TYPE III CAM SIDE CYLINDER DEACTIVATION

Abstract

A rocker arm assembly includes a rocker arm configured to rotate about a rocker shaft and having a valve side end configured to selectively engage an engine valve, and a cam side end configured to be selectively engaged by a camshaft. A cylinder deactivation (CDA) capsule is coupled to the cam side end and includes an outer body having at least one slot formed therein, the outer body configured to be coupled to the rocker arm, and an inner plunger at least partially received within the outer body and having at least one outwardly extending tab. The inner plunger is configured to translate within the outer body, and the at least one outwardly extending tab is received within the at least one slot and a groove formed in the rocker arm to facilitate preventing rotation of the inner plunger and outer body relative to the rocker arm.

Description

FIELD

The present disclosure relates generally to a rocker arm assembly for use in a valve train assembly and, more particularly, to a rocker arm assembly having a cylinder deactivation mechanism.

BACKGROUND

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. A compression engine braking system is arranged, when activated, 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. This causes the engine to function as a power consuming air compressor which slows the vehicle.

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 itself presses down on the exhaust valve to open it. A hydraulic lash adjuster may also be provided in the valve train assembly to remove any lash or gap that develops between the components in the valve train assembly.

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

SUMMARY

In one example aspect, a cylinder deactivation (CDA) capsule for a valvetrain assembly having at least one rocker arm is provided. The CDA capsule includes an outer body having at least one slot formed therein, the outer body configured to be coupled to the rocker arm, and an inner plunger at least partially received within the outer body and having at least one outwardly extending tab. The inner plunger is configured to translate within the outer body, and the at least one outwardly extending tab is received within the at least one slot to facilitate preventing rotation of the inner plunger relative to the outer body. The CDA capsule is movable between an activated position where the CDA capsule is configured to transfer motion from a camshaft, and a deactivated position where the CDA capsule is configured to absorb the motion from the camshaft.

In addition to the foregoing, the described CDA capsule may include one or more of the following features: a latching mechanism operably associated between the outer body and the inner plunger, the latching mechanism selectively movable between a latched position that facilitates preventing relative movement between the plunger and the outer body, and an unlatched position that facilitates movement between the plunger and the outer body; wherein the latching mechanism includes a pair of opposed pins and a biasing mechanism disposed therebetween; and wherein each opposed pin includes a pin shoulder configured to abut against a shoulder of the outer body when the latching mechanism is in the latched position.

In addition to the foregoing, the described CDA capsule may include one or more of the following features: wherein the outer body includes a fluid port configured to provide a supply of fluid to the opposed pins to move the latching mechanism from the latched position to the unlatched position; wherein the outer body includes a fluid communication groove formed therein, the fluid communication groove in fluid communication with the fluid port; a biasing mechanism disposed between the plunger and the outer body, the biasing mechanism configured to absorb motion of the plunger within the outer body when the latching mechanism is in the unlatched position, to thereby provide a lost motion feature; wherein the biasing mechanism comprises a first spring and a second spring; and wherein the at least one slot comprises a pair of diametrically opposed slots, wherein the at least one outwardly extending tab comprises a pair of diametrically opposed outwardly extending tabs, and wherein the outwardly extending tabs are received within the slots to prevent relative rotation between the inner plunger and the outer body.

In another example aspect, a rocker arm assembly for a valvetrain assembly is provided. The rocker arm assembly includes a rocker arm configured to rotate about a rocker shaft and having a valve side end configured to selectively engage an engine valve, and a cam side end configured to be selectively engaged by a camshaft. A cylinder deactivation (CDA) capsule is coupled to the cam side end and is movable between an activated position where the CDA capsule transfers motion from the camshaft to the engine valve, and a deactivated position where the CDA capsule absorbs the motion from the camshaft without transferring said motion to the engine valve.

