Valve lifter anti-rotation device and valve lifter assembly in a valve actuation system

Abstract

An engine valve actuation system includes a rotatable camshaft, a first valve lifter, and a second valve lifter configured to actuate a valve in an engine in response to rotation of a cam of the camshaft. The engine valve actuation system includes an anti-rotation device having a collar having a sleeve portion and a boss portion, and a bridge connector configured to couple with one of the valve lifters. The other of the valve lifters is slidably received in the sleeve portion. The anti-rotation device reciprocates with the one of the valve lifters and limits rotation of each of the valve lifters during use.

Description

Technical Field

[0001] The present invention generally relates to a valve actuation system, and more specifically to an anti-rotation device for a valve tappet. Background Technology

[0002] Internal combustion engines typically employ multiple valves to control the fluid connections between different engine components, such as intake and exhaust valves, to open and close the intake and exhaust connections to the combustion cylinders. Engine valve actuation is usually achieved through a mechanical linkage between the engine crankshaft and one or more rotating camshafts, which in turn rotates to actuate the valves. In a typical valve actuation system, the camshaft is rotated by a camshaft gear meshing with the engine flywheel and includes multiple non-circular cams that engage valve lifters to open the engine valves and allow the engine valves to close using bias springs. Rocker arms, pushrods, or other intermediate hardware connecting valve lifters to rocker arms can be used to reciprocate and open and close valves.

[0003] In operation, cam followers, such as rollers, directly contact the cam, allowing the valve tappets to reciprocate within bores in the engine housing. Proper operation typically requires the valve tappets to maintain an angular orientation relative to their reciprocating axes, or to allow the valve tappets to rotate within a relatively tightly controlled range. However, internal combustion engine operation is a dynamic process. Valve tappets can become misaligned, potentially requiring repair or even leading to catastrophic engine failure. Numerous designs for limiting valve tappet rotation have been proposed over the years, ranging from the geometry of the valve tappets themselves (relative to each other and / or relative to the engine housing) to specialized spring clips coupled to the valve tappets and configured to engage multiple components of the engine housing. A known anti-rotation roller valve tappet is disclosed in U.S. Patent No. 8,826,874. This '874 patent discloses a roller valve tappet having a first end with a first diameter and a second end with a larger diameter and a plane configured to engage a corresponding planar portion on an adjacent tappet. The strategies proposed in the '874 patent can be applied in various ways, but there is always room for improvement and development of alternative strategies. Summary of the Invention

[0004] In one aspect, an anti-rotation device for a valve tappet in a valve actuation system includes a collar having a sleeve portion and a boss portion. The sleeve portion includes an inner circumferential guide surface that forms a tappet bore defining a bore central axis. The inner circumferential guide surface has a circumferentially varying shape about the bore central axis to limit rotation of a first valve tappet slidably received in the tappet bore. The boss portion includes an outer circumferential surface facing radially outward. The anti-rotation device further includes a bridging connector that extends from the outer circumferential surface for engaging a second valve tappet.

[0005] In another aspect, a valve tappet assembly includes an anti-rotation device with a collar having a sleeve portion including an inner circumferential guide surface forming a tappet bore and a boss portion having an outer circumferential surface. The anti-rotation device further includes a bridging connector extending from the outer circumferential surface. The valve tappet assembly further includes a valve tappet coupled to the anti-rotation device and defining a longitudinal tappet axis extending between a first axial body end and a second axial body end. The valve tappet includes a lifting surface facing the first axial end and a cam follower mounted to the second axial body end.

[0006] In another aspect, an engine valve actuation system includes a rotatable camshaft having a first cam and a second cam, the first cam having a first cam profile about a cam rotation axis, and the second cam having a second cam profile different from the first cam profile about the cam rotation axis. The engine valve actuation system further includes a first valve tappet having a lifting surface configured to actuate a first valve in the engine, and a cam follower contacting the first cam to reciprocate the first valve tappet in response to rotation of the first cam. The engine valve actuation system further includes a second valve tappet having a lifting surface configured to actuate a second valve in the engine, and a cam follower contacting the second cam to reciprocate the second valve tappet in response to rotation of the second cam. The engine valve actuation system further includes an anti-rotation device comprising a collar having a sleeve portion and a bridging connector, the sleeve portion having an inner peripheral guide surface forming a tappet bore and a boss portion having an outer peripheral surface, the bridging connector extending from the outer peripheral surface. The first valve lifter is slidably received in the lifter bore and contacts the inner circumferential guide surface to inhibit rotation of the first valve lifter. The second valve lifter is fixedly coupled to the bridging connector such that the anti-rotation device moves with the second valve lifter and relative to the first valve lifter between a raised position and a lowered position in response to rotation of the second cam. Attached Figure Description

