a second exemplary embodiment of the present invention in a deactivated state; and

[0019] Figure 4B This is a cross-sectional view of the hydraulically actuated compression brake control module of the runaway compression release engine brake rocker arm assembly according to a second exemplary embodiment of the present invention in the activated state. Detailed Implementation

[0020] Reference will now be made in detail to the exemplary embodiments and methods of the invention illustrated in the accompanying drawings, wherein similar reference numerals throughout the drawings denote similar or corresponding parts. However, it should be noted that the invention, in its broader aspects, is not limited to the specific details, representative apparatuses and methods, and illustrative examples shown and described in relation to the exemplary embodiments and methods.

[0021] This specific implementation section is intended to be related to the appendix. Figure 1This description is to be read in conjunction with the accompanying drawings, which will be considered an integral part of the entire specification. In this specification, relative terms such as “horizontal,” “vertical,” “up,” “down,” “right,” “left,” “top,” “bottom,” “front,” “back,” “inward,” “outward,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be understood to refer to the direction described at the time or the direction shown in the figures discussed. These relative terms are for convenience of description and are not generally intended to require a specific direction. Terms relating to attachment, connection, etc., such as “connection” and “interconnection,” refer to a relationship in which structures are directly or indirectly fixed or attached together, and to movable or rigid attachments or relationships, unless otherwise explicitly described. The term “operational connection” refers to an attachment, connection, or link that allows the relevant structures to operate as intended by virtue of that relationship. The term “integral” (or “monolithic”) refers to a component manufactured as a single part, or a component consisting of independent parts fixedly (i.e., immovably) connected together. The terms “smaller” and “larger” refer to the relative dimensions of the elements and designated portions of the device of the invention. Furthermore, the word "a" used in the claims means "at least one", and the word "two" used in the claims means "at least two".

[0022] Figure 1 A compression-release engine braking system 10 for an internal combustion engine (IC) according to a first exemplary embodiment of the present invention is shown. The compression-release engine braking system 10 is a dedicated cam compression-release engine braking system (or dedicated cam engine braking system). Preferably, the internal combustion engine is a four-stroke diesel engine, typically comprising a cylinder block including one or more cylinders (not shown). Each cylinder has two intake valves (not shown), first and second exhaust valves 21 and 22, and valve trains for lifting (opening) and closing the exhaust valves 21 and 22. Each exhaust valve 21 and 22 is provided with a return spring that applies a closing force to the associated exhaust valve, causing the exhaust valve 21 and 22 to enter a closed position. The return springs (also referred to as exhaust valve springs) of the first and second exhaust valves 21 and 22 are indicated by reference numerals 31 and 32, respectively.

[0023] In this embodiment, exhaust valves 21 and 22 are substantially identical in structure. Given these similarities, and for simplicity, the following discussion will sometimes use numerals without letters to denote two substantially identical valves. For example, when referring to each exhaust valve 21 and 22 generally, numeral 2 will sometimes be used instead of listing both numerals simultaneously. It is understood that, although... Figure 1Two exhaust valves are shown, but each engine cylinder may have one or more intake valves and / or exhaust valves. The internal combustion engine is capable of both positive power operation (normal engine cycle) and engine braking operation (engine braking cycle). The compression release braking system 10 operates in compression braking (or brake open) mode during engine braking operation and in compression braking deactivated (or brake closed) mode during positive power operation.

[0024] In addition to the conventional intake and exhaust rocker arm assemblies, the dedicated cam compression release braking system 10 also includes dedicated engine brake rocker arm assemblies 12 added to each engine cylinder. These dedicated engine brake rocker arm assemblies 12 operate only one of the exhaust valves 21 and 22. Accordingly, the dedicated engine brake rocker arm assembly 12 according to a first exemplary embodiment of the invention includes a dedicated engine brake rocker arm 14 pivotally mounted around an engine brake rocker arm shaft 16 and used to open only the first exhaust valve 21 via a thru-pin (or valve bridge pin) 6 passing through the exhaust valve bridge 4. The valve bridge pin 6 is reciprocatedly mounted on the exhaust valve bridge 4 and is slidably movable relative to the exhaust valve bridge 4 to allow the first exhaust valve 21 to operate in a brake-open mode.

[0025] like Figure 1 As shown in the optimal configuration, the dedicated engine brake rocker arm 14 has two ends: a driving (first distal) end 151 for controlling the first exhaust valve 21, and a driven (second distal) end 152 adapted to contact a dedicated engine brake cam (not shown). The dedicated engine brake rocker arm 14 includes a dedicated engine brake cam follower 18 mounted on the driven end 152 of the engine brake rocker arm 14, such as... Figure 1 As best shown in the exemplary embodiment, the dedicated engine brake cam follower 18 is, for example, a cylindrical roller rotatably mounted on the driven end 152 of the engine brake rocker arm 14. The engine brake cam follower 18 is configured to contact the dedicated engine brake cam. The engine brake cam follower 18 receives input motion from the dedicated engine brake cam. Therefore, the engine brake cam follower 18 defines a camshaft interface. Alternatively, the camshaft interface can be adjusted according to engine requirements, for example, using a ball or socket for a push-rod type interface.

