GB2593916A

GB2593916A - Engine brake device for an engine of a vehicle

Info

Publication number: GB2593916A
Application number: GB2005261.9A
Authority: GB
Inventors: Miller Adam
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2020-04-09
Filing date: 2020-04-09
Publication date: 2021-10-13
Also published as: GB202005261D0

Abstract

An i.c. engine compression release brake device comprises a firing rocker arm 12 for actuating a pair of exhaust valves in engine firing mode, and a brake rocker arm 14 for actuating the exhaust valves in engine braking mode. A sliding device 28 is movable, via a transition position T, between a firing position (F, fig.1) in which an actuating element 30, eg a hydraulic lash adjuster (HLA), is located between the firing rocker arm 12 and a first load surface 18 of a valve bridge 16, and a brake position (B, fig.3) in which the actuating element 30 is located between the brake rocker arm 14 and a second, adjacent, load surface 20 of the valve bridge 16. The sliding device 28 may be moved by a hydraulic, electronic, electromagnetic or pneumatic actuator 37 and may comprise an element 36 having spaced collars 38, 40 defining the end positions of the sliding movement. The actuating element 30 is retractable by a spring (42, fig.5) which keeps the element 30 retracted until the respective rocker arm 12, 14 is actuated.

Description

ENGINE BRAKE DEVICE FOR AN ENGINE OF A VEHICLE

FIELD OF THE INVENTION

[0001] The invention relates to an engine brake device for an engine of a vehicle. BACKGROUND INFORMATION [0002] US 9 874 123 B2 shows an engine compression brake device comprising a camshaft which has a cam group with a firing cam and a brake cam. CN 103195534A1 shows a diesel engine auxiliary braking device. Moreover, US 2011/0132298 Al shows a system for actuating an engine exhaust valve for engine braking. Furthermore, US 2012/0048232 Al shows a method of selectively actuating an engine valve to produce an engine valve event.

SUMMARY OF THE INVENTION

[0003] It is an object of the present invention to provide an engine brake device for an engine of a vehicle such that the engine brake device and thus the engine can be switched between a braking mode and a firing mode in a particular advantageous way.

[0004] This object is solved by an engine brake device of the independent claim. Advantageous embodiments with expedient developments of the invention are indicated in the other patent claims.

[0005] The engine brake device for an engine of a vehicle, according to the present invention, comprises at least one firing rocker arm configured to actuate at least one exhaust valve in a firing mode of the engine brake device and thus the engine. Preferably, the engine is configured as a combustion engine. Furthermore, the engine brake device may comprise at least one firing cam configured to actuate the firing rocker arm. The engine brake device further comprises at least one brake rocker arm configured to actuate the at least one exhaust valve in a braking mode of the engine brake device and thus the engine. Moreover, the engine brake device may comprise at least one brake cam configured to actuate the brake rocker arm. For example, the firing and brake cams are parts of a camshaft which, for example, can rotate about a rotation axis in relation to a housing of the engine. Thus, the firing and brake cams can rotate about said rotation axis in relation to housing thereby actuating, in particular swiveling, the fire and the brake rocker arms. The housing may be configured as a cylinder head.

