Valve lifter anti-rotation device with cantilever bridge

Abstract

An engine valve actuation system includes a camshaft rotatable in an engine and a composite collar including a mounting sleeve, a guide sleeve, and a bridge connecting the guide sleeve to the mounting sleeve in cantilever fashion. A first valve lifter is interference fit in the mounting sleeve, and a second valve lifter is slide fit in the guide sleeve. First and second lifter bores accommodating the first and second valve lifters are congruent, and the first and second valve lifters can be substantially identical. The composite collar reciprocates with the interference fit first valve lifter, slideably accommodates the slide fit second valve lifter, and restricts rotation of both in service.

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 lifter. Background Technology

[0002] Internal combustion engines typically employ multiple valves to control fluid connections between different parts of the engine, such as controlling the fluid connection between 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 (the linkage is rotatable to actuate the valves). In a typical valve actuation system, the camshaft is driven to rotate by a cam gear meshing with the engine flywheel and includes multiple non-circular cams that engage with valve lifters to open engine valves and allow engine valves to close via bias springs. A rockerarm is provided to reciprocate to open and close the valves, while a pushrod or other intermediate hardware connects the valve lifter to the rockerarm.

[0003] During operation, the cam follower (such as a roller) directly contacts the cam, enabling the valve lifter to reciprocate within a bore in the engine housing. Normal operation typically requires the valve lifter to maintain an angular orientation relative to its axis of reciprocation, or to be allowed to rotate within a relatively tight control range. However, the operation of an internal combustion engine is a dynamic process. The valve lifter can become misaligned, potentially requiring maintenance, or even leading to catastrophic engine failure. Over the years, numerous designs for limiting valve lifter rotation have been proposed, ranging from the geometry of the valve lifters themselves relative to each other and / or relative to the engine housing, to specialized spring clips coupled to the valve lifter and configured to engage with parts of the engine housing. A known anti-rotation roller valve lifter is disclosed in U.S. Patent No. 8,826,874. The '874 patent proposes a roller lifter with a first end having a first diameter, a second end having a larger diameter, and its flat surface configured to engage a corresponding flat surface on an adjacent lifter. The strategy proposed in the '874 patent may have various applications, but there is always room for improvement and development of alternative strategies. Summary of the Invention

[0004] In one aspect, a composite collar for limiting the rotation of a valve lifter in an engine during in-service includes an integral collar body having a mounting sleeve, a guide sleeve, and a bridging member attaching the guide sleeve to the mounting sleeve, and an outer peripheral surface partially formed on each of the mounting sleeve, the guide sleeve, and the bridging member. The mounting sleeve includes a first inner peripheral surface forming a first lifter bore for receiving a first valve lifter, and the first lifter bore defines a first collar axis, a first major diameter, and a first minor diameter. The guide sleeve includes a second inner peripheral surface forming a second lifter bore for receiving a second valve lifter, and the second lifter bore defines a second collar axis, a second major diameter, and a second minor diameter. The first and second lifter bores are aligned. Compared to the dimensions of the first major diameter and the first minor diameter, the second lifter bore is enlarged relative to the first lifter bore based on the dimension of at least one of the second major diameter or the second minor diameter.

[0005] On the other hand, a valve lifter assembly includes a composite collar for limiting rotation of the valve lifter during maintenance. The composite collar includes a mounting sleeve having a first inner peripheral surface forming a first lifter bore, a guide sleeve having a second inner peripheral surface forming a second lifter bore, a bridging member attaching the guide sleeve to the mounting sleeve, and an outer peripheral surface partially formed on each of the mounting sleeve, the guide sleeve, and the bridging member. The valve lifter assembly also includes a valve lifter having a first lifter end and a second lifter end, a lifting surface facing the first lifter end, a cam follower mounted to the second lifter end, and the first lifter end being positionable within either the first or second lifter bore. The second lifter bore is enlarged relative to and coincides with the first lifter bore, such that the valve lifter has an interference fit with the mounting sleeve and a sliding fit with the guide sleeve.