[0026] The engine brake rocker arm shaft 16 is configured to provide continuous lubrication to the engine brake cam follower 18 via a lubrication conduit 17 formed in the engine brake rocker arm 14.

[0027] like Figure 1As further shown, the dedicated engine brake rocker arm assembly 12 includes an independent compression brake control module (or CBCM) 22 for selectively controlling the lift and phase angle of one of the exhaust valves 21 and 22 (specifically the first exhaust valve 21). Figure 1 As shown, CBCM22 is located above the thru-pin 6. In this first exemplary embodiment, CBCM22 controls the movement of the exhaust valve primarily for, but not limited to, engine deceleration. Specifically, CBCM22 is mainly used to selectively control the lift and phase angle of the first exhaust valve 21, which functions as a braking exhaust valve. Additionally, the dedicated engine braking rocker arm assembly 12 uses CBCM22 to remove valve clearance δ from the braking valve mechanism to allow activation of engine braking, thereby opening a single exhaust valve 21 or both exhaust valves 21 and 22 at a rapid rate of increase with maximum permissible lift near top dead center (TDC) of the compression stroke. The later opening time with rapid valve lift at the beginning of the expansion stroke ensures peak cylinder pressure and rapid cylinder agitation, thus guaranteeing a high degree of engine braking deceleration power for the diesel engine.

[0028] An engine brake cam (not shown) is configured to drive (or pivot) the engine brake rocker arm 14 toward the exhaust valve bridge 4 near the TDC of the compression stroke. For example... Figure 1 As shown, CBCM22 is also used to selectively control the valve clearance (initial gap) δ of the first exhaust valve 21. The valve clearance δ is set between CBCM22 and valve bridge pin 6, preferably by adjusting CBCM22 relative to engine brake rocker arm 14. Alternatively, a corresponding valve clearance may be set between engine brake cam follower 18 and engine brake cam (not shown). The valve clearance δ is set such that when the compression release braking system 10 is in brake-off (i.e., deactivated) mode, there is sufficient clearance so that brake cam movement near TDC is not transmitted to the first exhaust valve 21.

[0029] A biasing force is applied to the engine brake rocker arm 14 to maintain the valve clearance δ and to keep the engine brake rocker arm assembly 12 in a de-energized state to avoid a "collision" between the engine brake cam and the engine brake cam follower 18. Figure 1 In the first exemplary embodiment shown, the bias spring 19 is fixedly positioned relative to the engine cylinder head (not shown) and contacts the driven end 152 of the engine brake rocker arm 14, such that the bias (or holding) force of the spring 19 keeps the dedicated engine brake cam follower 18 in contact with the dedicated engine brake cam applied to the driven end 152 of the engine brake rocker arm 14.

[0030] Alternatively, the bias spring 19 can be repositioned relative to the dedicated engine brake rocker arm 14 such that a holding force is applied to disengage the engine brake cam follower 18 from the engine brake cam, while retaining the functionality of the dedicated engine brake rocker arm assembly 12 disclosed in other ways. Furthermore, the camshaft interface can also be adjusted to suit the engine requirements, for example, by using balls or bearings for the pushrod interface. It will be apparent to those skilled in the art that the overhead engine brake cam follower 18 can be replaced with a cam-in-block pushtube assembly, and the functionality of the separately disclosed dedicated engine brake rocker arm assembly 12 will be retained.

[0031] CBCM22 is a hydraulically driven compression braking control module, such as... Figures 1-2B As shown. Alternatively, a variant of the CBCM that includes an internal spring return feature can be used, such as... Figures 4A-4B As shown.

[0032] A compressed brake fluid passage (oil pipe) 20 is provided within a dedicated engine brake rocker arm 14 to provide fluid communication between the hydraulically driven CBCM 22 and a source 80 of pressurized hydraulic fluid. Preferably, the source 80 of the pressurized hydraulic fluid is an engine oil pump (not shown) of a diesel engine. Accordingly, in this exemplary embodiment, engine lubricating oil is used as the working hydraulic fluid and is stored in a hydraulic fluid tank. It is understood that any other suitable source of pressurized hydraulic fluid and any other suitable type of fluid are within the scope of this invention. The compressed brake fluid passage 20 selectively supplies pressurized hydraulic fluid from the source to the CBCM 22 to maintain the CBCM 22 in a deactivated (or brake-off) state when no pressurized hydraulic fluid is supplied to the CBCM 22 (e.g., ...). Figure 2A (as shown) and the activation (or brake activation) state when supplying pressurized hydraulic fluid to the CBCM22 (as shown) Figure 2B Switching between (as shown). Pressurized hydraulic fluid is supplied to the CBCM 22 via the compressed brake fluid passage 20, activating the dedicated engine brake rocker arm assembly 12. This causes the CBCM 22 to extend and remain in the activated state (extended position) until the pressurized hydraulic fluid is removed (as described in US 11,149,659). With the brakes engaged, the valve clearance δ is sufficiently reduced, thereby allowing brake cam movement to be transmitted to the first exhaust valve 21 via the valve bridge pin 6.

