ENGINE

Cross-Reference to Related Application:

[0001] This application claims the benefit of the filing date of U.S. Provisional App. Ser.

No. 63/224,712 filed on July 22, 2021, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] This invention relates to internal combustion engines and, more particularly, to a trip mechanism and braking system for an internal combustion engine.

BACKGROUND

[0003] Engine braking is known in the art and is used for many applications, including braking heavy vehicles. For example, a compression type engine braking converts an internal combustion engine cylinder to a compressor and opens an exhaust valve of the cylinder near the end of the compression stroke. This allows the power generated in the piston to escape to the atmosphere, rather than continuing to power the vehicle.

[0004] Engine braking in certain engine platforms has heretofore been met with difficulties due to, among other issues, cost concerns and a lack of space in the engine footprint to accommodate the braking system. Therefore, further improvements in this technological area are desired.

SUMMARY

[0005] Systems, apparatus, and methods are disclosed herein relating to an engine braking system that employs a trip mechanism to provide a release of fluid pressure that holds the exhaust valve open during a compression braking event. In an embodiment, the trip mechanism includes a trip member mountable to a valve opening mechanism of the internal combustion engine. The trip mechanism is configured to open an exhaust valve during an engine braking mode of operation. The trip mechanism also includes a control valve that fluidly isolates a working fluid in a cavity during the engine braking mode of operation of the valve opening mechanism. The trip mechanism also includes a release member movable against the trip member in response to motion of the valve opening mechanism to rotate the release member and actuate the control valve to release the working fluid to cancel the engine braking mode of operation.

[0006] In an embodiment, a braking system for an internal combustion engine is provided. The braking system includes a cylinder housing a piston operably connected to a crankshaft. The cylinder further includes at least one intake valve and at least one exhaust valve. The braking system also includes a camshaft including a braking lobe rotatable with rotation of the camshaft. The braking lobe includes a brake profile and a brake cancel profile. The braking system also includes an exhaust valve opening mechanism linking the braking lobe to the at least one exhaust valve. The exhaust valve opening mechanism includes a braking piston connected to the at least one exhaust valve, a rocker lever rotatably mounted to a rocker shaft and connected to the braking piston, and a roller mounted to the rocker lever. The rocker lever includes a cavity and a fluid control valve for isolating fluid in the cavity in a braking mode of operation so the braking piston is configured to open the at least one exhaust valve in response to the brake profile of the braking lobe being in contact with the roller. The braking system also includes a trip mechanism including a trip member and a release member that moves with movement of the rocker lever. The release member is tripped by the trip member to open the fluid control valve to terminate the braking mode of operation in response to the brake cancel profile of the braking lobe acting on the roller.

[0007] This summary is provided to introduce a selection of concepts that are further described below in the illustrative embodiments. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic diagram of an internal combustion engine.

[0009] FIG. 2 is a perspective view of a portion of the internal combustion engine of

FIG. 1 including an engine braking system with a trip mechanism for cancelling an engine braking event.

[00010] FIG. 3 is an elevation view of the engine braking system and trip mechanism of FIG. 2.

[00011] FIG. 4 is a sectional view of the engine braking system and trip mechanism of FIG. 2.

[00012] FIG. 5 is a schematic view showing the tripping mechanism tripped to cancel the engine braking.

DETAILED DESCRIPTION

[00013] For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the invention as illustrated therein as would normally occur to one skilled in the art to which the invention relates are contemplated herein.

[00014] Referring to FIGs. 1-5, an embodiment of the present disclosure includes a trip mechanism 150 for a braking system 100 of an internal combustion engine 12 having a valve opening mechanism 70. The trip mechanism 150 includes a trip member 160 mountable to the valve opening mechanism 70. The valve opening mechanism 70 is configured to open an exhaust valve 72 during an engine braking mode of operation. The trip mechanism 150 also includes a control valve 120 that fluidly isolates a working fluid in a cavity 110 of valve opening mechanism 70 during the engine braking mode of operation of the valve opening mechanism 70. The trip mechanism 150 also includes a release member 152 movable against the trip member 160 in response to motion of the valve opening mechanism 70 to rotate the release member 152 and actuate the control valve 120 to release the working fluid to cancel the engine braking mode of operation.