[0006] The engine brake device further comprises at least one valve bridge via which, by actuating the valve bridge, the at least one exhaust valve is actuatable by the brake and firing rocker arms respectively. This means that the at least one exhaust valve is actuated by actuating the valve bridge. The valve bridge can be actuated by the brake rocker arm and the firing rocker arm. The valve bridge comprises a first load surface and a second load surface. The second load surface is arranged beside the first load surface along a moving direction. Moreover, the engine brake device comprises at least one sliding device which is slidable along the moving direction and in relation to the brake rocker arm, the firing rocker arm and the valve bridge between at least one firing position and at least one brake position. In the firing position, at least one actuating element of the sliding device is functionally arranged between the firing rocker arm and the first load surface such that the valve bridge is actuatable via the first load surface and the actuating element by the firing rocker arm (i.e. by actuating the firing rocker arm by the firing cam). In the brake position, the actuating element of the sliding device is functionally arranged between the brake rocker arm and the second load surface such that the valve bridge is actuatable via the second load surface and the actuating element by the brake rocker arm (i.e. by actuating the brake rocker arm by the brake cam). The feature that the firing rocker arm can be actuated by the firing cam means that by moving, in particular rotating, the firing cam the firing rocker arm is moved, in particular pivoted, by the firing cam. Consequently, the feature that the brake rocker arm can be actuated by the brake cam means that by moving, in particular rotating, the brake cam the brake rocker arm is moved, in particular swiveled or pivoted, by the brake cam. The feature that the actuating element of the sliding device is functionally arranged between the firing rocker arm and the first load surface in the firing position means that, in the firing position, the movement of the firing rocker arm is transferred via the actuating element to the valve bridge such that the valve bridge is actuated, in particular moved, via the actuating element by the firing rocker arm (i.e. by actuating the firing rocker arm). In other words, in the firing position, the actuating element is actuated, in particular moved, by the firing rocker arm when actuating the firing rocker arm. By actuating the actuating element, the valve bridge is actuated, in particular moved, such that the at least one exhaust valve is actuated, in particular moved, by the valve bridge. Consequently, the feature that, in the brake position, the actuating element is functionally arranged between the brake rocker arm and the second load surface means that the movement of the brake rocker arm is transferred via the actuating element to the valve bridge such that the valve bridge is actuated, in particular moved, via the actuating element by the brake rocker arm (i.e. by actuating the brake rocker arm). In other words, in the brake position the valve bridge is actuated, in particular moved, via the actuating element by the brake rocker arm (i.e. by actuating the brake rocker arm such that the at least one exhaust valve is actuated by the valve bridge). By sliding the sliding device between the brake position and the firing position, the engine brake device and thus the engine can be switched between the brake mode and the firing mode in a particularly easy way. Moreover, the complexity of the engine brake device can be kept particularly low.

[0007] Preferably, the engine brake device comprises at least one actuator configured to slide the sliding device from the brake position to the firing position and/or from the firing position to the brake position. For example, the actuator is electronically, hydraulically or pneumatically operable. Thus, the engine brake device can be electronically, hydraulically or pneumatically switched between the brake mode and the firing mode. Moreover, by the engine brake according to the present invention, the need to lash the rocker arms can be eliminated.

[0008] For example, the at least one exhaust valve is assigned to a cylinder of the engine. Preferably, a second exhaust valve is also assigned to the cylinder. By the engine brake device according to the present invention, only one of the exhaust valves assigned to the cylinder may be actuated in the brake mode. However, by the engine brake device according to the present invention, both exhaust valves may be switched to the brake mode and thus may be actuated in the brake mode whereas in current, usual solutions only one of the exhaust valves is actuated in the brake mode. In current solutions, one exhaust valve continues to follow positive power timing during braking (i.e. brake mode), wherein the other exhaust valve will follow brake timing. By the present invention, both exhaust valves may be switched to the brake mode (i.e. are actuated in the brake mode) such that both exhaust valves perform brake motions and are not required to also follow positive power motions during brake mode.

[0009] Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The drawings show in: [0011] Fig. 1: A schematic front view of an engine brake device according to the present invention, wherein the engine brake device is in a firing mode; [0012] Fig. 2: A further schematic front view of the engine brake device, wherein the engine brake device is in a transition mode; [0013] Fig. 3: A further schematic front view of the engine break device, wherein the engine brake device is in a brake mode; [0014] Fig. 4: A schematic top view of the engine brake device; and [0015] Fig. 5: Part of a further schematic front view of the engine brake device.

[0016] In the figures the same elements or elements having the same function are indicated by the same reference signs.

DETAILED DESCRIPTION

[0017] Fig. 1 shows in a schematic front view an engine brake device 10 for an engine of a vehicle. Preferably, the engine is an internal combustion engine configured to drive the vehicle. The engine brake device is configured as an engine compression brake device by which the engine may operate in an engine brake mode. In the engine brake mode, the engine is or acts as an engine brake by which the vehicle can be braked. Said engine brake is a compression release engine brake in which a gas that has been compressed in at least one cylinder of the engine is released from the cylinder in such a way that at least a major portion of energy contained in the compressed gas is not used to drive the engine or the vehicle. The engine brake device 10 comprises at least one firing rocker arm 12, which is also referred to as an exhaust rocker arm. The firing rocker arm 12 is configured to actuate at least one exhaust valve in a firing mode of the engine brake device 10, and thus the engine. The at least one exhaust valve is assigned to a cylinder of the engine. Preferably, a second exhaust valve is also assigned to this cylinder, wherein, preferably, both exhaust valves can be actuated by the firing rocker arm in the firing mode. The firing rocker arm 12 is actuatable by a firing cam, which is not shown in the figures. For example, the firing cam can be part of the engine break device 10. The engine brake device 10 further comprises at least one brake rocker arm 14 configured to actuate the at least one exhaust valve in a braking mode of the engine brake device 10, and thus the engine. Preferably, the brake rocker arm 14 is configured to actuate both exhaust valves assigned to the cylinder in the braking mode. The brake rocker arm 14 is actuatable by a brake cam, which is not shown in the figures. Preferably, the brake cam is a part of the engine brake device 10. For example, each of the firing cam and the brake cam has at least one cam lobe and a base circle from which the cam lobe protrudes. The rocker arms 12 and 14 can be actuated by the respective cam lobes.