[0033] Figure 2A and Figure 2B These are cross-sectional views of CBCM22 in its deactivated and activated states, respectively. In the first exemplary embodiment (e.g.) Figures 1-2B As shown), CBCM22 is arranged adjacent to the first exhaust valve 21 and is located above the valve bridge pin 6. Figure 2A and Figure 2B As detailed in the diagram, the CBCM22 includes a hollow housing 24 in the form of a cylindrical, one-piece hollow body, a hollow actuation piston 26 slidably mounted on the housing 24, and a retaining ring 28 mounted on the actuation piston 26. Specifically, as... Figure 2A and Figure 2B As shown in the optimal configuration, the retaining ring 28 is disposed inside the actuating piston 26 and is mounted in a groove 31 formed on the inner circumferential surface 29i of the actuating piston 26.

[0034] like Figures 1-2B As further shown, the cylindrical outer peripheral surface 25 of the housing 24 is at least partially threaded so as to be threadedly received in a cylindrical control hole 21 with threads formed in the inner portion of the drive end 151 of the engine brake rocker arm 14. Figures 1-2B (Best shown in the image). The cylindrical monolith 24 includes an integral hollow cylindrical interior 58. A lock nut 39 is provided (in... Figure 1 (Best shown in the diagram) is used to adjustably secure the housing 24 of the CBCM22 to and immovably retain it on the drive end 151 of the dedicated engine brake rocker arm 14, that is, to lock the housing 24 of the CBCM22 in place relative to the engine brake rocker arm 14. Therefore, the housing 24 of the CBCM22 is immovably, i.e., fixedly, mounted to the engine brake rocker arm 14.

[0035] More specifically, such as Figure 2A and Figure 2B As shown in detail, the actuating piston 26 is slidably mounted on the housing 24 so as to be within the non-threaded portion of the cylindrical control hole 21 in the exhaust rocker arm 14 (in Figure 2A and Figure 2B (As shown in the best example) and relative to the housing 24 of CBCM22 in the deactivated state (i.e., the retracted (or withdrawn) position) (as shown in the best example) Figure 2A (as shown) and extension position (such as) Figure 2B The housing 24 and the actuating piston 26 slide and reciprocate between each other. Therefore, the housing 24 and the actuating piston 26 define a variable volume hydraulic actuating piston chamber (or chamber) 42 within the cylindrical control hole 21 (including between the inner end face 27i of the actuating piston 26 and the housing 24).

[0036] CBCM22 has a longitudinal axis X M ,like Figure 2A and 2B As shown in the optimal diagram. The actuating piston 26 and the longitudinal axis X of CBCM22 are... M Coaxial, such as Figure 2A and Figure 2B As best shown in the diagram. The outer end (or contact) surface 27o of the actuating piston 26 engages with the brake exhaust valve 21 in its extended position via a valve bridge pin 6 reciprocally mounted to the exhaust valve bridge 4. The valve bridge pin 6 is reciprocating relative to the exhaust valve bridge 4 so that the brake exhaust valve 21 is movable relative to the exhaust valve 22 and the exhaust valve bridge 4.

[0037] The actuating piston 26 slides and reciprocates relative to the housing 24 within the non-threaded portion of the cylindrical control hole 21 in the drive end 151 of the engine brake rocker arm 14 (e.g., Figures 1-2B (As shown in the best example), in Figure 2A The retraction (or contraction) position shown and Figure 2B The piston slides back and forth between the extended positions shown. The extension limit is defined by the position of the retaining ring 28 in the actuating piston 26 and the retaining ring seat (or inner stop surface) 241 formed on the housing 24. The retaining ring 28 is configured to prevent movement of the actuating piston 26 such that the actuating piston 26 is in the extended position when the retaining ring 28 engages with the inner stop surface 241. The length of the CBCM 22 in the extended position (in Figure 2B (shown in the image) is L E The length of CBCM22 at the contraction position (in) Figure 2A (shown in the image) is L C It is less than the length L E .

[0038] exist Figure 1 In the exemplary embodiment shown, CBCM22 is fixed (i.e., non-movably attached to rocker arm 14). Specifically, CBCM22 is mounted on exhaust rocker arm 14 and adjacent to exhaust valves 21, 22. Figures 2A-2B As shown in detail, the CBCM22 includes a hollow housing in the form of a cylindrical monolith 24, which includes a one-piece hollow cylindrical interior 58. The cylindrical monolith 24 also defines a cylindrical internal actuator cavity 23.

