An engine brake rocker arm assembly

Abstract

An engine brake rocker arm assembly (RA) including a rocker arm (RA), a castellation assembly (1) and a first hydraulic actuator (70) arranged to rotate at least an element (JK) of the castellation assembly (1), wherein the castellation assembly (1) includes a first element (A) comprising a first end (A1) protruding outside the rocker arm, at the upper portion (URA) of the rocker arm, a second element (B), including a first end (B1) protruding outside the rocker arm to contact an exhaust valve (EV) and a second end (B2) defining a seat (BS) for the second end (A2) of the first element (A), a jacket element (JK), having tubular shape, arranged to contain said second end of both said first and second elements (A, B), wherein the second element is provided with radial teeth (RT) and the jacket element is provided of axial teeth (AT) arranged to assume a first configuration and a second configuration, an oil channel (OC) arranged within the rocker arm to fill both the first (70) and said second hydraulic actuator.

Description

[0001] AN ENGINE BRAKE ROCKER ARM ASSEMBLY

[0002] Field of the invention

[0003] The present invention relates to the field of engine brake actuation systems, in the field of medium and heavy- duty vehicles .

[0004] Description of the prior art

[0005] Compression engine brakes can be used as auxiliary brakes, in addition to wheel brakes, on relatively large vehicles, for example trucks, powered by heavy or medium duty diesel engines. During engine brake operation, the engine is not fueled and a compression engine braking system is arranged, to provide an additional opening of an engine cylinder's exhaust valve when the piston in that cylinder is near a top-dead-center position of its compression stroke so that compressed air can be released through the exhaust valve.

[0006] This causes that the air trapped in the cylinder cannot return the compression energy accumulated during compression. Thus, the engine works as an air compressor and the torque consumed slows the vehicle.

[0007] In a typical valve train assembly used with a compression engine brake, the exhaust valve is actuated by a rocker arm which engages the exhaust valve by means of a valve bridge. The rocker arm rocks in response to a cam on a rotating cam shaft and presses down on the valve bridge which in turn presses down on the exhaust valves to open them .

[0008] In several rocker arm assembly, an oil circuit pressuri zes a mechanism which pushes selectively an exhaust valve during engine brake .

[0009] EATON INTELLIGENT POWER LTD has developed several solutions , commercially available on the market .

[0010] The Eaton® solution is mainly based on a castellation assembly as disclosed in WO2022248082A1 and WO2019133658 .

[0011] Here an actuator 70 is arranged to rotate a first castellation member 22 in such a way that its axial teeth 100 contact the axial teeth 104 of a second castellation member 20 or the valleys 106 between the teeth 104 , while the teeth 104 of the second castel lation member contact the valleys 102 of the first castellation member .

[0012] The first castellation is rotatably mounted on a passing through bore of the rocker arm .

[0013] In the first case , as disclosed in figure lb, the two castellation members develop the maximal extension of the shaft so as to activate the exhaust valve , while in the second case , the two castellation members 22 , 20 are mutually collapsed . When the castellation is in its maximal extension, it forces the foot 21 to stably protrude downwards to push down the exhaust valve to reali ze the engine brake operation .

[0014] In the last period, EATON developed a new solution disclosed in US 11428127B2 . Here , there are three castellation members mounted on a shaft .

[0015] The third castellation member biases the first and second castellation members apart . The engine brake rocker arm assembly selectively opens first and second exhaust valves and includes an exhaust rocker arm configured to rotate about the rocker shaft , an engine brake capsule assembly movable between a locked position configured to perform an engine braking operation, and an unlocked position that does not perform the engine braking operation, and a hydraulically controlled actuator assembly configured to selectively move the engine brake capsule assembly between the first and second configurations .

[0016] The actuator assembly includes a pin arranged to rotate the first castellation member of the engine brake capsule assembly . In the fired condition, namely when the engine brake operation is deactivated, the castellation shaft is configured to slide with the nut for the lash adj ustment . Figures la and lb of the prior art , corresponding to figures 3a of US 11428127B2 and figure 6B of WO2019133658 , disclose two configurations of the castellation with respect to the rocker arm .

[0017] Here the engine brake capsule can be af fixed to the same rocker arm operating the valve bridge as disclosed in WO2019133658 , or can be af fixed to a secondary rocker arm as in W02021164950 .

[0018] Here , the main problem is in the fact that the nut 23 arranged to adj ust the position of the first element of the castellation assembly, often named as travel stop, impacts on the seat of the capsule in each swinging operation of the rocker arm in the fired condition .