In addition to the foregoing, the described rocker arm assembly may include one or more of the following features: wherein the rocker arm valve side end includes a mechanical lash adjuster assembly; and wherein the CDA capsule includes an outer body having at least one slot formed therein, and an inner plunger at least partially received within the outer body and having at least one outwardly extending tab, the inner plunger configured to translate within the outer body, wherein the at least one outwardly extending tab is received within the at least one slot to facilitate preventing rotation of the inner plunger relative to the outer body.

In addition to the foregoing, the described rocker arm assembly may include one or more of the following features: wherein the CDA capsule is at least partially disposed within a bore formed in the rocker arm cam side end; wherein a groove is formed in an inner wall of the rocker arm that defines the bore, and wherein the at least one outwardly extending tab is received within the groove to further facilitate preventing rotation of the inner plunger and the outer body within the bore relative to the rocker arm; and wherein the at least one slot comprises a pair of diametrically opposed slots, wherein the at least one outwardly extending tab comprises a pair of diametrically opposed outwardly extending tabs, and wherein the outwardly extending tabs are received within the slots to facilitate preventing relative rotation between the inner plunger and the outer body.

In addition to the foregoing, the described rocker arm assembly may include one or more of the following features: a latching mechanism operably associated between the outer body and the inner plunger, the latching mechanism selectively movable between a latched position that facilitates preventing relative movement between the plunger and the outer body, and an unlatched position that facilitates movement between the plunger and the outer body; and wherein the latching mechanism includes a pair of opposed pins and a biasing mechanism disposed therebetween, and wherein each opposed pin includes a pin shoulder configured to abut against a shoulder of the outer body when the latching mechanism is in the latched position.

In addition to the foregoing, the described rocker arm assembly may include one or more of the following features: wherein the outer body includes a fluid port configured to provide a supply of fluid to the opposed pins to move the latching mechanism from the latched position to the unlatched position, and wherein the outer body includes a fluid communication groove formed therein, the fluid communication groove in fluid communication with the fluid port; and a biasing mechanism disposed between the plunger and the outer body, the biasing mechanism configured to absorb motion of the plunger within the outer body when the latching mechanism is in the unlatched position, to thereby provide a lost motion feature.

In another example aspect, a rocker arm assembly for a valvetrain assembly is provided. The rocker arm assembly includes a rocker arm configured to rotate about a rocker shaft and having a valve side end configured to selectively engage an engine valve, and a cam side end configured to be selectively engaged by a camshaft. A cylinder deactivation (CDA) capsule is coupled to the cam side end and includes an outer body having at least one slot formed therein, the outer body configured to be coupled to the rocker arm, and an inner plunger at least partially received within the outer body and having at least one outwardly extending tab. The inner plunger is configured to translate within the outer body, and the at least one outwardly extending tab is received within the at least one slot and a groove formed in the rocker arm to facilitate preventing rotation of the inner plunger and outer body relative to the rocker arm. The CDA capsule is movable between an activated position where the CDA capsule is configured to transfer motion from the camshaft to the engine valve, and a deactivated position where the CDA capsule is configured to absorb the motion from the camshaft.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a deactivating exhaust rocker arm constructed in accordance to one example of the present disclosure;

FIG. 2 is a perspective view of an example deactivating capsule of the exhaust rocker arm shown in FIG. 1;

FIG. 3 is a perspective view of an example outer body of the deactivating capsule shown in FIG. 2;

FIG. 4 is a perspective view of an example inner plunger of the deactivating capsule shown in FIG. 2;

FIG. 5 is a cross-sectional view of the deactivating exhaust rocker arm shown in FIG. 1 and taken along line 5-5;

FIG. 6 is a cross-sectional view of the deactivating capsule shown in FIG. 2, taken along line 6-6 and shown in an example latched position;

FIG. 7 is a cross-sectional view of the deactivating capsule shown in FIG. 6, in an example unlatched position; and

FIG. 8 is a cross-sectional view of the deactivating capsule shown in FIG. 6, in the unlatched position and exhibiting lost motion.