[0007] Figure 1This is a cross-sectional side view of an internal combustion engine according to one embodiment;

[0008] Figure 2 This is a partial cross-sectional schematic view of a valve actuation system according to one embodiment;

[0009] Figure 3 This is an exploded view of a valve assembly according to one embodiment;

[0010] Figure 4 Is it through Figure 1 A cross-sectional view of a portion of the engine;

[0011] Figure 5 This is a schematic view of an anti-rotation device for valve lifters according to one embodiment; and

[0012] Figure 6 yes Figure 5 Another schematic view of the anti-rotation device, which is from Figure 5 Rotate approximately 180°. Detailed Implementation

[0013] See Figure 1 An engine 10 according to one embodiment is shown. Engine 10 may include an internal combustion engine, such as a compression-ignition diesel engine configured to operate using diesel fraction fuel; however, the invention is not limited thereto. Engine 10 includes an engine housing 12 and a crankshaft 14 supported for rotation within the engine housing 12. One or more combustion cylinders 20 are formed in the engine housing 12, and pistons 18 are configured to reciprocate between top dead center and bottom dead center positions in each combustion cylinder 20 in a conventional four-stroke configuration. One of the combustion cylinders 20 is shown and mentioned hereinafter in the singular, and the combustion cylinders may be arranged in any suitable configuration, such as V-type, inline, or another. Connecting rods 16 connect the crankshaft 14 to the pistons 18 in a generally conventional manner. A first engine valve 22 and a second engine valve 24 are configured to open and close fluid communication between the combustion cylinders 20 and gas exchange ducts formed in the engine housing 12. One of engine valves 22 and 24 may include an intake valve and the other may include an exhaust valve; however, in practical implementation strategies, both engine valves 22 and 24 are either intake or exhaust valves, and valve crossarm 34 connects engine valves 22 and 24 to a common rocker arm 36. It should be understood that additional engine valves may be associated with combustion cylinder 20, but... Figure 1 It cannot be seen in the view.

[0014] The rocker arm 36 is part of the engine valve actuation system 26. The valve actuation system 26 may include a rotatable camshaft 28, which is coupled to rotate with the crankshaft 14, for example, via a suitable intermediate gear mechanism. The valve actuation system 26 further includes a plurality of valve tappets, one of which is shown at 42. The valve tappet 42 is connected to the rocker arm 36 via a pushrod 38 and reciprocates within the engine housing 12 to reciprocate the rocker arm 36, thereby opening and closing engine valves 22 and 24 together. The valve tappet 42 includes a lifting surface 66 contacted by the pushrod 38. In other embodiments, the valve tappet may be associated with a single pushrod and a single engine valve, or it may be directly coupled to the rocker arm, or reciprocate according to yet another configuration to actuate the engine valve. Figure 1 The anti-rotation device 80 connected to the valve lifter 42 is shown in the figure, and its details and functions are discussed further here.

[0015] See now Figure 2 and 3 Additional details of the valve actuation system 26, including valve tappet assembly 39, are shown. Valve tappet assembly 39 includes a first valve tappet 40 and a second valve tappet 42. It should be understood that the description and discussion of either valve tappet 40 or 42 herein can be interpreted similarly to the other valve tappet 40 and 42, unless otherwise stated or apparent from the context. Therefore, the terms "first" and "second" as used herein are merely for convenience. The first valve tappet 40 and the second valve tappet 42 (hereinafter referred to as "valve tappet 40" and "valve tappet 42") may be substantially identical and interchangeable for use in engine 10; however, the invention is not limited thereto.