[0018] The engine brake device 10 further comprises at least one valve bridge 16 via which, by actuating the valve bridge 16, the at least one exhaust valve and the second exhaust valves are actuatable by the brake and firing rocker arms 12 and 14, respectively. The valve bridge 16 comprises a first load surface 18 and a second load surface 20. The second load surface 20 is arranged beside the first load surface 18 along a moving direction, which is illustrated in Fig. 1 by an arrow 22. For example, the rocker arms 12 and 14 are pivotably arranged on a rocker arm shaft, which is not shown in the figures, such that the rocker arms 12 and 14 can pivot or swivel about a pivot axis in relation to said rocker shaft. For example, the rocker shaft is arranged on a housing 24 of the engine brake device. Furthermore, the brake cam and the firing cam can be parts of a cam shaft which is rotatably arranged on the housing 24 such that the cam shaft and thus the firing and brake cams can rotate about the rotation axis in relation to the housing 24. Moreover, the rocker arms 12 and 14 can pivot about the pivot axis in relation to the housing 24. Moreover, for example, the moving direction extends parallel to the pivot axis and the rotation axis. By actuating the valve bridge 16, at least a portion of the valve bridge 16 is translationally moved along a bridge moving direction which is illustrated by an arrow 26. For example, the bridge moving direction extends angularly, in particular perpendicularly, to the moving direction illustrated by the arrow 22.

[0019] The engine break device 10 further comprises at least one sliding device 28 which is slidable along the moving direction and in relation to the break rocker arm 14, the firing rocker arm 12 and the valve bridge 16 between at least one firing position and at least one brake position. The firing position is shown in Fig. 1 and indicated by F. The break position of the sliding device 28 is shown in Fig. 3 and indicated by B. Fig. 2 shows a transition position of the sliding device 28, wherein the transition position is arranged between the firing position F and the brake position B. Moreover, the transition position is indicated by T in Fig. 2. In the firing position F, at least one actuating element 30 of the sliding device 28 is functionally arranged between the firing rocker arm 12 and the first load surface 18 such that the valve bridge 16 is actuatable via the first load surface 18 and the actuating element 30 by the firing rocker arm 12. Thus, in the firing position F, the valve bridge 16 is actuated via the first load surface 18, the actuating element 30 and the firing rocker arm 12 by the firing cam. Thus, both exhaust valves are actuated via the valve bridge 16, the actuating element 30 and the firing rocker arm 12 by the firing cam in the firing position F (i.e. in the firing mode). This means that the firing position F causes or effects said firing mode. In the firing mode, (i.e. in the firing position F) the valve bridge 16 and the exhaust valves are not actuated by the brake rocker arm 14, although the brake rocker arm 14 may be actuated by the brake cam in the firing mode (i.e. in the firing position F).

[0020] In the brake position B, the actuating element 30 of the sliding device 28 is functionally arranged between the brake rocker arm 14 and the second load surface 20 such that the valve bridge 16 is actuatable via the second load surface 20 and the actuating element 30 by the brake rocker arm 14. This means, in the brake position B (i.e. in the brake mode) the valve bridge 16 is actuated via the second load surface 20, the actuating element 30 and the brake rocker arm 14 by the brake cam. Thus, in the brake position B, both exhaust valves are actuated via the valve bridge 16, the actuating element 30 and the brake rocker arm 14 by the brake cam. Thus, the brake position B causes or effects the brake mode. In the brake mode (i.e. in the brake position B) the valve bridge 16 and the exhaust valves are not actuated by the firing rocker arm 12, although the firing rocker arm 12 may be actuated by the firing cam in the brake mode.