DETAILED DESCRIPTION

Heavy duty (HD) diesel engines require high braking power, in particular at low engine speed. Some HD diesel engines are configured with valvetrains having a valve bridge and include with single overhead cam (SOHC) and overhead valve (OHV) valvetrain. The present disclosure incorporates mechanisms that allow for selective activation and deactivation of a rocker arm. In the deactivated state, the rocker arm may exhibit lost motion. In the activated state, the rocker arm may open one exhaust valve to perform a braking event. Additionally, anti-rotation features can be provided for the mechanisms to prevent rotation relative to the rocker arm.

With initial reference to FIG. 1, an engine brake rocker arm assembly fora Type III valvetrain assembly is shown and generally identified at reference 10. It will be appreciated that while shown in a Type III arrangement, it is within the scope of the present disclosure for the various features described herein to be used in other arrangements. In the example embodiment, the engine brake rocker arm assembly 10 includes an exhaust valve rocker arm assembly 12 configured to be incorporated in a valvetrain assembly that utilizes engine braking such as one having a pair of three-cylinder bank portions in a six-cylinder engine. It will be appreciated however that the present teachings are not so limited. In this regard, the present disclosure may be used in any valvetrain assembly.

The valvetrain assembly is supported in a valvetrain carrier (not specifically shown) and can include two rocker arms per cylinder. In one example embodiment, each cylinder includes an exhaust valve rocker arm assembly 12 and an intake valve rocker arm assembly (not shown). The exhaust valve rocker arm assembly 12 is configured to control motion of exhaust valves of an associated engine, for example during operation in an engine braking mode. The intake valve rocker arm assembly is configured to control opening of intake valves of the engine. In the example implementation, exhaust valve rocker arm assembly 12 utilizes a cam-side cylinder deactivating (CDA) capsule configured to be selectively deactivated to prevent actuation of an exhaust valve.

In the example embodiment, the exhaust valve rocker arm assembly 12 can include an exhaust rocker arm 14 that rotates about a rocker shaft 16, a valve bridge 18, and a CDA capsule 20. In the example embodiment, the valve bridge 18 is configured to engage first and second exhaust valves 24, 26 associated with a cylinder of the engine and may be selectively actuated via an additional rocker arm (not shown). In the illustrated example, the first exhaust valve 24 is biased by a valve spring 28, and the second exhaust valve 26 is biased by a valve spring 30. The exhaust rocker arm 14 rotates around the rocker shaft 16 based on a lift profile or cam lobe 32 of a cam shaft 34, as described herein in more detail, and a pass through pin 36 is positioned on the valve bridge 18 to enable actuation of exhaust valve 26 without actuation of valve bridge 18 or first exhaust valve 24.

As shown, the cam lobe 32 is configured to drive a first end 38 of the exhaust rocker arm 14, which pivots the rocker arm 14 about the fixed cam shaft 34, thereby causing a second end 42 of the exhaust rocker arm 14 to press the pass through pin 36, for example to perform an engine braking operation. Although shown as positioned to contact pass through pin 36, it will be appreciated that rocker arm 14 may be a standalone rocker arm and/or act on the center of the bridge 18 to provide a standard valve lift of exhaust valves 24 and/or 26.

In the illustrated example, the rocker arm second end 42 includes a mechanical lash adjuster assembly 44 that generally includes a lash adjustment screw 46, a nut 48, and an e-foot 50. The lash adjustment screw 46 includes a first end 52 and an opposite second end 54 and extends through a bore 56 formed in the rocker arm second end 42. The nut 48 is threadably coupled to the first end 52, and the e-foot 50 is coupled to the second end 54. The valve lash set at a contact point of the bridge 18 (e.g., pin 36) may be adjusted by rotating the nut 48.

With additional reference to FIGS. 2-5, the CDA capsule 20 will be described in more detail. In some embodiments, CDA capsule 20 is utilized in a diesel engine in order to increase exhaust temperature for exhaust thermal management when the exhaust is below a predetermined temperature, and improve engine fuel efficiency during low load operation. In the example implementation, CDA capsule 20 is disposed at least partially within a bore 60 (FIG. 5) formed within the rocker arm cam-side first end 38 and can generally include an outer body 70, an inner plunger 72, a latch or latching mechanism 74, and a contacting element or roller 76.