[0039] The CBCM22 further includes a hydraulic compression brake actuator 30 mounted within an actuator cavity 23 of the housing 24. The compression brake actuator 30 further includes a control piston 32 slidably mounted within the housing 24, an end cap 62, and a control piston spring 34 disposed within the housing 24 and located between the control piston 32 and the end cap 62, biasing the control piston 32 toward the actuating piston 26. Figures 2A-2B As shown, the control piston 32 is integrally formed with the control piston pin 33 extending into the cylindrical interior 58 of the hollow housing 24. The control piston 32 is slidably positioned within the housing 24. Figure 2A The extended positions shown and Figure 2BThe piston reciprocates between the retracted and extended positions, and is biased toward the extended position by the control piston spring 34. The retraction of the control piston 32 is limited by the position of the end cap 62 relative to 24, while the extension of the control piston 32 is limited by the position of the control piston seat 242 within the housing 24. The actuating piston 26 is in the retracted position when its inner end face 27i engages with the bottom surface 60 of the cylindrical interior 58 of the hollow housing 24.

[0040] The inner end (or bottom) surface 66 of the control piston 32 within the housing 24. B A variable-volume actuator chamber 64 is defined within the innermost portion of the cylindrical actuator cavity 23 between the control piston 32 and the control piston seat 242. When the control piston 32 is in the extended position, the bottom surface 66 of the control piston 32... B It can engage with the control piston seat 242 of the control piston 32, such as Figure 2A As shown. When the control piston 32 is in the retracted position, the outer end (or top) surface 66 of the control piston 32... T It can engage with the end cap 62 of the housing 24. A control piston spring 34 extends between the control piston 32 and the end cap 62, causing the control piston 32 to deflect downwards into a retracted position. The control piston 32 is drilled to form a vent chamber 68 between the control piston 32 and the end cap 62 to receive the control piston spring 34. The vent chamber 68 is subjected to atmospheric pressure through at least one vent 70 on the end cap 62, which exposes the outer end (or top) face 66 of the control piston 32 to atmospheric pressure. T Exposed to atmospheric pressure. The control piston 32 is adapted to reciprocate between the control piston seat 242 and the end cap 62 of the housing 24.

[0041] The CBCM22 also includes a reset check valve (i.e., one-way) 35, which includes a valve member 36, preferably in the form of a ball member, and a biasing valve spring 38. The valve member 36 is biased toward a valve seat 243 in the housing 24 by the biasing valve spring 38. The CBCM22 also includes a supply (or inlet) port 44 formed within the housing 24. Figure 1 As shown, the supply port 44 is fluidly connected to the brake fluid passage 20 in the engine brake rocker arm 14 to supply pressurized hydraulic fluid from a source of pressurized hydraulic fluid to the actuating piston chamber 42 via the control piston passage 46. Therefore, pressurized hydraulic fluid can flow into the inlet port 44 in the housing 24 and enter the internal actuator chamber 23 and the actuating piston chamber 42 via the control piston passage 46, causing the actuating piston 26 to extend from the housing 24.

[0042] When CBCM22 is deactivated, the control piston 32 of the compression brake actuator 30 selectively engages with the valve member 36 of the reset check valve 35 to unlock the actuation piston chamber 42 (e.g., Figure 2A(As shown) and fluidly connects the actuated piston chamber 42 to the supply port 44 of pressurized hydraulic fluid. When activated, the control piston 32 disengages from the valve member 36 to lock the actuated piston chamber 42 and fluidly disconnects the actuated piston chamber 42 from the supply port 44 of pressurized hydraulic fluid, as shown. Figure 2B The best result is shown in the middle.

[0043] According to this exemplary embodiment of the invention, the CBCM22 further includes a hydraulic seal (or sealing device) 40 to limit hydraulic leakage and minimize hydraulic compliance during engine braking. Figure 2A and Figure 2B As shown, a hydraulic seal 40 is mounted on the smooth outer peripheral surface 29o of the actuating piston 26. The hydraulic seal 40 is disposed between the actuating piston 26 and the cylindrical control hole 21 of the exhaust rocker arm 14 to eliminate piston-to-hole leakage of pressurized hydraulic fluid. The seal 40 eliminates leakage from the cylindrical control hole 21 of the exhaust rocker arm 14 and holds the actuating piston 26 in the retracted position without the need for an additional return spring. Figure 1 As shown, CBCM22 is threadedly engaged with the drive end 151 of the engine brake rocker arm 14. As... Figure 2B As shown in the best embodiment, a variable volumetric actuation piston chamber 42 is defined between the engine brake rocker arm 14, the housing 24 and the actuation piston 26.

[0044] The actuating piston chamber 42 in the actuating piston 26 and the internal actuator chamber 23 in the hollow housing 24 are fluidly connected to each other through a connecting channel 59 in the hollow cylindrical interior 58 of the hollow housing 24. Figures 2A-2B As shown, the control piston pin 33 of the control piston 32 extends into the connection channel 59 in the hollow cylindrical interior 58 of the hollow housing 24, toward the valve component 36 of the reset check valve 35.