[00015] Another embodiment of the present disclosure includes a braking system 100 for an internal combustion engine 12. The braking system 100 includes a cylinder 18 housing a piston 40 operably connected to a crankshaft 30. The cylinder 18 further includes at least one intake valve 42 and at least one exhaust valve 72. Braking system 100 also includes a camshaft 50 including a braking lobe 54 rotatable with rotation of the camshaft 50. The braking lobe 54 includes a brake profile 56 and a brake cancel profile 58. Braking system 100 also includes an exhaust valve opening mechanism 70 linking the braking lobe 54 to the at least one exhaust valve 72. The exhaust valve opening mechanism 70 includes a braking piston 106 connected to the at least one exhaust valve 72, a rocker lever 102 rotatably mounted to a rocker shaft 46 and connected to the braking piston 106, and a roller 104 mounted to the rocker lever 102 in contact with the braking lobe 54. The rocker lever 102 includes a cavity 110 and a fluid control valve 120 for isolating fluid in the cavity 110 in a braking mode of operation so the braking piston 106 is configured to open the at least one exhaust valve 72 in response to the brake profile 56 of the braking lobe 54. The braking system 100 also includes a trip mechanism 150 including a trip member 160 and a release member 152 that moves with movement of the rocker lever 102. The release member 152 is tripped by the trip member 160 to open the fluid control valve 120 to terminate the braking mode of operation in response to the brake cancel profile 58 of the braking lobe 54 acting on the roller 104.

[00016] FIG. 1 shows an internal combustion engine system 10 according to one embodiment of the present application. System 10 includes an internal combustion engine 12 having an intake system 14 and an exhaust system 16. Engine 12 can be any type of engine, and in one specific embodiment is a combustion engine that combusts any suitable fuel and includes a number of cylinders 18 each housing a piston. Cylinders 18 receive an intake flow 24 and combust a fuel provided thereto to produce an exhaust flow 26 from each of the cylinders.

[00017] In the illustrated embodiment, engine 12 includes six cylinders connected with an intake manifold 20 and an exhaust manifold 22. Engine 12 can be an in-line type engine with a single cylinder bank, although other embodiments include V-shaped cylinder arrangements, a W- type engine, or any engine arrangement with one or more cylinders. It is contemplated that engine 12 is provided as part of a powertrain for a vehicle (not shown), although other applications are also contemplated and not precluded, such as for gensets and marine applications.

[00018] Referring to FIG. 2, there is illustrated one embodiment of a portion of engine 12 along three of the cylinders 18. The illustrated portion includes a crankshaft 30, a piston 40, a camshaft 50 (FIG. 3), and a valve opening mechanism 70 that includes an engine braking system 100 and a trip mechanism 150. Piston 40 is housed in a respective one of the cylinders 18, and is rotatably connected to crankshaft 30 with a connecting rod 32 so that reciprocating movement of piston 40 rotates crankshaft 30, as is known in the art. Crankshaft 30 may be connected to camshaft 50 via gears (not shown) or other suitable arrangement such as chains or belts so that rotation of crankshaft 30 rotates camshaft 50 at, for example, half speed of crankshaft 30 with the connection arrangement providing a gear reduction, as known in the art.

[00019] Each cylinder 18 of engine 12 houses a piston 40 that is connected to crankshaft

30 and camshaft 50. Each cylinder 18 also includes at least one intake valve 42 that is opened and closed by valve opening mechanism 70 via cam lobes of camshaft 50. The opening of the intake valve(s) 42 allow a charge flow to be admitted into the combustion chamber of the respective cylinder 18 through an intake opening (not shown).