With particular reference to FIGS. 2 and 3, in the example embodiment, the outer body 70 is generally cylindrical and includes a first end 78 and an opposite second end 80. The outer body 70 also includes an oil communication groove 82 in fluid communication with a plurality of oil ports 84 via a plurality of oil channels 86. A pair of diametrically opposed slots 88 are formed in the outer body 70 and configured to receive portions of the inner plunger 72 to prevent rotation of the inner plunger 72 within the outer body 70, as described herein in more detail. In one example, the outer body 70 is threaded onto the rocker arm 14 up to a predetermined length such that slots 88 are aligned or substantially aligned with grooves 62 formed within an inner wall 64 of the rocker arm 14 that defines the bore 60 and relative to rocker arm 14.

With additional reference to FIG. 4, in the example embodiment, the inner plunger 72 is generally cylindrical and includes a main body 90 having a pair of diametrically opposed tabs 92, a plurality of oil passages 94, and a pair of flanges or arms 96. As shown in FIG. 2, the inner plunger 72 is disposed at least partially within outer body 70 such that the tabs 92, which extend outwardly from the main body 90, are received within the outer body opposed slots 88. Moreover, as shown in FIG. 5, the tabs 92 are received within the grooves 62. In this way, the inner plunger 72 is configured to prevent rotation of both the outer body 70 and the inner plunger 72 within the bore 60.

In the example embodiment, inner plunger 72 is configured to selectively slide within the outer body 70 when CDA capsule 20 is in an unlatched position, as described herein in more detail. The oil passages 94 are configured to selectively align with oil ports 84 to enable fluid communication therebetween, and the arms 96 each include an aperture 98 to receive an axle 100 (FIG. 2) for rotatably supporting roller 76 between the opposed arms 96.

As shown in FIG. 5, in the example embodiment, inner plunger 72 defines a cavity 110 to receive one or more biasing mechanisms 112 (e.g., a spring) such that biasing mechanism 112 is seated between the plunger main body 90 and a cap 114. A nut 116 is secured to the outer body first end 78 and is configured as a stopping feature to limit upward movement of inner plunger 72 a predetermined distance. Accordingly, in the example arrangement, the biasing mechanism 112 is configured to bias the inner plunger 72 outward from the outer body 70 and absorb upward motion of cam lobe 32 when CDA capsule 20 is in the unlatched position, thereby providing a lost motion feature. Thus, when in an activated or latched position (FIG. 6), the CDA capsule 20 acts as a unitary body and transfers motion from the cam lobe 32 to the first end 38 of the exhaust rocker arm 14 via roller 76. In contrast, when the CDA capsule 20 is in the deactivated or unlatched position (FIG. 7), upward movement of cam lobe 32 causes the inner plunger 72 to slide upward within outer body 70, as shown in FIG. 8. The biasing mechanism 112 subsequently absorbs the upward motion of cam lobe 32 without transferring said motion to the rocker arm 14.

With additional reference to FIGS. 6-8, in the example implementation, the latching mechanism 74 is configured to selectively move between the latched position (FIG. 6) and the unlatched position (FIG. 7). In the latched position, inner plunger 72 is prevented from movement relative to the outer body 70. In the unlatched position, inner plunger 72 is movable within and relative to the outer body 70.

As shown in FIG. 6, latching mechanism 74 is disposed within a latch cavity 118 of the inner plunger 72 and generally includes a pair of opposed pins 120 having a biasing mechanism (e.g., a spring) 122 arranged therebetween. The biasing mechanism 122 is configured to bias pins 120 away from each other and outward toward outer body 70. As such, when oil is not supplied to oil ports 84, biasing mechanism 122 biases pins 120 outward such that a shoulder 124 of each pin 120 is disposed adjacent a shoulder 126 of outer body 70. In this way, upward movement of inner plunger 72 is prevented by pin shoulder 124 abutting against outer body shoulder 126, and the upward movement is transferred to outer body 70 and thus rocker arm 14.