[0016] Valve tappet 40 includes a tappet body 44 defining a longitudinal tappet axis 46. Valve tappet 42 includes a tappet body 48 defining a longitudinal tappet axis 50. Tappet axes 46 and 50 may be oriented perpendicular to a cam rotation axis 29 defined by camshaft 28. In the illustrated embodiment, camshaft 28 includes a first cam 30 or a first cam lobe having a first cam profile about the cam rotation axis 29, and a second cam 32 or a second cam lobe having a second cam profile different from the first cam profile about the cam rotation axis 29. The first and second cam profiles may be substantially identical in shape but have different angular orientations about the cam rotation axis 29. Valve tappet 40 may be configured to actuate one or more intake valves in engine 10, while valve tappet 42 may be configured to actuate one or more exhaust valves in engine 10, and vice versa. Each of valve tappets 40 and 42 may be coupled to an anti-rotation device 80, as discussed further herein.

[0017] In valve lifter 40, such as Figure 3As shown, the longitudinal tappet axis 46 extends between the first axial body end 52 and the second axial body end 54. Both valve tappets 40 and 42 may include a lifting surface, as described above at 66 in valve tappet 42, facing the corresponding first axial tappet body end. Valve tappet 40 includes a cam follower 68 mounted to the second axial body end 54. Valve tappet 42 includes a similarly mounted cam follower 69. Each cam follower 68 and 69 may include rollers that respectively contact the corresponding second cam 32 and first cam 30. The contact between the cam follower 68 and the second cam 32 enables valve tappet 40 to reciprocate in response to rotation of the second cam 32. The contact between the cam follower 69 and the first cam 30 enables valve tappet 42 to reciprocate in response to rotation of the first cam 30.

[0018] As further shown, valve tappet 40 and similar valve tappet 42 include a necked portion 56. The necked portion 56 may include a plurality of arcuate outer surfaces 58 and 60 and a plurality of outer planes 62 and 64 arranged alternately with the arcuate outer surfaces 58 and 60. A cutout 74 may also be formed in the first axial body end 52 to remove mass used to compensate for the mass of the anti-rotation device 80 carried by the valve tappet 40, as discussed further herein. The valve tappet 40 may also include a first bearing hole 70 and a second bearing hole 72 formed in one of the plurality of outer planes (outer plane 64 in the illustrated case) and opened at that outer plane. The bearing holes 70 and 72 are used to connect the valve tappet 40 to the anti-rotation device 80, as discussed further herein. The substantially identical construction of the valve tappet 40 and valve tappet 42 allows for connection to the anti-rotation device 80 in either of the two constructions, as will be discussed later. Figure 3 As is clearly seen in the description, embodiments in which, such as in a repair kit or tool kit, the valve lifter assembly 39 includes, in one of two possible configurations, an assembly in which the valve lifter is coupled to the anti-rotation device 80, and in another of two possible configurations, an embodiment in which the valve lifter is coupled to the anti-rotation device 80. In other cases, the repair kit or tool kit may include two valve lifters, identical or different from each other, assembled together with the anti-rotation device 80, or packaged together but not assembled. As will become further clear from the following description, when positioned for use in the engine 10, the anti-rotation device 80 may be fixedly coupled to a first valve lifter of valve lifters 40 and 42, and slidably coupled to a second valve lifter of valve lifters 40 and 42. When installed in engine 10, the connection between anti-rotation device 80 and valve lifters 40 and 42 will allow reciprocating motion of each of valve lifters 40 and 42, but restrict rotation of each of valve lifters 40 and 42.

[0019] See also Figure 4The diagram shows a top view of valve lifters 40 and 42, which may be present in the engine 10 and positioned for reciprocating motion within the engine housing 12. An anti-rotation device 80 is connected to each valve lifter 40 and 42, and each valve lifter 40 and 42 is capable of reciprocating motion. Figure 4 The illustration shows the movement of the page, but prevents rotation. This function is based on the shape and design of the anti-rotation device 80, which can be fixedly connected to one of the valve lifters 40 and 42, and slidably connected to the other of the valve lifters 40 and 42.