[0006] In another aspect, an engine valve actuation system includes a camshaft having a first cam and a second cam, and rotatable about a rotational axis of the cams. The system also includes a compound collar having: a mounting sleeve having a first inner circumferential surface forming a first lifter bore; a guide sleeve having a second inner circumferential surface forming a second lifter bore; and a bridging member attaching the guide sleeve to the mounting sleeve. The system further includes: a first valve lifter, interference-fitted within a first lifter bore, and including: 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 lifter in response to rotation of the first cam. The system also includes: a second valve lifter, slidably fitted within a second lifter bore, and including: 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 lifter in response to rotation of the second cam. The first and second lifter bores are congruent, and the first and second valve lifters are substantially identical. Attached Figure Description

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

[0008] Figure 2 yes Figure 1 A partial cross-sectional perspective view of a portion of the engine;

[0009] Figure 3 This is a schematic diagram of a valve lifter assembly according to one embodiment;

[0010] Figure 4 This is a side sectional view of a valve lifter assembly according to one embodiment;

[0011] Figure 5 This is a top view of a valve lifter assembly according to one embodiment;

[0012] Figure 6 This is a top view of a valve lifter according to one embodiment;

[0013] Figure 7 This is a side sectional view of a composite collar according to one embodiment;

[0014] Figure 8 This is a perspective view of a composite collar according to one embodiment; and

[0015] Figure 9 This is a top view of a composite collar according to one embodiment. Detailed Implementation

[0016] Reference Figure 1An engine 10 according to one embodiment is shown. Engine 10 includes an internal combustion engine, such as a compression-ignition diesel engine configured to operate on diesel fraction fuels; 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 in each combustion cylinder 20 between a top-dead-center position and a bottom-dead-center position in a conventional four-stroke mode. The combustion cylinders 20 can be arranged in any suitable configuration (such as V-shaped, straight, or other configurations), with one combustion cylinder 20 shown and indicated hereinafter in the singular. 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 actual implementation, both engine valves 22 and 24 are either intake or exhaust valves, and valve bridge 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 is not visible in the view.

[0017] The rocker arm 36 is part of the engine valve actuation system 26. The valve actuation system 26 may include a rotatable camshaft 28 coupled to, for example, rotate with the crankshaft 14 via a suitable intermediate gear mechanism. The valve actuation system 26 also includes a plurality of valve lifters, one of which is shown as 40. The valve lifter 40 is coupled to the rocker arm 36 via a push rod 38 and reciprocates within the engine housing 12 to reciprocate the rocker arm 36 to open and close engine valves 22 and 24 together. The valve lifter 42 includes a lifting surface 66 that contacts the push rod 38. In other embodiments, the valve lifter may be associated with a single engine valve, or may be directly coupled to the rocker arm, or reciprocate to actuate engine valves according to yet another architecture. Figure 1 The diagram shows the valve lifter 40 and its function in limiting valve lifters. Figure 1 Another valve lifter, invisible in the middle, rotates during maintenance on a composite collar 80. Figure 1 It is connected to valve lifter 40, the details and functions of which will be discussed further in this article.

[0018] Now refer to Figure 2 and Figure 3Additional details of the valve actuation system 26, including a valve lifter assembly 39, are shown. The valve lifter assembly 39 includes a valve lifter 40 (“first” valve lifter) and a second valve lifter 42. It should be understood that, unless otherwise indicated or clearly apparent from the context, the description and discussion of either valve lifter 40 or 42 can be understood as analogous to the other. Therefore, the terms “first” and “second” are used herein only for convenience. Valve lifter 40 and valve lifter 42 may be substantially identical except for manufacturing differences and may be used interchangeably in the engine 10. However, the invention is not strictly limited, and in some cases, this teaching can be applied to valve lifters with different configurations.