[0021] For example, the sliding device 28 is slidably arranged on the housing 24 along the moving direction illustrated by the arrow 22. This means the sliding device 28 can slide between the firing position F and the brake position B in relation to the rocker arms 12 and 14, in relation to the valve bridge 16 and in relation to the housing 24.

[0022] In order to slide the sliding device 28 from the firing position F to the brake position B, (i.e. in order to switch the engine brake device 10 from the firing mode to the braking mode) the sliding device 28 may slide in a first direction in relation to the housing 24, the rocker arms 12 and 14 and the valve bridge 16. Said first direction is illustrated by an arrow 32, the first direction extending parallel to the moving direction. In order to slide the sliding device 28 from the brake position B to the firing position F, (i.e. in order to switch the engine brake device 10 from the brake mode to the firing mode) the sliding device 28 may slide in a second direction in relation to the housing 24, the rocker arms 12 and 14 and the valve bridge 16. Said second direction is illustrated by an arrow 34, wherein the second direction extends parallel to the moving direction. Moreover, the second direction is opposed to said first direction.

[0023] For example, the engine brake device 10 comprises an actuator 37. According to the embodiment shown in the figures, the actuator 37 is configured to slide the sliding device 28 in the first direction. For example, the actuator 37 is a hydraulic, electronic, electromagnetic or pneumatic actuator such that the sliding device 28 may slide hydraulically, electronically, electro-magnetically or pneumatically. Moreover, for example, the engine brake device 10 can comprise a returning device configured to slide the sliding device 28 in the second direction (i.e. from the brake position B to the firing position F). For example, the return device comprises at least one return spring and/or provides a return force by which the sliding device 28 can slide in the second direction and thus from the brake position B to the firing position F. The firing mode is also referred to as a fired mode in which the vehicle is or can be driven by the engine. As can be seen from Figs. 1 to 3, the load surfaces 18 and 20 are side-by-side on a top side S of the valve bridge 16. In the embodiment shown in the figures, the sliding device 28 comprises a base element 36 which is also referred to as a slider. The slider has two collars 38 and 40, which are spaced apart from each other along the moving direction. In the firing position F, the slider is supported on the housing 24 via the collar 40 along the second direction. In the brake position B, the slider is supported on the housing 24 via the collar 38 in the first direction. Thus, for example, starting from the firing position F, the sliding device 28 can slide in the first direction until the slider is supported on the housing 24 via the collar 38. Starting from the brake position B, the sliding device 28 can slide in the second direction until the slider is supported 24 via the collar 40. Thus, for example the collars 38 and 40 define the firing and brake positions F and B. Furthermore, the sliding device 28 comprises the actuating element 30 which is also referred to as a hydraulic lash adjuster (HLA). The HLA is slidably arranged on the base element 36 along a sliding direction illustrated by the arrow 26. The sliding direction extends angularly, in particular perpendicularly, to the moving direction. In other words, the HLA is connected to the slider in such a way that the HLA can slide along the sliding direction in relation to the slider. With respect to the Figs. 1 to 3, the HLA may be mounted such that it can slide up and down relative to the slider in order to accommodate valve actuation. When the brake mode is activated, the slider will move the HLA from the load surface 18 and the corresponding rocker arm 12 to the load surface 20 and the corresponding rocker arm 14. When the firing mode is activated, the slider will move the HLA from the load surface 20 and the corresponding rocker arm 14 to the load surface 18 and the corresponding rocker arm 12. For example, in the firing position F and in the brake position B friction between the HLA and the valve bridge 16 and friction between the HLA and the respective rocker arm 12 or 14 prevent movement of the sliding device 28 until a respective roller which is rotatably mounted on the respective rocker arm 12 and 14 is on the base circle of the respective cam.

[0024] The brake and firing rocker arms 12 and 14 are configured to actuate the actuating element 30 thereby sliding the actuating element 30 along the sliding direction in relation to the base element 36 from a retracted position R (Fig. 2) to an extended position E in order to actuate the valve bridge 16. As can be seen from Fig. 5, the engine brake device 10 comprises a return spring 42 which is supported along the sliding direction on the actuating element 30 and the slider (base element 36). Thus, in the extended position E, the return spring 42 is loaded, in particular compressed. Thus, in the extended position E, the return spring 42 provides a spring force by which the actuating element 30 is or may be moved in relation to the slider from the extended position E to the retracted position R. Preferably, said spring force holds the actuating element in the retracted position R until the respective rocker arm 12 and 14 is actuated. In other words, the actuating element 30 (HLA) is kept in the retracted position R by the return spring 42 on the slider. When the respective roller is on the respective base circle of the respective cam, the respective rocker arm 12 and 14 is not actuated. Thus, the return spring 42 moves the HLA to the retracted position R thereby opening a clearance to transition even after valve wear.