[0020] Still referencing Figure 5 and Figure 6 Additional features of the anti-rotation device 80 are shown. The anti-rotation device 80 includes a collar 82 having a sleeve portion 84 and a boss portion 86. The sleeve portion 84 includes an inner circumferential guide surface 88 forming a tappet bore 90, which defines a bore central axis 92. The inner circumferential guide surface 88 has a circumferentially varying shape about the bore central axis 92 to limit rotation of a first valve tappet slidably received in the tappet bore 90. As described above, the valve tappet 40 or valve tappet 42 may be a first valve tappet slidably received in the tappet bore 90. In practical implementation, the inner circumferential guide surface 88 includes a plurality of inner planes 98 arranged alternately with a plurality of inner arcuate surfaces 100. It should be understood that, for example, the valve tappet 40 may be slidably received in the tappet bore 90 such that outer planes 62 and 64 are positioned facing the inner planes 98, and arcuate outer surfaces 58 and 60 are facing the inner arcuate surfaces 100. As a result, although the valve tappet 40 can slide within the tappet bore 90, it is restricted to rotating about the longitudinal tappet axis 46.

[0021] The boss portion 86 includes an outer peripheral surface 94 facing radially outward relative to the central axis 92 of the hole. The outer peripheral surface 94 may include an outer plane 102 positioned relative to an inner plane 98, such that the radial thickness of the boss portion 86 relative to the central axis 92 of the hole is defined between the outer plane 102 and the inner plane 98. It can also be seen that the sleeve portion 84 includes an arcuate band 104 that begins and terminates at the boss portion 86. The arcuate band 104 may have a semi-circular or other curved outer contour and an inner contour formed by the shapes of the inner surface 98 and the inner arcuate surface 100.

[0022] The anti-rotation device 80 also includes a bridging connector 96 extending from an outer peripheral surface 94 for engaging a second valve lifter, which is either a valve lifter 40 or a valve lifter 42. The anti-rotation device 80 may further include a second bridging connector 97 extending from the outer peripheral surface 94 parallel to the first bridging connector 96. Also in the illustrated embodiment, each of the first bridging connector 96 and the second bridging connector 97 includes a cylindrical protrusion. An embodiment is considered where the first bridging connector 96 and the second bridging connector 97 are separate members mounted in and supported within a boss portion 86. For this purpose, the boss portion 86 may include a first connector hole 106 and a second connector hole 108 formed therein, each opening at an outer peripheral surface 94 within an outer plane 102. The first bridging connector 96 and the second bridging connector 97 are supported in the first connector hole 106 and the second connector hole 108, respectively. Each of the first bridging connector 96 and the second bridging connector 97 may respectively include a pin, such as a cylindrical metal pin, that is interference-fitted into the first connector hole 106 and the second connector hole 108. A suitable adhesive, such as one marketed under a trade name... Those available can enhance the retention force of the first and second bridging connectors 96 and 97 within the first and second connector holes 106 and 108. The ferrule 82 may comprise a single manufactured metal piece. In other embodiments, one or more bridging connectors may be integrally formed with the ferrule. Therefore, the ferrule 82 and one or more bridging connectors 96 and 97 may comprise a single manufactured piece formed from a metallic material and machined into a suitable shape, or may comprise different materials, such as molded and / or machined polymeric materials or glass polymeric materials.

[0023] Return to Figure 4 As can be seen from the top view of the figure, the first bridging connector 96 is visible and received within the carrier hole 70, while the second bridging connector 97 is hidden and located behind the plane of the page. As shown, the first bridging connector 96 and the second bridging connector 97 are offset from each other in the axial direction. Figure 4 The pages inside and outside, and aligned with each other in the circumferential direction around the central axis 92 of the hole. From Figure 4It can also be seen that the outer peripheral surface 94 defines a longitudinal centerline 110 parallel to the central axis 92 of the bore. The first bridging connector 96 and the second bridging connector 97 are offset approximately circumferentially relative to the longitudinal centerline 110. The offset of the bridging connectors 96 and 97 can be understood as meaning that the longitudinal centerline 110 does not intersect the central axis of the bridging connectors 96 and 97, and the centerline 110 does not necessarily intersect the bridging connectors 96 and 97 themselves. The outer plane 64 of the valve tappet 40 can also define the longitudinal centerline 114, and the bridging connectors 96 and 97, as well as the bearing bores 70 and 72, are similarly offset circumferentially about the tappet axis 46 relative to the longitudinal centerline 114. Figure 4 As shown, when installed in engine 10 for use, engine housing protrusion 13 is positioned adjacent to each of valve lifters 40 and 42. The offset of the first bridging connector 96 and the second bridging connector 97 relative to the longitudinal centerlines 110 and 114 helps to package the valve lifter assembly 39 for use in engine 10 without interfering with engine housing protrusion 13 or other structures. Also in the illustrated embodiment, anti-rotation device 80 includes a first axial end face 111 and a second axial end face 112. The second axial end face 112 may be substantially planar, while the first axial end face 111 may include two separate substantially planar surfaces, including a first planar portion located on the arcuate band 104 and a second planar portion located partially on the arcuate band 104 and partially on the boss portion 86. As shown, the axial thickness of the anti-rotation device 80 between the first axial end face 111 and the second axial end face 112 can be less through the arcuate band 104 than through the boss portion 86.