[0019] Valve lifter 40 includes an elongated lifter body 44 defining a longitudinal lifter axis 46. Valve lifter 42 includes an elongated lifter body 48 defining a longitudinal lifter axis 50. Lifter axes 46 and 50 may be oriented perpendicular to the axis of rotation 29 of the cam about which the camshaft 28 rotates. In the illustrated embodiment, the camshaft 28 includes a first cam or first cam lob 30 having a first cam profile about the axis of rotation 29 of the cam, and a second cam or second cam lob 32 having a second cam profile different from the first cam profile about the axis of rotation 29 of the cam. The first cam profile and the second cam profile may be substantially the same in shape, but have different angular orientations about the axis of rotation 29 of the cam. Valve lifter 40 may be configured to actuate one or more intake valves in engine 10, while valve lifter 42 may be configured to actuate one or more exhaust valves in engine 10, and vice versa. Each of valve lifters 40 and 42 may be coupled to a compound collar 80, which will be discussed further herein. Figure 3 As shown, in valve lifter 40, lifter axis 46 extends between a first lifter end or first axial body end 52 and a second lifter end or second axial body end 54. Valve lifter 40 and valve lifter 42 may each include a lifting surface, as shown above at 66 in valve lifter 40, with the lifting surface facing the corresponding first lifter end 52. Valve lifter 40 includes a cam follower 68 mounted to the second lifter end 54. Valve lifter 42 includes a similarly mounted cam follower 69. Each of cam followers 68 and 69 may include rollers that respectively contact corresponding cams 30 and 32. The contact between cam follower 68 and the first cam 30 enables valve lifter 40 to reciprocate in response to rotation of the first cam 30. The contact between cam follower 69 and the second cam 32 enables valve lifter 42 to reciprocate in response to rotation of the second cam 32.

[0020] As further shown, valve lifter 40 and similar valve lifter 42 include a necked portion 56. The necked portion 56 may include a plurality of arcuate outer surfaces 58 and 60 arranged in an alternating manner, and a plurality of flat outer surfaces 62 and 64. The substantially identical configuration of valve lifters 40 and 42, and their configuration relative to the composite collar 80, allows either valve lifter 40 or 42 to be engaged with the composite collar 80 in either of two configurations: an interference fit mounting configuration with a portion of the composite collar 80 and a sliding fit mounting configuration with another portion of the composite collar 80, which will be discussed further herein. Valve lifter assembly 39 may be combined with the composite collar 80 as an assembly of one or more of valve lifters 40 and 42, provided in one or both of the two mounting configurations (e.g., as a service package, kit, or other aftermarket component). As will become further apparent from the following description, when positioned and installed on engine 10 for service, the composite collar 80 is fixedly connected to the first of valve lifters 40 and 42 by an interference fit and to the second of valve lifters 40 and 42 by a sliding fit. When installed in engine 10, the connection of the composite collar 80 to valve lifters 40 and 42 will allow reciprocating motion of each of valve lifters 40 and 42, but will restrict rotation of each of valve lifters 40 and 42 or limit rotation to a relatively narrow range.