[0025] In Figs. 2 and 3, an arrow 44 illustrates an activation force provided by the actuator 37. By the activation force the sliding device 28 may slide from the firing position F to the brake position B, in particular against a returning force provided by said returning device. Thus, the activation force must be retained in order to keep the sliding device 28 in the brake position B. Once the activation force is reduced or cancelled, the returning device slides the sliding device 28 back from the brake position B to the firing position F thereby switching from the brake mode to the firing mode. The slider has at least one oil duct 46 through which oil having an oil pressure can flow. Thus, the oil duct 46 is configured to guide the oil flowing through the oil duct 46 to the HLA thereby supplying the HLA with the oil flowing through the oil duct 46. Moreover, the housing 24 comprises two oil ducts 48 and 50 through which said oil can flow. This is illustrated by an arrow 52. In the firing position F the oil duct 46 in the slider is fluidically connected to the oil duct 48 in the housing 24 such that the oil flows from the oil duct 48 into the oil duct 46. In the brake position B, the oil duct 46 is fluidically connected to the oil duct 50 such that the oil flows from the oil duct 50 into the oil duct 46. Fig. 2 shows the transition position T in which the slider is moved when moving the slider from the firing position F to the brake position B and vice versa. The housing 24 has an oil vent 54. In the transition position T, the oil duct 46 is fluidically connected with the oil vent 54 in the housing 24 such that, in the transition position T, the oil in the oil duct 46 can flow out of the oil duct 46 and into the oil vent 54. For example, this allows the return spring 42 to move the HLA from the extended position E to the retracted position R. Reference Signs engine brake device 12 firing rocker arm 14 brake rocker arm 16 valve bridge 18 first load surface second load surface 22 arrow 24 housing 26 arrow 28 sliding device actuating element 32 arrow 34 arrow 36 base element 37 actuator 38 collar collar 42 return spring 44 arrow 46 oil duct 48 oil duct oil duct 52 arrow 54 oil vent * brake position * extended position * firing position * retracted position * top side * transition position

Claims

CLAIMS1. An engine brake device (10) for an engine of a vehicle, the engine brake device (10) comprising: at least one firing rocker (12) arm configured to actuate at least one exhaust valve in a firing mode, the firing rocker arm (12) being actuatable by a firing cam; at least one brake rocker arm (14) configured to actuate the at least one exhaust valve in a braking mode, the brake rocker arm (14) being actuatable by a brake cam; at least one valve bridge (16) via which, by actuating the valve bridge (16), the at least one exhaust valve is actuatable by the brake and firing rocker arms (12, 14) respectively, the valve bridge (16) comprising a first load surface (18) and a second load surface (20) which is arranged beside the first load surface (18) along a moving direction (22); and at least one sliding device (28) slidable, along the moving direction (22) and in relation to the brake rocker arm (14), the firing rocker arm (12) and the valve bridge (16), between: o at least one firing position (F) in which at least one actuating element (30) of the sliding device (28) is functionally arranged between the firing rocker arm (12) and the first load surface (18) such that the valve bridge (16) is actuatable via the first load surface (18) and the actuating element (30) by the firing rocker arm (12); and o at least one brake position (B) in which the actuating element (30) of the sliding device (28) is functionally arranged between the brake rocker arm (14) and the second load surface (20) such that the valve bridge (16) is actuatable via the second load surface (20) and the actuating element (30) by the brake rocker arm (14).
2. The engine brake device (10) according to claim 1, wherein the sliding device (28) comprises a base element (36) and the actuating element (30) which is slidably arranged on the base element (36) along a sliding direction (26) extending angularly, in particular perpendicularly, in relation to the moving direction (22).
3. The engine brake device (10) according to claim 2, wherein the brake and firing rocker arms (12, 14) are configured to actuate the actuating element (30) thereby sliding the actuating element (30) along the sliding direction (26) in relation to the base element (36) from a retracted position (R) to an extended position (E) in order to actuate the valve bridge (16).
4. The engine brake device (10) according to claim 2 or 3, wherein the base element (36) comprises at least one oil duct (46) configured to guide oil to the actuating element (30).