However, when a signal is received to transition CDA capsule 20 to the unlatched position, an oil control valve (OCV, not shown) provides a supply of oil to oil ports 84. The force of the supplied oil against pins 120 overcomes the biasing force of biasing mechanism 122, and the pins 120 move toward each other, as shown in FIG. 7. As such, pin shoulders 124 are moved out of engagement with outer body shoulders 126, thereby enabling upward movement of plunger 72 within outer body 70 where biasing mechanism 112 subsequently absorbs the upward motion of cam lobe 32 and prevents transfer of the motion to the rocker arm 14, as shown in FIG. 8. Additionally, a lubrication passage 128 is formed in the inner plunger 72 and is fluidly coupled to the latch cavity 118 to selectively provide lubrication to the roller 76 and axle 100. Although a particular latching mechanism 74 configuration is shown in FIGS. 6-8, it will be appreciated that the latching mechanism 74 can have various configurations that enable rocker arm assembly 10 to function as described herein. For example, in one alternative configuration, latching mechanism 74 can include an electromagnetic actuator (not shown) configured to receive a controller signal to selectively retract and deploy a latching device (e.g., pins 120) to enable and disable the CDA function, thereby obviating a hydraulic system and OCV.

Described herein are systems and methods for providing selective activation and deactivation of an engine braking rocker arm. The systems include a CDA capsule disposed on a cam-side of the rocker arm. Additionally, the CDA capsule can include anti-rotation features to prevent rotation of one or more CDA capsule components within and relative to the rocker arm. Because for some diesel engines, the injectors are placed very close to the rocker arms, it can be difficult to use a capsule for deactivation on the valve side. Accordingly, the present assembly provides a deactivation capsule installation on the cam side to achieve deactivation for such diesel engines.

The foregoing description of the examples has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. A cylinder deactivation (CDA) capsule for a valvetrain assembly having at least one rocker arm, the CDA capsule comprising: an outer body having at least one slot formed therein, the outer body configured to be coupled to the rocker arm; andan inner plunger at least partially received within the outer body and having at least one outwardly extending tab, the inner plunger configured to translate within the outer body,wherein the at least one outwardly extending tab is received within the at least one slot to facilitate preventing rotation of the inner plunger relative to the outer body, andwherein the CDA capsule is movable between an activated position where the CDA capsule is configured to transfer motion from a camshaft, and a deactivated position where the CDA capsule is configured to absorb the motion from the camshaft.

2. The CDA capsule of claim 1, further comprising a latching mechanism operably associated between the outer body and the inner plunger, the latching mechanism selectively movable between a latched position that facilitates preventing relative movement between the plunger and the outer body, and an unlatched position that facilitates movement between the plunger and the outer body.

3. The CDA capsule of claim 2, wherein the latching mechanism includes a pair of opposed pins and a biasing mechanism disposed therebetween.

4. The CDA capsule of claim 3, wherein each opposed pin includes a pin shoulder configured to abut against a shoulder of the outer body when the latching mechanism is in the latched position.

5. The CDA capsule of claim 3, wherein the outer body includes a fluid port configured to provide a supply of fluid to the opposed pins to move the latching mechanism from the latched position to the unlatched position.

6. The CDA capsule of claim 5, wherein the outer body includes a fluid communication groove formed therein, the fluid communication groove in fluid communication with the fluid port.

7. The CDA capsule of claim 1, further comprising a biasing mechanism disposed between the plunger and the outer body, the biasing mechanism configured to absorb motion of the plunger within the outer body when the latching mechanism is in the unlatched position, to thereby provide a lost motion feature.