[00020] In the illustrated embodiment, the intake valve 42 includes first and second intake valves 42 connected by an intake cross head 48. Intake cross head 48 is connected to an intake rocker 44, and intake rocker 44 is rotatable about a rocker shaft 46 in response to an intake valve opening cam lobe (not shown) of camshaft 50 pushing on the intake rocker 44. The rotation of the intake rocker 44 causes the intake valves 42 to open and close.

[00021] Each cylinder 18 further includes at least one exhaust valve 72. Opening of the at least one exhaust valve 72 with valve opening mechanism 70 allows exhaust gases created by combustion of the charge flow to escape the combustion chamber of the respective cylinder 18 through an exhaust opening (not shown).

[00022] In the illustrated embodiment, the exhaust valve 72 includes first and second exhaust valves 72 connected by an exhaust valve cross head 78. Each exhaust valve(s) 72 opens and closes in response to an exhaust valve opening lobe (not shown) on camshaft 50 acting on an exhaust rocker 74 that is rotatable about rocker shaft 46. The rotation of the exhaust rocker 74 about rocker shaft 46 causes the exhaust valves 72 to open and close. In the illustrated embodiment, the piston 106 is connected to one of the exhaust valves 72 for engine braking purposes.

[00023] Referring further to FIGs. 3-4, further details of the engine braking system 100 is shown. The engine braking system 100 is connected to at least one of the exhaust valves 72. Engine braking system 100 is operable to selectively open the connected exhaust valve(s) 72 for engine braking during an engine braking mode of operation, as discussed further below. The trip mechanism 150 to operable to cancel the engine braking event during the engine braking mode of operation.

[00024] In the illustrated embodiment, the engine braking system 100 includes a rocker lever 102 rotatable about rocker shaft 46. The rocker lever 102 includes a roller 104 in contact with cam shaft 50. In particular, the roller 104 is in contact with a braking lobe 54 of camshaft 50. The braking lobe 54 includes a non-circular profile configured to act on roller 104 to rotate the rocker 102 about the rocker shaft 46 to selectively open the exhaust valve 72 when the engine braking mode of operation is active. [00025] In an embodiment, the trip mechanism 150 includes a release member 152 pivotably mounted to valve opening mechanism 70 and a trip member 160 fixedly mounted to valve opening mechanism 70. In an embodiment, release member 152 is pivotably mounted to rocker lever 102 and trip member 160 is fixedly mounted to rocker shaft 46.

[00026] The rocker lever 102 is connected to a braking piston 106 opposite the roller 104. The braking piston 106 is connected to exhaust valve 72. The braking piston 106 is collapsible or movable into rocker lever 102 and is biased toward an extended position by a spring 114. Braking piston 106 can move reciprocally in a bore 108 of rocker lever 102 to compress spring 114 during non-engine braking operation so that the exhaust valve 72 is not opened via the braking lobe 54 due to rotation of the rocker lever 102.

[00027] The engine braking system 100 includes hydraulics that work with the mechanical components described above to actuate the exhaust valve(s) 72 to initiate the engine braking mode of operation. In an embodiment, the hydraulics include fluid passages in the rocker lever 102 and its bushing, in rocker shaft 46, and in a fluid control valve 120, and the fluid is provided from a lube pump (not shown) internal to the engine. The fluid passages in the rocker lever 102 can include feeds to braking piston 106, a brake actuator 126 , and a fluid control valve 120. The rocker lever 102 receives fluid from the rocker bushing, rocker shaft 46, and control valve 120. [00028] During an active engine braking mode of operation, working fluid, such as oil, in the piston cavity 110 is pressurized to lock the braking piston 106 in an extended position to prevent reciprocation in bore 108. The fluid pressure in cavity 110 is maintained by the fluid control valve 120. In the illustrated embodiment, the fluid control valve 120 includes a valve member 122 that is normally biased against a seat 124, and an actuator 126 that extends through seat 124 to contact valve member 122. In the illustrated embodiment, the valve member 122 is a ball check valve that contacts and seals against seat 124 via a biasing force from a spring 128 located in cavity 110. The actuator 126 is normally biased outwardly from rocker lever 102 via a spring 130 so that valve member 122 is not normally contacted by actuator 126. The outer end of actuator 126 is in contact with tripping mechanism 150.