[0045] In the deactivated state (i.e., depressurized state) of CBCM22, the ball valve component 36 is prevented from contacting the valve seat 243 in the housing 24 by the control piston pin 33. The control piston pin 33 extends into the cylindrical interior 58 of the hollow housing 24, toward the valve component 36 of the reset check valve 35.

[0046] Due to the presence of the hydraulic seal 40, the actuating piston 26 can also extend due to the force of the bias valve spring 38 or due to road vibrations. If the fluid pressure in the supply port 44 is insufficient to raise the control piston 32 to the retracted position, then the actuating piston 26 will not be able to withstand a force greater than the force required to extend it. Therefore, any significant force applied to the outer end face 27o of the actuating piston 26 will cause the actuating piston 32 to retract.

[0047] When CBCM22 is in the off-state, the frictional force from the hydraulic seal 40 acts on... Figure 2A and Figure 2B The actuating piston 26 of the CBCM22 is movably mounted on the rocker arm 14, providing additional holding force to avoid “collision” with the valve bridge 4.

[0048] CBCM22 is activated by increasing the hydraulic pressure in supply port 44 to a level that causes control piston 32 to reach its retracted position, such as Figure 2B As shown. This brings the valve member 36 into contact with the valve seat 243, forming a one-way (check valve) 35 in the actuated piston chamber 42. Any force applied to the contact surface 27o of the actuated piston 26 is supported by the hydraulic pressure within the actuated piston chamber 42.

[0049] CBCM22 is deactivated by reducing the hydraulic pressure in supply port 44 to a level that allows control piston 32 to move to the extended position, as... Figure 2A As shown. Before the valve member 36 is lifted away from the valve seat 243, the force must be removed from the contact surface 27o of the actuating piston 26. Once the valve member 36 is lifted and the control piston 32 is fully extended, the actuating piston 26 can no longer support a significant force. The activation and deactivation of the control module 22 is typically achieved via a switch in the operator's cab, which also shuts off the engine's fuel supply.

[0050] The operation of the exhaust rocker arm assembly 12 for operating at least one exhaust valve 21 of the internal combustion engine during compression-release engine braking operation is as follows. First, during the braking operation mode of the internal combustion engine, when pressurized hydraulic fluid is supplied from the compression brake fluid passage 20 to the CBCM 22 to extend the hollow actuated piston 26 and hydraulically activate the compression brake actuator 30, the reset check valve 35 is biased closed. Next, during the valve braking lift of at least one exhaust valve 21, the reset check valve 35 is hydraulically biased closed. Then, the pressurized hydraulic fluid supply from the source 80 to the CBCM 22 is stopped. As a result, the reset check valve 35 is biased open, allowing the hollow actuated piston 26 to retract in the positive power operation mode of the engine. Therefore, at least one exhaust valve 21 is reset by opening the reset check valve 35 and releasing hydraulic fluid from the actuated piston chamber 42 to close the at least one exhaust valve 21.

[0051] Figure 3 A compression release brake 110 according to a second exemplary embodiment of the present invention is shown, which is provided to an internal combustion engine (IC), such as a diesel engine. Components that do not change compared to the first exemplary embodiment are labeled with the same reference numerals. Figures 1-2BComponents that function in the same manner as those in the first exemplary embodiment shown are indicated by the same reference numerals, some of which are marked with 100. Sometimes, detailed description is unnecessary because the reader can easily perceive the similarity between the corresponding components in the two embodiments.

[0052] The compression release brake 110 is a lostmotion compression-release engine brake system (or lostmotion exhaust rocker arm engine brake system) with automatic hydraulic adjustment and reset function. The term "lostmotion" refers to a rocker arm brake that adds an extra small lift profile to the exhaust camlobe, opening one or more exhaust valves near the TDC of the compression stroke when excess exhaust valve clearance is removed from the valve mechanism. Preferably, the internal combustion engine is a four-stroke diesel engine, which typically includes a cylinder block comprising one or more cylinders (not shown). Each cylinder has two intake valves (not shown), a first (or brake) and a second exhaust valve 21 and 22, and a valve mechanism for lifting (opening) and closing the exhaust valves 21 and 22. Each exhaust valve 21 and 22 has a return spring that applies a closing force to the exhaust valve, causing the exhaust valve 21 and 22 to enter the closed position. The return springs (also referred to as exhaust valve springs) of the first and second exhaust valves 21 and 22 are indicated by reference numerals 31 and 32, respectively.

[0053] In this embodiment, exhaust valves 21 and 22 are substantially identical in structure. Given these similarities, and for simplicity, the following discussion will sometimes use numerals without letters to denote two substantially identical valves. For example, when referring to each exhaust valve 21 and 22 generally, numeral 2 will sometimes be used instead of listing both numerals simultaneously. It is understood that, although... Figure 3 The diagram shows two exhaust valves, but each engine cylinder may have one or more intake valves and / or exhaust valves.