[0021] Still referencing Figure 5 The diagram shows a top view of the valve lifter assembly 39, illustrating that valve lifters 40 and 42 may appear to be coupled to and positioned within the composite collar 80. The composite collar 80 includes a one-piece collar body 82 having a mounting sleeve 84, a guide sleeve 86, a bridging member 88 cantileveredly attaching the guide sleeve 86 to the mounting sleeve 84, and an outer peripheral surface 90 partially formed on each of the mounting sleeve 84, the guide sleeve 86, and the bridging member 88. The outer peripheral surface 90 may be curved on each of the mounting sleeve 84 and the guide sleeve 86. See also... Figure 6 The diagram shows a valve lifter 40, including a top view showing the outlines of surfaces 62, 64, 60, and 58. It should be noted that the valve lifter 40, including the necked portion 56, has a shape complementary to the internal shapes of the mounting sleeve 84 and the guide sleeve 86. However, it should be remembered that the valve lifter 40 can have an interference fit configuration with a portion of the composite collar 80, namely the mounting sleeve 84, and a sliding fit configuration with another portion of the composite collar 80, namely the guide sleeve 86. The valve lifter 42 can be similarly coupled to the composite collar 80 in either configuration. Therefore, as... Figure 5As shown, when assembled into engine 10 for maintenance, the reciprocating motion of valve lifter 40 will cause composite collar 80 to reciprocate relative to valve lifter 42 in and out of the page. Correspondingly, valve lifter 42 can also reciprocate relative to composite collar 80 and valve lifter 40. Figure 5 The page moves back and forth in the view.

[0022] Still referencing Figure 4 , Figure 7 , Figure 8 as well as Figure 9 The integrated collar body 82 may include a flat and continuous upper end face 112 on the mounting sleeve 84, guide sleeve 86, and bridging member 88. The guide sleeve 86 may include a first lower end face 114, which is flat and arranged opposite to the upper end face 112. The mounting sleeve 84 may include a downwardly overhanging sleeve wall 116 having a second lower end face 118, which is arranged opposite to the upper end face 112 and is axially located outside the first lower end face 114. The second lower end face 118 is flat and extends circumferentially around the first lifter bore 94, which will be discussed below, on the sleeve wall 116, forming an annular stop surface to contact the annular stop member 117 on the valve lifter 40. Therefore, during the interference fit between the composite collar 80 and the valve lifter 40, the integral collar body 82 can be pressed against the necked portion 56 until the second lower end face 118 contacts the annular stop 117.

[0023] Mounting sleeve 84 includes a first inner circumferential surface 92 forming a first lifter bore 94 for receiving valve lifter 40. Guide sleeve 86 includes a second inner circumferential surface 102 forming a second lifter bore 104 for receiving valve lifter 42. The first lifter bore 94 and the second lifter bore 104 are congruent. In a practical embodiment, the first lifter bore 94 and the second lifter bore 104 may have substantially the same shape and substantially the same angular orientation about their respective axes in the composite collar 80, but may differ slightly in size. This arrangement allows either valve lifter 40 or 42 to have an interference fit mounting configuration with mounting sleeve 84 and either valve lifter 40 or 42 to have a sliding fit mounting configuration with guide sleeve 86. In the context of this invention, shapes that are different but have generally coincident major and minor axes when overlapping can also be considered congruent. Shapes that are different and whose major and minor axes do not coincide when overlapping are unlikely to be considered congruent.

[0024] The first lifter bore 94 defines a first set of ring axis 96, a first large diameter 98, and a first small diameter 100. The second lifter bore 104 defines a second set of ring axis 106, a second large diameter 108, and a second small diameter 110. Compared to the dimensions of the first large diameter 98 and the first small diameter 100, the second lifter bore 104 is enlarged relative to the first lifter bore 94 based on the dimensions of at least one of the second large diameter 108 or the second small diameter 110, i.e., the sliding fit valve lifter 42 in the second lifter bore 104 corresponds to the interference fit valve lifter 40 in the first lifter bore 94.

[0025] It should also be noted that, such as Figure 4 and Figure 7 As best depicted, the first inner circumferential surface 92 defines a complete axial length 135 extending from the upper end face 112 to the second lower end face 118, parallel to the axis 96 of the first ring. A first large diameter 98 may have a larger dimension along a small portion of the complete axial length 135 and a smaller dimension along a small portion of the complete axial length 135, thereby defining an interference fit length 136. The first large diameter 98 may have a larger dimension along a large portion of the complete axial length 135, thereby defining a clearance fit length 138. The interference fit length 136 between the first lifting end 52 and the mounting sleeve 84 may be equal to a small portion of the complete axial length 135. The clearance fit length 138 between the first lifting end 52 and the mounting sleeve 84 may be equal to a large portion of the complete axial length 135. The first inner circumferential surface 92 may have a cylindrical shape along the clearance fit length 138.