8. The CDA capsule of claim 7, wherein the biasing mechanism comprises a first spring and a second spring.

9. The CDA capsule of claim 1, wherein the at least one slot comprises a pair of diametrically opposed slots, wherein the at least one outwardly extending tab comprises a pair of diametrically opposed outwardly extending tabs, and wherein the outwardly extending tabs are received within the slots to prevent relative rotation between the inner plunger and the outer body.

10. A rocker arm assembly for a valvetrain assembly, the rocker arm assembly comprising: a rocker arm configured to rotate about a rocker shaft and having a valve side end configured to selectively engage an engine valve, and a cam side end configured to be selectively engaged by a camshaft; anda cylinder deactivation (CDA) capsule coupled to the cam side end and movable between an activated position where the CDA capsule transfers motion from the camshaft to the engine valve, and a deactivated position where the CDA capsule absorbs the motion from the camshaft without transferring said motion to the engine valve.

11. The rocker arm assembly of claim 10, wherein the rocker arm valve side end includes a mechanical lash adjuster assembly.

12. The rocker arm assembly of claim 10, wherein the CDA capsule comprises: an outer body having at least one slot formed therein; andan inner plunger at least partially received within the outer body and having at least one outwardly extending tab, the inner plunger configured to translate within the outer body,wherein the at least one outwardly extending tab is received within the at least one slot to facilitate preventing rotation of the inner plunger relative to the outer body.

13. The rocker arm assembly of claim 12, wherein the CDA capsule is at least partially disposed within a bore formed in the rocker arm cam side end.

14. The rocker arm assembly of claim 13, wherein a groove is formed in an inner wall of the rocker arm that defines the bore, and wherein the at least one outwardly extending tab is received within the groove to further facilitate preventing rotation of the inner plunger and the outer body within the bore relative to the rocker arm.

15. The rocker arm assembly of claim 12, wherein the at least one slot comprises a pair of diametrically opposed slots, wherein the at least one outwardly extending tab comprises a pair of diametrically opposed outwardly extending tabs, and wherein the outwardly extending tabs are received within the slots to facilitate preventing relative rotation between the inner plunger and the outer body.

16. The rocker arm assembly of claim 12, further comprising a latching mechanism operably associated between the outer body and the inner plunger, the latching mechanism selectively movable between a latched position that facilitates preventing relative movement between the plunger and the outer body, and an unlatched position that facilitates movement between the plunger and the outer body.

17. The rocker arm assembly of claim 16, wherein the latching mechanism includes a pair of opposed pins and a biasing mechanism disposed therebetween, and wherein each opposed pin includes a pin shoulder configured to abut against a shoulder of the outer body when the latching mechanism is in the latched position.

18. The rocker arm assembly of claim 17, wherein the outer body includes a fluid port configured to provide a supply of fluid to the opposed pins to move the latching mechanism from the latched position to the unlatched position, and wherein the outer body includes a fluid communication groove formed therein, the fluid communication groove in fluid communication with the fluid port.

19. The rocker arm assembly of claim 12, further comprising a biasing mechanism disposed between the plunger and the outer body, the biasing mechanism configured to absorb motion of the plunger within the outer body when the latching mechanism is in the unlatched position, to thereby provide a lost motion feature.

20. A rocker arm assembly for a valvetrain assembly, the rocker arm assembly comprising: a rocker arm configured to rotate about a rocker shaft and having a valve side end configured to selectively engage an engine valve, and a cam side end configured to be selectively engaged by a camshaft; anda cylinder deactivation (CDA) capsule coupled to the cam side end and comprising:an outer body having at least one slot formed therein, the outer body configured to be coupled to the rocker arm; and an inner plunger at least partially received within the outer body and having at least one outwardly extending tab, the inner plunger configured to translate within the outer body,wherein the at least one outwardly extending tab is received within the at least one slot and a groove formed in the rocker arm to facilitate preventing rotation of the inner plunger and outer body relative to the rocker arm, andwherein the CDA capsule is movable between an activated position where the CDA capsule is configured to transfer motion from the camshaft to the engine valve, and a deactivated position where the CDA capsule is configured to absorb the motion from the camshaft.