[0019] These impacts produce noise and lead to the damaging of the assembly rocker / capsule .

[0020] Therefore , it is possible to summari ze the present context as an engine brake capsule assembly comprising at least two castellation members provided with axial teeth . One of the castellation members is arranged to rotate in such a way the axial teeth face the axial teeth of the other castellation member or the corresponding valleys . Therefore , the two possible configurations are " tooth-to- tooth" or " tooth-to-valley" . The actuator is arranged to tangentially contact and rotate the rotating castellation member to control the angular position of it with respect to the other castellation member . The castellation members are arranged on a shaft provided of a nut of the lash adj ustment screw . In fired operating conditions , the nut alternately departs and approaches the rocker arm, due to the fact that the castellation capsule is collapsed . This alternate movement leads to producing impacts , noise and damages .

[0021] US 11428127B2 and WO2021164950 are herewith included by reference .

[0022] It is clear, looking at the prior art figures , that the castellation shaft is made of one single piece .

[0023] Summary of the invention

[0024] The main obj ect o f the present invention is to overcome the above problems / drawbacks in the solution proposed and commerciali zed by EATON® .

[0025] The main principle of the invention is the implementation of a castellation assembly comprising :

[0026] - a first element arranged to protrude upwards from the rocker arm, to support the lash adj ustment nut ,

[0027] - a second element arranged to protrude downwards from the rocker arm, comprising a foot arranged to contact , in engine brake operation, an exhaust valve and defining a first castellation member ;

[0028] - a j acket element , arranged to contain both the first and second elements and defining a second castellation member . The second element is equipped with radial teeth, while the j acket element is equipped with axial teeth complementary to the radial teeth of the second element .

[0029] It should be noted that there is not a shaft in a single piece , from the lash adj ustment screw to the foot .

[0030] In contrast , the above second element and the j acket element , when in the " tooth-to-tooth" configuration, define a rigid body capable to push the exhaust valve , while in the " tooth-to-valley" configuration, the second element is collapsed on the first element and within the j acket element due to the ef fect of a raising spring .

[0031] The raising spring is arranged to maintain the second element retracted, against the first element such as not to contact the exhaust valve .

[0032] An oil channel is arranged to communicate with the housing defined by the j acket in order to permit the pressuri zation of the cavity within the j acket element , so as to exert an opposite action with respect to the raising spring, such as to extend the castellation assembly .

[0033] An actuator, as those disclosed in prior art is arranged to rotate the j acket element such as to induce the transition from the tooth- to-valley configuration to the tooth-to- tooth configuration .

[0034] When the above oil channel and the actuator are pressuri zed, first the castellation assembly extends , then the actuator lock the extended configuration by rotating the j acket element in the tooth-to-tooth configuration .

[0035] When the oil pressuri zation ends , first the return spring of the actuator forces the rotation of the j acket element in the opposite direction, such as to induce the transition form the tooth-to-tooth configuration to the tooth-to- valley configuration . Then, the raising spring retracts the second element of the castellation assembly .

[0036] From the above description, it is clear that the j acket element behave as cylinder and the second element of the castellation assembly acts as a piston reciprocating the cylinder, as an actuator .

[0037] These and further obj ects are achieved by means of the attached claims , which describe preferred embodiments of the invention, forming an integral part of the present description .

[0038] Brief description of the drawings

[0039] The invention will become fully clear from the following detailed description, given by way of a mere exempli fying and non limiting example , to be read with reference to the attached drawing figures, wherein:

[0040] Figs, la and lb of the prior art disclose an example of brake, switchable, capsule from EATON® in two opposites conditions while the engine is operated not in braking mode, namely it is fired or dragged;

[0041] Fig. 2 discloses an overview figure of a preferred implementation of the present invention with elements disclosed in transparency, according to a first operating condition;

[0042] Fig. 3 discloses a magnified portion of figure 2;

[0043] Fig. 4 discloses a perspective view of a portion of the implementation of figure 2, with elements disclosed in transparency;

[0044] Fig. 4a discloses a top view of the same portion of figure 4 according to the first operating condition;

[0045] Fig. 5 discloses the same magnified portion of figure 3 in a second, different, operating condition;

[0046] Fig. 5a discloses the top view of the same portion of figure 4 according to the second operating condition.

[0047] The same reference numerals and letters in the figures designate the same or functionally equivalent parts.