[0026] Therefore, from Figure 4 and Figure 7 It can be seen that only a small portion of the first inner circumferential surface 92 presses against the valve lifter 40, and a gap 140 is formed between the downwardly hanging sleeve wall 116 and the valve lifter 40. The downwardly hanging sleeve wall 116 may abut against or touch the annular stop 117 on the valve lifter 40. In another practical embodiment, the second lifter bore 104 is enlarged relative to the first lifter bore 94 based on the dimensions of both the second large diameter 108 and the second small diameter 110, compared to the dimensions of the first large diameter 98 and the first small diameter 100. In some embodiments, the second large diameter 108 is at least 3% larger than the first large diameter 98, and the second small diameter 110 is at least 6% larger than the first small diameter 100. Figure 9Most clearly depicted, the integral collar body 82 may have a footprint in the axial projection plane, including a first arc 142 formed by the outer peripheral surface 90 on the mounting sleeve 84 and starting and terminating at the bridging member 88. The footprint of the integral collar body 82 may also include a mirrored arc 144 formed by the outer peripheral surface 90 on the guide sleeve 86 and also starting and terminating at the bridging member 88.

[0027] In the illustrated embodiment, each of the first inner circumferential surface 92 and the second inner circumferential surface 102 includes arcuate inner walls 120, 122 and 124, 126, respectively, defining a first large diameter 98 and a second large diameter 108. The arcuate inner walls 120, 122 and 124, 126 are alternately arranged with the flat inner walls 128, 130 and 132, 134 of the first inner circumferential surface 92 and the second inner circumferential surface 102, respectively, defining a first small diameter 100 and a second small diameter 110. In other embodiments, different inner circumferential surface configurations may be employed, such as elliptical configurations, various polygonal configurations, or any other non-circular shape suitable for an interference fit with a valve lifter with respect to the first inner circumferential surface 92 and for a sliding fit with a valve lifter with respect to the second inner circumferential surface 102 while limiting its rotation.

[0028] Industrial applicability

[0029] Referring generally to the accompanying drawings, during engine 10 operation, a fuel-air mixture is burned in combustion cylinder 20 to push piston 18 to bottom dead center, thereby rotating crankshaft 14 via connecting rod 16. Camshaft 28 rotates at half engine speed in a conventional four-stroke mode to cause valve lifters 40 and 42 to reciprocate, opening and closing associated engine valves. Each of valve lifters 40 and 42 includes a lifting surface that contacts a pushrod configured to actuate the corresponding engine valve, as described herein. Cam followers 68 and 69 contact cams 30 and 32 on camshaft 28 to cause valve lifters 40 and 42 to reciprocate at appropriate times. Compound collar 80 is fixedly coupled to valve lifter 40 and slidably accommodates valve lifter 42. Contact between second inner circumferential surface 102 and valve lifter 42 inhibits rotation of valve lifter 42. The fixed connection between the valve lifter 40 and the guide sleeve 86 causes the composite collar 80 to move between the raised and lowered positions relative to the valve lifter 42 in response to the rotation of the camshaft 28, particularly the rotation of the first cam 30.

[0030] exist Figure 2In the diagram, valve lifter 40 is shown as potentially located in the lowered position, causing the relevant engine valve to close. Valve lifter 42 is shown as potentially located near the raised position, causing the relevant engine valve to open. When camshaft 28... Figure 2 When the valve lifter 42 is in a rotating state, it will reciprocate relative to the compound collar 80, but is restricted from rotating about the lifter axis 50. The valve lifter 40 and compound collar 80 will reciprocate together with the valve lifter 40, and are also restricted from rotating about the lifter axis 46. Alternative cam arrangements and cam profiles can produce different modes of reciprocating motion of the valve lifters 40 and 42 relative to each other, but at any given time, the valve lifters 40 and 42 will be free to reciprocate, depending on the cam angle, and will be prohibited from rotating or restricted to rotating about their respective lifter axes 46 and 50 within a relatively tightly controlled, narrow range (e.g., within ±5°).