[0024] Industrial applicability

[0025] Referring generally to the accompanying drawings, during the operation of engine 10, a fuel-air mixture is burned in combustion cylinder 20 to push piston 18 toward bottom dead center, thereby rotating crankshaft 14 via connecting rod 16. Camshaft 28 typically rotates at half engine speed in a conventional four-stroke mode, causing valve lifters 40 and 42 to reciprocate to open and close the corresponding engine valves. Each of valve lifters 40 and 42 includes a lifting surface that contacts a pushrod and is configured to actuate the corresponding engine valve as described, wherein corresponding cam followers 68 and 69 contact a second cam 32 and a first cam 30 on camshaft 28 to cause valve lifters 40 and 42 to reciprocate at appropriate timing.

[0026] As discussed herein, the anti-rotation device 80 can be fixedly coupled to bridging connectors 96 and 97. The valve lifter 42 is slidably received in the lifter bore 90. Contact between the inner circumferential guide surface 88 and the valve lifter 42 inhibits rotation of the valve lifter 42. In response to rotation of the camshaft 28, particularly the cam 32 in the illustrated embodiment, the fixed coupling of the valve lifter 40 to bridging connectors 96 and 97 causes the anti-rotation device 80 to move together with the valve lifter 40 relative to the valve lifter 42 between a raised position and a lowered position. Figure 2 The diagram roughly illustrates valve lifters 40 and 42, which may be in a lowered or lowered position, causing the corresponding engine valves to close. As the camshaft 28 rotates about the cam axis 29, valve lifters 40 will be pushed up and down in response to the rotation of the cam 32, causing the anti-rotation device 80 to move up and down relative to valve lifters 42 depending on the current raised or lowered state of the valve lifters 42. Different cam profiles and / or cam angle orientations can give different results regarding whether the relative movement is upward or downward at any given time; however, in all cases, the anti-rotation device 80 and valve lifters 42 reciprocate freely relative to each other, but valve lifters 42 are prevented from rotating or are restricted to rotating within a relatively narrow range about the lifter axis 50.

[0027] This specification is for illustrative purposes only and should not be construed as limiting the scope of the invention in any way. Therefore, those skilled in the art will understand that various modifications can be made to the currently disclosed embodiments without departing from the full and reasonable scope and spirit of the invention. Other aspects, features, and advantages will become apparent from a study of the accompanying drawings and appended claims. As used herein, the article “a / an” is intended to include one or more items and is interchangeable with “one or more.” The term “a” or similar language is used where only one item is desired. Furthermore, as used herein, the terms “has / have / having” and the like are intended to be open-ended terms. Additionally, the phrase “based on” is intended to mean “at least partially based on” unless otherwise explicitly stated.

Claims

1. An anti-rotation device for a valve lifter in a valve actuation system, comprising: A collar, comprising a sleeve portion and a boss portion; The sleeve portion includes an inner circumferential guide surface that forms a push rod hole that defines the central axis of the hole; The inner circumferential guide surface has a shape that varies circumferentially around the central axis of the hole to limit the rotation of the first valve tappet that is slidably received in the tappet hole; The boss portion includes an outer peripheral surface facing the radially outward direction; and A first bridging connector and a second bridging connector extend from the outer peripheral surface for engaging with a second valve lifter. Each of the first bridging connector and the second bridging connector is axially offset from each other and circumferentially aligned with each other.