[0048] According to the present invention, the term "second element" does not imply the presence of a "first element", first, second, etc.. are used only for improving the clarity of the description and they should not be interpreted in a limiting way .

[0049] Detailed description of the preferred embodiments

[0050] As disclosed above , the present invention aims at solving the impacts between the nut 23 of the lash adj ustment screw, also named "travel stop" , against the upper portion URA of the rocker arm RA.

[0051] In FIGS . 1A and IB of the prior art , a first castellation device 1 constitutes a mechanical capsule comprising an annular shroud 80 coupled to a rack 75 of the actuator 70 . This mechanical capsule can be drop-in assembled in a capsule bore 17 ( see fig . 1 ) . A bore end 171 comprises a lash bore 172 through hole through which the shaft 20 can slide .

[0052] Here , according to the present invention, see f igure 3 , similarly to the shaft 20 , the first element A of the castellation assembly has a first end Al protruding outside the rocker arm, at the upper portion URA of the rocker arm; on the first end, the nut 23 is screwed and a second end A2 , inside the bore 17 .

[0053] The bore 17 is named as "capsule bore" because the castellation assembly can be assembled outside the rocker arm as capsule , and swapped inside the bore 17 . The first element A has a generally elongate shape , and more in particular at least the first end has a cyl indrical shape , threaded to accommodate the nut 23 .

[0054] It should be noted that , only the first end of the first element A protrude outside the bore 17 .

[0055] The castellation assembly includes a second element B, which is distinct and separated by the first element A; in addition it includes : a first end Bl protruding outside the rocker arm, at a lower portion of the rocker arm, in operation towards an exhaust valve EV; a second end B2 , inside the bore 17 .

[0056] In other words , the first end Bl protrudes outside in an opposite direction with respect to the first end Al of the first element A, thus the first A and second element B of the castellation assembly 1 are circa coaxial between each other, in such a way to define the above shaft 20 of the prior art , but in two separate pieces .

[0057] Therefore , there is not a shaft in a single piece , from the lash adj ustment screw to the foot in contrast with the prior art .

[0058] The second end B2 of the second element B is preferably shaped as a seat BS to accommodate the second end A2 of the first element A. In addition, the outer surface of the second end B2 of the second element B is designed to define a piston, better described below .

[0059] The castellation assembly, in addition, includes a j acket element JK, a sort of tubular element , arranged to envelope the second ends o f the first and second elements A, B . Also the j acket element is , thus , coaxial with the first and second elements A, B .

[0060] More in particular, the j acket element JK behaves as a cylinder, while the second end B2 of the second element B behaves as a piston reciprocating the cylinder .

[0061] The j acket element , in turn, has a first end JK1 , seated on the bore end 171 and a second end JK2 , opposite to the first one .

[0062] Both the second element B and the j acket element JK are provided of castellation teeth : the second end JK2 of the j acket element JK has axial teeth, while an intermediate portion B12 of the second element B is provided with radial teeth RT .

[0063] When the teeth of the second element B are in the tooth-to- tooth configuration with the teeth of the j acket element , the j acket element maintain the second element B in the extracted condition in order to contact and push the exhaust valve EV . A raising spring RS is arranged to maintain the second element retracted, against the first element such as not to contact the exhaust valve , when said teeth are in the configuration tooth-to-valley .

[0064] More in particular, the raising spring maintain the seat BS of the second element biased against the second end A2 of the first element A. Thus , the nut 23 permits to adj ust the position of the second element B in the retracted condition .

[0065] An oil channel OC is arranged in the rocker arm body in order to fill the seat BS defined in the second element B . The pressuri zation of the seat BS forces the piston defined by the second end B2 of the second element B to move downwards against the biasing ef fect of the raising spring RS .

[0066] Figure 4 discloses a perspective view of a portion of another example of the invention . Figure 4 helps to recogni ze the radial teeth RT of the second element B of the castellation assembly and the axial teeth AT of the j acket element JK .

[0067] Figure 4 discloses , in addition, also the actuator 70 . The actuator 70 is per se known, being implemented by EATON .

[0068] It defines a "rack and pinion" type arrangement such as an axial movement of the actuator forces one of the castellation members to rotate . Being the EATON product already on the market and well disclosed in several patents , no further details are needed .

[0069] According to figure 4a it is clear that the actuator includes a screw SKR arranged to mesh a rack RK defined in the outer surface of the j acket JK . A return spring RTS is arranged to push the screw SKR toward a predetermined position, on the left of the sheet , such that the teeth of the j acket element JK are interspersed with the teeth of the second element B and the raising spring RS can bias the element B against the element A.