[0054] The internal combustion engine is capable of performing positive power operation (normal engine cycle) and engine braking operation (engine braking cycle). The compression release braking system 110 operates in compression braking (or brake open) mode during engine braking operation and in compression braking deactivated (or brake closed) mode during positive power operation.

[0055] The runaway compression release braking system 110 includes a conventional intake rocker arm assembly (not shown) for operating one or more intake valves, and a runaway exhaust rocker arm assembly 112 for operating at least one of a first exhaust valve 21 and a second exhaust valve 22. Furthermore, the exhaust rocker arm assembly 112 has an automatic hydraulic adjustment and reset function, as described herein. The runaway exhaust rocker arm assembly 112 includes a runaway exhaust rocker arm 114, which is pivotally mounted for movement about an engine rocker arm shaft 116 to open the first and second exhaust valves 21 and 22 via an exhaust valve bridge 104. The rocker arm shaft 116 allows the exhaust rocker arm 114 to transmit camshaft motion to the exhaust valves 21 and 22 via the exhaust valve bridge 104, i.e., to move one or both exhaust valves 21 and 22 to the open position, which is returned to the closed position by exhaust valve springs 31 and 32. Figure 3 As shown, the deactivated exhaust rocker arm 114 has two ends: a driving (first distal) end 1151 for controlling exhaust valves 21 and 22, and a driven (second distal) end 1152 adapted to engage a dedicated engine brake cam (not shown). Figure 3 As shown, the deactivated exhaust rocker arm 114 includes an exhaust cam follower 118 mounted on the driven end 1152 of the deactivated exhaust rocker arm 114. The exhaust cam follower 118 is, for example, a cylindrical roller rotatably mounted on the driven end 1152 of the exhaust rocker arm 114. The exhaust cam follower 118 contacts an exhaust cam (not shown). The exhaust cam follower 118 receives input motion from the exhaust cam. Therefore, the exhaust cam follower 118 defines a camshaft interface. The rocker arm shaft 116 provides continuous lubrication to the exhaust cam follower 118 through a lubrication conduit 117 formed in the exhaust rocker arm 114. Alternatively, the camshaft interface can be adjusted according to engine requirements, for example, using a ball or bearing for a pushrod type interface.

[0056] like Figure 3 As further shown, the rocker arm assembly 112 includes an independent compression brake control module (or CBCM) 122 for selectively controlling the lift and phase angle of one or both exhaust valves 21 and 22, and a sliderscrew assembly 150. Figure 3 As shown, the CBCM122 is positioned above the exhaust valve bridge 104 and the brake exhaust valve 21, while the slider screw assembly 150 is located in the center of the valve bridge 104. The rocker arm shaft 116 selectively delivers pressurized hydraulic fluid to the CBCM122 through a brake fluid passage 120 formed in the exhaust rocker arm 114, and continuously delivers lubrication to the slider screw assembly 150 through a lubrication conduit 148 formed in the exhaust rocker arm 114.

[0057] An exhaust cam (not shown) pivots the exhaust rocker arm 114 toward the valve bridge 104 to open and close exhaust valves 21 and 22 during the normal exhaust stroke. After the normal exhaust stroke ends, the exhaust cam profile moves away from the exhaust cam follower 118, thereby allowing the exhaust cam follower 118 to move (rotate) away from the valve bridge 104. The slider screw assembly 150 extends under the force of the slider spring 152 to pivot the exhaust rocker arm 114 toward the exhaust cam, maintaining its contact with the exhaust cam as the exhaust cam follower 118 moves away.

[0058] The exhaust cam drives the exhaust rocker arm 114 toward the valve bridge 104 near the TDC of the compression stroke. This oscillating motion of the exhaust rocker arm 114 is not transmitted to the exhaust valves 21 and 22 during normal (or positive power) engine operation (or the brake-off mode of the loss-compression release engine braking system 110), that is, it is “lost” to the valves.

[0059] The loss-of-compression release engine braking system 110 is actuated by supplying pressurized hydraulic fluid to the brake fluid passage 120 and CBCM 122. The pressurized fluid causes CBCM 122 to extend during the “out” portion of the cycle, i.e., when the drive end 1151 of the exhaust rocker arm 114 with CBCM 122 pivots away from the exhaust valve bridge 104. CBCM 122 maintains this extended position until the pressurized fluid is removed (as described in US11,149,659). CBCM 122 extends far enough that the “lost” motion is subsequently “found” by the brake exhaust valve 21, and the brake exhaust valve 21 opens near the TDC compression stroke.

[0060] Alternatively, the overhead exhaust cam follower 118 can be replaced by a cam-in-block pushtube assembly, while retaining the functionality of the otherwise disclosed loss-compression release engine braking system 110. It is also evident that, as Figure 3 As shown, the valve bridge pin of valve bridge 104 can be used to control the contact pressure of the interface between brake exhaust valve 21, valve bridge 104 and CBCM 122 without affecting the disclosed function.