[0031] This description 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 proper scope and spirit of the invention. Other aspects, features, and advantages will become apparent upon examination of the accompanying drawings and appended claims. As used herein, the articles “a” and “an” should include one or more items and may be used interchangeably with “one or more.” In cases involving only one item, the word “an” or similar terminology is used. Furthermore, as used herein, the words “has,” “have,” “having,” etc., should be open-ended terms. Additionally, unless explicitly stated otherwise, the phrase “based on” should mean “at least partially based on.”

Claims

1. A composite collar for limiting the rotation of a valve lifter in an engine during maintenance, comprising: An integral collar body includes a mounting sleeve, a guide sleeve, a bridging member for attaching the guide sleeve to the mounting sleeve, and an outer peripheral surface partially formed on each of the mounting sleeve, the guide sleeve, and the bridging member. The mounting sleeve includes a first inner circumferential surface, the first inner circumferential surface forming a first lifter hole for receiving a first valve lifter, the first lifter hole defining a first sleeve axis, a first large diameter, and a first small diameter; The guide sleeve includes a second inner circumferential surface, the second inner circumferential surface forming a second lifter hole for receiving a second valve lifter, the second lifter hole defining a second collar axis, a second large diameter, and a second small diameter; The drilling holes for the first and second lifting devices are identical; and Compared to the dimensions of the first large diameter and the first small diameter, the second lifting device borehole is enlarged relative to the first lifting device borehole based on the dimension of at least one of the second large diameter or the second small diameter.

2. The composite collar according to claim 1, wherein: The outer peripheral surface is curved on each of the mounting sleeve and the guide sleeve; Each of the first inner circumferential surface and the second inner circumferential surface includes an arcuate inner wall, thereby defining a first large diameter and a second large diameter, the arcuate inner wall being alternately arranged with a flat inner wall, thereby defining a first small diameter and a second small diameter; The integrated collar body includes an upper end face partially formed on the mounting sleeve, the guide sleeve, and the bridging member; The guide sleeve includes a first lower end face, which is arranged opposite to the upper end face; and The mounting sleeve includes a downwardly hanging sleeve wall having a second lower end face, which is arranged opposite to the upper end face.

3. The composite collar according to claim 2, wherein: The first inner circumferential surface has a complete axial length extending from the upper end face to the second lower end face; The first large diameter has a small size along a small portion of the full axial length, thereby defining the interference fit length, and has a large size along the majority of the full axial length, thereby defining the clearance fit length; The integrated collar body has a coverage area on the axial projection plane, including a first arc formed by the outer peripheral surface of the mounting sleeve and a mirror arc formed by the outer peripheral surface of the guide sleeve; Each of the first arc and the mirrored arc begins and terminates at the bridging member; The second lower end face is located axially outside the first lower end face; and The second lower end face is flat and extends circumferentially around the hole in the first lifter on the sleeve wall, forming an annular stop surface to contact the annular stop on the first valve lifter.

4. The composite collar according to claim 2 or 3, wherein: Compared to the dimensions of the first large diameter and the first small diameter, the second lifting device borehole is enlarged relative to the first lifting device borehole based on the dimensions of both the second large diameter and the second small diameter; and The second largest diameter is at least 3% larger than the first largest diameter, and the second smallest diameter is at least 6% larger than the first smallest diameter.