[00029] In order to cancel the engine braking mode of operation, the fluid pressure in cavity 110 must be relieved or released so that the braking piston 106 can reciprocate in bore 108. Tripping mechanism 150 includes a release member 152 and a trip member 160. Release member 152 is pivotably mounted to and moveable with movement of rocker lever 102. Release member 152 includes a body 154 forming a lever that is pivotable about a fulcrum 156 on rocker lever 102. A contact surface 158 extends along one side of body 154 and contacts trip member 160 at an end 166 of body 154 on one side of fulcrum 156. Contact surface 158 also contacts an outer end 132 of actuator 126 at an opposite side of fulcrum 156.

[00030] Trip member 160 includes an elongated trip bar 164 that extends along and parallels the rocker shaft 46. The trip bar 164 is mounted to rocker shaft 46 with mounting brackets 162 (FIG. 2). As shown in FIG. 5, trip bar 164 causes release member 152 to pivot about fulcrum 156 as shown by arrow 152’ in response to rocker lever 102 rotating a sufficient amount about rocker shaft 46 in the direction of arrow 102’. In particular, the end 166 of release member 152 pushes against trip bar 164 so that the release member 152 pushes against end 132 of actuator 126.

[00031] As discussed above, the rotation of rocker lever 102 about rocker shaft 46 is caused by braking lobe 54 of camshaft 50 acting on roller 104. The braking lobe 54 can include a brake profile 56 that causes rocker lever 102 to rotate sufficiently to open exhaust valve 72 during the engine braking mode of operation. Braking lobe 54 includes a brake cancel profile 58 that further rotates brake rocker 102 in the direction of arrow 102’, forcing contact surface 158 of release member 152 against trip bar 164 so the trip bar 164 forces release member 152 to pivot about fulcrum 156 and against end 132 of actuator 126, as shown by arrow 152’. This displaces actuator 126 against spring 130, as shown by actuator 126’, and pushes valve member 122 against spring 128 and from seat 124, as shown by valve member 122’. The pressurized working fluid in cavity 110 can then flow back through seat 124, allowing braking piston 106 to reciprocate in bore 108 so that exhaust valve 72 is able to close and cancel the engine braking mode of operation.

[00032] In an embodiment, the trip mechanism 150 includes trip member 160 and release member 152 that is engaged the trip member 160. The release member 152 rotates with the rotation of the rocker lever 102 about the rocker shaft 46. When the rocker lever 102 rotates to a certain position due to the braking lobe 54 acting on the rocker lever 102, the resulting movement of the release member 152 causes the trip member 160 to actuate the release member 152 to manipulate the control valve 120 of the engine braking system 100 to cancel the engine braking event. [00033] In an embodiment, the release member 152 forms a lever that moves about a fulcrum 156 on rocker lever 102 with rotation of the rocker lever 102 about the rocker shaft 46 due to contact of the release member 152 with the trip member 160 In an embodiment, the release member 152 actuates a volume of a fluid control valve 120 when engaged by the trip member 160 to cancel the engine braking event.

[00034] Many aspects of the present invention are envisioned. For example, one aspect is directed to the system and apparatus of the claims appended hereto. According to one aspect, a trip mechanism for a braking system of an internal combustion engine including a valve opening mechanism is provided. The trip mechanism includes a trip member mountable to the valve opening mechanism. The valve opening mechanism is configured to open an exhaust valve during an engine braking mode of operation. The trip mechanism includes a control valve that fluidly isolates a working fluid in a cavity in the valve opening mechanism during the engine braking mode of operation of the valve opening mechanism. The trip mechanism also includes a release member movable against the trip member in response to motion of the valve opening mechanism. The trip member rotates the release member to actuate the control valve and release the working fluid to cancel the engine braking mode of operation.