[0061] Figure 4A and Figure 4B This is a cross-sectional view of the hydraulically driven CBCM122 in the second exemplary embodiment, in both the deactivated and activated states.

[0062] CBCM122 includes a reset check valve (i.e., one-way) 135, which includes a valve member 136, preferably in the form of a spherical member, and a bias valve spring 138. CBCM122 also includes a hollow housing 124 in the form of a cylindrical one-piece hollow body, an actuating piston 126 slidably mounted on the housing 124, and a retaining ring 128 mounted on the actuating piston 126.

[0063] Figure 4A and Figure 4B An actuated piston biasing mechanism is shown, comprising an actuated piston biasing spring 153, an actuated biasing washer 154, and an actuated biasing retaining ring 156 arranged in an actuated piston chamber 142. A cylindrical one-piece housing 124 receives the actuated biasing washer 154 and the actuated biasing retaining ring 156, such that the actuated piston biasing spring 153 is disposed therebetween. The actuated piston 126 is biased to an extended position under the action of the actuated piston biasing spring 153. The extension limit of the actuated piston 126 is defined by the positions of the retaining ring 128 mounted on the actuated piston 126, the actuated biasing washer 154 in the actuated piston 126, and the washer ring seat 155 in the housing 124. In the deactivated state, the biasing valve spring 138 creates a minimum force threshold that must be overcome to move the actuated piston 126 to a retracted position (e.g., ...). Figure 4A (As shown), it resists extension caused by low hydraulic pressure of the hydraulic fluid in the brake fluid passage 120, movement of the exhaust rocker arm 114, and external vibration.

[0064] The foregoing description of preferred embodiments of the invention is intended to illustrate it in accordance with patent regulations. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations can be made in accordance with the foregoing teachings. The embodiments disclosed herein were chosen to best illustrate the principles of the invention and its practical application, thereby enabling those skilled in the art to best utilize the invention in various embodiments and to make various modifications according to the particular intended use, provided that the principles set forth herein are followed. Therefore, modifications can be made to the invention without departing from its intent and scope. The scope of the invention is also intended to be defined by the appended claims.

Claims

1. An exhaust rocker arm assembly for operating at least one exhaust valve of an internal combustion engine during compression-release engine braking operation, the exhaust rocker arm assembly comprising: Exhaust rocker arm; and An independent compression braking control module is mounted on the exhaust rocker arm and operatively connected to the at least one exhaust valve to control the lift and phase angle of the at least one exhaust valve. When the compression release engine braking operation is performed, the compression braking control module keeps the at least one exhaust valve open during the compression stroke of the internal combustion engine. The compression braking control module includes: A hollow housing comprising a single piece mounted in the exhaust rocker arm, the housing defining an internal actuator cavity and including a hollow interior remote from the internal actuator cavity; A hollow actuating piston is disposed outside the housing and mounted in the exhaust rocker arm to receive the interior. The actuating piston defines a variable-volume hydraulic actuating piston chamber between the housing and the actuating piston. The actuating piston reciprocates relative to the interior between an extended position and a retracted position. In the extended position, the actuating piston is configured to engage with the at least one exhaust valve. A connection channel is arranged in the housing to fluidly connect the actuating piston chamber to the internal actuator chamber; A reset check valve is disposed between the connection channel and the actuated piston chamber. The reset check valve is configured to hydraulically lock the actuated piston chamber when the pressure of the hydraulic fluid in the actuated piston chamber exceeds the pressure of the hydraulic fluid in the supply port formed in the housing. The reset check valve is biased closed via a bias spring. A compression brake actuator, slidably disposed within the internal actuator cavity to control the reset check valve, the compression brake actuator including a control piston exposed to atmospheric pressure, the control piston being configured to reciprocate between an extended position and a retracted position; and A control piston spring biases the control piston toward the extended position, in which the control piston engages and opens the reset check valve only via the biasing force of the control piston spring, so as to unlock the actuation piston chamber and fluidly connect the actuation piston chamber to the supply port; The actuating piston includes an inner circumferential surface defining a groove and a retaining ring mounted to the groove. The interior includes the outer peripheral surface that defines the inner stop surface, and The retaining ring is configured to engage the inner stop surface so that when the retaining ring engages with the inner stop surface, it prevents the actuating piston from moving relative to the housing when the actuating piston reaches the extended position.

2. The exhaust rocker arm assembly according to claim 1, wherein, The supply port is fluidly connected to a compression braking fluid passage formed in the exhaust rocker arm, and, The supply port is configured to supply pressurized hydraulic fluid to the actuating piston chamber via the connection channel.

3. The exhaust rocker arm assembly according to claim 1, wherein, The exhaust rocker arm includes a control port configured to receive the actuated piston to define the hydraulically actuated piston chamber, and, The actuating piston reciprocates within the control hole.

4. The exhaust rocker arm assembly according to claim 3, wherein, The single piece includes a partially threaded outer cylindrical surface configured to engage with the control hole.