[0070] When a solenoid valve (no disclosed) is activated, both the seat BS of the second element B, behaving as a cylinder, and the actuator 70 are pressuri zed, thus , the element B is forced to move outward with respect to the capsule bore 17 , see Figure 5 , and the screw SKR is forced to move against the return spring RTS , toward the right in the sheet , see Figure 5a .

[0071] The activation of the actuator, after the outward motion of the second element B, permits the reaching of the tooth-to- tooth configuration, that corresponds to the engine brake activation .

[0072] The raising spring is preferably interposed between a radial expansion RE of the second end A2 of the first element A and a fixing ring RG inserted in the tubular portion of the second end B2 of the second element B . Alternatively, the raising spring could be interposed between the second element B and the fixing element 18 , arranged to lock the castellation assembly within the capsule bore 17 .

[0073] The castellation assembly is preferably fixed in the capsule bore 17 by means of a snap ring 18 or threaded ring . Other locking device such as a set screw, pressed bushing, among others , can be implemented to achieve the same result , known to skilled person .

[0074] The first end Bl of the second element B, as the shaft 20 of the prior art , can comprise a press foot 21 configured to press the exhaust valve stem or a valve bridge or another rocker arm, or other valvetrain component , to reali ze the compressed air release of the engine brake operation .

[0075] Many changes , modi fications , variations and other uses and applications of the subj ect invention will become apparent to those skilled in the art after considering the speci fication and the accompanying drawings which disclose preferred embodiments thereof as described in the appended claims .

[0076] The features disclosed in the prior art background are introduced only in order to better understand the invention and not as a declaration about the existence of known prior art . In addition, said features define the context of the present invention, thus such features shall be considered in common with the detailed description .

[0077] Further implementation details will not be described, as the man skilled in the art is able to carry out the invention starting from the teaching of the above description .

Claims

CLAIMS1 . An engine brake rocker arm assembly (RA) including a rocker arm (RA) arranged to rock in response to a cam supported by a cam shaft in order to press down at least an exhaust valve (EV) , a castellation assembly (1 ) and a first hydraulic actuator (70) arranged to rotate at least an element (JK) of the castellation assembly ( 1) , wherein the castellation assembly ( 1 ) includes- a first element (A) comprising a first end (Al ) protruding outside the rocker arm, at the upper portion (URA) of the rocker arm,- a second element (B) , distinct and separated by the first element (A) , including a first end (Bl ) protruding outside the rocker arm, in an opposite direction with respect to the first end (Al ) of the first element (A) , and a second end (B2 ) defining a seat (BS ) for a second end (A2 ) of the first element (A) ,- a j acket element ( JK) , having tubular shape , arranged to envelope said second end of both said first and second elements (A, B ) , wherein the second element is provided with radial teeth (RT ) and the j acket element is provided of axial teeth (AT ) arranged to assume a first configuration named as "tooth- to-tooth configuration" and a second configuration named as " tooth-to-valley configuration" , wherein in the firstconfiguration, expanded, the castellation assembly is capable to press said exhaust valve and in the second configuration, collapsed, the castellation assembly is not capable to press said exhaust valve , wherein the second element and the j acket element are arranged in order to define a second hydraulic actuator, the assembly further including+ a raising spring (RS ) arranged to maintain said second element (B ) biased against said first element (A) and+ an oil channel ( OC ) arranged within the rocker arm to fill both the first actuator ( 70 ) and said second hydraulic actuator .

2. Assembly according to according to claim 1, wherein said first hydraulic element is arranged to rotate said j acket element, wherein the jacket element define with said first hydraulic element a pinion / rack arrangement .

3. Assembly according to claim 1 or 2 , wherein the castellation assembly ( 1) is arranged in bore ( 17) of the rocker arm and locked in said bore by means of a fixing element ( 18) such as a snap ring or a threaded ring .4 . Assembly according to anyone the previous claims , wherein the raising spring is arranged in the seat (BS) or interposed between the second element B and the fixing element 18 .

5. Assembly according to claim 4, wherein when the raising spring is arranged in the seat (BS) , it is interposed between a radial expansion (RE ) of the second end (A2 ) of the first element (A) and a fixing ring (RG) inserted in a tubular portion of the second end (B2 ) of the second element (B ) defining said seat (BS ) .6 . Combustion engine comprising an engine brake system including the assembly of anyone o f the previous claims 1 -5 . 7 . Truck including a combustion engine according to claim6 .

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