2. The apparatus of claim 1, wherein: The inner peripheral guiding surface includes a plurality of inner planes arranged alternately with a plurality of inner arcuate surfaces; The outer peripheral surface includes an outer plane positioned relative to one of a plurality of inner planes, and the radial thickness of the boss portion is defined between the outer plane and one of the plurality of inner planes; The sleeve portion includes an arcuate band that begins at and ends at the boss portion.

3. The apparatus as claimed in claim 1 or 2, wherein: A first connector hole and a second connector hole, each opening at the outer peripheral surface, are formed in the boss portion, and the first bridging connector and the second bridging connector are respectively supported in the first connector hole and the second connector hole; and Each of the first bridging connector and the second bridging connector includes a pin.

4. A valve tappet assembly, comprising: Anti-rotation device, comprising: The collar and a first bridging connector and a second bridging connector, the collar having a sleeve portion and a boss portion, the sleeve portion having an inner peripheral guide surface forming a tappet hole, the boss portion having an outer peripheral surface, the first bridging connector and the second bridging connector extending from the outer peripheral surface, each of the first bridging connector and the second bridging connector being axially offset from each other and circumferentially aligned with each other. and A valve tappet, which is connected to the anti-rotation device and defines a longitudinal tappet axis extending between a first axial body end and a second axial body end, and the valve tappet includes a lifting surface facing the first axial body end and a cam follower mounted on the second axial body end.

5. The valve lifter assembly as claimed in claim 4, wherein: Each of the first bridging connector and the second bridging connector includes a cylindrical protrusion; and The valve lifter includes a first bearing hole and a second bearing hole, the first bearing hole and the second bearing hole respectively receiving the first bridging connector and the second bridging connector to connect the valve lifter to the anti-rotation device.

6. The valve lifter assembly as claimed in claim 5, wherein: The tappet hole defines the central axis of the hole; and The valve tappet assembly further includes a second valve tappet that is slidably received within the tappet bore.

7. The valve tappet assembly of claim 4 or 5, wherein the valve tappet is fixedly coupled to the first bridging connector and the second bridging connector and has a fixed axial position relative to the collar, and the valve tappet assembly further includes a second valve tappet slidably received within the tappet bore and having a movable axial position relative to the collar.

8. An engine valve actuation system, comprising: A rotatable camshaft includes a first cam having a first cam profile about a first cam axis of rotation, and a second cam having a second cam profile about the cam axis of rotation that is different from the first cam profile. A first valve tappet includes a lifting surface and a cam follower, the lifting surface being configured to actuate a first valve in the engine, and the cam follower contacting a first cam to reciprocate the first valve tappet in response to rotation of the first cam. The second valve tappet includes a lifting surface and a cam follower, the lifting surface being configured to actuate a second valve in the engine, and the cam follower contacting a second cam to reciprocate the second valve tappet in response to rotation of the second cam. An anti-rotation device includes: a collar and a first bridging connector and a second bridging connector, the collar having a sleeve portion and a boss portion, the sleeve portion having an inner circumferential guide surface forming a tappet hole, the boss portion having an outer circumferential surface, the first bridging connector and the second bridging connector extending from the outer circumferential surface, each of the first bridging connector and the second bridging connector being axially offset from each other and circumferentially aligned with each other. The first valve tappet is slidably received in the tappet bore and contacts the inner circumferential guide surface to suppress rotation of the first valve tappet; and The second valve lifter is fixedly connected to the first bridging connector and the second bridging connector, such that the anti-rotation device moves together with the second valve lifter and relative to the first valve lifter between a raised position and a lowered position in response to the rotation of the second cam.

9. The system of claim 8, wherein: Each of the first bridging connector and the second bridging connector includes a cylindrical protrusion; The second valve tappet includes a first bearing hole and a second bearing hole formed therein, and receives the first bridging connector and the second bridging connector respectively; The inner peripheral guiding surface includes a plurality of inner planes arranged alternately with a plurality of inner arcuate surfaces; The outer peripheral surface includes an outer plane positioned relative to one of a plurality of inner planes, such that the radial thickness of the boss portion is limited between the outer plane and one of the plurality of inner planes; and The sleeve portion includes an arcuate band that begins and ends at the boss portion.

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