5. The exhaust rocker arm assembly according to claim 3, wherein, The actuating piston also includes an external seal and a smooth outer surface configured to engage with, seal, and reciprocate within the control orifice.

6. The exhaust rocker arm assembly according to claim 1, wherein, The interior separates the internal actuator cavity from the actuation piston cavity, and, The connection channel is formed within the interior.

7. The exhaust rocker arm assembly according to claim 1, wherein, The control piston includes a bottom surface exposed to hydraulic fluid and a top surface exposed to atmospheric pressure.

8. The exhaust rocker arm assembly according to claim 7, wherein, The actuator cavity is sealed with an end cap that includes an exhaust port.

9. The exhaust rocker arm assembly according to claim 1, wherein, The actuating piston includes: The bottom surface, configured to engage the control piston seat when the control piston is in the extended position, and The top surface is configured to close the internal actuator cavity when the control piston is in the retracted position.

10. The exhaust rocker arm assembly according to claim 1, wherein, The control piston spring is disposed within the housing, located between the control piston and the end cap.

11. The exhaust rocker arm assembly according to claim 1, wherein, The exhaust rocker arm is a dedicated engine brake rocker arm that is pivotally mounted about an engine brake rocker arm axis and is configured to open the at least one exhaust valve only via a valve bridge pin that passes through the exhaust valve bridge.

12. The exhaust rocker arm assembly according to claim 1, wherein, The exhaust rocker arm is a stalled exhaust rocker arm that is pivotally mounted about an engine rocker arm axis and is configured to open the at least one exhaust valve via an exhaust valve bridge.

13. The exhaust rocker arm assembly according to claim 1, wherein, The actuating piston includes an inner end face and an outer end face, the outer end face being configured to engage with the at least one exhaust valve when the actuating piston is in an extended position.

14. A runaway exhaust rocker arm assembly for operating at least one exhaust valve of an internal combustion engine during compression-release engine braking operation, the runaway exhaust rocker arm assembly comprising: Loss of exhaust rocker arm; A slider screw assembly and an independent compression brake control module, each of which is mounted to the unresponsive exhaust rocker arm and operatively connected to at least one exhaust valve via an exhaust valve bridge to control the lift and phase angle of the at least one exhaust valve, wherein, when the compression release engine brake operation is performed, the compression brake control module keeps the at least one exhaust valve open during the compression stroke of the internal combustion engine, the compression brake control module comprising: A hollow housing comprising a single piece mounted in the disengaged exhaust rocker arm, the housing defining an internal actuator cavity and a hollow interior remote from the internal actuator cavity; A hollow actuating piston is disposed outside the housing and mounted in the deactivated exhaust rocker arm, the hollow actuating piston defining a variable volume hydraulic actuating piston chamber between the housing and the actuating piston, the actuating piston reciprocating between an extended position and a retracted position relative to the interior, in the extended position the actuating piston is configured to engage with the at least one exhaust valve; A connection channel is arranged in the housing to fluidly connect the actuating piston chamber to the internal actuator chamber; An actuating piston biasing spring is disposed within the actuating piston chamber and configured to bias the actuating piston toward its extended position. A reset check valve is disposed between the connection channel and the actuated piston chamber. The reset check valve is configured to hydraulically lock the actuated piston chamber when the pressure of the hydraulic fluid in the actuated piston chamber exceeds the pressure of the hydraulic fluid in the supply port formed in the housing. The reset check valve is biased closed via a bias spring. A compression brake actuator, slidably disposed within the internal actuator cavity to control the reset check valve, the compression brake actuator including a control piston exposed to atmospheric pressure, the control piston being configured to reciprocate between an extended position and a retracted position; and A control piston spring biases the control piston toward the extended position, in which the control piston engages and opens the reset check valve only via the biasing force of the control piston spring, so as to unlock the actuation piston chamber and fluidly connect the actuation piston chamber to the supply port; The actuating piston includes an inner circumferential surface defining a groove and a retaining ring mounted to the groove. The interior includes the outer peripheral surface that defines the inner stop surface, and The retaining ring is configured to engage the inner stop surface so that when the retaining ring engages with the inner stop surface, it prevents the actuating piston from moving relative to the housing when the actuating piston reaches the extended position.

15. The exhaust rocker arm assembly according to claim 14, wherein, The slider screw assembly is centered above the valve bridge.

16. The exhaust rocker arm assembly according to claim 14, wherein, Both the slider screw assembly and the independent compression brake control module are mounted to the first distal end of the stalled exhaust rocker arm.

17. A method for operating the exhaust rocker arm assembly according to any one of claims 1-13, the method comprising: During engine braking operation mode, pressurized hydraulic fluid is supplied from the compression brake fluid passage to the compression brake control module to extend the actuation piston and hydraulically bias the reset check valve closed. and During the positive power operation mode of the engine, the supply of pressurized hydraulic fluid to the compression brake control module is stopped in order to open the reset check valve and thus retract the actuating piston.

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