[00035] In an embodiment, the release member is a lever that includes a contact surface, the control valve includes an actuator, and the contact surface contacts the trip member and the actuator of the control valve. In an embodiment, the trip member is an elongated bar.

[00036] In an embodiment, the release member is pivotably mounted to the valve opening mechanism. In a further embodiment, the trip member is fixedly mounted to the valve opening mechanism.

[00037] In an embodiment, the control valve includes an actuator and a valve member that is biased against a seat of the control valve, and the control valve is actuated by the release member displacing the actuator against the valve member to push the valve member off of the seat. In a further embodiment, the valve member is a ball that is spring biased against the seat and the actuator is spring biased away from the ball.

[00038] According to another aspect of the disclosure, a braking system for an internal combustion engine is provided. The braking system includes a cylinder housing a piston operably connected to a crankshaft. The cylinder further includes at least one intake valve and at least one exhaust valve. The braking system includes a camshaft including a braking lobe rotatable with rotation of the camshaft. The braking lobe includes a brake profile and a brake cancel profile. The braking system also includes an exhaust valve opening mechanism linking the braking lobe to the at least one exhaust valve. The exhaust valve opening mechanism includes a braking piston connected to the at least one exhaust valve and a rocker lever rotatably mounted to a rocker shaft and connected to the braking piston. The rocker lever includes a cavity and a fluid control valve for isolating fluid in the cavity in a braking mode of operation. The exhaust valve opening mechanism also includes a roller mounted to the rocker lever. The braking piston is configured to open the at least one exhaust valve in response to the brake profile of the braking lobe acting on the roller. The braking system also includes a trip mechanism including a trip member and a release member that moves with movement of the rocker lever. The release member is tripped by the trip member to open the fluid control valve to terminate the braking mode of operation in response to the brake cancel profile of the braking lobe being in contact with the roller.

[00039] In an embodiment, the braking piston of the exhaust valve opening mechanism is locked in an extended position by pressurization of the working fluid to prevent movement of the braking piston during the engine braking mode of operation. The braking piston is movable when the working fluid pressure is released.

[00040] In an embodiment, the fluid control valve includes a seat, a valve member biased against the seat to isolate the fluid in the cavity, and an actuator that extends between the release member and the valve member. In a further embodiment, the release member is in contact with the actuator and displaces the actuator against the valve member to displace the valve member when the release member is tripped by the trip member.

[00041] In an embodiment, the trip member rotates the release member opposite to a direction of rotation of the rocker lever about the rocker shaft. In a further embodiment, the trip member is mounted to the rocker shaft.

[00042] In an embodiment, the release member includes a lever pivotably mounted to the rocker lever at a fulcrum. In a further embodiment, the lever includes a contact surface that extends between and is in contact with the trip member and the fluid control valve.

[00043] In an embodiment, the braking piston is mounted in a bore of the rocker lever in fluid communication with the cavity. [00044] In an embodiment, the braking system includes a plurality of cylinders and a plurality of exhaust valve opening mechanisms associated with respective ones of the plurality of cylinders. In a further embodiment, the trip mechanism includes a plurality of release arms associated with respective ones of the plurality of cylinders, and the trip member extends along between the plurality of cylinders in contact with the plurality of release arms.

[00045] In an embodiment, the roller is in contact with the braking lobe of the camshaft. In an embodiment, the at least one exhaust valve includes a first exhaust valve and a second exhaust valve. A cross head connects the first and second exhaust valves, and the braking piston is connected to the first exhaust valve.

[00046] While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain exemplary embodiments have been shown and described. Those skilled in the art will appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.