5. A valve lifter assembly, comprising: A composite collar for limiting the rotation of a valve lifter during maintenance includes a mounting sleeve having a first inner peripheral surface forming a first lifter bore, a guide sleeve having a second inner peripheral surface forming a second lifter bore, a bridging member attaching the guide sleeve to the mounting sleeve, and an outer peripheral surface partially formed on each of the mounting sleeve, the guide sleeve, and the bridging member. A valve lifter includes a first lifter end and a second lifter end, a lifting surface facing the first lifter end, and a cam follower mounted to the second lifter end. The first lifter end can be positioned within either the first lifter bore or the second lifter bore. The second lifting device bore is enlarged relative to and coincides with the first lifting device bore, so that the valve lifting device has an interference fit with the mounting sleeve and a sliding fit with the guide sleeve.

6. The valve lifter assembly according to claim 5, wherein: The first lifting device drills a hole to define the first set of ring axes; The first inner circumferential surface defines the complete axial length; The first lifting device end is interference-fitted with the mounting sleeve inside the first lifting device borehole; The interference fit length between the first lifting device end and the mounting sleeve is equal to a small portion of the complete axial length; The clearance fit length between the first lifting device end and the mounting sleeve is equal to most of the complete axial length; The composite collar has a coverage area on the axial projection plane, including a first arc formed by the outer peripheral surface of the mounting sleeve and a mirror arc formed by the outer peripheral surface of the guide sleeve. Each of the first arc and the mirrored arc begins and terminates at the bridging member; and The mounting sleeve includes a downwardly suspended sleeve wall that contacts an annular stop on the valve lifter, and a gap extends radially between the downwardly suspended sleeve wall and the valve lifter.

7. The valve lifter assembly according to claim 5 or 6, wherein: Each of the first inner circumferential surface and the second inner circumferential surface includes an arcuate inner wall that is alternately arranged with a flat inner wall; The first lifting device bore defines a first set of ring axes, a first large diameter between their respective arcuate inner walls, and a first small diameter between their respective flat inner walls; The second lifting device bore defines the second set of ring axes, the second largest diameter between their respective arcuate inner walls, and the second smallest diameter between their respective flat inner walls; and Compared to the dimensions of the first large diameter and the first small diameter, the second lifting device borehole is enlarged relative to the first lifting device borehole based on the dimension of at least one of the second large diameter and the second small diameter.

8. An engine valve actuation system, comprising: A camshaft, including a first cam and a second cam, is rotatable about the rotation axis of the cams; A composite collar includes a mounting sleeve having a first inner peripheral surface forming a first lifting device borehole, a guide sleeve having a second inner peripheral surface forming a second lifting device borehole, and a bridging member for attaching the guide sleeve to the mounting sleeve. A first valve lifter, interference-fitted within a first lifter bore, and includes a lifting surface configured to actuate a first valve in an engine and a cam follower that contacts the first cam to reciprocate the first valve lifter in response to rotation of the first cam. The second valve lifter is slidably fitted within the second lifter bore and includes a lifting surface configured to actuate the second valve in the engine and a cam follower that contacts the second cam to reciprocate the second valve lifter in response to rotation of the second cam. The drilling holes for the first and second lifting devices are identical; and The first valve lifter and the second valve lifter are essentially the same. in: The first lifting device drill hole defines the first set of ring axis, the first large diameter, and the first small diameter; The second lifting device borehole defines the second ring axis, the second large diameter, and the second small diameter; and Compared to the dimensions of the first large diameter and the first small diameter, the second lifting device borehole is enlarged relative to the first lifting device borehole based on the dimension of at least one of the second large diameter and the second small diameter.

9. The system according to claim 8, wherein: The composite collar includes a flat and continuous upper end face on the mounting sleeve, the guide sleeve, and the bridging member; The guide sleeve includes a first lower end face, which is flat and arranged opposite to the upper end face; and The mounting sleeve includes a downwardly overhanging sleeve wall having a second lower end face, the second lower end face being flat and arranged opposite to the upper end face and located axially outside the first lower end face.

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